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Compositional changes of successively emplaced magmatites can be used to infer changes in their petrogenetic evolution and geodynamic setting. The central-northern Lhasa terrane hosts extensive Late Cretaceous magmatism, however, the mechanism that triggered the magmatism and its relationship to the directly preceding Late Cretaceous tectonic transition in the central Tibetan Plateau is still unresolved. Therefore, we conducted a detailed petrological, geochronological, geochemical, and isotopic study on recently identified Late Cretaceous doleritic and granodioritic rocks in the Xiongmei area, northern Lhasa subterrane. The potassic (K2O/Na2O ratios >1) dolerites (ca. 80 Ma) display a post-collisional basaltic shoshonitic signature with uniform moderately enriched whole-rock Sr–Nd and zircon–Hf isotopic compositions ((87Sr/86Sr)t = 0.7070 to 0.7095, whole-rock εNd(t) = – 2.4 to – 1.3, and zircon εHf(t) = – 5.9 to +1.9), suggesting that they evolved from a similar parental magma and were likely derived by partial melting of an enriched lithospheric mantle metasomatized by hydrous fluids. The granodiorites are geochemically divided into medium-K and high-K calc-alkaline rocks. The medium-K samples (ca. 80 Ma) are generally characterized by low K2O/Na2O ratios <1, whereas the high-K samples (78–76 Ma) display high K2O/Na2O ratios >1. The medium-K samples have positive zircon εHf(t) values from +4.8 to +6.5 and uniform whole-rock ɛNd(t) values from – 2.4 to – 1.3, which significantly differ from those of the high-K samples that have negative to positive zircon εHf(t) values from – 1.9 to +2.8 and negative whole-rock ɛNd(t) values from – 8.4 to – 5.1. The medium-K samples are characterized by high Sr contents and Sr/Y ratios, coupled with low Y and HREE contents, similar to adakitic compositions, and were interpreted to have been derived from deep partial melting of the foundering juvenile garnet-bearing mafic lower crust at relatively low temperatures. Compared to the medium-K samples, the high-K samples have lower Sr/Y and (La/Yb)N ratios, coupled with flat HREE patterns and distinct negative Eu, Sr and Ti anomalies and are most likely derived from shallower partial melting of the K-rich juvenile lower crust at relatively high temperatures. Considering the occurrence of variable magmatism in the central-northern Lhasa subterrane during the Late Cretaceous, the change in magma composition and lower crustal melting conditions (cold-deep vs. hot-shallow) suggest that the lithospheric mantle keel was partially detached by small-scale mantle convection in response to the low-angle Neo-Tethys-associated subduction between 85 and 70 Ma. [ABSTRACT FROM AUTHOR]

The 2021 M w 7.4 Maduo earthquake occurred on the left-lateral Kunlun Pass-Jiangcuo fault (KPJF) located within the Bayan Har block, Tibetan Plateau, caused an ∼165-km-long surface rupture and widespread ground deformation. This earthquake was well recorded by SAR images and our near-field GPS network during the coseismic and postseismic periods, providing a rare opportunity to shed light on the seismic and aseismic slip behaviors on the slow-slipping causative fault. Here, we constrain the coseismic slip distribution of the 2021 Maduo earthquake by the joint use of InSAR and near-field GPS observations. Then, time-dependent afterslip evolution is inverted from cGPS and InSAR time series in the first ∼160 days after the mainshock. The results show that the mainshock involves five asperities with a maximum slip of 4.79 m, including an E -W trending main fault and a secondary fault locates on the eastern end of the main fault. The significant energy released near Changmahe Township could be partialy explained by the fact that the seismogenic fault here cut through the pre-existing NW-SE trending faults. Afterslip played a dominant role in the early postseismic deformation, which has released seismic moment equivalent to an M w 6.78 earthquake, 10.3% of the coseismic moment. The seismic and aseismic slip distributions have complementary patterns in spatial, except for the overlaps on the Changmahe segment, suggesting the heterogeneity of frictional property on the fault plane. The rupture of the Maduo earthquake is located in the stress shadow induced by historical earthquakes, indicating the high accumulated stress on the KPJF. The stress level, as well as the potential seismic hazard on the ∼300-km-long seismic gap between the 2001 Kokoxili earthquake and the 2021 Maduo earthquake, is further raised by the historical events. • The Co- and postseismic deformations of the 2021 Maduo earthquake are recorded by SAR images and our near-field GPS network. • The mainshock involves five asperities with a maximum slip of 4.79 m. • Afterslip has released seismic moment equivalent to an M w 6.78 earthquake. • Overlaps between the seismic and aseismic slips are found on the Changmahe segment. • The Maduo earthquake is located in the stress shadow induced by historical events. [ABSTRACT FROM AUTHOR]

