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Jansen MW, Münker C, Pakulla JJ, Hasenstab-Dübeler E, Marien CS, Schulz T, Kirchenbaur M, Schneider KP, Tordy R, Schmitt V, Wombacher F. Petrogenesis of volcanic rocks from the Quaternary Eifel volcanic fields, Germany: detailed insights from combined trace-element and Sr-Nd-Hf-Pb-Os isotope data. CONTRIBUTIONS TO MINERALOGY AND PETROLOGY. BEITRAGE ZUR MINERALOGIE UND PETROLOGIE 2024; 179:57. [PMID: 38736869 PMCID: PMC11081932 DOI: 10.1007/s00410-024-02137-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Accepted: 04/19/2024] [Indexed: 05/14/2024]
Abstract
Quaternary rocks from the East and West Eifel volcanic fields in western Germany are a key suite of intraplate volcanic rocks that can provide insights into volcanism of the Central European Volcanic Province (CEVP) and into continental intraplate volcanism in general. We present a comprehensive dataset for Eifel lavas including isotope as well as major and trace element data for 59 samples covering representative compositions of the different volcanic fields. In line with previous studies, the lavas are all SiO2-undersaturated, alkaline-rich and mainly comprise primitive basanites, melilitites, and nephelinites (Mg# ≥ 57). Geochemical compositions of samples from both volcanic subfields display distinct differences in their trace-element as well as radiogenic isotope compositions, largely confirming previous subdivisions. Coupled trace-element and radiogenic Sr-Nd-Hf-Pb-Os isotope compositions can now provide firm evidence for spatially heterogeneous mantle sources and compositionally distinct magmatic pulses. Within the West Eifel Field, Sr-Nd-Pb isotope compositions of the younger (≤80 ka), ONB-suite (olivine-nephelinite-basanite) are similar to FOZO (FOcal ZOne) or the EAR (European Asthenospheric Reservoir) and resemble compositions that have been previously reported from plume-sourced ocean island basalts (OIB). In marked difference, older (700 Ma to 80 ka) volcanic rocks from the F-suite (Foidite) in the West Eifel field and from the entire east Eifel Field tap a more enriched mantle component, as illustrated by more radiogenic Sr isotope (86Sr/87Sr up to 0.705408) and variable Pb isotope compositions (206Pb/204Pb = 18.61-19.70, 207Pb/204Pb = 15.62-15.67 and 208Pb/204Pb = 38.89-39.76). Combined trace-element compositions of ONB-suite samples are in good agreement with results from batch melting models suggesting a hybrid composition of Eifel magmas formed through mixing 10% of a FOZO-like melt with 90% of a DMM-like melt, similar to melts from the Tertiary HEVF. However, radiogenic Sr-Nd-Pb isotope compositions of F-suite and EEVF and some ONB lavas require the admixture of melts from lithospheric mantle sources. Elevated Nb/Ta and Lu/Hf ratios in combination with variable 187Os/188Os ratios can now demonstrate the presence of residual carbonated eclogite components, either in the lithosphere or in the asthenospheric mantle. Finally, by combining geochemical and temporal constraints of Tertiary and Quaternary volcanism it becomes evident that CEVP volcanism in central and western Germany has resulted from compositionally distinct magmatic pulses that tap separate mantle sources. Although the presence of a mantle plume can neither be fully confirmed nor excluded, plume-like melt pulses which partially tap carbonated eclogite domains that interact to variable extents with the lithosphere provide a viable explanation for the temporal and compositional cyclicity of CEVP volcanism. Supplementary Information The online version contains supplementary material available at 10.1007/s00410-024-02137-w.
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Affiliation(s)
- Mike W. Jansen
- Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49B, 50674 Cologne, Germany
| | - Carsten Münker
- Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49B, 50674 Cologne, Germany
| | - Josua J. Pakulla
- Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49B, 50674 Cologne, Germany
| | - Eric Hasenstab-Dübeler
- Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49B, 50674 Cologne, Germany
| | - Christian S. Marien
- Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49B, 50674 Cologne, Germany
| | - Toni Schulz
- Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49B, 50674 Cologne, Germany
- Department für Lithosphärenforschung, Universität Wien, Josef-Holaubek 2 (UZA II), 1090 Vienna, Austria
| | - Maria Kirchenbaur
- Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49B, 50674 Cologne, Germany
- Institut für Geologie, Mineralogie, und Geophysik, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany
| | - Kathrin P. Schneider
- Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49B, 50674 Cologne, Germany
| | - Robin Tordy
- Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49B, 50674 Cologne, Germany
| | - Vera Schmitt
- Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49B, 50674 Cologne, Germany
| | - Frank Wombacher
- Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49B, 50674 Cologne, Germany
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Homrighausen S, Hoernle K, Hauff F, Hoyer PA, Haase KM, Geissler WH, Geldmacher J. Evidence for compositionally distinct upper mantle plumelets since the early history of the Tristan-Gough hotspot. Nat Commun 2023; 14:3908. [PMID: 37400438 DOI: 10.1038/s41467-023-39585-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 06/19/2023] [Indexed: 07/05/2023] Open
Abstract
Recent studies indicate that mantle plumes, which transfer material and heat from the earth's interior to its surface, represent multifaceted upwellings. The Tristan-Gough hotspot track (South Atlantic), which formed above a mantle plume, documents spatial geochemical zonation in two distinct sub-tracks since ~70 Ma. The origin and the sudden appearance of two distinct geochemical flavors is enigmatic, but could provide insights into the structural evolution of mantle plumes. Sr-Nd-Pb-Hf isotope data from the Late Cretaceous Rio Grande Rise and adjacent Jean Charcot Seamount Chain (South American Plate), which represent the counterpart of the older Tristan-Gough volcanic track (African Plate), extends the bilateral-zonation to ~100 Ma. Our results support recent numerical models, demonstrating that mantle plumes can split into distinct upper mantle conduits, and provide evidence that these plumelets formed at the plume head-to-plume tail transition. We attribute the plume zonation to sampling the geochemically-graded margin of the African Large Low-Shear-Velocity Province.
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Affiliation(s)
| | - Kaj Hoernle
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
- Kiel University, Institute of Geosciences, Kiel, Germany
| | - Folkmar Hauff
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Patrick A Hoyer
- Friedrich-Alexander-Universität Erlangen-Nürnberg, GeoZentrum Nordbayern, Erlangen, Germany
| | - Karsten M Haase
- Friedrich-Alexander-Universität Erlangen-Nürnberg, GeoZentrum Nordbayern, Erlangen, Germany
| | - Wolfram H Geissler
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Jörg Geldmacher
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
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Sehsah H, Furnes H, Pham LT, Eldosouky AM. Plume-MOR decoupling and the timing of India-Eurasia collision. Sci Rep 2022; 12:13349. [PMID: 35922451 PMCID: PMC9349248 DOI: 10.1038/s41598-022-16981-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 07/19/2022] [Indexed: 11/10/2022] Open
Abstract
The debatable timing of India-Eurasia collision is based on geologic, stratigraphic, kinematic, and tectonic evidence. However, the collision event disturbed persistent processes, and the timing of disturbance in such processes could determine the onset of India-Eurasia collision precisely. We use the longevity of Southeast Indian Ridge (SEIR)-Kerguelen mantle plume (KMP) interaction cycles along the Ninetyeast ridge (NER) as a proxy to determine the commencement of India-Eurasia collision. The geochemical signature of the KMP tail along the NER is predominantly that of long-term coupling cycles, that was perturbed once by a short-term decoupling cycle. The long-term coupling cycles are mainly of enriched mid-ocean ridge basalts (E-MORBs). The short-term decoupling cycle is mostly derived from two distinct sources, MOR and plume separately, whereas the KMP is still being on-axis. The onset of India-Eurasia collision led to continental materials recycling into the mantle; hence the abrupt enrichment in incompatible elements at ca. 55 Ma, the MOR-plume on-axis decoupling, and the abrupt slowdown in the northward drift of the Indian plate was induced by the onset of India-Eurasia collision, thereafter MOR-plume recoupled.
