Abstract:Mid-Late Neoproterozoic to Early Paleozoic volcanism in the Qilian Mountain area, which shows systematic variations in space and time, seems to have been the volcanic response to the tectonic evolution of the Qilian Mountain. The volcanism gradually changed from rift-related and continental flood basaltic through MORB-type and island-arc and back-arc to post collisional rift-related eruptions along with the tectonic evolution of the Qilian Mountain shifting from rifting and break up of Rodinia through opening and spreading of the Early Paleozoic oceans, subduction of the oceanic slabs and back-arc extension and ocean closure to arc-continent and continent-continent collision. The continental rift-related and flood lavas with ages of 850-604 Ma are distributed mainly on the Qilian and Qaidam Blocks. The widespread MORB-type and "island-arc-backarc"-type lavas were generated from about 550 to 446 Ma in both the North Qilian and the South Qilian ocean-trench-arc-basin systems. In the meantime, the intracontinental rift related volcanism occurred in the central Qilian Block between about 522 and 442 Ma. The Early Paleozoic oceanic basins were closed at the end of Ordovician (about 446 Ma). Subsequent post-collisional volcanism occurred on the northern margin of the Qilian Block from about 445 to 428 Ma. Such spatial-temporal variations provide important constraints on the geodynamic processes that evolved at the depth to form the Qilian Mountain. These processes involved (1) upwelling of mantle plumes or a mantle superplume and subsequent rifting and break- up of Rodinia and subsequent opening, spreading and subduction of Early Paleozoic oceans followed by island-arc formation, (2) roll-back of the subducted oceanic slabs followed by back-arc extension and back-arc basin formation, (3) ocean closure and slab break- off followed by upwelling of asthenosphere and post-collisional volcanism. Intensive orogenic activities occurred in the Late Silurian and Early Devonian (about 420 to about 400 Ma) in response to the exhumation of the subducted crustal materials. Mountain collapse and lithosphere extension happened and formed post-collisional granitic intrusions at <400 Ma.

Abstract:Conodont fossils were found for the first time in the Late Permian Labuchari Formation in the Tanggula Range. The conodonts include Hindeodus typicalis, H. eurypyge and H. praeparvus. According to their significance and the investigation of sequence stratigraphy and sea-level changes, the Permian/Triassic boundary may be determined between the top of 29 and the bottom of 30 of the measured section. Here, the carbonatite ⁸⁷Sr/⁸⁶Sr ratios of Labuchari Formation were determined. At the Permian/Triassic boundary, ⁸⁷Sr/⁸⁶ Sr ratios are from 0.707017 to 0.707032, which are significantly lower than those in other areas. The main reasons for the remarkable difference might be the existence of extensive volcanic activities in Tangula Range at the Permian/Triassic boundary and the basalt eruptions in Yangtze region during the late Permian. In addition, the comparison between the strontium isotope curve and sea-level curve shows that the minimum ⁸⁷Sr/⁸⁶Sr ratio has a good consistency with the data of the first flooding surface, suggesting that global sea level change was the main factors controlling the strontium isotope.

Abstract:Amphibolite is distributed sporadically in Paxialayidang area on the southern margin of Altun terrain. The amphibolite is ellipsoidal or lenticular in shape and is wrapped by marble of Altun terrain. In this paper, the authors studied petrology,geochronology and geochemistry of the amphibolites. LA-ICPMS zircon U-Pb dating yielded ages of (432.5±5) Ma and (857.4±7.1) Ma for metamorphic event and protolith respectively, and shows that the protolith was formed during Neoproterozoic Qingbaikou period. Amphibolite is slightly enriched in REE, and shows unnoticeable fractionation between light rare earth elements (LREE) and heavy rare earth elements (LREE) and the signatures of subduction zone basalt. The primary magma originated from an enriched mantle source, which was formed by the recirculation of subducted slab, and was modified by fluid or melt subsequently. Combined with the evolution of regional tectonic, the authors hold that the protolith of amphibolite was formed in an incipient continental rift and was a transitional type formed during the transition from continental extension to continental rift. The younger age of (432.5±5) Ma represents the time of metamorphic event, which was caused by the detachment of continental lower crust during Early Silurian. In this paper, the authors provide new geochronological and geochemical evidence about basic magmatic activity during middle-late stage of Neoproterozoicin on the southern margin of Altun terrain. The basic magmatic activity was the response to the Rodinia supercontinent breakup on the southern margin of Altun terrain.

