Nature and Origin of Deep-Sea Carbonate Nodules Collected from the Japan Trench
Published:January 01, 1982
IPOD/DSDP Leg 50 collected 18 carbonate nodules drilling the inner trench slope of the Japan Trench. They found the nodules in the sedimentary sequence deeper than 180 m where abundant methane occurs. The carbonate minerals in the nodules were comprised of magnesian calcite, dolomite, manganese calcite, and rhodochrosite. Petrographic evidence and oxygen and carbon isotopic compositions show that these carbonate nodules were authigenically formed at or near the position where they were found. Carbon isotopic compositions of many of these nodules reveal that the carbon in carbonate nodules may have been derived from carbon dioxide evolved during the sulfate...
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Studies in Continental Margin Geology
"Studies in Continental Margin Geology" contains papers from a research conference co-sponsored by AAPG and the University of Texas Institute for Geophysics held in Galveston, Texas in 1981. Rapid advances in the understanding of continental margin geology were taking place during the time period, based on major improvements in the quality and availability of regional seismic surveys plus other fields such as organic geochemistry. For the first time it was becoming common to have a visual characterization of tectonic processes at significant depths below the surface. Twenty-seven papers are presented that deal with field investigations of continental margin structure and stratigraphy. The geographic areas of study are global in nature and many of the descriptive results are derived from modern seismic investigations in areas where that type of data had not previously been available in commercial publications. Fifteen of the papers focus on rifted margins and the other twelve concern convergent margins. Twelve papers are model investigations of a variety of margin environmental processes, related to subjects such as depositional environments, biostratigraphy, organic matter deposition, and oil and gas occurrences as a function of the plate tectonic setting. An additional nine papers model the thermal and mechanical tectonic processes involved in the structural development along continental margins.