PALYNOLOGY, PALYNOFACIES AND GEOCHEMISTRY ON THE TRIASSIC CASA PIEDRA FORMATION, RINCÓN BLANCO GROUP, ARGENTINE PRECORDILLERA: DEPOSITIONAL ENVIRONMENT AND HYDROCARBON POTENTIAL

OTTONE GUILLERMO; JAVIER MACINO; ERRA GEORGINA; FERNANDO LARRIESTRA; SILVIA BARREDO

AMEGHINIANA

ASOCIACION PALEONTOLOGICA ARGENTINA

Lugar: Buenos Aires; Año: 2019 vol. 56 p. 319 - 335

0002-7014

This paper presents the study of the kerogen recovered from the Casa de Piedra Formation. The analysis includes systematic palynology, palynofacies, organic geochemistry (total organic carbon ? TOC ? and pyrolysis Rock-Eval) and inorganic geochemistry (X-ray fluoroescence). A new spore species is introduced: Rugulatisporites claudiae sp. nov. Three palynofacies are defined throughout the unit. The uppermost horizons, P1, fluvial in origin, include low TOC contents, a kerogen Type III, mostly terrigenous-derived, and a relatively diverse miospore assemblage largely dominated by disaccate pollen grains of umkomasiaceous/ peltasperm affinity; the K/Rb ratio is high, V is scarce, and Mo is absent. The middle, lacustrine section, P2, includes relatively high TOC values, a mostly amorphous rich kerogen Type II, and abundant Botryococcus sp.; the K/Rb ratio is relatively low, V is high, and Mo is present. The kerogen at the basalmost horizon, P3, is similar to the uppermost section, but includes relatively high percentages of amorphous organic matter and Botryococcus sp.; the K/Rb ratio is the lowest of the section, V is relatively low, and Mo is absent. The kerogen from the lacustrine P2 exhibits a moderate hydrocarbon genetic potential (ca. 3 to 31 kg HC/ ton).