THE WEDDELL SEA IN THE PLIOCENE: INTERPRETING THE SEDIMENT RECORD FROM ODP SITES 693 AND 697
In contrast, Site 693, 2480 mbsl, is adjacent to Dronning Maud Land on a shelf bench. Its terrigeneous sediments are sourced exclusively by the East Antarctic Ice Sheet (EAIS). Core 8R, the focus of this study, was deposited during Chron 2Ar (3.58-4.18 my). Most of the closely-spaced samples (roughly 1 sample/2-3 kyr) show little variation in wt% biosilica and wt% IRD. The exception is around 4 Ma where biosilica ranges between 6 and 14%, while IRD is relatively constant at 2 wt%. These changes do not parallel the LR04 stack, suggesting limited interaction at this site with the global ocean. Nevertheless, the limited age range 400-650 Ma (Pan African orogeny) and heavy mineral assemblages dominated by clinopyroxenes and calcium-rich amphiboles, suggest a single source and support the interpretation that this portion of the EAIS was relatively stable at this time. At both sites the highest biosilica content is where the wt% IRD is the lowest, suggesting no or limited ice and high productivity.