Abstract:Xilinhot Block is located in the middle segment of the Xing- Meng Orogen in Inner Mongolia. Precambrian rocks in the block consists of Baoyintu Group and gneissic granite. Discovery of ~1.4 Ga Mesoproterozoic granitic rocks provides evidence for existence of the Xilinhot Block, but its petrogenesis and tectonic implication are still unclear. Mesoproterozoic granitic rocks in the Sonid Left Banner area consist mainly of yenogranite and monzogranite. And zircon LA- ICP- MS U- Pb dating for four samples yields ages of 1373±7 Ma and 1399±11 Ma, respectively, suggesting middle Mesoproterozoic in age. The gneissic granitoids are characterized by high SiO2 and alkali, with K2O/Na2O>1 and peraluminous, high total REE content with enrichment of LREE rather than HREE, and distinct negative Eu anomaly. All these features indicate that they belong to A2- type granite. The in- situ zircon Hf isotopic analysis shows depleted compositions with (176Hf/177Hf)i ratios varying from 0.281924 to 0.282288, εHf(t) values from +0.8 to +11 and two stage Hf model ages (TDM2) from 1.45 to 2.17 Ga. Generally depleted isotopic composition and whole rock εNd(t) of (+0.3~+1.0) except one sample with a value of -0.2 suggest that the gneissic granitoids were the product of partial melting of accretion crust in the end of the Paleoproterzoic (1.88~1.97 Ga). Regionally extensive occurrence of 1.4 Ga potassic granitoids displays occurrence of a tectonic- magmatic event triggered by crustal extension, which was response to breakup of Colombia supercontinent. 1.4 Ga A- type granitoids in the Xilinhot block indicate that the Xilinhot Block and North China Craton in the Mesoproterozoic both were in a tectonic setting of continental extension.

Abstract:The Zalantun region, located in the middle part of the Erlian- Hegenshan- Heihe suture belt, contains well- developed early Late- Paleozoic granitoids superimposed by ductile deformation. Through field investigation and systematic analyses, such as microscopy, geochemistry and zircon U- Pb geochronology, we investigated rock- forming chronological sequence, petrogenesis and tectonic setting of the granitoids, redefined the time of their deformation, and then further revealed amalgamation between Erguna- Xing’an and Songnen blocks, providing new materials for understanding the regional tectonic evolution of the Xing’an- Mongolian Orogenic Belt. Geochronological study shows that the early Late- Paleozoic magmatism in the Zalantun region happened during 405~325 Ma, and can be sub- divided into three periods: Stage I at the Early- Middle Devonian (405~380 Ma), stage II at the Late Devonian- initial Early Carboniferous (365~350 Ma) and stage III at the late Early Carboniferous (335~325 Ma) respectively. TheⅠ stage and Ⅱ stage granitoids belong to metaluminous to weakly peraluminous granitoids of shoshonite series and high- K calc- alkaline series, and are likely the I- type and high fractionated I- type granites formed in island- arc magmatism of subduction environment. And the Ⅲ stage ones belong to metaluminous to weakly peraluminous granitoids of middle to high- K calc- alkaline series, and are likely high fractionated I- type and A- type granites formed in magmatism of post- collisional environment. The universal deformation of the granitoids, which was the product of lateral escape in a post- collisional environment, occurred in the end of Late Carboniferous to Early Permian (308~290 Ma). We conclude, therefore, that the occurrences of the early Late- Paleozoic granitic magmatism in the northern Great Xing’an Range was related to the collision and combination between Erguna- Xing’an and Songnen blocks, and the amalgamation at the Zalantun region might occur in the middle Early Carboniferous.

Abstract:Diorite in the Bieruozecuo area of Tibetoccurs in the Early Cretaceous Qushenla Group or intermediate- felsic rocks as irregular or elliptic stocks, with minor mafic enclaves. LA- ICP- MS zircon U- Pb dating of the diorite yields a crystallization age of 81.4±0.9 Ma (MSWD=0.55), suggesting late Cretaceous age for magmatic activity. Geochemical analysis shows that the diorite is rich in K2O and poor in CaO, and should belong to quasi aluminum, high K and Ca, alkaline series rock (KCG). The total amount of rare earth elements ranges from 113.80×10-6 to 197.28×10-6, with (La/Yb)N of 11.98～20.26 and the δEu of 0.83 to 0.98. Chondrite normalized REE patterns show relative enrichment of LREE, right- dipping distribution trend, and no obvious Eu depletion. Primitive mantle normalization spider diagram reveals enrichment of K and Rb and depletion of Nb and P, and these features are similar to that of arc volcanic rocks. Geochemical compositions of the diorite show double features of mantle and newly- formed crust, indicating that the diorite likely resulted from linear thermal uplift and thinning decompression of the crust under the effect of mantle flow diaperism in the early stage of subduction and collision. The mantle thermal energy and materials, together with partial melting of the crust, resulted in the formation the diorite in the post collision- extension environment during the ocean- continent transition of the Bangonghu- Nujiang suture zone.

