Abstract:Abstract:The Dur’ngoi ophiolite in the north Qinghai-Tibetan Plateau consists of meta-peridotite, mafic-ultramafic cumulate, sheeted dikes and basaltic lavas. The meta-peridotite consists of dunite, harzburgite, lherzolite, feldspar-bearing lherzolite and garnet-bearing lherzolite and contains residual spinel with Cr#s [100*Cr/(Cr+Al)] of 30-57 and Mg#s [100*Mg/(Mg+Fe2+)] of 50-75, indicating an Al- and Mg-rich series. The meta-peridotites have a relatively narrow range of composition with Mg#s of 89.2-92.6, Al2O3 contents of 1%-4 % and slightly depleted REE patterns, indicating that they represent relict mantle material that has undergone intermediate to low degrees of partial melting. Garnets in the lherzolite are andradite enriched in Ca and Fe and depleted in Mg and Al (And 95-97, Pyr 0.27-5.06,Gro 0-2.62), indicating that they formed by metamorphism. Cumulates consist mainly of dunite, wehrlite, pyroxenite and gabbro. The dunite contains minor feldspar, mostly replaced by chlorite and clay minerals. The wehrlite consists of olivine, diopside and minor plagioclase. A well-layered gabbro-pyroxenite complex is defined by variations in modal plagioclase and pyroxene. Blocks of garnet-pyroxenite or rodingite are locally present in the meta-peridotite. Garnets in the cumulates are grossular (Gro 69.19-89.93；And 9.12-18.84；Br 0.73-11.63), formed by metamorphism. Diabase dikes are depleted in LREE with (La/Sm)N ratios of 0.49-0.75 and have flat HREE patterns with positive Eu anomalies (δEu =1.14-1.27). Basalts have REE patterns similar to those of MORB with (La/Sm)N ratios of 0.46-0.95 and small negative Eu anomalies. The basalt compositions, particularly their consistent REE patterns, suggest no contamination in their magma source and little differentiation during crystallization. SHRIMP U-Pb dating of zircons from the basalts yielded 206Pb/238U ages of 276-319 Ma (average 308.2±4.9 Ma). The Dur’ngoi ophiolite is interpreted as a dismembered fragment of paleo-oceanic crust formed at a fast-spreading mid-ocean ridge. Intense serpentinization and carbonization reflect hydrothermal alteration on the seafloor associated with formation of the Dur’ngoi Cu-Co-Zn massive sulfide deposit. The ophiolite was probably emplaced during closure of the paleo-Tethyan ocean basin and is believed to mark the suture between Gondwana and Eurasia.

Abstract:Abstract: We have analysed the major element, trace element and boron isotope composition of borates, tourmaline-rich rocks and their non-tourmalinised equivalents from the lower portion of the Paleoproterozoic South Liaohe Group (N.E. China). These rocks host economically important borate deposits that formed in an evaporitic environment. The sequence contains abundant tourmaline in leptynites, stratiform tourmalinites, quartz-tourmaline veins and pegmatites that have spatial and temporal relationships to the borates.Tourmalines distal to the borates have lower δ1 lB values (-5.2 ‰ to +3.6 ‰) than those proximal to the borates (+1.8 ‰ to +9.4 ‰)that are slightly lower than those of the borates (av. +10.5 ‰). Mg/Fe ratios of the distal tourmalines are low (<1.0) relative to proximal tourmaline-rich rocks (>1 to 2.6). These differences reflect the fact that the evaporites are a major source of B and Mg. The geochemistry of immobile elements in the stratiform tourmalinites is similar to that of their unmineralised equivalents (interpreted as meta-tuffites), suggesting that the tourmalinites formed via alteration of Al-rich tuff layers by boron-rich fluids derived from leaching of the underlying borates. Field evidence and geochemical data support a three-stage model of tourmaline formation. The first stage was coeval with deposition of the borates, during which boron from hot springs was adsorbed by clay minerals in the tuffs that were later metamorphosed to tourmaline-bearing leptynites. In the second stage, hot fluids leached boron from the evaporites and passed through overlying tuffs to form the stratiform tourmalinites. During later emplacement of granites at the base of the sequence, felsic veins and pegmatites intruded the borates and tourmalinites. Boron from the borates diffused into the felsic veins, forming coarse-grained tourmaline at their margins. This association of tourmaline with the borate deposits emphasizes the significance of tourmaline-rich rocks as a prospecting guide for borates in this area and has implications for the origin of tourmalinites in other metamorphic terrenes.

