Abstract:Porphyry deposits are globally the main source of copper and molybdenum, and their formation is related to the epigenetic emplacement of intermediate to felsic porphyry intrusions. The fine ore.forming processes and fertility assessments of porphyry deposits have been an important frontier since the beginning of this century. As the most common and chemically stable accessory minerals in intermediate to felsic rocks, zircon and apatite have been widely used in the study of magmatism and mineralization in recent years. On the one hand, this is due to the rapid progress and popularization of in.situ analysis technology represented by LA.ICP.MS in recent years, which makes it possible to accurately obtain information of mineral trace elements; on the other hand, the chemical composition of zircon and apatite contains rich diagenesis and mineralization information, including age, temperature, oxygen fugacity, water content, S and Cl content, etc. Combining these indicators can reveal the evolution and fine processes of magma.mineralization. This paper reviewed the main progress in the ore.forming processes and fertility assessments of porphyry deposits by zircon and apatite, especially in discriminating rock types, petrogenesis, magma sources, estimating parent magma composition, discriminating ore deposit types, tracing sources of ore.forming fluids, revealing fluid metasomatism and alteration zoning of porphyry deposits, quantifying post.mineralization exhumation and preservation. Furthermore, a summary of problems and challenges in the study is presented. Finally, some suggestions are proposed for the application of zircon and apatite in study of porphyry deposits in the future.

Abstract:As one of the most important members of the metal stable isotope family, zinc isotopes have attracted quite a lot of attention by international scientific community since the last century. In the 21st century, with the development of multi.collector inductively coupled plasma.mass spectrometry (MC-ICP-MS), the applications of zinc isotope have been greatly expanded and deepened in the Earth and planetary science. Here we provide a relatively detailed overview of research on zinc isotopes, including the reference materials and analytical methods of zinc isotopes, the zinc isotope compositions of the main reservoirs in nature, the behavior and fractionation mechanisms of zinc isotopes in different geological processes, and recent advances on zinc isotopes in the four fields of Earth science: ① tracing the deep carbon cycle, recycled oceanic materials and the origin of compositional transition of alkaline basalts; ② tracing the sources of ore.forming material, microbial mineralization, and indicating mineral exploration; ③ unrevealing the origin and evolution of the moon; ④ indicating the primary productivity, biogeochemical processes, and the mechanism of the mass extinction at the end of Permian. In the future, with the development of zinc isotope microarea in situ analysis technology, zinc isotopes will be widely used in geosciences, especially in ore deposits, and biomedical sciences.

Abstract:The Miocene K.rich adakitic rocks (KARs) containing dark microgranular enclaves (DMEs) in southern Tibet have been thought to be products of magma mixing/mingling between melts derived from partial melting of pre.existing continental crust in the stability field of garnet and the coeval mantle.derived ultrapotassic volcanic rocks. To test this hypothesis, we conduct an integrated study of petrology, zircon U-Pb dating, mineral geochemistry, and whole.rock elemental and Sr.Nd isotopic geochemistry on the Miocene Mayum KARs and their DMEs from the Zhongba micro.terrane in the western segment of the Yarlung Zangbo suture zone. The results show that the KARs and their DMEs have similar emplacement ages (~17.5 Ma), mineral assemblages (quartz+feldspar+amphibole+biotite) and mineral compositions, but the DMEs contain more amphibole and biotite, and have lower K2O and SiO2, and higher MgO, TiO2 and P2O5 contents than the KARs. In addition, the KARs and their DMEs have similar whole.rock Sr-Nd isotopic compositions: the KARs have （87Sr/86Sr） i of 0.70933~0.70950 and ε Nd( t ) of 8.17~ 6.72; the DMES have （87Sr/86Sr） i of 0.70933~0.70941 and ε Nd( t ) of 7.55~ 6.57. These features indicate that the DMEs are most likely fine.grained cumulates or autholiths related to the host KARs, rather than mixtures formed by magma mixing/mingling of the host KARs and the coeval ultrapotassic volcanic rocks with higher K2O contents. Combined with regional geological data, we conclude that the Mayum KARs resulted from partial melting of earlier crustal components that are rich in K2O in the stability field of garnet, and did not mix or mingle with the coeval ultrapotassic volcanic rocks.

