Abstract:The greatest advantage of underground engineering facilities lies in energy saving and safety. Energy-saving comes from the underground constant temperature environment, whereas safety comes from the closed environment as well as relatively insignificant artificial interference. The development of urban underground space in the hilly areas of South China has a broad prospect of utilization. This paper reports the preliminary results of the project on the development and utilization prospects of urban underground space, including the scientific problem as to how to maintain excellent ecological environment, the classification and characteristics of underground space, the investigation contents and investigation methods of usable underground space. Aimed at tackling the problems existent in the exploitation and utilization of urban underground space, the authors put forward some suggestions on the development and utilization of urban underground space in the hilly areas of South China.

Abstract:Geological conditions in Beijing plain area are extremely complicated, involving interlaced alluvial-pluvial fan and plain as well as widespread weak soil layers (e.g., made ground, soft soils), which leads to changeable shallow groundwater flow field and various geological hazards such as active faults and land subsidence, thus increasing the difficulty of underground space construction and accident probability. The weak soil layers normally have poor stability, which may cause large degrees of stratigraphic affect the anti-floating stability and impermeability of underground space, and may result in serious damages such as gushes during constructions; the active faults, which can cause three-dimensional spatial deformation with properties of tension, shear and torsion, are likely to deform underground tunnels or even lining fractures; meanwhile, the increasing ground subsidence area and subsidence rate would affect the underground tunnels constructed across the non-uniform subsidence area, and cause abnormal displacement or foundation failure. In addition, a series of geologically related environmental issues may occur during underground development, e. g., groundwater contamination, changes of groundwater flow field, or the liquefaction of sandy powder soils. In this paper, the authors investigated the influence of geological conditions on underground utilization and relevant environmental issues that arise with constructions, and elucidated the monitoring objects, index and methods for underground space development, with the purpose of contributing to geological security insurance for underground space utilization.

Abstract:North Yanqing and Fanshan Basin active fault is a significant factor for engineering design of Beijing-Zhangjiakou highspeed railway, and buried section of this active fault in Yanqing and Fanshan Basin is complicated and unclear. In order to detect the location, characteristics and activity intensity of the buried active fault, the authors used many methods, such as the controlled source audio-frequency magnetotelluric (CSAMT), shallow seismic reflection, high density resistivity and drilling exploration. The results show that the buried North Yanqing and Fanshan Basin active fault consists of two secondary faults, i.e., F2-1, F2-2, which are distributed parallelly. The trending of the tow secondary faults is N56°E, and the dip angle of them is 50~70°. Meanwhile, they are right-stepped, oblique-arranged normal faults. The burial depth of distinguishable broken point is 10m for F2-1 secondary fault and 30m for F2-2 secondary fault. F2-1 secondary fault is an active fault, its vertical activity rate has been 0.12mm/a since the Late Pleistocene. Activity of F2-2 secondary fault has been weak since the Late Pleistocene. Compared with the result of drilling exploration, the CSAMT method and shallow seismic reflection method have some advantages in exploration of bedrock interface, whereas the high density resistivity method is good at exploration of shallow loose deposits and can display more effectively broken point of fault. By means of comprehensive geophysical-drilling exploration, researchers can achieve the complementary advantages, and can reduce the uncertainty of the interpretation for buried active faults exploration.

Abstract:Special underground space (SUS) is defined as a kind of underground space with special properties in terms of spatial form, distribution and structure. According to the source, SUS is classified into two types:naturally existent space and humaninduced one. The special properties and the suitable engineering applications of different SUS types are described in this paper. In addition, the status and prospects of natural gas underground storage, carbon dioxide geological storage, compressed air energy storage, deep-well waste reinjection and radioactive waste disposal are briefly analyzed. With the development of SUS research, it is necessary to explore different SUS development and utilization methods and modes according to local conditions, which can promote the efficient use of underground space.

