Abstract

The Argentine Margin is a passive volcanic continental margin formed as a result of the breakup of Gondwana and opening of the South Atlantic during the Early Cretaceous. How this occurred is still a matter of debate, with various models focusing on different aspects of the breakup and development of segmentation.

Seaward dipping reflectors (SDRs) underlie the Argentine continental margin; these are characteristic features of volcanic rifted margins, yet they have only been sampled through scientific ocean drilling in the NE Atlantic off Greenland and Norway in an area impacted by hotspot volcanism. Here we propose a drilling program to core two sites on the Argentine Margin to sample the SDRs and sedimentary record deposited since their formation. Sampling the SDRs to determine their age and composition will allow us to better understand the opening and fragmentation of the South Atlantic and in particular the source of the magma for initial melts emplaced during opening.

This will also help us to understand magma/crust interactions and the implications for crustal anatexis and the impact this volcanism had on climate through delivery of gases to the ocean/atmosphere. Following breakup, the progressive opening of the South Atlantic resulted in a major change in the configuration of landmasses and ocean water mass distribution, with significant implications for climate evolution during the Cretaceous. The Cretaceous Atlantic was marked by deposition of widespread black shales during oceanic anoxic events (OAEs), yet we do not fully understand what caused their formation. The record of Upper Cretaceous OAEs in the southern South Atlantic is sparse and sampling the Cretaceous on the Argentine margin could fill this gap and provide significant insight into the formation and expression of these deposits. During the Cenozoic, uplift of the Andes had a major impact on atmospheric circulation and landscape evolution in South America.

The Argentine Basin is an ideal location to recover records of this evolution and the impact it had on paleoclimate, including the development of the South American monsoon.

Finally, the non-steady state nature of sedimentation along the Argentine Margin due to continual reworking of sediments makes it an exciting setting to study the interactions of sedimentation, basin evolution, microbial life, and carbon fluxes.

Keywords: South Atlantic; Argentina Passive Volcanic Continental Margin; Andean Uplift; Oceanic Anoxic Events; Microbial Life