The CRP-1 core penetrated 148 m of Quaternary and lower Miocene glacigenic sediments. This material complements the Eocene trhough Miocene strata that was cored previously at CIROS-1, 70 km to the south. The paleoclimatic records of CRP-1 and CIROS-1 have been examined by calculating the Chemical Index of Alteration (CIA) of Nesbitt & Young (1982), using new data for CRP-1 materials and the data of Rose & Pyne (1988) for CIROS-1 mudstones. The CIA is calculated from the relative abundance of Al, K, Ca, and Na, and its magnitude increases as the effects of chemical weathering increase. However, changes in sediment provenance can also effect the CIA, and such changes appear to dominate some parts of the CRP-1 and CIROS-1 record.Relatively large (47-60) and variable CIA values in the lithologically defined „lower sequence“ at CIROS-1 record the influence of chemical weathering during the late Eocene, a result of relatively mild climates and glacial influence, but not glacial dominance. CIA values do decrease upsection through the Eocene, however, suggesting gradual climatic deterioration. The Oligocene and Miocene „upper sequence“ at CIROS-1 is characterized by lower (45-50) and more uniform CIA values. This part of the record clearly is affected by an increased contribution of mafic material derived from the McMurdo Volcanic Group, but also may indicate a change in paleoweathering intensity. CIA values for CRP-1 are uniformly low (<45) and decrease slightly upsection, suggesting glacial dominance, although an increased influx of McMurdo Volcanic Group material is also indicated.

for CIROS data (Tab. 2 from Roser & Pyne, 1989) see doi:10.1594/PANGAEA.54733

Supplement to: Krissek, Lawrence A; Kyle, Philip R (1998): Geochemical indicators of weathering and Cenozoic palaeoclimates in sediments from CRP-1 and CIROS-1, McMurdo Sound, Antarctica. Terra Antartica, 5(3), 673-680