Abstract:The Reshui Mo polymetallic deposit is located at the North Kunlun magmatic arc, where lots of intrusive rocks occur. Geochemical data reveal that the porphyroid biotite monzogranite from East Kunlun is rich in silicon (67.64% -71.09%), Al₂O₃ (13.8%-14.57%),Na₂O(2.23%-3.02%),and K₂O(3.95%-5.18%),with ratios of K₂O/Na₂O being 1.35-2.32 and A/CNK being 0.86 -1.11,1.01 on average, suggesting that the granite should belong to high potassic calc-alkaline and I type granite. The porphyroid biotite monzogranite is intensively depleted in HFSE (Ta, Nb, mCe), enriched in LILE (Rb, Th, U, K, Pb), and poor in P, Ti. The total rare earth elements (Σ REE) are 94.27×10^-6-127.44×10^-6, with an average of 110.92×10^-6. The rare earth element distribution curve shows the right-inclined type, and has characteristics of obvious enrichment of light rare earth and depletion of heavy rare earth elements. LA-ICP-MS zircon U-Pb dating shows that the formation age of the rock is (230.9±1.4) Ma, belonging to Indosinian stage. The molybdenum polymetallic deposit is closely related to the magmatic activity during this period. Based on tectonic history and the structure environment in combination with the geochemical characteristics, the authors hold that the porphyritic biotite monzonitic granite of the Reshui deposit was formed at the structural transformation stage, and Rershui area has potential for finding porphyry deposits.

Abstract:The ophiolite in northeast Jiangxi is one of rare Precambrian ophiolites in Jiangnan orogenic belt and also a hot topic for the tectonics of South China. The mantle peridotite mainly consists of harzburgite. Compared with primitive mantle, the peridotites have lower total REE values varying from 0.83×10^-6 to 2.62×10^-6 and higher MgO content. On the chondrite-normalized REE patterns, the rocks display enriched LREE patterns. When normalized to primitive mantle, all samples show variable enrichment of LILEs and are characterized by significant Nb negative anomalies. These features imply a depleted mantle source, which was overlapped by fluid alteration in a subduction zone. On the HREE patterns, the calculation shows that the harzburgites exhibit the residues of 10%-30% partial melting of the mantle source. Meanwhile, the spinels from mantle peridotites in northeast Jiangxi can be divided into two types which are Cr^#>60 and Cr^#<60 in the light of their chemical compositions. It is thus concluded that the spinels are of characteristics of both MOR and SSZ setting. In combination with previous researches, the authors infer that ophiolites in northeast Jiangxi originated in a MOR setting at ca. 1060 Ma, and was modified by melts and fluids in a SSZ mantle wedge at ca. 970 Ma.

Abstract:The Doroji granite is located in the southern part of the Da Hinggan Mountains, lying in a polymetallic ore-forming zone (Au-Ag-Cu-Zn-Sn-Fe) of the Da Hinggan Mountains. There are various kinds of magmatic rocks in this area, with multiple metallogenic elements, and Doroji granite is one of the biggest plutons, with an exposed area of about 190 km². To clarify the source of the Doroji granite and the relationship with the mineralization, the authors conducted a systematic study of the mineralogy and Hfisotopic compositions. Doroji granite is dominated by monzonitic granite and syenogranite. The monzonitic granite is composed of plagioclase (32%), K-feldspar (45%), quartz (20%), with miner biotite, muscovite, amphibole and pyroxene (3%). The syenogranite consists of quartz (10%-15%), K-feldspar (60%-70%), plagioclase (30%) with minor biotite (about 5%). Perthites is well developed in the monzonitic granite and syenogranite. Biotites are mainly ferribiotite and siderophyllite. Amphiboles are mainly kaersutite and hornblende. Pyroxenes are augites. The mineralogy indicates that the Doroji granite belongs to I-type. The ε_Hf values of monzonitic granite range from -1.6 to 17.6, and the ε_Hf values of syenogranite range from -3.3 to 12.2. Hf isotopic compositions of the Doroji granite indicates that the source was the juvenile crust, resulting from the remelting of the depleted basaltic rocks.

Abstract:This paper has summarized the theory, methods and practices of clastic sedimentary rocks and sediments for chemically geodynamics. Clastic sedimentary rocks/sediments can record their provenances effectively. Nd isotopic compositions and U-Pb dating as well as Hf isotopic compositions of zircons in clastic sedimentary rocks/sediments are critical approaches to decipher provenances of clastic materials, interactions between the crust and the mantle, different blocks of their derived regions, and formation and evolution history of provenance's regional crust. Nd model age of a bulk sample indicates an average extraction time of its derived regional crust from the depleted mantle as a whole. Hf model age of a zircon grain shows its source characteristics during its formation. The chemistry of fine-grained clastic sedimentary rocks/sediments represent average compositions of their derived regional upper crust for most insoluble elements during weathering, transportation, and deposition in water, such as Nb, Ta, Th, Sc, Zr, Hf, Sc,Ti and REE. The authors' practice shows that the formation and evolution histories of the North China Plate, the Yangtze Plate, and the Central Asian Orogen represented by the Da Hinggan Mountains are significantly different from each other. Crustal growth occurred predominantly in Neoproterozoic-Paleozoic periods in the Da Hinggan Mountains. During chemically geodynamic analysis of clastic sedimentary rocks/sediments, such factors as complexity of geological processes and combination between micro- and macro-scales as well as between locality and integrity should be considered systematically.