Abstract:The Haorigeshan pluton in Inner Mongolia is located at the junction between the northern margin of the North China and southern margin of the Central Asian Orogenic Belt. A systematic geochemical study can facilitate understanding the tectonic- magmatic evolution and geodynamics background of the belt from Late Paleozoic to Early Mesozoic. The Haorigeshan pluton consists mainly of monzogranite, which can be further divided into muscovitebiotite monzogranite and porphyritic biotite monzogranite. Zircon UPb dating yields weighted 206Pb/238U ages of 244.9±1.6 Ma and 230.2±1.5 Ma for them respectively, indicating that the Haorigeshan monzogranite formed in the EarlyMiddle Triassic. Geochemical results show that the Haorigeshan monzogranite has SiO2 of 72.58%~74.42%, K2O of 4.06%~5.82%, Na2O of 3.08%~3.88%, Al2O3 of 13.39%~14.55%, and A/CNK of 1.02~1.13, suggesting high- K calc- alkaline and peraluminous. Relatively low total REE, enrichment of LREE relative to HREE, negative Eu anomalies, high contents of Rb, U, Hf and low contents of Ba, Nb, Ta, Ti and Zr, all suggest that the Haorigeshan monzogranite is characteristic of high fractionated granite. Zircon Hf isotopic analysis displays that εHf(t) values are nearly negative and consistent with that Triassic granites in the northern margin of North China Craton, suggesting that the source region of Haorigeshan monzogranite is more close to the North China Craton. This study shows that the Haorigeshan monzogranite formed in the post- collision tectonic setting, which is closely related to the final closure of paleo- Asian ocean.

Abstract:Ningzhen ore cluster area, located in the eastern section of the Middle- Lower Yangtze River Reaches metallogenic belt, hosts a large amount of intermediate- felsic intrusive rocks related to copper and iron deposits. For example, the Anjishan granodiorite porphyry and Weigang granodioritethe in the study area are closely related to copper and iron deposits such as Anjishan copper deposit, Funiushan iron deposit. Many petrological studies have been conducted in the Ningzhen ore cluster area, but study on source characteristics of these granitic rocks is relatively poor. In this study, we conducted LA- ICP- MS zircon U- Pb dating and zircon Hf isotope analyses for samples from the Anjishan complex and Weigang complex, to determine diagenetic ages and discuss characteristics of the magmatic source and their relation with mineralization. Our zircon U- Pb dating yields diagenetic ages of 108.9~110.9 Ma and 107.3~109.6 Ma respectively for Anjishan granodiorite- porphyry and Weigang granodiorite, indicating the diagenetic age of late Mesozoic magmatic rocks in the Ningzhen ore cluster area should be 110~100 Ma, about 20 Ma later than that in other area of the Middle- Lower Yangtze River Reaches metallogenic belt. Hf isotope analyses show that the zircon εHf(t) value of the Weigang granodiorite ranges from -47.4 to -16.9 with a mean value -24.9, and the two- stage TDM2 Hf age ranges from 2.24 to 4.14 Ga, with an average of 2.73 Ga, suggesting that the Weigang granodiorite resulted from partial melting of the lower crust during the Mesoarchean to Paleoproterozoic. While zircon εHf(t) value of the Anjishan granodiorite porphyry ranges from -16.8 to -8.9 with a mean value of -12.4 and the two- stage TDM2 Hf age ranges from 1.74 to 2.23 Ga with a mean value of 1.96 Ga, suggesting that the Anjishan granodiorite porphyry was probably mixing of the materials from mantle and lower crust. This study, combined with previous results, concludes that the complex related to skarn- type iron deposit contains more crustal material than the complex related to skarn- type copper deposit. The ratio of material contents between crust and mantle in the source area of magma is likely an important factor controlling the mineralization of copper and iron in the MiddleLower Yangtze River Reaches metallogenic belt.

