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    2024年第98卷第6期
    • 2024,98(6):0-0, DOI:

      Abstract:

    • ZHANG Qianqi,Edmund A. JARZEMBOWSKI,WANG Bo,ZHANG Haichun

      2024,98(6):1419-1428, DOI: 10.1111/1755-6724.15258

      Abstract:

      The Curvicubitidae is a Triassic cicada family with some taxa systematically debatable. Here a new curvicubitid species, Beaconiella tongchuanensis sp. nov., is established from the Middle Triassic Tongchuan Entomofauna in NW China. Restudy of the two Australian species of Beaconiella Evans, 1963 (B. fennahi and B. multivenata) confirms that they are different species and first reveals the hindwing venation of B. multivenata. A detailed restudy of Curvicubitus triassicus Hong, 1984 confirms the treatment of Curvicubitus as a junior synonym of Beaconiella. A key to all the six species of Beaconiella in Curvicubitidae is first given. Although reported from only three sites, the family Curvicubitidae potentially was globally distributed during the Middle–Late Triassic, implying that this family probably originated as early as the Early Triassic or even the Permian.

    • REN Xincheng,ZHANG Guanlong,WANG Jinduo,ZHANG Kuihua,ZHANG Xuecai,JI Ma,YU Hongzhou

      2024,98(6):1429-1440, DOI: 10.1111/1755-6724.15174

      Abstract:

      Permian sedimentary successions, widely distributed in the eastern Junggar Basin, may record key details on the closure of the Paleo-Asian Ocean in this region. Results of boreholes show that Permian strata is mainly composed of mudstone, sandy mudstone, siltstone, sandstone, sandy conglomerate, dolomite, and limestone. Detrital zircon U-Pb dating results of three sandstone samples yielded the calculated maximum ages of 296 Ma, 278 Ma and 293 Ma, indicating they possibly deposited during the Early Permian. Permian strata in the eastern Junggar Basin show similar rock associations and detrital zircon age data distribution patterns. Our new and compiled age data for sandstone samples in the eastern Junggar Basin and Bogda region yield predominant Paleozoic ages, close to their sedimentary ages. Such detrital zircon age data distribution patterns support the hypothesis that these Early Permian meta-clastic rocks in the eastern Junggar Basin and Bogda region were deposited in a subduction-related basin, and indicate an Early Permian Ocean prevented Precambrian detritus from the Central Tianshan block from depositing in the eastern Junggar Basin and Bogda region.

    • ZHAO Xiaochen,ZHAO Shaowei,LIU Chiyang,WANG Jianqiang,HUANG Lei,NIU Yazhuo,CHEN Yingtao,DU Fangpeng,PENG Heng,FENG Zeyi,DONG Yingchun

      2024,98(6):1441-1460, DOI: 10.1111/1755-6724.15165

      Abstract:

      The evolution and reforming history of the Cenozoic basins in the northeastern Tibetan Plateau (NETP) are significant for understanding the northeastward growth of the Tibetan Plateau. The sediments in these basins archived the spatial-temporal patterns of the surface uplift and deformation processes in response to remote effects of growth of the NETP. Here, we present an integrated provenance analysis of the Ningnan basin in the NETP to provide direct insights into the basin evolution and further constraints of the Tibetan Plateau’s northeastward growth. In this study, the Cenozoic strata (Sikouzi, Qingshuiying, Zhang’enpu and Ganhegou formations) in the Ningnan basin yield complex detrital zircon age distributions featured by predominant age populations at 200–360 Ma and 360–540 Ma with minor Precambrian ages. Detrital zircon U-Pb ages indicate that the southwestern Ordos Block, the western Qinling orogenic belt, and the eastern Qilian orogenic belt are primary source areas. Additionally, adjacent local paleo-uplifts (e.g., Xihua, Nanhua, Xiangshan, Liupan Mts.) also provided minor volumes of sediment. In addition, conglomerates and paleocurrent directions of the Sikouzi–Ganhegou formations exhibit an apparent change since the late Miocene, revealing an obvious provenance shift. The quantitatively determined mixing proportions of the surrounding source areas also reveals that the early source-to-sink system was replaced during the deposition of the Ganhegou Formation. Combined with previous studies, we suggest that the formation of the Ningnan basin was controlled by normal faults in extension setting and experienced continued sediment accumulation during the Qingshuiying–Zhang’enpu period; since the late Miocene, the significant provenance shift reflects the obvious northeastward growth of the NETP and led to the extinction of the Ningnan basin.

    • WANG Dazhao,LIU Yuhang,LENG Chengbiao,ZHEN Shimin,LIU Jiajun,ZHA Zhongjian

      2024,98(6):1461-1478, DOI: 10.1111/1755-6724.15183

      Abstract:

      Sparse felsic microgranitoid enclaves (FMEs) in the Shangshuiquan granite of the Zhangjiakou district, the north margin of the North China Craton, are fine-grained, dark-colored and exhibit subangular to subspherical shapes. They share similar mineral assemblages, chemical compositions, and zircon Hf isotope compositions to the host granite. New zircon U-Pb geochronology reveals that the FMEs crystallized at 156–153 Ma, while the Shangshuiquan granite formed at ca. 146 Ma. The FEMs are, therefore, 10 to 7 Ma older than the host granite. Combined with petrological evidence, we suggest that the FMEs are fragments of rapidly crystalized magmas, which were captured by the younger Shangshuiquan magma. Magmas of the FMEs and Shangshuiquan granite originated from the same reservoir. The Shangshuiquan granite is the result of small batches of magma being built up incrementally, and the FMEs belong to the earlier batches of magma. The lifespan of the Shangshuiquan magma reservoir exceeds 10 Ma. FMEs derived from cogenetic fragments have the potential to offer critical information about the formation process and timescale of granitic plutons.

    • ZHANG Hongbing,ZHOU Xuchen,LAI Shaocong,ZHANG Hua,QIN Jiangfeng

      2024,98(6):1479-1488, DOI: 10.1111/1755-6724.15194

      Abstract:

      Mafic enclaves in granites are generally considered to represent coeval mafic melts that derived from metasomatized mantle, which can provide valuable information about crust–mantle interaction. Exploring the genetic links between the mafic enclaves and their host monzogranite from the Triassic Zhashui Pluton, Qinling orogenic belt. The enclaves (220 ± 4.6 Ma) and the monzogranite (220 ± 2.8 Ma) display identical zircon U-Pb ages, and they also share similar trace element and zircon Lu-Hf isotopes, indicating a cognate source. The monzogranite displays zircon εHf(t) values of ?0.99 to +1.98, while the mafic enclaves show similar values of ?0.45 to +3.26; however, differences in mineral chemistry reveal different crystallization conditions. The amphibole from the mafic enclaves has higher temperature and pressure (757℃; 2.65 kbar) compared to those of the host monzogranite (733℃; 1.96 kbar), suggesting that mafic minerals in the enclaves crystallized at an early stage. Moreover, apatite in the mafic enclaves displays slightly higher volatile contents (0.72 wt%) than those of the monzogranite (0.66 wt%), indicating a volatile-rich condition. These results suggest that the mafic enclaves represent early hydrous mafic cumulates in the granitic chamber, and subsequent magma convection would have led to the formation of the mafic enclaves.

