Abstract:The rapid and scale development of source rock oil & gas is an important strategic option for the transformation of energy structure in China. Continental shale oil & gas is the most potential component type of source rock oil & gas in China, and the most important breakthrough target of “exploring petroleum into source kitchen” in the future. For the first time this paper puts forward the riewpoint that the development of Jurassic oil and gas in Sichuan Basin should be transformed from conventional structure- fractured oil and tight limestone and sandstone oil to porous shale oil & gas as soon as possible. Four new developments of shale oil & gas in Daanzhai Member are emphatically expounded. (1) The total oil production of four sets of organic- rich shale in Jurassic system is 245×108t, the total oil resources are 172×108t, and there are also considerable natural gas resources, and 67% of the oil and gas resources are concentrated in Daanzhai Member. (2) The second sub- member of Daanzhai Formation is the sweet section of Jurassic shale oil & gas. The thickness of black shale is generally 20~80 m, the average TOC value is more than 2%, the kerogen type is Ⅱ1~Ⅱ2, the Ro is mainly 1. 1%~1. 4%, is in the light oil- condensate oil window, the porosity of shale reservoir is generally 4%~6%, the shale fracture is developed, the brittle mineral content is generally more than 50%, the pressure coefficient is 1.2~1.8, and the residual hydrocarbon amount is more than 100~200 mg/g·TOC, with light oil and shallow burial depth, has geological engineering conditions comparable to North American shale oil and gas. (3) Three core parameters (Ro, organic- rich shale thickness and burial depth) for evaluation of shale oil & gas sweet area were optimized. The sweet area of shale oil in the second sub- member of Daanzhai Member was mainly distributed in the north- central part of the basin, with shale thickness of 20~50 m and area of about 2×104km2. (4) Three suggestions are put forward, including speeding up the implementation of risk target exploration and development testing by horizontal drilling and stimulated reservoir volumn fracking, strengthening the resource evaluation of the whole strata and speeding up the preparation of pilot test technical schemes, to promote the breakthrough discovery of oil and gas in Jurassic porous shale. The new understanding of Jurassic continental shale oil & gas in Sichuan Basin will provide an important theoretical basis for truly opening up the new journey of Jurassic source rock oil & gas “exploring petroleum into source kitchen ” and large- scale development.

Abstract:Living Chamaecyparis Spach only includes five species sporadically distributing in western and eastern North American, Japan and Taiwan. The reasons for the formation of modern regional distribution of Chamaecyparis have always attracted attention from botanists. Previous study analyzed the evolution of modern regional distribution of Chamaecyparis using modern molecular biology methods or fossil records, about which there is no consensus. In this paper, we revisited the origin and biogeographic history of Chamaecyparis based on detailed evaluation of the fossil evidence and the results of phylogenetic method. Fossil evidence indicates that Chamaecyparis had more species in the past geological period and was widely distributed in the mid to high latitudinal regions of the Northern Hemisphere since the early Cretaceous. We speculate from fossil records that the genus Chamaecyparis probably originated in Eastn Asia during the Early Cretaceous and spread to western North America via the Bering Land Bridge during the Late Cretaceous, and then to the high latitudinal region of North America. Absence of fossil record in eastern North America indicates that current Chamaecyparis in eastern North America might migrate from Europe or the high latitudinal region of North America. The European Chamaecyparis probably originated from the North America via North Atlantic Land Bridges or East Asia during the Oligocene. Local extinction of Chamaecyparis from Europe, western and central Asia and central North America might be a result of successive global climatic cooling in the Neogene and Quaternary glaciation. During the Neogene, Eastern Asia Chamaecyparis spread southwards to Japan and Taiwan and disappeared in the Asian continent. Finally, the genus Chamaecyparis limitedly occurred in western and eastern North American, Japan and Taiwan.