Abstract:Leucogranite is an ideal object to study the composition of shallow crustal and geodynamic process of the collision orogenic belt, and also an important carrier of rare metal mineralization. The Pagele two- mica granite studied in this paper are developed in the southwest of the compound granitic batholith in the Nianqingtanggula Mountain, Gangdese. It is produced in the form of stocks and apophyses, and occasionally contains beryl. Precise zircon U- Pb dating shows that its crystallization age is 18.4 Ma and 17.6 Ma, corresponding to Miocene. The rock has high content of SiO- 2(72.78%~75.53%), K- 2O(4.83%~5.52%)and A/CNK(1.04~1.12), and low content of Al- 2O- 3(13.42%~14.60%), MgO(0.10%~0.24%), TFe- 2O- 3(0.86%~1.65%), and belongs to the peraluminous high- K calc- alkaline and shoshonitic granite. (87Sr/86Sr)- i=0.712139~0.713545, ε- Nd(t)=〖CD*2/3〗9.0~〖CD*2/3〗8.3, tDM- 2=1211~1468 Ma, 206Pb/204Pb=18.797~18.841, 207Pb/204Pb=15.755~15.785, 208Pb/204Pb=39.425~39.519, ε- Hf(t)=〖CD*2/3〗6.8~2.0, tDM2=970~1529 Ma, showing that the source was composed of main crust- derived melts (70%~80%) originating from the Proterozoic Nianqingtanggula Group metamorphic rocks in the middle and upper crust, and a small amount of mantle- derived melts (20%~30%). LREE/HREE=4.30~9.61, (La/Yb)- N=3.61~13.42, δEu=0.16~0.34, Differentiation Index (DI)=95~97, K/Rb=76.51~116.39. Rb, Th and U are relatively enriched. P, Zr, and Ti are strongly depleted and the Rb- Ba- Sr differentiation is obvious. They indicate that the magma may have undergone strong crystallization of K- feldspar, plagioclase, zircon, apatite and biotite. Combined with regional geological data, it is believed that the Miocene granite in the Nianqingtanggula area, including the Pagele mica granite, probably formed under the background of the tectonically weak belt in the upper- middle crust caused by tearing of the subducted Indian continent plate. The upwelling of asthenosphere induced the mantle magma to invade along the weak zone, and caused the dehydration and melting of muscovite in the pelitic metamorphic rocks in the upper- middle crust to form the crust- derived magma. Subsquently, the mantle and crust- derived magmas mixed and underwent different degrees of crystal differentiation. The rare occurrence of beryl in the Pagole two- mica granite may be related to the enrichment mechanism of partial melting of beryllium- rich upper- middle crust, strong crystallization differentiation and F- Be complexation. The beryllium- rich granitic pegmatite, evolved from the Pagole beryllium- rich two- mica granitic magmatic system, is likely to have great beryllium mineralization capacity.

Abstract:The magmatic hydrothermal polymetallic metallogenic belt in the northeastern part of the Gangdese polymetallic belt formed in the initial stages of Indian- Asian collision. This belt contains various types of deposits with different metal associations. Previous studies were mainly focused on the Pb- Zn, Mo and Fe- Cu metallogenic systems, leading to limited understanding of the Cu metallogenic system. The Chengbabu deposit, which located in the south of the northeastern Gangdese metallogenic belt, is the only skarn deposit dominated by Cu mineralization. Thus, it provides a good opportunity to study the metallogenesis and regional exploration potential of Cu in the belt. The ore bodies in Chengbapu mainly occur in skarns that are interbedded between the Lower Cretaceous Linbuzong Formation slate and the Upper Jurassic Duodigou Formation limestone. Ore minerals (chalcopyrite, sphalerite and molybdenite) mainly occur in the quartz sulfide stage. The Re- Os isotope of molybdenite from skarn gives an isochron age of 59.0±0.8 Ma. LA- ICP- MS zircon U- Pb dating of diorite and granodiorite porphyry associated with the mineralization are 58.9±0.9 Ma and 58.7±0.8 Ma, respectively. These data indicate that the Chengbapu deposit was formed in the main India- Asia collision, which are similar to the ages of other deposits in the northeastern Gangdese polymetallic metallogenic belt. The diorite and granodiorite porphyry, identified as I- type granites, are genetically related. Granodiorite porphyries are derived from diorite by fractional crystallization of amphibole and plagioclase. For diorite and granodiorite porphyry, zircon εHf(t) values range from +0.3 to +7.6, and εNd(t) values range from 0.1 to +0.5. It indicates juvenile lower continental crust source region which has been reworked by mantle- derived material. Zircon εHf(t) contour map of the northern Gangdese polymetallic metallogenic belt indicates that the mineralization is controlled by crustal structure and magma source. It also suggests that the Pb- Zn deposits were mainly developed in the area where have ancient crustal sources. The transition region of the juvenile and ancient crustal sources, and south of Chengbapu deposit have potential to find large- medium Cu deposits.

Abstract:The Yidun Terrane, located in the eastern Tibetan Plateau, is a key area to study the tectonic evolution of the Tibetan Plateau and the Paleo- Tethys. To date, its paleogeographic position and possible tectonic evolution during the early Paleozoic remain unclear. Detrital zircons from siliciclastic rocks record a wealth of information about their source region and have been widely used to unravel sedimentary provenance and paleogeographic construction. In this study, we conducted detrital zircon in- situ U- Pb dating and Hf isotope analysis of three lower Paleozoic meta- sedimentary rocks in the terrane. The results show that these samples have multi- peak detrital zircon age patterns, their U- Pb ages are mainly grouped into ca.2535~2350 Ma, ca.1000~900 Ma, ca.890~750 Ma, and ca.590~520 Ma, and their corresponding εHf(t) values are 8.8 to 13.1, 11.8 to 10.0, 20.1 to 12.6, and 27.6 to 6.1, respectively. Combining these results with previous studies, we consider that the ca.2535~2350 Ma and ca.890~750 Ma detrital zircons were predominantly sourced from the nearby Songpan- Ganze Terrane and South China Block, whereas the ca.1000~900 Ma and ca.590~520 Ma detrital zircons were likely derived from the Rayner- Eastern Ghats, Prydz- Darling, and Kuunga orogens in the East Gondwana. By comparing the difference in sedimentary provenance between the lower Paleozoic and Neoproterozoic siliciclastic rocks in the Yidun Terrane, as well as those lower Paleozoic sedimentary rocks in the nearby terranes, we suggest that the Yidun Terrane was probably collaged to the India Block during late Ediacaran to early Cambrian (ca.570~520), and became part of the Gondwana supercontinent. In the early Paleozoic, the Yidun Terrane was located on the northern margin of the East Gondwana, adjacent to the Qiangtang and Tethyan Himalaya terranes.