    • LIU Jiawang,WANG Shuzhi,WANG Tao,CAO Chong,QIU Junting,XIE Fenquan

      2024,98(6):1489-1500, DOI: 10.1111/1755-6724.15201

      Abstract:

      The Zaozigou gold deposit lies south of the Xiahe–Hezuo regional fault zone in the western Qinling orogenic belt and contains many intermediate to felsic dikes. Diorite porphyry, quartz diorite porphyry and biotite diorite porphyry are mineral-bearing dikes, whereas granite porphyry is unrelated to gold mineralization. To compare the relationship between different dikes and mineralization, this study analyzed the cathodoluminescence (CL) of zircon crystals in all four types of dikes exposed in the Zaozigou deposit, using a zircon typological classification. The formation temperature of the granite porphyry (734°C) was higher than the average temperature of the other three types of dikes (704°C), whereas the former’s alkalinity index (395) was lower than the average alkalinity index of the other three dikes (425). The ΣREE amount of granite porphyry (147.18 ppm) was smaller than the average ΣREE amount of the other three dikes (246.80 ppm) and its δEu value (0.33) was larger than the average δEu values of the other three dikes (0.30). The U-Pb ages of zircon in the four types of dikes were relatively consistent with the crystallization ages of approximately 240 Ma, which indicates that all four types of dikes intruded in the Middle Triassic. Compared to the other three ore-bearing dikes, the morphology of the zircon crystals in the barren dikes evolved from S13 to S5 and then returned to S13. These results indicate that the barren dike underwent an increase in temperature and a decrease in alkalinity, which may be an important reason for the absence of mineralization.

    • GUO Zixiao,HU Yazhen,DU Qingying,LIU Yadong,QIN Guohong,PENG Xiaotong

      2024,98(6):1501-1510, DOI: 10.1111/1755-6724.15187

      Abstract:

      Iddingsitization is an aqueous alteration that is known to take place in meteorites and continental basalts providing a potential habitat for microbial life. However, little is known about the exact mode by which this reaction occurs in the hadal seafloor and its implication for the deep subsurface biosphere. A comprehensive investigation of hadal basalts from the southern Mariana Trench (SMT) conducted with microscopic examinations shows that iddingsite occurs as augite-hosted veins, rims, and mineral grains formed completely in place of augite within the SMT basalts. Carbon geochemistry indicates that organic matter with homogenous δ13C values between ?27.8‰ and ?27.2‰ might be biogenically accumulated in the SMT basalts. Furthermore, the close spatial relationships between carbonaceous matter (CM) and goethite in iddingsite point to microbial attachment to iddingsite minerals. Thus, iddingsitization might have fueled H2-utilizing microorganisms inhabiting the hadal oceanic crust, thereby leading to the formation of CM, as implied by oxygen isotopic compositions revealing low alteration temperatures (32–83oC) favorable for microbial growth. In all, microbial biosignatures associated with iddingsite in the SMT basalts are highlighted, and these results could pave the way for deciphering the deep subsurface biosphere at hadal zones.

    • HAN Zaihua,LIU Hua,LI Jun,CHENG Bin,ZHANG Hongrui,MENG Xiangyu

      2024,98(6):1511-1532, DOI: 10.1111/1755-6724.15256

      Abstract:

      Overpressure is widely developed in deep petroliferous strata in the hinterland of the Junggar Basin. However, a comprehensive understanding of its origin and effect on hydrocarbon distribution and enrichment remains lacking. In this study, we employ five empirical methods and comprehensive geological analysis to identify the origin of overpressure, and uncover the effect of overpressure on hydrocarbon enrichment. The results indicate that disequilibrium compaction is not a significant factor in overpressure generation. Instead, hydrocarbon generation, pressure transfer and diagenesis are the primary causes. The empirical methods support this conclusion. There is a positive correlation between overpressure intensity and source rock thickness and maturity. Notably, widespread cross-formational migration of hydrocarbon bearing fluid occurred, with sandstone overpressure exceeding that of adjacent shale in non-source strata. Furthermore, there is a distinct transformation from smectite to illite near the top of overpressure. Hydrocarbon generation pressurization and pressure transfer significantly effect hydrocarbon enrichment. The overpressure caused by hydrocarbon generation drives hydrocarbon migration and accumulation, establishing an optimal energy configuration between reservoir and cap rock. Faults play a crucial role in hydrocarbon vertical migration and pressure relief. The overpressure in reservoirs can reduce the porosity and permeability thresholds and enhance the charging capacity of oil and gas.

    • LI Zhiyuan,HUANG Zhilong,WANG Junhui,WANG Boran,YAO Wenjiao,JIA Xueli,YANG Yizhuo,PAN Yongshuai,WU Yunfei

      2024,98(6):1533-1556, DOI: 10.1111/1755-6724.15257

      Abstract:

      Hyperpycnal deposits has gradually emerged as a current research hotspot, with a special focus on lacustrine hyperpycnal deposits. However, our understanding of the formation mechanism and distribution of high-quality reservoirs in hyperpycnal deposits remains insufficient. In this study, the formation mechanism and distribution of high-quality reservoirs in the second member of the Sangonghe Formation are studied through sedimentology, petrology, and geochemistry, and 10 types of lithofacies were identified in the depositional sequences of the hyperpycnal flow. These can be summarized as gravelly bed to suspended load lithofacies association (GBS), gravelly reverse to normal compound-graded (GNR), coarse-grained sandy suspended load (CSS), and fine-grained sandy suspended load (FSS) lithofacies associations. The hyperpycnal system can be divided into four individual units: restricted channel, unrestricted channel, lobe, and levee. The reservoir quality varies with lithofacies. Gravelly bed load lithofacies has coarse grain sizes, high content of rigid minerals, and soluble components, such as magmatic rock fragments. Therefore, the gravelly bed load lithofacies reservoir has developed dissolution pores and well-preserved pore throats. Its reservoir quality is good. GBS and GNR are the main lithofacies associations in the restricted channel, where type I and type II reservoirs developed. The unrestricted channel is dominated by the CSS lithofacies association, with type III reservoirs developed. The lobe is dominated by the CSS and FSS lithofacies associations, with type III and type IV reservoirs developed. High-quality reservoirs mainly develop in the restricted and unrestricted channels, whereas reservoirs in the lobe have poor quality. The levees are dominated by siltstone and gray mudstone and are generally nonreservoirs.

    • XU Xiaotong,ZENG Lianbo,DONG Shaoqun,DIWU Pengxiang,LI Haiming,LIU Jianzhong,HAN Gaosong,XU Hui,JI Chunqiu

      2024,98(6):1557-1573, DOI: 10.1111/1755-6724.15259

      Abstract:

      Fracture effectiveness plays a key role in gas productivity of ultra-deep tight sandstone reservoirs, Kuqa depression, Tarim Basin. Based on cores, thin sections, well logging, well testing and production data, the study evaluated fracture effectiveness and illustrated its impacts on gas productivity. High-angle and vertical shear fractures are the most important types. Distribution of effective fractures shows great heterogeneous. Fracture effectiveness is influenced by tectonism, diagenesis and in-situ stress. Earlier fractures or fractures in close to gypsum rock are easier to be filled. Completely filled fractures can be reopened under late tectonism. Dissolution improves local fracture effectiveness. Minerals spanning fracture surfaces protect fracture effectiveness from late compression. Fractures filled with calcite can be activated by acidification. Effective fractures parallel to maximum horizontal principal compressive stress direction show larger aperture. Overpressure can decrease the effective normal stress to maintain fracture effectiveness. With exploitation, decline in pore pressure reduces fracture effectiveness. Linear density, aperture, and strike of effective fractures influence gas productivity. Effective fractures greatly enhance matrix permeability. Therefore, more abundant and larger aperture fractures are always corresponded to higher productivity. However, effective fractures also facilitate late water invasion, especially, both mutually parallel. Intense water invasion leads to rapidly declines in productivity.