Abstract:The classification of uraniferous basin type is one of the most important foundation in uranium deposit prospecting, so far systematic comparative study of continental basins in northern China has not been carried out. Aided by prospecting practice of sandstone- type uranium deposits in northern China, unique sandsotone uranium metallogenic theory of fluctuating mineralization process, “Red & Black” syndepositional structures in ore- controlling, uplifts structures of basin margin in ore- controlling etc have been brought out, all the theories supervise prospecting and enriched through the practice, as a result prospecting breakthrough of sandstone- type uranium deposits was achived. Based on 30 million meters core information, on the basement of uraniferous formations time and uranium enrichment mechanisms, considering tectonic setting of basins and geotectonic evolution background, type classification of Mesozoic- Cenozoic uraniferous basins is proposed, including composite sedimentary basin, superimposed sedimentary basin and simple sedimentary basin. Composite sedimentary basin is a kind of uraniferous basin in which uraniferous formations are Mesozoic strata and sandstone- type uranium deposits lie in several formations, for example the uraniferous formations in Ordos Basin include Middle Jurassic uraniferous formation and Cretaceous formation. Superimposed sedimentary basin is a kind of uraniferous basin, uraniferous formations of which include Mesozoic structural layer and Cenozoic structural layer, for example, the Junggar Basin and Qaidam Basin. Simple sedimentary basin is a kind of uraniferous basin which only include Cenozoic uraniferous formations, for example, Longchuanjiang Basin. According to the space distribution between Tectonic magmatic belts and uraniferous basins, uraniferous basins are divided into the basin between magmatic belts and the basin in magmatic belts. Type classification of Mesozoic- Cenozoic uraniferous basins in northern China does not only have great significance in metallogenic environment of sandstone- type uranium deposits, metallogenic regularity and metallogenic model,but also in practical implications of prospecting.

Abstract:Reconstruction of shallow geomorphology and tectonics, based on the multiple closed system of low- temperature thermochronogical features, has received much attention and application in study of formation process of fold- thrust belt and foreland basin. The low- temperature thermochronogical age of the multiple closed system in the Longmenshan area, eastern margin of the Qinghai- Tibet plateau generally shows a decreasing trend from the foreland of the thrusting zone to interior of the plateau, and from NE to SW. The thermochronological ages of the Longmenshan fold- and- thrust belt varies greatly, distinctly larger than that inside the plateau, revealing a shallow erosion effect of enhanced fold- thrusting in the transition zone of basin and mountain during Cenozoic. Based on low- temperature thermochronological study and erosion thermal model of fold- thrust belt and foreland basin in the Longmenshan region, the study reveals that the Qinghai- Tibet plateau expands eastward at a rate of 5~10 mm/a, with an erosion rate of 0. 4~1. 0 mm/a, and a shortening rate of deformation with 0~15 mm/a. These data are consistent to features of geology and geodesy. Thermochronologic age characteristics of the W- E- trending multiple closed system in the eastern margin of the Qinghai- Tibet plateau reflect an eastward extension process of the steady plateau during the Cenozoic, i.e., the coupling process between the thrusting expansion of the Longmenshan fold- thrust belt and shallow erosion.

Abstract:Relay structures are common in active normal fault zones, and play an important role in fault interaction and linkage. In addition, relay structures also affects the evolution of drainage system and the transportation of sediments into basin, the process of fluids migration and trapping. The Langshan piedmont fault, which is located in the western margin of the Hetao Depression in Inner Mongolia, is a largescale normal fault system that has been continuously active since the late Cenozoic. There are different types of relay structures in the fault zone. Two types of relay zone have been identified: one is formed by two paralleled fault between which the rely ramp evolved from “soft link” to “hard link”; the other kind is wedgeshaped relay formed by a fault extending to another one. The preexisting structures in basement control and affect the distribution of the normal faults as well as the morphology of the relay zone. The NNE trending mylonitic foliation within the basement controls the strike of the linked normal faults zone, with the preexisting thrust fault plane partially utilized by normal faults. Newly formed faults migrate gradually to the basinward direction. The latest active faults are located at the margin of the basin and even within the basin. The Langshan piedmont normal fault extends southwestward gradually along the strike direction.

