Abstract:Abstract：Analysis of geophysical data shows that there is no evidence for subduction of the Pacific plate beneath the continent of present eastern China except the Jilin-Liaoning (Jiliao) area, Northeast China. The tremendous change that has taken place in eastern China since the Mesozoic did not result from the subduction of the Pacific plate beneath continental China but is a major geological event caused by the reworking of the lithospheric mantle by mushroom structure formed by upwelling of asthenospheric materidals. The upwelling of asthenospheric materials resulted in the formation of a structure of coexistence of the new mantle and remnant mantle, reactivation of the lithosphere, folding of the crust of stable cratons, crustal thinning, repeated occurrence of earthquakes, active magmatism, ground subsidence and formation of vast marginal seas of the western Pacific. However, the thickness of the lithosphere did not decrease, and only the rate of lithospheric thinning decreased owing to the formation of the mushroom structure of the mantle. As a result, the lithospheric structure in the region is notably different from those in its surrounding regions. The region with the mushroom-shaped mantle covers the western Pacific region of the whole of Southeast Asia, including the east-central part of Northeast China, eastern North China, the southeastern margin of South China, Malaysia Peninsula, Indonesia, the Philippine, the Sea of Japan, Yellow Sea, East China Sea, South China Sea, the Caroline basin and the Philippine sea basin. There also exists a huge geodesic ellipsoidal positive anomaly corresponding to the low-velocity lithospheric mantle in the western Pacific region of Southeast Asia, which should be caused by mass surplus at the core-mantle boundary. It and its twin—the negative geodesic ellipsoidal anomaly caused by mass deficiency at the core-mantle boundary in the Indian Ocean-Tibet region—form a deep-level dynamic system controlling the structures of continental China. The age of this dynamic system might be Mesozoic or Late Paleozoic. The mantle circulation between brought about a tremendous change of the lithosphere below the western Pacific of Southeast Asia and drove the northward migration of the Indian plate and uplift of the Qinghai-Tibet Plateau.

Abstract:Abstract：Rayleigh surface waves propagating along 10,600 great-circle paths were selected using more than 20,000 long-period waveform records from 106 wide-band digital seismic stations distributed in Eurasia and the Western Pacific, and high-resolution 3D tomographic imaging of the crust and upper mantle in China and its adjacent regions was performed using the inversion of both dispersion analysis and waveform fitting. The high-resolution Rayleigh surface wave tomographic imaging indicates that: from the upper crust to 70 km depth, high velocities are displayed in the eastern part of East Asia and Western Pacific marginal seas, while very low velocities distributed in the western region centering around the Qinghai-Tibet Plateau; from the 100 to 250 km depth, a giant low-velocity anomaly belt ~250 to 400 km wide and ~8000 km long are shown in the eastern part of East Asia and Western Pacific marginal seas; from the 300 to 400 km depth, there is no appreciable velocity difference and high velocities are still displayed from the Tarim block to Yangtze block. There exist significant differences in lithospheric and asthenospheric structure between the eastern and western parts with longitude 110°E as the boundary. The western part is the lithospheric thickening convergent region formed by India-Eurasia collision, whereas the eastern part the lithospheric extension-thinning region arising from upwelling of asthenospheric material (rise of mantle thermal material). Due to the Paleocene India-Eurasia collision and convergence, the Indian lithospheric sheet was subducted beneath the Qinghai-Tibet Plateau at low angles, causing the plateau uplift and crustal thickening; thus the western part became a lithospheric region. In the Mid-Late Mesozoic, the lithosphere beneath the eastern margin of the East Asian continent was disassembled; as a result, the asthenospheric material upwelled and the lithosphere underwent extension and thinning, thus forming a giant low-velocity zone, which later evolved into the East Asian rift system. The present marginal seas and trench-arc-basin system of the Western Pacific was formed by interaction of the Pacific plate, Australian plate and Eurasia plate in the Mid-Late Cenozoic.

