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Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua daily land surface temperature (LST) products are important data sets for global warming monitoring. To reveal the consistency and differences between MODIS Terra and Aqua daily LST products for monitoring LST trends, this study used these two products to extract the mean annual surface temperature (MAST) of the Tibetan Plateau from 2003 to 2020. Then, nine MAST combinations were constructed for daytime, nighttime, and daily average conditions separately with Terra and Aqua MAST series, including Terra only, Aqua only, and the integrated one. Finally, the Mann‐Kendall trend test was applied to these series and obtained the spatiotemporal variability. The results indicated that there was high spatial consistency of the multi‐year averaged MAST of different combinations at daytime/nighttime/daily average scales. Meanwhile, there are quite similar temporal trends in terms of spatial distribution and change rate. The MAST changes are dominated by warming trends, and the areas and change rates of the significant changing pixels at different elevations, vegetation cover ranges, and land cover types presented similar distribution patterns. Although there are some discrepancies in the detailed location for pixels with significant trends among different combinations, the proportion of the pixels with the same trends of daytime/nighttime/daily‐average groups is as high as 68.88%, 66.75%, and 71.76%, respectively. These findings reveal that different MODIS LST products have similar performance in monitoring LST trends, indicating that the detection can well reflect the variation of surface thermal environment regardless of which MODIS LST product is used. Key Points: Different land surface temperature (LST) combinations were generated with Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua daily daytime and nighttime LST productsThe daytime, nighttime, and daily averaged mean annual surface temperature from different combinations show similar spatial distributions over the Tibetan PlateauThe detection well reflects the variation of surface thermal environment regardless of which MODIS LST product is used [ABSTRACT FROM AUTHOR]

We present new geochronological, mineralogical, geochemical, and isotopic data for recently recognized lamprophyre dikes in the East Kunlun orogenic belt of NW China. Based on euhedral amphibole phenocrysts and fine-grained, plagioclase-bearing groundmass with accessory magnetite, apatite, and titanite, these dikes are classified as spessartites. Plagioclase in these rocks is Ca-rich with An ranging from 45 to 82. Most of the amphibole phenocrysts are magnesiohastingsite or ferropargasite, with systematic ‘‘normal’ zoning in which Al2O3, CaO, and Mg# decrease from core to rim. The dikes have moderate Mg# (43–49) and high Al2O3(17.5–18.0 wt.%), FeOtotal(7.4–8.4 wt.%), and CaO (5.9–7.4 wt.%). Based on low total alkalis (Na2O + K2O = 4.2%–5.0 wt.%), most samples plot in the low-K, calc-alkaline field. They are enriched in large-ion lithophile elements (e.g. K, Rb, Sr, and Ba) and light rare-earth elements, but are depleted in high-field-strength elements (e.g. Ta, Nb, P, and Ti), and have enriched Sr-Nd-Hf isotopic compositions ((87Sr/86Sr)i = 0.70883–0.71045, εNd(t) = –5.51–5.72, εHf(t) = –4.42–0.38). Zircon U–Pb geochronology indicates that the dikes were emplaced at 253 ± 2.5 Ma and are unrelated to their granite host, which has an age of 443 ± 1.7 Ma. The geochemical and isotopic data suggest derivation from an enriched lithospheric mantle source that had been metasomatized by subduction-related fluids. Low degrees of partial melting of a phlogopite-bearing, spinel peridotite, followed by fractional crystallization of olivine, amphibole, and Ti-bearing minerals, can account for the observed geochemical features of the dikes. Trace element geochemistry and regional geology suggest that the East Kunlun lamprophryes formed in a subduction-related setting. [ABSTRACT FROM AUTHOR]

