The Huncal Member of the Vaca Muerta Formation, Neuquén Basin of Argentina: Insight into biostratigraphy, structure, U-Pb detrital zircon ages and provenance

NAIPAUER, MAXIMILIANO; COMERIO M.; LESCANO, M; VENNARI, M; AGUIRRE-URRETA, MB; RAMOS, V

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2020

0895-9811

In the western sector of the Neuquén Basin, the organic-rich shales of theVaca Muerta Formation are intercalated with turbidite sandstone intervals and slumpstructures integrated in the Huncal Member. The age of the Huncal sandstones based onthe integration of the ammonite faunas, calcareous nannofossils and U-Pb analysis islate Berriasian in their type locality. The origin of this deposit is probably related withtwo lobes of turbiditic sandstones linked with a progradational regressive phase.Sandstones are lithic arkoses and feldspathic litharenites derived from recycled orogenicand dissected arc sources. The U-Pb ages confirm a mixed sedimentary provenancefrom the south and southeastern margins of the basin, specifically from Paleozoic andTriassic?Jurassic rocks of the North Patagonian Massif and the Huincul High. Thecomplex fold and fault system described in the sandstone levels was interpreted as theresult of slump processes with a main transport direction to the SW and W. Sandstonedeposits with slump structures assignable to the Huncal Member are present throughoutthe entire basin from the Tithonian to the Valanginian in the Vaca Muerta Formation.Therefore, the Huncal Member is a diachronic lithostratigraphic unit and its depositionprobably depended on different factors such as relative sea level changes, the position inthe ramp system or in the platform and slope configuration and internalmorphostructural features of the Neuquén Basin.