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The Xinlu Sn‐polymetallic ore field is located in the western Nanling Polymetallic Belt in northeastern Guangxi, South China, where a number of typical skarn‐, hydrothermal vein‐type tin deposits have developed. There are two types of Sn deposits: skarn‐type and sulfide‐quartz vein‐type. The tin mineralizations mainly occur on the south side of the Guposhan granitic complex pluton and within its outer contact zone. To constrain the Sn mineralization age and further understand its genetic links to the Guposhan granitic complex, a series of geochronological works has been conducted at the Liuheao deposit of the ore field using high‐precision zircon SHRIMP U‐Pb, molybdenite Re‐Os, and muscovite Ar‐Ar dating methods. The results show that the biotite‐monzogranite, which is part of the Xinlu intrusive unit of the Guposhan complex pluton, has a SHRIMP U‐Pb zircon age of 161.0 ± 1.5 Ma. The skarn‐type ore has a 40Ar‐39Ar muscovite plateau age of 160 ± 2 Ma (same as its isochron age), and the sulfide‐quartz vein‐type ore yields an Re‐Os molybdenite isochron age of 154.4 ± 3.5 Ma. The magmatic‐hydrothermal geochronological sequence demonstrated that the hydrothermal mineralization took place immediately following the emplacement of the monzogranite, with the skarn metasomatic mineralization stage predating the sulfide mineralization stage. Geochronologically, we have compared this ore field with 26 typical Sn deposits distributed along the Nanling Polymetallic Belt, leading to the suggestion of the magmatic‐metallogenic processes in the Xinlu ore field (ca. 161–154 Ma) as a component of the Early Yanshanian large‐scale Sn‐polymetallic mineralization event (peaked at 160–150 Ma) in the Nanling Range of South China. Petrogenesis of Sn‐producing granite and Sn‐polymetallic mineralization were probably caused by crust–mantle interaction as a result of significant lithospheric extension and thinning in South China in the Late Jurassic. [ABSTRACT FROM AUTHOR]

Many colonies of macaques ( Macaca fascicularis and Macaca mulatta) are maintained in China, especially in Guangxi and Guizhou. A total of 803 fresh stool samples infected with Entamoeba were obtained from three big colonies of macaques located in southwest China. The samples were examined for the presence of five Entamoeba species using PCR. Entamoeba nuttalli, Entamoeba dispar, Entamoeba coli, and Entamoeba chattoni infections were detected, but Entamoeba histolytica infection was not. This study is the first to report on the prevalence of E. nuttalli in wild macaques from China. Eighteen E. nuttalli isolates and five E. dispar isolates were obtained by culturing the samples in Tanabe-Chiba medium. The serine-rich protein (SRP), ribosomal RNA (rRNA), hexokinase (HXK), glucose-6-phosphate isomerase (GPI), and phosphoglucomutase (PGM) genes of E. nuttalli isolates were compared with other reported isolates. The results showed clear differences among the Chinese E. nuttalli isolates and other isolates based on the SRP gene sequences. However, HXK, GPI, and PGM genes of these strains were similar to those of other isolates. The rRNA genes of E. coli and E. chattoni were also amplified and analyzed from these samples. The results suggested that host species might be a more important factor than geographic location in amebic genetic diversity. [ABSTRACT FROM AUTHOR]

Indosinian felsic volcanic rocks occurring in the Chongzuo area, Guangxi, were subject to prolonged weathering, which resulted in development of thick regolith hosting valuable ion-adsorption type REE resources. The figure below demonstrates a quantified REE eluviation-illuviation model for delineating the ion-exchangeable REEs enrichment pathway from source to sink. The source of ion-exchangeable REEs is mainly traced to a titanite + allanite + apatite assemblage, which together with other igneous minerals contributed REE ions to the weathering solution. After liberation of REEs by weathering, a large fraction of the rare earths is fixed by clay minerals (kaolinite + halloysite + illite assemblage) and the ions are present in an exchangeable form. A small fraction is adsorbed by Fe-Mn oxides and organic matter. REEs in zircon, monazite, and ilmenite are conserved; these minerals are the source of residual REEs in the regolith. • iREEs enrichment pathway in rhyolite regolith is delineated from source to sink. • Accessory mineral assemblage (titanite + allanite + apatite) is main source of iREEs. • The affinity of clay minerals to iREEs follows a halloysite > kaolinite > illite order. • There is formation preference for the felsic volcanic rocks-related iREEs deposits. Felsic volcanic rocks are an important source for generating ion adsorption-type rare earth element (REE) resources. To better understand the supergene enrichment of REEs related to felsic volcanic rock weathering, this study conducted an investigation of Indosinian felsic volcanic rocks from Guangxi, southwest China, which have been subjected to deep weathering. The weathering has formed large areas of thick regolith with the potential to host ion adsorption-type REE mineralization. The felsic volcanic rocks belong to the dacite–rhyolite series and are peraluminous, high-K, calc-alkaline, and REE-rich (325–376 ppm). Abundant REE-bearing accessory minerals are present in the felsic volcanic rocks, including titanite (average ΣREE = 15.1 wt%), allanite (average ΣREE = 14.9 wt%), and apatite (average ΣREE = 1510 ppm), and these three minerals contain an estimated 88.7% of the whole-rock REEs content. Significant REE enrichment is present in the felsic volcanic rock-derived regolith. A typical rhyolite-derived regolith profile has REE contents that increase from 376 ppm in the rhyolite to 1737 ppm in the regolith, representing an almost five-fold enrichment due to weathering. The REEs in the regolith are present in an ion-exchangeable form (iREEs), which accounts for 52%–87% of the total REEs present (TREEs). The occurrence of iREEs is closely linked to clay minerals, showing an affinity in the order halloysite > kaolinite > illite. Continuous operations of REEs by an eluviation–illuviation process from the source minerals (titanite + allanite + apatite) to sink minerals (kaolinite + halloysite + illite) results in an iREE-enriched zone in the middle and lower parts of the rhyolitic regolith. Notably, besides the studied Indosinian felsic volcanic rocks, there are multi-epochs of such lithology outcropped in South China. Their related iREEs mineralizations, however, are preferentially developed in the weathered terrains of early Yanshanian and Indosinian felsic volcanic rocks, and not in those of the Yanshanian and late Yanshanian felsic volcanic rocks. A comparison of the mineralized and barren units indicates that the iREEs mineralization hosted in felsic volcanic rocks regolith is controlled by some key endogenic and exogenic ore-forming factors. High initial REE concentrations in the unaltered felsic volcanic rocks, a suitable climate, and a relatively quiescent tectonic setting are favorable for the formation and preservation of iREEs mineralization. [ABSTRACT FROM AUTHOR]