Abstract:The age and tectonic setting of the Al- rich metamorphic supracrustal rocks at the border of Shanxi, Hebei provinces and Inner Mongolia autonomous region has long been controversial. Based on the 1∶50000 regional geological survey in the Tianzhen area, two- stage Al- rich metamorphic supracrustal rocks have been identified in the Huai’an complex: Neoarchean garnet- biotite- plagiogneiss Formation- complex (GBPF) and Paleoproterozoic Huangtuyao Formation- complex (HTYF), respectively. These two Al- rich metamorphic supracrustal rocks are different in rock association, mineral assemblage, ore potentiality, isotopic age and geochemistry, indicating that they formed in the different depositional environments. The Neoarchean GBPF occurs in banded sheets, interlayers and lenticular in the field, and are mainly composed of garnet biotite plagiogneiss with a small amount of plagioclase leptynite，locally associated with banded iron formation (BIF). The mineral assemblage of GBPF is garnet+biotite+plagioclase+quartz±perthite±sillimanite. Geochemical analyses reveal that the garnet biotite plagiogneiss samples are peraluminous with the enrichment of Na2O, Al2O3 and CaO, low K2O, displaying weak Eu anomalies and relatively strong fractionation ((La/Yb)N=3. 69~27. 76). The Paleoproterozoic HTYF presents ribbon- like tectonic slices, which is a suite of khondalite series and occurs in graphite ore. The mineral assemblage of meta- pelite/sandstone in the HTYF is graphite+sillimanite+garnet+perthite+plagioclase+quartz. They are peraluminous with enrichment in Al2O3 and K2O, lower Na2O and CaO contents, and obvious negative Eu anomalies (δEu=0. 47~0. 80) and weak fractionation ((La/Yb)N=3. 37~10. 58). Two sets of Al- rich metamorphic supracrustal rocks have the similar characteristics of trace element in the spider diagrams, which show the enrichment of large ion lithophile elements such as Rb and Ba, low contents of high field strength elements such as Zr and Hf, and obvious depletion of Nb, Ta, P and Ti. The peak age of detrital zircons in the GBPF is at ~2. 45 Ga and the ages of detrital zircons in the HTYF are mainly around 1. 99~2. 3 Ga, suggesting that both sets of rocks have experienced granulite facies metamorphism- anatexis at late Paleoproterozoic (1. 81~1. 85 Ga). The protoliths of the Neoarchean GBPF were clay- bearing graywacke with low maturity, which probably derived from the weathered tonalite- granodiorite that formed in a continental island arc environment. The protoliths of HTYF were Al- rich claystone and graywacke with a small amount of carbonatite and quartz sandstone. The main sedimentary sources are mid- Paleoproterozoic (2. 3~2. 0 Ga) uppercrust felsic materials and the khondalite series may form in the relatively stable continental marginal environment. Two periods of Al- rich metamorphic supracrustal rocks in the Huai’an complex were involved in the Paleoproterozoic orogeny, and determination of the both is of important geological significance for studying the continental crustal evolution and tectonic framework reconstruction of the Neoarchean- Paleoproterozoic in the northern part of the North China Craton.

Abstract:Accurately determining the closure time of the Huoersen- Chaganchulu back- arc basin has important meaning for understanding the tectonic evolution history of the Alxa block and clarifying the spatial and temporal sequence of mineralizing events in the southern part of the Alxa continent. The back- arc basin disappeared in the Badanjilin fault zone. Although the eastern part of the Badanjilin fault zone was confirmed to close at about 275 Ma through the Chaganchulu Ophiolite Suite, the closure time of the western part of that fault zone is still unknown because of lack of ophiolite suite in the west. In this paper, the Tebai quartz diorite and the Guancaitaolugai granite porphyry in the western part of the Badanjilin fault zone were studied using petrology, geochemistry and zircon U- Pb dating. The results show that the Tebai quartz diorite belongs to the I- type granitoid, which is relatively enriched in LILE (like Rb, Th, U, K) and LREE, and relatively depleted in HFSE (like Ta, Nb, P, Zr, Hf, Ti) and HREEs, with weak Eu negative anomaly. Sr- Nd isotopic compositions of the Tebai quartz diorite, which are similar to that of OIB or EM I- type mantle source, suggest that the rock formed in the extrusion tectonic environment at 281. 7±1. 1 Ma when the Huoersen- Chaganchulu back arc basin was subducted to the Alxa continent. The Guancaitaolugai granite porphyry belongs to the A- type granitoid, which is relatively enriched in LILE (such as Rb, Th, U, K, Zr, Hf), LREEs, Zr and Hf, and relatively depleted in HFSE (such as Ta, Nb, P and Ti), Ba, Sr and Eu. Enrichment of LREE and depletion of HREE, distinct Eu anomaly, and Sr- Nd isotopic composition close to that of EM II- type enriched mantle source suggest that the Guancaitaolugai granite porphyry formed in the extensional tectonic environment at 272. 6±0. 8 Ma when the continent in the south of Huoersen- Chaganchulu back- arc basin collided with volcanic arc. The closure time of that basin in this paper should be no earlier than 272. 6±0. 8 Ma, but not later than 272. 6±0. 8 Ma. Combined with the understanding that the eastern part of Huoersen- Chaganchulu back- arc basin closed at ~275 Ma, this study argued that the Huoersen- Chaganchulu back arc basin closed at the time between 282 Ma and 272 Ma. Most of the mineralization events in the southern side of the Badanjilin fault zone are the response to the closure event of the Huoersen- Chaganchulu back- arc basin. Distributed along the Badanjilin fault zone, these deposits should be related to the Variscan magma activities, with the mineralization age close to 282~272 Ma.

