Basic Study of Paleoceanographic Reconstruction by Marine Ferro-manganese Crusts.

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Marine ferromanganese oxide precipitates covering the rock outcrops are regarded as a possible long-range paleoceanographic indicator, as well as future mineral resources, but little study has been done based on fine-scale dating and physical and chemical description. We attempted the microstratigrahic description of hydrogenetic ferromanganese crusts dispersed over the western Pacific ocean floors. We found fairly good correlation of the microstratigraphy of some crusts remotely located each other, which indicates the lateral wide influence of bottom and intermediate waters through the geologic time. By contrast, the stratigraphy is much different in the crusts between the close locations at different depths.The fine-scale age dating of ferromanganese crusts is one of the most important marine geological science fields. We compared fine the paleomagnetic reversal patterns and Berilium-10 radiochemical dating and possible coincidence, which is proved to be another reliable tool for dating. We are ready to analyze the finely polished crusts using the Super-conductor magnetometer (SQUID) to determine the exact point of magnetic reversal at 780000yr (planned at CALTEC on June 2005). Furthermore, we examined the thermal demagnetization process of the hydrogentic crusts and obtained important information about the carrier mineral of the magnetism of the crusts.In future, we continue to study this topic to ensure the reliability of magnetic stratigraphy and reconstruction of past oceanographic and geological environments.