Abstract:The eastern borehole of Well SK-2, among the "two wells and four boreholes" of the deep continental scientific drilling engineering in Songliao Basin, is situated in Anda of Heilongjiang Province and was finished officially on May 26^th, 2018. Well SK-2 mainly focused on four scientific objections, i.e., paleoclimate research, resource and energy exploration, basic geological research and development of deep exploration technology. During the process if drilling which began in 2014, drilling, coring, logging, analysis of chemical element and structural exploration of surrounding areas were carried out during the SK-2 drilling engineering, and some preliminary progresses were made in scientific research:4134.8 m-long in-situ core data were acquired, and the most complete and continuous continental strata of the cretaceous were described with high resolution of centimeter-level, thus building the standard continental stratigraphic profile. Besides, evolution history of the continental facies in the Cretaceous period from scale of one million to one hundred thousand years was reconstructed for the first time, and an important climatic event of the Cretaceous was found. Apart from these achievements, evidence of Paleo-Pacific plate subduction and convergence in the deep was found, which contributes to genetic re-recognition and deep hydrocarbon exploration in Songliao basin. The implementation of deep continental scientific drilling engineering in Songliao Basin is of great significance in exploring the earth's mystery, seeking for deep energy and solving environmental problems. It is considered to be a solid step in the way of heading deep of the earth.

Abstract:This research is based on the compiled aeromagnetic map of China that almost covers whole China's continent and part of China's sea areas since 2011 and the magnetic features and fluctuation of magnetic basement reflected by these maps. Learning from subdivision idea of mainstream tectonic views, guiding by theories of plate tectonics and continental dynamics, and taking the tectonic features reflected by magnetic field as key points, in combination with gravity, remote sensing and geological data, the authors divided the tectonic setting of China into four levels. Eight first-order tectonic units include continental block domains and orogenic systems; thirty-two second order tectonic units include continental blocks, arc-basin systems and land mass; eighty-five third order tectonic units include basins, depression belts (areas), and uplift belts (areas); three hundred and thirty-two fourth order tectonic units include uplifts and depressions. This subdivision provides basic geophysical data for geological and tectonic background research and oil gas exploration. In this paper, the authors discussed the magnetic evidence for delineating boundaries of the first and second order tectonic units, and compared them with previous subdivision of tectonic units in China. The third and fourth order tectonic units were completely defined by the feature of magnetic field and fluctuation of magnetic basement. The magnetic basement depth of basins and depression areas are provided in this study, which provides the necessary technical support for oil and gas prospectors. Meanwhile, aeromagnetic anomalies show some special characteristics that are not consistent with observed geological and tectonic features, which provide raw data for discussion of tectonic features of China.

Abstract:The northeastern Pamir on the northwest margin of the Tibetan Plateau is one of the regions with strong neotectonic movement. Located in the northeastern Pamir, the Taxkorgan basin is controlled by regional Kongur tensile faulting. The strong neotectonism, high terrestrial heat and abundant underground water of the basin constitute the regional tectonic and hydrogeological conditions for geothermal resources. Tectonic investigation in Quman area of northern Taxkorgan basin indicates the NNE-striking normal faults of f₁ and f₂ were active in late Quaternary whereas the subtle EW-striking fault of f₃, whose nature was different in different structural stages, was developed only below the Quaternary sediments. These faults are the secondary fractures of Tashkorgan fault formed in different tectonic episodes. Based on the data of geological structure, age model of the section of the lacustrine deposits, EH-4 electromagnetic image and drilling, the authors hold that the NNE-striking normal faults were conduit-pipe and EW-striking thrust fault was heat conduction pathway. The atmospheric precipitation from the surrounding areas of the basin was heated by convection heating along the intersection of the different striking faults. The geothermal model involves heat source from terrestrial heat flow, gradually heating of deep circulated underground water and tectonic control of water and heat.