Abstract:Yilashan ophiolite, located in the middle section of the Bangong lake- Nujiang suture zone, contains predominantly strongly- altered harzburgite and dunite, as well as podiform chromitite.The chromitite orebodies in the Yilashan area are mainly distributed in the northern part of the ophiolite, and consist mainly of dunite with minor amount of harzburgite. Electron microprobe analysis shows that the chromian spinel in the Yilashan chromite has Cr# values of 64. 2~73. 9, 46. 9~71. 6 of Mg#, TiO2 of 0. 03%~0. 31%, Al2O3 of 4. 5%~18. 7%, indicating that the Yilashan chromite should be high- Cr type chromite. The distribution patterns of REEs and trace elements of the Yilashan harzburgite are indicative of abyssal peridotite.The platinum group elements of chromite show enrichment of IPGE and depletion of PPGE, with right- dipping distribution patterns and no clear correlation between Pd/Ir and Pt/Pt*, reflecting that the Yilashan ophiolite had experienced the rock- melt reaction.Comparison study with other chromite ores suggests that the Yilashan chromite may be formed by the reaction of boninite melt with rocks in the subduction belt environment and undergo a multi- stage evolution process, i.e. the early MORB environment and the transformation of the late suprasubduction zone (SSZ).

Abstract:The Tanchong and Chenchong granitic stocks are situated in the northern margin of Xinxian batholith within the western Dabie orogen. They consist of monzogranite and granite porphyry, respectively. Elemental, whole- rock Sr- Nd and zircon U- Pb- Hf isotopic analyses have been carried out in this study, in order to understand their petrogenesis and tectonic significance. LA- ICP- MS zircon dating yields U- Pb ages of 133. 5±1. 1 Ma and 132. 9±1. 1 Ma for the Tanchong and Chenchong granites, respectively, indicating they formed in the early Cretaceous. These granites are characterized by high SiO2 of 69. 40% to 77. 82%, Al2O3 of 11. 72% to 15. 26%, a total alkali of Na2O+K2O=6. 40% to 8. 70% with K2O/Na2O>1 and A/CNK=1. 14 to 1. 66, and belong to the high- K calc- alkaline series. They are enriched in LREE with (La/Yb)N=22. 98 to 28. 64 and unapparent Eu anomaly, and depleted in Ba, Nb, Ta, P, Ti and Y. They have moderate ISr values (0. 707220 to 0. 707557) and negative εNd(t) values (-17. 7 to -18. 1), with two- stage Nd model ages of 2. 36 to 2. 40 Ga. Zircon εHf(t) values are negative (-21. 4 to -25. 8) with an calculated two- stage Hf model ages of 2. 24 to 2. 48 Ga. Their petrographic and geochemical data suggest that the Tanchong and Chenchong granites are fractionated I- type granites, which are derived from partial melting of ancient crust of the Yangtze Block. Their equilibrated residues are probably garnet- bearing. We infer that the magmas of Tanchong and Chenchong stocks were formed in a thickened continental setting. Combining regional synchronous magmatic rocks, we propose that tectonic collapse of the western Dabie orogen probably started at about 133 Ma, which is consistent with the eastern Dabie orogen.

