Abstract:The Zetang island arc, located in Nedong County, southern Tibet, mainly consists of tonalite, trondhjemite, granodiorite and amphibolite. The Zetang island arc has been identified as a late Jurassic intra-oceanic arc. In this paper, integrated field geological survey, SHRIMP zircon U-Pb dating, whole rock geochemistry and Sr-Nd isotope study were carried out on the Zedang island arc to discuss magma source of amphibolite and its relationship with coeval granites. Some conclusions have been reached:① SHRIMP zircon ²⁰⁶Pb/²³⁸U dating of amphibolite shows a crystallization age of 159.1±7.2 Ma; ② Sr-Nd isotopic characteristics of amphibolite and granites are similar, with ⁸⁷Sr/⁸⁶Sr(t) ratios being 0.704 0~0.704 5 and εNd(t) values being +5.5~+6.1. ③ geochemical characteristics show low Sr, high Y, low Sr/Y radio, and enrichment of MREE. A comparison with other published data shows that tonalite, trondhjemite, granodiorite and amphibolite of Zetang arc were likely derived from the partial melting of the mantle wedge. Tonalite is a relatively primitive magma, and had been separated from the magma chamber before the full completion of amphibolite fractional crystallization. With the ongoing crystallization of amphibolite, the Sr/Y ratios, Cr, Ni and MREE values of residual magma increased step by step. Therefore, the fractional crystallization of amphibolite seems to have been the key factor for forming the high Sr/Y granites of Zetang island arc.

Abstract:The Late Carboniferous Liushugou Formation in the Bogda orogenic belt of the Eastern Tianshan Mountains is a bimodal volcanic rock composed of basalt and rhyolite, which was formed in the Late Carboniferous. Its SiO₂ content is between 46.18%~46.56% and 76.06%~76.25%, with obvious Daly component discontinuity. Basalt is characterized by rich sodium and poor potassium. Its TiO₂, Al₂O₃, Cao and MgO values are high, ΣREE is 75.54×10^-6~80.22×10^-6, LREE/HREE is 3.00~3.12, with enrichment of Ba,Rb and other large-distance lithophile elements (LILE) and incompatible elements (P,K), and relative loss of Ti, Ta, Nb and other high field strength elements (HFSE) and incompatible elements (U,Th). The Na₂O/K₂O ratio of rhyolite is 0.32~0.36, suggesting low titanium (Ti) and low magnesium (Mg) rhyolite. The ∑REE is 520.72×10^-6~595.26×10^-6, and the LREE/HREE is 5.60~6.53, which shows the enrichment of Rb, Th, K, La, Ce, Zr, Hf, Sm and other elements and the loss of Ba, U, Ta, Nb, Sr, P and Ti elements. The bimodal volcanic rocks of Liushugou Formation were formed in a continental rift environment with intraplate genetic characteristics. Basalts may be the product of partial melting of the transition phase from depleted spinel mantle peridotite to garnet mantle peridotite, which was contaminated by crustal materials. Rhyolites have typical geochemical characteristics of A-type granites.