Abstract:The Yangla Cu deposit is the largest Indosinian Cu deposit in the middle segment of the Jinshajiang suture zone. The ore bodies are mainly developed in the periphery of the granodiorite and between carbonate and metamorphic sandstone with stratiform- like shape. Its genesis has been debated for decades with ideas including sedimentary exhalative, skarn, and superimposed models. In this contribution, garnet U- Pb age and the composition of garnet and magnetite were determined to further define the timing and genetic type of this deposit. The analysis showed that the garnets have U, Th and Pb contents of 1. 18×10-6~6. 69×10-6, 0. 04×10-6~1. 43×10-6, 0. 11×10-6~1. 16×10-6, respectively, and yielded an intercept age of 231. 0±5. 3 Ma (2σ, n=32, MSWD=2. 1). This represents the timing of skarn formation coeval with the generation of granodiorite. In combination with magnetite showing compositions similar to skarn deposits around the world, it is confirmed that the Yangla is a typical skarn Cu deposit. Garnets belong to andradite and are mainly characterized by enriched LREE and depleted HREE, which was controlled by both crystal chemistry and adsorption. In combination with their high Eu positive anomalies and low U concentrations, it is suggested they formed in a slightly low pH, enriched Cl, and relatively oxidized environment. Compared with other Cu skarn deposits worldwide, garnets at Yangla contain significantly higher Sn (485×10-6~7433×10-6, average 3931×10-6) and W (0. 20×10-6~736×10-6, average 156×10-6), and magnetites also have higher Sn (115×10-6~778×10-6, average 405×10-6). This is similar to the characteristics of W- Sn skarn deposits around the world. Combined with garnet U- W and Sn- U diagrams, it is proposed that W and Sn mineralization may have developed in the ore field.

Abstract:The supergiant Huimin iron deposit is located in the eastern part of the Changning- Menglian suture belt in the Sanjiang compound orogenic belt, which notably features volcanoclastics- hosted, magnetite- siderite association, as well as pervasive hydrothermal alteration. At present, the genesis of the deposit is still debated due to controversy in the age of the ore- bearing strata. Detailed field observations reveal two tectonostratigraphic units separated by an unconformity, both of which belong to the Huimin Formation of the Lancang Group. The lower unit is the Middle to Late Ordovician volcanic- sedimentary rocks with arc affinity, which has been intensely modified by the Paleo- Tethyan subduction, and thus exhibits features of tectonic mélanges. Locally, iron and copper mineralization occurred in the older unit. The upper unit consists of basalt, andesite, crystal- rich tuff and hydrothermal siliceous rocks, where numerous iron- layers occurred. These iron layers form the main orebodies. This volcanic succession contains at least three volcanoclastic cycles with mostly conformity contacts between them. The iron ore bodies are stratiform- like and/or lamellar style in shape, and few are steeply- dipped veins and veinlets. Obviously, the mineralization was syn- sedimentary. New zircon LA- ICP- MS U- Pb dating results show that the ore- hosted volcanic rocks were emplaced during 235 to 214 Ma with the volcanism age peaking at 230 to 225 Ma. The Late Triassic volcanic rocks show arc- signatures geochemically, and likely formed in a forearc basin due to the eastward subduction (at present geographic coordination) of the Paleo- Tethys Ocean. These data, combined with the previously published data, suggest that the supergiant Huimin iron deposit is a volcanic- sedimentary deposit formed owing to subduction- related volcanism during the Early Mesozoic. Our new data and ideas presented in this paper shed light on understanding the mineralization of similar iron deposits in the adjacent regions of the Huimin iron deposit, and are helpful in guiding further prospecting.

