Sedimentology, Provenance and Radiometric Dating of the Silante Formation: Implications for the Cenozoic Evolution of the Western Andes of Ecuador

Minerals

Santiago Almagor¹  Vanessa Escobar¹  Cristian Vallejo¹  Wilfried Winkler²  Pieter Vermeesch³  JoseL. Herrera³  RichardA. Spikings⁴  Christian Romero⁵ 

[1] Departamento de Geología, Facultad de Ingeniería en Geología y Petróleos, Escuela Politécnica Nacional, Quito 170517, Ecuador;Department of Earth Sciences, ETH-Zürich, CH-8092 Zürich, Switzerland;Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK;Department of Earth Sciences, University of Geneva, CH-1205 Geneva, Switzerland;Instituto de Investigación Geológico Energético (IIGE), Quito 170518, Ecuador;

关键词: provenance analysis;    Western Andes;    Miocene;    Silante Formation;    Ecuador;   

DOI  :  10.3390/min10100929

来源: DOAJ

【 摘 要 】

The Silante Formation is a thick series of continental deposits, exposed along a trench-parallel distance of approximately 300 km within the Western Cordillera of Ecuador. The origin, tectonic setting, age and stratigraphic relationships are poorly known, although these are key to understand the Cenozoic evolution of the Ecuadorian Andes. We present new sedimentological, stratigraphic, petrographic, radiometric and provenance data from the Silante Formation and underlying rocks. The detailed stratigraphic analysis shows that the Silante Formation unconformably overlies Paleocene submarine fan deposits of the Pilalo Formation, which was coeval with submarine tholeiitic volcanism. The lithofacies of the Silante Formation suggest that the sediments were deposited in a debris flow dominated alluvial fan. Provenance analysis including heavy mineral assemblages and detrital zircon U-Pb ages indicate that sediments of the Silante Formation were derived from the erosion of a continental, calc-alkaline volcanic arc, pointing to the Oligocene to Miocene San Juan de Lachas volcanic arc. Thermochronological data and regional correlations suggest that deposition of the Silante Formation was coeval with regional rock and surface uplift of the Andean margin that deposited alluvial fans in intermontane and back-arc domains.

【 授权许可】

Unknown