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Crust–mantle interaction induced by continental subduction occurs through metasomatic reaction of continental crust-derived materials with mantle wedge peridotite in continental subduction channels. Mantle-derived igneous rocks above continental subduction zones can provide insights into the nature of crust–mantle interaction and the types of metasomatism. The Laixi region is located on the southeastern margin of the North China Craton adjacent to the Sulu orogen. Here, we present K–Ar dating, whole-rock major and trace elements, Sr–Nd–Pb isotopes, and olivine and clinopyroxene major and trace elements of the Laixi basalt to investigate the nature of metasomatism at the crust–mantle interface. These basalts exhibit geochemical inheritance of island arc basalt (IAB)-like trace-element patterns, moderately enriched Sr–Nd isotopic compositions, and variable Pb isotopic compositions from upper-crustal materials of the subducted South China Block. The olivine and clinopyroxene contents of the Laixi basalts indicate a mixed source composed of ~ 51% pyroxenite and ~ 49% peridotite which is the result of carbonate metasomatism. On the basis of the typical differences in MgO, CaO and Al2O3 contents between the Laixi basaltic magmas and experimental melts, the metasomatic agents are identified as carbonated eclogite-derived melts. These features of the IAB-like basalts suggest metasomatic reaction of mantle-wedge peridotite with carbonated silicate melt derived from the subducted upper crust in the continental subduction channel, with olivine being consumed to generate ultramafic metasomatites enriched in pyroxene. [ABSTRACT FROM AUTHOR]

Siraitia grosvenorii (LHG) is widely used as a medicinal and edible material around the world. The objective of this study was to develop an effective method for the authentication of the geographical origin of LHG in its main producing area Guangxi, China, which is identified as Chinese Protected Designation of Origin product, against other producing regions in China. The content of 14 elements (K, Na, Ca, P, Mg, Al, B, Ba, Cu, Fe, Mn, Ni, Zn, and Sr) of 114 LHG samples was determined by inductively coupled plasma optical emission spectrometry. Multivariate analysis was then performed to classify the geographical origin of LHG samples. The contents of multielement display an obvious trend of clustering according to the geographical origin of LHG samples based on radar plot and principal component analysis. Finally, three supervised statistical techniques, including linear discriminant analysis (LDA), k-nearest neighbours (k-NN), and support vector machine (SVM), were applied to develop classification models. Finally, 40 unknown LHG samples were used to evaluate the predictive ability of model and discrimination rate of 100%, 97.5% and 100% were obtained for LDA, k-NN, and SVM, respectively. This study indicated that it is feasible to attribute unknown LHG samples to its geographical origin based on its multielement content coupled with chemometric techniques. [ABSTRACT FROM AUTHOR]

As an important pilot target for shale gas exploration and development in China, the Longmaxi Formation shale in the Dianqianbei Area is characterized by high content of nitrogen, which severely increases exploration risk. Accordingly, this study explores the genesis of shale gas reservoir and the mechanism of nitrogen enrichment through investigating shale gas compositions, isotope features, and geochemical characteristics of associated gases. The high-nitrogen shale gas reservoir in the Longmaxi Formation is demonstrated to be a typical dry gas reservoir. Specifically, the alkane carbon isotope reversal is ascribed to the secondary cracking of crude oil and the Rayleigh fractionation induced by the basalt mantle plume. Such a thermogenic oil-type gas reservoir is composed of both oil-cracking gas and kerogen-cracking gas. The normally high nitrogen content (18.05%–40.92%) is attributed to organic matter cracking and thermal ammoniation in the high-maturity stage. Specifically, the high heat flow effect of the Emeishan mantle plume exacerbates the thermal cracking of organic matter in the Longmaxi Formation shale, accompanied by nitrogen generation. In comparison, the abnormally high nitrogen content (86.79%–98.54%) is ascribed to the communication between the atmosphere and deep underground fluids by deep faults, which results in hydrocarbon loss and nitrogen intrusion, acting as the key factor for deconstruction of the primary shale gas reservoir. Results of this study not only enrich research on genetic mechanism of high-maturity N2 shale gas reservoirs, but also provide theoretical guidance for subsequent gas reservoir resource evaluation and well-drilling deployment in this area. [ABSTRACT FROM AUTHOR]

The hominin record from southern Asia for the early Late Pleistocene epoch is scarce. Well-dated and well-preserved fossils older than ∼45,000 years that can be unequivocally attributed to Homo sapiens are lacking. Here we present evidence from the newly excavated Fuyan Cave in Daoxian (southern China). This site has provided 47 human teeth dated to more than 80,000 years old, and with an inferred maximum age of 120,000 years. The morphological and metric assessment of this sample supports its unequivocal assignment to H. sapiens. The Daoxian sample is more derived than any other anatomically modern humans, resembling middle-to-late Late Pleistocene specimens and even contemporary humans. Our study shows that fully modern morphologies were present in southern China 30,000-70,000 years earlier than in the Levant and Europe. Our data fill a chronological and geographical gap that is relevant for understanding when H. sapiens first appeared in southern Asia. The Daoxian teeth also support the hypothesis that during the same period, southern China was inhabited by more derived populations than central and northern China. This evidence is important for the study of dispersal routes of modern humans. Finally, our results are relevant to exploring the reasons for the relatively late entry of H. sapiens into Europe. Some studies have investigated how the competition with H. sapiens may have caused Neanderthals' extinction (see ref. 8 and references therein). Notably, although fully modern humans were already present in southern China at least as early as ∼80,000 years ago, there is no evidence that they entered Europe before ∼45,000 years ago. This could indicate that H. neanderthalensis was indeed an additional ecological barrier for modern humans, who could only enter Europe when the demise of Neanderthals had already started. [ABSTRACT FROM AUTHOR]

Estrogen receptor alpha (ER-α) plays an important role in mediating estrogen signaling. Studies in Caucasian populations have shown that it is involved in endocrine-related diseases such as osteoporosis and obesity. In the present study, we first used a quantitative transmission disequilibrium test (QTDT) to examine the relationship between this gene and both the osteoporosis-related phenotype bone mineral density (BMD), and the obesity-related phenotype body mass index (BMI), in 384 Chinese nuclear families. We genotyped a dinucleotide repeat marker (TA) n, and a long-range haplotype was reconstructed using this marker and two other restriction fragment length polymorphism (RFLP) markers at PvuII and XbaI loci. Although we found significant total association [allele (TA)21 with hip BMD ( P=0.001), and haplotype Px(TA)21 with spine ( P=0.0007) and hip ( P=0.0006) BMD], the more reliable within-family associations were not significant between these phenotype pairs. No linkage signal was obtained for either spine BMD or hip BMD. We found no association or linkage between any of the three studied polymorphisms and the long-range haplotypes of the ER-α gene and BMI. Our study does not support an association of the ER-α gene with BMD and BMI in the Chinese population. [ABSTRACT FROM AUTHOR]