Late Mesozoic to Paleogene Stratigraphy of the Salar De Atacama Basin, Antofagasta, Northern Chile: Implications for the Tectonic Evolution of the Central Andes
Late Mesozoic to Paleogene stratigraphy of the Salar de Atacama Basin, Antofagasta, Northern Chile: Implications for the tectonic evolution of the Central Andes Constantino Mpodozisa,T,Ce´sar Arriagadab, Matilde Bassoc, Pierrick Roperchd, Peter Cobbolde, Martin Reichf aServicio Nacional de Geologı´a y Minerı´a, now at Sipetrol. SA, Santiago, Chile bDepartamento de Geologı´a, Universidad de Chile, Santiago, Chile cServicio Nacional de Geologı´a y Minerı´a, Santiago, Chile dIRD/Dep. de Geologı´a, Universidad de Chile, Santiago, Chile eGe´osciences-Rennes (UMR6118 du CNRS), France fDepartment of Geological Sciences University of Michigan, United States Abstract The Salar de Atacama basin, the largest bpre-AndeanQ basin in Northern Chile, was formed in the early Late Cretaceous as a consequence of the tectonic closure and inversion of the Jurassic–Early Cretaceous Tarapaca´ back arc basin. Inversion led to uplift of the Cordillera de Domeyko (CD), a thick-skinned basement range bounded by a system of reverse faults and blind thrusts with alternating vergence along strike. The almost 6000-m-thick, upper Cretaceous to lower Paleocene sequences (Purilactis Group) infilling the Salar de Atacama basin reflects rapid local subsidence to the east of the CD. Its oldest outcropping unit (Tonel Formation) comprises more than 1000 m of continental red sandstones and evaporites, which began to accumulate as syntectonic growth strata during the initial stages of CD uplift. Tonel strata are capped by almost 3000 m of sandstones and conglomerates of western provenance, representing the sedimentary response to renewed pulses of tectonic shortening, which were deposited in alluvial fan, fluvial and eolian settings together with minor lacustrine mudstone (Purilactis Formation).
[Show full text]