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Affiliation(s)
- Haytham Sehsah
- Geology Department, Faculty of Science, Damietta University, New Damietta, Damietta, 34517, Egypt.
| | - Harald Furnes
- Department of Earth Science, University of Bergen, Allegt. 41, 5007, Bergen, Norway
| | - Luan Thanh Pham
- Department of Geophysics, Faculty of Physics, University of Science, Vietnam National University, Hanoi, Vietnam
| | - Ahmed M Eldosouky
- Geology Department, Faculty of Science, Suez University, Suez, 43518, Egypt
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Closure of the Eastern Paleo-Asian Ocean: Constraints from the Age and Geochemistry of Early Permian Zhaojinggou Pluton in Inner Mongolia (North China). MINERALS 2022. [DOI: 10.3390/min12060738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The closing time of the Paleo-Asian Ocean and the tectonic evolution of the northern margin of the North China Craton are still controversial. The geochronology and geochemistry of the Zhaojinggou monzogranite pluton provide new constraints on the late Paleozoic tectonic evolution and the closure time of the Paleo-Asian Ocean in the southern Central Asian Orogenic Belt (CAOB). The monzogranite yielded a zircon U-Pb age of 286.7 ± 1.2 Ma. Due to the characteristics of low–moderate Mg# values (25.87–39.21), low Fe2O3T values (1.13–1.72), and A/CNK > 1, we show that the pluton is weak peraluminous, high in potassium calc–alkaline series, and displays the feature of S-type granite. The total REE content is low, the distribution curve is right dipping, and the LREE is enriched; the δEu average value is 1.32 (1.11–1.54). The granite presents relatively high (87Sr/86Sr)i values of 0.712345–0.713723, low εNd(t) values of −8.89–−8.21 (an average value of −8.56), and a TDM2 of 1718–1773 Ma. Furthermore, the zircon in situ Hf isotopic analysis shows 176Hf/177Hf ratios of 0.282342 to 0.282614, low εHf(t) values of −9.27–0.38 (mean −4.74), and a TDM2 of 1275–1887 Ma. Additionally, high field strength elements such as Nb, Ta, and Ti are depleted, and large ion lithophile elements, e.g., Rb, Ba, K, and Sr, are enriched. The above features of the Zhaojinggou monzogranite indicate that the pluton was derived from late Paleoproterozoic to Mesoproterozoic lower crustal mafic materials. By discussing the genesis and tectonic implications of the pluton massif, we propose that the Zhaojinggou monzogranite represents a magmatic event caused by the crustal–mantle interaction during the southward subduction of the eastern Paleo-Asian Ocean in the northern margin of the North China Craton during the Early Permian.
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Petrogenesis of Lava from Christmas Island, Northeast Indian Ocean: Implications for the Nature of Recycled Components in Non-Plume Intraplate Settings. GEOSCIENCES 2022. [DOI: 10.3390/geosciences12030118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Lava samples from the Christmas Island Seamount Province (CHRISP) record an extreme range in enriched mantle (EM) type Sr-Nd-Pb-Hf isotope signatures. Here we report osmium isotope data obtained on four samples from the youngest, Pliocene petit-spot phase (Upper Volcanic Series, UVS; ~4.4 Ma), and four samples from the earlier, Eocene (Lower Volcanic Series, LVS; ~40 Ma) shield building phase of Christmas Island. Osmium concentrations are low (5–82 ppt) with initial Os isotopic values (187Os/188Osi) ranging from (0.1230–0.1679). Along with additional new geochemical data (major and trace elements, Sr-Nd-Pb isotopes, olivine δ18O values), we demonstrate the following: (1) The UVS is consistent with melting of shallow Indian mid-ocean ridge basalt (MORB) mantle enriched with both lower continental crust (LCC) and subcontinental lithospheric mantle (SCLM) components; and (2) The LVS is consistent with recycling of SCLM components related to Gondwana break-up. The SCLM component has FOZO or HIMU like characteristics. One of the LVS samples has less radiogenic Os (γOs –3.4) and provides evidence for the presence of ancient SCLM in the source. The geochemistry of the Christmas Island lava series supports the idea that continental breakup causes shallow recycling of lithospheric and lower crustal components into the ambient MORB mantle.
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Neogene Alkali Basalts from Central Slovakia (Ostrá Lúka Lava Complex); Mineralogy and Geochemistry. MINERALS 2022. [DOI: 10.3390/min12020195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Ostrá Lúka basalts are a product of the final phase of Neogene volcanism in Central Slovakia. Their major and trace elements composition is alkaline, a feature confirmed by light rare earth elements (LREE) relative enrichment and some incompatible trace elements ratios. The basalts contain rare surrounded gabbro cumulates. Their peculiarity is a strong zonation of olivines and clinopyroxene. The significant zonation probably indicates a short stop of the melt at shallow depth. The Sr, Nd and Pb isotope compositions indicate an origin from a moderately depleted mantle source. The mineral and chemical composition of the basalts is similar to the Pannonian basin alkali basalts and the Western and Central Europe alkali basalts.
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7
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Thermochemical anomalies in the upper mantle control Gakkel Ridge accretion. Nat Commun 2021; 12:6962. [PMID: 34845208 PMCID: PMC8630051 DOI: 10.1038/s41467-021-27058-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 10/15/2021] [Indexed: 11/30/2022] Open
Abstract
Despite progress in understanding seafloor accretion at ultraslow spreading ridges, the ultimate driving force is still unknown. Here we use 40Ar/39Ar isotopic dating of mid-ocean ridge basalts recovered at variable distances from the axis of the Gakkel Ridge to provide new constraints on the spatial and temporal distribution of volcanic eruptions at various sections of an ultraslow spreading ridge. Our age data show that magmatic-dominated sections of the Gakkel Ridge spread at a steady rate of ~11.1 ± 0.9 mm/yr whereas amagmatic sections have a more widely distributed melt supply yielding ambiguous spreading rate information. These variations in spreading rate and crustal accretion correlate with locations of hotter thermochemical anomalies in the asthenosphere beneath the ridge. We conclude therefore that seafloor generation in ultra-slow spreading centres broadly reflects the distribution of thermochemical anomalies in the upper mantle.
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Li HY, Zhao RP, Li J, Tamura Y, Spencer C, Stern RJ, Ryan JG, Xu YG. Molybdenum isotopes unmask slab dehydration and melting beneath the Mariana arc. Nat Commun 2021; 12:6015. [PMID: 34650082 PMCID: PMC8517010 DOI: 10.1038/s41467-021-26322-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 09/23/2021] [Indexed: 11/09/2022] Open
Abstract
How serpentinites in the forearc mantle and subducted lithosphere become involved in enriching the subarc mantle source of arc magmas is controversial. Here we report molybdenum isotopes for primitive submarine lavas and serpentinites from active volcanoes and serpentinite mud volcanoes in the Mariana arc. These data, in combination with radiogenic isotopes and elemental ratios, allow development of a model whereby shallow, partially serpentinized and subducted forearc mantle transfers fluid and melt from the subducted slab into the subarc mantle. These entrained forearc mantle fragments are further metasomatized by slab fluids/melts derived from the dehydration of serpentinites in the subducted lithospheric slab. Multistage breakdown of serpentinites in the subduction channel ultimately releases fluids/melts that trigger Mariana volcanic front volcanism. Serpentinites dragged down from the forearc mantle are likely exhausted at >200 km depth, after which slab-derived serpentinites are responsible for generating slab melts. How the subducted oceanic lithosphere provides fluids and melts to flux the subarc mantle source of arc magmas is controversial. Here the authors use Mo and other isotopes to show serpentinites formed in both the forearc mantle and the subducted lithosphere contribute to generating arc magmas.
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Affiliation(s)
- Hong-Yan Li
- State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China. .,CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China. .,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 511458, China.
| | - Rui-Peng Zhao
- State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jie Li
- State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.,CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
| | - Yoshihiko Tamura
- Research Institute for Marine Geodynamics (IMG), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, 237-0061, Japan
| | - Christopher Spencer
- Department of Geological Sciences and Geological Engineering, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Robert J Stern
- Department of Geoscience, University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Jeffrey G Ryan
- School of Geosciences, University of South Florida, Tampa, FL, 33620, USA
| | - Yi-Gang Xu
- State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.,CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 511458, China
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9
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A subduction influence on ocean ridge basalts outside the Pacific subduction shield. Nat Commun 2021; 12:4757. [PMID: 34362917 PMCID: PMC8346520 DOI: 10.1038/s41467-021-25027-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 07/13/2021] [Indexed: 02/07/2023] Open
Abstract
The plate tectonic cycle produces chemically distinct mid-ocean ridge basalts and arc volcanics, with the latter enriched in elements such as Ba, Rb, Th, Sr and Pb and depleted in Nb owing to the water-rich flux from the subducted slab. Basalts from back-arc basins, with intermediate compositions, show that such a slab flux can be transported behind the volcanic front of the arc and incorporated into mantle flow. Hence it is puzzling why melts of subduction-modified mantle have rarely been recognized in mid-ocean ridge basalts. Here we report the first mid-ocean ridge basalt samples with distinct arc signatures, akin to back-arc basin basalts, from the Arctic Gakkel Ridge. A new high precision dataset for 576 Gakkel samples suggests a pervasive subduction influence in this region. This influence can also be identified in Atlantic and Indian mid-ocean ridge basalts but is nearly absent in Pacific mid-ocean ridge basalts. Such a hemispheric-scale upper mantle heterogeneity reflects subduction modification of the asthenospheric mantle which is incorporated into mantle flow, and whose geographical distribution is controlled dominantly by a "subduction shield" that has surrounded the Pacific Ocean for 180 Myr. Simple modeling suggests that a slab flux equivalent to ~13% of the output at arcs is incorporated into the convecting upper mantle.
