Arid
DOI10.1016/j.sedgeo.2009.11.002
Glaciation and deglaciation of the Libyan Desert: The Late Ordovician record
Le Heron, D. P.1; Armstrong, H. A.2; Wilson, C.2; Howard, J. P.3; Gindre, L.4
通讯作者Le Heron, D. P.
来源期刊SEDIMENTARY GEOLOGY
ISSN0037-0738
出版年2010
卷号223期号:1-2页码:100-125
英文摘要

Detailed outcrop studies at the flanks of Al Kufrah Basin, Libya, reveal the nature of glacially-related sedimentation and post-depositional deformation styles produced in association with the Late Ordovician glaciation, during which ice sheets expanded northward over North Africa to deposit the Mamuniyat Formation. At the SE basin flank (Jabal Azbah), the Mamuniyat Formation is sand-dominated, and incises interfingering braidplain and shallow marine deposits of the Hawaz Formation. The glacially-related sediments include intercalations of mud-chip bearing tabular sandstones and intraformational conglomerates, which are interpreted as turbidite and debrite facies respectively. These record aggradation of an extensive sediment wedge in front of a stable former ice margin. An increase in mudstone content northward is accompanied by the occurrence of more evolved turbidites. A widespread surface, bearing streamlined NW-SE striking ridges and grooves, punctuates this succession. The structures on the surface are interpreted to have formed during a regional north-westward ice advance. Above, siltstones bearing Arthrophycus burrows, and Orthocone-bearing sandstones beneath tidal bars testify to glaciomarine conditions for deposition of the underflow deposits beneath. By contrast, the northern basin margin (Jabal az-Zalmah) is appreciably different in recording shallower water/paralic sedimentation styles and major glaciotectonic deformation features, although facies analysis also reveals northward deepening. Here, a siltstone wedging from 8 to 50 m toward the north was deposited (lower delta plain), succeeded by climbing ripple cross-laminated sandstones up to 60 m in thickness (distal through proximal delta mouth bar deposits) with occasional diamictite interbeds. These rocks are deformed by thrusts and > 50 m amplitude fault-propagation folds, the deformation locally sealed by a diamictite then overlain by conglomeratic lag during ultimate deglaciation. Integrating observations from both basin margins, a model of fluvial-dominated delta systems feeding a pulsed debrite and turbidite fan system in a shallow proglacial shelf is proposed. (c) 2009 Elsevier B.V. All rights reserved.


英文关键词Glacial North Africa Ordovician Reservoir
类型Review
语种英语
国家England ; Norway
收录类别SCI-E
WOS记录号WOS:000274546500008
WOS关键词BASIN SE LIBYA ; ICE-SHEET ; MURZUQ BASIN ; TUNNEL VALLEYS ; NORTH-SEA ; TURBIDITY CURRENTS ; LINKED DEBRITES ; MASS EXTINCTION ; GROUNDING-LINE ; SAUDI-ARABIA
WOS类目Geology
WOS研究方向Geology
来源机构University of London
资源类型期刊论文
条目标识符http://119.78.100.177/qdio/handle/2XILL650/166378
作者单位1.Royal Holloway Univ London, Dept Earth Sci, Egham TW20 0EX, Surrey, England;
2.Univ Durham, Dept Earth Sci, Sci Labs, Durham DH1 3LE, England;
3.CASP, Cambridge CB3 0DH, England;
4.StatoilHydro ASA, Res Ctr, N-7005 Trondheim, Norway
推荐引用方式
GB/T 7714
Le Heron, D. P.,Armstrong, H. A.,Wilson, C.,et al. Glaciation and deglaciation of the Libyan Desert: The Late Ordovician record[J]. University of London,2010,223(1-2):100-125.
APA Le Heron, D. P.,Armstrong, H. A.,Wilson, C.,Howard, J. P.,&Gindre, L..(2010).Glaciation and deglaciation of the Libyan Desert: The Late Ordovician record.SEDIMENTARY GEOLOGY,223(1-2),100-125.
MLA Le Heron, D. P.,et al."Glaciation and deglaciation of the Libyan Desert: The Late Ordovician record".SEDIMENTARY GEOLOGY 223.1-2(2010):100-125.
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