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Liu J, Palin RM, Mitchell RN, Liu Z, Zhang J, Li Z, Cheng C, Zhang H. Archaean multi-stage magmatic underplating drove formation of continental nuclei in the North China Craton. Nat Commun 2024; 15:6231. [PMID: 39043649 PMCID: PMC11266541 DOI: 10.1038/s41467-024-50435-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Accepted: 07/05/2024] [Indexed: 07/25/2024] Open
Abstract
The geodynamic processes that formed Earth's earliest continents are intensely debated. Particularly, the transformation from ancient crustal nuclei into mature Archaean cratons is unclear, primarily owing to the paucity of well-preserved Eoarchaean-Palaeoarchaean 'protocrust'. Here, we report a newly identified Palaeoarchaean continental fragment-the Baishanhu nucleus-in northeastern North China Craton. U-Pb geochronology shows that this nucleus preserves five major magmatic events during 3.6-2.5 Ga. Geochemistry and zircon Lu-Hf isotopes reveal ancient 4.2-3.8 Ga mantle extraction ages, as well as later intraplate crustal reworking. Crustal architecture and zircon Hf-O isotopes indicate that proto-North China first formed in a stagnant/squishy lid geodynamic regime characterised by plume-related magmatic underplating. Such cratonic growth and maturation were prerequisites for the emergence of plate tectonics. Finally, these data suggest that North China was part of the Sclavia supercraton and that the Archaean onset of subduction occurred asynchronously worldwide.
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Affiliation(s)
- Jin Liu
- College of Earth Sciences, Jilin University, Changchun, China
- Department of Earth Sciences, University of Oxford, Oxford, UK
| | - Richard M Palin
- Department of Earth Sciences, University of Oxford, Oxford, UK.
| | - Ross N Mitchell
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Zhenghong Liu
- College of Earth Sciences, Jilin University, Changchun, China
- Key Laboratory of Mineral Resources Evaluation in Northeast Asia, Ministry of Natural Resources, Changchun, China
| | - Jian Zhang
- Department of Earth Sciences, The University of Hong Kong, Hong Kong, China
| | - Zhongshui Li
- College of Exploration and Geomatics Engineering, Changchun Institute of Technology, Changchun, China
| | - Changquan Cheng
- School of Earth Sciences and Engineering, Sun Yat-sen University, Zhuhai, China
| | - Hongxiang Zhang
- College of Earth Sciences, Jilin University, Changchun, China
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Tang M, Liu X, Chen K. High Mg# of the continental crust explained by calc-alkaline differentiation. Natl Sci Rev 2023; 10:nwac258. [PMID: 36875781 PMCID: PMC9976743 DOI: 10.1093/nsr/nwac258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 11/10/2022] [Accepted: 11/10/2022] [Indexed: 11/16/2022] Open
Abstract
We used compiled geochemical data to investigate the mechanisms that control Mg# (molar ratio of Mg/(Mg + FeT)) in andesitic arc lavas. We find that andesites from mature continental arcs with crustal thickness of >45 km have systematically higher Mg# than those from oceanic arcs with crustal thickness of <30 km. The elevated Mg# in continental arc lavas results from strong Fe depletion during high-pressure differentiation favored in thick crusts. This proposal is reinforced by our compiled melting/crystallization experiment data. We show that the Mg# characteristics of continental arc lavas match that of the continental crust. These findings suggest that the formation of many high-Mg# andesites and the continental crust may not require slab-melt/peridotite interactions. Instead, the high Mg# of the continental crust can be explained by intracrustal calc-alkaline differentiation processes in magmatic orogens.
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Affiliation(s)
- Ming Tang
- Key Laboratory of Orogenic Belt and Crustal Evolution, Ministry of Education; School of Earth and Space Sciences, Peking University, Beijing 100871, China
| | - Xuanyu Liu
- Key Laboratory of Orogenic Belt and Crustal Evolution, Ministry of Education; School of Earth and Space Sciences, Peking University, Beijing 100871, China
| | - Kang Chen
- State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China
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Huang B, Johnson TE, Wilde SA, Polat A, Fu D, Kusky T. Coexisting divergent and convergent plate boundary assemblages indicate plate tectonics in the Neoarchean. Nat Commun 2022; 13:6450. [PMID: 36307406 PMCID: PMC9616927 DOI: 10.1038/s41467-022-34214-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 10/11/2022] [Indexed: 11/25/2022] Open
Abstract
The coexistence of divergent (spreading ridge) and convergent (subduction zone) plate boundaries at which lithosphere is respectively generated and destroyed is the hallmark of plate tectonics. Here, we document temporally- and spatially-associated Neoarchean (2.55–2.51 Ga) rock assemblages with mid-ocean ridge and supra-subduction-zone origins from the Angou Complex, southern North China Craton. These assemblages record seafloor spreading and contemporaneous subduction initiation and mature arc magmatism, respectively, analogous to modern divergent and convergent plate boundary processes. Our results provide direct evidence for lateral plate motions in the late Neoarchean, and arguably the operation of plate tectonics, albeit with warmer than average Phanerozoic subduction geotherms. Further, we surmise that plate tectonic processes played an important role in shaping Earth’s surficial environments during the Neoarchean and Paleoproterozoic. This study reports coexisting Neoarchean divergent and convergent plate boundary rock assemblages, providing new evidence for the operation of plate tectonics 2.55–2.51 billion years ago; and also suggests the subduction zone was warm then.