Abstract:Located in eastern Jiangnan orogen, the Jiuling pluton is the largest Neoproterozoic granitoid intrusion in South China. According to mineral assemblage, structure and intrusive contact relationships, Jiuling pluton can be divided into complex massif with 3 intrusion orders, followed by biotite-granodiorite, tonalite and biotite-monzogranite from early to late respectively. Among them, granodiorite are distributed most widely, followed by biotite-monzogranite, while tonalite is only distributed in a minimum area. They intruded into the surrounding epimetamorphic rocks of Neoproterozoic period. The LA-ICP-MS zircon U-Pb dating results show that the biotite-granodiorite, tonalite and biotite-monzogranite were formed in 821.6-821.6 Ma, 819.5-823.6 Ma and 820.4-824.5 Ma, respectively, which indicates that they belong to the product of contemporary magmatic activity. On the whole, however, the ganitoids tend to be younger from the southeast side to the northwest side. Besides, the dip angle of contact interface between Jiuling pluton and surrounding rocks (Shuangqiaoshan Group) is steep in the south and smooth in the north, hornfelsic belt is narrow in the south and wide in the north, and the xenoliths from the surrounding rock (Shuangqiaoshan Group) and the captured zircons also tend to decrease in size from south to north. These characteristics show that the rocks on the southeast side was eroded deeper than those on the northwest side, probably implying that, during the collision between Cathaysia plate and Yangtze plate in Neoproterozoic, the original depth of the granitic magma on the southeast side was deeper, the denudation was more intense, and the magma was formed earlier than the magma on the northwest side and gradually migrated northwestward, i.e., the origin depth of magma became shallow and the formation time became younger.

Abstract:The Taxkorgan large-scale iron metallogenic belt is located in the western part of Kunlun orogenic belt. Research on metamorphic rocks shows that the protolith of the iron-bearing strata is a assemblage of bimodal volcanic rocks-clastic rockscarbonate rocks formation. The strata have undergone widespread greenschist facies metamorphism and multi-superimposed deformation. The meta-andesite in Laobing area yielded an U-Pb ziron age of (603±10) Ma, suggesting that the eruption age of volcanic rocks is early Sinian. Combined with other age data available, the authors redefined the iron-bearing strata as "SinianCambrian Terreneuvian Maeryang Formation" (Z€₁m.), which doesn't belong to the previously defined "Paleoproterozoic Bulunkuole Group". The formation of the bimodal volcanic rocks proved that there was an extensional tectonic event in Taxkorgan area from Sinian to early Cambrian. Discrimination of tectonic setting on the metamorphic volcano-sedimentary formation indicates that the iron-bearing strata were formed in the continental margin rift. The gypsum (Ba)-iron formation was the volcanosedimentary response to the changes of "Marinoan Snowball Earth"'system after late Neoproterozoic glacial event.

Abstract:The sedimentary sources and thermal evolution of Upper Triassic of Yanchang Formation in Xunyi area of Southern Ordos Basin were studied in this paper. With the method of LA-ICP-MS, the detrital zircons ages and compositions of sandstone samples from the study area were analyzed so as to investigate the sedimentary sources. The results show that there exist six age stages of the Chang 7 detrital zircons, i.e., 225-264 Ma, 276-408 Ma, 413-458 Ma, 727-851 Ma, 1249-1749 Ma and 1868-2469 Ma, corresponding to the tectonic movements of Indo-Chinese, Hercynin, late Caledonian, Rodinia break-up, early-middle Jinning movement and Paleoproterozoic periods. Sedimentary sources are complex in the study area, and they mainly came from the western section of northern Qinling, Qin-Qi orogenic belt, West Qinling, eastern section of Qilian orogenic belt, and Tianshan-Xingmeng orogenic belt. Alxa block and northern area of the basin might have been the sedimentary sources of the study area. Paleo-current statistics indicate that the source direction was close to the southern part of the study area. Apatite fission track analysis and thermal history reconstruction were carried out, and the results confirm that the study area experienced an essential tectonic thermal event at 100 Ma in the early Cretaceous period of Late Mesozoic, which was an important period of oil and gas formation. There existed four relatively evident thermal evolution periods after that:100 to 43 Ma was a slow uplift stage and experienced partially annealing with a cooling rate of around 0.44℃/Ma; 45 to 36 Ma was a rapid uplift stage and the cooling rate came to 4.3℃/Ma; 36 to 24 Ma was another slow uplift stage with the cooling rate about 0.52℃/Ma; 24 to 17 Ma was a rapid uplift stage and the cooling rate came to 1.5℃/Ma. However, the India-Asia collision has influenced the uplift and erosion in the study area since 43 Ma.

