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Reports a multichronometric evidence for an in situ origin of the ultrahigh-pressure metamorphic terrane of Dabieshan, China. Indication of the U-Pb zircon data on gneisses; Analysis of phengite from several gneisses; Correlation between the peak and the retrograde evolution.

Abstract: In the Kharta area, east of Mount Everest, the Greater Himalayan Crystallines are significantly richer in mafic rocks than the surrounding areas, Sikkim–West Bhutan and Makalu–Cho Oyu. These rocks are lenses with a complex metamorphic history. The mafic lenses of Shao La, in the Greater Himalayan Sequence south of Kharta, are here considerated as dismembered dykes apparently escaped the Himalayan high-temperature metamorphism and only record a low-grade metamorphic event. They are calc-alkaline medium-K basalts to basaltic andesites, consisting of plagioclase (core 62% An and rim 55% An), augite (Wo43–47En3636–37Fs16–20), hypersthene (Wo1.6–3.3En50–52Fs46–48), and minor brown hornblende, biotite and ilmenite. They show strong enrichment in low ionic potential elements relative to high-field-strength elements, and only minor Ce and P enrichment with respect to MORB. Combined Sr–Nd systematics suggest contamination of a basic magma from a subcontinental mantle source with a small amount of crust (about 4 vol.%). This in turn indicates that the Shao La basalts and basaltic andesites have the geochemical fingerprint of a supra-subduction zone magma. U–Pb dating of zircon from one sample yielded an age of 457±6Ma for the crystallisation of the Shao La basic rocks, assigning them to the Cambro-Ordovician Bhimphedian orogenic event. The age and geochemical characteristics of the Shao La rocks are similar to those of the basic rocks of the Cambro-Ordovician Mandi pluton further west. This suggests the existence of an extensive supra-subduction zone magmatism along the Indian margin of Gondwana. Like the bimodal granite-gabbro magmatism in the Mandi-Kaplas area, the Shao La basic rocks are contemporaneous with the emplacement of granitic plutons in the Everest-Kharta area. This acid plutonism is interpreted as crustal melt triggered by the upwelling of metasomatised mantle in a back-arc setting. The age of basic and acidic plutonism in the Everest-Kharta area is evidence that the Bhimphedian Orogeny was still active as late as the Late Ordovician [Copyright &y& Elsevier]

Multiple sulfur (δ 34 S sulfate , Δ 33 S sulfate , & Δ 36 S sulfate ), nitrogen and oxygen (δ 15 N nitrate & δ 18 O nitrate ) and strontium ( 87 Sr/ 86 Sr) isotope compositions of precipitation collected from Seoul, South Korea were analyzed to study the sources, transportation and deposition of air pollutants in East Asia. The δ 34 S sulfate values (from 1.9 to 14.6‰ with a median of 4.7‰) and the δ 15 N nitrate values (from -2.0 to 13.3‰ with a median of 1.0‰) suggest that fossil fuel use (emission from coal combustion and vehicle exhaust) is a predominant source for sulfur and nitrogen, but other natural sources including biogenic contributions of DMS also add to their total budget. The seasonal variations are observed in δ 34 S sulfate and δ 15 N nitrate values (both higher in winter season), which is likely to result from the increase of coal use for domestic heating in China. The δ 18 O nitrate values also varied seasonally depending on the NO x oxidation pathway, being about 20‰ higher in winter than in summer season. The Δ 33 S sulfate and Δ 36 S sulfate values are not anomalous, showing the absence of MIF signals in precipitation of Seoul. The 87 Sr/ 86 Sr ratio of the precipitation samples range from 0.70988 to 0.71487 with a median of 0.71073, indicating the influence of at least three end-member (silicate dust, carbonate dust and anthropogenic emission). Ionic ratios such as (K + +NH 4 + )/(Ca 2+ +Mg 2+ ) and Cl - /Na + suggest the overwhelming effect of anthropogenic input rather than carbonate dust on the end-member with lower 87 Sr/ 86 Sr ratios., (Copyright © 2021 Elsevier Ltd. All rights reserved.)