    • DAI Guobiao,TANG Yuegang,LIU Ao,WANG Xiaoshuai,LI Ruiqing

      2024,98(6):1574-1585, DOI: 10.1111/1755-6724.15155

      Abstract:

      In this study, the abundance of trace elements in the Baiyinhua depression coal and its relationship with the coal depositional environment was examined. (1) The content of arsenic in the Baiyinhua depression coal is that of a typically high arsenic coal from the late Mesozoic of China. The average arsenic content of Baiyinhua coal is 24.93 times, the highest being 132.71 times, that of Chinese coal. Coal rank is not a controlling factor affecting arsenic enrichment in coal. (2) Arsenic is primarily enriched in the syngenetic and diagenetic stages, the enrichment being most obvious in the syngenetic stage, with the intrusion of a magmatic-hydrothermal solution in the epigenetic stage also providing rich sources of arsenic. (3) The Baiyinhua coal-forming plant material is mainly woody plants. The coal seam was covered with deep water, the oxygen supply was very weak, the bacteria very few, the sedimentary environment of the swamp relatively calm and the degree of damage to the woody plants is very low. The minerals in the coal are mainly quartz and clay minerals. The coal ash yield of Baiyinhua is small, with SiO2, Al2O3, MgO, K2O, TiO2, MnO and P2O5 mainly being combined in the inorganic minerals of the coal.

    • LOU Pengcheng,MIAO Zhongying,ZHENG Mianping,LIU Yuanying,FANG Linhao

      2024,98(6):1586-1601, DOI: 10.1111/1755-6724.15218

      Abstract:

      Western Yunnan is an important area for Mesozoic marine strata, development of which helps to reconstruct paleoenvironments in the eastern Tethys. To bring knowledge of eastern Tethys up to that of western Tethys, this study focuses on its sedimentary characteristics and paleoenvironmental significance concentrating on the Xiushan section of the Simao Basin with analyses of the petrology, element geochemistry, and C-O-Sr isotopes. Samples are micrite, bioclastic limestone, marl, and mixed calcareous clastic rocks with the 87Sr/86Sr values of limestone ranging from 0.708255 to 0.708933; the δ13C values of the limestone range from ?5‰ to +1.5‰ and the δ18O values range from ?13.7‰ to ?9.1‰. Based on the results, it is concluded that the Middle Jurassic limestones in the Simao Basin were deposited in a tidal flat environment with a strong influence of terrigenous input. At least one transgression event occurred during the depositional period. The paleoclimate as a whole changed from dry hot to humid hot and back to dry hot again. These enriched and improved results provide further data support for a comparison of the paleoenvironments between the eastern and western Tethys.

    • LI Yaohua,WANG Yang,BI Caiqin,WANG Qianyou,SHI Yu,XU Yinbo,YUAN Yuan,TONG Lihua,TANG Yue,SHAN Yansheng,LIU Weibin

      2024,98(6):1602-1614, DOI: 10.1111/1755-6724.15188

      Abstract:

      The utilization of CO2-Enhanced Coal Bed Methane (CO2-ECBM) technology is pivotal in realizing the environmentally responsible and efficient exploitation of Coalbed Methane (CBM) energy resources. The optimization of carbon capture, utilization, and storage (CCUS) for carbon reduction mandates a nuanced understanding of the diverse geological attributes present in CBM reserves globally. Traditional estimations of CO2-ECBM's carbon sequestration potential have predominantly relied on rudimentary empirical models, notably those proposed by the United States Department of Energy (DOE), which overlook the intrinsic geological conditions and the physicochemical properties of subsurface fluids. Addressing these limitations, our study implements the advanced DR/Henry mixed adsorption model in tandem with the Peng-Robinson equation of state (PR-EOS). This approach meticulously identifies the critical parameters governing the mass exchange ratios between CO2 and CH4, pertinent to in-situ geological environments. Subsequently, we have formulated a comprehensive carbon sequestration potential assessment framework. This innovative model adheres to the mass conservation principles for individual CO2 and CH4 components, taking into account the specific surface and stratigraphic conditions prevalent. Employing this refined methodology, we evaluated the CO2-ECBM carbon sequestration potential of the 40 evaluation units of extensional, compressive, and cratonic continental coal bearing basins in China's three major temperature-pressure systems across different depth domains and coal ranks within 2000 m. Our findings reveal that the theoretical carbon sequestration capacity of China's continental coal-bearing basins is approximately 59.893 billion tons. Concurrently, the potential ECBM output stands at an estimated 4.92 trillion cubic meters, underscoring the substantial environmental and energy benefits inherent in harnessing CO2-ECBM technology effectively. The regional analysis revealed that North and Northwest China hold the highest sequestration and recovery potential, followed by the Northeast and Southern regions, respectively. Specific areas, including the eastern edge of the Ordos Basin and southern Junggar Basin, Qinshui, Huoxi, Xishan, and other areas in Shanxi, present promising future prospects for geological carbon storage in unrecoverable coal seams.

    • WU Zhanhui,WANG Xinyi,LI Jiexiang,CUI Junchao,ZHANG Bo

      2024,98(6):1615-1636, DOI: 10.1111/1755-6724.15255

      Abstract:

      The karst groundwater of Cambrian limestone may become an important water source for industry and agriculture in the Pingdingshan area, and is also a potential threat to mining safety. Therefore, to find out the origin, flow paths, and hydrogeochemical processes of karst groundwater beneath the Pingdingshan coalfield, a total of 16 water samples were collected. Our findings confirmed that the karst groundwater is mainly recharged by precipitation. The precipitation can directly supply the deep aquifer of the karst water system through the southwest limestone outcrops, and this area mostly includes the southern part of mines No. 11, No. 9, and the hidden outcrops in the southern part of mine No. 2. What is more, the areas adjacent to the synclinal axis, including mines No. 10, No. 12, and No. 8, may be the main discharge areas. A mixing model of 87Sr/86Sr and Sr showed that in the southwest Pingdingshan coalfield, the proportion of precipitation decreased gradually from the recharge area to the discharge area, ranging from 89.1% to 17.1%. Besides, the northeast Pingdingshan coalfield is another recharge area for the whole karst system, thus, the infiltrating groundwater will indirectly supply the deep aquifer through Quaternary deposition near the mine No. 13. Our research results can provide theoretical support for the prevention and control of groundwater disasters and the development and utilization of regional groundwater resources in the coalfield in Northern China.