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Zhong Y, Zhang GL, Jin QZ, Huang F, Wang XJ, Xie LW. Sub-basin scale inhomogeneity of mantle in the South China Sea revealed by magnesium isotopes. Sci Bull (Beijing) 2021; 66:740-748. [PMID: 36654448 DOI: 10.1016/j.scib.2020.12.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 11/30/2020] [Accepted: 11/30/2020] [Indexed: 01/20/2023]
Abstract
The South China Sea (SCS) is the largest extensional basin in the western Pacific and was formed after rifting of the Euro-Asian continental margin. The nature of its underlying mantle remains enigmatic due to the lack of sampling of the seafloor's igneous crust. The International Ocean Discovery Program Expedition 349 cored seafloor basalts of the southwestern (Site U1433) and eastern (Site U1431) SCS sub-basins. The recovered basalt samples exhibit different source lithologies and geochemistries. The Mg isotopic compositions of seafloor basalts from these sites were investigated to elucidate the origin of this large-scale mantle inhomogeneity. Results indicate that the Site U1431 basalts have a mantle-like average δ26Mg value of -0.27‰ ± 0.06‰ (2SD; n = 10). Together with inhomogeneous Sr-Nd-Pb-Hf isotopic compositions, the Site U1433 basalts have an average δ26Mg value (-0.20‰ ± 0.06‰; 2SD; n = 8) higher than those of the Site U1431 basalts and normal mantle. Their heavier Mg isotopic compositions and low 206Pb/204Pb ratios (~17.7) indicate that the Site U1433 basalts were affected by the re-melting of detached continental-arc lithosphere in the sub-ridge mantle. The coupling of Mg and Sr-Nd isotopes provides robust evidence that the mantle-like δ26Mg values of the Site U1431 basalts resulted from mixing between detached continental arc lithosphere and the nearby Hainan plume, with respective supra- and sub-normal δ26Mg values. From the perspective of Mg isotope, the mantles of the southwestern and eastern sub-basins are compositionally inhomogeneous, with their mantle evolutionary histories being distinct.
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Affiliation(s)
- Yuan Zhong
- Center of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Guo-Liang Zhang
- Center of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; Laboratory for Marine Geology, National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China.
| | - Qi-Zhen Jin
- CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China
| | - Fang Huang
- CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China
| | - Xiao-Jun Wang
- State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi'an 710069, China
| | - Lie-Wen Xie
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
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An Overview of the Geochemical Characteristics of Oceanic Carbonatites: New Insights from Fuerteventura Carbonatites (Canary Islands). MINERALS 2021. [DOI: 10.3390/min11020203] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The occurrence of carbonatites in oceanic settings is very rare if compared with their continental counterpart, having been reported only in Cape Verde and Canary Islands. This paper provides an overview of the main geochemical characteristics of oceanic carbonatites, around which many debates still exist regarding their petrogenesis. We present new data on trace elements in minerals and whole-rock, together with the first noble gases isotopic study (He, Ne, Ar) in apatite, calcite, and clinopyroxene from Fuerteventura carbonatites (Canary Islands). Trace elements show a similar trend as Cape Verde carbonatites, almost tracing the same patterns on multi-element and REE abundance diagrams. 3He/4He isotopic ratios of Fuerteventura carbonatites reflect a shallow (sub-continental lithospheric mantle, SCLM) He signature in their petrogenesis, and they clearly differ from Cape Verde carbonatites, i.e., fluids from a deep and low degassed mantle with a primitive plume-derived He signature are involved in their petrogenesis.
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Geochemical Variation of Miocene Basalts within Shikoku Basin: Magma Source Compositions and Geodynamic Implications. MINERALS 2020. [DOI: 10.3390/min11010025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Shikoku Basin is unique as being located within a trench-ridge-trench triple junction. Here, we report mineral compositions, major, trace-element, and Sr-Nd-Pb isotopic compositions of bulk-rocks from Sites C0012 (>18.9 Ma) and 1173 (13–15 Ma) of the Shikoku Basin. Samples from Sites C0012 and 1173 are tholeiitic in composition and display relative depletion in light rare earth elements (REEs) and enrichment in heavy REEs, generally similar to normal mid-ocean ridge basalts (N-MORB). Specifically, Site C0012 samples display more pronounced positive anomalies in Rb, Ba, K, Pb and Sr, and negative anomalies in Th, U, Nb, and Ta, as well as negative Nb relative to La and Th. Site 1173 basalts have relatively uniform Sr-Nd-Pb isotopic compositions, close to the end member of depleted mantle, while Site C0012 samples show slightly enriched Sr-Nd-Pb isotopic signature, indicating a possible involvement of enriched mantle 1 (EM1) and EM2 sources, which could be attributed to the metasomatism of the fluids released from the dehydrated subduction slab, but with the little involvement of subducted slab-derived sedimentary component. Additionally, the Shikoku Basin record the formation of the back-arc basin was a mantle conversion process from an island arc to a typical MORB. The formation of the Shikoku Basin is different from that of the adjacent Japan Sea and Parece Vela Basin, mainly in terms of the metasomatized subduction-related components, the nature of mantle source, and partial melting processes.
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Ancient helium and tungsten isotopic signatures preserved in mantle domains least modified by crustal recycling. Proc Natl Acad Sci U S A 2020; 117:30993-31001. [PMID: 33229590 DOI: 10.1073/pnas.2009663117] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Rare high-3He/4He signatures in ocean island basalts (OIB) erupted at volcanic hotspots derive from deep-seated domains preserved in Earth's interior. Only high-3He/4He OIB exhibit anomalous 182W-an isotopic signature inherited during the earliest history of Earth-supporting an ancient origin of high 3He/4He. However, it is not understood why some OIB host anomalous 182W while others do not. We provide geochemical data for the highest-3He/4He lavas from Iceland (up to 42.9 times atmospheric) with anomalous 182W and examine how Sr-Nd-Hf-Pb isotopic variations-useful for tracing subducted, recycled crust-relate to high 3He/4He and anomalous 182W. These data, together with data on global OIB, show that the highest-3He/4He and the largest-magnitude 182W anomalies are found only in geochemically depleted mantle domains-with high 143Nd/144Nd and low 206Pb/204Pb-lacking strong signatures of recycled materials. In contrast, OIB with the strongest signatures associated with recycled materials have low 3He/4He and lack anomalous 182W. These observations provide important clues regarding the survival of the ancient He and W signatures in Earth's mantle. We show that high-3He/4He mantle domains with anomalous 182W have low W and 4He concentrations compared to recycled materials and are therefore highly susceptible to being overprinted with low 3He/4He and normal (not anomalous) 182W characteristic of subducted crust. Thus, high 3He/4He and anomalous 182W are preserved exclusively in mantle domains least modified by recycled crust. This model places the long-term preservation of ancient high 3He/4He and anomalous 182W in the geodynamic context of crustal subduction and recycling and informs on survival of other early-formed heterogeneities in Earth's interior.