Abstract:There exist three stages of magmatic emplacement in the Banbanshan complex massif, Shanyang County, on the northern margin of the South Qinling Mountains. They are the early monzogranite, the middle K-feldspar granite and the late diabase. In this paper, the authors studied the geochemistry and LA-ICP-MS zircon U-Pb age of the early monzogranite. The results show that the SiO₂ content of monzogranite is between 73.35% and 77.49%, the content of total alkali (K₂O+Na₂O) is 3.15%~7.19%, the Rittman index is 0.30~1.66, and the A/CNK ratio is 1.18~2.48, suggesting that they belong to peraluminous S type granite with medium and high potassium calc-alkaline nature. The total amount of rare earth elements varies greatly. Light rare earth elements are relatively enriched and heavy rare earth elements are relatively deficient. The rocks have a weak negative europium anomaly (δEu=0.70~0.89). Large ion lithophile elements Rb, K, Th, Ba are relatively enriched, and high field strength elements Nb, Ta, Ti, P are relatively deficient. It is shown that the Banbanshan monzogranite was formed in the same collisional tectonic environment and carried the geochemical characteristics of the volcanic arc environment, suggesting that the magma originated from the partial melting of the upper crust rocks and was metasomatized by the residual fluid formed by the dehydration of the subducted oceanic crust. The zircon U-Pb ages of the two samples are 743.2±6.1 Ma and 743.7±5.9 Ma, respectively, indicating that the Banbanshan monzogranite was formed in Neoproterozoic. Combined with the previous research results, it is considered that the Banbanshan area had been in the stage of paleooceanic subduction before 743 Ma, and after 743 Ma, the paleooceanic basin was closed, Rodinia supercontinent began to converge, and land collision occurred.

Abstract:Zongwulong tectonic belt is an important tectonic unit on the northern margin of Qaidam Basin, but its tectonic properties remain controversial. In this study, a diorite intrusion was recognized in central Xuji area of the Zongwulong tectonic belt, and its petrography, geochemistry, zircon U-Pb chronology and Lu-Hf isotopes were studied. The intrusion time of the diorite is 258±1 Ma;light rare-earth elements are enriched while heavy rare-earth elements are depleted, with weak negative Eu anomaly; it is relatively enriched in large ionic lithophile elements such as Rb, K and Sr, but strongly depleted in high field strength elements such as P, Ti and Nb. The content of Cr and Ni are 38.0×10^-6~92.8×10^-6 and 6.7×10^-6~14.1×10^-6 respectively, Mg^# values are 50~56, Rb/Sr ratios are 0.32~0.34, Ti/Zr ratios are 23.26~32.30, Ti/Y ratios are 145.29~163.97, Nb/Ta ratios are 10.45~11.45, Th/La ratios are 0.39~0.51, Ba/La ratios are 15.04~16.60, ²⁰⁷Pb/²⁰⁴Pb_(i) ratios are 15.602~15.611, zircon εHf(t) values are -8.52~-3.00, and the two-stage Hf model ages are 1 563~1 478 Ma[εHf(t)=-4.37~-3.00] and 1 827~1 790 Ma[εHf(t)=-8.52~-7.98]. It can thus be concluded that the magma was derived from mixture of the crust and the mantle, where the ancient crustal material was dominant. Combined with regional geological studies, it is suggested that the marginal rifting in the central and western regions of the Zongwulong tectonic belt should be later than that in the east.

Abstract:A few fresh graphite samples including a small amount of marble surrounding rock were taken from several large scale crystalline graphite mining areas in the north of Huangling basement dome for ore petrographic and geochemical analysis, and the source of ore-forming materials was discussed through corresponding analyses and diagrams. The graphite ore in this area occurs in a set of khondalite series of Huanglianghe Formation (Pt₁h), and the main ore types are graphite schist and graphite gneiss. According to the analyses of major and trace elements and carbon isotopes, the recovered ore protolith was a set of carbonaceous (sand) argillaceous sedimentary rocks, and the graphite carbon almost came from organic matter rather than from inorganic carbon in marble. According to the element composition and paleogeological evidence of the deposit, it is inferred that the source area of the Huanglianghe Formation was mainly Yemadong Formation (Ar₂y, tholeiitic), followed by Dongchonghe gneissic complex (Ar₂D, granitic), rather than the single "granitic rock as the source area" as previously thought. During the conversion process from the supply source to the ore-forming parent rock, strong geochemical changes took place rather than simple mechanical transfer of materials.