    • GUO Junhan,LIU Kai,MA Yan

      2024,98(6):1637-1648, DOI: 10.1111/1755-6724.15147

      Abstract:

      Underground space resources are important for the purposes of urban sustainable development and are a significant means by which to realize three-dimensional urban development. A reasonable and scientific evaluation of underground space resources is the foundation for the rational use of land resources and urban planning. On the basis of the geological conditions used by preceding researchers, this study adds the analysis of two influencing factors of social and economic value, alongside existing facilities and protection needs. The evaluation index is quantified and the comprehensive quality evaluation system of underground space resources is constructed. Finally, taking the Nanshan District of Shenzhen as an example, the evaluation of underground space resources is carried out. The results show that for shallow underground space, the comprehensive quality of underground space resources development in Nanshan District is generally high. Nantou, Nanshan and Yuehai streets are recommended as areas to actively develop underground space, whereas the Qianhai and Houhai areas are recommended to be used with caution in the development and construction of their underground space. In addition, this study also provides a reference for the purposes of underground space planning in the Nanshan district of Shenzhen.

    • LAO Haigang,XU Hongyuan,WANG Yongshi,MAO Cui,Osman Salad HERSI,LI Dianheng

      2024,98(6):1649-1658, DOI: 10.1111/1755-6724.15176

      Abstract:

      Horsetailing is an important feature to identify the strike-slip structure and indicates the movement mode of the fault. However, the formation mechanism of horsetailing in the extensional regime remains unclear. In this study, the formation process of horsetailing is reproduced through physical experiment, simulating the Linnan sag in the extensional regime. The results of the physical experiment demonstrates that the formation of the horsetailing in the extensional regime requires two phases of non-coaxial stretching plus the segment of the principal fault. The stretching distance in the early phase is slightly smaller than that in the middle–late phase. The segment point of the principal fault is only the intersection of the horsetailing structure and the principal fault. The horsetailing formed in the extensional regime is different from that in the strike-slip regime. For the formation of structure, the principal fault is dip-slip in the early phase and then becomes an oblique-slip in the middle–late phase, and the horsetailing is composed of the middle–late new tensile faults. The fault properties of the horsetailing in the extensional regime has important guiding significance for the longitudinal fluid migration along the fault in petroliferous basins.

    • LI Guang,LIU Shuaiqi,MA Fengshan,GUO Jie,HUI Xin

      2024,98(6):1659-1671, DOI: .1111/1755-6724.15217

      Abstract:

      Water inrush is a common disaster in submarine mining. The key to preventing this disaster is to restrict the water-conducting fissure propagation induced by mining from forming a flow channel to communicate with the overlying aquifer. The mechanical behavior of hydraulic fractures under stress disturbance lies at the heart of the problem. Hence, the multiple parallel bond—grain-based model (multi Pb-GBM) is introduced to explore the hydraulic fracture evolution law of crystalline granite under the influence of stress disturbance. The results show that: hydraulic fracturing under stress disturbance is clearly affected by the stress wave frequency; the higher the frequency is, the more difficult it is to crack, but the crack propagation speed is faster after crack initiation; the propagation direction of a crack is deflected towards the propagation direction of the stress wave and the crack dip angle is controlled by the maximum principal stress; the internal crystal boundary of the same mineral is the most stable one among the three contacts, the contact boundary between different minerals being the most fragile one. This research not only has a practical application value to seabed mining engineering, but also has important theoretical significance in enriching deep rock mechanics theory.

    • LUO Fanglu,XIAO Zhiyong,XU Rui,CHANG Yiren,MA Yizhen,CAO Wei,WU Yunhua,WANG Yichen

      2024,98(6):1672-1681, DOI: 10.1111/1755-6724.15189

      Abstract:

      Depleted shergottites record unique information about the primary composition and differentiation of the mantle of Mars. Their petrology, geochemistry, and cosmic ray exposure and crystallization ages suggest that most of them were excavated by a single young impact in the Amazonian-aged lava flows of the Tharsis and Elysium volcanic provinces. However, the difficulties of deriving consistent model ages for individual craters and inadequate evaluation of 3–7 km craters capable of ejecting martian meteorites have not been settled. Here we perform detailed geological investigations and crater statistics in patches of impact melt deposits for potential source craters of depleted shergottites with D > 3 km, especially those in the Tharsis and Elysium volcanic provinces. By excluding the effect of heterogeneous textures across ejecta deposits, which hinder straightforward extraction of superposed production populations, our systematically updated model ages reveal that Chakpar crater at the northern flank of Ascraeus Mons is the best-fit candidate. The local context of this crater permits establishing a link between the meteorites and specific lava flows. The long-lived volcanic center here may experience an eruption and/or local deposition hiatus for about 1.8 billion years, and abundant subsurface water existed when the impact occurred at about 1.1 million years.

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    2024年第98卷第6期
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    • 青藏高原东北缘祁连–海原断裂带中段金强河断裂晚第四纪滑动行为

      梁淑敏, 郑文俊, 陈干, 张培震, 张冬丽, 毕海芸, 杨雪, 张逸鹏, 段磊, 卢本添

      Abstract:

      祁连–海原断裂带控制着青藏高原东北缘地区的强震活动。在其中段的金强河断裂是天祝地震空区一条关键的活动断裂,但目前对该断裂的滑动行为认识不足。本文针对沿金强河断裂的水平位移分布,利用WorldView-2立体像对和无人机摄影测量数据,提取断裂沿线高精度的DEM数据,并进行精细的构造地貌解译和水平位错测量。通过断错地貌标志的测量,得到135个位错量和8个位错丛集。同时,利用放射性碳测年方法构建4个典型点断错河流阶地的地貌单元年龄序列,从而通过位错与年龄的关系将位错丛集和地貌单元年龄序列关联起来,并获得金强河断裂全新世的滑动速率在 ~4–12 ka期间为4.8–5.6 mm/a ,在 ~4 ka以来为2.9–4.7 mm/a。最近的三次地震事件的复发间隔约为1000年,形成了一个地震活跃期,揭示着近1500年来缺乏破裂记录的金强河断裂可能具有较高的地震危险性。

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    • 南阿尔金早古生代构造演化:来自茫崖花岗质岩石地球化学、锆石U-Pb和Lu-Hf同位素的证据

      徐楠, 吴才来, 刘和武, 宋帅兵, 张贵生, 郑坤, 高栋

      Abstract:

      南阿尔金造山带是中国西南典型的俯冲造山带,由南阿尔金蛇绿混杂岩带和南阿尔金陆块组成,位于柴达木板块北侧。造山带出露大量早古生代花岗质岩石,但是这些岩石的成因及构造环境尚未查明。本文对茫崖花岗质岩石进行岩石学和地球化学研究,确定岩浆活动的期次,并深入了解南阿尔金造山带的构造演化过程。茫崖花岗质岩浆活动可以划分为三期:494-458Ma,450-436Ma和416-404Ma。根据这些岩石的成岩构造环境,我们认为第一期岩浆活动与南阿尔金洋的北向俯冲有关,形成了大量高价钙碱性、I型花岗质岩石。南阿尔金洋闭合后,柴达木板块开始向南阿尔金陆块碰撞,行了了一系列高价钙碱性、I型花岗岩。第三期岩浆活动形成了大量的造山后A-型花岗岩。

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    • 超微量(80nanomole)硫化物硫酸盐硫同位素的EA-IRMS测试

      武晓珮, 范昌福, 胡斌, 高建飞, 李延河

      Abstract:

      常规EA-IRMS进行硫同位素测试时需硫量大于2 μmol,这限制了该技术在测试含硫量低的样品时的使用。如此大的需硫量是因为He载气携带样品气体在经过元素分析仪(EA)时的流速为~100 mL/min,而气体同位素质谱仪仅允许气体以低流速进入,所以99.7%的混合气体会通过连续流接口排出,以保证混合气体以~0.3 mL/min的流速通过连续流接口。因此,大部分的样品气体会被浪费,样品的利用率仅有0.3%。在本研究中,我们将自主研发的冷冻富集、分离与纯化系统与EA-IRMS联用测试了六种标准物质的硫同位素,并检测该系统的表现。实验结果表明,使用本研究中改进的方法进行硫化物和硫酸盐标准物质的硫同位素测试,得到的硫同位素结果与常规方法一致,即需硫量仅80 nmol即可得到硫同位素测试结果精度 ±0.24‰–±0.76‰ (1σ),与使用吸附柱进行硫同位素测试的方法获得的精度相似。所以,改进后的EA-IRMS可以实现超微量硫化物、硫酸盐的硫同位素测试。此外,本方法也可应用至需样量低至100 nmol的碳、氮和氧同位素分析测试工作中。

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    • 粤北早古生代强过铝质花岗岩及其共生岩石的岩石成因及对广西运动的指示意义:来自元素和Sr-Nd-Hf同位素的制约

      贾小辉, 王晓地, 邱啸飞

      Abstract:

      本文系统报道了粤北地区早古生代强过铝质花岗岩及其共生岩石的锆石U-Pb年代学、主、微量元素及Sr-Nd-Hf同位素组成,探讨其源区特征、岩石成因及构造意义。青州花岗闪长岩为弱-强过铝质,A/CNK= 1.05–1.96。它们具有相对高的初始Sr同位素组成ISr= 0.7087– 0.7148和低的εNd(t)值(-11.2 – -10.1),以及变化的εHf(t)值-13.4– +4.81。与之不同,大帽山花岗闪长岩为准铝质(A/CNK= 0.79– 0.94),ISr= 0.7083– 0.7110, εNd(t)= -7.92– -5.28和εHf(t)= -8.69– -2.06。高寿石英闪长岩为准铝-强过铝质(0.87– 1.24),ISr值和εNd(t)值分别为0.7104– 0.7111和-9.64– -8.63。元素和Sr-Nd-Hf同位素组成结果显示,青州、大帽山和高寿花岗质侵入岩主要分别源自变杂砂岩、英安质岩和角闪石岩的部分熔融。结合前人的研究成果,这些强过铝质花岗岩形成于同造山环境。本文尝试提出一种关于华南早古生代花岗岩的岩石成因及区域地壳重组的新思路。而广西运动动力机制的揭示需要更加广阔的视野和更加丰富的地质证据。

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    2024年第98卷第6期
    • Birendra P. Singh, Kapesa Lokho, Naval Kishore, Nancy Virmani

      2014,88(2):380-393, DOI:

      Abstract:

      A new locality bearing ichnofossils of the Cruziana Assemblage Zone-III from the Mussoorie syncline, Lesser Himalaya, is located in rocks of Member-B of the Dhaulagiri Formation, Tal Group, exposed along the Maldewta-Chhimoli fresh road cut section. The site yielded ichnofossils Bergaueria perata, Cochlichnus anguineus, ?Diplocraterion isp., Dimorphichnus obliquus, diplichnitiform Cruziana bonariensis, Diplichnites gouldi, Glockeria isp., Helminthopsis isp., Monomorphichnus lineatus, Phycodes palmatum, Palaeophycus striatus, Planolites beverleyensis, Planolites montanus, Treptichnus cf. T. pedum, scratch marks and an undetermined worm impression. An Early Cambrian age (Cambrian Series 2) is assigned to the ichnofossil-bearing strata based on the stratigraphic position between the Drepanuroides and Palaeoolenus trilobite zones. A revised Cambrian ichnofossil zonation is presented for the Tal Group of the Mussoorie syncline. Together with their occurrence on rippled surfaces, and the lateral displacement of some trackways (due to current action), a sub-aqueous shallow-marine depositional setting is proposed for the rocks of Member-B.

    • ZHU Song, WU Zhenhan, ZHAO Xitao, LI Jianping, WANG Hua

      2012,86(1):266-283, DOI:

      Abstract:

      Many moraines formed between Daduka and Chibai in the Tsangpo River valley since Middle Pleistocene. A prominent set of lacustrine and alluvial terraces on the valley margin along both the Tsangpo and Nyang Rivers formed during Quaternary glacial epoch demonstrate lakes were created by damming of the river. Research was conducted on the geological environment, contained sediments, spatial distribution, timing, and formation and destruction of these paleolakes. The lacustrine sediments 14C (10537±268 aBP at Linzhi Brick and Tile Factory, 22510±580 aBP and 13925±204 aBP at Bengga, 21096±1466 aBP at Yusong) and a series of ESR (electron spin resonance) ages at Linzhi town and previous data by other experts, paleolakes persisted for 691~505 kaBP middle Pleistocene ice age, 75–40 kaBP the early stage of last glacier, 27–8 kaBP Last Glacier Maximum (LGM), existence time of lakes gradually shorten represents glacial scale and dam moraine supply potential gradually cut down, paleolakes and dam scale also gradually diminished. This article calculated the average lacustrine sedimentary rate of Gega paleolake in LGM was 12.5 mm/a, demonstrates Mount Namjagbarwa uplifted strongly at the same time, the sedimentary rate of Gega paleolake is more larger than that of enclosed lakes of plateau inland shows the climatic variation of Mount Namjagbarwa is more larger and plateau margin uplifted more quicker than plateau inland. This article analyzed formation and decay cause about the Zelunglung glacier on the west flank of Mount Namjagbarwa got into the Tsangpo River valley and blocked it for tectonic and climatic factors. There is a site of blocking the valley from Gega to Chibai. This article according to moraines and lacustrine sediments yielded paleolakes scale: the lowest lake base altitude 2850 m, the highest lake surface altitude 3585 m, 3240 m and 3180 m, area 2885 km2, 820 km2 and 810 km2, lake maximum depth of 735 m, 390 m and 330 m. We disclose the reason that previous experts discovered there were different age moraines dividing line of altitude 3180 m at the entrance of the Tsangpo Grand Canyon is dammed lake erosive decay under altitude 3180 m moraines in the last glacier era covering moraines in the early ice age of late Pleistocene, top 3180 m in the last glacier moraine remained because ancient dammed lakes didn’t erode it under 3180 m moraines in the early ice age of late Pleistocene exposed. The reason of the top elevation 3585 m moraines in the middle Pleistocene ice age likes that of altitude 3180 m. There were three times dammed lakes by glacier blocking the Tsangpo River during Quaternary glacial period. During other glacial and interglacial period the Zelunglung glacier often extended the valley but moraine supplemental speed of the dam was smaller than that of fluvial erosion and moraine movement, dam quickly disappeared and didn’t form stable lake.