Abstract:As the largest Mesozoic-Cenozoic basin in the Tibetan Plateau, the Qiangtang Basin is the key area to reveal the evolution of Tethys, and hence its structure and evolution have aroused much interest. However, for a long time the problems concerning the existence or nonexistence of the pre-Cambrian basement in the Qiangtang Basin and its tectonic evolution have been topics of much controversy. Yanshiping Group is the most widely distributed strata which have the most complete set of Jurassic in the Qiangtang Basin,and its detrital sediments contain a lot of important information concerning the tectonic evolution of the Qiangtang Basin. The authors hence selected the sandstone from Yanshiping Group in the east of the Qiangtang Basin, the northern foot of the Tanggula Range in the Wenquan region to perform LA-ICP-MS U-Pb dating so as to provide an important basis for solving tectonic evolution about the basement in the Qiangtang basin. The ages of 429 valid test points from 8 sandstone samples show that the formation of detrital zircons from Yanshiping Group spanned a long period, and the ages of zircons range from New Archean to Late Middle Jurassic (2668-166 Ma), which have evident stage characteristics and can be divided into ten age groups. In combination with regional geology, the authors discussed and analyzed detrital zircon whose ages are greater than 486 Ma. It is held that the Qiangtang Basin has Pre-Cambrian basement, the main period of its formation is approximately 1974-1666 Ma, and the Pre-Cambrian basement also suffered from the post-tectonic reformation, and experienced the tectonic thermal events of the Columbia and Rodinia supercontinent, Greenville-Jinning tectonic movement of magma, Pan-African movement and a series of tectonic evolution. The results obtained by the authors support the opinion that the Qiangtang terrane belongs to the Gondwana.

Abstract:Early Jurassic Quemo Co Formation is very important for studying the sedimentary evolution form the late Triassic to the early Jurassic in Qiangtang basin. Geochemistry and provenance characteristics of sandstones in the Quemo Co Formation of Woruo Mmountain area were studied by analyzing the selected major element and trace element compositions. The results suggest that the sandstone deposited in the chasmic stage of the passive continental margin. The sandstones are the lithic sandstone which mainly consist of K-feldspar,plagioclase,illite, chlorite and quartz. The chemical index of weathering (CIW), the chemical index of alteration (CIA) parameters and the A-CN-K plot of the sandstones suggest that weathering of the elastic constituents has been intense in the area,the elastic constituents of sandstones underwent K-metasomatisim during weathering processes,illite replaced feldspar and perhaps the original kaolinite in the feldspar. The index of compositional variability (ICV) suggests that some sandstones contain first cycle materials The A-CN-K diagram indicates that a high average plagioclase-to-K-feldspar ratio in the provenance,varying from granodiorite to granite. The REE characteristics suggest only one source of acid igneous rock for the sandstones in this area.

Abstract:Apatite fission track analysis provides the opportunity for revealing differential uplift processes and uplift rate during the Mesozoic-Cenozoic on the northeast margin (Fugu-Wubao section of Jinxi flexural fold zone) of Ordos Basin, and offers new constraints and knowledge to the whole basin tectonic evolution history and the relationship between tectonic evolution and the coupling coexistence of multiple energy resources. The AFT age of different tectonic units and their different strata reveal that the uplift of Fugu-Xingxian area along the northern section of the study area was earlier during 86-56 Ma in the late Cretaceous and 44-37 Ma in Paleogene with the rate of speed being 24.5 m/Ma and 41.8 m/Ma. The uplift of Zijinshan area of the middle section of the study area was relatively late, and the key tectonic events took place at 68-56 Ma and 35 Ma during the late Cretaceous to middle-late Paleogene, with the rate of speed being 48.8m/Ma and 49.2 m/Ma respectively. The uplift of Linxian-Wubao area along the south section of the study area was during 35-21 Ma with the rate of speed being 73.9 m/Ma. Therefore, the north section uplifted early, the middle section uplifted relatively late, and the south section uplifted last. What is more, the overall tectonic activation period mainly happened late in Paleogene in Fugu-Wubao section of Jinxi flexural fold zone, and the tectonic uplift rate weakened gradually from the south to the north in the northeast of Ordos Basin. Additionally, the relationship analysis of the tectonic event and the mineralizing chronology revealed that the key structural events and moderate uplift speed controlled reservoir formation time or mineralization time of the coupling coexistence of multiple energy resources on the northeast margin of Ordos Basin, and show the collaborative and coupled relationship between the tectonic events and accumulations.

