Emplacement of the Zambales Ophiolite into the West Luzon Margin
Published:January 01, 1982
The Zambales Ophiolite in western Luzon is a large fragment of oceanic crust that was uplifted several kilometers without being obducted onto a continental margin. Deposition of pelagic limestone on the ophiolite during the late Eocene through Oligocene gave way to deposition of ophiolite-derived clastics during the early Miocene. The uplift of the western edge of the ophiolite probably was related to the initiation of subduction along the Manila Trench in the late Oligocene, but the Zambales crust predates the oldest crust in the adjacent South China Basin by about 8 million years. A new sandstone petrology method traces the uplift and erosional history of the ophiolite through the changing compositions of the ophiolite-derived clastics.
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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.