Abstract:The Machangqing Cu- Mo deposit, located in the Sanjiang Tethyan metallogenic belt, is a polymetallic deposit related to the intrusion of alkaline porphyry in the Himalayan period. Previous studies have shown that the Machangqing Cu- Mo polymetallic deposit was formed in a porphyry- skarn metallogenic system. However, due to the lack of systematic mineralogical research, a mineralization process and metallogenic effects of skarn are still unclear, limiting a comprehensive understanding of the mineralization process of this deposit. Herein, this paper considers garnet in skarn mineralization in Machangqing deposit as the research object, and uses H- O isotope, electron probe (EPMA) and LA- ICP- MS in- situ microregion technology to carry out isotope and composition analysis to define the source of ore- forming fluids and invert the evolution process of ore- forming fluids. The garnets can be divided into early euhedral garnets (Grt I) and late anhedral type (Grt II). The Grt I, coexisting with the pyroxene, pyrite and chalcopyrite, belongs to the grossular- andradite garnet solid solution (And49. 37~99. 58 Gro0~49. 79). The Grt II has elevated Fe compared to Grt I, and mainly consists of andradite (And67. 5~99. 85 Gro0~31. 84). Both the types of garnets are enriched in Th, U, LREEs and Nd, depleted in Ba, Sr, Hf and Nb. Based on the chemical compositions of garnet, the Grt I may have formed under mildly acidic, oxidized and low W/R conditions, whereas the Grt II may have formed under acidic, oxidation, and high W/R conditions. In addition, the δDV- SMOW values and δ18Ofluid values of these garnets range from 122. 6‰ to 98. 6‰ and 5. 95‰ to 8. 25‰, respectively, implying that the hydrothermal ore- forming fluid originated from magma- derived fluid. A comprehensive consideration of data indicated that the oxygen fugacity and temperature of the ore- forming fluid presented a decreasing trend during the skarn mineralization process, and the pH of the fluid gradually changes from acid to weak acid neutral. This process may have been the main mechanism to trigger the precipitation of skarn type mineralized copper molybdenum sulfide in the Machangqing deposit.

Abstract:The distribution of Permian- Triassic magmatic rocks in western Yunnan Province is still unclear, resulting in controversy regarding the Paleo- Tethyan tectonic evolution model. Here, we present new LA- ICP- MS zircon U- Pb, zircon Hf isotopes whole- rock major and trace element, and Sr- Nd isotopic data for the Shuixie grabbos of the western Langping- Simao basin in the Sanjiang Orogen, SW China. The zircon U- Pb ages of two samples from Shuixie gabbros are 237.8±3.4 Ma and 240.8±3.3 Ma respectively, representing their crystallization age and belonging to the Middle Triassic. The samples have high Na2O/K2O (3.81~49.14), and are enriched in LILEs ( such as Ba, Rb, Th, U), depleted in HFSEs (such as Nb, Ta). The REEs are weakly fractionated, and the LREEs are weakly enriched. The δEu values ranges from 0.87 to 1.07, without obvious Eu anomaly. Zircon εHf(t) values are all positive, mainly ranging from +5.67 to +15.75. The initial 87Sr/86Sr ratio of the whole rock ranges from 0.70453~0.70776, and εNd(t) values are all positive, ranging from +4.9 to +5.2. Geochemical characteristics show that Shuixie gabbros originated from the partial melting of the depleted mantle, and the fractional crystallization of mafic minerals and Fe- Ti minerals occurred during the magmatic evolution. Shuixie gabbros are located at the junction of the Jiangda- Weixi arc and the Yunxian arc, and occurs in the continental margin arc environment. These dykes, together with the Zadoi arc, the Jiangda- Weixi arc and the Yunxian arc, are the products of the subduction of the Paleo- Tethys main ocean basin, thus forming an arc magmatic belt with a length of tens of thousands of kilometers.

Abstract:The Huachangshan lead-zinc deposit in Yunnan is a typical MVT lead-zinc deposit formed in the fold-thrust belt, with most of the ore bodies located along and on both sides of the faults. In this study, four sets of faults with different occurrences were identified by cataloguing adits, three of which have developed hydrothermal fluids that include a non-mineralized fluid, a copper-silver fluid, and a lead-zinc fluid. All of them develop hydrothermal calcite during the hydrothermal process. As a result of in-situ rare earth element (REE) analysis, it is concluded that calcites originated from hydrothermal fluids unrelated to magmatism. In addition, calcites display different REE distribution patterns, and different positions on lg(Y/Ho)-lg(La/Ho) and Yb/Ca-Yb/La (atomic ratios) coordinate diagrams. These data indicate that the three fluid sources are different or that they have been modified from cogenetic fluid. The carbon and oxygen isotopic values of the calcites indicate a tendency for dissolution and reprecipitation of marine carbonate rocks within the basin. The oxygen isotopic characteristics of calcites indicate that the three fluids originated from basin brines and lead-zinc fluid mixed with meteoric water. Based on the detailed analysis of the fault activities and hydrothermal fluid characteristics, it is considered that the tensile faults after regional thrust fault are the main ore-controlling faults in the Huachangshan lead-zinc deposit.

