Abstract:In recent years, a typical type of catastrophic ridge-top (or high-position) rockslide often occur in the strong earthquakes such as the Wenchuan earthquake. It exits out from the upper part of the steep slope and forms a volley fall with impact and crushing effect and dynamic erosion effect, causing the slide body to disintegrate and fragment, which transforms into rapid and long run-out avalanche debris or debris flow, and entraining the lower part of rock and soil mass, so that the volume increased significantly. The Xinmo landslide is this typical, it occurred at Maoxian County, Sichuan Province on June 24, 2017. The elevation of the crown of the Xinmo landslide was about 3450 m and the front edge was about 2250m. The height difference of landslide was 1200m, and the horizontal distance was about 2800 m. Its volume was up to 16.37 million m³. The landslide buried the Xinmo Village, leading to the death of 83 people. The Xinmo landslide was located on the western wing of the Jiaochang arc-shaped tectonics. Its parent rocks were the medium to thick layered metamorphic sandstone intercalated with slate in the Middle Triassic. The region was not only the epicenter area of the Diexi earthquake with magnitude 7.5 in 1933 (the intensity of the earthquake was X) but also the strong earthquake-affected area of the Wenchuan Ms8.0 earthquake in 2008 (the intensity was IX). The mountains, especially the ridge-top rockmass, were fractured/cracked due to the strong earthquakes. There were multiple groups of discontinuous structural planes in the sliding source zone, and hence the thick blocky rock mass was cracked into fragmented blocks, and the bugling area was formed at the elevation varying from 3150 to 3450 meter. In particular, there were two sets of anti-dip large joints in the sliding source area, indicating a typical failure mechanism "locked-section". Rockslide with a volume of 3.9 million m³ exited and continuously accumulated at the back of previous residual landslide. The "overload effect" triggered the slope instability under the exit and transferred into long runout channeled avalanche debris. Because the terrain was wide and the slope angle gradually decreased, avalanche debris converted to diffused one and then to scattered accumulation. The Xinmo landslide presents a typical disaster mode of the rapid and long runout initialed due to rockslide at ridge-top in strong earthquake area. A new method should be established to recognize this type of landslides. Wherever there are large-scale rockslides in steep ridge-top region, the "dynamic erosion effect" and the "overloading effect" on the previous accumulation and the talus of slope due to impact processes should be considered. Especially in the place where there is abundant groundwater along the gully, the possibility of a rapid and long runout rockslide-avalanche debris will increase. Therefore, in conducting the investigation of geological disaster, the town, village or other populated areas should be zoned as risk area on the previous landslide accumulation of slope below the exit of the rockslide at the ridge-top. The authors emphasize that, in the strong earthquake mountainous regions, the static balance method for the landslide stability should be considered, and the dynamic research on the landslide runout processes and the disaster mode should be strengthened.

Abstract:The coastal zone of China is the economic development frontier with the highest population and urbanization, critically important for the national strategy of maritime power promotion, nevertheless it is also facing the highest pressures of resources shortage and environment challenges. This paper has reviewed the last two decades' survey and research results carried out by China Geological Survey in China's coastal zone, with the purpose of assessing the advantages of geo-resources and the challenges on geo-environment as well as geo-hazards. China's coastal zone possesses very rich geo-resources which provide the foundation of sustainable and green economy development. Here are some examples:1.2×10⁴ km² tidal flat space resources can be used for future coastal spatial expansion to release the present high pressure of land resources; 2.8×10⁴ km² high quality selenium-rich farming lands and 4.1×10⁵ km² fishing grounds provide high potential capacity for green and special agriculture, fishery and marine ranching; shallow geothermal energy and geothermal water on the coastal zone can be converted into green energy equal to 4.2×10⁸ t standard coals, which will help to improve the energy consumption structure and reduce air pollution; 5.8×10⁴ km² coastal wetlands and 134 sites of geo-heritage provide high potential opportunity for ecological civilization development on the coastal zone; 90% of the coastal land spaces are geologically suitable for urbanization development and infrastructure construction, with high quality and quantity underground space resources. Nevertheless, China's coastal zone is also facing serious challenges from geo-environment, such as active faults, land subsidence, surface collapse, coastal erosion and storm surge threats, pollution in water and soil, and salt water or brine water intrusion. These challenges should be taken into account for the coastal sustainable and ecological development. The authors suggest enhancing the coastal multidisciplinary and comprehensive geological survey, establishing the integrated coastal geological models based on multiple environmental factors, geosphere-biosphere-hydrosphere interactive layers as well as multiple spatial and temporal dimensions, and revealing the distribution and causes of geohazards so as to mitigate the life and wealth losses on the coastal zone.

