11 research outputs found
The application of geospatial interpolation methods in the reconstruction of Quaternary landform records
An integrated field and numerical modelling study of controls on Late Quaternary fluvial landscape development (Tabernas, southeast Spain)
Single-grain and multi-grain OSL dating of river terrace sediments in the Tabernas Basin, SE Spain
River terraces represent important records of landscape response to e.g. base-level change and tectonicmovement. Both these driving forces are important in the southern Iberian Peninsula. In this study,Optically Stimulated Luminescence (OSL) dating was used to date two principal river terraces in theTabernas Basin, SE Spain. A total of 23 samples was collected from the fluvial terraces for dating usingquartz OSL. Sixteen of the samples could not be dated because of low saturation levels (e.g. typical2xD0 < 50 Gy). The remaining seven samples (5 fossil and 2 modern analogues) were investigated usingboth multi-grain and single-grain analysis. Single grain results show that: (i) measurements from multigrainaliquots overestimate ages by up to ~ 4 ka for modern analogues and young samples (<5 ka),presumably because (ii) the presence of many saturated grains has biased the multi-grain results to olderages. Despite the unfavourable luminescence characteristics we are able to present the first numerical agesfor two terrace aggradation stages in the Tabernas Basin, one at ~16 ka and the other within the last 2 ka.© 2015 Elsevier B.V. All rights reserved
Controls on dryland mountain landscape development along the NW Saharan desert margin: Insights from Quaternary river terrace sequences (Dadès River, south-central High Atlas, Morocco)
This study documents river terraces from upstream reaches of the Dadès 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