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Affiliation(s)
- Bo Huang
- Badong National Observation and Research Station for Geohazards, State Key Laboratory of Geological Processes and Mineral Resources, Center for Global Tectonics, School of Earth Sciences, China University of Geosciences, Wuhan, 430074, China.
| | - Tim E Johnson
- School of Earth and Planetary Sciences, The Institute for Geoscience Research, Curtin University, Perth, WA, 6102, Australia
| | - Simon A Wilde
- School of Earth and Planetary Sciences, The Institute for Geoscience Research, Curtin University, Perth, WA, 6102, Australia
| | - Ali Polat
- School of the Environment, University of Windsor, Windsor, ON, N9B 3P4, Canada
| | - Dong Fu
- Badong National Observation and Research Station for Geohazards, State Key Laboratory of Geological Processes and Mineral Resources, Center for Global Tectonics, School of Earth Sciences, China University of Geosciences, Wuhan, 430074, China
| | - Timothy Kusky
- Badong National Observation and Research Station for Geohazards, State Key Laboratory of Geological Processes and Mineral Resources, Center for Global Tectonics, School of Earth Sciences, China University of Geosciences, Wuhan, 430074, China.
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3He/4He Signature of Magmatic Fluids from Telica (Nicaragua) and Baru (Panama) Volcanoes, Central American Volcanic Arc. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12094241] [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
Constraining the magmatic 3He/4He signature of fluids degassed from a magmatic system is crucial for making inferences on its mantle source. This is especially important in arc volcanism, where variations in the composition of the wedge potentially induced by slab sediment fluids must be distinguished from the effects of magma differentiation, degassing, and crustal contamination. The study of fluid inclusions (FIs) trapped in minerals of volcanic rocks is becoming an increasingly used methodology in geochemical studies that integrates the classical study of volcanic and geothermal fluids. Here, we report on the first noble gas (He, Ne, Ar) concentrations and isotopic ratios of FI in olivine (Ol) and pyroxene (Px) crystals separated from eruptive products of the Telica and Baru volcanoes, belonging to the Nicaraguan and Panamanian arc-segments of Central America Volcanic arc (CAVA). FIs from Telica yield air corrected 3He/4He (Rc/Ra) of 7.2–7.4 Ra in Ol and 6.1–7.3 in Px, while those from Baru give 7.1–8.0 Ra in Ol and 4.2–5.8 Ra in Px. After a data quality check and a comparison with previous 3He/4He measurements carried out on the same volcanoes and along CAVA, we constrained a magmatic Rc/Ra signature of 7.5 Ra for Telica and of 8.0 Ra for Baru, both within the MORB range (8 ± 1 Ra). These 3He/4He differences also reflect variations in the respective arc-segments, which cannot be explained by radiogenic 4He addition due to variable crust thickness, as the mantle beneath Nicaragua and Panama is at about 35 and 30 km, respectively. We instead highlight that the lowest 3He/4He signature observed in the Nicaraguan arc segment reflects a contamination of the underlying wedge by slab sediment fluids. Rc/Ra values up to 9.0 Ra are found at Pacaya volcano in Guatemala, where the crust is 45 km thick, while a 3He/4He signature of about 8.0 Ra was measured at Turrialba volcano in Costa Rica, which is similar to that of Baru, and reflects possible influence of slab melting, triggered by a change in subduction conditions and the contemporary subduction of the Galapagos hot-spot track below southern Costa Rica and western Panama.
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Petrogenesis of Early Cretaceous High-Mg Adakitic Pluton in the North Lhasa Block, Tibet Plateau: Implications for the Tethyan Orogeny. MINERALS 2022. [DOI: 10.3390/min12020213] [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
Late Mesozoic igneous rocks from the north Lhasa block record the Neo-Tethyan orogeny in the southern Tibet Plateau. This study presents geochronological and geochemical data of Bieruozecuo quartz diorite pluton in the northern margin of the Lhasa block to constrain its petrogenesis and tectonic implications. The LA–ICP–MS zircon U–Pb geochronology of quartz diorites shows that the emplacement occurs at ca. 114–116 Ma, belonging to the products of Early Cretaceous magmatic activities. The high concentrations of TiO2, MgO, and MnO, together with SiO2 vs K2O and A/NK vs A/CNK diagrams, all suggest that the Bieruozecuo quartz diorites are meta-aluminous and high-potassium calc-alkaline rocks. Their high Sr and low Y and Yb contents, as well as high Sr/Y and La/Yb ratios, are consistent with the typical adakitic rocks. The REE patterns show a large distribution of compositions, which have LREE, while HREE are buffered, along with large ratios of (La/Yb)N, as well as high values of K2O/Na2O, Mg#, Cr, and Ni, all of which imply the partial melting of a delaminated lower crust, without obvious fractional crystallization during the magma ascending and emplacement. This study suggests that, with the closure of the Bangonghu–Nujiang Tethys Ocean Basin, the post-collisional extension of the north Lhasa block will have started no later than ca. 114–116 Ma. Combined with the previous studies, our new data demonstrates that the partial melting of the delaminated lower crust, in a post-collisional setting, may be the main mechanism responsible for the ca. 116–82 Ma adakitic magmatism in the north Lhasa block.
