کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4689153 | 1636034 | 2015 | 72 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Giant scour-fills in ancient channel-lobe transition zones: Formative processes and depositional architecture
ترجمه فارسی عنوان
مگس غول پیکر در ناحیه های گذرا در کانال های باستانی پر شده است: فرآیندهای شکل گیری و معماری رسوب
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کلمات کلیدی
انتقال کانال لوب، پایه شیب، پودر غول پیکر، مایع پر کردن، میان بر، حوضه کارو،
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
فرآیندهای سطح زمین
چکیده انگلیسی
Scours are common features of modern deep-marine seascapes, particularly downstream of the mouths of slope channels within channel-lobe transition zones (CLTZs). Their dimensions can exceed hundreds of metres in width and length, and tens of metres in depth. However, the stratigraphic architecture of large (>Â 100Â m width) scours have not been described in detail from exhumed CLTZs. Here, the infill of two erosional features (0.5-1Â km long and 15-20Â m thick) from the Permian Karoo Basin succession, South Africa, are presented from palaeogeographically well-constrained CLTZs; one from Fan 3 in the Tanqua depocentre and one from Unit A5 in the Laingsburg depocentre. The basal erosion surfaces of the features are asymmetric with steep, undulating, and composite upstream margins, and low gradient simple downstream margins. The basal infill consists of thin-bedded siltstone and sandstone beds cut by closely-spaced scours; these beds are interpreted as partially reworked fine grained tails of bypassing flows with evidence for flow deflection. The erosional features are interpreted as giant scour-fills. The Unit A5 scour-fill shows a simple cut-and-fill history with lateral and upward transitions from siltstone- to sandstone-prone deposits. In contrast, the Fan 3 scour-fill shows headward erosion and lengthening of the scour surface suggesting temporal changes in the interaction between turbidity currents and the scour surface. This relationship could support the occurrence of a hydraulic jump during scour formation, whilst the majority of the fill represents deposition from subcritical flows. Different scour preservation mechanisms can be used to explain the style of infill. The architecture, sedimentary facies and palaeoflow patterns of the scour-fills are distinctly different from well documented adjacent basin-floor channel-fills at the same stratigraphic levels. The recognition of scour-fills helps to constrain their sedimentological and stratigraphic expression in the subsurface, and to improve our understanding of the stratigraphic architecture of channel-lobe transition zones.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Sedimentary Geology - Volume 329, November 2015, Pages 98-114
Journal: Sedimentary Geology - Volume 329, November 2015, Pages 98-114
نویسندگان
M. Hofstra, D.M. Hodgson, J. Peakall, S.S. Flint,