Abstract:There are considerable differences of the Tianshan metallogenic belt between China and Kyrgyz in such aspects as metallogenic epoch, mineral type and deposit size. As their metallogenic conditions are similar, due attention should be paid to the problem whether the differences are caused by preservation conditions or not. Apatite fission track analysis of Kyrgyz Northern Tianshan and thermal history modeling were performed, and the result shows that there existed four uplifting events from the Mesozoic to Cenozoic, from late Jurassic to late Cretaceous, Eocene and Oligocene, respectively. The late Jurassic uplifting happened in Terskey Range located in the south of Issyk-Kul Lake; the Eocene uplifting happened in Terskey Range and Kungey Range located in the north of Issyk-Kul Lake; the late Cretaceous Issyk-Kul Lake and Oligocene uplifting happened in Kyrgyz Northern Tianshan. By comparing uplifting history of Kyrgyz Northern Tianshan with that of China's Western Tianshan, it is shown that China's Western Tianshan uplifted earlier and lasted for a long time; the extent of exhumation exceeded that of Kyrgyz Northern Tianshan. Maybe it is the reason of the significant differences of mineralization between China and Kyrgyz Tianshan.

Abstract:Huangzhuang-Gaoliying fault is a relatively large buried active fault across Beijing urban area. It is the tectonic belt of Beijing depression and Xishan uplift. The study area is located in the Future Science and Technology City in Changping. In this paper, the authors analyzed the structure and activity of the fault with the methods of shallow seismic exploration, high density resistivity method and trench profile. The results show that Huangzhuang-Gaoliyang fault is a fault zone that consists of the major fault and secondary faults. The fault belt in bedrock is mainly manifested as step fault and extends up to Quaternary, being a "Y" fault combination. Research shows that this fault has been strongly active since Holocene. Thus, the combination of three methods of shallow seismic exploration, high-density electrical and trenches is significant for detecting the buried fault in the city and exploring its activity, and it is also very important in applying practical assessment to reducing urban seismic hazard.

Abstract:The Sudeerte tectonic belt is one of the most important hydrocarbon accumulations in Beier depression of Hailar basin. From the detailed structural geometry and kinematics analysis of Sudeerte tectonic belt and peripheral Beixi subdepression and Beizhong subdepression using balanced section technique and herringbone truss method based on inclined shear model, the authors detected that the special structure style was caused by a series of extensions:the direction of extension in Nantun Formation was nearly NW-striking, forming an EW-trending rift basin group, then the direction changed to northwest in a short period of early Damoguaihe Formation stretching and continued thermal depression to the present. The boundary faults in the east of Beizhong subdepression were the major boundary faults of Beier depression in the extension of early Damoguaihe Formation, and show a ramp-flat listric feature. Sudeerte tectonic belt is "roll-over anticline" formed in the upper part of the first fault floor due to the combined effect of gravity and geometry of boundary fault. It is thus held that the mechanism of anticline type of Sudeerte tectonic belt is bending fold rather than buckle fold.

Abstract:Located in eastern Heilongjiang Province, the Dasanjiang basin group has experienced multiphase tectonic movement since Mesozoic, and formed a dozen of separated residual basins. Due to the lack of key evidence, there exists controversy concerning existence or nonexistence of a unified basin in Dasanjiang area during the early Cretaceous. The field geological survey and drilling core observation show that the basin lacks marginal facies, and is dominated by the delta plain subfacies and shore shallow lake subfacies. Paleocurrent recovery and heavy mineral characteristics show that the study area mainly has three major provenances existent respectively in the west and northwest, east and southeast, concentrated from the periphery to the center in space. The seismic reflection characteristics show that the lower Cretaceous strata have typical faulted-depression composite structure, and at the same time, the strata of the basin did not show obvious thinning from the center to the edge during the depression period. So the boundary faults of the basin mostly should be thrust faults which reformed the basin in later period. All the evidence strongly support the argument that the Dasanjiang area was a unified basin in the early Cretaceous. The results obtained by the authors provide an important basis for the restoration of prototype basin of Dasanjiang basin group and also offer a reference for the oil and gas resources substitution and exploration in Northeast China.

