The statherian taphrogenesis of the South American Platform

Abstract

Records of Statherian intracontinental ruptural tectonics, magmatism and sedimentation events are recognized all over the South American Platform as an immediate tectonic response to the formation of a large continental domain during Rhyacian-Orosirian orogenic collage. In this paper, we present a preliminary synthesis of the variety of tectonic-sedimentary and magmatic occurrences of these taphrogenic processes along the Statherian Period, which are recorded in all cratons, as well as in the basement of most Brasiliano orogenic belts. The Statherian rock units are better preserved over the cratons, and within the Brasiliano structural provinces they are reduced by erosional processes and discretely overprinted by Tonian and Cryogenian structures, and strongly by the Ediacaran-Brasiliano Orogeny. Clastic sediments are dominantly mature, primary structures clearly pointing to the environmental setting. Anorogenic bimodal magmatism, represented by volcanic and plutonic rocks is common, where felsic rocks are largely dominant. Their geochemical signature indicates within-plate settings and dike swarms are common within the cratons. The magmatism was very intense locally, suggesting LIP occurrences, although in need of additional geophysical and petrological support. The taphrogenic and magmatic events took place within Orosirian and Rhyacian basement, in which main tectonic-magmatic events ceased just before the Late Statherian, occasionally extending into the Calymmian.

KEYWORDS:
Taphrogenesis; Statherian; mafic dikes; acid volcanism; granitic plutonism; intracontinental basins and belts