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Gianni GM, Navarrete CR. Catastrophic slab loss in southwestern Pangea preserved in the mantle and igneous record. Nat Commun 2022; 13:698. [PMID: 35121740 PMCID: PMC8817029 DOI: 10.1038/s41467-022-28290-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 01/11/2022] [Indexed: 11/16/2022] Open
Abstract
The Choiyoi Magmatic Province represents a major episode of silicic magmatism in southwestern Pangea in the mid-Permian-Triassic, the origin of which remains intensely debated. Here, we integrate plate-kinematic reconstructions and the lower mantle slab record beneath southwestern Pangea that provide clues on late Paleozoic-Mesozoic subducting slab configurations. Also, we compile geochronological information and analyze geochemical data using tectono-magmatic discrimination diagrams. We demonstrate that this magmatic event resulted from a large-scale slab loss. This is supported by a paleogeographic coincidence between a reconstructed 2,800-3,000-km-wide slab gap and the Choiyoi Magmatic Province and geochemical data indicating a slab break-off fingerprint in the latter. The slab break-off event is compatible with Permian paleogeographic modifications in southwestern Pangea. These findings render the Choiyoi Magmatic Province the oldest example of a geophysically constrained slab loss event and open new avenues to assess the geodynamic setting of silicic large igneous provinces back to the late Paleozoic. The origin of the Permian-Triassic Choiyoi silicic large igneous province (SLIP) is assessed by linking the igneous record, plate-kinematic reconstructions, and the deep mantle. This study suggests an origin related to a massive slab loss in Pangea.
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The formation of tonalitic and granodioritic melt from Venusian basalt. Sci Rep 2022; 12:1652. [PMID: 35102296 PMCID: PMC8803830 DOI: 10.1038/s41598-022-05745-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 01/17/2022] [Indexed: 11/09/2022] Open
Abstract
The crust of Venus is composed of the low lying volcanic planitiae and the elevated, deformed tesserae. It is thought that the tesserae may be composed of silicic igneous rocks and that it may resemble proto-continental crust. The initial development of terrestrial continental crust is likely due to melting and deformation of primitive mafic crust via mantle-plume upwelling and collisional plate processes. Unlike Earth, the lithosphere of Venus is not divided into plates and therefore evolved continental crust, if present, developed primarily by melting of pre-existing mafic crust. Here, we report the results of high pressure equilibrium partial melting experiments using a parental composition similar to the basalt measured at the Venera 14 landing site in order to determine if silicic melts can be generated. It was found that at pressures of 1.5 GPa and 2.0 GPa and temperatures of 1080 °C, 1090 °C, and 1285 °C that tonalitic and granodioritic melts can be generated. The experimental results indicate that silicic rocks may be able to form in the crust of Venus providing the thermal regime is suitable and that the lower crust is basaltic. The implication is that the older, thicker regions of Venusian crust may be partially composed of silicic igneous rocks.
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Adakites, High-Nb Basalts and Copper–Gold Deposits in Magmatic Arcs and Collisional Orogens: An Overview. GEOSCIENCES 2022. [DOI: 10.3390/geosciences12010029] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Adakites are Y- and Yb-depleted, SiO2- and Sr-enriched rocks with elevated Sr/Y and La/Yb ratios originally thought to represent partial melts of subducted metabasalt, based on their association with the subduction of young (<25 Ma) and hot oceanic crust. Later, adakites were found in arc segments associated with oblique, slow and flat subduction, arc–transform intersections, collision zones and post-collisional extensional environments. New models of adakite petrogenesis include the melting of thickened and delaminated mafic lower crust, basalt underplating of the continental crust and high-pressure fractionation (amphibole ± garnet) of mantle-derived, hydrous mafic melts. In some cases, adakites are associated with Nb-enriched (10 ppm < Nb < 20 ppm) and high-Nb (Nb > 20 ppm) arc basalts in ancient and modern subduction zones (HNBs). Two types of HNBs are recognized on the basis of their geochemistry. Type I HNBs (Kamchatka, Honduras) share N-MORB-like isotopic and OIB-like trace element characteristics and most probably originate from adakite-contaminated mantle sources. Type II HNBs (Sulu arc, Jamaica) display high-field strength element enrichments in respect to island-arc basalts coupled with enriched, OIB-like isotopic signatures, suggesting derivation from asthenospheric mantle sources in arcs. Adakites and, to a lesser extent, HNBs are associated with Cu–Au porphyry and epithermal deposits in Cenozoic magmatic arcs (Kamchatka, Phlippines, Indonesia, Andean margin) and Paleozoic-Mesozoic (Central Asian and Tethyan) collisional orogens. This association is believed to be not just temporal and structural but also genetic due to the hydrous (common presence of amphibole and biotite), highly oxidized (>ΔFMQ > +2) and S-rich (anhydrite in modern Pinatubo and El Chichon adakite eruptions) nature of adakite magmas. Cretaceous adakites from the Stanovoy Suture Zone in Far East Russia contain Cu–Ag–Au and Cu–Zn–Mo–Ag alloys, native Au and Pt, cupriferous Ag in association witn barite and Ag-chloride. Stanovoy adakites also have systematically higher Au contents in comparison with volcanic arc magmas, suggesting that ore-forming hydrothermal fluids responsible for Cu–Au(Mo–Ag) porphyry and epithermal mineralization in upper crustal environments could have been exsolved from metal-saturated, H2O–S–Cl-rich adakite magmas. The interaction between depleted mantle peridotites and metal-rich adakites appears to be capable of producing (under a certain set of conditions) fertile sources for HNB melts connected with some epithermal Au (Porgera) and porphyry Cu–Au–Mo (Tibet, Iran) mineralized systems in modern and ancient subduction zones.
