Two sediment cores recovered in the central part of Daihai Lake in north-central China were analysed at 2-to 4-cm intervals for total inorganic and organic carbon (TIC and TOC) concentrations. The TIC concentration is inferred to reflect temperatures over the lake region and an increase in the TIC concentration implies an increase in the temperature. TOC concentration is considered to reflect the precipitation in the lake basin and higher TOC concentrations denote more precipitations. Thus AMS 14C time series of the TIC and TOC records of Daihai Lake sediments uncovers a detailed history of changes in temperature and precipitation in north-central China during the last c. 12 000 yr. The Holocene, an epoch of postglacial warmth, started c. 11 500 cal. yr BP, and can be subdivided into three stages: the early (c. 11 500-8100 cal. yr BP), middle (c. 8100-3300 cal. yr BP) and the late Holocene (c. 3300-0 cal. yr BP). The climate was warm and dry during the early Holocene, warm and wet during the middle Holocene, and in the late Holocene became cooler and drier but displayed a relatively warmer and wetter interval between c. 1700 and 1300 cal. yr BP. The Holocene Climatic Optimum, defined as a postglacial episode of both megathermal and megahumid climate, might have occurred in north-central China between c. 8100 and 3300 cal. yr BP, and the climate during this period was variable and punctuated by cool and/or dry events. We infer that changes in the temperature were directly controlled by changes in summer solar radiation in the Northern Hemisphere resulting from progressive changes in the Earth's orbital parameters. Whereas an increase in the monsoonal precipitation could be closely related to an increase in the sea surface temperature of the low-latitude Pacific Ocean, an increase in the temperature and size of the Western Pacific Warm Pool and a westward shifted and strengthened Kuroshio Current in the western Pacific.
As a latest Pleistocene repository of Indus River sand at the entry point to the Himalayan foreland basin, the Thal dune field in northern Pakistan stores crucial information that can be used to reconstruct the erosional evolution of the Himalayan-Karakorum orogen and the changes in the foreland-basin landscape that took place between the Last Glacial Maximum and the early Holocene.This comprehensive provenance study of Thal Desert sand integrates previously existing petrographic, heavy-mineral, mineral-chemical, isotopic, and geochronological databases with original bulksediment geochemistry, zircon-age, and Nd-isotope data. Dune sand is low in quartz and rich in feldspars, volcanic, metavolcanic and metabasite grains, contains a very rich transparent heavymineral suite including hypersthene and common zircon grains dated as Late Cretaceous to early Paleogene, and is characterized by high Mg, Sc, V, Co, Ni, Cu concentrations and by Nd values as high as -3.5. Together, these data indicate that ~40% of Thal dune sand was supplied by erosion of the Kohistan arc, a proportion that far exceeds the one assessed for modern Upper Indus sand. Greater detrital supply from the Kohistan arc indicates notably different conditions of sediment generation, during a period in which the sediment-transport capacity of the Upper Indus in the dry lowlands was reduced and volumes of sand were extensively reworked by wind and accumulated in dune fields across the foreland basin. In the early Holocene, the renewed strength of the South Asian monsoon and consequently markedly increased water and sediment discharge led to incision of the Thal and Thar dune fields by the Indus River and its Punjab tributaries draining the Himalayan front directly hit by heavy monsoonal rains.
Introduction 1 2The western Himalaya and Karakorum Ranges (in Sanskrit: hima = snow, alayah = abode; in 3 Uyghur Turkic: kara = black, korum = gravel) drained by the Indus River provide a spectacular 4 example of an orogenic belt produced by continental collision . Ongoing indentation 5
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