Rekonstruktion der Subduktion des Yakutat-Terranes anhand der tektonischen Entwicklung des Kodiak- und Middleton-Schelfs im nördlichen Golf von Alaska : eine regionale Studie über den Einfluß plattentektonischer Ereignisse auf das strukturelle Bild einer konvergenten Plattengrenze
A model describing the Cenozoic migration of the Yakutat Terrane, a composite oceanic and continental tectonostratigraphic terrane of the Gulf of Alaska, and its entry into the Alaskan subduction zone is developed here. The model includes new data and results acquired during the cruise SO 96-2 KODIA...
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| Format: | Thesis |
| Language: | German |
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1995
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| Online Access: | https://oceanrep.geomar.de/id/eprint/59125/ https://oceanrep.geomar.de/id/eprint/59125/1/Diss_Dethloff_R_1995.pdf |
| Summary: | A model describing the Cenozoic migration of the Yakutat Terrane, a composite oceanic and continental tectonostratigraphic terrane of the Gulf of Alaska, and its entry into the Alaskan subduction zone is developed here. The model includes new data and results acquired during the cruise SO 96-2 KODIAKSEIS with the German R/V SONNE in 1994. A review of various geophysical data sets (seismic reflection and refraction sections, free-air gravity) in combination with the results from geologic analyses (basin analysis techniques, plate tectonic modeling, geomorphologic interpretations) provides constraints on the collision of the Yakutat Terrane with the convergent margin of the eastern Gulf of Alaska. The correspondence between regional tectonism of the Kodiak and Middleton shelves and the subduction of the Yakutat Terrane suggests a cause-and-effect relationship that is constrained by the timing of tectonic events and the uplift / subsidence history along the fore-arc. The basaltic basement of the Yakutat Terrane originated on seamounts near the Kula-Farallon spreading center during the early to middle Eocene. Coeval and geochemically similar basalts, occuring in a linear accreted belt from southern Vancouver Island to the southern Oregon Coast Range, are correlative with the Yakutat Terrane basalts. It is likely that the northward migration of the Yakutat Terrane started from a position seaward of N-Washington and Vancouver Island sometime between the middle to late Eocene. During its northward movement close to the coast of British Columbia and southeast Alaska, voluminous elastic sediments that originated from the uplifted regions of the coastal batholithic complex were shed on its composite basement and the adjacent abyssal plain of the Kula plate. Simultaneously, the development of the Zodiac fan located southwest Yakutat Terrane started about 42 Ma and from the late Oligocene (24 Ma) the western part of the Surveyor fan began to form. The now-subducted western portion of the Yakutat Terrane bridged the gap ... |
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