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Yang S, Humayun M, Salters VJM. Elemental constraints on the amount of recycled crust in the generation of mid-oceanic ridge basalts (MORBs). SCIENCE ADVANCES 2020; 6:eaba2923. [PMID: 32637603 PMCID: PMC7319763 DOI: 10.1126/sciadv.aba2923] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 05/14/2020] [Indexed: 06/11/2023]
Abstract
Mid-oceanic ridge basalts (MORBs) are depleted in incompatible elements, but ridge segments far from mantle plumes frequently erupt chemically enriched MORBs (E-MORBs). Two major explanations of E-MORBs are that these basalts are generated by the melting of entrained recycled crust (pyroxenite) beneath ridges or by the melting of refertilized peridotites. These two hypotheses can be discriminated with compatible element abundances from Sc to Ge, here termed the ScGe elements. Here, we demonstrate that E-MORBs have systematically lower Ge/Si and Sc contents and slightly higher Fe/Mn and Nb/Ta ratios than depleted MORBs (D-MORBs) due to the mixing of low-degree pyroxenite melts. The Ge/Si ratio is a new tracer that effectively discriminates between melts derived from peridotite sources and melts derived from mixed pyroxenite-peridotite sources. These new data are used to estimate the distribution of pyroxenite in the mantle sources of global MORB segments.
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Affiliation(s)
- Shuying Yang
- National High Magnetic Field Laboratory and Department of Earth, Ocean and Atmospheric Science, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310, USA
| | - Munir Humayun
- National High Magnetic Field Laboratory and Department of Earth, Ocean and Atmospheric Science, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310, USA
| | - Vincent J. M. Salters
- National High Magnetic Field Laboratory and Department of Earth, Ocean and Atmospheric Science, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310, USA
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No evidence for high-pressure melting of Earth's crust in the Archean. Nat Commun 2019; 10:5559. [PMID: 31804503 PMCID: PMC6895241 DOI: 10.1038/s41467-019-13547-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 10/23/2019] [Indexed: 11/11/2022] Open
Abstract
Much of the present-day volume of Earth’s continental crust had formed by the end of the Archean Eon, 2.5 billion years ago, through the conversion of basaltic (mafic) crust into sodic granite of tonalite, trondhjemite and granodiorite (TTG) composition. Distinctive chemical signatures in a small proportion of these rocks, the so-called high-pressure TTG, are interpreted to indicate partial melting of hydrated crust at pressures above 1.5 GPa (>50 km depth), pressures typically not reached in post-Archean continental crust. These interpretations significantly influence views on early crustal evolution and the onset of plate tectonics. Here we show that high-pressure TTG did not form through melting of crust, but through fractionation of melts derived from metasomatically enriched lithospheric mantle. Although the remaining, and dominant, group of Archean TTG did form through melting of hydrated mafic crust, there is no evidence that this occurred at depths significantly greater than the ~40 km average thickness of modern continental crust. Some of Earth’s earliest continental crust has been previously inferred to have formed from partial melting of hydrated mafic crust at pressures above 1.5 GPa (more than 50 km deep), pressures typically not reached in post-Archean continental crust. Here, the authors show that such high pressure signatures can result from melting of mantle sources rather than melting of crust, and they suggest there is a lack of evidence that Earth’s earliest crust melted at depths significantly below 40 km.
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Petrogenetic Study of the Multiphase Chibougamau Pluton: Archaean Magmas Associated with Cu–Au Magmato-Hydrothermal Systems. MINERALS 2019. [DOI: 10.3390/min9030174] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The Chibougamau pluton is a Neoarchean multiphase intrusion that is related to Cu–Au porphyry-style deposits. In Archean greenstone belts, porphyries are marginal and poorly documented mineralizations. Such deposits are, however, important in the Chibougamau area, where the main historical mining camp (Central Camp) is a magmato-hydrothermal system. Understanding such systems requires documenting the related magmatic rocks. This contribution focuses on the petrogenesis of the Chibougamau pluton to elucidate how the intrusion participated in Cu and Au mineralized systems. Using field descriptions, whole-rock analyses, and petrographic observations, we describe the source, emplacement mechanism, and chemical evolution of the Chibougamau pluton. The Chibougamau pluton is a TTD (tonalite-trondhjemite-diorite) suite that contains more K than most plutons of similar age. This suite was produced from a heterogeneous source; i.e., a hydrated basalt and possibly a metasomatized mantle. These are rare (and thus prospective) characteristics for an Archean intrusion. In addition, differentiation may have been sufficiently prolonged in the diorite phase to concentrate metals and fluids in the evolved magma. These magmatic constraints must now be tested against a renewed understanding of the Cu-dominated mineralized systems of the Chibougamau area.
