2019 Vol. 25, No. 2

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2019, 25(2): .
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APPLICATION AND TREND OF NUMERICAL SIMULATION IN DYNAMIC STUDY OF OROGENIC BELT IN CHINA
CHEN Zhenkun, SU Jinbao, LU Yi
2019, 25(2): 151-165. doi: 10.12090/j.issn.1006-6616.2019.25.02.014
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Numerical simulation provides an effective tool for the study of orogenic dynamics. Depending on the different dynamic problems in orogenic belts, the researchers have carried out various simulations, which is difficult to judge their advantages and disadvantages. With that in mind, based on the review and analysis of the orogenic belt dynamics in China by numerical simulation, the numerical simulation methods and results of orogenic belt dynamics are summarized, and the prospects and the future research direction are presented. At present, numerical simulation technology has made remarkable progress in the study of orogenic dynamic simulation in China, but there are still some shortcomings compared with foreign orogenic belt research, such as the simulation study of the Pacific plate subduction to Eastern China. This requires enhancing the contrast between the Ocean-Continent subduction simulation results and the actual geology. Meanwhile, the application of Multi-field coupled 3D models and the combination of high-precision simulation and advanced solution methods is the trend of orogenic dynamics simulation research.
METHOD FOR DETERMINING ELASTIC PARAMETERS FOR THE PREDICTION MODEL OF SHALE TRANSVERSELY ISOTROPIC GEOSTRESS
TIAN He, ZENG Lianbo, SHU Zhiguo, BAO Hanyong, XU Xiang, MAO Zhe, WANG Xiaoyao
2019, 25(2): 166-176. doi: 10.12090/j.issn.1006-6616.2019.25.02.015
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The distribution of geostress constitutes the geological basis for shale hydraulic fracturing, which is an important way of shale gas exploitation. The calculation of shale geostress based on the transversely isotropic model needs to obtain five elastic parameters C11, C33, C44, C66, and C13, among which C11 and C13 can not be obtained directly from the logging data, and prediction models need to be established for the estimation. Based on the measured ultrasonic data of the Longmaxi Formation shale in the southeast of the Sichuan Basin, five kinds of prediction models for elastic parameters were established. They could be divided into two types by whether or not the Stoneley wave are used. Type Ⅰ is the ANNIE, MANNIE1 and MANNIE2 models with Stoneley wave, and type Ⅱ is the MANNIE3 and V-reg models which lack for Stoneley wave. The rationalities of stiffness tensors predicted by different models were compared and evaluated. Among these models, model MANNIE1 has the smallest deviation and the best effect in type Ⅰ models. Elastic parameter calculated by V-reg model makes more deviation compared to MANNIE1, but type Ⅱ models has wider range of application to get all three parameters C11, C66 and C13. The elastic parameters determined by V-reg model are applied in the calculation of geostress in Jiaoshiba area. The error between calculated gestress and measured value is less than 10%, which can reflects the actual formation more accurately.
THE QUANTITATIVE PREDICTION OF STRUCTURAL FRACTURES IN ORDOVICIAN RESERVOIR IN YU-BEI AREA, TARIM BASIN
ZHANG Jibiao, LIU Shilin, DAI Junsheng, ZHANG Zhongpei
2019, 25(2): 177-186. doi: 10.12090/j.issn.1006-6616.2019.25.02.016
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Based on the finite element method, the numerical simulation of the paleo tectonic stress field in different fracture development stages in Yu-bei area was carried out. Further more, according to the rock failure criterion and strain energy conservation, the fracture parameters were calculated based on the quantitative relationship between the stress and fracture. The results show that the fractures in Ordovician reservoirs in Yu-bei area are mainly structural fractures, and their development are obviously controlled by the structural position. The structural fractures mainly developed in late Caledonian-early Hercynian and late Hercynian period. The fracture density is dominant between 0.04~0.2 strip/m in late Caledonian-early Hercynian, and between 0.2~2.0 strip/m in late Hercynian. The stress in late Hercynian has an obvious influence on the early fractures. With the influence of structural movement in late Hercynian, the aperture increased obviously by 78.6% on average. The fractures developed both in late Caledonian-early Hercynian and late Hercynian have high density and aperture, which are more favorable for hydrocarbon migration and accumulation as potential oil and gas enrichment area.