Abstract:Hainan Island is a relatively independent block located in the southern part of the South China Block. There exist many viewpoints for its origin. This paper is based on the systematic analysis of many pieces of evidence such as geographic geomorphology, strata, fault zone, magmatic rock, ore belt distribution, seismic exploration profile, paleontology, and genesis of three basins surrounding Hainan Island. The results show that Hainan Island was separated from Beibu Gulf and rotated about 150℃ounterclockwise from the original position to the current position. The starting time for the separation is about 65 Ma, and the main rotation drift occurred at 40-24 Ma. At present, it is still drifting toward the southeast and is accompanied by counterclockwise rotation. The genesis of Hainan Island is closely related to the collision process between the Indian Plate and the Eurasian Plate. The dynamic mechanism is that the large-scale extrusion and rotation of the Indochina block has driven Hainan Island's fission and rotation drift from South China. This study provides remote constraints for the structural evolution of the collision process. At the same time, it also has certain guiding significance for the study of the metallogenic belt in Hainan Island.

Abstract:This paper reports a new discovery of the Early Permian Bagahaer high-Mg diorite in the Meilaotewula SSZ ophiolite in Xi Ujimqin Banner of Inner Mongolia. The Bagahaer diorite occurs along the Hegenshan suture zone. The zircon U-Pb LA-ICPMS dating shows that the age of the diorite is 282±2Ma, suggesting Early Permian. The rock has high MgO (5.00%-10.94%,Mg^# 54-74), Cr (75.00×10^-6-555.90×10^-6) and Ni (26.20×10^-6-228.40×10^-6) values and low Al₂O₃ (13.48%-14.98%), K₂O (0.48%-1.61%),TiO₂ (0.28-0.76%) and P₂O₅ (0.080%-0.160%) values. The diorite is enriched in K, Rb and Sr large ion lithophile elements, and depleted in Nb, Ta,Zr, Ti and P high field strength elements. The total REE is low (25.16×10^-6-83.57×10^-6). Rare earth curve is of flat slightly right pattern. All of the geochemical characteristics indicate that the Bagahaer pluton belongs to high-Mg dioritoids and island-arc magmatite generated along a subduction zone, similar to features of sanukitoid. Combined with the temporal and spatial distribution characteristics of the boninite and adakite within the Meilaotewula SSZ ophiolite, it is suggested that, in Early Permian, the Paleo-Asian Ocean was not closed in the study area but was at its subduction stage. It is inferred that the high-Mg diorite might have been derived from partial melting of the mantle wedge metasomatised by subducted oceanic crust+sedimentderived siliceous melts during the Paleo-Asian Ocean subduction.

Abstract:Located in the south of Yili basin, the Western Tianshan Orogen belt played an essential provenance role in the formation of Yili basin. This paper focused on the dominant monzonitic granites of Qiongbola area, which is situated on the northern margin of Western Tianshan belt. The authors investigated their U-Pb geochronology by using zircon and geochemistry. These granites are Early Carboniferous intrusions, which mainly include three stages, which are (351.2±3.0) Ma, (339.7±2.2) Ma, and (330.5±2.2) Ma, respectively, according to the LA-ICP-MS U-Pb dating results of zircons. The whole-rock U-Pb dating of ore-bearing sandstone of 511 U deposit yielded an isochron age of 308±26Ma, suggesting that these granites were probably the main provenance for orebearing sandstone. The SiO₂ content of these granites varies from 70.15% to 73.38%, the K₂O+Na₂O values vary from 6.32% to 7.88%, and the A/CNK ratios vary from 0.82 to 1.03, suggesting that these intrusions are high-K calc-alkaline granites. The LREE values are from 50.19×10^-6 to 87.92×10^-6, suggesting relatively more enriched than HREE which are 9.44×10^-6 to 12.08×10^-6, with δEu being commonly 0.71 to 0.97. In addition, these granites are commonly rich in Rb, Th, K, Pb, and Sr and depleted in Nb, Ta, Zr, P, and Ti. The Sr isotope ratios range from 0.7050 to 0.7082, the ¹⁴³Nd/¹⁴⁴Nd ratios vary from 0.512217 to 0.512254, and the ε_Nd(t) vary from 0.3 to 1.0, with model ages being from 1010 to 1098 Ma. These geochemical results highly suggest that these intrusions were the mixture of mantle-derived basaltic and crustal molten magma, and were formed in the syn-collision tectonic environment.