Abstract:The statistics of such resources as land resources, groundwater, wetland, minerals, geothermal and geological relics show that the soil quality is very good and the area of good and above-good grade possesses about 81%, in which the area of green agricultural products is 96363 km², the area of selenium-rich cultivated and garden lands is 1894 km²; and the total amount of groundwater exploitation is 188 billion m³/a, suggesting characteristics of uneven spatial distribution; the area of five biggest wetlands including Hengshui Lake is about 614 km², which has been reduced by about 35.57% in the past 30 years; the metal mineral and non-metallic mineral resources are abundant:iron ore reserves have reached 9840 million tons, the amount of copper mineral resources is 111.50 million tons, and oil geological reserves are about 2496.35 million tons; geothermal resources are rich, and the development and utilization of geothermal resources can replace 343 million tons of standard coal; geological relics are abundant, and 300 sites can be included in the Central Capital National Park Planning. Meanwhile, based on an analysis of main environmental geological problems such as active faults and earthquakes, ground collapse and fissures, landslides, land subsidence, groundwater pollution and wetland degradation in the Beijing-Tianjin-Hebei region, the authors put forward some geoscience suggestions for the urban and important infrastructure planning, wetland protection and restoration, groundwater exploitation, highquality arable land resources protection and geological relics development with the purpose of providing geological and resource safeguard for regional planning and construction.

Abstract:Carbonate rock is the material basis of karst development. It recorded some environmental changes, stored most carbon and played an important role in the primitive atmosphere and life evolution during the earth evolution. Karst covers 22×10⁶ km² of the whole world, possessing~15% of the continent surface. The effects of the karst process on climate and environmental changes are considerable, and hence the karst dynamic system (KDS) is an important component of the Earth's Surface System. In this paper, the authors made a review on the progress of the karst science in the past 30 years, which includes the conception, intention and development of the karst dynamics, geological and ecological mechanisms of driving the KDS, and some new results and findings in the fields of KDS and carbon cycle, water cycle and calcium cycle. Finally, the karst critical zone and global karst was introduced.

Abstract:Environmental geology which emphasizes the entire spectrum of human interactions with the environment and aims to maintain sustainable development of human body and geological environment, has been recognized as a major concern in geology and environment research. This paper reviewed the developing process of environmental geology discipline, and discussed the significant achievements and key issues of environmental geology research in the whole world. This provides a perspective from which to propose that environmental geology research is an urgent need for geological work with the purpose of meeting the requirements of ecological civilization construction and country development. The study of the work puts forward the development direction and priorities of research areas of environmental geology in the aspects of urban environmental geology, water resource sustainable utilization and management, geological hazard monitoring and integrated control, ecological environment protection, and earth critical zone research. It is suggested that interdisciplinary research and comprehensive research on new technology and method constitute the general trend of environmental geology development, which will profoundly influence the research progress and provide better understanding of relationships between human body and geological environment, and the problem as to how to plan better to utilize resources and protect geological environment.

Abstract:The authors investigated the origin of soil water and vertical infiltration recharge of groundwater in thick unsaturated zone of arid area based on the characteristics of water content, stable isotopes (δD and δ¹⁸O) of soil water and soluble salt ions in soil. The results indicate that the vertical profiles of stable isotopes of soil water depict a cyclic variation as well as water content and chloride of soluble salt ions for the uncultivated regions in desert and cultivated and uncultivated regions in oasis. Each cyclic variation indicates one infiltration event that has involved mixture of newly infiltrated water and existing soil water. The lower value of Cl^- content is consistent with the depleted values of δD in each cycle; δD of soil water varies from -124.10‰ to -94.44‰, which suggests that soil water originates from precipitation or snow in winter in desert and in oasis. The vertical infiltration recharge varies in the ranges of 1.29~5.53mm/a, 0.52~1.85mm/a and 0.03~0.08mm/a respectively for the cultivated and uncultivated regions in oasis and the uncultivated regions in desert.

Abstract:Tianshui is located in the faulted zone at the northern edge of the West Qinling Mountain. The active faults in the area are well developed. According to historical record, the earthquakes used to happen frequently. A large number of loess landslides have been induced in this area. Based on field investigation of the north mountains landslide group in Tianshui, the authors studied the deformation and failure characteristics of the earthquake landslide. Taking Hongqishan landslide as a typical case, combined with laboratory test results, the authors analyzed deformation mechanism of Hongqishan landslide, and then applied FLAC^3D to simulate the stability of Hongqishan landslide. The results show that the north mountain landslide group in Tianshui is induced by earthquake action; Hongqishan landslide contains two main slip belts, and it has experienced more than 3 deformation activities in history. Its evolution process is complicated and belongs to earthquake-rainfall coupled landslide; Nowadays, the Hongqishan landslide is relatively stable under the natural condition. If a strong earthquake occurs, it will cause a breakthrough of the plastic zone inside the slope, and the soil on the top of the slope will slip. The research results can provide a basis for the deformation mechanism and disaster prevention of the earthquake landslide in the potential strong earthquake area.