Abstract:Babu ultramafic-mafic rocks, located in the southeastern Yunnan Province, provide researchers a good opportunity to investigate the tectonic evolution of the branch of Paleotethys Ocean. The Yangwan copper deposit, which is hosted by basalts and breccia in Babu area, is considered as a good metallogenic prospective zone. However, the petrogenesis of the Babu ultramafic-mafic rocks and the age of Yangwan copper deposit are still controversial. In order to get the age of ore deposit, the authors applied Re-Os isotope dating to sulfides from the Yangwan deposit. Chalcopyrite and pyrite were picked out for Re-Os isotope analysis. Re-Os isotope dating yielded an isochron age of 269±3 Ma, with an initial ¹⁸⁷Os/¹⁸⁸Os ratio of 0.31±0.17. The well-defined Re-Os isochron, excluding the possible mixed isochron, represents the depositional age of sulfides, which means they were formed at the same time as ultramafic-mafic rocks (~270 Ma). The high initial ¹⁸⁷Os/¹⁸⁸Os ratio was interpreted as entrainment of seawater into pristine hydrothermal fluid. The characteristics of ore and the age of sulfides indicate that the Yangwan copper deposit is a VMS deposit. Though a comparative research on geochemistry between wall rock basalts and other rocks, it is held that all the data support the argument that the Babu ultramafic-mafic rocks are normal middle ocean ridge basalt (N-MORB)-type ophiolites at present. They probably represent the relics of the branch of Paleotethys Ocean.

Abstract:The monitoring of fossil weathering has always been a core problem in the monitoring and protection of fossil producing areas. Spectral technology provides a feasible way for monitoring fossil weathering. In this paper, ASD fieldSpec 4 portable spectroradiometer was used to study dinosaur bone fossils in Zhucheng, Shandong Province, which has been an important site for dinosaur excavation since the 1960. The results show that the fossils with different colors and weathering degrees have different spectral characteristics and obvious identification marks. The changing characteristics of their spectral curves are of great reference significance for the monitoring of fossil weathering in the future.

Abstract:In recent years, with the development of big data, geology has met new opportunities for development. Nevertheless, there are still relatively insufficient studies that use big data to study the relationships between different minerals. The basic components of minerals, rocks and ores usually exist in the form of coexisting assemblages. The occurrence of minerals is not random, but coexists and accompanies with each other according to some certain pattern. Mining co-occurrence pattern of these minerals through big data technology and mining the relationship between minerals can help better understand the relationships between minerals and can also play a positive role in guiding mineral prospecting. In this study, the authors used association rules, frequent pattern mining, network analysis, and community detection, which are commonly-used big data mining methods, to analyze the big data of the main components of ores. The dataset used in this paper was from the "Mineral Resources Data System" (MRDS) of the U.S. Geological Survey, which has collected a large number of mineral composition data from all over the world. The results show the following features:① Frequent mineral assemblages concealed in ore mineral composition dataset can be discovered through association rule mining. The frequent mineral assemblages are useful in mineral prospecting and the understanding of the relationship between minerals; ② The rules mined by association rule mining are a kind of quantitative reasoning rules. The interest measurement index can quantitatively represent the strength of rules. These rules are more quantitative and refined than the rules summarized by experience; ③ By means of network analysis, the relationship between main minerals in the ore dataset can be visualized dynamically, multi-dimensionally and quantitatively. Combined with community detection, the hidden relationship between minerals can be found from the ore mineral data set.

Abstract:The paper is a systematic collection of 109 new minerals approved by the Commission on New Minerals,Nomenclature and Classification(CNMNC) of the International Mineralogical Association(IMA) in 2015, by listingmineral name, crystallochemicalformula,crystal structuredata,physical and optical properties, locality of origin and occurrence, relationship with other minerals, source of mineral names, chemical reaction and spectroscopic characteristics.It's very meaningful that Chinese names of 109 new minerals have been examined and revised under the authority of Chinese Commission of New Minerals and Mineral Names.As a part of the comprehensive introduction to discovery and research of new minerals in the world,this paper will provide reference for the work of discovering, researching and naming new minerals in China and promote the standardization of Chinese names of mineral species.