Abstract:Abstract：Basic-ultrabasic rocks in an extensional regime are closely related to copper-nickel deposits. The geochemistry and petrology of basic and ultrabasic rocks on the northeastern margin of the Tarim plate (whose age may be traced back to Mesoproterozoic) and their tectonic setting are studied in this paper. The authors consider that the basic-ultrabasic complex in this area may be classified into two types. One type formed in the early stage of rifting (Mesoproterozoic) and the other type formed in the culmination of rifting or back-arc basin stage (Paleoproterozoic). The latter may be assigned to the ophiolitic complex category, while the former is closely related to the nickel-copper metallogenic system, but difficult to assign to any of the available basic-ultrabasic categories, which is a new type. The authors suggest that the former type be named continental-margin rift type basic-ultrabasic rocks. The Sm-Nd model age of this type of rock in this area is TDM=1 026－1 749 Ma. The association of its plutonic rocks (Heishan complex) is quartz syenite-gabbro-hornblende gabbro-mica-bearing plagioclase-hornblende harzburgite-mica-bearing hornblende harzburgite-mica-bearing plagioclase-hornblende peridotite–pyroxenite. The average m/f ratio of the ultrabasic rocks is 5.5 and ∑REE is 20.9×10-6 to 64.71×10-6, with an average of 29.91×10-6, and the LREE is slightly enriched. The TiO2 content of the gabbros is 0.92%. The association of their hypabyssal rocks (North Heishan complex) is grayish black, fine granular hornblende gabbro (gabbro porphyrite)-dark greenish black, finely granular chloritized gabbro norite-deep black medium-grained olivine websterite. Their TiO2 content is strongly enriched . In hornblende gabbro (gabbro porphyrite),TiO2 is 1.32%-3.32%; MgO and CaO are depleted; Rb, Sr, Y, Zr, Nb, Ba, Cs, Hf, Ta, Th and U are strongly enriched; Sc, V and Cu are slightly enriched; Cr, Co and Zn are depleted; and LREE is slightly enriched. All these indicate that a back-arc extensional regime had already appeared on the northeast margin of the Tarim plate in the Mesoproterozoic, and that magmas were separated from the mantle multiple times under this regime.

Abstract:Abstract: Sm-Nd and K-Ar dating of layered gabbro in the Shemalagou ophiolite in the western segment of the Bangong Co-Nujiang ophiolite belt indicates a combined internal and whole-rock Sm-Nd isochron age of 191±22 Ma and K-Ar ages of 140±4.07 Ma and 152.30±3.60 Ma. According to the dating results, combined with geological data, it is suggested that the Sm-Nd age represents the age of ocean basin opening, i.e. Early Jurassic, while the latter is the time of alteration influenced by the subduction of oceanic crust. Based on the available data in the central and eastern segments of the Bangong Co-Nujiang ophiolite belt, the ages of opening, subduction and closing of the ocean basin are discussed. The authors think that the Bangong Co-Nujiang ocean basin probably opened from east to west simultaneously in the Early Jurassic, began to be subducted southward in the Middle Jurassic and finally closed at the end of the Early Cretaceous.

Abstract:Abstract：The paper discusses the Evolution and climatic change of Nam Co of Tibet and an ancient large lake in the northern Tibetan Plateau since the late Pleistocene based on the field leveling survey and laboratory analysis. There are 6 lake terraces along the lake shore of Nam Co less than 48 m above the lake level and highstand lacustrine sediments 48 m to 139.2 m above the lake level. Research shows that the development of Nam Co and evolution of the ancient large lake in the southeast of the northern Tibetan Plateau underwent three stages: ① The ancient large lake stage at 116—37 ka BP, ② the outflow lake stage at 37—30 ka BP, and ③ the Nam Co stage since 30 ka BP. In the ancient large lake stage, a large number of large, medium-sized and small, modern lakes in the southeast of the northern Tibetan Plateau such as Nam Co, Siling Co, Zhari Namco Co and Tangra Yumco were joined together to form a single great lake, whose areal extent might overstep the watershed between the northern Tibet endorheic drainage system and exorheic drainage (Nujiang River) system. It might also be joined with other ancient lakes in the south and west of the north Tibetan Plateau, forming a unifying “ancient large lake”in the northern Tibetan Plateau. Through the comparison between the ages of the lacustrine sediments of Nam Co and the deep-sea oxygen isotope records and an integrated study of more soluble salts, pH values, geochemistry and ostracods and sporopollen, the authors have found that the lacustrine sediments record the information of lake evolution and climatic change since the late Pleistocene. Data show that: during the ancient large lake stage the lake level was the highest and the climate was mild and slightly dry; during the outflow lake stage the lake level lowered sharply and the air temperature and humidity were slightly higher than the present; and the climate got arid increasingly, temperatures fluctuated and the lake level dropped continuously after the warm and humid climate in the Holocene Climatic Optimum since the Nam Co stage. Based on the general trend of getting arid gradually, the climate in the region experienced several marked cold-warm and dry-humid fluctuations since Late Pleistocene.

