Controls on dryland mountain landscape development along the NW Saharan desert margin: Insights from Quaternary river terrace sequences (Dades River, south-central High Atlas, Morocco)

被引：53

作者：

Stokes, M. ^{[1
]}

Mather, A. E. ^{[1
]}

Belfoul, M. ^{[2
]}

Faik, F. ^{[2
]}

Bouzid, S. ^{[2
]}

Geach, M. R. ^{[1
,3
,6
,7
]}

Cunha, P. P. ^{[4
]}

Boulton, S. J. ^{[1
]}

Thiel, C. ^{[5
,6
,7
]}

机构：

[1] Plymouth Univ, Sch Geog Earth & Environm Sci, Drake Circus, Plymouth PL4 8AA, Devon, England

[2] Ibn Zohr Univ, Fac Sci, Earth Sci Dept, Struct Geol & Themat Mapping Lab, POB 8106, Hay Dakhla 80000, Agadir, Morocco

[3] ATKINS, Woodcote Grove, Ashley Rd, Epsom KT18 5BW, Surrey, England

[4] Univ Coimbra, Marine & Environm Sci Ctr, Dept Earth Sci, Coimbra, Portugal

[5] Leibniz Inst Angew Geophys, Stilleweg 2, D-30655 Hannover, Germany

[6] Aarhus Univ, Nord Lab Luminescence Dating, Riso Campus, Aarhus, Denmark

[7] Tech Univ Denmark DTU, Ctr Nucl Technol, Riso Campus, Lyngby, Denmark

来源：

QUATERNARY SCIENCE REVIEWS | 2017年 / 166卷

关键词：

Pleistocene; Climate dynamics; Paleogeography; Africa; Fluvial geomorphology; Optical methods; OUARZAZATE FORELAND BASIN; FLUVIAL INCISION; BELT DADES; EVOLUTION; DEPOSITS; CLIMATE; QUARTZ; SEDIMENTATION; PLEISTOCENE; BEDROCK;

D O I：

10.1016/j.quascirev.2017.04.017

中图分类号：

P9 [自然地理学];

学科分类号：

0705 ; 070501 ;

摘要：

This study documents river terraces from upstream reaches of the Dades River, a major fluvial system draining the south-central High Atlas Mountains. Terraces occur as straths with bedrock bases positioned at 10 m altitudinal intervals up to 40 m (T1-T5) above the valley floor, becoming less common between 50 and 140 m. The rock strength, stratigraphy and structure of the mountain belt influences terrace distribution. Terraces are absent in river gorges of structurally thickened limestone; whilst well developed, laterally continuous terraces (T1-T4) form along wide valleys occupying syncline structures dominated by weaker interbedded limestone-mudstone. Terrace staircases develop in confined canyons associated with weaker lithologies and influence from structural dip and stratigraphic configuration. Terraces comprise a bedrock erosion surface overlain by fluvial conglomerates, rare overbank sands and colluvium. This sequence with some OSL/IRSL age control, suggests terrace formation over a 100 ka climate cycle with valley floor aggradation during full glacials and incision during glacial-interglacial transitions. This integrates with other archives (e.g. lakes, glaciers, dunes), appearing typical of landscape development along the NW Saharan margin south of the High Atlas, and similar to patterns in the western-southern Mediterranean. The 100 ka climate cycle relationship suggests that the terrace sequence documents Late-Middle Pleistocene landscape development. Consistent altitudinal spacing of terraces and their distribution throughout the orogen suggests sustained base-level lowering linked to uplift-exhumation of the High Atlas. Low incision rates (< 0.2 mm a(-1)) and general absence of terrace deformation suggests dominance of isostatically driven base-level lowering with relief generation being Early Pleistocene or older. (C) 2017 Elsevier Ltd. All rights reserved.

引用

页码：363 / 379

页数：17