Abstract:The Datonggou granitic plutons, outcropped in the middle part of Altun Mountains, are principally composed of monzonite granite. The LA-ICP-MS zircon U-Pb isotopic dating indicates that the Datonggou monzonite granite was emplaced at (353.7±1.1) Ma. They have high-K cal-alkaline and strong peraluminous features (SiO₂=74.5%-76.2%, Al₂O₃=12.62%-14.15%, (Na₂O + K₂O)=7.71%-8.29%, K₂O/Na₂O=0.9-1.22, A/CNK=1.0-1.19). The Datonggou granitic plutons are rich in large ion lithophile elements (LILE) and depleted in high field strength elements (HFSE) with a clear negative Ba, Nb, Sr, P, Ti anomaly. REE distribution patterns show strong negative anomaly of Eu (δEu=0.03-0.59) and distinct enrichment of LREE relative to HREE. The geochemical characteristics of trace elements indicate that the rocks were formed by partial melting of variable hybrid sandstone and variable mudstone from the upper crust. The partially melting temperature calculated by whole rock Zr thermometer is 722-745℃ and pressure is 0.8-1.6 GPa. Combined with the data from the Altun Mountains, it is held that the Datonggou granitic plutons in middle Altun Mountains might be related to the delamination of deep blocks under the Altun orogen.

Abstract:The Qinling Group is the main component of the Qinling microcontinent, and the accurate determination of its age is of great significance for the study of the tectonic evolution of the Qinling orogenic belt. This paper presents zircon LA-MC-ICPMS U-Pb geochronologic data of the albite two-mica schist from Yanlinggou Formation and the sillimanite two-mica monzo-gneiss from Guozhuang Formation of Qinling Group in Wulichuan-Zhaigen area. The dating results of the magmatic core of detrital zircons from albite two-mica schist show 5 age groups mainly, i.e., 545-551 Ma, 754-778 Ma, 900-1000 Ma, 1340-1830 Ma and 2300-2500 Ma, in which the 900-1000 Ma group exhibits most obvious peaks of detrital zircons, and an inconsistent line of the upper intersection point of (2478 ±25) Ma can be fitted to a part of data points. The sillimanite two-mica monzo-gneiss ages are mainly concentrated in 1400-1800 Ma, with only four data points being in the range of 1134-1243 Ma, and the youngest magmatic core of detrital zircons is (1103 ±6) Ma. According to the data, the authors hold that the age of Yanlinggou Formation was younger than 900 Ma, and older than 438 Ma pluton of Wuduoshan. Guozhuang Formation is mainly formed during late Mesoproterozoic, younger than 1122 Ma, and older than 962 Ma Neoproterozoic granitic rocks. The sedimentary material of Yanlinggou Formation complex was mainly from Neoproterozoic granitic rocks and Proterozoic continental crust, with a little from Guozhuang Formation. Most sources of Guozhuang Formation were from the late Paleoproterozoic to Mesoproterozoic granitic continental crust. Yanlinggou Formation and Guozhuang Formation were formed in different periods, and there was a discontinuity between them. Their sedimentary materials were also different, and even a small amount of material of Yanlinggou Formation was postredeposition material from Guozhuang Formation. The two formations are different tectonic sheets. Therefore, the Yanlinggou Formation should be separated from the Qinling Group.