Abstract:Niutangjie large tungsten deposit locates in the south of the Miaoershan- Yuchengling batholith in Northern Guangxi. The ore bodies are closely associated with a slightly chloritized fine- to medium- grained granite. The whole- rock geochemical characteristics of this granite indicate that it is a peraluminous, highly fractionated and evolved, W- rich granite. Zircon in situ U- Pb dating of this granite yielded a diagenetic age of 410±4.9 Ma. The in situ U- Pb dating of apatite co- existed with scheelite in ores gave a metallogenic age of 418±37 Ma. The two ages indicate that both diagenesis and mineralization of the Niutangjie tungsten deposit occurred in the Caledonian period. This paper also carried out a systematic study on the ores of Niutangjie tungsten deposit. Firstly, according to the alteration types, three different types of ores were divided: skarntype ore, chloritized ore and quartz vein (lump)- type ore. Secondly, by the characteristics of these ores, three metallogenic stages were divided: skarnization stage, quartzsulfide stage and the late silication- carbonation stage. These three metallogenic stages are corresponding to the three different types of ores. Thirdly, thein situ trace element compositions of scheelite in each metallogenic stage were analyzed. According to the Mo contents and Eu anomalies in REE patterns of scheelite, the variation trend of the oxygen fugacity was constrained. By the changes of Na and Nb contents and the REE patterns of scheelite, the mechanisms of REE substituted into scheelite and the evolution of metallogenic fluid were revealed. Fourthly, the oxygen isotopic datum of scheelite reveal that the metallogenic fluid is magmatic water mixed with meteoric water. Fifthly, the W compositions of the parental granites indicate that the metallogenic materials of the Niutangjie tungsten deposit originates from the ore- forming parental rock. Thus, the Caledonian highly fractionated and evolved granites in this tungsten deposit are important sources of metallogenic materials.

Abstract:Ningwu basin, one of the most important mineral districts in the Middle and Lower reaches of the Yangtze River metallogenic belt, is characterized by the extensive development of Mesozoic volcanic rocks as well as iron ore deposits. With increasing of deep prospect in this area in recent years, finding ore deposits is increasingly difficult accompanied by increasing cost. It is high time to use geophysical methods to resolve deep geological structure, provide direct information for deep prospecting and reducing exploration risk. In order to understand the spatial distribution of deep structure, rocks and strata in the Zhonggu ore field in the south section of Ningwu Basin, this study carried out the inversion rese arch of deep geological structure and determined the distribution of strata and rocks through the regional gravitymagnetic data and and drilling geological information. Based on the combination modes of gravity- magnetic prospecting and geological factors of ore controlling, two favorable prospecting targets in the Zhonggu ore field have been determined through inversion results. And this will provide references for the next step of prospecting.

Abstract:In order to determine the formation time and provenance of the Xinxing Formation of Zhangguangcailing Group, this study carried out geochronological analyses on detrital zircons and magmatic zircons from the study area. Several groups of the concordant ages for two groups of detrital zircons from the Xinxing Formation were obtained in this study using LA- ICP- MS U- Pb dating method. The minimum peak (concordant) age for 91 points of sample BP18R15 is 260 Ma (41 points), while the minimum peak (concordant) age for 100 points of sample BP18R83 is 253 Ma (52 points). The minimum single point age was 192 Ma and 207 Ma. CL images show that most zircons are euhedral- subhedral in shape and present finescale oscillatory zoning, as well as high Th/U ratios, implying their magmatic origin. The study above suggests that the lower limit of the Xinxing Formation should be the late Permian. Combined with the age (210±1 Ma) of syenogranite intruding into the Xinxing Formation, this study believes that the Xinxing Formation of the Zhangguangcailing Group formed between late Permian and late Triassic, rather than the Neoproterozoic as previously believed. It can be concluded from the age frequency of detrital zircons from the Xinxing Formation that the sediments of the Xinxing Formation came mainly from the late Paleozoic geological bodies in surrounding areas, with minor from other geological bodies with time range from Mesoproterozoic, Neoproterozoic, and Early Paleozoic to Early Mesozoic. Existence of Precambrian detrital zircons implies that the Precambrian residual geological bodies might occur in regional surface or shallow crust during the deposition of the Xinxing Formation. Almost all of the sediments in the Xinxing Formation sourced from the SongnenZhangguangcailing massif, suggesting that the collage of Songnen- Zhangguangcai massif and Jiamusi- Xingkai massif and north China massif should occur later than the late Permian.

Abstract:The “Datangpo- type” manganese deposit in southeast Chongqing formed during the interglacial period between Marinoan ice age and Sturtian ice age. It is a multi- stage, polygenetic sedimentary rhodochrosite deposit formed in the graben- horst type continental margin sedimentary basin in the southeastern margin of the Yangtze block. The ore- forming period was obviously influenced by thermal events, such as tectonic activity, magmatic activity (volcanism) and “black smoke window”, and closely related to the mineralization of the rift basin caused by the Rodinia supercontinent breakup. There is a distinct coupling relationship among glacial transition, rift basin and manganese mineralization, which also presents typical features of sedimentary geochemistry. This study carried out detailed geochemical analyses on samples of Mn- bearing ores and surrounding rock samples from different mining areas and different occurrences in the study area. The geochemical diagrams indicate that oreforming material sourced from the deep area and mineralization was affected by hydrothermal fluids. In addition, the samples are enriched in As, Sb, Sr, Mo, Ag, Ba, Th, U and other hydrothermal fluid deposition markers. The average value of ΣREE in manganese ore is 159×10-6, distinctly higher that in normal deposits manganese ore (19×10-6). V/Cr, V/(V+Ni), Ce/La and lgCe/Ce* of Mnbearing ore samples indicate that manganese deposit formed in an anoxic environment and is enriched in Mo, U and other oxidation- reduction sensitive elements. The oxidationreduction condition of the manganeseforming basin controls the formation condition of manganese ore and the metallogenic process is a comprehensive result of the transformation of mineral phases in different stages of sedimentary, diagenetic and epigenetic stages. The formation of manganese ore deposit can be divided into three stages. The first stage was the enrichment of MnO2 sediments in the upper oxidation zone of the stratified sea water in the sedimentary period. The second stage was periodic short deposition process, during which MnO2 sediments were taken to the bottom of the basin by oxygenrich underflow. The third stage was the quasi syngeneticdiagenetic period, during which MnO2 is reduced to Mn2+ in an anoxic environment under the action of anaerobic bacteria or sulfate bacteria. At the same time, OH- generated increases alkalinities of seawater at the bottom and pore fluid of seabed sediments, forming primary manganese ore deposit and Mn- bearing carbonate sediments, which were further formed into manganese ore by the diagenesis.

