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Tang M, Chen H, Lee CTA, Cao W. Subaerial crust emergence hindered by phase-driven lower crust densification on early Earth. SCIENCE ADVANCES 2024; 10:eadq1952. [PMID: 39259787 DOI: 10.1126/sciadv.adq1952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Accepted: 08/06/2024] [Indexed: 09/13/2024]
Abstract
Earth owes much of its dynamic surface to its bimodal hypsometry, manifested by high-riding continents and low-riding ocean basins. The thickness of the crust in the lithosphere exerts the dominant control on the long-wavelength elevations of continents. However, there is a limit to how high elevations can rise by crustal thickening. With continuous crustal thickening, the mafic lower crust eventually undergoes a densifying phase transition, arresting further elevation gain-an effect clearly observed in modern orogenic belts. On early Earth, lower crust densification should also limit how high a thickening crust can rise, regardless of the thickening mechanisms. We suggest that lower crust densification combined with a thicker oceanic crust in the Archean may have limited the whole-Earth topographic relief to 3 to 5 kilometers at most-half that of the present day. Unless the oceans were far less voluminous, limited relief would inevitably lead to a water world on early Earth.
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Affiliation(s)
- Ming Tang
- Key Laboratory of Orogenic Belt and Crustal Evolution, MOE, School of Earth and Space Sciences, Peking University, Beijing 100871, China
| | - Hao Chen
- Key Laboratory of Orogenic Belt and Crustal Evolution, MOE, School of Earth and Space Sciences, Peking University, Beijing 100871, China
| | - Cin-Ty A Lee
- Department of Earth, Environmental and Planetary Sciences, Rice University, Houston, TX 77005, USA
| | - Wenrong Cao
- Department of Geological Sciences and Engineering, University of Nevada, Reno, MS-172, 1664 N. Virginia St., Reno, NV 89557, USA
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Widiyantoro S, Supendi P, Ardianto A, Baskara AW, Bacon CA, Damanik R, Rawlinson N, Gunawan E, Sahara DP, Zulfakriza Z, Husni YM, Lesmana A. Implications for fault locking south of Jakarta from an investigation of seismic activity along the Baribis fault, northwestern Java, Indonesia. Sci Rep 2022; 12:10143. [PMID: 35710692 PMCID: PMC9203524 DOI: 10.1038/s41598-022-13896-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Accepted: 05/30/2022] [Indexed: 12/04/2022] Open
Abstract
Recent borehole seismic deployments conducted along the Baribis Fault in northwestern Java reveal that it may be active. In this study, we exploit these data to locate proximal earthquakes using a relative relocation technique, estimate their moment magnitudes using a spectral fitting method and compute their focal mechanisms via waveform inversion. We observe that seismicity in the eastern part of the fault is significantly higher than in the west, where a previous GPS study of the region south of Jakarta demonstrated the existence of high compression rates. These observations imply that the western Baribis Fault is locked, and that neighbouring areas, including southern Jakarta and its surroundings, may be highly vulnerable to future sizeable earthquakes when accumulated elastic strain energy is eventually released during fault rupture. Significantly, the current generation of Indonesia's national hazard maps have not considered seismicity along the Baribis Fault. Our new results therefore call for an urgent reappraisal of the seismic hazard in northwestern Java that carefully takes into account the Baribis Fault and its earthquake potential, particularly in light of its proximity to Jakarta, a megacity that lies at the heart of one of the most densely populated islands in the world.
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Affiliation(s)
- S Widiyantoro
- Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, 40132, Indonesia
- Faculty of Engineering, Maranatha Christian University, Bandung, 40164, Indonesia
| | - P Supendi
- Agency for Meteorology, Climatology, and Geophysics (BMKG), Jakarta, 10720, Indonesia
- Department of Earth Sciences, Bullard Labs, University of Cambridge, Cambridge, CB3 0EZ, UK
| | - A Ardianto
- Geophysical Engineering Study Program, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, 40132, Indonesia
| | - A W Baskara
- Geophysical Engineering Study Program, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, 40132, Indonesia
| | - C A Bacon
- Department of Earth Sciences, Bullard Labs, University of Cambridge, Cambridge, CB3 0EZ, UK
| | - R Damanik
- Geophysical Engineering Study Program, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, 40132, Indonesia
- PT. Reasuransi Maipark, Multivision Tower, Menteng Atas, Jakarta, 12960, Indonesia
| | - N Rawlinson
- Department of Earth Sciences, Bullard Labs, University of Cambridge, Cambridge, CB3 0EZ, UK.
