Proveniencia de la Formación Springhill en las cuencas Austral y Malvinas a partir de edades U-Pb en circones detríticos

LOVECCHIO, JUAN PABLO; NAIPAUER MAXIMILIANO

MENDOZA

Congreso; 11º Congreso de Exploración y Desarrollo de Hidrocarburos; 2022

Instituto Argentino de Petrñoleo y Gas

continent, limit to the west with the Andean volcanic arc, to the east with the Malvinas (Falkland) islands,and are separated by the Rio Chico High, a southern extension of the Deseado Massif. These basinswere originated in the Mesozoic and are associated with a generalized rifting episode that affectedPatagonia in the Early-Middle Jurassic, characterized by profuse volcanism (Chon Aike MagmaticProvince, Tobífera Series). Since the Late Jurassic-Early Cretaceous, these basins went into a passivemargin phase, with the onset of deposition of the transgressive sandstones of the Springhill Formation(main reservoir unit across the study area).This study integrates U-Pb radiometric dating on detrital zircons of the Springhill Formation recoveredfrom six drilling cuttings samples from hydrocarbon exploration wells in the Austral basin and six coresamples from the Malvinas basin. The objective was to determine maximum deposition ages, andto characterize sediment provenance to better understand the participation of different sedimentprovenance areas and the contemporaneous volcanic arc.The external morphological analysis of the zircon grains highlighted differences between both basins.Idiomorphic and prismatic zircons (of volcanic origin) predominate in the Austral basin, while inMalvinas rounded and sub-rounded zircons are more common and were related to a larger degree ofreworking and a different source.Regarding provenance, the histogram pattern of U-Pb ages for the Springhill Formation in the Malvinasbasin shows dominance of Mesoproterozoic and Neoproterozoic-Cambrian sources related to theDeseado Massif and Rio Chico High. In the Austral-Magallanes basin Neoproterozoic-Cambrianzircons dominate while Mesoproterozoic zircons are absent; this was interpreted as produced bya more local source in Tierra del Fuego. Jurassic Chon Aike sources are present in both sets, asSpringhill Formation regionally overlies Tobifera Series (synrift volcanism). Despite the scarcity ofcontemporaneous Andean volcanic arc-related zircons in the Springhill Formation, it was possible todetermine Tithonian to Hauterivian maximum ages of deposition.