    • WANG Runfu, XU Shichao, WU Xiaochun, LI Chun, WANG Suozhu

      2013,87(5):1185-1197, DOI:

      Abstract:

      Shansisuchus shansisuchus Young, 1964 was restudied on the basis of a new specimen. Some anatomical features that were either briefly or not described at all in the original study were detailed. The new specimen not only provides further information on the skull anatomy and the vertebral column but also expands the range of the geographical distribution of the taxon. With new information, the diagnosis of S. shansisuchus was emended and its phylogenetic relationships were further analyzed. S. shansisuchus differs from other archosauriforms primarily in the presence of a large subnarial fenestra anterior to the antorbital fenestra, tongue-in-groove articulations between the ascending process of the premaxilla and nasal and between the premaxilla and maxilla, a tall and posterodorsally directed ascending process of the maxilla, a knee-shaped process of the postorbital projecting into the orbit, a broad descending process of squamosal distally well forked and a large, deeply bow-shaped intercentrum tightly anchoring/capping the sharp ventral edges of two neighboring centra together in cervical and at least first eight dorsal vertebrae. With additional information derived from the new specimen, the phylogenetic relationships of S. shansisuchus were reanalyzed; it is closely related to Erythrosuchus-Vjushkovia clade.

    • CHEN Lan1, 2, 3, * , YI Haisheng4, 5, TSAI Louis Loung-Yie2, XU Guiwen1, DA Xuejuan1, LIN Andrew Tien-Shun3

      2013,87(2):540-554, DOI:

      Abstract:

      The Biluo Co and Amdo 114 station, northern Tibet, cropping out the Early Toarcian and Middle-Late Tithonian (Jurassic) organic-rich black shales, have been a focus to petroleum geologists in discussing their oil-producing potential. This paper first reports the trace elements and rare earth elements to discuss the paleoenvironments, redox conditions and sedimentary mechanisms of those black shales. Both sections exhibit variation in trace element abundances with concentrations <0.1 ppm to 760 ppm, mostly enriched in V, Cr, Ni, Cu, Zn, Mo, Ba and U. Element ratios of Ni/Co, V/Cr, U/Th and V/(V+Ni) plus U were used to identify redox conditions. The shale-normalized rare earth element (REE) patterns are characterized by the flat-shale type with instable Ce anomalies and very weekly positive Eu anomalies. Positive Ceanom values are significant with values varying between –0.064 and 0.029 in Biluo Co, which may be interpreted as release of REE and input of riverine terrestrial matter with rich Ce (resulting in pH change) during the anoxic conditions. In the middle parts of Amdo 114 station, distinct negative Ceanom values are observed (?0.238 to ?0.111) and associated surface water warming were interpreted as being related to a major sea level rise. In contrast, the formation of the black shales in the lower and upper part of the studied succession took place during a cooler (Ceanom values >–0.10), lower surface water productivity, and lower sea-level stage. Thus, we emphasize the role of different factors that control the formation of local and regional black shales. The most important factors are sea-level fluctuations and increasing productivity.

    • CHEN Jitao, LEE Jeong-Hyun

      2014,88(1):260-275, DOI:

      Abstract:

      This paper reviews the current progress and problems in the study of microbialites and microbial carbonates. Microbialites and microbial carbonates, formed during growth of microbes by their calcification and binding of detrital sediment, have recently become one of the most popular geological topics. They occur throughout the entire geological history, and bear important theoretical and economic significances due to their complex structures and formative processes. Microbialites are in place benthic microbial buildups, whereas microbial carbonates can be classified into two categories: stabilized microbial carbonates (i.e., carbonate microbialites, such as stromatolites and thrombolites) and mobilized microbial carbonates (i.e., microbial carbonate grains, such as oncoids and microbial lumps). Various texture, structures, and morphologies of microbialites and microbial carbonates hamper the systematic description and classification. Moreover, complex calcification pathways and diagenetic modifications further obscure the origin of some microbialites and microbial carbonates. Recent findings of abundant sponge spicules in previously identified “microbialites” challenge the traditional views about the origins of these “microbialites” and their implications to reef evolution. Microbialites and microbial carbonates did not always flourish in the aftermath of extinction events, which, together with other evidences, suggests that they are affected not only by metazoans but also by other geological factors. Their growth, development, and demise are also closely related to sea-level changes, due to their dependence on water depth, clarity, nutrient, and sunlight. Detailed studies on microbialites and microbial carbonates throughout geological history would certainly help understand causes and effects of major geological events as well as the co-evolution of life and environment.

    • SHEN Caizhi, Lü Junchang, LIU Sizhao, Martin KUNDRáT, Stephen L. BRUSATTE, GAO Hailong

      2017,91(3):763-780, DOI:

      Abstract:

      A new troodontid dinosaur, Daliansaurus liaoningensis gen. et sp. nov., is erected based on a nearly complete specimen from the Lower Cretaceous Yixian Formation of Beipiao City, Liaoning Province, China. This well preserved skeleton provides important new details of the anatomy for Liaoning troodontids, and gives new insight into their phylogenetic relationships and evolution. Daliansaurus is distinguished from other troodontids by an enlarged ungual on pedal digit IV, which is approximately the same size as the sickle-shaped second ungual, and is differentiated from other Liaoning troodontids by a number of characters of the skull, manus, pelvis, and hindlimb. A phylogenetic analysis recovers Daliansaurus within a subclade of Liaoning troodontids that also includes Sinovenator, Sinusonasus, and Mei. We erect a name for this group—Sinovenatorinae—and argue that it reflects a localized radiation of small-bodied troodontids in the Early Cretaceous of eastern Asia, similar to previously recognized radiations of Liaoning dromaeosaurids and avialans. As more Liaoning theropods are discovered, it is becoming apparent that small, feathered paravians were particularly diverse during the Early Cretaceous, and future work is needed to clarify how this diversity arose, which species coexisted, and how these numerous species partitioned niches.

    • Richard H. SILLITOE

      2014,88(z2):597-598, DOI:

      Abstract:

      Please refer to the attachment(s) for more details

    • DU Chunguo, WANG Jianjun, ZHANG Jun, WANG Ping, XUE Mei, ZHOU Huayao

      2014,88(3):865-877, DOI:

      Abstract:

      On the basis of field observations, microscopic thin-sections and laboratory data analysis of ten faults in Xuanhan County area, northeastern Sichuan Basin, central China, the internal and megascopic structures and tectonite development characteristics are mainly controlled by the geomechanical quality in brittle formation of the Changxing-Feixianguan Formation. The fluid transportation performance difference between the faults formed by different geomechanics or different structural parts of the same fault are controlled by the megascopic structure and tectonite development characteristics. For instance, the extension fault structure consists of a tectonite breccia zone and an extension fracture zone. Good fluid transportation performance zones are the extension fracture zone adjacent to the tectonite breccia zone and the breccia zone formed at the early evolutionary stage. The typical compression fault structure consists of a boulder-clay zone or zones of grinding gravel rock, compression foliation, tectonite lens, and dense fracture development. The dense fracture development zone is the best fluid transporting area at a certain scale of the compression fault, and then the lens, grinding gravel rock zone and compression foliation zones are the worst areas for hydrocarbon migration. The typical tensor-shear fault with a certain scale can be divided into boulder-clay or grinding gravel rock zones of the fault, as well as a pinnate fractures zone and a derivative fractures zone. The grinding gravel rock zone is the worst one for fluid transportation. Because of the fracture mesh connectivity and better penetration ability, the pinnate fractures zone provides the dominant pathway for hydrocarbon vertical migration along the tensor-shear fault.