Abstract:Corresponding relationship between geochemical characteristics and depositional environments was established through analyzing distribution of mudstone, content and indexes of the trace and rare earth elements from the Liangshan Formation, Lower Permian, Dushan area, southern Guzhou. The results show that the gross amount of REE (ΣREE) varies from 127.23×10^-6 to 450.07×10^-6 with an average of 271.09×10^-6, which is obviously higher than the gross amount of American shale REE. And the ratio of LREE/HREE is usually between 7.66 and 15.67 with an average of 9.51, which indicates enrichment of LREE. Relevance between Ce anomalies and Eu anomalies, Dy_n/Sm_n ratios, and bulk REE show that diagenesis had some effects on REE of the Liangshan Formation during the depositional transformation period, and it seems that abnormal values of Ce anomalies are not a reliable redox indicator. An oxygen and oxygen-depleted seawater environment was judged through trace element ratio indexes, such as Ni/Co≈0.20, U/Th≈0.2, V/Cr≈1.09, δ U≈0.73, V/Sc≈7.43; in addition, abundant development of benthos can be a strong evidence. The authors argue that the seawater environment of sedimentary period during the Liangshan Formation was an evolution process with dynamic transformation, rather than a pure oxygenate, low oxygen or reducing environment. More specifically, the initial seawater environment represented oxygenate condition for biological reproduction, then gradually evolved into low oxygen or even reducing environment which hindered degradation of organic matter. The authors put forward two possible cases:(1) Deposition flux of high organic-matter under humid climate and rapid accumulation of shallow-water deposit used much oxygen of bottom water, which resulted in a transformation from oxygenate to low oxygen until the reducing environment;(2) The water interface overlapped or fluctuated near the oxygenate to low oxygen interface of the Liangshan Formation, and the oxygenate to low oxygen interface rose gradually with continuous transgressive process, then a low oxygen environment appeared with the death of early organisms, and oxygen exchange between deposits and water became less and finally transferred into a reducing environment.

Abstract:Using the latest seismic data of 300 km² depth migration before stack in Lungudong, the authors identified three stages and four groups of fractures in Lungudong gas field by various means. The strike and compactness of the fractures are controlled by faults. The fractures are mainly high angle(45°-75°)narrow fractures. Corrosion is developed along the fractures, and the dominant strike is NE-SW. In the longitudinal field, the fractures of Yijianfang Formation has maximum density(14 fractures per 100 m), followed by the compactness of the fractures of Yingshan Formation (6 fractures per 100 m) and the compactness of the fractures of Lianglitage Formation (4 fractures per 100 m). In the plane field, fracture is mainly distributed in the area within 1 km of the main faults. With the increasing distance from the fault, the degree of fracture development (linear density of fractures) decreases with the tendency of index number. On such a basis, the authors have comprehensively considered developmental characteristics of main fractures and accompanying fractures. In the plane field, crushed zones of Lungudong fault are divided into pinnate crushed zone, transform crushed zone, echelon crushed zone,and composite crushed zone. The area of pinnate crushed zones is the largest and most gas and oil spots are concentrated here, and high-efficiency wells are centrally distributed in this area at present. The exploration drill holes around the pinnate crushed zone offer a new train of thought for the study of strike slip fault controlling oil and gas reservoir and finding new rich domains of gas and oil.

Abstract:So far, both oil and gas found in Qaidam Basin are distributed around the Jurassic, Tertiary and Quaternary hydrocarbonrich sub-sag areas. In recent years, surrounding hydrocarbon-rich depression in petroleum exploration, Kunbei and Yingdong, the two "hundred million tons grade" oilfields,"hundred billion cubic meters" gas in the eastern front part of Altun Mountain and "hundred million tons grade" tight oil in Zhahaquan exploration area have been discovered, and the exploration has made great success. Along with the construction of ten million tons of plateau oil and gas fields in Qaidam Basin and the urgent need of finding new fields and new exploration areas and with the aid of major science and technology projects of Petro China, the authors used the data of boron element and clay minerals and employed Couch formula to carry out paleosalinity recovery, and finally confirmed that the Cenozoic sediment is salty lake deposition in Qaidam Basin. Comparing the Cenozoic salty characteristics of Qaidam basin with those of known hydrocarbon-rich depression in combination with organic geochemical test data of Yiliping depression, the authors hold that Yiliping depression is a potential hydrocarbon generation depression and is probably a new hydrocarbon-rich one. The oil and gas exploration surrounding the depression will be a new successive field and should have important strategic significance in oil and gas exploration in Qaidam Basin.