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Petrogenetic Constraints of Early Cenozoic Mafic Rocks in the Southwest Songliao Basin, NE China: Implications for the Genesis of Sandstone-Hosted Qianjiadian Uranium Deposits. MINERALS 2020. [DOI: 10.3390/min10111014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The tectonic inversion of the Songliao Basin during the Cenozoic may have played an important role in controlling the development of sandstone-type uranium deposits. The widely distributed mafic intrusions in the host sandstones of the Qianjiadian U ore deposits provided new insights to constrain the regional tectonic evolution and the genesis of the U mineralization. In this study, zircon U-Pb dating, whole-rock geochemistry, Sr-Nd-Pb isotope analysis, and mineral chemical compositions were presented for the mafic rocks from the Qianjiadian area. The mafic rocks display low SiO2 (44.91–52.05 wt.%), high TFe2O3 contents (9.97–16.46 wt.%), variable MgO (4.59–15.87 wt.%), and moderate K2O + Na2O (3.19–6.52 wt.%), and can be subdivided into AB group (including basanites and alkali olivine basaltic rocks) and TB group (mainly tholeiitic basaltic rocks). They are characterized by homogenous isotopic compositions (εNd (t) = 3.47–5.89 and 87Sr/86Sr = 0.7032–0.7042) and relatively high radiogenic 206Pb/204Pb (18.13–18.34) and Nb/U ratios (23.0–45.6), similar to the nearby Shuangliao basalts, suggesting a common asthenospheric origin enriched with slab-derived components prior to melting. Zircon U-Pb and previous Ar-Ar dating show that the AB group formed earlier (51–47 Ma) than the TB group (42–40 Ma). Compared to the TB group, the AB group has higher TiO2, Na2O, K2O, P2O5, Ce, and HREE contents and Ta/Yb and Sr/Yb ratios, which may have resulted from variable depth of partial melting in association with lithospheric thinning. Combined with previous research, the Songliao Basin experienced: (1) Eocene (~50–40 Ma) lithospheric thinning and crustal extension during which mafic rocks intruded into the host sandstones of the Qianjiadian deposit, (2) a tectonic inversion from extension to tectonic uplift attributed to the subduction of the Pacific Plate occurring at ~40 Ma, and (3) Oligo–Miocene (~40–10 Ma) tectonic uplift, which is temporally associated with U mineralization. Finally, the close spatial relation between mafic intrusions and the U mineralization, dike-related secondary reduction, and secondary oxidation of the mafic rocks in the Qianjiadian area suggest that Eocene mafic rocks and their alteration halo in the Songliao Basin may have played a role as a reducing barrier for the U mineralization.
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15
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Struve T, Pahnke K, Lamy F, Wengler M, Böning P, Winckler G. A circumpolar dust conveyor in the glacial Southern Ocean. Nat Commun 2020; 11:5655. [PMID: 33168803 PMCID: PMC7652835 DOI: 10.1038/s41467-020-18858-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 09/14/2020] [Indexed: 11/22/2022] Open
Abstract
The increased flux of soluble iron (Fe) to the Fe-deficient Southern Ocean by atmospheric dust is considered to have stimulated the net primary production and carbon export, thus promoting atmospheric CO2 drawdown during glacial periods. Yet, little is known about the sources and transport pathways of Southern Hemisphere dust during the Last Glacial Maximum (LGM). Here we show that Central South America (~24‒32°S) contributed up to ~80% of the dust deposition in the South Pacific Subantarctic Zone via efficient circum-Antarctic dust transport during the LGM, whereas the Antarctic Zone was dominated by dust from Australia. This pattern is in contrast to the modern/Holocene pattern, when South Pacific dust fluxes are thought to be primarily supported by Australian sources. Our findings reveal that in the glacial Southern Ocean, Fe fertilization critically relies on the dynamic interaction of changes in dust-Fe sources in Central South America with the circumpolar westerly wind system. Dust deposition brings iron that fuels ocean productivity, a connection impacting climate over geological time. Here the authors use sediment cores to show that in contrast to dynamics today, during the last glacial maximum westerly winds shuttled dust from Australia and South America around Antarctica and into the South Pacific.
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Affiliation(s)
- Torben Struve
- Marine Isotope Geochemistry, Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, 26129, Oldenburg, Germany.
| | - Katharina Pahnke
- Marine Isotope Geochemistry, Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, 26129, Oldenburg, Germany
| | - Frank Lamy
- Alfred Wegener Institute for Polar and Marine Research, 27568, Bremerhaven, Germany
| | - Marc Wengler
- Alfred Wegener Institute for Polar and Marine Research, 27568, Bremerhaven, Germany
| | - Philipp Böning
- Marine Isotope Geochemistry, Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, 26129, Oldenburg, Germany
| | - Gisela Winckler
- Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York, 10964, USA.,Department of Earth and Environmental Sciences, Columbia University, New York, New York, 10027, USA
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16
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Hafnium isotope constraints on the nature of the mantle beneath the Southern Lau basin (SW Pacific). Sci Rep 2020; 10:17476. [PMID: 33060785 PMCID: PMC7566480 DOI: 10.1038/s41598-020-74565-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 10/01/2020] [Indexed: 11/19/2022] Open
Abstract
New Hf isotope data provide new insights into the nature of the mantle beneath the southern Lau basin, adding new constraints on the displacement process of the Pacific mid-ocean ridge basalt (MORB)-type mantle by the Indian MORB-type mantle. The Hf isotopic ratios (176Hf/177Hf) of submarine lavas from the eastern Lau spreading center (ELSC) range from 0.283194 (εHf = 14.92) to 0.283212 (εHf = 15.54), with an average value of 0.283199 (εHf = 15.11) whereas those from the Valu Fa ridge (VFR) vary from 0.283221 (εHf = 15.88) to 0.283200 (εHf = 15.14), with an average of 0.283214 (15.61), indicating that ELSC lavas have a slightly more radiogenic Hf isotopic composition than VFR lavas. In contrast to the results from previous studies, the new Hf analyses combined with previous Nd isotope data clearly show that both VFR and ELSC have the distinct Hf–Nd isotope composition of the so-called DUPAL isotopic anomaly in the Indian MORB-type mantle. The DUPAL isotopic signature at VFR demonstrates for the first time that the inflow of the Indian MORB-type mantle has reached the southern tip of tectonic propagation in the southern Lau basin.
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17
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Richter M, Nebel O, Maas R, Mather B, Nebel-Jacobsen Y, Capitanio FA, Dick HJB, Cawood PA. An Early Cretaceous subduction-modified mantle underneath the ultraslow spreading Gakkel Ridge, Arctic Ocean. SCIENCE ADVANCES 2020; 6:6/44/eabb4340. [PMID: 33127673 PMCID: PMC7608816 DOI: 10.1126/sciadv.abb4340] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 09/14/2020] [Indexed: 06/11/2023]
Abstract
Earth's upper mantle, as sampled by mid-ocean ridge basalts (MORBs) at oceanic spreading centers, has developed chemical and isotopic heterogeneity over billions of years through focused melt extraction and re-enrichment by recycled crustal components. Chemical and isotopic heterogeneity of MORB is dwarfed by the large compositional spectrum of lavas at convergent margins, identifying subduction zones as the major site for crustal recycling into and modification of the mantle. The fate of subduction-modified mantle and if this heterogeneity transmits into MORB chemistry remains elusive. Here, we investigate the origin of upper mantle chemical heterogeneity underneath the Western Gakkel Ridge region in the Arctic Ocean through MORB geochemistry and tectonic plate reconstruction. We find that seafloor lavas from the Western Gakkel Ridge region mirror geochemical signatures of an Early Cretaceous, paleo-subduction zone, and conclude that the upper mantle can preserve a long-lived, stationary geochemical memory of past geodynamic processes.
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Affiliation(s)
- Marianne Richter
- Isotopia Laboratory, School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria 3800, Australia.
- School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria 3800, Australia
| | - Oliver Nebel
- Isotopia Laboratory, School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria 3800, Australia
- School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria 3800, Australia
| | - Roland Maas
- School of Earth Sciences, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Ben Mather
- School of Geosciences, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Yona Nebel-Jacobsen
- Isotopia Laboratory, School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria 3800, Australia
- School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria 3800, Australia
| | - Fabio A Capitanio
- School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria 3800, Australia
| | - Henry J B Dick
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543-1539, USA
| | - Peter A Cawood
- Isotopia Laboratory, School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria 3800, Australia
- School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria 3800, Australia
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18
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Boudoire G, Rizzo AL, Arienzo I, Di Muro A. Paroxysmal eruptions tracked by variations of helium isotopes: inferences from Piton de la Fournaise (La Réunion island). Sci Rep 2020; 10:9809. [PMID: 32555201 PMCID: PMC7300000 DOI: 10.1038/s41598-020-66260-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 05/04/2020] [Indexed: 11/09/2022] Open
Abstract
Helium (He) with its isotopes (3He, 4He) is a key tracer enabling the Earth's mantle and dynamics to be characterized. Enrichment in primordial helium (3He) has been detected in volcanic gases of numerous magmatic systems in different geodynamic settings. Despite past use to monitor volcano-tectonic unrest, temporal 3He/4He variability in volcanic emissions is still poorly constrained. Here, we investigate noble gas chemistry of Piton de la Fournaise hotspot volcano, where temporal fluctuations of 3He/4He in response to the eruptive activity have never been studied. We compare the 3He/4He signature of volcanic gases and fluid inclusions and we highlight analogous evolution of the 3He/4He signature in both during the last decades of eruptive activity (1990-2017), even during the same eruption. We show that the maximum enrichment in 3He is found in magmatic fluids that fed the most voluminous eruptions which culminated in caldera collapse events. We argue that this enrichment in 3He mostly reflects a greater contribution of magmatic fluids from a primitive component of the mantle plume. These results emphasize that He isotopes may provide warnings of increases in deep magmatic contributions that potentially herald paroxysmal eruptions, as documented here at Piton de la Fournaise (2007) and also at Kilauea (2018).