Abstract:Abstract：Many researchers have confirmed that there occurred southward subduction of the small Bangong Co-Nujiang ocean basin in the Late Jurassic. Recently a sequence of Late Jurassic island-arc volcanic rocks has been found at the northern side of the Dongqiao ophiolite zone in the central part of the Bangong Co-Nujiang belt. This sequence of volcanic rocks, named the Gacangjian volcanic rocks, is distinguished from the Dongqiao ophiolite zone by its weak deformation in its inner part and its geochemical characteristics indicates that it formed in an island arc environment. The evolution of the volcanic rocks was characterized by eruption of tholeiitic-calc-alkaline magma through predominance of calc-alkaline volcanism to eruption of arc shoshonitic magma accompanied by Nb-rich arc basalt at the late stage, suggesting a mature arc. All of these demonstrate that northward subduction had taken place within the Bangong Co-Nujiang ocean basin by the Late Jurassic. This discovery has great significance for the reconstruction of the complete tectonic evolution of the Bangong Co-Nujiang belt and establishment of the tectonic framework of the Qinghai-Tibet Plateau.

Abstract:Abstract：Research into detrital zircons is an effective approach to the sources and provenance features of detrital materials and depositional ages and environment. The authors performed SHRIMP U-Pb dating of 47 detrital zircon grains from Carboniferous sandstone at the southern piedmont of the Harlik Mountains, eastern Xinjiang, and obtained ages of 388 to 949 Ma, clustering at 418 to 482 Ma. Based on these dating data, combined with the mineralogical characteristics and CL images of zircons as well as the regional geological data of the Harlik Mountains, we may draw the following conclusions: (1) the youngest detrital zircon age of the studied sandstone is 388±9 Ma, implying that this sequence of the strata is not older than Middle Devonian in age and possibly was deposited in the Late Carboniferous according to the regional geological correlation; (2) the detrital materials of the studied sandstone were mainly derived from magmatic rocks related to the Early Paleozoic arc of the Harlik Mountains; and (3)the tectonic evolution of the Harlik Mountains progressed through the Middle Ordovician to Early Silurian magmatic arc related to northward subduction of the oceanic lithospheric plate represented by the Kanggurtag oceanic crustal fragment, Carboniferous back-arc basin and terminal Late Carboniferous back-arc uplift. The last event was probably the main cause for the present difference in geological outcrops between the Harlik and Bogda mountains.

Abstract:Abstract：The major granitoid rocks in a Late Paleozoic rift area, southeastern Inner Mongolia, are quartz diorite, tonalite, granodiorite, monzogranite and syenogranite. SHRIMP zircon U-Pb dating of the quartz diorite yielded ages of 313±5-323±4 Ma, indicating a Late Carboniferous age. Both the Qianjinchang and Daqên monzogranite plutons are intruded into paralic clastic rocks of the Permian Shoushangou Formation (P1ss) with a clear intrusive contact relationship. The SHRIMP U-Pb zircon ages for the two plutons are 280.8±3.6 Ma and 281.5±0.5 Ma respectively, indicating a late Early Permian age. The Ulan Tolgoi syenogranite has an age of 259 Ma and the Yangjiaolin Gol monzogranite has U-Pb ages of 246-216 Ma, suggesting that another intrusion peak occurred during the Late Permian-Triassic. There were three intrusion peaks in the Carboniferous-Permian (partly Triassic) rifting period, i.e. the Late Carboniferous quartz diorite intrusion peak, Early Permian tonalite-monzogranite intrusion peak and Late Permian monzogranite-syenogranite intrusion peak.

Abstract:Abstract：There outcrop many fresh greenschist tectonic blocks in the western segment of the southern Altyn Tagh marginal tectonic belt. Intensive petrological and geochemical studies show that: the protoliths of the greenschist are basic volcanic rocks (tholeiites), and in addition three types of basalt are also recognized, namely, oceanic island (within plate) basalt (OIB), mid-oceanic ridge basalt (E-MORB) and island arc basalt (IAT). The E-MORB have similar geochemical characteristics, with low Ti (TiO2=0.93%-1.75%, average 1.34%) and P (P2O5=0.09%-0.15%, average 0.13%) and the high field strength elements Zr=(79-146)×10-6, Hf=(2.6-3.5)×10-6 and Nb=(6.6-15.3)×10-6, being LREE-depleted or slightly enriched. IAT have lower Ti (TiO2=0.4%) and P (P2O5=0.08%) than those of MORB and the high field strength elements Zr=56×10-6, Hf=1.6×10-6 and Nb=5.9×10-6, being LREE-slightly enriched. OIB have high Ti (TiO2 = 1.96%-3.08%, average 2.49%) and P (P2O5=0.23%-0.34%, average 0.26%), with the high field strength elements Zr=(204-237)×10-6, Hf=(4.2-7.2)×10-6 and Nb=(14.6-22.1)×10-6, being LREE-enriched. The presence of the OIB, E-MORB and IAT assemblage suggests the existence of an ocean basin in the southern Altyn Tagh marginal tectonic belt during the Early Paleozoic.