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Nebel O, Capitanio FA, Moyen JF, Weinberg RF, Clos F, Nebel-Jacobsen YJ, Cawood PA. When crust comes of age: on the chemical evolution of Archaean, felsic continental crust by crustal drip tectonics. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:rsta.2018.0103. [PMID: 30275165 PMCID: PMC6189554 DOI: 10.1098/rsta.2018.0103] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/10/2018] [Indexed: 05/18/2023]
Abstract
The secular evolution of the Earth's crust is marked by a profound change in average crustal chemistry between 3.2 and 2.5 Ga. A key marker for this change is the transition from Archaean sodic granitoid intrusions of the tonalite-trondhjemite-granodiorite (TTG) series to potassic (K) granitic suites, akin (but not identical) to I-type granites that today are associated with subduction zones. It remains poorly constrained as to how and why this change was initiated and if it holds clues about the geodynamic transition from a pre-plate tectonic mode, often referred to as stagnant lid, to mobile plate tectonics. Here, we combine a series of proposed mechanisms for Archaean crustal geodynamics in a single model to explain the observed change in granitoid chemistry. Numeric modelling indicates that upper mantle convection drives crustal flow and subsidence, leading to profound diversity in lithospheric thickness with thin versus thick proto-plates. When convecting asthenospheric mantle interacts with lower lithosphere, scattered crustal drips are created. Under increasing P-T conditions, partial melting of hydrated meta-basalt within these drips produces felsic melts that intrude the overlying crust to form TTG. Dome structures, in which these melts can be preserved, are a positive diapiric expression of these negative drips. Transitional TTG with elevated K mark a second evolutionary stage, and are blends of subsided and remelted older TTG forming K-rich melts and new TTG melts. Ascending TTG-derived melts from asymmetric drips interact with the asthenospheric mantle to form hot, high-Mg sanukitoid. These melts are small in volume, predominantly underplated, and their heat triggered melting of lower crustal successions to form higher-K granites. Importantly, this evolution operates as a disseminated process in space and time over hundreds of millions of years (greater than 200 Ma) in all cratons. This focused ageing of the crust implies that compiled geochemical data can only broadly reflect geodynamic changes on a global or even craton-wide scale. The observed change in crustal chemistry does mark the lead up to but not the initiation of modern-style subduction.This article is part of a discussion meeting issue 'Earth dynamics and the development of plate tectonics'.
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Affiliation(s)
- O Nebel
- School of Earth, Atmosphere and Environment, Monash University, Clayton, 3800 Victoria, Australia
| | - F A Capitanio
- School of Earth, Atmosphere and Environment, Monash University, Clayton, 3800 Victoria, Australia
| | - J-F Moyen
- Laboratoire Magmas et Volcans, Université de Lyon, UJM-UCA-CNRS-IRD, 23 rue Dr. Paul Michelon, 42023 Saint Etienne, France
| | - R F Weinberg
- School of Earth, Atmosphere and Environment, Monash University, Clayton, 3800 Victoria, Australia
| | - F Clos
- School of Earth, Atmosphere and Environment, Monash University, Clayton, 3800 Victoria, Australia
| | | | - P A Cawood
- School of Earth, Atmosphere and Environment, Monash University, Clayton, 3800 Victoria, Australia
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Ge R, Zhu W, Wilde SA, Wu H. Remnants of Eoarchean continental crust derived from a subducted proto-arc. SCIENCE ADVANCES 2018; 4:eaao3159. [PMID: 29487901 PMCID: PMC5817928 DOI: 10.1126/sciadv.aao3159] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Accepted: 01/11/2018] [Indexed: 06/08/2023]
Abstract
Eoarchean [3.6 to 4.0 billion years ago (Ga)] tonalite-trondhjemite-granodiorite (TTG) is the major component of Earth's oldest remnant continental crust, thereby holding the key to understanding how continental crust originated and when plate tectonics started in the early Earth. TTGs are mostly generated by partial melting of hydrated mafic rocks at different depths, but whether this requires subduction remains enigmatic. Recent studies show that most Archean TTGs formed at relatively low pressures (≤1.5 GPa) and do not require subduction. We report a suite of newly discovered Eoarchean tonalitic gneisses dated at ~3.7 Ga from the Tarim Craton, northwestern China. These rocks are probably the oldest high-pressure TTGs so far documented worldwide. Thermodynamic and trace element modeling demonstrates that the parent magma may have been generated by water-fluxed partial melting of moderately enriched arc-like basalts at 1.8 to 1.9 GPa and 800° to 830°C, indicating an apparent geothermal gradient (400° to 450°C GPa-1) typical for hot subduction zones. They also locally record geochemical evidence for magma interaction with a mantle wedge. Accordingly, we propose that these high-pressure TTGs were generated by partial melting of a subducted proto-arc during arc accretion. Our model implies that modern-style plate tectonics was operative, at least locally, at ~3.7 Ga and was responsible for generating some of the oldest continental nuclei.
