کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5784365 1639062 2017 20 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Formation of sediment waves by turbidity currents and geostrophic flows: A discussion
ترجمه فارسی عنوان
شکل گیری امواج رسوب برحسب جریان های مختلط و جابجایی جغرافیایی: یک بحث
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
چکیده انگلیسی
A condition for the existence of sediment waves under turbidity currents as antidunes with the requirement of a slope gradient ≥ 3.0 × 10− 3 is deduced. Data show no such waves on slopes < 2.5 × 10− 3, but some contourite mudwaves occur on slopes as low as 4.4 × 10− 4. However the latter also occur on slopes > 3 × 10− 3 so no clear distinction is possible. Where turbidity current channels cross sediment drifts, or geostrophic flows traverse turbidite fans, the origin of most mudwaves will need to be determined by reference to internal features and context. A key problem is deposition of mud as antidunes from turbidity currents where even the waning flow is probably well above the critical erosion velocity for a clear flow. Deposition must occur from high concentration flows well above clear water critical depositional stresses. Once a wavy bed is set up, subsequent deposition may occur via the lee-wave mechanism proposed for contourite waves under a gradient Froude Number > 1. A steep angle (< 45°) between crest and flow axes is typical of GF waves, which may be dunes or antidunes, whereas TC waves tend to be orthogonal, but data on this discriminant are sparse.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Marine Geology - Volume 390, 1 August 2017, Pages 89-93
نویسندگان
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