Abstract:Abstract：The contents of platinum group elements (PGE; Ir, Ru, Rh, Pt, Pd) in orthopyroxenite and garnet websterite in Maowu have been determined using the nickel sulfide fire assay, combined with ICP-MS. Analysis indicates that： the PGE abundances are not related to rock types, and the primitive mantle-normalized PGE patterns have negative slopes, showing the fractionation of Pd and Ir. The formation of these PGE characters was constrained by the presence of PGE in rocks. Analysis of the PGE-carrier phases shows that PPGE are concentrated in Cu-rich sulfides, while IPGE occur as quasi-residual, insoluble monosulfide solid solution. Crustal contamination also contributed to the fractionation of platinum-group elements. In addition, the presence of fluids during rock formation resulted in selective mobilization of Pt and Pd. Therefore the combined action of monosulfide solid solutions and fluids produced the characteristics of PGE distribution in quasi-residual pyrolite of the Maowu ultramafic rocks.

Abstract:Abstract：Evaporation and leaching experiments were performed on two specimens of similar sulfide ores by using meteoric water in the same physico-chemical (normal temperature and pressure and oxidizing) environment to simulate weathering of rocks and ores in arid areas and humid areas. It took 603 days for the experiments. The experimental results show the following： appreciable changes took place in hardness, color and mineral composition of the specimen for the evaporation experiment, while the specimen for the leaching experiment in the main kept the features before the experiments in respect to the hardness, color and mineral composition. The pH values of the soaking liquid for the evaporation experiment first decreased, then increased and finally remained constant at 6.5-7; whereas the pH values of the leaching liquid for the leaching experiment first decreased and then was constant at ~5. However, cation concentrations in the soaking liquid were higher than those in the leaching liquid. The experimental results indicate that evaporation causes rock and ore weathering more easily than leaching. Evaporation is mainly a chemical reaction. So the experimental results are a stern challenge to the traditional idea that physical weathering predominates in arid areas.

Abstract:Abstract：The oolitic shoal reservoir in the Feixianguan Formation in the northeastern Sichuan basin, which has undergone strong diagenesis, is an important exploration target in the Sichuan basin. On the basis of an integrated analysis of all kinds of data, such as the core, common thin sections, mold thin sections, cathodoluminescence images, carbon and oxygen isotopes, trace elements and fluid inclusions, the paper deals with the main type, mechanism and product of diagenesis and analyzes the effects of diagenesis on the reservoir. Cementation and compaction were the leading destroyers of primary pores and part of secondary pores. Mixed-water dolomitization, corrosion (karstification) and rupturing were the leading builders of secondary pores and the solution pores, solution cavities and fractures produced by them are the dominant accumulation spaces and migration passageways for gas. The physical properties of the reservoir are mainly controlled by diagenesis, which controlled the evolution of pores.

Abstract:Abstract：The Guang'an gasfield is a large one newly discovered in the Sichuan basin in 2006 and has identified reserves of more than 500×108 m3. It is also the largest gasfield ever discovered in the Upper Triassic strata in the Sichuan basin up to now. Because the gas generation intensity of Upper Triassic hydrocarbon source rocks in the study area is less than 20×108 m3/km2, theoretically, no ideal conditions for the formation of a large or medium-sized gasfield are available in the area, and consequently the genetic type and source of natural gas in the gasfield are a problem that needs urgent solution. An intensive analysis of the components and carbon isotope data of the gas shows that the gas is coal gas. According to a correlation of gas sources, the possibility that the overlying and underlying source rocks provide gas is ruled out. In other words, the formation of the Guang'an gasfield is due to self-generation and self-accumulation of gas in the coal measures of the Upper Triassic Xujiahe Formation. Finally, an analysis of the gas migration pathway reveals that the proximal lateral migration is the main cause for the formation of the large Guang'an gasfield.

