CASADIO Silvio Alberto
Onset of foreland basin deposition in the Neuquén Basin (34°-35°S): New data from sedimentary petrology and U–Pb dating of detrital zircons from the Upper Cretaceous non-marine deposits
GÓMEZ, RICARDO; LOTHARI, LUCAS; TUNIK, MAISA; CASADIO, SILVIO
JOURNAL OF SOUTH AMERICAN EARTH SCIENCES
PERGAMON-ELSEVIER SCIENCE LTD
Año: 2019 vol. 95
A multi-proxy provenance approach using sedimentology, petrology and detrital zircon U?Pb geochronology provides new constrains for the evolution of theSouthern Central Andes. The Upper Cretaceous non-marine deposits of the Neuquén Basin referred as Neuquén Group in the central and southern sector of the basin,have been characterized as the first foreland basin associated with the early uplift of the Andean orogen at ca. 100 Ma. However, in the northern sector of the basin,the stratigraphically equivalent Diamante Formation has not been studied in detail yet. This work focuses in the outcrops of the Diamante Formation located betweenLaguna del Diamante and Atuel River in southern Mendoza Province, Argentina (34°-35°S). The petrographic analysis of sandstones shows high content of volcanicand calcareous lithic fragments suggesting provenance from the underlying sedimentary units and the coeval volcanic arc associated with the onset of an importantstage of deformation on the west. Detrital zircons from the base of the Diamante Formation were supplied sources from Upper Jurassic and Lower Cretaceous thatwere exposed during Upper Cretaceous times, whereas in the top, a high content of Permo-Triassic detrital zircons indicates exhumation of the surrounding Permo-Triassic crystalline basement. Finally, two maximum depositional ages were obtained, 107.2 ± 1.4 Ma to Vega de los Patos and 91.1 ± 2.2 Ma to Vega Grande,suggesting uninterrupted activity of the volcanic arc during foreland basin deposition. In particular, the age of 107.2 Ma would indicate that the sedimentation of theUpper Cretaceous non-marine deposits occurred in the Albian at these latitudes (34°-35°S), which suggests that the onset of the foreland basin sedimentation isdiachronic at different positions in the Neuquén Basin.