FIRST POSSIBLE RECORD OF THE HIRNANTIAN GLACIATION IN THE CAPARO REGION, VENEZUELAN ANDES

JESSICA GOMEZ; JAIME REYES-ABRIL; JUAN CARLOS GUTIÉRREZ-MARCO; JEAN-FRANÇOIS BUONCRISTIANI

Villeneuve d'Ascq

Congreso; 2021 Virtual Annual Meeting of IGCP 653/ 2021 Virtual Annual Meeting of IGCP 735; 2021

Studies of the Ordovician rocks of the southern Andean flank have focused on the lithostratigraphic and biostratigraphic description of the Caparo Formation, the first descriptions of this unit assign it an Ordovician age, later that, three faunal levels were recognized whose age did not reach the Late Ordovician. In oil exploration projects, stratigraphic successions on eight localities of the Caparo region were reviewed, obtaining a composition of siltstones and sandstones intercalated with conglomerates for the Caparo Formation, and presence of Late Ordovician trilobites, brachiopods, corals, crinoids, bivalves, bryozoans and sponges, dated as Sandbian by the graptolite fauna of Nemagraptus gracilis Zone recorded with the assemblage. Overlying the Caparo Formation, a thick Silurian succession (early Llandovery to Wenlock) was defined, having yielded prolific brachiopod assemblages dominated by genera such as Meifodia, Eostropheodonta, Eocoelia and Antirhynchonella. The stratigraphic contact between the Ordovician and Silurian strata was proposed to be a hiatus involving the apparent absence of Katian to Hirnantian sedimentary record. However, the detailed study of three localities along of Uribante-Caparo dam reservoir (Paso Caparo, Caparito and El Cambur creek sections) has allowed to record a relatively thin (