    • MA Shengming, ZHU Lixin, LIU Chongmin, XI Mingjie, TANG Shixin

      2013,87(3):843-857, DOI:

      Abstract:

      This paper discusses the enrichment and depletion regularities for porphyry copper-molybdenum ore deposits in different regions and varied deposit genetic types in the same area, taking three porphyry copper-molybdenum ore deposits (i.e., the Chengmenshan in Jiangxi, Wunugetushan in Inner Mongolia, Baishantang in Gansu) and two copper deposits in Gansu Province (the Huitongshan skarn deposit and Gongpoquan composite deposit) as case studies. The results show that porphyry Cu-Mo deposits or skarn copper deposits include both enrichment of the ore-forming elements and associated elements, and depletion of some lithophile dispersed elements, rare earth elements (REE) and some major elements. And the depleted elements vary with deposits, having generality and their own features. On a deposit scale, the positive anomalies of enriched elements and negative anomalies of depleted elements follow in a sequence to comprise regular anomaly models of spatial structures. The exploration in the Tongchang deposit in Jiangxi and Huitongshan deposit in Gansu suggests that anomaly models play a key role in the identification of mineral occurrences and deposits compared to one single enriched element anomaly. And the anomaly models exert a critical effect on the optimization of prospecting targets and their potential evaluation.

    • Lü Junchang

      2010,84(2):241-246, DOI:

      Abstract:

      A new boreopterid pterosaur: Zhenyuanopterus longirostris gen. et sp. nov. from the Yixian Formation of western Liaoning is erected, based on the complete skeleton with a skull and lower jaws preserved. It is characterized by: a large boreopterid pterosaur with a high number of teeth, where the anterior teeth are much larger than posterior ones; the length of the dorsal + sacral vertebrae is nearly half the length of the skull; ratio of the length of the humerus to metacarpal IV is approximately 91% and the, humerus, femur and third wing phalanx are all equal in length and the feet are specially small. It represents the largest boroepterid pterosaur discovered from western Liaoning and its surrounding areas so far

    • WANG Sufen, ZHANG Tingshan, ZHOU Jixian, HU Yu

      2017,91(1):320-340, DOI:

      Abstract:

      The distribution characteristics of the oil-water contact are the basis for the reservoir exploration and development and reserves evaluation. The reservoir with a tilted oil-water contact has a unique formation mechanism, and the understanding of its distribution and formation mechanism will directly affect the evaluations for the reservoir type, well deployment, selection of well pattern and type, determination of test section, and reserves evaluation. Based on the analysis of reservoir characteristics, petrophysical properties and geological structure in 40 reservoirs worldwide with tilted oil-water contacts, the progress of the research on the formation mechanisms of titled oil-water contacts is summarized in terms of the hydrodynamic conditions, reservoir heterogeneity, neotectonic movement and oil-gas exploitation. According to the formation mechanism of tilted oil-water contacts and the needs of exploration research, different aspects of research methods are summarized and classified, such as the calculation of equipotential surfaces for oil and water in the formation, analysis of formation pressure and analysis of reservoir physical properties and so on. Based upon statistical analysis, it is suggested that the degree of the inclination of the oil-water contact be divided based on the dip of oil-water contact (DipTOWC). The tilted oil-water contact is divided into three categories: large dip (DipTOWC≥55 m/km), medium dip (4 m/km≤DipTOWC<55 m/km), and small dip (DipTOWC<4 m/km). The classification and evaluation method can be combined with structure amplitude and reservoir property. The formation mechanism of domestic and international reservoirs with tilted oil-water contacts are summarized in this paper, which have important significance in guiding the exploration and development of the oilfield with tilted oil-water contacts, reserves evaluation, and well deployment.

    • Mahboobeh JAMSHIDI BADR, Fariborz MASOUDI, Alan S. COLLINS, Ali SORBI

      2012,86(1):48-64, DOI:

      Abstract:

      The Soursat metamorphic complex (SMC) in northwestern Iran is part of the Sanandaj–Sirjan metamorphic belt. The complex is composed of different metamorphic and plutonic rocks, but is dominated by metapelites composed of garnet, staurolite, kyanite, fibrolite, cordierite, and andalusite. Porphyroblasts in schists have the same fabric, and three stages of schistosity are present. The internal schistosity (Sn) inclusion trails are also offset by conjugate sets of extensional schistosity (Sn+1) and a second (Sn+2) that crenulates (Sn+1). Polyphase metamorphisms are present in the complex. Garnet, staurolite, kyanite, and fibrolite assemblage preserves conditions during the M1 metamorphic event. This assemblage yields a P–t estimate of 645±11°C and 6.5±0.5 kbar. Other samples of the central part of SMC contain cordierite and andalusite (M2) overgrowth that yields a P–t estimate of 532±33°C and 2.1±1.1 kbar.

    • ZHENG Yadong, ZHANG Qing, HOU Quanlin

      2015,89(4):1133-1152, DOI:

      Abstract:

      The essential difference in the formation of conjugate shear zones in brittle and ductile deformation is that the intersection angle between brittle conjugate faults in the contractional quadrants is acute (usually ~60°) whereas the angle between conjugate ductile shear zones is obtuse (usually 110°). The Mohr-Coulomb failure criterion, an experimentally validated empirical relationship, is commonly applied for interpreting the stress directions based on the orientation of the brittle shear fractures. However, the Mohr-Coulomb failure criterion fails to explain the formation of the low-angle normal fault, high-angle reverse fault, and the conjugate strike-slip fault with an obtuse angle in the σ1 direction. Although it is ten years since the Maximum-Effective-Moment (MEM) criterion was first proposed, and increasingly solid evidence in support of it has been obtained from both observed examples in nature and laboratory experiments, it is not yet a commonly accepted model to use to interpret these anti-Mohr-Coulomb features that are widely observed in the natural world. The deformational behavior of rock depends on its intrinsic mechanical properties and external factors such as applied stresses, strain rates, and temperature conditions related to crustal depths. The occurrence of conjugate shear features with obtuse angles of ~110° in the contractional direction on different scales and at different crustal levels are consistent with the prediction of the MEM criterion, therefore ~110° is a reliable indicator for deformation localization that occurred at medium-low strain rates at any crustal levels. Since the strain–rate is variable through time in nature, brittle, ductile, and plastic features may appear within the same rock.

    • CHI Guoxiang1, *, CHU Haixia1, Ryan SCOTT1, CHOU I-Ming2

      2014,88(4):1169-1182, DOI:

      Abstract:

      Raman peaks of various hydrates in the H2O-NaCl-CaCl2 system have been previously identified, but a quantitative relationship between the Raman peaks and XNaCl (i.e., NaCl/(NaCl+CaCl2)) has not been established, mainly due to the difficulty to freeze the solutions. This problem was solved by adding alumina powder to the solutions to facilitate nucleation of crystals. Cryogenic (-185oC) Raman spectroscopic studies of alumina-spiced solutions indicate that XNaCl is linearly correlated with the total peak area fraction of hydrohalite. Capsules of solutions made from silica capillary were prepared to simulate fluid inclusions. Most of these artificial fluid inclusions could not be totally frozen even at temperatures as low as -185oC, and the total peak area fraction of hydrohalite is not correlated linearly with XNaCl. However, the degree of deviation (DXNaCl) from the linear correlation established earlier is related to the amount of residual solution, which is reflected by the ratio (r) of the baseline “bump” area, resulting from the interstitial unfrozen brine near 3435 cm-1, and the total hydrate peak area between 3350 and 3600 cm-1. A linear correlation between DXNaCl and r is established to estimate XNaCl from cryogenic Raman spectroscopic analysis for fluid inclusions.