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Affiliation(s)
- Rongfeng Ge
- State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093, P.R. China
- Department of Applied Geology, Curtin University, G.P.O. Box U1987, Perth, Western Australia 6845, Australia
| | - Wenbin Zhu
- State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093, P.R. China
| | - Simon A. Wilde
- Department of Applied Geology, Curtin University, G.P.O. Box U1987, Perth, Western Australia 6845, Australia
| | - Hailin Wu
- State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093, P.R. China
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Jia S, Wang E, Fu J, Men Y. Rare Earth Element–Trace-Element Geochemistry and Metallogenesis of the Wenzhangzi Au-Polymetallic Deposit in Western Liaoning Province, China. ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2018. [DOI: 10.1007/s13369-017-2744-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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Paleozoic–Mesozoic Porphyry Cu(Mo) and Mo(Cu) Deposits within the Southern Margin of the Siberian Craton: Geochemistry, Geochronology, and Petrogenesis (a Review). MINERALS 2016. [DOI: 10.3390/min6040125] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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16
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Jia X, Zhu X, Zhai M, Zhao Y, Zhang H, Wu J, Liu T. Late Mesoarchean crust growth event: evidence from the ca. 2.8 Ga granodioritic gneisses of the Xiaoqinling area, southern North China Craton. Sci Bull (Beijing) 2016. [DOI: 10.1007/s11434-016-1094-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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17
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Volcanic–plutonic parity and the differentiation of the continental crust. Nature 2015; 523:301-7. [DOI: 10.1038/nature14584] [Citation(s) in RCA: 134] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 05/18/2015] [Indexed: 11/08/2022]
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18
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Partial melting of deeply subducted eclogite from the Sulu orogen in China. Nat Commun 2014; 5:5604. [PMID: 25517619 PMCID: PMC4284643 DOI: 10.1038/ncomms6604] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Accepted: 10/20/2014] [Indexed: 11/20/2022] Open
Abstract
We report partial melting of an ultrahigh pressure eclogite in the Mesozoic Sulu orogen, China. Eclogitic migmatite shows successive stages of initial intragranular and grain boundary melt droplets, which grow into a three-dimensional interconnected intergranular network, then segregate and accumulate in pressure shadow areas and then merge to form melt channels and dikes that transport magma to higher in the lithosphere. Here we show, using zircon U–Pb dating and petrological analyses, that partial melting occurred at 228–219 Myr ago, shortly after peak metamorphism at 230 Myr ago. The melts and residues are complimentarily enriched and depleted in light rare earth element (LREE) compared with the original rock. Partial melting of deeply subducted eclogite is an important process in determining the rheological structure and mechanical behaviour of subducted lithosphere and its rapid exhumation, controlling the flow of deep lithospheric material, and for generation of melts from the upper mantle, potentially contributing to arc magmatism and growth of continental crust. Natural examples of eclogite-derived migmatite were previously unknown. Here, the authors show evidence of high-pressure melting of eclogite in the Sulu orogen of China, and suggest the melts represent an exhumed example of flow channels in the lower crust, possibly a source of syn-exhumation magmas.
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Zhao ZF, Dai LQ, Zheng YF. Postcollisional mafic igneous rocks record crust-mantle interaction during continental deep subduction. Sci Rep 2013; 3:3413. [PMID: 24301173 PMCID: PMC3849635 DOI: 10.1038/srep03413] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 11/14/2013] [Indexed: 11/10/2022] Open
Abstract
Findings of coesite and microdiamond in metamorphic rocks of supracrustal protolith led to the recognition of continental subduction to mantle depths. The crust-mantle interaction is expected to take place during subduction of the continental crust beneath the subcontinental lithospheric mantle wedge. This is recorded by postcollisional mafic igneous rocks in the Dabie-Sulu orogenic belt and its adjacent continental margin in the North China Block. These rocks exhibit the geochemical inheritance of whole-rock trace elements and Sr-Nd-Pb isotopes as well as zircon U-Pb ages and Hf-O isotopes from felsic melts derived from the subducted continental crust. Reaction of such melts with the overlying wedge peridotite would transfer the crustal signatures to the mantle sources for postcollisional mafic magmatism. Therefore, postcollisonal mafic igneous rocks above continental subduction zones are an analog to arc volcanics above oceanic subduction zones, providing an additional laboratory for the study of crust-mantle interaction at convergent plate margins.
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Affiliation(s)
- Zi-Fu Zhao
- 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
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Park J, Levin V, Brandon M, Lees J, Peyton V, Gordeev E, Ozerov A. A Dangling Slab, Amplified Arc Volcanism, Mantle Flow and Seismic Anisotropy in the Kamchatka Plate Corner. PLATE BOUNDARY ZONES 2013. [DOI: 10.1029/gd030p0295] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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21
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Brown M, Rushmer T, Sawyer EW. Introduction to Special Section: Mechanisms and Consequences of Melt Segregation From Crustal Protoliths. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/95jb01253] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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Beard JS. Experimental, geological, and geochemical constraints on the origins of low-K silicic magmas in oceanic arcs. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/95jb00861] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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23
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Rapp RP. Amphibole-out phase boundary in partially melted metabasalt, its control over liquid fraction and composition, and source permeability. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/95jb00913] [Citation(s) in RCA: 146] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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24
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Statistical geochemistry reveals disruption in secular lithospheric evolution about 2.5 Gyr ago. Nature 2012; 485:490-3. [PMID: 22622575 DOI: 10.1038/nature11024] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 03/05/2012] [Indexed: 11/08/2022]
Abstract
The Earth has cooled over the past 4.5 billion years (Gyr) as a result of surface heat loss and declining radiogenic heat production. Igneous geochemistry has been used to understand how changing heat flux influenced Archaean geodynamics, but records of systematic geochemical evolution are complicated by heterogeneity of the rock record and uncertainties regarding selection and preservation bias. Here we apply statistical sampling techniques to a geochemical database of about 70,000 samples from the continental igneous rock record to produce a comprehensive record of secular geochemical evolution throughout Earth history. Consistent with secular mantle cooling, compatible and incompatible elements in basalts record gradually decreasing mantle melt fraction through time. Superimposed on this gradual evolution is a pervasive geochemical discontinuity occurring about 2.5 Gyr ago, involving substantial decreases in mantle melt fraction in basalts, and in indicators of deep crustal melting and fractionation, such as Na/K, Eu/Eu* (europium anomaly) and La/Yb ratios in felsic rocks. Along with an increase in preserved crustal thickness across the Archaean/Proterozoic boundary, these data are consistent with a model in which high-degree Archaean mantle melting produced a thick, mafic lower crust and consequent deep crustal delamination and melting--leading to abundant tonalite-trondhjemite-granodiorite magmatism and a thin preserved Archaean crust. The coincidence of the observed changes in geochemistry and crustal thickness with stepwise atmospheric oxidation at the end of the Archaean eon provides a significant temporal link between deep Earth geochemical processes and the rise of atmospheric oxygen on the Earth.
