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Mountain glaciers are one of the most sensitive indicators of climate change. Reconstructing past glacier extents provides valuable insights into the climate change for specific regions where instrumental records are not enough and even absent. In the paper we mapped the outlines for 691 Little Ice Age (LIA) glaciers in terms of prominent moraines beyond contemporary glaciers in the Tanggula Mountains, central Tibetan Plateau (TP). Based on these glacier outlines, we reconstructed the ice thicknesses and surfaces for the LIA glaciers in the region. Accordingly, we calculated the equilibrium-line altitudes (ELAs) for contemporary and LIA glaciers. By comparing the ELAs between the contemporary and LIA glaciers, we estimated the LIA summer temperature decreases in different subregions of the Tanggula Mountains. Since the LIA, the ELA have risen by 35.6 ± 18.8 m, 26.1 ± 17.6 m, and 63.1 ± 38.6 m in the respective western, central, and eastern subregions of the Tanggula Mountains. Assuming no change in precipitation, the LIA summer temperature would decrease by 0.22 ± 0.12 °C, 0.14 ± 0.09 °C, and 0.34 ± 0.21 °C in the three subregions, respectively. Moreover, glaciers in the western, central, and eastern subregions have lost 13.3%, 23.9%, and 42.8% of their area, 15.4%, 25.3%, and 39.6% of their length, and 20.8%, 39.0%, and 61.0% of their volume, respectively. By compiling the LIA ELA data from previous studies, we also estimated the LIA summer temperature changes for other regions of the TP. The LIA ELA and summer temperature changes relative to the present showed a decreasing trend from the edges towards the interior on the TP. • LIA glaciers and summer climate were reconstructed at the Tanggula Mountains. • LIA summers were 0.22 ± 0.12 °C, 0.14 ± 0.09 °C, and 0.34 ± 0.21 °C cooler than present in three subregions. • Summer temperature change had a decreasing trend from the edges towards the interior on the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

The uplift of the Tibetan Plateau has been widely associated with India-Asia continental collision during the Cenozoic. However, recent studies have proposed that a proto-Tibetan Plateau in central Tibet was elevated during the late Mesozoic. This paper improves that understanding by focusing on the Cretaceous terrestrial strata in the Gerze area of central Tibet. Our studies suggest that the Qushenla Formation in the Nare area contains alluvial fan conglomerate intercalated with rhyolitic ignimbrite and vesicular rhyolite. Zircon U Pb dating of rhyolitic ignimbrite (103.9 ± 1.4 Ma) and two granitoid boulders of conglomerate (106.0 ± 1.6 and 106.1 ± 1.5) indicate that the Qushenla Formation was deposited during the late Albian. The compositions of the Qushenla Formation conglomerate were dominated by hypabyssal intrusions on the southern Qiangtang terrane, which recorded a rapid uplift and denudation process in the late Albian, accompanied by intense volcanic eruptions. The second set of terrestrial strata is the Upper Cretaceous Jingzhushan Formation alluvial fan-braided river deposits, which can be divided into a lower conglomerate member (Member 1) and a upper sandstone member (Member 2). The large amount of bioclastic limestone fragments in the Member 1 show that they come from the Upper Cretaceous Langshan Formation in the central and northern Lhasa subterranes. While in the Member 2, abundant limestone debris, detrital zircon yielding Jurassic–Cretaceous ages with ε Hf (t) values between −18.6 and + 8.4, and occurrence of volcanic and ancient zircon grains indicate a volcanic-sedimentary source located in the central and northern Lhasa subterranes, with some input from the Bangong-Nujiang suture zone. This suggests that the central and northern Lhasa subterranes experienced rapid crustal uplift in the Late Cretaceous, thus ending the marine sedimentary environment since the Jurassic. Based on the temporal and spatial sedimentary characteristics of the Qushenla and Jingzhushan formations as well as the regional data, our integrated study suggests that the central plateau (Lhasa and southern Qiangtang terranes) experienced a complex uplift history during the Aptian-Turonian, with southwards stepwise growth in time and space. Furthermore, the uplift mechanism of the central plateau is complex, which was controlled by the diachronous closure of the Bangong-Nujiang Tethyan Ocean from east to west during the Early Cretaceous, and by the far-field forces associated with northwards subduction of the Neo-Tethys Ocean during the Late Cretaceous. [Display omitted] • There are two sets of Cretaceous terrestrial strata in the Gerze area. • Gerze area had a residual sea retreat southwards during Aptian-Turonian. • Central Tibet experienced a dual diachronic uplift of E–W and N S in Aptian-Cenomanian • We suggest that the early uplift process of central Tibet was phased. [ABSTRACT FROM AUTHOR]