Abstract:Aimed at exploration of provenance and basin filling records, the authors selected detrital zircons from Rigongla Formation of the Paleogene in the middle part of central Lhasa and conducted LA-ICP-MS detrital zircon U-Pb isotope analysis. The result reveals that Rigongla Formation is a kind of classic rocks which evolved from coarse to thin to coarse, with minor interbedded volcanic rocks. Judging from the sedimentary primary structure and the macroscopic section, its sedimentary environment was fan delta and shallow lake facies and fan delta. The peak age of magmatic origin of detrital zircon is concentrated in the 127-134 Ma age section. Combined with perimeter age, it is held that the provenance was from the early Cretaceous granite of NNW-trending central Lhasa block, and it was in the stage of subduction and collision uplift of the Tibetan Plateau and the stage of convergence and uplift.

Abstract:The Bangweulu Block of northeastern Zambia which consists mainly of basement and sedimentary rocks is affected by northeastern Paleoproterozoic Ubendian Belt, northwestern Mesoproterozoic Kibaran Belt, southeastern Mesoproterozoic Irumide Belt and southwestern Pan African Lufulian Belt. The basement rocks are mainly composed of schist, andesitic-rhyolitic metamorphic volcanic rocks, granitoids and other intrusions. From lower to upper part the sedimentary rocks are mainly composed of the Mporokoso Group, the Kasama Group, the Katanga supergroup and Cenozoic fluvial and lacustrine sediments. The authors systematically studied the geological characteristics of the Kasama Group, U-Pb-Hf isotopic compositions and geochemical characteristics of detrital zircon from the Kasama Group in Kasama area and obtained 32 detrital zircons U-Pb ages of the purplish red siltstone from the Kasama Group. Specifically, their ages mainly vary from (1849±23) to (1993±21) Ma, suggesting that the Kasama Group was formed younger than (1434±14) Ma and should belong to Mesoproterozoic. (¹⁷⁶Hf/¹⁷⁷Hf)_i values of 22 zircons are 0.281049-0.281618 and ε_Hf(t) values are-12.8--1.6 with corresponding TDM2 ages of 2406-3487 Ma. The REE and trace elements of sandstones from Kasama Group were analyzed. The REE have obviously negative δEu anomalies and the points mainly fall in the sedimentary area; the trace elements characteristics of sandstones show that sandstones formed in the passive continental margin.

Abstract:According to the latest high-precision 1:50000 aeromagnetic data, the authors analyzed the aeromagnetic characteristics and geological origin of the eastern section of the western Qinling orogenic belt in detail based on gravity data, inferred newly and corrected the fracture plane position, and discussed the geological significance of ore-controlling role of fractures and some typical faults. The research shows that the main factor of forming gentle negative magnetic background seems to be Paleozoic Devonian, Carboniferous, Permian, and Mesozoic Triassic carbonate rocks-sedimentary clastic rocks, whereas all kinds of widespread intrusive rocks are the main factor for complex changes and different patterns of superimposed anomaly. The whole area's basic structural framework is formed by NWW-EW trending, NNE-NE trending and NW trending deep and major faults. The deep NWW-EW trending fault was the earliest formed main fault; its aeromagnetic features seem to be the boundaries of different magnetic fields or striking magnetic gradient belts, resulting from the NS-trending subduction and collision of North China and Yangtze plate in Neoproterozoic-Triassic along Shangdan, Mianxian, Lueyang suture zone and forming a boundary of the primary tectonic units in this region. In particular, it played a decisive role in controlling polymetallic mineralization in Devonian. The NNENE trending deep and major faults might have been the product of strong intracontinental orogenic stage of Qinling Mountain in Late Triassic -Cenozoic by the vertical accretion hyperplasia action and exerted obvious cutting, traction or blocking effects on the NWW-EW and NW faults, with the continuous linear aeromagnetic gradient characterized by good torsional or magnetic field change. They served as the limit of secondary tectonic unit in the region, and played a guiding role in the migration of deep ore source materials.