Abstract:As one of crucial mineral resources, niobium (Nb) is used in superconducting materials and aerospace because of its special superconductivity, high melting point, corrosion resistance, wear resistance. Nb is an absolutely essential ingredient for high- tech industry development. The global niobium mineral resources are rich but not uniformly distributed as highest values (95%) are in Brazil. Although China is poor in niobium resources, the niobium consumption is more than a quarter of total world consumption. The vast majority of the niobium resources depend on import and there is a high risk of “bottlenecks” in China. Recent studies have shown that ore beds of the lower Xuanwei Formation (Late Permian) are highly enriched in Nb2O5 (220 μg/g), LREE (oxides of La- Lu+Y) (850~5500 μg/g), and Ga (50 μg/g), and have reached industrial grade in the Xuanwei- Weining area. The prospective reserves of niobium (Nb), gallium (Ga) and rare earth elements (REE) respectively exceed 110000 tons, 400000 tons, 20000 tons. They indicate a potential to discover more resources. Despite spatial distribution and geochemical element distribution of this type of deposit having been intensively studied, the occurrence state, migration and enrichment mechanism of Nb are still unclear limiting a clear understanding of the metallogenic mechanism. Working with Nb deposit of the Xuanwei Formation and basalt located at the bottom, this study aims to reveal the occurrence state and metallogenic mechanism by X- ray powder diffraction (XRD) and Electro- Probe Microanalyzer (EPMA). The results indicate that the main Nb- carrying mineral is anatase. The basalt generally contains a special Nb- rich mineral named titanite in the Xuanwei- Weining area. It was demonstrated that anatase is generally formed by weathering alteration of titanium minerals such as titanite. Meanwhile, some titanite weathered away to become anatase. In this way, Nb may dissolve from titanite during weathering of the titanite - rich basalt and enter into anatase. Titanite, as a major contributor, may control the migration and enrichment mechanism of niobium during the weathering process.

Abstract:The Lujing uranium ore field which is located in the southwest part of Taoshan- Zhuguang metallogenic belt is one of the most important granite type uranium ore field in South China. This ore field is dominated by the uranium mineralization related cataclastic alteration. The Xiaoshan uranium deposit is one of newly discovered cataclastic alteration granite- type deposits during recent years. Chloritization is the most important alteration type and prospecting indicator of the cataclastic alteration granite- type uranium deposits. However, the course of chloritization and its relationship with uranium mineralization has not been paid much attention. In this study, the mineralogy of chloritization from hydrothermal zone that was uncovered by drill core ZK- 1 in Xiaoshan deposit has been carried out. The following conclusions have been reached in this study. ①There are four types of chlorites, including chlorite of biotite alteration, chlorite of feldspar alteration, chlorite vein/veinlet filling in fissures, chlorite closely associated with uranium minerals. ② The chlorites are mainly plotted in the brunsvigite area, partly plotted in the pycnochlorite. ③ The formation temperature of chlorites varies from 213.5℃ to 249.8℃, at an average of 233.4℃, suggesting the chlorites were formed under medium to low temperature conditions. ④ The chlorites were formed under the reduced condition with low oxygen fugacity and high sulfur fugacity through two formation mechanisms of the dissolution- precipitation and the dissolution- migration- precipitation. The uraninite, monazite and xenotime are redissolved to form coffinite- thorite. ⑤ The chloritization has changed the properties of wall rocks, the occurring state of uranium in rocks and physicochemical environment and promoted the activation, migration and precipitation of uranium.

Abstract:Our study involved zircon U- Pb dating and in- situ Hf isotope, and whole- rock geochemical analyses for the medium- coarse- grained biotite granites associated with tin mineralization and the fine- grained hornblende biotite granites far away from the ore bodies from the Samoeng deposit, in Thailand. Zircon U- Pb ages show that the two granites were formed at 210.9±1.1 Ma and 206.5±1.0 Ma, respectively. Both granites are characteristic of rich in alkali with total alkali content of 5.81%~8.22%, relatively rich in Rb, Th, and Pb, weakly to strongly peraluminous (A/CNK=1.01~1.14) and low in TFeO/MgO (0.75~3.54) and 10000Al/Ga (2.21~2.66) values. The medium- coarse- grained biotite granites have primary muscovite and relatively high K2O/Na2O (1.56~2.50) and Rb/Sr (2.26~2.60) ratios, with high P content in their zircons, belonging to typical S- type granites. While the fine- grained amphibole biotite granites are wide development of amphibole, and have relatively low K2O/Na2O (0.45~1.11) and Rb/Sr (0.54~1.18) ratios, with low content of P in their zircons, which can be classified as typical I- type granites. The two granites have quite different Hf isotopic compositions. The medium- coarse- grained biotite granites have relatively low εHf(t) values (20.0 to 8.9), with the corresponding two- stage Hf model age of 1.8 to 2.5 Ga (average values of 2.0 Ga). In contrast, the fine hornblende biotites granite have relatively high εHf (t) values (4.6 to 5.5), with the two- stage Hf model age of 0.9 to 1.5 Ga (average values of 1.1 Ga). Both two granites were formed in a post- collisional tectonic transition (from compression to extension) related to the closed Paleo- Tethys Ocean, and have similar magmatic temperatures and moderate fractionated (DI=79.6~88.0, SiO2=67.57%~72.97%, and zircon Zr/Hf values=29.8~64.9). The mid- coarse- grained biotite granites were suggested to be derived from Paleoproterozoic metagreywackes with low magmatic oxygen fugacities (average ΔFMQ 4.93), whereas the fine- grained amphibolite biotite granites mainly originated from juvenile meta- igneous rocks with the input of ancient meta- sedimentary component, and have relatively high magmatic oxygen fugacities (average ΔFMQ 2.76). We think the nature of the source region and magmatic oxygen fugacity condition could be the most important controlling factors for tin mineralization in the Samoeng deposit.

