Inferencias paleoceanográficas en el sureste del Pacífico Subtropical deducidas a partir de un testigo de 380.000 años

Abstract

[EN] Study of TG-7 core from the Nazca Ridge allowed to reconstructed a 380.000 years record of the paleoceanographic evolution in the Southeastern Subtropical Pacific. The radiolarian microfossil assemblages, along with the textural characteristics, biogenic (calcium carbonate, opal, barium) and terrigenous (Al) sediment components, allowed the identification of three main periods. The first one was from IOS 11 to lower part of IOS 8 and is characterised by a Chile Current predominance. The second period, from upper part of IOS 8 to lower IOS 6, is defined by changing characteristics of terrigenous particles. The third period, from the upper IOS 6 to the Present, is identified by the prevalence of Modifying Subtropical Water. Data analysis suggest that from 380.000 years (IOS It) to 145.000 years (IOS 6), the centre of the anticyclonic gyre described by atmospheric and oceanic currents in the South Pacific was located northern than its present position, preventing the arrival of Equatorial waters to the study area. From stage 6 to stage I, the gyre centre has moved to its today location