Abstract:The characteristics of lithology and lithofacies in Chang 7 tight oil in Heshui area, Ordos Basin, were studied by such means as core observation, traditional thin section analysis, conventional logging and imaging logging processing, combined with general physical analysis. Chang 7 tight oil reservoir is mainly sandstone caused jointly by sandy debris flow, turbidity current and slump, and source rocks are mainly mudstone and oil shale. According to grain size parameters, Chang 7 tight oil is further divided into six kinds of lithology and lithofacies, i.e., fine sandstone of sandy debris flow, fine sandstone of turbidity current, siltstone of turbidity current, fluxoturbidite, mudstone of semi-deep water or deep water and oil shale. According to conventional logging and imaging logging scaled by core data, the authors established the evaluation criteria of well logging identification in different kinds of lithology and lithofacies, realized the identification and classification of lithology and lithofacies in a single well on the longitude, and further explored the relationship between different kinds of lithology and lithofacies and TOC content as well as brittleness index. Finally oil-gas testing data and oil-gas interpretation results were combined to illuminate the quantitative control of lithology and lithofacies on physical property and oil-gas possibility of tight oil reservoir. The study of lithology and lithofacies of tight oil can lay the foundation for the further analysis of lithogenous phase and pore structure as well as the prediction of high quality reservoir. It can also provide theoretical guidance and technical support for the comprehensive assessment of Chang 7 tight oil and the prediction of favorable zones for oil-gas reservoir development.

Abstract:The newly discovered Baiganhu W-Sn ore district in Qimantag of East Kunlun orogenic belt provides a key window to insight into the W-Sn mineralization in Northwest China. In this paper, the authors present results from the ⁴⁰Ar/³⁹Ar dating of two muscovite samples collected from the ore-bearing quartz veins in the Baiganhu W-Sn ore district, which yielded two ⁴⁰Ar/³⁹Ar plateau ages of 422.7 ±4.5 Ma and 421.8 ±2.7 Ma, respectively. These two samples also yielded consistent (within errors) isochronal and inverse isochronal ages of 424 ±15 Ma and 418 ±24 Ma, respectively, suggesting that the analytical results are reliable. The new plateau ages show that the mineralization occurred in the Late Silurian, associated with the tectonic-thermal events induced by the closure of Proto-Tethys. The post-subduction continental collision caused the formation of granitic magmas sourced from remelting of the metalliferous metamorphosed Proterozoic sediments. The W-Sn mineralization resulted by the hydrothermal fluids exsolved from the granitic magmas during their upward emplacement.

Abstract:The Yuangezhuang pluton lies in Muping block, Yantai, Shandong Province. It is a typical granitic complex of Weideshan Late Yanshanian super-unit in Jiaodong. In this study, direct Re-Os dating of molybdenites collected from the granitoids was carried out, and the major elements and trace elements in whole rock samples were also analyzed. The results show that the pluton probably belongs to a kind of granite derived from mantle-crust and is characterized by high potassium and alkali as well as metaluminous to peraluminous nature. Besides, the isochron age is 117.8±5.7 Ma, with a weighted average of 118.27±0.70 Ma, similar to data of the metallogenetic epoch and characteristics of the host rock from many known Cu-Mo deposits in Late Yanshanian period. This suggests that it probably has a good prospect for molybdenum polymetallic mineralization.

Abstract:The Gonghudong is a typical skarn copper deposit in central Inner Mongolia. It is located in Mesoproterozoic Bayan Obo rift zone along the middle section of the northern margin of North China plate, and is hosted in the skarn belt formed by the contact of granite porphyry and crystalline limestone of Hujiertu Group. The Cu orebodies are lentoid and stratiform-like in shape. The metallic minerals mainly are chalcopyrite, bornite, sphalerite, chalcocite, pyrite and pyrrhotine, and the nonmetallic minerals mainly are garnet, diopside, calcite and fluorite. The LA-ICP-MS zircon U-Pb dating of granite porphyry yielded an age of (299.6±1.7) Ma, and thus the Gonghudong deposit was the product of Late Paleozoic tectonic magmatic activity. The granite porphyry has high Si, low Al, depleted Ba, Sr, P, Ti, with "V" type REE pattern, and the values of 10000Ga/Al and FeO^T/MgO range from 2.32 to 3.49 and 9.86 to 12.27, respectively. These data indicate that the granite porphyry belongs to A1 subtype of A-type granites and was formed in a post-orogenic extension environment.δ¹³C_V-PDB andδ¹⁸O_V-SMOW of the hydrothermal calcite are from -10.6‰ to -8.6‰ and from 4.6‰ to 24.67‰, respectively, suggesting that the CO₂ was supplied by the interaction of granite porphyry and limestone. Theδ³⁴S values of the sulfide range from 1.2‰ to 10‰, indicating that the sulfur was derived from the magma sulfur and marine sulfate. ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb of the ores are 17.847 to l8.173, 15.586 to 15.873 and 37.997 to 38.905, respectively. The Pb-isotopic compositions suggest that the ore-forming material was probably derived mainly from the granite porphyry.