Abstract:The red carbonate rock is a kind of representative sedimentary rock with purple- red colors of the Ordovician in South China, and may contain special palaeoenvironmental information. There is a well exposed thick red carbonate rock section in the Sanbaidong area of Xiangxi, which is mainly developed in the Dawan Formation and the Guniutan Formation. This paper studied 355 carbon- oxygen isotope, Mn- Sr element samples and 10 conodont samples on it. According to the restriction of conodont samples from these formations, the bottom boundary of the Dawan Formation may be near the top boundary of the Florian Stage, the boundary between the Dawan Formation and the Guniutan Formation may be in the lower to middle part of the Darriwilian Stage, and the top boundary of the Guniutan Formation is near the top boundary of the Darriwilian Stage. With δ13C- δ18O correlation analysis and Mn- Sr element evaluation, it is considered the samples are not strongly affected by diagenesis. 355 samples show that the δ13C and δ18O of the Sanbaidong section are low amplitude and high frequency fluctuations. The δ13C are between 0.38‰ to 1.67‰, while the δ18O are between 9.34‰ and 7.21‰. Among them, BDNICE and MDICE are two global isotopic events that can be compared with this section, and LDNICE can be compared indirectly. In addition, there are two unnamed δ13C isotope shifts with potential comparative value. In general, there is an increasing trend of δ13C from east to west along the equator on the north Gondwana. The fluctuation amplitude in South China is generally smooth, which may have been caused by the difference in bottom seawater stratification in different blocks during the seawater circulation. Based on the δ13C and δ18O calculation, the red carbonate rocks should contain marine characteristics with middle to high palaeosalinity that increases upwards. Combined with the lithology, color, palaeontological quantity of the section and regional palaeogeography, it is believed that there may be an oxidation event at the bottom of the Dawan Formation, and the red carbonate rocks may be the product of the temporary relative sea level decline superimposed oxidation events.

Abstract:In order to clarify the stratigraphic age of ore- bearing of sandstone- type uranium deposit in the Zhungashun area of Chuanjing depression, Erlian basin, coal seam and dark gray mudstone samples in the borehole were collected in this study to carry out palynology research. The sporo- pollen of ore- bearing strata has the characteristics of Cicatricosisporites- Cyathidites- Abietineaepollenites- Pinuspollenites- Classopollis assemblage, which indicates that the stratigraphic age is the Apthian to Albian of Early Cretaceous. Combined with the U- Pb age spectrum analysis of detrital zircons, it is considered that the main sedimentary provenance of the sedimentary period came from the Baoyintu Rock Group of the Bayinhanggai uplift in the southeast, and a small part came from the ophiolite tectonic melange of Solunshan uplift in the north. According to the statistical analysis of palynological vegetation types, climatic zone types and dry- humidity types in the Zhungashun area, the ancient vegetation was dominated by coniferous, followed by evergreen broad- leaved forest, and a certain number of shrubs and herbs. Spores and pollen of Pinaceae, Dicranopteridaceae and Selaginellaceae are mixed with tropical- subtropical plants such as Cephalotaxaceae, Cyatheaceae and Encyclopedia, indicating that the palaeoclimate was humid subtropical climate. Although the number of hygrophytes in the Baiyanhua Formation increased, the number of xerophytes such as Classopollis and Jugella increased significantly, while coniferous and evergreen broad- leaved forests decreased, indicate a trend towards semi- arid climate. The mud- sand- mud stratigraphic structure of the Baiyanhua Formation in the Lower Cretaceous is stable. The sand body with good permeability and high reduction components is a favorable prospecting target layer, which provides rich organic matter and good preservation space for the reduction and precipitation of uranium- bearing fluids.

Abstract:Although nearly thirty years of research on internal- wave and internal- tide deposits in stratigraphic record are available, there is a lack of studies on the origin of internal- waves and internal- tides. This has seriously limited further research on fluid interactions between different flows in deep- water complex hydrodynamic conditions, and understanding the relationship between internal- wave and internal- tide deposits and hydrocarbon generation and migration, further aggravated by the lack of biological and trace fossils.Here we focus on the deep- water deposits of the Upper Ordovician Lashenzhong Formation in the Zhuozishan area of western Ordos basin, and comprehensively investigatetheir internal- wave and internal- tide deposits by combining sedimentary geochemistry and sedimentology based on the detailed field work. The results show that the bi- directional cross- laminations and wave- ripple laminations could exist have together and were mainly developed in the Tc division of complete or nearly complete Bouma succession, wherethe host lithologies are grayish green thin- to medium- bedded fine- grained sandstones, siltstones, argillaceous siltstones and silty claystones. The characteristics of depositional aqueous media include fewer seawater properties in general, oxidation- reduction stratification, salinity inversion, no effects of hydrothermal fluids and relatively strong hydrodynamic force. Combined with the existing fact of turbidity current reflections, these results perhaps suggest that the Lashenzhong Formation was deposited in the slope to basin plain environments of confined sea, and their internal- wave and internal- tide deposits have obvious characteristics of event action which could have co- existed with large biological (graptolite) and trace fossils because of the pycnoclines in which the internal- waves and internal- tides were formed and related to the reflection of turbidity currents rather than thermocline. The new type of internal- wave and internal- tide deposits discovered in this study have an important significance for oil- gas prospecting of deep- water tractive current deposits.