| | - E Gunawan
- Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, 40132, Indonesia
| | - D P Sahara
- Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, 40132, Indonesia
| | - Z Zulfakriza
- Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, 40132, Indonesia
| | - Y M Husni
- Geophysical Engineering Study Program, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, 40132, Indonesia
| | - A Lesmana
- Geophysical Engineering Study Program, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, 40132, Indonesia
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Widiyantoro S, Ramdhan M, Métaxian JP, Cummins PR, Martel C, Erdmann S, Nugraha AD, Budi-Santoso A, Laurin A, Fahmi AA. Seismic imaging and petrology explain highly explosive eruptions of Merapi Volcano, Indonesia. Sci Rep 2018; 8:13656. [PMID: 30209278 PMCID: PMC6135845 DOI: 10.1038/s41598-018-31293-w] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 08/16/2018] [Indexed: 11/08/2022] Open
Abstract
Our seismic tomographic images characterize, for the first time, spatial and volumetric details of the subvertical magma plumbing system of Merapi Volcano. We present P- and S-wave arrival time data, which were collected in a dense seismic network, known as DOMERAPI, installed around the volcano for 18 months. The P- and S-wave arrival time data with similar path coverage reveal a high Vp/Vs structure extending from a depth of ≥20 km below mean sea level (MSL) up to the summit of the volcano. Combined with results of petrological studies, our seismic tomography data allow us to propose: (1) the existence of a shallow zone of intense fluid percolation, directly below the summit of the volcano; (2) a main, pre-eruptive magma reservoir at ≥ 10 to 20 km below MSL that is orders of magnitude larger than erupted magma volumes; (3) a deep magma reservoir at MOHO depth which supplies the main reservoir; and (4) an extensive, subvertical fluid-magma-transfer zone from the mantle to the surface. Such high-resolution spatial constraints on the volcano plumbing system as shown are an important advance in our ability to forecast and to mitigate the hazard potential of Merapi's future eruptions.
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Affiliation(s)
- S Widiyantoro
- Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Bandung Institute of Technology, Bandung, 40132, Indonesia.
- Research Center for Disaster Mitigation, Bandung Institute of Technology, Bandung, 40132, Indonesia.
| | - M Ramdhan
- Study Program of Earth Sciences, Faculty of Earth Sciences and Technology, Bandung Institute of Technology, Bandung, 40132, Indonesia
- Agency for Meteorology, Climatology and Geophysics, Jakarta, 10720, Indonesia
| | - J-P Métaxian
- ISTerre, IRD R219, CNRS, Université de Savoie Mont Blanc, Le Bourget-du-Lac, France
- Institut de Physique du Globe de Paris, Université Sorbonne-Paris-Cité, CNRS, Paris, France
| | - P R Cummins
- Research School of Earth Sciences, Australian National University, Canberra, ACT, 2601, Australia
| | - C Martel
- Institut des Sciences de la Terre d'Orléans (ISTO), Université d'Orléans-CNRS-BRGM, Orléans, France
| | - S Erdmann
- Institut des Sciences de la Terre d'Orléans (ISTO), Université d'Orléans-CNRS-BRGM, Orléans, France
| | - A D Nugraha
- Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Bandung Institute of Technology, Bandung, 40132, Indonesia
| | - A Budi-Santoso
- Center for Volcanology and Geological Hazard Mitigation, Geological Agency, Bandung, 40122, Indonesia
| | - A Laurin
- ISTerre, IRD R219, CNRS, Université de Savoie Mont Blanc, Le Bourget-du-Lac, France
| | - A A Fahmi
- ISTerre, IRD R219, CNRS, Université de Savoie Mont Blanc, Le Bourget-du-Lac, France
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Advokaat EL, Marshall NT, Li S, Spakman W, Krijgsman W, van Hinsbergen DJJ. Cenozoic Rotation History of Borneo and Sundaland, SE Asia Revealed by Paleomagnetism, Seismic Tomography, and Kinematic Reconstruction. TECTONICS 2018; 37:2486-2512. [PMID: 30333679 PMCID: PMC6175333 DOI: 10.1029/2018tc005010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 06/27/2018] [Accepted: 06/29/2018] [Indexed: 06/08/2023]
Abstract
