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In this paper, we examine the Early to Middle Holocene evolution of a prominent group of ground-water fed lakes in the southeastern hinterland of the Badain Jaran Desert (BJD) of northwest China. Specifically, we describe a sediment profile record from the Taoerlegetu (TR) palaeolake basin using multiple proxies of total organic carbon (TOC), total nitrogen (TN), C/N ratio, δ13C org , grain size and mineral composition based on a well-dated trench profile. As C/N values suggest that sedimentary organic matter mainly originated from aquatic plants, δ13Corg values can be used as a qualitative proxy for water level because aquatic plants in different biotopes (water depth) have different δ13C values. Our results show that from 10.9 to 9.1 cal kyr B.P., water level rose slowly, and aquatic macrophytes occupied the lake basin. From 9.1 to 5.5 cal kyr B.P., water level reached an even higher level and phytoplankton replaced macrophytes as the major contributor to organic matter. The humid episode of the lakes in the hinterland of the BJD in the early Holocene might be related to the increased groundwater supply from the northeast region of the Tibet Plateau. These findings are consistent with earlier studies of lacustrine and peat sediments found in periphery of the modern lake group, which indicate that their geographic extent may have been larger in the past. A relative drought period recorded in the studied succession from 8.5 to 8.0 cal kyr B.P. marks an interval of reduced ground-water transport from the Tibet Plateau. This interval probably corresponds to the "8.2 ka cold event" and provides evidence that this widespread climate episode influenced groundwater processes across inland Asia. • The δ13C org value could be used as a qualitative indicator for the change of water level. • Lakes in the hinterland of the Badain Jaran Desert shows different evolution progress with these in the edge. • The main water source of lakes in the hinterland of the BJD in the Early Holocene comes from the Tibet Plateau. [ABSTRACT FROM AUTHOR]

The Silurian conodont biozonation has been well established in many areas of the world, but not yet in China. The Nyalam region of southern Xizang (Tibet) is one of the best locations for studying Silurian conodonts in China. In this paper, we establish five conodont biozonal units from the Pulu Formation: the Ozarkodina sagitta sagitta Biozone, the Kockelella crassa Biozone, the Kockelella variabilis variabilis – Ancoradella ploeckensis Zonal Group, the Polygnathoides siluricus Biozone, and the " Ozarkodina " eosteinhornensis s.l. interval Biozone. We assign the Pulu Formation to the Llandovery (upper Telychian) to Pridoli stages based on the conodonts as well as the graptolites from underlying strata. The Silurian conodont species in the Nyalam region are widely distributed in the strata from the Laurussia and Gondwana, which indicates the cosmopolitan characteristic of the conodont fauna from the Wenlock to Pridoli epochs was caused by the circulation of ocean currents. • Five conodont biozonal units from Wenlock to Pridoli were identified in the Nyalam region. • Pulu Formation in the Nyalam region is Telychian to Pridoli in age. • Silurian conodont fauna in the Nyalam region have a cosmopolitan characteristic. [ABSTRACT FROM AUTHOR]