Abstract:The Cenozoic carbonate rocks, which are distributed widely in the Pearl River Mouth Basin, were found to host the largest biogenic reef oil field on the sea in China and of important research value. Based on the Cenozoic tectonic evolution of the South China Sea and Cenozoic tectonic evolution of the Pearl River Mouth Basin, this paper presents the study of geological conditions of carbonate formation. The study found that the distribution of Cenozoic carbonate rocks in the South China Sea is closely related to the disappearance of the ancient South China Sea and the expansion of the New South China Sea, and the suitable window period for the development of carbonate rocks was the extension period of the New South China Sea, obviously controlled by the expansion of the New South China Sea. The two expansions of the New South China Sea in the Oligocene—Miocene were related to the Neo Tethys back arc spreading. The Pearl River Mouth basin developed two types of carbonate platform: the ancient uplift edge of carbonate platform and volcano uplift isolated carbonate platform. The distribution of ancient uplift or volcanic uplift, tectonic subsidence and the global sealevel fluctuation are the main controlling factors of carbonate rocks and reef development in the Pearl River Mouth Basin.

Abstract:Several medium to large gas fields have been discovered in the deep- water area of the Qiongdongnan Basin, but their accumulation mechanism and dynamic process are still in dispute and have constrain oil and gas exploration in this area. Through organic geochemical and structural geology methods this study analyzed and investigated the distribution of Yinggehai and Huangliu Formation reservoirs, gas maturity/origin and possible accumulation mechanisms in the central canyon gas fields. Geochemical and geological results show that natural gases are mainly derived from type III kerogens, and their possible source rocks are the prodelta and neritic mudstones of Yacheng Formation in Ledong- Lingshui sag. Extensive distribution of turbidite channels of Yinggehai and Huangliu formations, accumulation and cap assemblages and pressure features effectively control multiple sequential charging process and accumulation- escape balance, with local structure highs controlling the scale of the gas pool. Anomalous high- pressure in the deep part of Ledong and Lingshui sags provides adequate driving force and migration channels for large accumulation, and the vertical pressure compartment and regional cap rock have controlled the sequences for gas accumulation. The natural gas accumulation in the central canyon is characteristic of vertical- lateral migration and composite accumulation of average pressure and excess pressure zone. Strong structural deformation is favorable for rapid releasing of pressure and fluids. Diapir uplifting and canyon incision shows a mirror- like relationship, resulting in a big remnant pressure gradient and thus forming high efficient migration pathways. Based on this new accumulation model, this study proposes that the structural traps of the Meishan Formation below the central canyon, the traps in the Lingnanslope and the low uplift of Songnan could be new exploration targets for large to medium gas fields in the deep- water area.

Abstract:This study performed the analyses of the contents of the major, rare earth and trace elements and mineral compositions of the Heidaigou Openpit Coal Mine. The results show that the average REE content of the Heidaigou coal mine is 248.12×10-6, about 2.83 times the average value of all the coal mines in China. The average contents of LREE and HREE are 236.66×10-6 and 11.46×10-6, respectively, with an average LREE/HREE value of 20.81 and (La/Yb)N of 1.59, indicating that LREE in coal is relatively enriched relative to HREE. Part of rare earth elements in coal may be enriched in aluminosilicate and clay minerals. REE distribution patterns show the δCeS ranges of 0.89 to 2.21 and moderate δEuS loss of 0.46~0.86, verifying the stability of sedimentary environment played an important role in input of REEs to coal during the formation and evolution of coal seams. The content of trace elements (such as Ga, Pb, Se, Sr, Th and Zr) in the Heidaigou Coal Mine is obviously higher than that in China, North China Paleozoic and North America, and is higher than the crust Clarke value.