ORE-FORMING STRUCTURE ANALYSIS OF THE LIANGYAN LEAD-ZINC MINING AREA IN NORTHWESTERN GUIZHOU DEPOSIT CONCENTRATION DISTRICT, CHINA
WANG Mingzhi, HAN Runsheng, ZHOU Wei, SONG Danhui, LUO Da, ZHOU Jianfei, WU Ruilin
2019, 25(2): 187-197. doi: 10.12090/j.issn.1006-6616.2019.25.02.017
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The Liangyan Pb-Zn deposit is one of the typical deposits in the northwest Guizhou Pb-Zn polymetallic ore-concentrated area in the Sichuan-Yunnan-Guizhou Triangle area (SYGT). Based on detailed analysis of the ore-controlling structures of the three levels at DaJie ore section by Geological Mechanics Theory and Method of Ore-field, combining comprehensive analysis of regional structure, this paper focuses on the prospecting direction in the deeper part of this area. The analysis shows that at least three tectonic stages developed in this area, and the corresponding principal compressive stress changes successively from NW to NE, then to EW. Ore bodies controlled by different mechanisms occurred in different parts of the fault. It is concluded that the deposit was controlled by NW-SE-trending compressive stress processes in the ore-forming period, which is coincident to the tectonic stress field of the northeast Yunnan HZT deposit concentration district. This new understanding is different from the previous opinion that the Yadu-Mongdong metallogenic belt in the metallogenic period was controlled by NE-SW-trending compressive stress processes. The NW-SE-W compression is basically a tectonic event after the mineralization.
STUDY ON OCCURRENCE REGULARITY OF COAL-BASED GRAPHITE IN KEKENG MINING AREA IN ZHANGPING, FUJIAN PROVINCE
DING Zhengyun, CAO Daiyong, WANG Lu, PENG Yangwen, LI Yang, CHEN Quanlin, DENG Ruijin, LIN Xiaoyan
2019, 25(2): 198-205. doi: 10.12090/j.issn.1006-6616.2019.25.02.018
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Zhangping Kekeng mining area is located in the coal-bearing belt in the central part of Fujian Province. It contains abundant high-metamorphic anthracite and has good prospects for coal-based graphite resources. It is an important graphite metallogenic area in Fujian Province. In order to find out the occurrence regularity of coal-bearing graphite in Kekeng mining area, the structural evolution characteristics of coal-forming graphite, the mechanism of coal-forming graphitization and the controlling factors were studied by X-ray diffraction, Raman spectrum, combined with magmatic activities and tectonic movements in the mining area. The results show that coal-based graphite is the product of magmatic heat and tectonic stress. In the process of coal-forming graphitization, the high temperature generated by magmatic heat promotes the interconnection and lateral growth of aromatic layers, and tectonic stress is beneficial to the preferential orientation and orderly stacking of aromatic layers. Under the influence of temperature, stress and other factors, the defects of carbon interlayer structure disappear gradually, graphite lattice forms and micro-phase changes; eventually a relatively perfect graphite structure is formed. The influence of tectonics and magmatic intrusion on coal-forming graphitization is clarified. Three-grade ore-controlling fault zones and three metamorphic belts are classified, which are tectonic dynamics-magmatic thermal metamorphic belt, magmatic thermal-tectonic metamorphic belt and tectonic dynamic metamorphic belt. The coal-based graphite in the Kekeng mining area is produced in tectonic dynamics-magmatic thermal metamorphic belt, and the ore-bearing layer is close to the rock mass with a monoclinic layered and layer-like distribution with approximately E-W strike; however, the distribution of ore deposits is not only controlled by rock mass but also controlled by three-grade ore-controlling faults in space.
CHARACTERISTICS AND INFLUENCING FACTORS OF CARBONIFEROUS VOLCANIC RESERVOIRS IN HASHAN AREA, NORTHWESTERN MARGIN OF THE JUNGGAR BASIN
YU Hongzhou
2019, 25(2): 206-214. doi: 10.12090/j.issn.1006-6616.2019.25.02.019
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As important exploration targets at the northwestern margin of the Junggar basin, Carboniferous volcanic rocks formed under the background of continental island arc and oceanic island arc. In order to study the development and controlling factors of volcanic reservoirs in the Hashan area, based on outcropping observation, through studying core, ordinary and cast thin sections, scanning electron microscope and other means, combined with FMI analysis, the petrological characteristics, reservoir characteristics and influencing factors of volcanic rocks were explored. It is believed that Carboniferous volcanic rocks are mainly composed of five lithological types, which can be classified into two classes, including lava-formed rocks, such as basalt and andesite, and pyroclastic rocks, such as volcanic breccia, tuff and sedimentary tuff. There are 16 types of reservoir space, which can be classified into three larger types that are corrosion-fracture type, fracture-corrosion type and corrosion type. Lithology and lithofacies are the internal factors affecting the reservoir, while weathering, leaching and tectonics are the external factors. Weathering and leaching mainly occur under the weathering crust, the interface of volcanic eruption cycles and the interface of eruption periods. Moreover, a large number of fractures are generated by tectonism, which can not only improve the percolation performance of reservoirs, but also effectively increase the storage space. The weathering crust at the convergence zone of faults and the development areas of volcanic breccia, tuff and andesite at the interfaces of eruptive cycles and periods are favorable reservoir areas. This study provides a basis for predicting the favorable reservoir distribution of carboniferous volcanic rocks in the Hashan area and a theoretical support for exploration and deployment.