Abstract:There are many Yanshanian acid intrusive bodies located in the northeast structural-magmatic belt of Taihang Mountain. The currently discovered polymetallic deposits and precious metal ore deposits are genetically related to the acid rocks of Yanshanian epoch. This study provides the metallogenic age of the Gaojiazhuang polymetallic deposit by means of Rb-Sr isotopic dating. The deposit is located on the northwestern margin of the Dahenan rock mass. Isochron age of (144.5±1.4)Ma is close to the formation age of Dahenan rock mass shown by zircon (U-Pb). Initial Sr isotope ratios (0.7122-0.7123), suggesting that the ore materials of the deposit were derived from the rock mass mainly formed by partial melting magma of crust-derived materials. It is shown that the evolution of Dahenan rock mass controlled the formation of polymetallic deposits in the study area. The metallogenic age of the Gaojiazhuang polymetallic deposit is consistent with the age of the second large-scale mineralization epoch in eastern China, with the geodynamic setting belonging to the tectonic regime transition period. In this unique metallogenic background, the emplacement of granitic magma took place along the intersection of NNE-striking and EW-trending faults. This process provided the necessary heat, fluid, volatile components and metallogenic elements for large-scale metallogeny.

Abstract:The Xinshuijing U-Th deposit in the Longshoushan metallogenic belt of Gansu Province is a typical alkali metasomatic U-Th deposit hosted in albitite. The ore-forming processes can be divided into three major mineralization stages, i.e., Nametasomatism, U-Th mineralization and post-ore stage. In this paper, the authors systematically analyzed major and trace elements in less-altered granite, albitite and ore of the Xinshuijing deposit, and discussed the element transportation using the isocon diagram proposed by Grant. During the Na-metasomatism stage, Na, Ca, Sc, V, Cr, Co, Ni, U, Th and CO₂, H₂O were enriched, while large ion lithophile elements and some of the light rare earth elements were depleted. The ore-forming fluids of the U-Th mineralization stage were rich in heavy rare earth elements, U, Th, PO₄^3-, with volatile components (CO₂, H₂O, F, etc) abundantly escaped. Combined with former studies, the authors hold that the ore-forming fluid was the mixture between the mantle fluid and meteoric water. Vapor escape and the oxygen fugacity decrease seem to have been the major mineralization mechanism, which induced coprecipitation of U-Th minerals and apatite. Th transported in the form of compound phosphate was further precipitated after apatite formation.

Abstract:Located along Kahama Archean greenstone belt around Victoria Lake area in Tanzania, the Mwamola gold deposit is a concealed large iron formation (BIF) type gold deposit closely related to the banded iron formation. The establishment of an oreprospecting model is very important in the search for the same type of deposits. The Mwamola gold deposit is the representative one among many gold deposits in the Archean Kahama greenstone belt of Tanzania. Orebodies are commonly stratiform and stratoid in form, controlled jointly by shear zone and strata, and mineralization is confined to the banded iron formation stratigraphic and lithologic units. The △T negative anomalies of ground high-precision magnetic survey can be used as a geophysical prospecting indicator because they can accurately identify ore-controlling strata (banded iron formation) or ore-bearing faults. The induced polarization depth measurement shows that "low resistance and high polarization" anomaly characteristics can serve as an indicator for the spatial orientation of the banded iron formation and gold orebody. The rock geochemical survey shows that Au,As,Sb have the feature of strong enrichment, and Au and As,Sb have significant correlation. Combined with geological, geophysical,geochemical prospecting information, the authors built a model of the Mwamola gold deposit, and establiehed a set of optimum combination prospecting methods and processes. The results obtained by the authors can play a certain guiding role in the exploration and evaluation of the greenstone belt banded iron form (BIF) type gold deposits.

Abstract:The geochemical behavior of heavy metal elements in soil is a hot research topic. Studies show that the geochemical behavior of heavy metal elements is related not only to soil texture, but also to the physical and chemical properties of soil. In this paper, the authors chose the farmland of Hebei plain as the study area, collected 325 soil samples, made effective state analysis of soil Pb, Hg heavy metals, and discussed the factors affecting the geochemical behavior of heavy metals. Some conclusions have been reached:(1) Pb, Hg water soluble ions and exchanged values show a significant negative correlation with soil pH values, and soil acidification results in increase of Pb, Hg effective fraction, which leads directly to increase of Pb, Hg in the crops; and hence maintaining soil pH in weak acid and weak alkaline range and preventing soil acidification and salinization can reduce the harm of heavy metals. (2) The values of organic matter and Pb, Hg exhibit significant positive correlation in soil, the increase of the soil organic matter can significantly reduce water soluble and exchangeable content of Pb, Hg elements. (3) With the increase of clay soil, Pb, Hg in water solution state and ion exchangeable state decrease, indicating that the clay can absorb a certain amount of heavy metal ions, and heavy metal elements Pb and Hg show certain relationship in geochemical behavior. The pH value, organic matter, and viscosity of soil seem to be important factors controlling the geochemical behavior of the heavy metals Pb, Hg.