SE Asia comprises a heterogeneous assemblage of fragments derived from Cathaysia (Eurasia) in the north and Gondwana in the south, separated by suture zones representing closed former ocean basins. The western part of the region comprises Sundaland, which was formed by Late Permian-Triassic amalgamation of continental and arc fragments now found in Indochina, the Thai Penisula, Peninsular Malaysia, and Sumatra. On Borneo, the Kuching Zone formed the eastern margin of Sundaland since the Triassic. To the SE of the Kuching Zone, the Gondwana-derived continental fragments of SW Borneo and East Kalimantan accreted in the Cretaceous. South China-derived fragments accreted to north of the Kuching Zone in the Miocene. Deciphering this complex geodynamic history of SE Asia requires restoration of its deformation history, but quantitative constraints are often sparse. Paleomagnetism may provide such constraints. Previous paleomagnetic studies demonstrated that Sundaland and fragments in Borneo underwent vertical axis rotations since the Cretaceous. We provide new paleomagnetic data from Eocene-Miocene sedimentary rocks in the Kutai Basin, east Borneo, and critically reevaluate the published database, omitting sites that do not pass widely used, up-to-date reliability criteria. We use the resulting database to develop an updated kinematic restoration. We test the regional or local nature of paleomagnetic rotations against fits between the restored orientation of the Sunda Trench and seismic tomography images of the associated slabs. Paleomagnetic data and mantle tomography of the Sunda slab indicate that Sundaland did not experience significant vertical axis rotations since the Late Jurassic. Paleomagnetic data show that Borneo underwent a ~35° counterclockwise rotation constrained to the Late Eocene and an additional ~10° counterclockwise rotation since the Early Miocene. How this rotation was accommodated relative to Sundaland is enigmatic but likely involved distributed extension in the West Java Sea between Borneo and Sumatra. This Late Eocene-Early Oligocene rotation is contemporaneous with and may have been driven by a marked change in motion of Australia relative to Eurasia, from eastward to northward, which also has led to the initiation of subduction along the eastern Sunda trench and the proto-South China Sea to the south and north of Borneo, respectively.
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Affiliation(s)
| | | | - Shihu Li
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and GeophysicsChinese Academy of SciencesBeijingChina
| | - Wim Spakman
- Department of Earth SciencesUtrecht UniversityUtrechtNetherlands
- Centre of Earth Evolution and DynamicsUniversity of OsloOsloNorway
| | - Wout Krijgsman
- Department of Earth SciencesUtrecht UniversityUtrechtNetherlands
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5
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Geochemistry and Structure of Krakatoa Volcano in the Sunda Strait, Indonesia. GEOSCIENCES 2018. [DOI: 10.3390/geosciences8040111] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
A simple model for necking and detachment of subducting slabs is developed to include the coupling between grain-sensitive rheology and grain-size evolution with damage. Necking is triggered by thickened buoyant crust entrained into a subduction zone, in which case grain damage accelerates necking and allows for relatively rapid slab detachment, i.e., within 1 My, depending on the size of the crustal plug. Thick continental crustal plugs can cause rapid necking while smaller plugs characteristic of ocean plateaux cause slower necking; oceanic lithosphere with normal or slightly thickened crust subducts without necking. The model potentially explains how large plateaux or continental crust drawn into subduction zones can cause slab loss and rapid changes in plate motion and/or induce abrupt continental rebound.
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Ismail-Zadeh A, Honda S, Tsepelev I. Linking mantle upwelling with the lithosphere descent [corrected] and the Japan Sea evolution: a hypothesis. Sci Rep 2013; 3:1137. [PMID: 23355951 PMCID: PMC3555085 DOI: 10.1038/srep01137] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 12/27/2012] [Indexed: 11/09/2022] Open
Abstract
Recent seismic tomography studies image a low velocity zone (interpreted as a high temperature anomaly) in the mantle beneath the subducting Pacific plate near the Japanese islands at the depth of about 400 km. This thermal feature is rather peculiar in terms of the conventional view of mantle convection and subduction zones. Here we present a dynamic restoration of the thermal state of the mantle beneath this region assimilating geophysical, geodetic, and geological data up to 40 million years. We hypothesise that the hot mantle upwelling beneath the Pacific plate partly penetrated through the subducting plate into the mantle wedge and generated two smaller hot upwellings, which contributed to the rapid subsidence in the basins of the Japan Sea and to back-arc spreading. Another part of the hot mantle migrated upward beneath the Pacific lithosphere, and the presently observed hot anomaly is a remnant part of this mantle upwelling.
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Affiliation(s)
- Alik Ismail-Zadeh
- Institut für Angewandte Geowissenschaften, Karlsruher Institut für Technologie, Karlsruhe, Germany.
