Sedimentay features in the Argentine Basin: A key to understand the evolution of oceanic current systems - Argentine Basin drifts I

Objectives

The Argentine Basin represent an important path within the global conveyor belt. Cold Antarctic Bottomwater AABW takes a northward path as a western boundary current through this basin, while North Atlantic Deep Water NADW takes a southern route as a western boundary current. Antarctic Intermediate Water AAIW also sets towards the north along the Argentine continental margin. The sedimentary sequences at the Argentine continental margin hence represent an important archive of the evolution of those water masses and their modifications e.g. due to plate tectonic events such as the opening of the Drake passage or the extensive emplacement of volcanic flows at the Rio Grande Rise.

The water masses formed sediment drifts, which document path and intensity of the flow. An identification and detailed analysis and mapping of the drift development in time will shed light on the evolution of the water masses. This in turn will lead to information on the climatic condition. Up to now mainly the drifts in the central Argentine Basin (e.g. Zapiola Drift) have been investigated. We will concentrate on the continental margin and study long-term interaction (Eocene-Holocene) of the currents with sediment input.

The main questions we want to address are the following:

• For which period can we identify the earliest traces of a modern type circulation?
• Can we identify a chronology of the regional paths and intensities of the different water masses?
• Can different phases of drift build-up be distinguished? If so, can they be linked to tectonic movements and/or climatic modifications?
• Can corresponding events be identified both in the Argentine Basin and the Cape Basin?

More than 10000 km of high quality seismic reflection data have been collected at the Argentine continental margin between 35 S and 50 S collected by the BGR are at our disposal. 

The project is carried out within the priority programme SAMPLE of the Deutsche Forschungsgemeinschaft.