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El Niño-Southern Oscillation (ENSO) is the most significant global ocean–atmosphere coupled signal in the tropical Pacific Ocean, and it can affect the stratosphere. However, the ENSO-related dynamical processes that influence the ozone valley during summer are still not well understood and are under-investigated. In this study, we used the ERA5 and MERRA-2 reanalysis data from 1979 to 2021 combined with numerical simulations to analyze the mechanisms through which ENSO affects the ozone valley over the Tibetan Plateau in the upper troposphere and the lower stratosphere (UTLS) in summer. The results showed that the two cores of the ozone valley in UTLS were more evident in the summer following La Niña than in the summer following El Niño. At low latitudes, negative O3 anomalies in UTLS were observed in the summer following El Niño and positive O3 anomalies were observed in the summer following La Niña. At middle latitudes, negative O3 anomalies in UTLS were found near 60°E in the summer following El Niño, while negative anomalies were found at 40°E and 120°E in the summer following La Niña. The analysis of the flow and vorticity fields suggested that the field anomalies can cause vertical motion, which in turn leads to the mixing of different ozone concentrations and affects the ozone valley in UTLS over the Tibetan Plateau. In particular, the warming of the Indian Ocean sea-surface temperature (SST) in the summer following El Niño enhances the South Asian High (SAH) through two-stage thermal adaptation, leading to ozone anomalies at low latitudes in the ozone-valley region. These conclusions were verified by a simulation using the WACCM4 model, the results of which were consistent with the original observations. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Subashi ophiolite in West Kunlun Orogenic Belt was formed at ca. 455–446 Ma. • Geochemical features indicate the Subashi ophiolite formed in a MOR setting. • Mazha-Kangxiwa mélange zone with Subashi ophiolite marks a Proto-Tethys suture. The West Kunlun Orogenic Belt (W-KOB) in the northwestern Tibetan Plateau retains critical information about the tectonic evolution of the Proto- and Paleo-Tethys during the Early Paleozoic to Mesozoic. Although a trench-arc-back arc basin model was used to address the tectonic evolution of Proto-Tethys, records about the evolution of this ocean basin remain ambiguous, particularly no studies about ages and tectonic affinities of ophiolites in the W-KOB are available. In this paper, we present new results on whole-rock elemental and Sr-Nd isotopic composition of basalts, and U-Pb zircon ages of gabbro, diabase and basalt from the Subashi ophiolite. The basalts are characterized by low REE concentrations, depleted LREEs in the chondrite normalized REE patterns, and unfractionated HFSEs in the primitive mantle normalized trace element spider diagrams, resembling normal mid-ocean ridge basalts. They have constant 87Sr/86Sr(i) values of 0.70472–0.70590 and positive ε Nd values of +7.5 to +7.9. Accordingly, it can be concluded that the Subashi ophiolite was derived from a depleted spinel lherzolite mantle source in a mid-ocean ridge setting. Zircon grains separated from basalt, diabase and gabbro have 206Pb/238U ages of 455 ± 4 Ma, 451 ± 6 Ma, and 446 ± 6 Ma, respectively, which are taken to be the crystallization ages of these rocks. Together with previously published data, our new data propose that the Mazha-Kangxiwa-Subashi ophiolitic mélange zone marks the existence of the Proto-Tethys ocean basin during the Early Paleozoic. [ABSTRACT FROM AUTHOR]

The occurrence of gas hydrate deposits in the Qinghai-Tibet plateau permafrost (QTPP) were confirmed during the Scientific Drilling Project of Gas Hydrate in Qilian Mountain permafrost (QMP) in 2008-2009. A total of four test wells were completed, and gas hydrate samples were obtained from the drilling wells of DK-1, DK-2, and DK-3. The objective of this study is the analysis of gas production potential from gas hydrate-bearing zone of DK-2 using dual horizontal wells based on its geological properties at this site. In this paper, production strategies of permafrost hydrate deposits with the novel Heat-Assisted Antigravity Drainage (HAAD) method are investigated numerically. Gas production is induced in a two-well system and its influence factors are evaluated. When suitable heat injection rate and depressurization driving force are applied to the lower well and the upper well, respectively, favorable gas-to-water ratio and energy ratio can be obtained during the whole HAAD process. However, the absolute gas production rate may not be economically attractive for the production method we have employed. The sensitivity analysis indicates that the hydrate deposits with higher intrinsic permeability and larger rock porosity will show better perspective for hydrate exploitation. [ABSTRACT FROM AUTHOR]