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Li C, van der Hilst RD. Structure of the upper mantle and transition zone beneath Southeast Asia from traveltime tomography. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009jb006882] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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9
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Piromallo C, Morelli A. Pwave tomography of the mantle under the Alpine-Mediterranean area. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002jb001757] [Citation(s) in RCA: 522] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
| | - Andrea Morelli
- Istituto Nazionale di Geofisica e Vulcanologia; Rome Italy
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10
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Foley SF, Buhre S, Jacob DE. Evolution of the Archaean crust by delamination and shallow subduction. Nature 2003; 421:249-52. [PMID: 12529633 DOI: 10.1038/nature01319] [Citation(s) in RCA: 167] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The Archaean oceanic crust was probably thicker than present-day oceanic crust owing to higher heat flow and thus higher degrees of melting at mid-ocean ridges. These conditions would also have led to a different bulk composition of oceanic crust in the early Archaean, that would probably have consisted of magnesium-rich picrite (with variably differentiated portions made up of basalt, gabbro, ultramafic cumulates and picrite). It is unclear whether these differences would have influenced crustal subduction and recycling processes, as experiments that have investigated the metamorphic reactions that take place during subduction have to date considered only modern mid-ocean-ridge basalts. Here we present data from high-pressure experiments that show that metamorphism of ultramafic cumulates and picrites produces pyroxenites, which we infer would have delaminated and melted to produce basaltic rocks, rather than continental crust as has previously been thought. Instead, the formation of continental crust requires subduction and melting of garnet-amphibolite--formed only in the upper regions of oceanic crust--which is thought to have first occurred on a large scale during subduction in the late Archaean. We deduce from this that shallow subduction and recycling of oceanic crust took place in the early Archaean, and that this would have resulted in strong depletion of only a thin layer of the uppermost mantle. The misfit between geochemical depletion models and geophysical models for mantle convection (which include deep subduction) might therefore be explained by continuous deepening of this depleted layer through geological time.
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Affiliation(s)
- Stephen F Foley
- Institut für Geologische Wissenschaften, Universität Greifswald, Germany.
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11
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Grand SP. Mantle shear-wave tomography and the fate of subducted slabs. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2002; 360:2475-2491. [PMID: 12460476 DOI: 10.1098/rsta.2002.1077] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A new seismic model of the three-dimensional variation in shear velocity throughout the Earth's mantle is presented. The model is derived entirely from shear bodywave travel times. Multibounce shear waves, core-reflected waves and SKS and SKKS waves that travel through the core are used in the analysis. A unique aspect of the dataset used in this study is the use of bodywaves that turn at shallow depths in the mantle, some of which are triplicated. The new model is compared with other global shear models. Although competing models show significant variations, several large-scale structures are common to most of the models. The high-velocity anomalies are mostly associated with subduction zones. In some regions the anomalies only extend into the shallow lower mantle, whereas in other regions tabular high-velocity structures seem to extend to the deepest mantle. The base of the mantle shows long-wavelength high-velocity zones also associated with subduction zones. The heterogeneity seen in global tomography models is difficult to interpret in terms of mantle flow due to variations in structure from one subduction zone to another. The simplest interpretation of the seismic images is that slabs in general penetrate to the deepest mantle, although the flow is likely to be sporadic. The interruption in slab sinking is likely to be associated with the 660 km discontinuity.
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Affiliation(s)
- Steven P Grand
- Department of Geological Sciences, University of Texas at Austin, 78712-1101, USA
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12
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Kopp H. Crustal structure of the Java margin from seismic wide-angle and multichannel reflection data. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/2000jb000095] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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13
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Mueller H, Massonne HJ. Experimental high pressure investigation of partial melting in natural rocks and their influence on Vp and Vs. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s1464-1895(01)00062-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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14
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Ye K, Cong B, Ye D. The possible subduction of continental material to depths greater than 200 km. Nature 2000; 407:734-6. [PMID: 11048717 DOI: 10.1038/35037566] [Citation(s) in RCA: 429] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Determining the depth to which continental lithosphere can be subducted into the mantle at convergent plate boundaries is of importance for understanding the long-term growth of supercontinents as well as the dynamic processes that shape such margins. Recent discoveries of coesite and diamond in regional ultrahigh-pressure (UHP) metamorphic rocks has demonstrated that continental material can be subducted to depths of at least 120 km (ref. 1), and subduction to depths of 150-300 km has been inferred from garnet peridotites in orogenic UHP belts based on several indirect observations. But continental subduction to such depths is difficult to trace directly in natural UHP metamorphic crustal rocks by conventional mineralogical and petrological methods because of extensive late-stage recrystallization and the lack of a suitable pressure indicator. It has been predicted from experimental work, however, that solid-state dissolution of pyroxene should occur in garnet at depths greater than 150 km (refs 6-8). Here we report the observation of high concentrations of clinopyroxene, rutile and apatite exsolutions in garnet within eclogites from Yangkou in the Sulu UHP metamorphic belt, China. We interpret these data as resulting from the high-pressure formation of pyroxene solid solutions in subducted continental material. Appropriate conditions for the Na2O concentrations and octahedral silicon observed in these samples are met at depths greater than 200 km.
