Dominant Lid Tectonics behaviour of continental lithosphere in Precambrian times:Palaeomagnetism confirms prolonged quasi-integrity and absence of supercontinent cycles  

作　　者：J.D.A.Piper 

机构地区：[1]Geomagnetism Laboratory,Department of Earth and Ocean Sciences, University of Liverpool

出　　处：《Geoscience Frontiers》2018年第1期61-89,共29页地学前缘（英文版）

摘　　要：Although Plate Tectonics cannot be effectively tested by palaeomagnetism in the Precambrian aeon due to the paucity of high precision poles spanning such a long time period,the possibility of Lid Tectonics is eminently testable because it seeks accordance of the wider dataset over prolonged intervals of time;deficiencies and complexities in the data merely contribute to dispersion.Accordance of palaeomagnetic poles across a quasi-integral continental crust for time periods of up to thousands of millions of years,together with recognition of very long intervals characterised by minimal polar motions(～2.6-2.0,～1.5-1.25 and～0.75-0.6 Ga)has been used to demonstrate that Lid Tectonics dominated this aeon.The new PALEOMAGIA database is used to refine a model for the Precambrian lid incorporating a large quasiintegral crescentric core running from South-Central Africa through Laurentia to Siberia with peripheral cratons subject to reorganisation at～2.1,～1.6 and～1.1 Ga.The model explains low levels of tidal friction,reduced heat balance,unique petrologic and isotopic signatures,and the prolonged crustal stability of Earth's"Middle Age",whilst density concentrations of the palaeomagnetic poles show that the centre of the continental lid was persistently focussed near Earth's rotation axis from～2.8 to 0.6 Ga.The exception was the～2.7-2.2 Ga interval defined by～90°polar movements which translated the periphery of the lid to the rotation pole for this quasi-static period,a time characterised by glaciation and low levels of magmatic activity;the～2.7 Ga shift correlates with key interval of mid-Archaean crustal growth to some 60-70%of the present volume and REE signatures whilst the～2.2 Ga shift correlates with the Lomagundiδ～(13)C and Great Oxygenation events.The palaeomagnetic signature of breakup of the lid at～0.6 Ga is recorded by the world-wide Ediacaran development of passive margins and associated environmental signatures of new ocean basins.This event defined the end of a dominant Lid TectonAlthough Plate Tectonics cannot be effectively tested by palaeomagnetism in the Precambrian aeon due to the paucity of high precision poles spanning such a long time period, the possibility of Lid Tectonics is eminently testable because it seeks accordance of the wider dataset over prolonged intervals of time;deficiencies and complexities in the data merely contribute to dispersion. Accordance of palaeomagnetic poles across a quasi-integral continental crust for time periods of up to thousands of millions of years,together with recognition of very long intervals characterised by minimal polar motions(～ 2.6-2.0.～1.5-1.25 and ～0.75—0.6 Ga) has been used to demonstrate that Lid Tectonics dominated this aeon. The new PALEOMAGIA database is used to refine a model for the Precambrian lid incorporating a large quasiintegral crescentric core running from South-Central Africa through Laurentia to Siberia with peripheral cratons subject to reorganisation at ～2.1,～1.6 and ～1.1 Ga. The model explains low levels of tidal friction, reduced heat balance, unique petrologic and isotopic signatures, and the prolonged crustal stability of Earth's "Middle Age",whilst density concentrations of the palaeomagnetic poles show that the centre of the continental lid was persistently focussed near Earth's rotation axis from ～2.8 to 0.6 Ga.The exception was the ～2.7-2.2 Ga interval defined by ～90° polar movements which translated the periphery of the lid to the rotation pole for this quasi-static period, a time characterised by glaciation and low levels of magmatic activity; the ～2.7 Ga shift correlates with key interval of mid-Archaean crustal growth to some 60-70% of the present volume and REE signatures whilst the ～2.2 Ga shift correlates with the Lomagundi δ～(13) C and Great Oxygenation events. The palaeomagnetic signature of breakup of the lid at ～0.6 Ga is recorded by the world-wide Ediacaran development of passive margins and associated environmental signatures of new ocean basins. This event defined the

关 键 词：LID TECTONICS Plate TECTONICS ARCHAEAN PROTEROZOIC PALAEOMAGNETISM PALEOMAGIA 

分 类 号：P[天文地球]