Abstract:In this paper, we undertook laser ablation- multicollector- inductively coupled plasma- mass spectrometer (LA- MC- ICP- MS) investigations on zircons for U- Pb geochronology, zircons in- situ Hf isotopic and whole- rock geochemical analysis on the Taohuagou dyke in Liangcheng, northern margin of the North China craton (NCC). Based on the newly obtained data, we identified the emplacement age, petrogenesis, and tectonic setting of the mafic dykes in Liangcheng and further discussed their implications for the reconstruction of the Rodinia supercontinent. The results show that the Taohuagou dyke was the product of mafic magmatism in the early Neoproterozoic (903±15 Ma), belonging to tholeiitic series, with high TFeO (12.78%~16.30%) and TiO2 (2.59%~3.31%) contents, and low MgO (2.87%~3.83%), Cr (32.7×10-6~42.0×10-6), Ni (11.6×10-6~14.5 ×10-6) contents, and low Mg# values (29~38). They are enriched in light rare earth elements (LREEs), Rb, Pb, Zr, and Hf elements, and depleted in Ba, Sr, Nb, Ta, Ti and Eu (Eu/Eu*=0.74~0.83) elements. The zircon in- situ εHf(t) of Taohuagou dyke ranges from 2.4 to 13.4, with single- stage Hf model (tDM1) ages ranging from 892 to 1357 Ma. The comprehensive study shows that the Taohuagou dyke in Liangcheng was formed in an intracontinental rift tectonic setting. The parent magma originated from the deep (~80 km) asthenospheric mantle, and pyroxenite components were involved in the source area. The magma experienced the fractional crystallization of olivine, clinopyroxene, plagioclase, Fe- Ti oxides and apatite, and was contaminated by the continental crust during emplacement. Geochemical data show that the early Neoproterozoic mafic magmatism in the NCC recorded the transition from intracontinental rifting to continental breakup. Geological and paleomagnetic data support that the NCC was adjacent to Laurentia in the early Neoproterozoic. However, further paleomagnetic research is needed to clarify whether it was adjacent to the So Francisco- Congo craton.

Abstract:The eastern Nanling is one of the richest areas for nonferrous, rare earth, rare and radioactive mineral resources in China, especially quartz vein wolfotite, hydrothermal uranium and ion- adsorption rare earth, which are closely related to biotite granites in the Yanshanian period, especially in early the Yanshanian period. On the basis of previous studies, this paper summarizes the controlling characteristics and role of stratigraphy, tectonics and magmatic rocks on the occurrence and distribution of mineral resources in the eastern Nanling, summarizes the basic characteristics of deposit types and spatial and temporal distribution, and analyzes the prospecting direction of important minerals in the eastern Nanling. It is emphasized that the eastern Nanling is characterized by extensive exposure of Precambrian strata, complex structure, linear structure and ring structure controlling the ore to varying degrees, frequent magmatic activities, especially granitoids. Different ore- controlling factors restrict the development of different mineral species. The eastern Nanling is rich in minerals, with 543 mineral deposits of 58 types of minerals and 18 types of ore deposits. During the Yanshanian period, especially in its early stages, the endogenic ore deposits were mostly distributed around the middle- acidic rock mass, while the exogenic minerals were scattered all over the region and sited in the convenient transportation location. The metallogenic prospecting areas are proposed for W, Sn, fluorite and hydrothermal resources in Wanyangshan- Zhuguangshan, W, Sn, rare earth, Pb and Zn resources in Chongyuyou- Sannan, and W, Sn, rare earth, rare, Pb, Zn, Ag, Au and fluorite resources in Xingguo- Yudu- Ganxian. It is pointed out that it is of great significance to strengthen the search of, and research on hydrothermal uranium ore, quartz vein wolframite and co- associated tin deposits, ion- adsorption rare earth deposits, fluorite, kaoline, geothermal and other minerals, and to strengthen the deep and peripheral prospecting, for the geological prospecting and the sustainable and high- quality development of mining industry in the eastern Nanling.

