The Cuicateco Terrane: Z a Oceanic Basin with Subduction Influence in the Upper Cretaceous in the Southern Mexico? New Structural, Geochemical and Geochronological Data
Chemical composition of the amphibolitic rocks of the Cuicateco terrane is toleitic basalts MORB (SiO2 45-50%), with a depletion in light rare earths and flat high rare earths patterns. Trace elements show a pattern depleted in incompatible elements, a slight enrichment in compatible elements, and negative anomalies of Nb and Th. A contribution of subduction-related magmas is also shown.
U-Pb dating by LA-MC-ICPMS on zircons belonging to the amphibolite, which yielded a maastrichtian age (65.6 ± 0.2 Ma) interpreted as the crystallization age of the basaltic protolith. Detrital U-Pb analyses on zircons of a vulcanoclastic phyllite suggest a maximum depositional maastrichtian age (~ 78 Ma). Zircons belonging to a sandstone of the Todos Santos Formation indicate a maximum depositional age, later to Middle-Upper Triassic (228 Ma).
The data obtained suggest the development of a basic volcanism in an ocean basin environment with a subduction-related influence during the Late Cretaceous,. that suffered the effect of two events, a transpressive and other compressive, during the latest Cretaceous - Paleocene, following by normal-lateral faulting miocenic.