Unwrapping reworked crust at the Columbia supercontinent margin within central southern Amazon Craton using multi-source geophysics and geochronology data synergy
GEOSCIENCE FRONTIERS(2022)
Abstract
The geometry and evolution of pre-existing basement in accretionary belts bordering supercontinents are often unclear.Integrative interpretation of long-wavelength potential field satellite data can image deep crust structure,improving our understanding of lithospheric processes that formed these margins bottom-up.Here,we present a multidisciplinary interpretation of the lithospheric architecture of the central southern Amazon Craton,a fragment of an accretionary belt at the southwestern Columbia super-continent margin.Satellite-borne gravity and magnetic data,airborne magnetic data,passive seismic(Vp/Vs ratio,crustal thickness)and seismic tomography data reveals that basement terranes from the interior of the craton extend into the accretionary margin of Columbia.We demonstrate a vertically heterogeneous structure with an underlying strongly reworked pre-Columbia tectonic wedge that sus-tained prolonged modification during the supercontinent assembly as corroborated by Nd isotope and geochronology data.Nd isotope data suggest that the protracted orogenic wedge was influenced by sub-duction angle shifts over time,including addition of substantial juvenile material during slab retreat events.This interplay promoted Craton growth at the supercontinent margin while keeping a subtle record of the pre-existing framework.Our findings point to the possible misrepresentation of basement extension and geometry of supercontinent margins elsewhere.
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Key words
Satellite gravity,Satellite magnetics,Columbia,Accretionary belt,Amazon Craton,Geochronology
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