DYNAMIC ACCUMULATION PROCESS OF COAL-FORMED GAS IN WENLIU AREA, DONGPU DEPRESSION
HU Hongjin, JIANG Youlu, LIU Jingdong, ZHAO Kai, MU Xiaoshui
2019, 25(2): 215-222. doi: 10.12090/j.issn.1006-6616.2019.25.02.020
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The Wenliu area is one of the typical coal-formed gas accumulation zones in the Bohai Bay Basin. With the deepening of exploration, the fine characterization of the coal-forming gas accumulation process in this area still needs to be improved. The fluid inclusion technology was used to analyze the coal-formed gas accumulation date in Wenliu area. Based on the analysis of fault activity, the evolution characteristics of the transport system in the study area were determined. The gas-fluid inclusion abundance (GOI) test were used to analyze the gas preservation conditions, and finally the process of coal-formed gas accumulation in Wenliu area was carried out. The results show that the Wendong fault is a gas source fault in the study area, and its hydrocarbon supply conditions can be characterized by the Fault Transport Efficiency Coefficient (FTEC). The study area has superior gas supply conditions; the coal-formed gas in Wenliu area originates from the adjacent deep sag zone, and vertically transports along the Wendong fault to the Carboniferous-Permian and the Es4 sandstone reservoirs in the trap during the sedimentary period of the Dongying Formation. Small amount of the coal-formed gas loss occurred during the tectonic uplifting movements in the late sedimentary period of the Dongying Formation.
A NEW METHOD FOR FRACRABILITY EVALUATION IN DEEP AND TIGHT SANDSTONE RESERVOIRS
ZENG Zhiping, LIU Zhen, MA Ji, ZHANG Chunlei, LI Jing, SUN Luning
2019, 25(2): 223-232. doi: 10.12090/j.issn.1006-6616.2019.25.02.021
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Fracrability evaluation is the basis for the optimization of fracturing level and the evaluation of productivity after fracturing. The tight sandstone reservoirs in block 4 in central Junggar Basin are buried deep and poor in physical property, and it is urgent to improve the industrial productivity by fracturing. Therefore, the fracture property of the Jurassic tight sandstone of Dong 2 well north area is studied as an example. Based on the experimental data of the rock triaxial test, the fitting formula of fracture energy density and elastic modulus of tight sandstone is established. Brittleness index of rocks at different depths in the study area is determined by mineral composition method and elastic modulus-Poisson ratio method.The fracture development index of different depths in the study area is determined by the criterion of rock fracture. Fracture energy density is used to characterize the fracture toughness of tight sandstone, and the fracture development index is used to characterize the development degree of natural fractures. Considering the influence of rock brittleness, fracture toughness, in-situ stress and development degree of natural fractures, the weight of each parameter is calculated by analytic hierarchy process, and a new quantitative fracrability evaluation of deep and tight sandstone reservoirs is established. The results show that when the fracrability index is greater than 0.55, the reservoir can be fractured well, when the fracrability index is between 0.50~0.55, the fractured reservoir is moderate, and when the fracrability index is less than 0.50, the fractured reservoir is poor. In the study area, the optimal fracturing horizons of Well D7 are 4145~4160 m, 4470~4480 m, 5290~5330 m, Well D8 are 5120~5330 m, 5350~5365 m, and Well D701 are 3900~3910 m, 4430~4440 m, 4455~4465 m, 5125~5135 m.
STABILITY INVESTIGATION AND TREATMENT EVALUATION OF SLOPES IN THE EASTERN TIBET SECTION OF THE SICHUAN-TIBET HIGHWAY
YE Tangjin, XIE Qiang, WANG Ying
2019, 25(2): 233-239. doi: 10.12090/j.issn.1006-6616.2019.25.02.022
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The eastern Tibet section of Sichuan-Tibet Highway is always suffered by unstable slopes even after years of repeated governance. In order to solve this urgent problem, a good knowledge of all slope data and slope treatment status of this area must be obtained. Totally 204 slopes along the Highway have been investigated in detail for three years. The present situation of slope treatment was counted, and its characteristics were analyzed distinguish by soil and rock landslides. Based upon data, factors causing slope instability were analyzed, and slope stability evaluation model was established using random forest method. The importance of influencing factors for slope stability and stability of all slopes were calculated by the model, and the model test showed that the accuracy was over 94.44%. The study results of this article could be used in the engineering management of highway works department. Also, suggestions are proposed on the management of highway slope based on the field investigation.