This paper presents an in-depth analysis of urbanization dynamics on the Tibetan Plateau through the lens of Special Economic Zones (SEZs), addressing a research gap in the understanding of urbanism in highland and global south contexts. Given the current surge of assembly-based thinking within urban scholarship, we employ an assemblage framework to comprehend the heterogeneous constitution of urbanization, integrating human and non-human components, as well as socio-material, political, and spatial governances. Through a meticulous examination of three comprehensive case studies from the Tibetan Plateau SEZs, including a state-led new town, a renewable energy-driven industrial zone, and an industrial enclave, we delineate the diverse forms of plateau urbanism. Our findings underscore the imperative for contextually tailored urban development strategies that consider the distinctive geographical, ecological, and socio-political conditions of the Tibetan Plateau. It emphasizes the need for adaptive governance and planning that can address infrastructure deficiencies, environmental constraints, and the integration of local communities. Furthermore, we also call for further exploration of urbanisms in other highland regions, advocating for a more longitudinal, crosswise and nuanced understanding of urbanization processes in various global contexts. • Plateau urbanism as an assemblage of diverse plateau material and immaterial urbanization forces. • We aim to explore the interactions of various actors, diverse dynamics of spatial logics, and multifaceted spatial modes that underlie the ongoing territorial transformation of the plateau cities. • We pioneeringly applies assemblage thinking to conceptualize and empirically investigate plateau urbanism on China's Tibetan Plateau. • The study presents a comprehensive examination of three distinct Special Economic Zones (SEZs) on the Tibetan Plateau. • The paper advocates for a more inclusive and nuanced approach to urbanization processes in the lens of assemblage thinking. [ABSTRACT FROM AUTHOR]

The influence of the Indian summer monsoon (ISM) and mid-latitude westerlies on the central Tibetan Plateau (TP) during the Holocene, particularly during the mid-Holocene, is still unclear, limiting our understanding of past climate change in this region. Cuona Lake, located on the central TP, is a transitional zone of atmospheric circulation that is well situated for investigations on the interplay between the ISM and mid-latitude westerlies. In this study, multiple proxies of lacustrine sediments from Cuona Lake were measured, including total organic carbon (TOC), total nitrogen (TN), δ13C org , n -alkanes, and their hydrogen isotopes, to reconstruct the evolution of climate on the central TP over the past 13 cal kyr BP. Decreased TOC/TN ratios, dominant short-chain n -alkanes/alkanoic acid C 15/16/17 , and lower values of n -alkane indicator ratios (carbon preference index and average chain length) throughout the investigated period suggest that the organic matter of the lake essentially originated from aquatic algae, and was weakly affected by terrestrial input. The historic variations in the δD, TOC, and δ13C org values revealed cold-wet conditions during 12.4–11.4 cal kyr BP, warm-wettest environments during the early Holocene (from 11.4 to 8.2 cal kyr BP), cool-wet conditions in the mid-late Holocene (from 5 to 3 cal kyr BP), and warm-dry conditions since 3 cal kyr BP. The reconstructed climatic variability in the Cuona area agrees well with previous indexes in south-central TP, indicating that the climatic pattern of the studied area is basically controlled by the monsoonal circulation from the late part of the last deglaciation to the early Holocene, with the ISM reaching the north-central TP at ∼11 cal kyr BP. During the mid-late Holocene, the humid conditions coincided with an enhanced influence of westerlies, providing strong evidence for the contribution of westerlies-delivered moisture to the central TP. Based on a comparison of paleoclimate records, the Cuona region displays a transitional phase between monsoon circulation and westerly jets during the Holocene. • High-resolution hydroclimate records from Cuona in the central TP since 13 kyrs. • Four stages with distinct climate trend and millennial-scale change were identified. • Contributions of Westerly air masses lead to wet conditions in the transition zone. • Both Indian summer monsoon and Westerlies are involved over the past 13 cal kyr BP. [ABSTRACT FROM AUTHOR]

Koucha Lake, located in Qinghai Province, north-eastern Tibetan Plateau (NETP) at an elevation of 4530 m a.s.l. Occupies an ideal position to investigate the seasonal hydroclimatic variations and related surface processes during the Holocene. We re-investigated the lake and analysed a new sediment core from the deepest part of the lake. Grain size measurements and related endmember modelling analyses (EMMA) in combination with ostracod associations together with geochemical parameters and mineral compositions from core sediments were used as relevant proxies for hydro-climatic reconstruction.A comparison of δ18O/δD from various waters on the NETP indicates a clear depleted isotopic signature of non-monsoon moisture supply in comparison to summer rainfalls, highlighting the summer evaporation for δ18O enrichment, as a reference for interpreting δ18O values from lake sediments for various situations of hydrological balance. Based on the individual core chronology the multi-proxy data indicate a very low sedimentation rate over the entire period in accordance with the catchment topography and the absence of well-developed and constant river systems, limiting the flux of sediment supply to the lake. Thus, Koucha Lake remains almost a closed system since the Lateglacial, except for the early mid-Holocene part of the sequence. The coarser particle components and their representative endmembers for spring flood and permafrost thaw between 11.9 and 10.1 cal Ka BP and from 4.5 to ca. 1.0 cal Ka BP point to lower lake levels, influenced by long winter duration with dry summer interruptions, and lighter oxygen isotopes were preserved at low evaporations. Fine-grained sediments supplied by permafrost thaw associated with activating summer surface erosion led to lake level rise between 10.1 and 4.5 cal Ka BP and during the last 1000 years, with a maximum during 7.6–7.1 cal Ka BP. Their enriched δ18O values indicate extended summer duration and concomitant evaporation enhancement, albeit a positive hydrological balance. We suggest that the interannual latitudinal shifts of the intertropical convergence zone (ITCZ) and westerly Jet and attendant varying monsoon rain belt locations are responsible tracers for the variation of the hydrological budget of the lake and the variable spatio-temporal precipitation patterns in humid and (semi) arid regions in China. • Surface processes varied interannually and between cold and warm seasons during the Holocene. • Co-existence of long cold winter and dry summer extremes at high altitudes. • Synchronous/asynchronous patterns of heat and precipitation distribution between high/low altitudes in China. • These patterns correspond to the interannual latitudinal shifts of the ITCZ and the westerly jet. [ABSTRACT FROM AUTHOR]