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Affiliation(s)
- G Boudoire
- Université Clermont Auvergne, CNRS, IRD, OPGC, Laboratoire Magmas et Volcans, 6 avenue Blaise Pascal, 63178, Aubière, France. .,Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, Via Ugo La Malfa 153, 90146, Palermo, Italy.
| | - A L Rizzo
- Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, Via Ugo La Malfa 153, 90146, Palermo, Italy.,Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Ferrara, 44121, Ferrara, Italy
| | - I Arienzo
- Istituto Nazionale Di Geofisica e Vulcanologia, Osservatorio Vesuviano, Via Diocleziano 328, 80124, Napoli, Italy
| | - A Di Muro
- Université de Paris, Institut de Physique du Globe de Paris, CNRS, F-75005, Paris, France.,Observatoire Volcanologique du Piton de la Fournaise, Institut de Physique du Globe de Paris, F-97418, La Plaine des Cafres, France
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Geochemical and Sr-Nd-Pb-Hf Isotopic Characteristics of Muchen Pluton in Southeast China, Constrain the Petrogenesis of Alkaline A-Type Magma. MINERALS 2020. [DOI: 10.3390/min10010080] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We present comprehensive petrological, major-trace element, in situ zircon U-Pb dating and Sr-Nd-Pb isotopic data for Muchen granitoid (western Zhejiang Province, Southeast China), to constrain the petrogenesis of alkaline A-type granites and the geodynamic setting of Southeast China in the Early Cretaceous. The Early Cretaceous Muchen quartz monzonite yielded zircon U-Pb crystallization ages of 111.3 ± 0.7 Ma and is metaluminous to weakly peraluminous with SiO2 contents ranging from 59 to 69 wt.%, and can be classified as alkaline A-type granitoid. The quartz monzonites have low (87Sr/86Sr)i values (0.7052 to 0.7061) and high εNd(t) values (−2.6 to −2.0), similar to nearby coeval mafic rocks that have been proposed to be derived from the enriched lithospheric mantle. The high Nb/Ta ratios (16.7 to 30.1, average 21.8) and low Nb/U ratios (as low as 3.5) indicate the involvement of slab-derived melt and fluids in this mantle. These geochemical properties of the Muchen quartz monzonites indicated that they might be from a phlogopite-bearing and rutile-rich subduction-modified subcontinental lithospheric mantle, and underwent strong fractional crystallization of olivine + orthopyroxene + plagioclase during magma ascent. The low Mg# values of these alkaline rocks (<30 mostly) may indicate a low-pressure source in a back-arc setting. The early Cretaceous alkaline granitoids in Southeast China are related to the continental back-arc setting caused by deep angle subduction of the paleo-Pacific plate.
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20
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Geochemistry and tectonic significance of late Paleoproterozoic A-type granites along the southern margin of the North China Craton. Sci Rep 2020; 10:86. [PMID: 31919370 PMCID: PMC6952446 DOI: 10.1038/s41598-019-56820-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 12/17/2019] [Indexed: 11/08/2022] Open
Abstract
The Longwangzhuang pluton is a typical example of Paleoproterozoic A-type granite intrusions at the southern margin of the North China Craton. This pluton is composed of arfvedsonite granite and minor aegirine-augite granites. Samples from both granite types display similar zircon U-Pb ages with 207U-206Pb ages of 1612 ± 19 Ma [mean square weighted deviation (MSWD) = 0.66] and 1609 ± 24 Ma (MSWD = 0.5), respectively. The granites exhibit similar high silica (SiO2 = 71.1-73.4 wt.%), high alkaline (Na2O + K2O = 8.10-9.26 wt.%, K2O/Na2O > 1), and low Al2O3 (11.8-12.8 wt. %) contents and metaluminous to weakly peraluminous bulk chemistry. The chemical variations of the Longwangzhuang pluton suggest the effects of mineral fractionation. In addition, all samples show typical characteristics of A-type granites, such as high 10000Ga/Al ratios (4.10-7.28), high FeOtot/(FeOtot + MgO) ratios (0.88-0.99), and high Zr (484-1082 ppm), Ce (201-560 ppm), and Y (78-156 ppm) contents. The εNd(t) values and the (206Pb/204Pb)t, (207Pb/204Pb)t, and (208Pb/204Pb)t ratios of the arfvedsonite granite samples vary from -4.6 to -5.3, 15.021 to 17.349, 15.241 to 15.472, and 33.206 to 36.905, respectively, and those for the aegirine-augite granite sample amount at -0.2, 14.421, 15.175, and 33.706. The distinct and variable Nd and Pb isotope values indicate the presence of heterogeneous protoliths. Based on its geochemistry, its low initial Pb isotope ratios, and its enrichment in Nd isotopes, we infer that the Longwangzhuang A-type granite is the partial melting product of basement rocks such as the Taihua Group gneisses accompanied by some involvement of juvenile material from the mantle. Together with published data from other Paleoproterozoic A-type granite plutons exposed at the southern margin of the craton, our findings suggest that these granites had a similar origin. Furthermore, geochemically, they can be divided into two groups: A2-type, which formed earlier (~1.8-1.6 Ga), and A1-type, which formed later (~1.6-1.5 Ga). Combining this information with the variations in whole-rock Nd and zircon Hf isotopic composition at ca. 1.6 Ga, we propose that tectonic transformation from post-orogenic to anorogenic magmatism occurred at the southern margin of the North China Craton at that time.
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Origin of Pumice in Sediments from the Middle Okinawa Trough: Constraints from Whole-Rock Geochemical Compositions and Sr-Nd-Pb Isotopes. JOURNAL OF MARINE SCIENCE AND ENGINEERING 2019. [DOI: 10.3390/jmse7120462] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Frequent volcanic activity has occurred in the Okinawa Trough (OT) during the late Quaternary, which attracted much attention to the origin of volcanic rocks. Pumice collected from the seafloor has been extensively investigated, whereas few studies paid attention to the pumice in the sediment. The geochemical compositions of pumice preserved in sediments generally provide insight into past volcanic activity and regional magmatism. Here, we present major and trace element compositions and Sr-Nd-Pb isotope data, together with the established age framework for pumice samples recovered from sediment core S9 in the middle OT (MOT) to investigate their possible formation. Compositionally, the S9 pumice samples are dacite and are characterized by relatively higher Sr (87Sr/86Sr = 0.70480–0.70502) and Pb (206Pb/204Pb = 18.321-18.436, 207Pb/204Pb = 15.622–15.624, and 208Pb/204Pb = 38.52–38.63) and lower Nd (143Nd/144Nd = 0.51272–0.51274) isotope compositions than basalts from the MOT. The geochemical compositions of pumice clasts from different layers of core S9 display no temporal variation trends and vary within narrow ranges. On the basis of the geochemical characteristics of S9 pumice samples, we infer that the parent magma of these samples might generate from hybrid magma through an extensive fractional crystallization process. The Indian Ocean MORB-type mantle was first metasomatized by the subducted Philippine Sea sediments to form the primitive magma; then, followed by assimilation of a small amount of lower crustal component occurred in the lower crust. The long-term magmatism and relatively consistent isotopic compositions indicate that a magma chamber might have existed in the lower crust of the MOT between 11.22 and 12.96 cal. ka BP.
