کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
6350470 1622216 2013 18 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Subglacial to proglacial depositional environments in an Ordovician glacial tunnel valley, Alnif, Morocco
ترجمه فارسی عنوان
محدوده های زیر زمینی به محیط رسوب گذار در یک دره تونل یخچالی اردوویکی، آلنف، مراکش
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فرآیندهای سطح زمین
چکیده انگلیسی

This paper presents the sedimentary analysis of an exceptional Ordovician glacial tunnel valley in the eastern part of the Anti-Atlas. The valley infill comprises two major glacial erosion surfaces (striated pavements) each overlain by a fining-upward glacial unit. These units are composed of five distinct facies associations, recording the evolution from subglacial to proglacial environments, and an additional sixth facies association, overtopping the tunnel valley infill, and associated with post-glacial environments. The tunnel valley infill also records a transitional environment between the subglacial and proglacial settings, which is compared with the Antarctic ice-sheet margin. These three environments are defined by the position of the grounding line and the coupling line. The new proposed depositional model also differs from usual Ordovician depositional models in which the main tunnel valley infill is interpreted as essentially proglacial outwash deposits, in a range of glaciomarine to glaciofluvial environments. Overall, a substantial part of the valley infill (~ 50% of volume) was deposited in a subglacial setting. The sedimentary bodies could form potentially thick and laterally extended, although these were limited by the shape and extent of the subglacial accommodation space. Finally, the sedimentary record, when compared with regional analogues, also provides information for the palaeogeographic reconstruction of the Ordovician ice-sheet in this region.

► An Ordovician tunnel valley infill is described in detail. ► Subglacial and proglacial depositional environments are determined. ► An additional environment is proposed associated with a lightly grounded ice-sheet. ► Accommodation space is defined for proglacial and subglacial settings. ► The study provides additional data for Hirnantian ice-sheet reconstruction.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Palaeogeography, Palaeoclimatology, Palaeoecology - Volume 370, 15 January 2013, Pages 127-144
نویسندگان
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