Abstract:There are various genetic models about the concentrically zoned igneous complexes. In order to investigate the genesis of the concentrically zoned Alatage igneous complex in central Tianshan Mountains, the authors studied the origin of dark coloured enclaves within the complex and their magmatic evolution in this paper. The enclaves are extremely unevenly distributed, and are concentrated in the southeastern part of the more acidic granitoids within the complex. Most of them are rounded or sub-rounded, with a microlithic to fine-grained texture. Some enclaves contain feldspar phenocrysts that were derived from the host rocks. Based on an analysis of major and trace elements, Sr-Nd isotope, and U-Pb geochronology of individual zircons of the dark coloured enclaves, it is suggested that they are mainly dioritic and granodioritic enclaves and belong to high-K calc-alkaline or K-rich basalt series, with low SiO₂ (56.72%-61.80%) and high K₂O+Na₂O (8.12%-10.55%) content. Their Rittman index is 4.59-4.85, with enriched rare earth elements. The covariance diagrams of the major and trace elements of the enclaves and host rocks show varying degrees of linear relationships, and the curve patterns of REE and trace elements of the enclaves and host rocks are similar, which indicates that there are both similarities and differences in the geochemistry of the enclaves and host rocks. These characteristics indicate that the genesis of the circular granitoid complex is related to magma mixing of at least two types of magma. The enclaves have relatively low (⁸⁷Sr/⁸⁶Sr)_t ratios (0.705204-0.705914), and positive ε_Nd(t) values (1.65-2.57), which indicates that the primary magma of the enclaves is a mantle-derived basaltic magma. The relationship between the enclaves and host rocks suggests that mafic magma was injected into acidic magma to result in magma mixing. The results obtained by the authors provide important evidence for the multiple origins of the concentrically zoned Alatage igneous complex that was generated by magma mixing between crust-sourced acidic magma and mantle-derived mafic magma.

Abstract:The Cuonadong dome, which is firstly reported in this study, is exposed as an east-southern important part of the North Himalayan gneiss domes (NHGD),. The Cuonadong dome is located in the southern part of the Zhaxikang ore concentration area, which is divided into three tectono-lithostratigraphic units by two circle faults around the dome, which is geometrically from upper to lower (or from outer to inner) in order of cap rocks, decollement system and core, with the outer fault being upper detachment fault and the inner fault being lower detachment fault. The Cuonadong dome is a magmatic orthogneiss and leucogranite mantled by orthogneiss and metasedimentary rocks, which in turn are overlain by Jurassic metasedimentary and sedimentary rocks. The grades of metamorphism and structural deformation increase towards the core, which is consistent with the low to high degree metamorphic schist, tourmaline granitic biotite gneiss, garnet mica gneiss, and mylonitic quartz mica gneiss of the Ridang Formation. Their typical metamorphic minerals include garnet, staurolite, sillimanite and kyanite. The Cuonadong dome has preserved evidence for four major deformational events:southward thrust, early approximately N-S extensional deformation, main approximately E-W extensional deformation, and late collapse structural deformation around the core of the Cuonadong dome, which are consistent with four groups of lineation, respectively. The form of the Cuonadong dome resulted from the main E-W extension which resulted from eastward flow of middle or lower crust from beneath Tibet accommodated by northward oblique underthrusting of Indian crust beneath Tibet. The establishment of the Cuonadong dome has enhanced and enriched the significance of the E-W extension of the NHGD, which is further divided into two structural dome zones according to the different extensional directions:approximately NS extensional North Himalayan gneiss domes (NS-NHGD) and E-W extensional North Himalayan gneiss domes (EW-NHGD).