Abstract:Abstract：The main lithologies in the Cretaceous-Paleogene in the northern Tarim basin are litharenite and feldspathic litharenite, which are in the middle diagenetic stage. The main pore spaces are relict primary intergranular pores, intergranular solution pores, intragranular solution pores, pores in grain films and matrix micropores. However, there are certain differences in rock composition, diagenetic evolution and pore association types in different areas and intervals of strata, thus resulting in appreciable difference in hydrocarbon storage capacity, which is mainly controlled by the primary sedimentary environment and diagenesis. According to the lithologies and physical parameters of Paleogene and Cretaceous reservoirs in different areas and tectonic belts, the reservoirs in the region mainly fall into four classes. Classes I and II are main targets for oil and gas exploration and reservoirs of class III belong to low-permeability ones and may serve as targets for gas exploration, while the class IV reservoirs are very low-porosity, very low-permeability and very compact type reservoirs and even non-reservoirs.

Abstract:Abstract：More than 20 orogenic gold mineral occurrences have been discovered and explored in the northern Qaidam margin-East Kunlun region. They are the product of the late Caledonian and late Variscan-Indosinian multiple collisional orogeny. Based on a study of fluid inclusions in 12 gold deposits in the region, two kinds of ore-forming fluids are recognized in these orogenic gold deposits: low-salinity H2O-CO2-NaCl-CH4 fluids and low-salinity H2O-CO2-NaCl±CH4 fluids. The former, whose XCH4, XCO2 and XH2O values are 0.14-0.34 (mean 0.24), 0.11-0.59 (mean 0.34) and 0.64-0.31 (mean 0.42) respectively, temperatures range from180 to 270℃ and pressures range from 180 to 560 MPa, are the product of late Caledonian collisional orogeny and mainly flowed along the ductile deformation zone between the base of the upper crust and the upper part of the middle crust below the boundary of the Caledonian collisional orogenic belt and formed extensive gold mineralizations in the region. For the latter, the values of XCH4, XCO2 and XH2O are 0-0.12 (mean 0.06), 0.18-0.25 (mean 0.21) and 0.79-0.69 (mean 0.73), the temperatures range from 280 to 449℃ (mostly 280-360℃) and the pressures range from 80 to 230 MPa. They were mainly related to late Variscan-Indosinian collisional orogeny and influenced by magmatic intrusion in some deposits. The fluids flowed extensively along the upper crust below the boundary of the late Variscan-Indosinian collisional orogenic belt, thus resulting in the final location of orogenic gold deposits in the region. The salinities of the two kinds of fluids are approximately consistent, generally varying from 1.4 to 11.4 wt% NaCl equiv and clustering at 2.7-9.1 wt% NaClequiv. The results of pressure-depth conversion of the ore-forming fluids indicate a process of strong crustal uplift during the late Variscan-Indosinian collisional orogeny in the region, with the maximum uplift magnitude up to 12 km. This shows that the orogenic gold mineralizations in the region took place in a background of crustal uplift.

Abstract:Abstract：The paper discusses the methods and theories of mineral search at depth on the basis of the experience obtained by the authors in exploration of succession mineral resources in crisis-facing mines of important mineral resources in China and the practice of mineral search at depth in recent years. The authors think that geological research, applications of geophysical and geochemical exploration techniques and drilling and tunneling are three basic factors of mineral search at depth. Geological research is the basic condition, geophysical and chemical prospecting is the technical support condition and drilling and tunneling is the condition for realization. They constitute the basic technical line. The paper discusses in an all-round way the studies of the characteristics of geological processes, ore field structure and indications for ore-forming processes. The study of the characteristics of geological processes related to ore-forming processes is basic work for determining the idea of mineral search. These geological processes include deposition, magmatism, volcanism, metamorphism and integrated ore-forming geological processes. The study of ore field structure puts forward the sedimentary structure system, volcanic structure system, intrusive structure system, fault structure system, fold structure system, compound structure system and post-ore structure system, as well as their applications in mineral search at depth. The study of indications of ore-formation processes includes studies of the indications of ore-forming characteristics and indications of physical-chemical conditions of ore fluids. The authors also put forward the theoretical basis of geochemical barriers to ore hydrothermal fluids and their research methods and application in search of mineral resources at depth.