Abstract:The hydrothermal activity area of Tibet is located in the key area of Indian-Eurasia collision orogenic belt, belonging to the Mediterranean-Himalayan tropical and rich in hot water resources. As one of the important window to study geological tectonic evolution, geothermal system properties, and climate change, the hydrothermal activity area of Tibet has been one of the key scientific problems in the field of geology. Based on 336 water chemical data of hot springs and using a variety of geochemical geothermometers, the authors evaluated thermal reservoir temperature, inferred the spatial distribution of geothermal anomaly, and explored its geological environmental effect. The results show that the hot water temperature ranging from 10.12℃ to 97.64℃ and higher than 60℃ accounted for 38.9% of the total samples. Reservoir temperature ranging from 87.12℃ to 277.64℃ and the temperature between 120℃, 200℃ and 277.64℃ made up 18.7%, 40.5% and 40.8%, respectively. It is shown that high temperature geothermal systems are widely distributed in the area. High temperature thermal storage areas are concentrated in southern Tibet, which are stronger in the south and weaker in the north and distribution in clusters along fault zones. Hot springs density and high temperature heat storage areas have good matching relationship with NS-trending fault zone and seismic activity in space, but they are not in accord with the volcanic rock distribution.

Abstract:Turpan basin is an important coal base in China, and studying the regional groundwater flow system is of great significance for regional water resources research. The well depths of the sampling points are mainly concentrated in more than 100 meters and less than 30 meters. All the samples can be divided into four groups based on the well depth,and in combination with the elevation effect of the isotope value and the locations of the sampling points, the nearby points are grouped into the same water system. An analysis shows that the north of the volcanic rocks belongs to the same type of groundwater flow system,while the water system in the south of the volcanic rock exhibits features of multistage flow system because of the reservoir building, the continuous improvement of the water conservancy facilities and the reformation of agricultural irrigation system; its forming condition is mainly influenced by natural and human activities. The isotope and TDS values of T1 point are higher, so it might have been the edge of the Aydingkol Lake, and the lake water level was shallow and isotope evaporation effect was obvious at that time. At the same time, loopholes were existent in the bedrock, the groundwater could flow from the north to the south of the basin.

Abstract:Cluster analysis and factor analysis were used to identify the chemical characteristics and influencing factors of karst groundwater samples collected from northern Bijie City in October, 2013. The results indicated that, due to the influence of geographical factors, water-rock interaction, soil and natural processes and human activity, the karst groundwater exhibited spatial variability, and there was significant variation in the chemical composition. Moreover, the essential hydrochemical characteristics(82%) and geochemical processes of groundwater can be explained by geographical factors, water-rock interaction, soil and natural processes and human activity. Among them, the water-rock interaction and human activity were the crucial influence factors. The HCO₃^-, SO₄^2-, Ca²⁺ and Mg²⁺ in groundwater mainly came from the dissolution of carbonate rocks, and the mining activity was another source. In addition, the factors of soil and water-rock interactions controlled the concentrations of Mg²⁺, HCO₃^- and CO₂. The concentrations of Cl^-, K⁺, Na⁺ and NO₃^- in groundwater were mainly influenced by human activities, including runoff of fertilizer and manure, pesticide application and discharge of sewage. The results are instructive for understanding the hydrochemical characteristics of karst groundwater in southwest China, and hence can improve local government's management and utilization of groundwater.

Abstract:Land subsidence induced by long-term excessive groundwater withdrawal has constituted a major geological disasters in Beijing plain. This paper is based on the deficiency of present leveling network, selected three kinds of influence factors, including the partition of hydrology geology unit, the groundwater level decreased rate of main exploitation layers and the total thickness of compressed layers. Based on GIS spatial analysis platform, the partition map of comprehensive affecting factors of Beijing plain is created, and divided into 448 partitions. On this basis, we optimized design the land subsidence leveling network, added 220 leveling points. Using geostatistical Kriging interpolation error variance as the accuracy evaluation index, we drew the standard deviation distribution contour map of land subsidence leveling network, found that the standard deviation of the optimized is lower than before. Proved that based on the background of geological environment, using the partition map of comprehensive affecting factors to optimize design the land subsidence leveling network is feasible. This method can be used as the basis of construction of leveling points.