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Abstract:The Nannihu molybdenum polymetallic orefield is an important production area of Mo (W) Pb, Zn, Ag polymetallic ore resources in China, which includes 3 proven super large molybdenum (tungsten) deposit, 3 large molybdenum (tungsten) deposits, and more than 10 medium and large Pb Zn Ag (Au) deposits. The orefield has superior geological metallogenic conditions and deep prospecting potential. The depth of the existing mineral exploration is mainly 500m to a shallow range, and the deep (500-2000 m) prospecting work is basically blank. It is necessary to use the integrated geophysical method to study the metallogenic regularity and predict the new mineral resources. By studying the geological and geophysical characteristics of the area and the geophysical anomalies of the typical deposits, significant research results have been obtained:(1) The intrusion model of the concealed rock mass is established, which is closely related to the mineralization. The whole concealed rocks are divided into three zones from south to north; the depth of the top of the buried rock is 0~800 m, and the distribution area is about 125 km²; the depth of the top of the buried rock is 0.8-1.5 km, and its distribution area is about 158 km²; the depth of the top surface of the buried rock is 1.5-3 km, and its distribution area is about 233 km². (2) The three-dimensional metallogenic model, which is divided into four spatial metallogenic regions from the surface according to the different spatial locations of mineralization, and integrated geophysical prospecting model (the geophysical field marks of the concealed rock mass, the upper zone of the concealed rock mass, the kupola and the porphyry, the ore bodies and the mineralized bodies) are established. (3) It is pointed out that the concealed rock top belt and the kupola above it, dikes, apophyse and porphyry are favorable sites of mineralization. (4) Ore prospecting potential is predicted; the methods for prospecting of tungsten and molybdenum lead-zinc-silver gold mineral deposits are summarized. The research results have important significance for deep prospecting in this area and similar mining areas.

Abstract:The Xindigou gold deposit in Inner Mongolia is a medium-sized greenstone type gold deposit but belongs to crisis mine which needs replaceable resources, and hence it is of great significance to evaluate the deep resources. Based on the prospecting and genetic mineralogy theory, the authors analyzed the thermoelectric characteristics of pyrites at different elevations and orebodies using the microscope, electron probe and thermoelectric instrument. Some conclusions have been reached:The pyrite crystals are mainly characterized by cubic, pentadododecahedral and poly-type in the Xindigou deposit, the thermoelectric properties of pyrites, ranging from -331.10 to 340.20 μV·℃^-1, are mainly of the N type, which accounts for about 80%. The ore-forming temperature of the deposit ranges from 250 to 340℃, indicating that the deposit is a medium temperature gold deposit. The thermoelectric parameters of pyrite vary greatly; the degree of denudation varies from 67.96% to 74.31%. According to the spatial distribution of the thermoelectric parameters of the pyrite and the denudation of the orebody, Youlougou orebody may be located at the bottom, and may have a small-scale extension toward the depth. Drill hole ZK106 of Xiaoxigou or body has a better exploration prospect with largescale extension, and drill hole of ZK102 of Xiaoxigou orebody has more potential than ZK2802 of Dahanqing orebody in terms of exploration prospect in the depth. Furthermore, comprehensive results suggest that the deep deposit has good prospecting potential.

Abstract:Hyperspectral technology of drilling cores, which can provide geological information of drilling core, is a new research direction. Alteration of drilling cores is developed in the Baiyanghe uranium deposit, and the study of alteration can provide better reference for deep uranium exploration. In this paper, the spectra of eight drilling cores in the Baiyanghe deposit were measured and analyzed by FieldSpec4 visible-shortwave ground-based infrared spectrometer, and the results show that the hydrothermal alteration mineral assemblage of the drilling cores has three types of obvious zonation features, which is named "the upper is high, the bottom is low and the middle is transitional", In detail, Al-poor muscovite + a little hematite, limonite and montmorillonite assemblage is in the upper part of the drilling core, intermediate Al-content muscovite + Al-poor muscovite + a little hematite, limonite, montmorillonite and carbonate assemblage is in the middle, Al-rich muscovite + chlorite and carbonate assemblage is at the bottom. The varieties of muscovitès Al-OH absorption peak reflect the hydrothermal activities of the deposit, whose feature is that the relatively higher temperature, higher pressure and more acidic hydrothermal fluid is in the depth, and things are just the opposite in the upper part. The characteristics of three types of zonation and hydrothermal activities show that the Baiyanghe uranium deposit probably has obvious hydrothermal ore-forming background and uranium mineralization is located in the transition zone, which may be a favorable site for uranium mineralization and possible hydrothermal/mineralization centers. The transition zone develops hematite, intermediate Al-content muscovite, and Al-rich muscovite, which may be closely related to uranium mineralization. These data can provide reference and information for the deeper exploration.

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