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Constraining Mantle Heterogeneity beneath the South China Sea: A New Perspective on Magma Water Content. MINERALS 2019. [DOI: 10.3390/min9070410] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The nature of upper mantle is important to understand the evolution of the South China Sea (SCS); thus, we need better constrains on its mantle heterogeneity. Magma water concentration is a good indicator, but few data have been reported. However, the rarity of glass and melt inclusions and the special genesis for phenocrysts in SCS basalts present challenges to analyzing magmatic water content. Therefore, it is possible to estimate the water variations through the characteristics of partial melting and magma crystallization. We evaluated variations in Fe depletion, degree of melt fractions, and mantle source composition along the fossil spreading ridge (FSR) using SCS basalt data from published papers. We found that lava from the FSR 116.2° E, FSR 117.7° E, and non-FSR regions can be considered normal lava with normal water content; in contrast, lava from the FSR 117° E-carbonatite and 114.9–115.0° E basalts have higher water content and show evidence of strong Fe depletion during the fractional crystallization after elimination of the effects of plagioclase oversaturation. The enriched water in the 117° E-carbonatite basalts is contained in carbonated silicate melts, and that in the 114.9–115.0° E basalts results from mantle contamination with the lower continental crust. The lava from the 117° E-normal basalt has much lower water content because of the lesser influence of the Hainan plume. Therefore, there must be a mantle source compositional transition area between the southwestern and eastern sub-basins of the SCS, which have different mantle evolution histories. The mantle in the west is more affected by contamination with continental materials, while that in the east is more affected by the Hainan mantle plume.
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Shellnutt JG, Dostal J. Haida Gwaii (British Columbia, Canada): a Phanerozoic analogue of a subduction-unrelated Archean greenstone belt. Sci Rep 2019; 9:3251. [PMID: 30824832 PMCID: PMC6397315 DOI: 10.1038/s41598-019-39818-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 01/28/2019] [Indexed: 11/08/2022] Open
Abstract
Understanding the formation and evolution of Precambrian greenstone belts is hampered by gaps in the rock record and the uncertainty of the tectonic regime that was operating at the time. Thus identifying a modern analogue of a Precambrian greenstone belt can be problematic. In this paper we present geological, geochemical and petrological evidence outlining the case for Haida Gwaii (British Columbia, Canada) as a modern example of a greenstone belt. Haida Gwaii is comprised of two rift-related volcano-sedimentary sequences. The older (Early Triassic) Karmutsen volcanic sequence consists of subaqueous ultramafic-mafic volcanic rocks that are capped by marine carbonate and siliciclastic rocks. The younger (Paleogene) Masset bimodal volcanic sequence consists of tholeiitic and calc-alkaline basalt along with calc-alkaline silicic volcanic and intrusive rocks that are capped by epiclastic sandstones. The Karmutsen and Masset volcanic rocks have indistinguishable Sr-Nd-Pb isotopes demonstrating they were derived from a similar mantle source. Some of the Masset calc-alkaline rocks are compositionally similar to magnesian andesites (SiO2 = 56-64 wt%; Mg# = 0.50-0.64) that are typical of subduction-related Archean greenstone belts. We show that the calc-alkaline signature observed in the bimodal sequence of the Masset Formation is likely due to fractional crystallization of a tholeiitic parental magma under relatively oxidizing (ΔFMQ + 0.7) conditions indicating that a calc-alkaline signature is not prima facie evidence of a subduction setting. Given the geological and geochemical evidence, Haida Gwaii represents one of the best analogues of a modern subduction-unrelated Archean greenstone belt.
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Affiliation(s)
- J Gregory Shellnutt
- National Taiwan Normal University, Department of Earth Sciences, 88 Tingzhou Road Section 4, Taipei, 11677, Taiwan.
| | - Jaroslav Dostal
- Saint Mary's University, Department of Geology, 923 Robie Street, Halifax, NS, B3H 3C3, Canada
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24
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Ranaweera LV, Ota T, Moriguti T, Tanaka R, Nakamura E. Circa 1 Ga sub-seafloor hydrothermal alteration imprinted on the Horoman peridotite massif. Sci Rep 2018; 8:9887. [PMID: 29959384 PMCID: PMC6026181 DOI: 10.1038/s41598-018-28219-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 05/25/2018] [Indexed: 12/02/2022] Open
Abstract
The chemical compositions of the residues of the mantle melting that produces mid-ocean ridge basalt can be altered by fluid–rock interactions at spreading ridges and, possibly, during seawater penetration along bending-related faults in plates approaching trenches. This chemically modified rock, if subducted deeply and after long-term residence within the deep Earth, is a potential source of chemical heterogeneity in the mantle. Here, we demonstrate that peridotites from the Horoman massif preserve the chemical signatures of sub-seafloor hydrothermal (SSH) alteration at a mid-ocean ridge approximately one billion years ago. These rocks have evolved chemically subsequent to this SSH alteration; however, they retain the SSH-associated enrichments in fluid mobile elements and H2O despite their long-term residence within the mantle. Our results indicate that ancient SSH alteration resulting in the production of sulfide leads to Pb enrichment that could affect the present-day Pb isotopic evolution of the silicate earth. Evidence from the Horoman massif of the recycling of hydrous refractory domains into the mantle suggests that both the flux of H2O content into the mantle and the size of the mantle H2O reservoir are higher than have been estimated recently.
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Affiliation(s)
- Lalindra V Ranaweera
- Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University at Misasa, Tottori, 682-0193, Japan.,Department of Natural Resources, Faculty of Applied Sciences, Sabaragamuwa University of Sri Lanka, Belihuloya, Sri Lanka
| | - Tsutomu Ota
- Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University at Misasa, Tottori, 682-0193, Japan
| | - Takuya Moriguti
- Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University at Misasa, Tottori, 682-0193, Japan
| | - Ryoji Tanaka
- Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University at Misasa, Tottori, 682-0193, Japan
| | - Eizo Nakamura
- Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University at Misasa, Tottori, 682-0193, Japan.
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Yan Q, Shi X, Metcalfe I, Liu S, Xu T, Kornkanitnan N, Sirichaiseth T, Yuan L, Zhang Y, Zhang H. Hainan mantle plume produced late Cenozoic basaltic rocks in Thailand, Southeast Asia. Sci Rep 2018; 8:2640. [PMID: 29422658 PMCID: PMC5805767 DOI: 10.1038/s41598-018-20712-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 01/23/2018] [Indexed: 11/25/2022] Open
Abstract
Intraplate volcanism initiated shortly after the cessation of Cenozoic seafloor spreading in the South China Sea (SCS) region, but the full extent of its influence on the Indochina block has not been well constrained. Here we present major and trace element data and Sr-Nd-Pb-Hf isotope ratios of late Cenozoic basaltic lavas from the Khorat plateau and some volcanic centers in the Paleozoic Sukhothai arc terrane in Thailand. These volcanic rocks are mainly trachybasalts and basaltic trachyandesites. Trace element patterns and Sr-Nd-Pb-Hf isotopic compositions show that these alkaline volcanic lavas exhibit oceanic island basalt (OIB)-like characteristics with enrichments in both large-ion lithophile elements (LILE) and high field strength elements (HFSEs). Their mantle source is a mixture between a depleted Indian MORB-type mantle and an enriched mantle type 2 (EMII). We suggest that the post-spreading intraplate volcanism in the SCS region was induced by a Hainan mantle plume which spread westwards to the Paleozoic Sukhothai arc terrane.
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Affiliation(s)
- Quanshu Yan
- Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, SOA, Qingdao, 266061, China. .,Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266061, China.
| | - Xuefa Shi
- Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, SOA, Qingdao, 266061, China. .,Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266061, China.
| | - Ian Metcalfe
- School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia
| | - Shengfa Liu
- Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, SOA, Qingdao, 266061, China.,Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266061, China
| | - Taoyu Xu
- Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, SOA, Qingdao, 266061, China.,Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266061, China
| | - Narumol Kornkanitnan
- Marine and Coastal Resources Research and Development Center Upper Gulf of Thailand, 120/1 Bangyapraek, Meuang, Samut sakhon, 74000, Thailand
| | - Thanyapat Sirichaiseth
- Marine and Coastal Resources Research and Development Center Upper Gulf of Thailand, 120/1 Bangyapraek, Meuang, Samut sakhon, 74000, Thailand
| | - Long Yuan
- Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, SOA, Qingdao, 266061, China
| | - Ying Zhang
- Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, SOA, Qingdao, 266061, China
| | - Hui Zhang
- Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, SOA, Qingdao, 266061, China
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Su HM, Jiang SY, Zhang DY, Wu XK. Partial Melting of Subducted Sediments Produced Early Mesozoic Calc-alkaline Lamprophyres from Northern Guangxi Province, South China. Sci Rep 2017; 7:4864. [PMID: 28687743 PMCID: PMC5501806 DOI: 10.1038/s41598-017-05228-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 05/25/2017] [Indexed: 11/10/2022] Open
Abstract
There is growing agreement that subducted sediments recycled into the deep mantle could make a significant contribution to the generation of various mantle-derived rocks. However, solid evidence and examples to support this view are few, and whether or not the subducted sediments can act as the dominating material source for the magma is unclear. Here, we report a comprehensive geochemical study that demonstrates that the newly identified Early Mesozoic calc-alkaline lamprophyres in the northern Guangxi Province, southeastern Yangtze Block in South China were likely derived in large part from the partial melting of the subducted terrigenous sediments in the deep mantle. The investigated lamprophyres are SiO2-rich minettes, characterized by moderate TFeO and MgO and high Mg# (>70). The multi-element pattern shows a typical crustal-like signature, such as enrichments in large-ion lithophile elements (LILE) and light rare earth elements (LREE) with troughs in Nb-Ta, Ti and Eu and peaks in Th-U and Pb. These rocks also show sediment-like ratios of Nb/U, Nb/Th and Ce/Pb, together with extremely radiogenic 87Sr/86Sr (0.71499–0.71919), unradiogenic 143Nd/144Nd (0.51188–0.51195) and radiogenic 207Pb/204Pb (15.701–15.718) isotopic compositions.