Abstract:Wufeng-Longmaxi Formation in the southwestern margin of Sichuan Basin is an important field of shale gas exploration in the periphery of the Sichuan Basin. In order to study the parameter characteristics of shale reservoir and potential of shale gas resource in Wufeng-Longmaxi Formation and analyze its resource potential, the authors studied the parameters of shale by such means as geochemistry, mineral composition, scanning electron microscope, specific surface-pore diameter, and isothermal adsorption. The thickness of the organic-rich shale (TOC>1%) is generally 54-162 m, the thickness of high quality part (TOC>2%) is 26-70 m. The average organic carbon content is 2.99%-3.78%, the silicon content is 27.96% -37.0%, the feldspar content is 2.87% -4.85%, the carbonate rock content is 44.2%-54.2%, and the clay content is 9.9%-27.80%. It has the characteristics of low silicon content and high carbonate rock content and generally contains pyrite. The porosity of shale in the buried environment has a positive correlation with the gas-bearing property, and the better the gas bearing property, the higher the porosity. The main pore types are organic pore, clay mineral intergranular pore and pyrite intergranular pore. The evolution of the pores could be divided into three stages:the formation of the organic pore at the burial stage, the destruction of the organic pore at the gas reservoir destruction stage and supergene karstification. The Ro is 2.38%-3.37%, the paleogeothermal gradient is 32.57-37.55℃/km, and the terrestrial heat flow value is 84.32-97.21 mW/m². Influenced by the late Hercinian magmatic activity, the degree of thermal evolution, the paleogeothermal gradient and the terrestrial heat flow value become relatively high, and the differences between different areas could be relatively large. In Wufeng-Longmaxi Formation on the southwestern margin of Sichuan Basin, the shale deposit is favorable, the shale thickness is large, and the parameters of shale are good. The influence factors of shale gas in Longmaxi Group in this area are favorable shale deposit, good preservation condition and relatively moderate degree of thermal evolution (Ro<3.0%). Therefore, shale gas exploration should be expanded from"structural anticline"to"stable syncline"in such places as Mugan, Gaoqiao, Yongsheng and Da Gudui synclines, where there probably exists great potential of shale gas resource.

Abstract:The Karamaili ophiolite belt is located on the northeastern margin of Junggar Basin, which is a very important tectonic unit in northern Xinjiang and Central Asia area. The evolution of Karamaili oceanic basin remains controversial due to hot-debated issues on the ages and characteristics of Karamaili ophiolite. This study focuses on the Paleozoic tectonic setting in the Karamaili tectonic zone revealed by a comparative study of the Silurian-Carboniferous tectono-sedimentation on its north and south sides. To the north of the Karamaili ophiolitic belt, the angular unconformities are widely developed between Upper Silurian, Lower Devonian and underlying Middle-Upper Ordovician strata and Caledonian granitoids. The Lower Silurian strata are generally absent and the underlying Middle-Upper Ordovician strata mainly consist of andesite with greenschist facies. The Middle, Upper SilurianDevonian-Lower Carboniferous sedimentary deposition system to the north of Karamaili ophiolitic belt is similar to that to the south, including conformable contact, flat occurrence and undeveloped folds, faults and metamorphism. Anticlines or synclines are mainly of short axis, which is apparently different from strong deformation shown in the Karamaili ophiolitic mélange. Besides, pyroclastics-dominated rock associations, widely existent inclined beddings and cross-beddings and abundant kinds of animals and plants fossils indicate a littoral-shallow marine environment. Therefore, during Late Paleozoic, no ocean existed in the Karamaili tectonic zone and the oceanic basin represented by the Karamaili ophiolitic mélange had been closed before Middle Silurian.

