کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
8912099 1639059 2017 41 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Slope instability on a shallow contourite-dominated continental margin, southeastern Grand Banks, eastern Canada
ترجمه فارسی عنوان
بی ثباتی شیب در حاشیه قاره حاشیه کم عمق، جنوب شرقی بانک های بزرگ، شرق کانادا
کلمات کلیدی
سپرده های حمل و نقل عمومی، جاروبرقی جیوه-جریان، هاینریش لایه ها، بانک های شمال شرقی شمال، زمین لغزش های زیردریایی، محدودیت آتتربرگ، آزمون سه تایی،
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
چکیده انگلیسی
Submarine sediment failures and related mass-transport deposits (MTDs) are widespread on the eastern Canadian continental slope settings and in general, have been related to ice sheets crossing the outer shelf. The southeastern Grand Banks margin was not glaciated in the last 105 years and has a deep shelf break. As a result, the upper continental slope consists principally of sediment transported from the north by the Labrador Current. High-resolution seismic profiles and 10-m long piston cores show widespread sediment failure and MTDs in a plastered contourite drift from 500 to 1000 m water depth. This study documents the stratigraphy of the past 48,000 years and the record of sediment failure events. Heinrich layers H1 to H5 have been recognized from distinctive petrology, physical properties, and bulk geochemistry and are constrained by numerous 14C-AMS dates. The geotechnical analysis shows that the latest Quaternary sediment section is mildly underconsolidated, perhaps related to high sedimentation rates (up to 0.5 m/ka) enhanced by some leakage of deep fluids. Nevertheless, factor of safety calculations using Su/P0 and friction angles from triaxial testing suggest the slope is statically stable up to gradients of 9°. Atterberg limit measurements of silty contourite sediments indicate susceptibility to liquefaction under cyclic loading. There is evidence that apparently synchronous failure occurred over many tens of kilometres of the slope, probably as a result of rare passive margin earthquakes. These shallow water contourite deposits have a higher sand and coarse silt content, much less biogenic material, and more rapid variations in sediment and geotechnical properties than those of the deep-water equivalents, all of which make them more susceptible to sediment failure.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Marine Geology - Volume 393, 1 November 2017, Pages 203-215
نویسندگان
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