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• Two thermal events proposed for the Linzizong Group in the Linzhou basin are invalid. • The lower Linzizong volcanic rocks preserve primary igneous texture and paleomagnetic signals. • The cooling rates of the Linzizong volcanic rocks are comparable. • The notion of the high topography of Gangdese cannot be refuted by thermochronological data. [ABSTRACT FROM AUTHOR]

Abstract: Due to marine recession and stepwise uplift of the Tibetan Plateau during the Cenozoic era, an extremely arid environment and large deserts developed progressively in the interior of Asia. The Tarim Basin is a typical region that experienced this type of palaeoenvironmental evolution. In this study, we apply high resolution palaeomagnetic dating, ESR dating and palaeoenvironmental reconstruction to two parallel sections from an almost 1000m thick sequence of terrestrial sediments in the central Tarim Basin in order to characterize and date the process of drying and desertification. Our results indicate that the western Tarim Basin started to accumulate terrestrial sediments in a dry land environment at the latest by ~4.2Ma, and that the initial desert was formed by ~3.4Ma from fluvial sands originating from the Tibetan Plateau when the climate became particularly dry in the interior of Asia due to the uplift of the Tibetan Plateau. Variations of the stratum properties, including colour index and magnetic susceptibility, indicate that the aridification trend was significantly intensified at ~2.6Ma, coincident with the onset of the Northern Hemisphere glaciations, and consequently forming the present desert regime. [Copyright &y& Elsevier]

River terrace sediments are archives of past fluvial processes and they may also reflect a wide range of additional environmental processes. Detailed studies of river terrace sediments are important for understanding the role of tectonics, climate and extreme geomorphological events in fluvial evolution. Here, we present a sedimentary reconstruction using the combination of field description, magnetic measurements and optically stimulated luminescence and AMS 14 C dating of the Maoxian (MX) section in the third terrace of the Min river, in the eastern margin of the Tibetan Plateau. The section is mainly composed of clastic deposits and spans the interval from the last glacial to late Holocene. Apart from the silt at the bottom and the gravel layer in the middle, it is difficult to determine whether other clastic deposits were exposed sub-aerially. Multiple magnetic proxies indicate that the MX section contains three layers of pedogenic production of fine-grained magnetite/maghemite, which correspond to paleosol layers. The paleosol layers indicate the occurrence of at least three intervals of exposure to the atmosphere. The three paleosol layers were likely caused by dam-outburst events. The results demonstrate that rock magnetic methods are a useful approach for identifying paleosol layers in fluvial sediments. [ABSTRACT FROM AUTHOR]

Abstract: Geological studies indicate that several Tertiary fluvial–lacustrine basins existed in northwestern China. Progressive uplift of the Tibetan Plateau forced these Tertiary basins to dry, and eventually became accumulation areas for aeolian sediments. Continuous sedimentary sequences consisting of alluvial–fluvial sediments and aeolian Red Clay occurred in the Lanzhou area. We used palaeomagnetic and palaeoenvironmental techniques to investigate a late Tertiary section that has a Quaternary loess cover. Our results indicate that the area was a low altitude basin with a fluvial–lacustrine environment before ~7.2Ma. Starting from ~7.2Ma, the basin became a dry land and was exposed to aeolian accumulation. The presences of unconformities and sedimentary facies changes suggest that strong tectonic activity occurred during the interval of 3.5–1.8Ma, which forced the Lanzhou Tertiary Basin to break up and became elevated to its present altitude. Gradual variations in sediment colour, grain-size and magnetic susceptibility imply that the Lanzhou area experienced progressive cooling and drying in the Late Cenozoic due to local tectonic uplift and global cooling. [Copyright &y& Elsevier]