Paleoarchean bedrock lithologies across the Makhonjwa Mountains of South Africa and Swaziland linked to geochemical,magnetic and tectonic data reveal early plate tectonic genes flanking subduction margins  

作　　者：Maarten de Wit Harald Furnes Scott MacLennan Moctar Doucouré Blair Schoene Ute Weckmann Uma Martinez Sam Bowring 

机构地区：[1]AEON-ESSRI (Africa Earth Observatory Network-Earth Stewardship Science Research Institute),Nelson Mandela University [2]Department of Earth Science & Centre for Geobiology,University of Bergen [3]Department of Geosciences,Princeton University [4]Department of Geosciences,Nelson Mandela University [5]Department Geophysics,GFZ-German Research Centre for Geosciences,Helmholtz Centre [6]GISCAPETOWN [7]Earth,Atmosphere and Planetary Sciences,Massachusetts Institute of Technology

出　　处：《Geoscience Frontiers》2018年第3期603-665,共63页地学前缘（英文版）

基　　金：funded from 1978 by the SACUGS (South African Committee for the International Union of Geological Sciences)on behalf of the CSIR (Council for scientific and Industrial Research);funding continued through the South African FRD(Foundation for Research and Development);the NRF(National Research Foundation);NRF funding was largely met through the joint SA-German Inkaba yeAfrica program;funded through the Global Change Program of DST(Department of Science and Technology);funded through the Norwegian Research Council;the Meltzer Fund(University of Bergen);funding from the Centre for Geobiology, University of Bergen;funded through Cor Langereis;Andrew Biggin (University Utrecht) by the Dutch ALWNWO (Aarden Levenswetenschappen division of the Nederlandse Organisatie voor Wetenschappelijk Onderzoek)

摘　　要：The Makhonjwa Mountains, traditionally referred to as the Barberton Greenstone Belt, retain an iconic Paleoarchean archive against which numerical models of early earth geodynamics can be tested. We present new geologic and structural maps, geochemical plots, geo- and thermo-chronology, and geophysical data from seven silicic, mafic to ultramafic complexes separated by major shear systems across the southern Makhonjwa Mountains. All reveal signs of modern oceanic back-arc crust and subductionrelated processes. We compare the rates of processes determined from this data and balance these against plate tectonic and plume related models. Robust rates of both horizontal and vertical tectonic processes derived from the Makhonjwa Mountain complexes are similar, well within an order of magnitude, to those encountered across modern oceanic and orogenic terrains flanking Western Pacific-like subduction zones. We conclude that plate tectonics and linked plate-boundary processes were well established by 3.2-3.6 Ga. Our work provides new constraints for modellers with rates of a 'basket' of processes against which to test Paleoarchean geodynamic models over a time period close to the length of the Phanerozoic.The Makhonjwa Mountains, traditionally referred to as the Barberton Greenstone Belt, retain an iconic Paleoarchean archive against which numerical models of early earth geodynamics can be tested. We present new geologic and structural maps, geochemical plots, geo- and thermo-chronology, and geophysical data from seven silicic, mafic to ultramafic complexes separated by major shear systems across the southern Makhonjwa Mountains. All reveal signs of modern oceanic back-arc crust and subductionrelated processes. We compare the rates of processes determined from this data and balance these against plate tectonic and plume related models. Robust rates of both horizontal and vertical tectonic processes derived from the Makhonjwa Mountain complexes are similar, well within an order of magnitude, to those encountered across modern oceanic and orogenic terrains flanking Western Pacific-like subduction zones. We conclude that plate tectonics and linked plate-boundary processes were well established by 3.2-3.6 Ga. Our work provides new constraints for modellers with rates of a 'basket' of processes against which to test Paleoarchean geodynamic models over a time period close to the length of the Phanerozoic.

关 键 词：Paleoarchean Barberton GREENSTONE Belt Onverwacht Suite Geologic BEDROCK and structural maps Geochemistry and geophysics PLATE tectonics 

分 类 号：P[天文地球]