SIMULATION OF THE CRACK PROPAGATION FOR THE MODEL WITH A HOLE UNDER DIFFERENT CONFINING PRESSURES BASED ON A CONTINUUM-DISCONTINUUM METHOD
BAI Xueyuan, WANG Xuebin, MA Bing, LU Weinan, ZHU Mingze
2019, 25(2): 240-248. doi: 10.12090/j.issn.1006-6616.2019.25.02.023
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To effectively simulate the transition process from continuum medium to discontinuum medium, a continuum-discontinuum method was developed, which is a combination of the Lagrangian element method, the deformational discrete element method and the fictitious crack method. In this method, the cracking along the diagonal line of the quadrilateral element is taken into consideration. Deformation-cracking processes of the models with a hole under different confining pressures were simulated through this method. The number of tensile and shear crack segments was calculated, and the maximum principal stresses for some elements were monitored. The following results are found. At the low confining pressure, the initial tensile cracks first appear at the roof and floor of the hole, and then they extend towards the top and bottom of the model respectively. At both sides of the initial tensile cracks, remote tensile cracks appear in tensile stress concentration zones, and then shear cracks appear at both sides of the hole; finally, shear cracks go through the model. At high confining pressure, few remote tensile cracks are found, and the dividing line between the stage of remote tensile crack propagation and the stage of shear crack propagation is not clear. The decrease of the maximum carrying capacity is due to shear crack propagation at the both sides of the hole. With an increase of the confining pressure, the number of timesteps of the initial tensile cracks increases, while that of the remote tensile cracks at both sides of the initial tensile cracks decreases and it takes more time for them to appear.
STRATIGRAPHIC GEOCHRONOLOGY OF ACX02 BOREHOLE IN THE MIDDLE AND LOWER REGION OF THE YONGDING RIVER, THE NORTH OF THE LANGGU DEPRESSION
LI Ruijie, ZHAO Yong, WEI Bo, SUN Yonghua, WANG Qiang
2019, 25(2): 249-256. doi: 10.12090/j.issn.1006-6616.2019.25.02.024
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The establishment of quaternary stratigraphic chronology framework is of great significance to the study of regional stratigraphic correlation and paleogeographic environment evolution. The structural construction and lithological composition characteristics of the 378m core sediments of the ACX02 borehole in Houwanggezhuang village in the north of the Langgu depression in the middle and lower reaches of Yongding river were analyzed. Using methods of well logging, paleomagnetism, AMS14C and OSL dating, detailed stratigraphic division, study of sedimentary facies, and establishment of stratigraphic chronology framework were carried out for ACX02 borehole profile. The results show that:the core records the sub-time of positive polarity of bujong, jaramillo, ordovi and gauss; The strata from old to new are:the lower pleistocene (Qp1) is dominated by fluvial and flood plain facies with a bottom boundary of 260 m; the middle pleistocene (Qp2) is dominated by limnetic sedimentary with a bottom boundary of 76.7 m; the upper pleistocene (Qp3) is dominated by fluvial facies with a bottom boundary of 59.7 m; the holocene (Qh) is dominated by flood plain facies with a bottom boundary of 15.45 m.
ESR DATING OF THE BASUO FORMATION IN THE NORTHEASTERN HAINAN ISLAND AND ITS TECTONIC SIGNIFICANCE
XIA Mengmeng, WANG Chaoqun, HU Daogong, ZHAO Xitao, JIA Liyun, WU Huanhuan, LYU Tongyan
2019, 25(2): 257-266. doi: 10.12090/j.issn.1006-6616.2019.25.02.025
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The Basuo Formation is an important stratigraphic unit in late quaternary and forms the main sedimentary formation of the second-level terrace (T2) in northeastern Hainan Province. Its formation age is of great significance to the study of paleoenvironmental evolution and crustal movement in the study area since late quaternary. In order to precisely define the age of this formation, we conducted a systematic research of the Basuo Formation distributed in Zhuxi River and Gusanjiang River in northeastern Hainan by using the method of Electron Spin Resonance(ESR) and acquired the geochronological data. The results show that the Basuo Formation was formed during 64.36~18.40ka BP, and the sedimentary age corresponds to the last glacial stage of MIS4~MIS2; The river incision and the formation of T2 terrace, to some extent, reflect the frequent fluctuation of sea level and the intermittent uplift of crust in the northeast of Hainan during this period; moreover, the old red sands in the strong sandstorm action zone of modern coasts is the aeolian accumulation of contemporaneous and heterogeneous with the Baduo formation, which should be distinguished from the Baduo formation.