Abstract:Abstract：Knowledge of the porphyry Cu (Mo) ore belts in the Central Asian metallogenic domain originates from the division of the peri-Balkhash-Ili volcanic-intrusive belt in Kazakhstan and confirmation by the geophysical field. Through the definition of the Kazakhstan-Junggar ring-shaped magnetic anomaly zone, the authors lay a geophysical foundation of the porphyry Cu (Mo) ore belts of the Central Asian metallogenic domain and recognize their coupling relation to the volcanic-intrusive belts at peripheries of the Kazakhstan-Junggar block. On that basis, an embryo of the porphyry Cu (Mo) ore belts in the Kazakhstan-China-Mongolia Central Asian metallogenic domain is established.

Abstract:Abstract：The Ganheba gold deposit is the first gold deposit found in the Mianxian-Lueyang tectonic mélange belt of the Qinling orogenic belt. The formation of the gold deposit went through the phase of deposition of sedimentary rocks and formation of the basement in the pre-Mianxian-Lueyang restricted ocean, the phase of gold preconcentration in the sediments of the Mianxian-Lueyang restricted ocean and the phase of continental collision and amalgamation between the Yangtze plate and Qinling plate and structural stacking and reworking and gold concentration derived after orogeny. Favorable host rocks (containing 3.66×10-9 Au) is the material basis for gold mineralization and ductile-brittle progressive structural deformation is the key ore-controlling factor. The Ganheba gold deposit is the product of the combined action of the rocks and the structure. Fluid inclusion study shows that the homogenization temperatures of the ore fluids ranged from 137 to 280℃ in the main mineralization stage of the deposit, which shows the features of mesothermal-epithermal mineralization. The salinities ranged from 4.5 to 23.1wt% NaClequiv. at the early to middle stages of mineralization．The δ34S values of pyrite ranged from +9.91 to +15.45‰, showing the feature of enrichment in heavy sulfur. The sulfur of volcanic origin shows strong fractionation, and in addition, crustal sulfur from sedimentary rocks was also introduced, showing the feature of the mineralization that underwent strong geological reworking in the late phase. Gold occurs mainly as independent microgranular minerals and the paragenesis of ore elements are Au-Ag-As-Sb-Cu-Pb-Zn, showing the geological features of a Carlin-like gold deposit.

Abstract:Abstract：Crust-derived inorganic CO2 in the Yinggehai basin, northern South China Sea, has unique migration and accumulation characteristics, complex occurrence features and huge resource potential. Based on the present exploration and research extent, more than 1000 billion m3 of CO2 resources and 200 billion m3 of CO2 geological reserves are obtained in this basin. The latter rank first among China's CO2 geological reserves, which is also infrequent in the world. So the basin has quite large resource potential and comprehensive exploitation and utilization perspective. Because of the multiplicity, CO2 not only can be used in national economy and industrial and agricultural production but also is the main greenhouse gas that may cause the El Ni?觡o and seriously affect the global eco-environment and natural ecologic equilibrium. Therefore, how to exploit and utilize such a huge amount of CO2 resources comprehensively, bring its market potential into full play and accelerate economic development is now a crucial scientific and technological subject facing natural gas exploration and exploitation in this area.

Abstract:Abstract：Kunming, Chongqing and Chengdu in southwest China are a lakeside city in the Yunnan-Guizhou Plateau, a mountain city beside a river and a plain city respectively and have different geological environments. Many environmental geological issues closely related to the sustainable development of cities have occurred to different extent in these cities with their fast development from the 1980s. Kunming is confronted with land subsidence and soft ground. Frequent landslide and rockfall events have obstructed Chongqing's development and expansion. The integrity and runoff ability of the groundwater system in the giant diluvial-alluvial fan of the Minjiang River have been seriously destructed by the rapid development of Chengdu located above a ground reservoir of the western Sichuan plain. Environmental geological issues should be the most important factors considered in city planning and drafting a rational city-planning scheme is the effective approach to inhibiting the deterioration of the geological environment.