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Affiliation(s)
- Hui-Min Su
- State Key Laboratory of Geological Processes and Mineral Resources, Collaborative Innovation Center for Exploration of Strategic Mineral Resources, Faculty of Earth Resources, China University of Geosciences, Wuhan, 430074, China
| | - Shao-Yong Jiang
- State Key Laboratory of Geological Processes and Mineral Resources, Collaborative Innovation Center for Exploration of Strategic Mineral Resources, Faculty of Earth Resources, China University of Geosciences, Wuhan, 430074, China. .,State Key Laboratory for Mineral Deposits Research, Department of Earth Sciences, Nanjing University, Nanjing, 210093, China.
| | - Dong-Yang Zhang
- State Key Laboratory of Geological Processes and Mineral Resources, Collaborative Innovation Center for Exploration of Strategic Mineral Resources, Faculty of Earth Resources, China University of Geosciences, Wuhan, 430074, China
| | - Xiang-Ke Wu
- Geological Survey Institute of Guangxi, Guangxi Bureau of Geology and Mineral Prospecting and Exploitation, Nanning, 530023, China
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Barry TL, Davies JH, Wolstencroft M, Millar IL, Zhao Z, Jian P, Safonova I, Price M. Whole-mantle convection with tectonic plates preserves long-term global patterns of upper mantle geochemistry. Sci Rep 2017; 7:1870. [PMID: 28500352 PMCID: PMC5431867 DOI: 10.1038/s41598-017-01816-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 04/04/2017] [Indexed: 11/29/2022] Open
Abstract
The evolution of the planetary interior during plate tectonics is controlled by slow convection within the mantle. Global-scale geochemical differences across the upper mantle are known, but how they are preserved during convection has not been adequately explained. We demonstrate that the geographic patterns of chemical variations around the Earth’s mantle endure as a direct result of whole-mantle convection within largely isolated cells defined by subducting plates. New 3D spherical numerical models embedded with the latest geological paleo-tectonic reconstructions and ground-truthed with new Hf-Nd isotope data, suggest that uppermost mantle at one location (e.g. under Indian Ocean) circulates down to the core-mantle boundary (CMB), but returns within ≥100 Myrs via large-scale convection to its approximate starting location. Modelled tracers pool at the CMB but do not disperse ubiquitously around it. Similarly, mantle beneath the Pacific does not spread to surrounding regions of the planet. The models fit global patterns of isotope data and may explain features such as the DUPAL anomaly and long-standing differences between Indian and Pacific Ocean crust. Indeed, the geochemical data suggests this mode of convection could have influenced the evolution of mantle composition since 550 Ma and potentially since the onset of plate tectonics.
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Affiliation(s)
- T L Barry
- Department of Geology, University of Leicester, Leicester, LE1 7RH, UK.
| | - J H Davies
- School of Earth and Ocean Sciences, Cardiff University, Cardiff, CF10 3AT, Wales, UK
| | - M Wolstencroft
- JBA Risk Management, Broughton Hall, Skipton, North Yorkshire, BD23 3AE, UK
| | - I L Millar
- NERC Isotope Geosciences Laboratory, British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK
| | - Z Zhao
- School of Earth Science and Resources, China University of Geosciences, Beijing, 100083, China
| | - P Jian
- Beijing SHRIMP Centre, Institute of Geology, Chinese Academy of Geological Sciences, Beijing, 100037, China
| | - I Safonova
- Sobolev Institute of Geology and Mineralogy SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - M Price
- School of Earth and Ocean Sciences, Cardiff University, Cardiff, CF10 3AT, Wales, UK
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Wang W, Zhang S, Yu Q, Lin Y, Yang N, Han W, Zhang J. Hydrothermal liquefaction of high protein microalgae via clay material catalysts. RSC Adv 2017. [DOI: 10.1039/c7ra08311d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Clay catalysts efficiently liquefy the Spirulina into petroleum like biocrude.
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Affiliation(s)
- Wenjia Wang
- School of Environment and Natural Resources
- Renmin University of China
- Beijing
- PR China
| | - Shengdi Zhang
- School of Environment and Natural Resources
- Renmin University of China
- Beijing
- PR China
| | - Qi Yu
- School of Environment and Natural Resources
- Renmin University of China
- Beijing
- PR China
| | - Yutong Lin
- School of Environment and Natural Resources
- Renmin University of China
- Beijing
- PR China
| | - Nianzi Yang
- School of Environment and Natural Resources
- Renmin University of China
- Beijing
- PR China
| | - Wei Han
- School of Environment and Natural Resources
- Renmin University of China
- Beijing
- PR China
| | - Jinglai Zhang
- School of Environment and Natural Resources
- Renmin University of China
- Beijing
- PR China
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29
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Zhang GL, Li C. Interactions of the Greater Ontong Java mantle plume component with the Osbourn Trough. Sci Rep 2016; 6:37561. [PMID: 27869235 PMCID: PMC5116616 DOI: 10.1038/srep37561] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 11/01/2016] [Indexed: 11/09/2022] Open
Abstract
The Ontong Java-Manihiki-Hikurangi plateau (OJMHP) is considered to have originated from a starting mantle plume, and have been rifted apart by two spreading ridges. However, the ages of these spreading ridges and their possible interactions with the presumed mantle plume are unclear. The Manihiki-Hikurangi plateau has been rifted apart by the Osbourn Trough which formed the southwestern Pacific crust to the east of the Tonga-Kermadec trench. Here we report Pb-Hf-Os isotopes of the basaltic crust (Site U1365 of IODP Expedition 329) formed by the Osbourn Trough. Linear regression of Re-Os isotopes results in an age of 103.7 ± 2.3 Ma for Site U1365 basalts, indicating that the Manihiki-Hikurangi plateau was rifted apart by the Osbourn Trough with a spreading rate of ~190 mm/yr. The superfast spreading rate supports the Osbourn as an abandoned segment of the early Pacific spreading ridge, which initially overlapped with the giant starting plume. Moreover, the Pb-Hf isotopes of some of Site U1365 basalts show distinct differences from those of the Pacific mid-ocean ridge basalts, while they are similar to the basalts of the Ontong Java and Manihiki plateaus. We suggest that the OJMHP mantle plume components has been involved by the Osbourn spreading center.
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Affiliation(s)
- Guo-Liang Zhang
- Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.,Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266061, China
| | - Chao Li
- Institute of Geology Chinese Academy of Geological Sciences, Beijing 100037, China
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30
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Abstract
A consideration of the use made of selected papers in physical oceanography, magnetic stratigraphy, and earthquake distribution traces the development of the ideas necessary to the theory of plate tectonics, the presently accepted theory to explain geologic processes. The citation analysis undertaken of some thirty significant papers supports a previously proposed revolution m earth science thinking in the early 1970s. Al though the theory has enjoyed considerable success in unravell ing 'young' geology, its application to older rocks, particularly those that make up the continents, has been less successful. This may be because the 'revolution' has constrained earth scientists to think that present-day lateral crustal motions have been dominant throughout Earth history.