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Zhao Z, Zheng Y. Remelting of subducted continental lithosphere: Petrogenesis of Mesozoic magmatic rocks in the Dabie-Sulu orogenic belt. ACTA ACUST UNITED AC 2009. [DOI: 10.1007/s11430-009-0134-8] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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26
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Crustal growth at ∼2.5 Ga in the North China Craton: evidence from whole-rock Nd and zircon Hf isotopes in the Huai’an gneiss terrane. Sci Bull (Beijing) 2009. [DOI: 10.1007/s11434-009-0288-y] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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27
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Tatsumi Y, Shukuno H, Tani K, Takahashi N, Kodaira S, Kogiso T. Structure and growth of the Izu-Bonin-Mariana arc crust: 2. Role of crust-mantle transformation and the transparent Moho in arc crust evolution. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007jb005121] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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29
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Yan Q, Chen J, Wang Z, Yan Z, Wang T, Li Q, Zhang Z, Jiang C. Zircon U-Pb and geochemical analyses for leucocratic intrusive rocks in pillow lavas in the Danfeng Group, north Qinling Mountains, China. ACTA ACUST UNITED AC 2008. [DOI: 10.1007/s11430-007-0144-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Tsuchiya N, Kanisawa S. Early Cretaceous Sr-rich silicic magmatism by slab melting in the Kitakami Mountains, northeast Japan. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/94jb00458] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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31
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Wei D, Xia B, Zhou G, Yan J, Wang R, Zhong L. Geochemistry and Sr-Nd isotope characteristics of tonalites in Zêtang, Tibet: New evidence for intra-Tethyan subduction. ACTA ACUST UNITED AC 2007. [DOI: 10.1007/s11430-007-0034-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Moyen JF, Stevens G. Experimental constraints on TTG petrogenesis: Implications for Archean geodynamics. ARCHEAN GEODYNAMICS AND ENVIRONMENTS 2006. [DOI: 10.1029/164gm11] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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Shchipansky A, Samsonov A, Bibikova E, Babarina I, Konilov A, Krylov K, Slabunov A, Bogina M. 2.8 Ga Boninite-Hosting Partial Suprasubduction Zone Ophiolite Sequences from the North Karelian Greenstone Belt, NE Baltic Shield, Russia. PRECAMBRIAN OPHIOLITES AND RELATED ROCKS 2004. [DOI: 10.1016/s0166-2635(04)13014-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Kincaid C, Griffiths RW. Laboratory models of the thermal evolution of the mantle during rollback subduction. Nature 2003; 425:58-62. [PMID: 12955138 DOI: 10.1038/nature01923] [Citation(s) in RCA: 197] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2002] [Accepted: 07/21/2003] [Indexed: 11/09/2022]
Abstract
The subduction of oceanic lithosphere plays a key role in plate tectonics, the thermal evolution of the mantle and recycling processes between Earth's interior and surface. Information on mantle flow, thermal conditions and chemical transport in subduction zones come from the geochemistry of arc volcanoes, seismic images and geodynamic models. The majority of this work considers subduction as a two-dimensional process, assuming limited variability in the direction parallel to the trench. In contrast, observationally based models increasingly appeal to three-dimensional flow associated with trench migration and the sinking of oceanic plates with a translational component of motion (rollback). Here we report results from laboratory experiments that reveal fundamental differences in three-dimensional mantle circulation and temperature structure in response to subduction with and without a rollback component. Without rollback motion, flow in the mantle wedge is sluggish, there is no mass flux around the plate and plate edges heat up faster than plate centres. In contrast, during rollback subduction flow is driven around and beneath the sinking plate, velocities increase within the mantle wedge and are focused towards the centre of the plate, and the surface of the plate heats more along the centreline.
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Affiliation(s)
- C Kincaid
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island 02882, USA.