Abstract:The Dahutang area in Jiangxi Province developed multiple- phased granitiods during the Late Mesozoic, which are closely associated with W- Cu- Mo mineralization. This paper performed the study of mineral chemistry, geochemistry, zircon U- Pb chronology and Lu- Hf isotope for porphyric- like biotite monzogranite and biotite granite porphyry from the study area. The results show that the porphyric- like biotite monzogranite formed at 145.6±1.4 Ma (Kunshan Pluton), 148.4±2.4 Ma (in the center of Yanziya Pluton) and 145.7±2.9 Ma (the edge of Yanziya Pluton), and the biotite granite porphyry formed at 143.7±2.4 Ma (Shiweidong Pluton). All the captured zircons in four samples were derived from the surrounding granitoids of Neoproterozoic. The geochemical characteristics show that the porphyric- like biotite monzogranite and biotite granite porphyry are similarly high in SiO2 (72.37%~73. 33% and 70. 16%~73. 8%, respectively), rich in Al with the aluminum saturation index A/CNK of 1. 23~1. 47 and 1. 30~3. 02, respectively; suggesting a high high- K calc- alkaline series. Rare earth and trace elements analyses show distinct differences between the porphyric- like biotite monzogranite and biotite granite porphyry. The porphyric- like biotite monzogranite is characterized by distinct HREE and LREE fractionation with an average (La/Yb)N of 26. 18 and obvious right leaning of REE distribution patterns, apparent negative Eu anomaly, enrichment in LILE (Cs, Rb, Th, U, K and Pb) and depletion in HFSE (Zr, Nb, Ti and Y), and low Ba and Sr. However, the biotite granite porphyry shows weak fractionation of LREE and HREE, with an average (La/Yb)N of 9.76, apparent Eu negative anomaly, “sea gull”- type REE patterns, and “M”- type four group effect, enrichment in LILE and depletion in HFSE. The εHf(t) of the porphyric- like biotite monzogranite has a range of -7.39~-5.19, with a two- stage model age (TDM2) of 1. 53~1. 67 Ga. Comprehensive analysis shows that the porphyric- like biotite monzogranite of Late Jurassic in the Dahutang area may be originated from partial melting of the Neoproterozoic biotite- granodiorite in middle- upper crust in the tectonic background of subduction of the Paleo- Pacific Plate into the South China Plate; while the biotite granite porphyry of Early Cretaceous originated from partial melting of the Neoproterozoic biotite- monzogranite in upper crust due to upwelling of the asthenosphere mantle in a tectonic transition background from subduction of the Paleo- Pacific Plate into the South China Plate to post- subduction extension. Besides, the biotite granite porphyry was replaced by Cl- rich fluids during the process of crystallization differentiation.

Abstract:The Larong W- Mo deposit, located in the southeastern part of the Leiwuqi- Zuogong metallogenic belt, is the first giant porphyry W- Mo deposit discovered in eastern Tibet. The metallogenic setting of this deposit is unclear due to lack of constraints on metallogenic chronology. Six samples of molybdenite from ore- bearing quartz veins were carried out for Re- Os isotopic dating, and the model ages obtained range from 91. 5±1.3 Ma to 92.3±1.3 Ma, with an isochron age of 90.6±2.1 Ma and a weighted mean age of 91. 8±0.5 Ma, indicating that the mineralization of the Larong deposit occurred at the Late Cretaceous. The Re content of molybdenite ranges from 53.0×10-6 to 86.1×10-6, suggesting that the metallogenic material originated from a crust- mantle mixed source. The metallogenic age of the Larong W- Mo deposit indicates that the Later Cretaceous tungsten polymetallic mineralization event occurred in the Leiwuqi- Zuogong metallogenic belt in the northeastern section of Bangonghu- Nujiang tectonic belt, with mineralization occurring in the Lhasa- Qiangtang collisional orogenic setting.