    • LI Jianjun, Martin G. LOCKLEY, ZHANG Yuguang, HU Songmei, MATSUKAWA Masaki, BAI Zhiqiang

      2012,86(1):1-10, DOI:

      Abstract:

      A large track site with multiple, well-preserved trackways of an Early Jurassic quadrupedal ornithischian dinosaur is the first report of Moyenisauripus-like trackways from Asia, herein named Shenmuichnus youngteilhardorum. The tracks occur in a clastic fluvial sequence in the Fuxian Formation in Shenmu County, Shaanxi Province, which is in the same general region as the discovery site of Sinoichnites,the first dinosaur track reported from China. Based on size and morphology, it is likely that Sinoichnites, which is now lost, also represents an ornithischian. The Shenmuichnus youngteilhardorum trackways show two modes of preservation: the first representing deeper tracks, with sediment rims, results in Deltapodus-like tracks, with indistinct pes digit traces and sub-circular manus traces, the second produces Moyenosauripus-like tracks, with clear tridactyl and pentadactyl digit traces in the pes and manus respectively. Thus the Shenmu trackways play a key role in resolving globally significant ichnotaxonomic problems surrounding the nomenclature of Sinoichnites, Moyenosauripus, Deltapodus and other named (Ravatichnus) and unnamed trackways from Asia, Africa and Europe. In addition they shed important light on the paleogeographical and paleoecological distribution of quadrupedal ornithischians in the Early Mesozoic. The track site has been the focus of a major excavation to transfer the trackways from their original remote location to the new Shenmu Museum, in Shenmu City. Other tracksites in the area which reveal Anomoepus, Grallator and the Deltapodus morphotype, together with Shenmuichnus and plant fossil evidence, suggest an Early Jurassic age for the tracksite.

    • DU Jianjun, LI Dunpeng, WANG Yufang, MA Yinsheng

      2017,91(1):76-92, DOI:

      Abstract:

      The Weihe Graben is not only an important Cenozoic fault basin in China but also a significant active seismic zone. The Huashan piedmont fault is an important active fault on the southeast side of the Weihe Graben and has been highly active since the Cenozoic. The well–known Great Huaxian County Earthquake of 1556 occurred on the Huashan piedmont fault. This earthquake, which claimed the lives of approximately 830000 people, is one of the few large earthquakes known to have occurred on a high–angle normal fault. The Huashan piedmont fault is a typical active normal fault that can be used to study tectonic activity and the associated hazards. In this study, the types and characteristics of late Quaternary deformation along this fault are discussed from geological investigations, historical research and comprehensive analysis. On the basis of its characteristics and activity, the fault can be divided into three sections, namely eastern, central and western. The eastern and western sections display normal slip. Intense deformation has occurred along the two sections during the Quaternary; however, no deformation has occurred during the Holocene. The central section has experienced significant high–angle normal fault activity during the Quaternary, including the Holocene. Holocene alluvial fans and loess cut by the fault have been identified at the mouths of many stream valleys of the Huashan Mountains along the central section of the Huashan piedmont fault zone. Of the three sections of the Huashan piedmont fault, the central section is the most active and was very active during the late Quaternary. The rate of normal dip–slip was 1.67–2.71±0.11 mm/a in the Holocene and 0.61±0.15 mm/a during the Mid–Late Pleistocene. As is typical of normal faults, the late Quaternary activity of the Huashan piedmont fault has produced a set of disasters, which include frequent earthquakes, collapses, landslides, mudslides and ground fissures. Ground fissures mainly occur on the hanging–wall of the Huashan piedmont fault, with landslides, collapses and mudslides occurring on the footwall.

    • K.V. BADHE, H.S. PANDALAI

      2015,89(3):715-725, DOI:

      Abstract:

      Re-equilibration of fluid inclusions in crystals takes place by loss or gain of solvents and solutes from fluid inclusions and by changes in their volumes. Volume change of fluid inclusions are primarily dictated by elastic properties and available slip planes of host crystals. In the present study, the phase-behavior of fluids entrapped in co-precipitated calcite and barite is studied. While calcite contains only biphase fluid inclusions, barite has predominantly monophase fluid inclusions. Fluid inclusion petrography, microthermometry and leachate analysis are used to establish the nature of entrapped fluids and entrapment temperature is substantiated through independent sulfur isotope geothermometry using coexisting barite and pyrite. Phase transitions in the monophase fluid inclusions in barite are explained in terms of over-pressuring of fluids in these fluid inclusions relative to fluids entrapped in calcite owing to the low bulk modulus of barite.

    • 2021,95(3):1056-1056, DOI: 10.1111/1755-6724.14310

      Abstract:

    • ZHANG Gang, WANG Xuben, FANG Hui, GUO Ziming, ZHANG Zhaobin, LUO Wei, CAI Xuelin, LI Jun, LI Zhong, WU Xing

      2015,89(2):531-541, DOI:

      Abstract:

      The Panxi region is located in the frontal zone of positive squeezing subduction and side squeezing shearing between the Indian plate and the Eurasian plate. The long-period magnetotelluric (LMT) and broadband magnetotelluric (MT) techniques are both used to study the deep electrical conductivity structure in this region; magnetic and gravity surveys are also performed along the profile. According to the 2-D resistivity model along the Yanyuan-Yongshan profile, a high-conductivity layer (HCL) exists widely in the crust, and a high-resistivity block (HRB) exists widely in the upper mantle in general, as seen by the fact that a large HCL exists from the western Jinpingshan tectonic zone to the eastern Mabian tectonic zone in the crust, while the HRB found in the Panxi tectonic zone is of abnormally high resistivity in that background compared to both sides of Panxi tectonic zone. In addition, the gravity and magnetic field anomalies are of high value. Combined with geological data, the results indicate that there probably exists basic or ultrabasic rock with a large thickness in the lithosphere in the Panxi axial region, which indicates that fracture activity once occurred in the lithosphere. As a result, we can infer that the high-resistivity zone in the Panxi lithosphere is the eruption channel for Permian Emeishan basalt and the accumulation channel for basic and ultrabasic rock. The seismic sources along the profile are counted according to seismic record data. The results indicate that the most violent earthquake sources are located at the binding site of the HRB and the HCL, where the tectonic activity zone is generally acknowledged to be; however, the earthquakes occurring in the HCL are not so violent, which reflects the fact that the HCL is a plastic layer, and the fracture threshold of a plastic layer is low generally, making high stress difficult to accumulate but easy to release in the layer. As a result, a higher number of smaller earthquakes occurred in the HCL at Daliangshan tectonic zone, and violent earthquakes occurred at the binding site of high- and low-resistivity blocks at the Panxi tectonic zone.

    主编 :侯增谦

    主管单位 :中国科学技术协会

    主办单位 :中国地质学会

    联系电话 :010-68999024

    国际标准刊号 :1000-9515

    国内统一刊号 :11-2001

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