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Affiliation(s)
- K Ye
- Laboratory of Lithosphere Tectonic Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing.
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Kárason H, van der Hilst RD. Constraints on Mantle Convection From Seismic Tomography. GEOPHYSICAL MONOGRAPH SERIES 2000. [DOI: 10.1029/gm121p0277] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Zhong D, Ji J, Hu S. Subduction age of Neo-Tethys oceanic crust in southwest Yunnan, China: Laser micro-area40Ar-39Ar dating. CHINESE SCIENCE BULLETIN-CHINESE 1999. [DOI: 10.1007/bf03182708] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Schöffel HJ, Das S. Fine details of the Wadati-Benioff zone under Indonesia and its geodynamic implications. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1999jb900091] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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19
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Bijwaard H, Spakman W, Engdahl ER. Closing the gap between regional and global travel time tomography. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/98jb02467] [Citation(s) in RCA: 824] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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20
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Kennett BLN, Widiyantoro S, van der Hilst RD. Joint seismic tomography for bulk sound and shear wave speed in the Earth's mantle. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/98jb00150] [Citation(s) in RCA: 202] [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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22
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Flanagan MP, Shearer PM. Global mapping of topography on transition zone velocity discontinuities by stackingSSprecursors. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/97jb03212] [Citation(s) in RCA: 369] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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23
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SUNARDI E, KIMURA JI. Temporal chemical variations in late Cenozoic volcanic rocks around The Bandung Basin, West Java, Indonesia. ACTA ACUST UNITED AC 1998. [DOI: 10.2465/ganko.93.103] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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24
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Upper mantle structure beneath Australia from portable array deployments. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/gd026p0039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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25
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Deep subduction and aspherical variations in P-wavespeed at the base of Earth's mantle. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/gd028p0005] [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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26
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Ernst WG, Maruyama S, Wallis S. Buoyancy-driven, rapid exhumation of ultrahigh-pressure metamorphosed continental crust. Proc Natl Acad Sci U S A 1997; 94:9532-7. [PMID: 11038569 PMCID: PMC23212 DOI: 10.1073/pnas.94.18.9532] [Citation(s) in RCA: 195] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Preservation of ultrahigh-pressure (UHP) minerals formed at depths of 90-125 km require unusual conditions. Our subduction model involves underflow of a salient (250 +/- 150 km wide, 90-125 km long) of continental crust embedded in cold, largely oceanic crust-capped lithosphere; loss of leading portions of the high-density oceanic lithosphere by slab break-off, as increasing volumes of microcontinental material enter the subduction zone; buoyancy-driven return toward midcrustal levels of a thin (2-15 km thick), low-density slice; finally, uplift, backfolding, normal faulting, and exposure of the UHP terrane. Sustained over approximately 20 million years, rapid ( approximately 5 mm/year) exhumation of the thin-aspect ratio UHP sialic sheet caught between cooler hanging-wall plate and refrigerating, downgoing lithosphere allows withdrawal of heat along both its upper and lower surfaces. The intracratonal position of most UHP complexes reflects consumption of an intervening ocean basin and introduction of a sialic promontory into the subduction zone. UHP metamorphic terranes consist chiefly of transformed, yet relatively low-density continental crust compared with displaced mantle material-otherwise such complexes could not return to shallow depths. Relatively rare metabasaltic, metagabbroic, and metacherty lithologies retain traces of phases characteristic of UHP conditions because they are massive, virtually impervious to fluids, and nearly anhydrous. In contrast, H2O-rich quartzofeldspathic, gneissose/schistose, more permeable metasedimentary and metagranitic units have backreacted thoroughly, so coesite and other UHP silicates are exceedingly rare. Because of the initial presence of biogenic carbon, and its especially sluggish transformation rate, UHP paragneisses contain the most abundantly preserved crustal diamonds.
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Affiliation(s)
- W G Ernst
- Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305-2115, USA
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27
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van der Hilst RD, Widiyantoro S, Engdahl ER. Evidence for deep mantle circulation from global tomography. Nature 1997. [DOI: 10.1038/386578a0] [Citation(s) in RCA: 1021] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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