کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5786022 | 1640330 | 2017 | 65 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Petrography and geochemistry of Cenozoic sedimentary sequences of the southern Samar Island, Philippines: Clues to the unroofing history of an ancient subduction zone
ترجمه فارسی عنوان
پتروگرافی و ژئوشیمی توالی های رسوبی کانوزوئیک جزیره جنوبی سامار، فیلیپین: نشانه هایی از تاریخ پیدایش ناحیه فرورانش باستان
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کلمات کلیدی
پروانه، زیرزمین افیولیت، منطقه فرورانش باستان، فیلیپین،
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
زمین شناسی
چکیده انگلیسی
The Cenozoic sedimentary sequences of southern Samar Island in eastern Philippines were examined to understand the unroofing history of an ancient arc terrane. Petrographic and geochemical data revealed varying degrees of inputs from the ophiolite basement and differences in modal compositions. The sedimentary units are mostly made up of lithic fragments. The Late Oligocene to Early Miocene Daram Formation contains more chert and volcanic fragments whereas the late Middle Miocene to Early Pliocene Catbalogan Formation is dominantly composed of ultramafic components. These variances are correspondingly reflected in the geochemical signatures of these two sedimentary formations. The Catbalogan Formation clastic rocks have higher volatile-free MgO and Fe2O3 values (average: 8.4% for both oxides) compared to the Daram Formation samples (average: 5.1 and 6.3%, respectively). Geochemical variations are also reflected in the Co, Cr and Ni values: the Catbalogan Formation samples reflect higher concentrations (Co: 15-57Â ppm; Cr: 231-1094Â ppm; Ni: 84-484Â ppm) compared to the Daram Formation samples (Co: 24-32Â ppm; Cr: 234-418Â ppm; Ni: 212-323Â ppm). These observations suggest that the Daram Formation eroded and transported more of the crustal portions of the ophiolite, while the younger Catbalogan Formation represents a later exhumation and subsequent erosion of the ultramafic section. An oceanic island arc (OIA) setting is proposed for the two formations based on several tectonic discrimination diagrams (e.g., Th-La-Sc, La vs. Th). The OIA signature is further supported by their smooth chondrite-normalized rare earth element (REE) patterns with no obvious Eu anomaly as well as LREE enrichment which are typical of sediments deposited in OIA setting. Based on the dominantly ophiolitic provenance of the Daram and Catbalogan formations, the post-emplacement history of the nearby Samar Ophiolite is constrained during the Late Oligocene to Early Pliocene period.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Asian Earth Sciences - Volume 142, July 2017, Pages 3-19
Journal: Journal of Asian Earth Sciences - Volume 142, July 2017, Pages 3-19
نویسندگان
Nichole Anthony D. Pacle, Carla B. Dimalanta, Noelynna T. Ramos, Betchaida D. Payot, Decibel V. Faustino-Eslava, Karlo L. Queaño, Graciano P. Jr.,