Abstract:Abstract:The biostratigraphy of the Huanglong and Laohudong formations in Zhejiang is less studied, and especially the fusulinid zone is not systematic. So there are some problems about the correct stratigraphic division and correlation. The authors intensively measured the stratigraphic section of the Laohudong Formation and Huanglong Formation in Tonglu, Zhejiang Province, and gathered samples of fusulinids from the section, and by thin section study the authors established two fusulinid zones; they are in ascending order: the Profusulinella simplex zone and Fusulinella bocki-Fusulina mayiensis zone (both belong to the Dalaan Stage). Moreover, the biostratigraphic and lithostratigraphic correlation has been made between this section and the section of the two formations in Changxing, Hangzhou and Changshan in Zhejiang. The correlation results indicate that the Profusulinella simplex zone may extend upward to the middle and lower parts of the Huanglong Formation.

Abstract:Abstract: Lacustrine deltaic and lacustrine deposits are a major type of sedimentary facies of the Upper Jurassic Penglaizhen Formation in the Baimamiao gas field. There are usually 2-3 distributary channels entering the study area from the northwest. This delta belongs to a river-dominated birdfoot delta. Lakeshore and shallow Lake deposits are main microfacies types of lake facies. In the study area, the delta front is a dominant microfacies, and sandbody distribution is apparently controlled by underwater distributary channel, river mouth bar and distal sandbar microfacies. Finger sandbars and compound sandbars are favorable reservoirs of Members III and IV (principal gas-producing zones) of the Penglaizhen Formation. The intensive study of sandbody distribution based on the sedimentary microfacies study will be always one of the important subjects of the geological study of the Baimamiao gas field in the future.

Abstract:Abstract: Field investigations and studies indicate that climatic variation and human activities have important impacts on groundwater circulation and regeneration-evolution in the Heihe River drainage area of the northwest endorheic drainage region. Shallow groundwater in the plain is mainly recharged by modern water. 35% of it is recharged by surface runoff transformed from bedrock fissure water of the Qilian Mountains and the rest is recharged by infiltration of precipitation and melt water in the piedmont Gobi belt, both of which have a strong regeneration ability. Confined groundwater mainly originates by recharge of regional meteoric water and river water in the geological history, which has relation with modern water circulation. The influence of human activities in the middle reaches of the river is an important factor responsible for the weakening of the groundwater recharge ability, sustained lowering of groundwater level and eco-environmental degradation in the lower reaches. Therefore, the scientific regulation of the human activities in the middle reaches is the key to realizing sustainable utilization of groundwater resources in the Heihe River drainage area and effective protection of the ecological environment in the lower reaches.

Abstract:Abstract: Salt lakes are a mirror of climatic change. According to a study of geological hazards in typical salt lake districts in China and other foreign countries, the authors explain how geological hazards in salt lake districts are caused by natural agents and how mankind can avoid hazards and reduce loss on the premise that people have monitored and mastered the trend of salt lake change in advance. The climate in western China is probably turning from warm-dry to warm-moist. The authors analyze the change trend of China’s salt lakes in such climatic conditions and distinguish three types of salt lake districts (i.e. lake water rising type, lake water falling type and lake water rising and unstable type) according to the characteristics of lake water rising and shrinking. In order to conform to the climatic and lake changes in China’s salt lake districts, the authors propose to add and improve hydrological and meteorological observation stations and integrate observations with remote sensing monitoring and set up multidisciplinary and interdepartmental basic projects to monitor and study climatic and environmental changes in salt lake districts of western China in the near future. Moreover, it is necessary to build additional flood-control and drought-preventing water conservancy facilities in key salt lake districts and work out measures for ecological protection in salt lake districts. Full consideration should be given to the influence of flooding when building saltfields and implementing capital projects.

