POLYMICT FREQUENCIES IN LGM TILL AS A PROXY FOR PALEO ICESTREAM FLOW IN THE ROSS EMBAYMENT, ANTARCTICA
Three different types of polymicts were found and classified by plasmic fabric and internal structure. The classification of polymicts is as follows: (a) type 1 have diffuse edges and no internal structure, (b) type 2 have moderately defined edges, and a weak inner core grain and plasmic fabric and (c) type 3 have well-defined edges, an inner core grain and plasmic fabric.
Polymicts in core ELT32-21 in the Central Ross Sea contain 56% of type 2 polymicts and 21% of type 3 polymicts. Core NBP94-07-39 located in the East-Central Ross Sea contains 62% type 2 polymicts and 31% of type 1 polymicts. In the Eastern Ross Sea, core NBP99-02-17 contains 97% type 1 polymicts. Preliminary results show that polymict type beneath the Bindschadler Ice Stream is dominated by type 1 polymicts, similar to core NBP99-02-17, and the tills from Lonewolf Nunataks in East Antarctica have polymict types most similar to ELT32-21.
Between core variability of polymicts is thought to be related to clay type. X-ray diffraction will be used to determine the clay mineralogy of these samples to identify possible controls on polymict abundance and type.