Inferring bottom circulation based on sediment pattern distribution in the San José Gulf, Patagonia Argentina

RODRIGO HERNADEZ-MORESINO; AUGUSTO CÉSAR CRESPI-ABRIL; GASPAR SORIA; ALBERTO SANCHEZ; FEDERICO ISLA; PEDRO BARON

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2018

0895-9811

The goal of this work was to infer the spatio-temporalpatterns of bottom circulation of San José Gulf (SJG), Patagonia, Argentina. The SJG is mainly affected by tidal circulation and presentstwo hydrographic domains. The Western Hydrographic Domain (WHD) presentsvertically mixed waters year-round contrary to the seasonal stratified Eastern HydrographicDomain (EHD), resulting in the formation of a thermal front between domains. Samples of sediments were collected in spring 2016 and summer 2017 at severallocations to analyze the grain-size composition by means of laser diffractometry.A conceptual model of bottom hydrodynamics was inferred based onsediment`s grain-size trends. Asymmetric dominant tidal currents affect bottomsediment distribution. A general northward sediment transport is dominant atthe WHD, while at the EHD there is a seasonal shift in the transport direction.There, a net northward transport with a counterclockwise gyre dominates bottomhydrodynamics at the end of the thermal front formation, conditioned byresidual currents. In contrast, a net southward circulation likely driven bystrong westerly winds throughout autumn and winter prevails at the beginning ofthe water column stratification. The inferred sediment transport suggests a netloss of material that has to be recovered by tidal currents entering throughthe mouth and coastal sources as runoff, landslides, and/or aeolian dust.