Abstract:Gold- rich porphyry- skarn deposits produce most tellurium resources, and the temporal and spatial distribution regularity of other types of tellurium resources needs to be discussed. In the national dynamic evaluation project of potential mineral resources, the features, type and spatiotemporal distribution of tellurium resource in China are studied, the metallogenic regularities of tellurium deposits in China is summarized. This paper introduces the characteristics and problems of tellurium resource in China. Data of 45 tellurium deposits is collected, the tellurium deposits in China are divided into six prediction types, namely alkaline intrusive rock type, carlin type, epithermal type, porphyry- skarn type, orogenic type and copper- nickel sulfide type. The metallogenic period of tellurium deposits in China is divided into Proterozoic, Paleozoic, Mesozoic and Cenozoic. 9 tellurium metallogenic belts are divided. The spatiotemporal distribution feature of each tellurium deposit type is summarized. 34 tellurium- related metallogenic series are determined and the metallogenic pedigree of tellurium deposits in China is established. The comprehensive study shows that tellurium ores in China are dominated by Late Paleozoic and Mesozoic epithermal, porphyry- skarn and copper- nickel sulfide deposits in the North and Northeast China, orogenic deposits in the Xiaoqinling- Xiongershan region, and porphyry- skarn and copper- nickel sulfide deposits in the middle and lower reaches of the Yangtze River and Yunnan- Sichuan- Guizhou regions.

Abstract:The Jiama porphyry- skarn type copper polymetallic deposit is an important super- large porphyry- skarn- hornstone type deposit in theGangdise metallogenic belt. As the first solid mineral research drill in the Qinghai- Tibet plateau, the 3000 m deep drill penetrated the hornstone, skarn and porphyry ore bodies into the deep barren core, which is of great significance to reveal the metallogenic system of the Jiama porphyry. In this paper, short wave and thermal infrared technique were applied to test and analyze the spectrum of the 3000 m deep drill of the Jiama mine, the spatial distribution and content variation of the main minerals in different metallogenic systems are identified, and the significance of exploration indication of important altered minerals is also revealed. The results show that biotite, albite, orthoclase, quartz, muscovite and chlorite are mainly recognized in the hornstone, and the feldspar is mainly albite and orthoclase, while the chlorite is mainly Mg rich chlorite and Fe rich chlorite. The skarn minerals such as garnet, diopside, wollastonite and vesuvianite are recognized in skarn, and the garnet is mainly andradite. Feldspar, quartz, mica, hornblende and chlorite are recognized in porphyry and porphyrite, among which chlorite is mainly Fe rich chlorite and mica is mainly muscovite. Among them, longwave chlorite and longwave muscovite can indicate the mineralizing center and hydrothermal center of porphyry- skarn- hornstone, and longwave garnet can effectively indicate the proximal position of skarn. The main minerals can be distinguished by the FMI of thermal infrared. The whole skarn is between 9470 nm and 11600 nm, the FMI values of garnet and diopside are the largest, the content of FMI is the highest, and the whole hornstone is between 8500 nm and 9000 nm. The FMI values of mica and chlorite are lower than those of skarn, and the whole FMI changes little in porphyry, which lies between 8500 nm and 9280 nm. In hornstone and porphyry, the Pos2200 of mica less than 2206 nm corresponds to the better Cu- Mo mineralization, and the Pos2200 of mica short- wave movement in the hornstone corresponds to the strong Cu- Mo mineralization, and the Pos2200 of mica in skarn is between 2209~2212 nm; Pos2250 of chlorite in skarn and porphyry indicates the occurrence of strong Cu- Mo mineralization, while the position of “T” absorption peak of garnet is more than 11500 nm, which generally corresponds to strong Cu mineralization. The research results of this paper prove that the shortwave- thermal infrared technique can provide effective technical support for deep exploration and prospecting of the Jiama porphyry- skarn- hornstone metallogenic system.

Abstract:In recent years, with the rapid development of multi- collector inductively coupled plasma- mass spectrometry (MC- ICP- MS), the analytical precision of potassium (K) isotopes has been greatly improved, which in turn has promoted their development as potential geochemical tracers in processes involving continental weathering, crust- mantle interaction, and so on. Until now, the cumbersome and time- consuming process of sample pretreatments and the poor analytical accuracy caused by argon hydrides interference are still the biggest obstacles to the wide application of K isotopes. After completely dissolving the samples with hydrochloric acid, nitric acid, and hydrofluoric acid, purification of K from major matrix was performed on a customized quartz ion exchange column packed with ~2. 7 mL of AG50W- X8 cation exchange resin (BioRad TM，200~400 mesh) using 0. 5 mol/L HNO3 as the eluent. This one- step procedure can effectively separate K from Li, Na, Ti, Mg, Mn, Al and Ca, except for Cr, in most of the geological samples. To find the appropriate method for high- precision stable K isotopic measurements, for minimizing the ArH+ yield and improving the stability of the instrument, three methods were compared here (the high- resolution mode, high- resolution mode with continuous acquisition measurement run mode, and the low- resolution mode with a method designed to eliminate ArH+ interference). The low- resolution mode has the advantages of low cost, high stability, and high precision (long- term precision at about 0. 08‰ for our laboratory). When used to measure the K isotopic composition of a series of international geological reference materials, the results are consistent with previous values within analytical precision, indicating the reliability of this method. The K isotopic composition of a set of Chinese national rock standard materials is determined here. The measured values of K isotopes can provide a reference for the data comparison between different laboratories in future.

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