MID-PALEOCENE DROPSTONES IN THE WHANGAI FORMATION, NEW-ZEALAND - EVIDENCE OF MID-PALEOCENE COLD CLIMATE

Sedimentological, micropalaeontological and organic geochemical (Rock- Eval pyrolysis) criteria suggest that calving glaciers, probably from Antarctica, likely reached the sea and floated by New Zealand during t he middle Paleocene, dropping angular coarse detritus into marine mud. The dropstone event coincides with marked shifts in organic geochemis try of the associated marine shale as well as changes in foraminiferal productivity. The implied cool-climate event may have only been a sho rt-term climatic oscillation, perhaps of only thousands of years. Howe ver, it was significant enough to have affected the biota and organic matter in the water column. The dropstones may represent a deep-water example of a correlative conformity referred to in sequence stratigrap hy literature. Although the dropstones are easily recognizable in the sediments, the interpretation relies on associated palaeontological an d organic geochemical data. Sea-level curves presented elsewhere in th e literature show mid-Paleocene sea-level falls which approximately co incide with the time when the dropstones in eastern New Zealand were d eposited.