Abstract:It is usually believed that plutons and dikes resulted from the same magmatic activity. Deeply evolved magma invaded into the pluton from cracks. Nanzhao pluton is located in the east of North Qinling Mountain, in which a 5m wide granite dike was discovered recently. The dike has purple, porphyritic texture and the phenocrysts are quartz.The U-Pb zircon LA-MC-ICP-MS dating shows the age of the dike is (119.1±0.8) Ma, which is quite different from the age of the pluton (452.3±6.2) Ma. The Hf isotope analysis shows that the source magma maybe a mixture of juvenile crust. This result and the geochemical study indicate that the granitic dike exhibits the characteristics of I-A type granite. The similar age data, Hf isotope analysis and geochemical characteristics suggest that the dike in Nazhao pluton may have the same source magma as adjacent Funiu Mountain. According to the previous results and the analysis of regional geological background, the authors hold that the subduction of the Pacific plate occurred in the Yanshanian period, whereas the Yangtze plate and the North China plate experienced pull-apart along Qinling orogenic belt. A tectonic environment of the pull-apart was formed and, as a result, a series of faults were formed between the plate. After that, the granite magma invaded onto the surface along the faults. Most of the magma formed Funiu Mountain, while a little magma formed a dike in Nanzhao pluton, with the exchange of elements during the invasion. Therefore, the granite dike in Nanzhao pluton has tectonic implications.

Abstract:Wulashan area, located in the north part of the North China craton, has well-developed Paleoproterozoic granites, with the Nuoeryin S-type granites as the typical one. The investigation of Nuoeryin granites shows that the granites have high SiO₂ (w(SiO₂)=70.03%~75.43%), high Al₂O₃ (w(Al₂O₃)=13.04%~14.87%), and high K₂O values (w(K₂O)=5.36%~6.58%), low Mg^# (<10) and high A/CNK values, indicating that they belong to peraluminous S-type granites. They are enriched in LREE with significant differentiation between LREE and HREE (La_N/Yb_N=22.3-300.5), and REE patterns of the samples are of right-oblique type, with strong negative Eu anomalies(δEu=0.16-0.55). The primitive mantle-normalized trace element diagrams show enrichment of K, Rb, Th, Pb and depletion of Sr, Ba, Nb, Ta, P, Ti. The Nuoeryin granites have similar geochemical characteristics to the Paleoproterozic knondalites in Wulashan area and, and the reason is probably that Nuoeryin granites were generated by the knondalites anatexis while the Yinshan blocks and Ordos blocks experienced collision in Paleoproterzoic. The LA-ICP-MS zircon U-Pb ages of Nuoeryin granites are 1891±14 Ma and 1863±17 Ma, which represent the crystallization age of the Nuoeryin S-type granites, and the age is also contemporaneous with magmatic-metamorphic events in Khondalite belt.

Abstract:The Xiangshan uranium orefield is located in Le'an-Chongren border area, northeast Jiangxi Province. Its tectonic position lies on the northern margin of Luoxiao folding belt, southern side of the Qingzhou-Hangzhou suture zone between the Yangtze paleo-plate and Cathaysia paleo-plate, belonging to the southwest section of the Ganhang uranium ore belt. According to unconformity surface and features of rock association, the volcanic rocks in the Xiangshan uranium orefield should belong to the Wuyi Group. According to features of lithology and lithofacies and volcanic activity regularity, Wuyi Group can be subdivided into the Shuangfengling Formation which includes lower purple conglomerate, sandstone, siltstone, mudstone and tuff that constitute eruption-sedimentary facies and the Ehuling Formation which is composed of upper porphyroclastic lava intercalated with ignimbrite combination of outpouring-flushout facies. These two formations respectively represent the initial stage of volcanic activity and the eruption period. The SHRIMP zircon ^206*Pb/²³⁸U age estimated for the welded tuff in the bottom part of the Shuangfeng Formation is (137.5±1.4)Ma (N=13, MSWD=0.73), the dacites in middle part of the Shuangfeng Formation have the ages of (137.4±1.1)Ma (N=14, MSWD=1.3) and (137.4±1.4)Ma (N=12, MSWD=2.5), the crystal tuff in the upper part of the Shuangfeng Formation has the age of 136.4±1.1Ma (N=14, MSWD=0.49), the porphyroclastic lava of the Ehuling Formation has the ages of (135.4±1.5)Ma (N=13, MSWD=1.3) and (135.2±1.2)Ma (N=12, MSWD=0.25), which not only indicate an early Early Cretaceous age but also are in accord with stratigraphic sequence. The boundary between the Shuangfeng Formation and the Ehuling Formation is not only an interface of lithology but also an interface of lithofacies The boundary can be recognized easily in the field, and the problem concerning the division of the original Daguding Formation or the original Ruyiting Formation is thus solved. In combination with existing zircon U-Pb age of the volcanic-intrusive complex in the Xiangshan uranium orefield, the authors hold that zircon U-Pb age of the volcanic-intrusive complex cannot provide the evidence for determination of the time sequence of the volcanic-intrusive complex in the Xiangshan uranium orefield.

