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 geolog...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.展开更多
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)+7 种基金the NRF(National Research Foundation)NRF funding was largely met through the joint SA-German Inkaba yeAfrica programfunded through the Global Change Program of DST(Department of Science and Technology)funded through the Norwegian Research Councilthe Meltzer Fund(University of Bergen)funding from the Centre for Geobiology, University of Bergenfunded through Cor LangereisAndrew Biggin (University Utrecht) by the Dutch ALWNWO (Aarden Levenswetenschappen division of the Nederlandse Organisatie voor Wetenschappelijk Onderzoek)
文摘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.