Abstract:The Zhutongjian uranium deposit, located in the northwestern part of the Xiazhuang ore field, is a breakthrough made during prospecting for uranium deposit in South China. Therefore, the discovery of uraninite- rich orebodies provides a new prospecting direction for uranium deposits in this area. The host rocks of the Zhutongjian uranium deposit are comprised of coarse- grained biotite granite and fine- grained biotite granite. In this paper, zircon LA- ICP- MS U- Pb dating, whole- rock geochemistry and Hf isotopes of the coarse- and fine- grained biotite granite were carried out to determine geochronology and petrogenesis of this deposit. Zircon LA- ICP- MS dating yields the diagenetic ages of 241.1±1.6 Ma and 233.6±1.4 Ma for coarse- and fine- grained biotite granite, respectively, indicating that the two plutons were formed in the Indasinian period. Two plutons are geochemically characterized by silica enrichment, K＞Na, strong aluminous, and low CaO/Na2O ratio. Trace elements analyses show that two plutons are enriched in LILEs (such as Rb) and HFSEs (such as Th, U, Ta, Hf), depletion in Ba, Nb, Sr, Ti, with slight positive Eu anomalies (δEu=0.212~0.269; δEu=0.155~0.258), revealing the S- type grantie. But the coarse- grained biotitic granite is of the disperser trace element patterns, indicating that it might have been affected by metasomatic alteration. In the primitive mantle normalized trace element pattern and chondrite- normalized REE diagrams, two plutons have high total REE content, distinct fractionation between LREE and HREE, right- dipping pattern, and distinct negative Eu anomalies. The Hf isotope compositions show the lower εHf(t) values of the coarse- grained biotite granite (from -10.9 to -9, with tDM2 age between 1951 Ma and 1834 Ma) and the fine- grained biotite granite (from -12.3 to -8.7, with tDM2 age between 2030 Ma and 1810 Ma), and the model ages of Paleoproterozic for the coarse- grained biotite granite (1951~1834Ma). Geochemistry and isotopic features indicate that the two plutons are strong aluminous S- type granite, and high Rb/Sr and low CaO/Na2O indicate that two plutons might be generated by partial melting of clay- rich argillaceous sedimentary rocks. Combined with the tectonic evolution of the South China, it can be concluded that the coarse- grained biotite granite formed in an extension setting during the main collision period of the Indosinian, while the fine- grained biotite granite probably formed in the transition stage of tectonic regimes from compression to extension.

Abstract:Several liquid oil seeps were discovered recently in the central Qiangtang block. Biomarker parameters indicate that crude oil of the seeps and the Beileico- Andarco Petroliferous Sequence (BAPS) are both derived from the Early Jurassic Toarcian oil shale. The Lower Jurassic oil shale characterized by high content of TOC, large potential of hydrocarbon generation and lower maturity of organic matter is the main source rock and major oil generating strata in the Qiangtang basin. Seismic reflection profile and drilling logs reveal that the Toarcian oil shale as thick as 110~150m covers all over the Northern Qiangtang Depression (NQD). Depth of the Toarcian oil shale ranges from 4500~3000m in most areas of the NQD to 3000~1000m in both wings of the Baodaohu anticline. Early Cenozoic thrust and deformation caused uplift of the Toarcian oil shale, which forms oil shale outcrops in the Bilog Co, Shenglihe, Changsheshan and Tuonamu Zangbu, and the Toarcian oil shale rise to as deep as 522~675m at core summit of the Bandaohu anticline. Methods of chloroform bitumen “A” and hydrocarbon generation rate of Toarcian oil shale sampled from different areas were taken for evaluation of oil resource in the focused region of NQD. It is estimated that the crude oil as much as 5000~10000 million tons occurs in the Bandaohu- Donghu area as large as 20000km2 after first time hydrocarbon generation of the Toarcian oil shale, and second time hydrocarbon generation of the oil shale forms 2440 million dons crude oil in the Cenozoic. The NQD contains mega volume of crude oil after two times hydrocarbon generation and is of prospective for oil exploration in the Qiangtang basin.