Voluminous granodioritic magmatism is recorded in the East Kunlun, Northern Qinghai-Tibet Plateau. Here we present mineralogical, petrological, geochemical and Sr-Nd-Hf isotopic data and zircon U-Pb ages for the Naomuhun pluton and its numerous mafic microgranular enclaves (MMEs). Whole-rock geochemical data and regional geological studies indicate that this pluton consists of subduction-related high-K calc-alkaline metaluminous, I-type granodiorite. The MMEs have plagioclase xenocrysts and disequilibrium textures, such as oscillatory zoning and resorbed rims, indicating magma mixing. Compositions of plagioclase (An-An), amphibole (Mg# = 0.62 ~ 0.68), and biotite (Mg# = 0.52-0.56) of MMEs are similar to or very slightly different from equivalent minerals in the host granodiorites, suggesting nearly complete equilibration between the mafic-and felsic magmas. The zircon U-Pb age of the MMEs (263 ± 2 Ma) is identical, within analytical error, to that of the host granodiorites (261 ± 2 Ma). The MMEs have ε(t) values of −6.83 to −3.15 (average = −4.68), whereas those of the granodiorites range from −9.00 to −3.20 (average −5.63), which is identical within analytical uncertainty. Combined with relatively homogeneous Sr-Nd isotopic compositions, we suggest the MMEs were derived from magma mixing, and their source is similar to an enriched mantle composition. The granodiorites have T(Hf) model ages ranging from 1.49 to 1.86 Ga, consistent with the Nd model ages (T), implying that the host magma was derived from Paleo- or Meso-proterozoic rocks, probably the Xiaomiao Group, which forms the basement of East Kunlun. We propose a model for magma formation and magma mixing in a subduction zone environment, in which subduction of an oceanic slab at ca. 260 Ma led to fluid metasomatism, inducing partial melting of an enriched lithospheric mantle to form the voluminous mafic magma. The mafic magma underplated the overlying lower crust, resulting in its partial melting to form felsic magma. The mafic magma then mixed with the felsic magma at lower crustal levels to form the MMEs by convective motion, or forceful injection into the host felsic magma. The MMEs and their host magma were then emplaced at a depth of ca. 12 km, where they crystallized at a temperature of ca. 700-770°C. [ABSTRACT FROM AUTHOR]

Although numerous Paleo-Tethyan ophiolites with mid-oceanic ridge basalts (MORB) and/or oceanic-island basalt (OIB) affinities have been reported in the central Tibetan Plateau (CTP), the origin and tectonic nature of these ophiolites are not well understood. The petrogenesis, mantle sources and geodynamic setting of the mafic rocks from these ophiolites are unclear, which is the main reason for this uncertainty. In this paper, we present new geochronological, mineralogical and Sr-Nd isotopic data for the Chayong and Xiewu mafic complexes in the western Garzê-Litang suture zone (GLS), a typical Paleo-Tethyan suture crossing the CTP. Zircon LA-ICP-MS U–Pb ages of 234 ± 3 Ma and 236 ± 2 Ma can be interpreted as formation times of the Chayong and Xiewu mafic complexes, respectively. The basalts and gabbros of the Chayong complex exhibit enriched MORB (E-MORB) compositional affinities except for a weak depletion of Nb, Ta and Ti relative to the primitive mantle, whereas the basalts and gabbros of the Xiewu complex display distinct E-MORB and OIB affinities. The geochemical features suggest a probable fractionation of olivine ± clinopyroxene ± plagioclase as well as insignificant crustal contamination. The geochemical and Sr-Nd isotopic data reveal that the Chayong mafic rocks may have been derived from depleted MORB-type mantle metasomatized by crustal components and Xiewu mafic rocks from enriched lithospheric mantle metasomatized by OIB-like components. The ratios of Zn/Fe t , La/Yb and Sm/Yb indicate that these mafic melts were produced by the partial melting of garnet + minor spinel-bearing peridotite or spinel ± minor garnet-bearing peridotite. We propose that back-arc basin spreading associated with OIB/seamount recycling had occurred in the western GLS at least since the Middle Triassic times, and the decompression melting of the depleted MORB-type asthenosphere mantle and partial melting of sub-continental lithosphere were metasomatized by plume-related melts, such as OIB s, which led to the generation of the Chayong and Xiewu mafic melts. [ABSTRACT FROM AUTHOR]