Paleomagnetic Investigation of Pacific Ocean Rises

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The Cretaceous Long Normal Polarity Chron (83-119 Ma) represents a 35 million year 'blind' spot in Pacific basin plate motion models based on marine magnetic anomalies. To constrain the evolution of the Pacific basin. This study will be a detailed paleomagnetic and paleontologic analysis of Cretaceous limestones from ten Pacific DSDP oceanic rise sites. The study differs in a fundamental way from much of the previous Pacific paleomagnetic DSDP studies. Rather than studying basalts and producing a paleolatitude value for a given site at only a single age, the emphasis is on DSDP limestones which would yield several Paleolatitude values corresponding to a range of geologicages during which the limestone was deposited. A key feature of this collaborative research is the development and use of a high-resolution biostratigraphic zonation for planktonic foraminifera studied in thin sections. As a result, the Cretaceous limestones can be dated with increased precision and can be correlated with key biostratigraphic sections previously dated by foraminifera in this section. Using automated facilities of the Stanford Paleomagnetic Laboratory and improved measurement techniques, it will be possible to obtain very rapidly paleolatitude information from various DSDP sites. The results will help to interpret in detail the plate motions in the Pacific during the Cretaceous Long Normal Polarity Event.