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Affiliation(s)
- A.P.W. Hodder
- Department of Earth Sciences, University of Waikato, Hamilton, New Zealand
| | - C. Balog
- Information Section, Ministry of Agriculture and Fisheries, Wellington, New Zealand
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31
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Abstract
The magmatic activity (0-16 Ma) in Iceland is linked to a deep mantle plume that has been active for the past 62 My. Icelandic and northeast Atlantic basalts contain variable proportions of two enriched components, interpreted as recycled oceanic crust supplied by the plume, and subcontinental lithospheric mantle derived from the nearby continental margins. A restricted area in southeast Iceland--and especially the Öræfajökull volcano--is characterized by a unique enriched-mantle component (EM2-like) with elevated (87)Sr/(86)Sr and (207)Pb/(204)Pb. Here, we demonstrate through modeling of Sr-Nd-Pb abundances and isotope ratios that the primitive Öræfajökull melts could have assimilated 2-6% of underlying continental crust before differentiating to more evolved melts. From inversion of gravity anomaly data (crustal thickness), analysis of regional magnetic data, and plate reconstructions, we propose that continental crust beneath southeast Iceland is part of ∼350-km-long and 70-km-wide extension of the Jan Mayen Microcontinent (JMM). The extended JMM was marginal to East Greenland but detached in the Early Eocene (between 52 and 47 Mya); by the Oligocene (27 Mya), all parts of the JMM permanently became part of the Eurasian plate following a westward ridge jump in the direction of the Iceland plume.
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32
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Helium and lead isotopes reveal the geochemical geometry of the Samoan plume. Nature 2014; 514:355-8. [PMID: 25318524 DOI: 10.1038/nature13794] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Accepted: 08/15/2014] [Indexed: 11/08/2022]
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33
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Mougel B, Agranier A, Hemond C, Gente P. A highly unradiogenic lead isotopic signature revealed by volcanic rocks from the East Pacific Rise. Nat Commun 2014; 5:4474. [PMID: 25027032 DOI: 10.1038/ncomms5474] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 06/20/2014] [Indexed: 11/09/2022] Open
Abstract
Radiogenic isotopes in oceanic basalts provide a window into the different geochemical components defining the composition of Earth's mantle. Here we report the discovery of a novel geochemical signature in volcanic glasses sampled at a sub-kilometre scale along the East Pacific Rise between 15°37'N and 15°47'N. The most striking aspect of this signature is its unradiogenic lead ((206)Pb/(204)Pb=17.49, (207)Pb/(204)Pb=15.46 and (208)Pb/(204)Pb=36.83). In conjunction with enriched Sr, Nd and Hf signatures, Pb isotopes depict mixing lines that trend away from any known mantle end-members. We suggest that this unradiogenic lead component sampled by magmatic melts corresponds to a novel upper mantle reservoir that should be considered in the Pb isotope budget of the bulk silicate Earth. Major, trace element and isotope compositions are suggestive of an ancient and lower continental origin for this unradiogenic lead component, possibly sulphide-bearing pyroxenites that were preserved even after prolonged stirring within the ambient upper mantle.
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Affiliation(s)
- Berengere Mougel
- Laboratoire Domaines Océaniques, UMR6538, IUEM, 29280 Plouzané, France
| | - Arnaud Agranier
- Laboratoire Domaines Océaniques, UMR6538, IUEM, 29280 Plouzané, France
| | - Christophe Hemond
- Laboratoire Domaines Océaniques, UMR6538, IUEM, 29280 Plouzané, France
| | - Pascal Gente
- Laboratoire Domaines Océaniques, UMR6538, IUEM, 29280 Plouzané, France
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Miller H, Croudace IW, Bull JM, Cotterill CJ, Dix JK, Taylor RN. A 500 year sediment lake record of anthropogenic and natural inputs to Windermere (English Lake District) using double-spike lead isotopes, radiochronology, and sediment microanalysis. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:7254-7263. [PMID: 24902065 DOI: 10.1021/es5008998] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A high-resolution record of pollution is preserved in recent sediments from Windermere, the largest lake in the English Lake District. Data derived from X-ray core scanning (validated against wavelength dispersive X-ray fluorescence), radiochronological techniques ((210)Pb and (137)Cs) and ultrahigh precision, double-spike mass spectrometry for lead isotopes are combined to decipher the anthropogenic inputs to the lake. The sediment record suggests that while most element concentrations have been stable, there has been a significant increase in lead, zinc, and copper concentrations since the 1930s. Lead isotope down-core variations identify three major contributory sources of anthropogenic (industrial) lead, comprising gasoline lead, coal combustion lead (most likely source is coal-fired steam ships), and lead derived from Carboniferous Pb-Zn mineralization (mining activities). Periods of metal workings do not correlate with peaks in heavy metals due to the trapping efficiency of up-system lakes in the catchment. Heavy metal increases could be due to flood-induced metal inwash after the cessation of mining and the weathering of bedrock in the catchment. The combination of sediment analysis techniques used provides new insights into the pollutant depositional history of Windermere and could be similarly applied to other lake systems to determine the timing and scale of anthropogenic inputs.
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Affiliation(s)
- Helen Miller
- Ocean and Earth Science, University of Southampton, National Oceanography Centre , European Way, Southampton, SO14 3ZH, U.K
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35
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Petrogenesis of Italian Alkaline Lavas Deduced from Pb-Sr-Nd Isotope Relationships. ACTA ACUST UNITED AC 2013. [DOI: 10.1029/gm095p0253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2023]
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36
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Cretaceous Basalts in Madagascar and the Transition Between Plume and Continental Lithosphere Mantle Sources. ACTA ACUST UNITED AC 2013. [DOI: 10.1029/gm100p0095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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37
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Dziewonski AM, Forte AM, Su W, Woodward RL. Seismic Tomography and Geodynamics. RELATING GEOPHYSICAL STRUCTURES AND PROCESSES: THE JEFFREYS VOLUME 2013. [DOI: 10.1029/gm076p0067] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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38
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The Influence of Mantle Plumes in Generation of Indian Oceanic Crust. ACTA ACUST UNITED AC 2013. [DOI: 10.1029/gm070p0057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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39
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Hotspots: The First 25 Years. ACTA ACUST UNITED AC 2013. [DOI: 10.1029/gm043p0001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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40
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Sharma M. Siberian Traps. LARGE IGNEOUS PROVINCES: CONTINENTAL, OCEANIC, AND PLANETARY FLOOD VOLCANISM 2013. [DOI: 10.1029/gm100p0273] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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41
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Woodward RL, Forte AM, Su WJ, Dziewonski AM. Constraints on the Large-Scale Structure of the Earth's Mantle. EVOLUTION OF THE EARTH AND PLANETS 2013. [DOI: 10.1029/gm074p0089] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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42
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Perfit MR, Chadwick WW. Magmatism at Mid-Ocean Ridges: Constraints from Volcanological and Geochemical Investigations. FAULTING AND MAGMATISM AT MID-OCEAN RIDGES 2013. [DOI: 10.1029/gm106p0059] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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43
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Cheng Q, Park KH, Macdougall JD, Zindler A, Lugmair GW, Staudigel H, Hawkins J, Lonsdale P. Isotopic Evidence for a Hotspot Origin of the Louisville Seamount Chain. SEAMOUNTS, ISLANDS, AND ATOLLS 2013. [DOI: 10.1029/gm043p0283] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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44
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Mcnutt MK, Fischer KM. The South Pacific Superswell. SEAMOUNTS, ISLANDS, AND ATOLLS 2013. [DOI: 10.1029/gm043p0025] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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45
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Schilling JG, Hanan BB, McCully B, Kingsley RH, Fontignie D. Influence of the Sierra Leone mantle plume on the equatorial Mid-Atlantic Ridge: A Nd-Sr-Pb isotopic study. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94jb00337] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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46
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Ray TW, Anderson DL. Spherical disharmonies in the Earth sciences and the spatial solution: Ridges, hotspots, slabs, geochemistry and tomography correlations. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94jb00340] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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47
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Rogers NW, Hawkesworth CJ, Ormerod DS. Late Cenozoic basaltic magmatism in the Western Great Basin, California and Nevada. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94jb02738] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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48
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Smith WHF, Staudigel H, Watts AB, Pringle MS. The Magellan seamounts: Early Cretaceous record of the South Pacific isotopic and thermal anomaly. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jb094ib08p10501] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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49
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Garfunkel Z, Anderson CA, Schubert G. Mantle circulation and the lateral migration of subducted slabs. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jb091ib07p07205] [Citation(s) in RCA: 213] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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50
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Vroon PZ, van Bergen MJ, White WM, Varekamp JC. Sr-Nd-Pb isotope systematics of the Banda Arc, Indonesia: Combined subduction and assimilation of continental material. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/93jb01716] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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