Abstract:In order to study the uranium source and its geological significance of the Dongsheng uranium orefield, the geochemistry, electron probe and stable isotopes of ore body and country rock from the Nalingou uranium deposit are selected. The results indicate that the original uranium content of orebody and mudstone is separately 212.45×10^-6 and 41.34×10^-6, showing strong preenrichment in the process of syngenetic sedimentation. The debris mainly comes from the adjacent Yinshan Precambrian basement, a few from late Paleozoic acid magmatic rocks, and the uranium in the process of pre-enrichment are mainly from the erosion source area of the northern basin. The REE distribution patterns of the uranium ore body and country rock is generally the same, with individual δEu positive anomaly, enrichment of LREE, and the same source of uranium. The δ¹³C_V-PDB and δ¹⁸O_SMOW values of the ore bodies are -9.7‰ and 18.9‰ respectively, and the δ³⁴S_v-CDT value of pyrite is -27.46‰, indicating that they experienced a strong organic geological process. Coffinite occur around the charcoal and scattered pyrite, and were cut through by colloidal pyrite. Uranium is enriched after diagenesis. It is believed that the pre-enrichment of uranium in the process of syngenetic sedimentation is the direct and importont source of uranium mineralization, and Dongsheng uranium ore field is the product of diagenesis of Zhiluo Formation.

Abstract:The data from 19 drill holes located in the hilly-plain region of the middle-lower reaches of the Changyuan River were systemically analyzed and, as a result, the predominant rock types of aquifers in the middle-lower reaches of the Changyuan River wetland were identified. Furthermore, based on the burial depth and development characteristics of aquifers and aquifuges, the authors divided the Quaternary aquifers in the study area into three aquifer sets, i.e., shallow, middle and deep aquifer sets. The features of spatial distribution of the aquifers in the study area were also summarized via correlation of cross sections and fence diagrams. In addition, the burial depths of groundwater tables were analyzed by using Kriging interpolation method. The results indicate that the predominant rock types of the aquifers are Quaternary sandy and gravel sediments. The profile of the shallow aquifer is like a wedged body in the downriver direction of the Changyuan River, but the thickness of the aquifer is not stable in the perpendicular direction of the river. This is in accordance with the sedimentary environment of the alluvial/fluvial fan. The results of interpolation analysis show that there are widely distributed precipitation funnels in the milled-lower reaches of the Changyuan River basin. Such a situation would impact the eco-hydrogeological process in the Changyuan River wetland park and the drainage basin. Finally, the authors discussed the recharge-discharge processes of the groundwater in the Changyuan River drainage basin and established a recharge-discharge model.

Abstract:Shallow geothermal energy is a renewable and widely distributed clean energy, it has broad prospects for development and utilization. The exploitation and utilization of geothermal energy are closely related to the division of regional geothermal field; nevertheless, there are few reports about Guanzhong basin at present. Based on regional geological and hydrogeological conditions and the classification of lithology, the authors summarized the thermal properties of rocks and soil. The influence of soil thermal conductivity and the specific heat capacity based on gray relational analysis reveal the main factors controlling the thermal conductivity and specific heat. The drying severity has the greatest impact on the thermal conductivity, whereas water content, natural gravity and porosity exhibit similar influences. The dry severity has the greatest impact on the specific heat capacity, followed by the natural gravity, whereas the water content and porosity play the weakest role. Based on the long-term observation data of downhole temperatures in the Guanzhong basin, the authors presented downhole temperature logs and temperature gradient contours. Normal temperature zone lies in the depths of 15-20 m in Guanzhong basin. The geothermal gradient is high in the middle part and low in the east and west part. The areas with large geothermal gradient include Gushi depression, Xi'an depression, Pucheng bulge and faults. The geothermal gradient of Baoji bulge, Xianyang-Liquan bulge, and Lintong-Lantian bulge is relatively small. The reasons of the differences include geological structure, groundwater activity and thermal and physical parameters of rock and soil. The heat flow in the basin was calculated using thermal physical parameters and geothermal gradient values, and the reasons which produce the heat flow difference between the shallow and the deep were analyzed. Compared with the regional geothermal background, the Guanzhong basin is hotter and its geothermal resources are abundant. The purpose of this paper is to systematically analyze the characteristics of the geothermal field in the Guanzhong basin so as to provide a basis for exploration and evaluation as well as the development of geothermal energy and to serve the construction of a good environment and society.

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