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Stern RJ, Fouch MJ, Klemperer SL. An overview of the Izu-Bonin-Mariana subduction factory. INSIDE THE SUBDUCTION FACTORY 2003. [DOI: 10.1029/138gm10] [Citation(s) in RCA: 183] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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38
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Kelemen PB, Rilling JL, Parmentier EM, Mehl L, Hacker BR. Thermal structure due to solid-state flow in the mantle wedge beneath arcs. INSIDE THE SUBDUCTION FACTORY 2003. [DOI: 10.1029/138gm13] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Tatsumi Y. Some constraints on arc magma genesis. INSIDE THE SUBDUCTION FACTORY 2003. [DOI: 10.1029/138gm12] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Kelemen PB, Yogodzinski GM, Scholl DW. Along-strike variation in the Aleutian Island Arc: Genesis of high Mg# andesite and implications for continental crust. INSIDE THE SUBDUCTION FACTORY 2003. [DOI: 10.1029/138gm11] [Citation(s) in RCA: 176] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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41
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Gaetani GA, Grove TL. Experimental constraints on melt generation in the mantle wedge. INSIDE THE SUBDUCTION FACTORY 2003. [DOI: 10.1029/138gm07] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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42
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Tatsumi Y, Kogiso T. The subduction factory: its role in the evolution of the Earth’s crust and mantle. ACTA ACUST UNITED AC 2003. [DOI: 10.1144/gsl.sp.2003.219.01.03] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractSubduction zones are major sites of magmatism on the Earth. Dehydration processes and associated element transport, which take place in both the subducting lithosphere and the down-dragged hydrated peridotite layer at the base of the mantle wedge, are largely responsible for the following characteristics common to most subduction zones: (1) the presence of dual volcanic chains within a single volcanic arc; (2) the negative correlation between the volcanic arc width and the subduction angle; (3) selective enrichment of particular incompatible trace elements; and (4) systematic across-arc variations in incompatible trace element concentrations. The occurrence of two types of andesites, calcalkalic and tholeiitic, typifies magmatism in subduction zones. Examination of geochemical characteristics of those andesites in the NE Japan arc and bulk continental crust reveals marked compositional similarity between calc-alkalic andesites and continental crust. One of the principal mechanisms of generation of calc-alkalic andesites, at least those on the NE Japan arc, is the mixing of two magmas, having basaltic and felsic compositions and being derived from partial melting of the mantle and the overriding basaltic crust, respectively. It may be thus suggested that this process would also have contributed greatly to continental crust formation. If this is the case, then the melting residue after extraction of felsic melts should be removed and delaminated from the initial crust into the mantle in order to form ‘andesitic’ crust compositions. These processes cause accumulation in the deep mantle of residual materials, such as delaminated crust materials and dehydrated, compositionally modified subducted oceanic crusts and sediments. Geochemical modelling suggests that such residual components have evolved to form enriched mantle reservoirs.
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Affiliation(s)
- Yoshiyuki Tatsumi
- Institute for Frontier Research on Earth Evolution (IFREE), Japan Marine Science and Technology Center (JAMSTEC)
Yokosuka 237-0061, Japan
| | - Tetsu Kogiso
- Institute for Frontier Research on Earth Evolution (IFREE), Japan Marine Science and Technology Center (JAMSTEC)
Yokosuka 237-0061, Japan
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Foley S, Tiepolo M, Vannucci R. Growth of early continental crust controlled by melting of amphibolite in subduction zones. Nature 2002; 417:837-40. [PMID: 12075348 DOI: 10.1038/nature00799] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
It is thought that the first continental crust formed by melting of either eclogite or amphibolite, either at subduction zones or on the underside of thick oceanic crust. However, the observed compositions of early crustal rocks and experimental studies have been unable to distinguish between these possibilities. Here we show a clear contrast in trace-element ratios of melts derived from amphibolites and those from eclogites. Partial melting of low-magnesium amphibolite can explain the low niobium/tantalum and high zirconium/samarium ratios in melts, as required for the early continental crust, whereas the melting of eclogite cannot. This indicates that the earliest continental crust formed by melting of amphibolites in subduction-zone environments and not by the melting of eclogite or magnesium-rich amphibolites in the lower part of thick oceanic crust. Moreover, the low niobium/tantalum ratio seen in subduction-zone igneous rocks of all ages is evidence that the melting of rutile-eclogite has never been a volumetrically important process.
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Affiliation(s)
- Stephen Foley
- Institut für Geologische Wissenschaften, Universität Greifswald, F.L. Jahnstrasse 17a, D-17487 Greifswald, Germany.
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Adakite-type sodium-rich rocks in Awulale Mountain of west Tianshan: Significance for the vertical growth of continental crust. CHINESE SCIENCE BULLETIN-CHINESE 2001. [DOI: 10.1007/bf02900429] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Ducea M. The California Arc: Thick Granitic Batholiths, Eclogitic Residues, Lithospheric-Scale Thrusting, and Magmatic Flare-Ups. ACTA ACUST UNITED AC 2001. [DOI: 10.1130/1052-5173(2001)011<0004:tcatgb>2.0.co;2] [Citation(s) in RCA: 268] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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46
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The recognition of adakite-type gneisses in the North Dabie Mountain and its implication to ultrahigh pressure metamorphic geology. CHINESE SCIENCE BULLETIN-CHINESE 2000. [DOI: 10.1007/bf02909680] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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47
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Thiéblemont D, Stein G, Lescuyer JL. Gisements épithermaux et porphyriques: la connexion adakite. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s1251-8050(97)83970-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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49
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Kincaid C, Sacks IS. Thermal and dynamical evolution of the upper mantle in subduction zones. ACTA ACUST UNITED AC 1997. [DOI: 10.1029/96jb03553] [Citation(s) in RCA: 195] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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50
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