Abstract:Integrated analysis for natural gases, asphalt and gypsum deposits in the Gaoshiti- Moxi (Gao- Mo) area indicates that natural gases in the three reservoirs of the area underwent various degrees of Sulphate Reduction (TSR). The main evidence includes: 1) natural gases contain abundant H2S with a content of 0. 6%~3% at the Sinian Dengying Formation reservoir and 0. 2%~0. 8% at the Cambrian Longwangmiao Formation reservoir, and heavey δ34 S values of H2S (from 21‰ to 23‰), suggesting that S may source from inorganic gypsum through TSR reaction. 2) The S/C atomic ratios of the reservoir asphalt was about 0. 06~0. 4, much higher than the upper limit value (0. 034) of the asphalt formed through organic matter thermal cracking, and even a little higher than the S/C ratios (0. 06~0. 12) of the asphalt from the Puguang gas field where TSR had been proven strongly. 3) Gypsum deposited widely at the lower Cambrian in the Sichuan basin provided the materials as SO42- and Mg2+ for TSR. Formation waters in the Dengying Formation reservoirs contain high Ca2+/Mg2+ and low Na+/K+, indicating that dissolution of the salt and gypsum are quite common. Relative lack of SO4 2- in the formation water may result from the consumption by TSR reaction. Ethane should have been oxidized during TSR reaction, resulting in the increasing dry coefficient and much heavier δ13C2 values. Therefore, TSR reaction extents can result in differences of the natural gases in both Longwangmiao Formation and Dengying Formation. Relatively weak TSR reaction of the Longwangmiao Formation leads to reverse trend (δ13C1>δ13C2) of C isotopic composition in methane and ethane of natural gas, while relatively strong TSR reaction makes natural gases have normal distribution (δ13C1<δ13C2) of C isotopic composition in methane and ethane. If without oxidation of TSR, the reverse trend of C isotopic compositions in methane and ethane for Sinian and Cambrain natural gases in the Gao- Mo area should be commonly. The inverse trend (δ13C1<δ13C2) is consistent to that of highly mature shale gases in the basin and other areas in the world, indicating that primary origin of the natural gases in the Gao- Mo area should be correlated with the late- generated gases by shales. That can explain reasonably why the δ13C of methane is generally heavier than that of reservoir bitumen. This study is important to revisiting the accumulation mechanisms of the natural gases in this area.

Abstract:The eastern margin of the QinghaiTibet Plateau is the region with greatest topographic steepness, strongest internal and external dynamic forces, and extremely frequent climate change. The complex geological evolution process has made the region the most concentrated distribution and the most dangerous area of revival of the ancient landslides. Based on field investigation, drilling and geophysical exploration, InSAR monitoring, laboratory tests and numerical simulation analysis, this study analyzed the development characteristics, formation and evolution process and revival factors of the Garazong ancient landslide in Xianshuihe fault zone of western Sichuan. The results show that (1) The Garazong ancient landslide was formed in the late Late Pleistocene, about 42~30 ka years ago, with a volume of 3150×104 m 3, and belongs to a giant ancient landslide. (2) The Xianshuihe fault activity is the main controlling factor for the formation of Garazong ancient landslide. The cracking effect of previous strong earthquakes may result in the formation of ancient landslide and subsequent fault creeping further causes the cracking of the slopes, which increases the infiltration of atmospheric precipitation, and further expands the cracks. (3) SBAS- InSAR monitoring and numerical simulation results show that the overall stability of the landslide is good at present. But cracks, steep slopes and collapses in different degrees occur in many parts, with some suffering strong deformation, which can produce largescale revival slides due to strong earthquakes and extreme rainfall conditions. It is suggested that drainage and antiskid measures should be strengthened.

Abstract:By means of inorganic and organic chemical analysis, controlled source audio magnetotelluric sounding, high density resistivity and radon gas measurements, this study carried out detailed geological investigation for six ancient wellsin Jiuli village, DanyangCity, Jiangsu Province. The six well with interval spaces ranging from 30 to 200 cm have been boiling for more than 2000 years.The study found that (1) boiling gas in “boiling well” is mainly CO2, accompanied by a trace amount of radon gas and total volatile organic compounds (TVOC). All of the gas components in the “boiling well” have not been detected in nearby civil wells. (2) The contents of free carbon dioxide, calcium, iron, manganese, total dissolved solids, total hardness, bicarbonate, rare earth element etc. in “boiling well” water samples are significantly higher than that of other civil wells and lake water around the boiling wells. (3) The temperature of the well water in “boiling well” (about 19 degrees Celsius in summer) is basically the same as that of other civilian wells, with no anomaly observed. (4) The secondary faults of Maodong fault and basalt rock mass occur beneath the boiling well, and the concentrations of radon escaped to surface from the fault are significantly higher than that in other areas. (5) The existence of “boiling well” is closely related to the Maodong active fault. The boiling gas in “boiling well” comesmainly from deep crust or upper mantle, with the gas rising up along the fault zone to the earth surface. (6) The water in the six “boiling wells” tastes different because of the various contents of free carbon dioxide, calcium, iron, manganese and pHvalues. “Three clear three turbidity” features of the “boiling well” well water are closely related to ironcontent in wells. Three wells with high Fe contents are characteristic of turbid water and this may attribute to precipitation of ferric iron due to oxidation when water is exposed to air.