MINERAL COMPOSITION AND PLATINUM-GROUP ELEMENTS OF THE NEOPROTEROZOIC WANGJIANGSHAN LAYERED INTRUSION AT THE NORTHERN MARGIN OF THE YANGTZE BLOCK: IMPLICATIONS FOR THE PROCESSES OF MAGMA EVOLUTION AND TECTONIC SETTING
WANG Yan, WANG Mengxi, JIAO Jiangang
2019, 25(2): 267-285. doi: 10.12090/j.issn.1006-6616.2019.25.02.026
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The Wangjiangshan layered intrusion occurs in the Neoproterozoic Hannan arc at the northern margin of the Yangtze Block, and it is composed of ultramafic to intermediate rocks from the bottom to the top. The lower zone is mainly composed of pyroxenite and troctolite, the middle zone is olivine gabbro and gabbro, and the upper zone is gabbro and diorite. This study focuses on olivine noritegabbro, noritegabbro and gabbro in the middle zone. The compositions of olivine, pyroxene and bulk-rock suggest that the Wangjiangshan intrusion was derived from subcontinental lithospheric mantle which was mainly composed of spinel lherzolite and metasomatized by subducted slab-derived fluids. The parental magma of the middle zone was tholeiitic basalt with high oxygen fugacity, inferring from the in-situ compositions of ilmenite-magnetite mineral pair. The shallow magma chamber was about 12.9 to 18 km in depth in terms of clinopyroxene geobarometry. The modeling result shows that olivine from the middle zone was a product of~28% crystallization of the parental magma. In addition, the PGE pattern of the rocks from this study indicates a lack of large-scale sulfide segregation due to the absence of crustal contamination. The composition of clinopyroxene is akin to those from island arc, but different from clinopyroxene from the rifting. Moreover, rocks from the middle zone have bulk-rock Th/Yb and Nb/Yb ratios similar to ratios of island arc basalts. Therefore, the Wangjiangshan intrusion could be formed in island arc environment. We argue that the tearing and breakoff of subduction oceanic slab resulted in asthenosphere upwelling during the Neoproterozoic long-term subduction beneath the northern margin of Yangtze. This provided a heat source for the partial melting of the metasomatized subcontinental lithospheric mantle and subsequent formation of mafic magma with island arc characteristics, which ascended in an extensional environment to form mafic-ultramafic layered intrusions in the Hannan arc.
THE FORMING AGE AND GEOCHEMISTRY CHARACTERISTICS OF THE GRANODIORITES IN HARIZHA, EAST KUNLUN AND ITS TECTONIC SIGNIFICANCE
GUO Xianzheng, JIA Qunzi, LI Jinchao, KONG Huilei, YAO Xuegang, LI Yazhi, MA Zhongyuan
2019, 25(2): 286-300. doi: 10.12090/j.issn.1006-6616.2019.25.02.027
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In order to probe the genesis and magmatic evolution sequence of the granites in the Harizha sliver polymetallic deposit, geochronological and geochemical studies of the Harizha granodiorite was carried out in this paper. The results show that the Harizha granodiorite has LA-ICP-MS zircon U-Pb age of 423.8±4.3 Ma, indicating that it was formed in late Silurian epoch. It has high contents of SiO2(71.21%~74.46%), Al2O3 (13.48%~14.46%), with K2O/Na2O ratios ranging from 1.32 to 1.54, and A/CNK values varying from 1.02 to 1.08, respectively. Thus, the Harizha granodiorite belongs to the high K calc-alkaline weak peraluminous granite. The granodiorite has right declined REE distribution patterns, with strong enrichment of LREE and relative depletion of HREE. It is enriched in Rb, Th, K, depleted in Ba and Nb, Ta, Ti, and has characteristics of the I to S transitional granite. It could be mainly sourced from the partial melting of upper crust gabbros, which is the product of regional post-collision extensional tectonic background.
Inside Cover
2019, 25(2): 301-301.
Abstract (90) PDF (11010KB)(10)
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Inside Cover
2019, 25(2): 302-302.
Abstract (92) PDF (3707KB)(9)
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