Print this pageThe Hemispheric Asymmetry of the Marine Stratigraphic Record: Proof of a Polar Icecap
PERLMUTTER, MARTIN A., and ROY E. PLOTNICK
Recent preliminary confirmation of the Exxon sea level chart indicates possible episodes of glaciation during times when none were thought to have existed. Our work suggests that the presence of a polar icecap can be confirmed by establishing the asymmetry in the thicknesses of the marine stratigraphic record of the northern and southern hemispheres produced by the interaction of precession-scale sediment yield and glacioeustatic cycles. Hemispheric asymmetry should not exist in an ice free world. If our hypothesis is correct, it will permit substantial refinements in interpreting the stratigraphic record, leading to refined exploration techniques.
In periods of unipolar glaciation, higher sea level will occur during the precessional climate maximum in the glaciated hemisphere, when the opposing hemisphere is at a precessional climate minimum. Through most of the Phanerozoic, until the Plio-Pleistocene, large landmasses in polar latitudes occurred predominantly in the southern hemisphere, precluding a large northern polar glacier. When ice did exist at the southern pole, the southern hemisphere precessional climatic maximum coincided with sea level highstands, while the northern hemisphere precessional climatic maximum coincided with sea level lowstands. Sediment yield cycles from areas with the same climatic succession but located in opposite hemispheres will have two distinct phase relationships with glacioeustasy, creating different stratigraphic architectures. This will produce statistically different patterns of bed thickness distributions.