کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6441578 | 1639087 | 2015 | 9 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Seismic evidence for crustal underplating beneath a large igneous province: The Sierra Leone Rise, equatorial Atlantic
ترجمه فارسی عنوان
شواهد لرزه ای برای زیر پوسته زیر یک استان آذربایجان بزرگ: سیرالئون ظهور، استوایی اقیانوس اطلس
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کلمات کلیدی
استان آذربایجان غربی، ساختار لرزه ای، زیرین پوسته، زیرپوشش ماگمایی، نقاط داغ اقیانوس اطلس،
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
چکیده انگلیسی
Wide-angle seismic profiles reveal anomalously thick crust with a high-velocity (> 7.3 km sâ 1) zone under the Sierra Leone Rise, a major mid-plate elevation in the Atlantic lying between the Cape Verde platform and the Cameroon Volcanic Line. A profile recorded over the crest using an ocean-bottom seismometer and surface sonobuoys shows that beneath a 3 km water layer and 1 km of sediments, the basement extends to 16-20 km below sea level. Most velocity-depth values fall outside the expected range for Mesozoic-early Cenozoic ocean floor and stretched continental crust. The detection of 7.3-7.5 km sâ 1 material beneath thick, lower-velocity volcanics suggests that magmatic underplating of the crust has occurred. A prominent change in velocity gradient 10-12 km below sea level may mark the transition to underplated material emplaced during the late Cretaceous-early Cenozoic. A pronounced change in Moho depth lies on the line of a long offset fracture zone extending from the African margin, implying underplating was influenced by a pre-existing discontinuity in the lithosphere. Other seismic lines show 7.0-7.2 km sâ 1 basement above the underplated zone extending into water depths of almost 5 km. This is probably the intrusive foundation of early-formed crust over a mantle hot-spot. It is suggested that the development of the Sierra Leone Rise is distinct from other Atlantic hot-spot features to which it has been linked because of its setting in a region of intense lithospheric shear.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Marine Geology - Volume 365, 1 July 2015, Pages 52-60
Journal: Marine Geology - Volume 365, 1 July 2015, Pages 52-60
نویسندگان
E. John W. Jones, George A. McMechan, Xiaoxian Zeng,