INVESTIGADORES
SPALLETTI Luis Antonio
artículos
Título:
Petrographic, mineralogical and geochemical characterization of fine-grained rocks of the Pilmatué Member (Upper Valanginian ? Lower Hauterivian) of the Neuquén Basin (Argentina): implications for siliciclastic input, carbonate productivity and redox cond
Autor/es:
REMÍREZ, M.; SPALLETTI, L. E ISLA, M.
Revista:
JOURNAL OF SOUTH AMERICAN EARTH SCIENCES
Editorial:
PERGAMON-ELSEVIER SCIENCE LTD
Referencias:
Lugar: Amsterdam; Año: 2020 vol. 102
ISSN:
0895-9811
Resumen:
Petrographic, mineralogical and geochemical analyses of mixed siliciclastic-carbonate offshore deposits of the Pilmatué Member (Neuquén Basin) were carried out to define two scenarios for deposition: a confined ramp setting (CRS) and an open ramp setting (ORS). The CRS involves marly to carbonate-rich fine-grained mudstones, mostly laminated and non-bioturbated, enriched in redox proxies and depleted in rare earth elements (REE). The ORS comprises abundant siliciclastic-rich mudstones, mostly coarser-mudstones, depleted in redox proxies and with REE pattern similar to the PAAS. These variations are explained through fluctuations in carbonate productivity/terrigenous input, and changes in the circulation pattern of the basin. Within the CRS, high carbonate productivity would be favored due to the general greenhouse condition for the Early Cretaceous andthe scarcity of terrigenous supply, related to the landward migration of the shoreline and low effectiveness of sediment distribution by marine currents. Furthermore, high organic matter productivity should lead to an oxygen-depletion close to the sediment-water interface. Instead, increasing sediment supply and dissolved oxygen in the ORS is related to shoreline progradation in the south and the consequent installation of across shelf flows that allowed vertical water circulation and the oxygen replenishment in benthic environment.