Abstract:Abstract: On the basis of an integrated analysis of the tungsten minerogenic geological and geochemical settings and geological features of tungsten and tungsten-polymetallic deposits, four types of tungsten and tungsten-polymetallic deposits in the Qilian metallogenic belt are primarily distinguished, i.e. skarn type, quartz vein type, greisen type and marine volcanic type. There are three dominant ore-controlling factors for tungsten deposits, especially large ones, in this metallogenic belt, i.e.Proterozoic and Early Paleozoic tungsten-bearing intermediate-basic volcanic-clastic rocks and carbonate rocks, composite intermediate-acid magmatic intrusions mainly of subalkaline and calc-alkaline compositions associated with orogenic processes (subductional orogeny and/or collisional orogeny) and multiple tectonic systems. Furthermore, the regional ore indications of tungsten deposits are summarized.

Abstract:Abstract:The REE content in fluid inclusions of minerals in the Koktag lead-zinc deposit was determined by the ICP-MS. The results indicate that the ore fluids are LREE-enriched and have pronounced positive Eu anomalies. Ore sulfide fluid inclusions have three REE distribution patterns, i.e. gently right-inclined type, flat type and inverted “V” type. The total REE content of the footwall rocks of the orebody is notably higher than that of the hanging wall rocks, and they have pronounced negative Eu anomalies. The ore-forming fluids have the features of multiple sources and multi-stage overlapping and show the feature of the double leaching model.

Abstract:Abstract: Study of geological features and ore composition of kaolinitic rock in coal measures of the Permian Liangshan Formation in the Renheping syncline, western Hubei, indicates that the kaolinitic rock deposit is of clastic sedimentary type and dominated by hard kaolinitic rock, with a persistent ore horizon. Kaolinite in the ore is mostly aphanitic to microcrystalline flaky textures, has a high purity (the kaolinite content is 90% to 95%) and is characterized by low Mn (<30 ×10-6) and high Ti (>0.5%). The harmful components Fe, Mg, Ca, Na, K, Mn, S and As and heavy metals elements Cu, Pb, Zn, Cd and Tl are all lower. Integrated analysis suggests that the kaolinitic rock may serve as high-quality functional kaolinite raw material and has good prospects in the rubber, plastic, coating and medicinal package industries.

Abstract:Abstract: Analysis of static geological elements of petroleum combinations in the Lile basin indicates that there are three suites of source rock in the Lile basin, i.e. lower Oligocene, Paleocene to Miocene and Mesozoic, of which the second and third suites have better hydrocarbon-generating potential. Sandstone, carbonate rocks and organic reefs are the main reservoir types, of which the sandstone reservoir is widely developed in the Meso-Cenozoic strata, while the carbonate and organic reef reservoirs are mainly developed in the upper Oligocene to Quaternary. Generally, the basin is lacking in widespread regional cap rocks with good sealing properties, but locally the cap rocks are well developed and have good sealing properties.. There are three petroleum-bearing combinations in this basin, i.e. the Mesozoic, Paleogene and Neogene petroleum-bearing combinations. The Mesozoic one has good oil-gas prospects; the Paleogene one is the most important exploration target in the basin and has the best prospect; and for the Neogene one, it is possibly difficult to form a good petroleum combination in the uplift in the central part of the basin, whereas in the depressions of the basin, especially in the southern depression, a good petroleum combination may be formed.

Abstract:Abstract: A systematic geochemical and multivariant statistical analysis of Late Cenozoic sediments (including 61 samples of surface sediments and 16 piston cores of sedimentary columns) from the East Pacific oceanic basin during the cruises DY851 and DY853 sponsored by the China Oceanic Mineral Resources Association has revealed some characteristics of geochemical evolution of the sedimentary environment in area CC of the East Pacific oceanic basin during the Late Cenozoic. It is considered that the ocean-floor spreading, distance from the East Pacific ridge, submarine geothermal flow and frequency of geothermal activity might affect the depth of the carbonate compensation depth (CCD) and the frequency and amplitude of CCD fluctuation, and therefore constrained the sedimentary environment of the study area to some extent.

Abstract:Abstract：Take for example the geochemistry of Changtai, Zhangzhou and Longhai in the downstream area of the Jiulong River, Fujian, by using the data of multi-target regional geochemical investigation, this paper discusses the method of geochemical classification of soils and proposes a scheme of classification and nomenclature and diagnostic criteria. The soils in the area is divided into four major classes: Fe-Al soil, Si-Al soil, Al-Si soil and siliceous soil, of which Si-Al soil is further divided into four subclasses: ordinary Si-Al soil, ferruginous Si-Al soil, potassic Si-Al soil and pyritic Si-Al soil. The average contents of 52 elements of various soils (siliceous soil excluded) and their uses in agriculture are investigated.