Abstract:Abstract：Establishing a rational model of groundwater exploitation and utilization is very important for the construction of an energy base and mitigating its urgent shortage of water resources. Based on an analysis of the conditions of groundwater in the Nanliang-Baibao area, a 3D groundwater flow conceptual model and a numerical model are constructed in a selected typical area. By modeling the shape of the drawdown cone using different exploitation scenarios with different single well yields and different well spacings, the manner of rational groundwater exploitation and utilization is studied. The analytical results indicate that the groundwater pumping wells should be laid out in the main river valley and that the linear well array should be used to intercept the river discharge as the yield. It is advisable that the linear pumping rate should not exeed (0.02-0.03)×104 m3/(d·km).

Abstract:Abstract：Previous studies paid little attention to the influences of the factors in the soil environment on karst processes. Using the State Jinfo Mountain Nature Reserve in Chongqing as an example, field experiments were conducted and data collected for field standard limestone tablets and the CO2 concentration, moisture, porosity, pH, and organic matter content of soils. The influences of the soil environmental factors in different land-use patterns and their coupling on the dissolution rates of carbonate are studied. The results indicate the following: There is appreciable difference in average dissolution rates of limestone tablets. They are from the highest to lowest are as follows: bamboo land, woodland, grassland, shrub land and herbal shrub land. The dissolution rates of limestone tablets and pH show a good negative correlation, while the dissolution rate of limestone tablets shows a good positive correlation with soil moisture and porosity. The karst processes at top of Jinfo Mountain are stronger than those at the foot, which is related to the severest drought in a hundred years in Chongqing. The CO2 concentration, moisture, porosity, pH and organic matter content affect the dissolution rate of the limestone tablets, and in addition, the multi-variable coupling of the factors in the soil environment also affects the dissolution rate of karst.

Abstract:Abstract：Marine carbonate rocks of the Bi Qu Formation are one of the most important hydrocarbon source rocks in the North Qiangtang basin. This paper reveals the geochemical characteristics of the source rocks on the basis of the abundance， types and maturity of organic matter， and especially biomarker analysis. The results show the following: hydrocarbon source rocks occurred in the reducing environment， the organic source material is mainly lower aquatic plants mixed with some higher plants， and the organic matter of the hydrocarbon source rocks has a high degree of thermal evolution and is at a high maturity stage.

Abstract:Abstract：The paper discusses the influence of soil parent rocks on the output and quality of Chinese date in the agrogeological context. Investigation shows that Chinese dates with a good quality and a high output in the Xingtang mountainous area, Hebei, are mostly distributed in the biotite-plagioclase gneiss area. It is mainly because, in comparison with other types of mantle rock, biotite-plagioclase gneiss is thick with well-developed cracks and contains higher P, Sr and ∑REE and its contained K is higher and occurs in the slow-effect state in biotite and thus is easily absorbed by plants. Analysis of the soil geochemical background, the area of good-quality Chinese date best coincides with the area rich in P, Sr, Na and ∑REE, while Ni and Cr are lower. It also validates the consistency of the areas of Chinese date with the areas of its soil parent rock—biotite-plagioclase gneiss.

Abstract:Abstract：The stratigraphic division in the Kumtag sand-ridge, East Tianshan, has long been in dispute. During 1∶50,000 regional geological and mineral survey, the conodonts Streptognathodus suberectus and Idiognathoides sinuate and the corals Pelalaxis intermedia, Lithostrotionella rarivesicula and Fomichevella kiaeri were found in two sequences of carbonate rocks in the Kumtag sand-rigde area north of the Kanggurtag deep fault, East Tianshan. The two sequences of strata are Late Carboniferous Luosuan-Dalaanian and Dalaanian-Xiaodushanian in age respectively, assigned to the Dikan'er Formation and Qishan Formation in the Karlik stratigraphic area respectively. Two suites of volcanic rocks are separated by the two sequences of sedimentary rocks. They are very easy to recognize and distinguish in the field and correlate at a regional scale because their spatial distributions are relatively fixed and the features of rock associations are distinct. Their ages are Early Carboniferous and Late Carboniferous respectively. The Qi'eshan Group can be further divided in ascending order into the Xiaorequanzi, Dikan'er, Qi'eshan and Qishan formations.

Abstract: