T267 Plate Tectonics, Arc-Trench Systems, Cordilleran Tectonics, Sedimentary Basins, Sandstone Provenance, and Geoarchaeology (Posters): A Celebration of William R. Dickinson's Career

Tuesday, 27 September 2016
9:00 AM - 6:30 PM
Exhibit Hall E/F

CAMBRIAN STRIKE-SLIP EMPLACEMENT OF PAMPIA AND AREQUIPA ON CORDILLERAN MARGIN OF AMAZONIA: EVIDENCE FROM GEOCHRONOLOGY OF THE UMACHIRI FORMATION, PERU

Paper number: T267-26
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

Cambrian magmatism and deformation in the Cental Andes of SW South America have typically been attributed to the late stages of the Pampean orogeny (~540 Ma) or the early stages of the Famatanian orogeny (~470 Ma). Yet, critical to tectonic models of the Cordilleran margin of South America is an improved recognition of mid-Cambrian events associated with the emplacement and translation of exotic terranes. Here we present a new LA-ICPMS and CA-ID-TIMS geochronological constraints on the Umachiri Formation, which we suggest was deposited in a narrow strike-slip basin. Zircon from volcaniclaastic horizons within fine-grained siliciclastic strata yield ages as young as ~790 Ma that we correlate with the Gannakouriep dike swarm on the Kalahari carton. These data inspire a new tectonic model in which the Arequipa and Pampean terranes originated from the Kalahari carton, were dextrally translated in the mid-Cambrian, and were emplaned onto the Amazonian margin in the latest Cambrian.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-282714

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