Abstract:The Dexin and Zhazhalong Pb-Zn deposits are the representative hydrothermal vein type lead-zinc deposits in the western part of the Gangdise Ag-Pb-Zn polymetallic metallogenic belt; nevertheless, the origin of ore-forming materials of the two deposits and their genetic relation with the Narusongduo Pb-Zn deposit remain unknown. A stable isotopic method for single mineral and whole rock was used to measure the S and Pb isotopic composition of the sulfide and ore-bearing granite porphyries from the two deposits and to trace their sources of ore-forming materials. It is shown that the δ³⁴S_VCDT values of sulfide and ore-bearing granite porphyry from Dexin and sulfide from Zhazhalong range from 3.5‰ to 7.4‰, from 4.4‰ to 6.2‰, and from 2.7‰ to 8.3‰, with an average being 6.1‰, 5.7% and 5.1%, respectively; the ratios of different lead isotopes in Dexin and Zhazhalong are stable, varying in similar ranges, and the μ values of lead isotope in the two deposits vary from 9.48 to 9.82 (9.64 on average) with similar △β, △γ variation ranges and average values, which suggests that the S and Pb isotopic compositions of the sulfide are consistent with those of the ore-bearing granite porphyries in the two deposits with normal lead characteristics, granitoid origin of sulfur isotope and upper crust origin of lead isotope predominately. With comprehensive analysis of geological background and previous researches, it is concluded that the Pb-Zn mineralization in Dexin, Zhazhalong and Narusongduo Pb-Zn deposits may be products of the same metallogenic system with consistent sulfur and lead isotopic characteristics, and the granite porphyries might have supplied ore-forming materials for the hydrothermal vein type lead-zinc deposits in Zexue area.

Abstract:The ⁸⁷Sr/⁸⁶Sr curve of seawater is relatively stable in the Anisian period of Middle Triassic according to data available, which is different from the situation of frequent changes in the Early Triassic. The recovery of marine ecosystem from the endPermian mass extinction experienced an accelerating phase during the Anisian period. The Luoping biota is one of the typical representatives of the Triassic biota. The authors studied the composition and evolution of the strontium isotope in 26 carbonate samples from the standard section, i.e., Dawazi section, of the Luoping biota, in order to know the change of strontium isotope from the fossiliferous layers which contain the Luoping biota. The results show three remarkable characteristics:(1) The average value of Sr is more than 2000×10^-6 from the carbonate, which is mainly caused by the aragonite and diagenesis; (2) the low value of Mn and the Mn/Sr ratios less than 0.4 show that the these ⁸⁷Sr/⁸⁶Sr ratios can represent the composition of Sr isotope of the coeval seawater; (3) the ratios of ⁸⁷Sr/⁸⁶Sr of all samples range between 0.707969 and 0.708253, with the average ratio 0.708025. It is notable that the ratios of the ⁸⁷Sr/⁸⁶Sr are larger than the data for the same geological time published from Europe. Nevertheless, they are similar to Sr isotopic values from other areas in southern China. The authors therefore hold that the strontium isotope composition of the fossiliferous layers of the Luoping biota was not directly connected to global geological events, but affected by the regional event, such as the indosinian movement.

Abstract:The Huayangchuan uranium-niobium-lead ore deposit is a unique type of uranium polymetallic deposit in North Qinling orogenic belt. For the purpose of rapid mineral exploration, 1:10000 airborne magnetic and gamma-ray spectrometric measurement was conducted in the peripheral area to obtain high-precision airborne radioactive data. The explanation of these data is of great significance to the deployment of future exploration work. The distribution of radioactive elements shows that potassium and uranium anomalies are similarly located in the western part of the survey area, but there are no anomalies in the east. Thorium anomalies have formed an EW-trending anomaly belt at the center of the survey area, which is consistent with the ductile shear zone. The uranium anomalies are controlled by NW-and NE-trending faults. They are obviously distributed in the northeast plate with large area and high anomaly intensity, but there are no anomalies in Archean metamorphic rocks of southwest plate. The ratios of Th/K, Th/U and U/K, original U and active U were calculated in this study to understand the migration and enrichment of radioactive elements in different strata. According to the airborne gamma-ray spectrometry anomalies, ground verification work delineated three uranium mineralization zones, thus achieving the purpose of rapid mineral exploration. The result obtained by the authors can play a guiding role in the study of ore-forming process and the prospecting for uranium minerals and other strategic minerals.

Abstract:

Abstract:

Abstract:

Abstract:

Abstract:

Abstract: