Palynomorphs from the Devonian Talacasto and Punta Negra Formations, Argentinean Precordillera: New biostratigraphic approach. (October 2018) - García Muro, Victoria J.
Abstract: Marine and terrestrial palynomorphs from the Loma de los Piojos section of the Precordillera Basin, western Argentina, were analyzed. The studied section embraces the upper part of the Lower Devonian Talacasto Formation and the whole Lower-Middle? Devonian Punta Negra Formation, which constitute the Gualilán Group. Terrestrial palynomorphs dominate the Talacasto Formation whereas marine palynomorphs dominate the Punta Negra Formation. Even though palynomorphs are scarce, poorly preserved, and marked by low diversity, they enable, together with previous palynological data, a new biostratigraphic interpretation for the Devonian units of the Gualilán Group. In addition, an age reassessment of the guide horizon of Keidel (1921), and a correlation of sections from different parts of the basin are provided. Based on palynological data, the age of the Talacasto Formation is constrained to the Lochkovian-late Pragian and the age of the Punta Negra Formation is now considered to be restricted to the late Pragian-Emsian, although a younger age for the uppermost part of Punta Negra is possible. Highlights: Devonian palynological assemblages from the Argentinean Precordillera are presented. Marine and terrestrial palynomorphs suggest a late Pragian to Emsian age. The age of the guide horizon of Keidel is constrained to the late Pragian. Palynological data enable a new biostratigraphic frame for the Devonian units.