000031671 001__ 31671
000031671 041__ $$aEnglish
000031671 100__ $$aQiang, M.
000031671 245__ $$aLate Pleistocene and Holocene Aeolian Sedimentation in Gonghe Basin, Northeastern Qinghai-Tibetan Plateau: Variability, Processes, and Climatic Implications
000031671 260__ $$c2016
000031671 300__ $$a57-73
000031671 520__ $$aAlthough stratigraphic sequences of aeolian deposits in dryland areas have long been recognized as providing information about past environments, the exact nature of the environmental processes they reflect remains unclear. Here, we report the results of a detailed investigation of eight outcrop sections in the Gonghe Basin, northeastern Qinghai-Tibetan Plateau. Measurements of sediment grain-size and chemical composition indicate that the deposits are primarily of aeolian origin, consisting of interbedded, well-sorted sand, silty sand, loess and/or palaeosol; however, their occurrence varies from site to site. Fossil dune sands mainly occur in or close to the currently stabilized or semi-stabilized dune fields, whereas loess is distributed along the downwind marginal areas. This pattern of basin-scale differentiation was controlled mainly by spatial variability of sediment supply due to the antecedent sedimentary patterns within the basin. Together with previously-published optically stimulated luminescence (OSL) ages, 24 new OSL dates are used to elucidate the history of aeolian activity and its relationship to climatic changes. There is no apparent relationship between past dune activity and downwind loess deposits. Deposition of silty sand probably occurred during past phases of windy, dry and cold climate in the Late Pleistocene. However, climatic factors alone cannot explain the occurrence of silty sand deposition. This is because the deposition of silty sand was always preceded by episodes of fluvial deposition prior to river incision, thereby indicating the importance of an ˜activated™ sediment supply associated with fluvial processes. Deposition of well-sorted sand occurred episodically, not only during the Late Pleistocene, but also during the early- to mid-Holocene. Vegetation conditions, controlled either by the occurrence of intervals of moisture deficit during the Late Pleistocene or by changes in the balance between precipitation and evapotranspiration at a local scale, played an important role in sand mobility and deposition. The effect of vegetation on sand mobility is also suggested by independent evidence of aeolian activity from Genggahai Lake in the Gonghe Basin. Here, the deposition of aeolian sand in the basin during the early- to mid-Holocene indicates a low level of effective moisture caused by high evaporation induced by higher summer insolation, despite the coeval increased regional precipitation recorded by lacustrine sediments. In contrast, late Holocene palaeosols represent a high level of effective moisture, and their formation did not necessarily require increased regional precipitation. Overall, our results suggest that the relationship between aeolian activity and regional climate change is complex, and that sand accumulations do not represent the consistent action of surface processes that are related to climatic changes.
000031671 653__ $$aAeolian Activity
000031671 653__ $$aSand Accumulation
000031671 653__ $$aVegetation Condition
000031671 653__ $$aSediment Supply
000031671 653__ $$aLuminescence Dating
000031671 653__ $$aClimatic Change
000031671 653__ $$aGonghe Basin
000031671 653__ $$aChina
000031671 700__ $$aJin, Y.
000031671 700__ $$aLiu, X.
000031671 700__ $$aSong, L.
000031671 700__ $$aLi, H.
000031671 700__ $$aLi, F.
000031671 700__ $$aChen, F.
000031671 773__ $$pQuaternary Science Reviews
000031671 773__ $$v132 
000031671 773__ $$ahttp://dx.doi.org/10.1016/j.quascirev.2015.11.010
000031671 8564_ $$uhttp://www.sciencedirect.com/science/article/pii/S027737911530175X$$yExternal link (open access)
000031671 980__ $$aARTICLE