南黄海盆地二叠系烃源岩孢粉相特征及其形成环境

以沉积环境控制烃源岩发育理论为指导,应用孢粉相分析方法,以南黄海盆地二叠系大隆组、龙潭组和栖霞组烃源岩层段为研究对象,对典型钻井剖面的孢粉及沉积有机屑进行系统的分析。根据沉积有机屑的丰度特征和组分类型,探讨三套烃源岩的形成环境,初步评价其生烃潜力。研究结果表明,利用孢粉相分析方法,可以有效地对高成熟海相烃源岩的生烃潜力和形成环境进行客观评价:栖霞组为缺氧远陆架沉积环境,以无定形有机质为主,水体分层缺氧,是烃源岩形成的有利环境;大隆组为缺氧和少氧的陆架环境,也较有利于烃源岩的形成,生烃潜力较栖霞组差;龙潭组煤质型有机质较为丰富,为充氧的陆架区,以陆源输入为主,沉积区水体较浅,含氧量高,不利于富氢烃源岩的形成。     

基于MapGIS的徐州市矿产资源潜力评价数据库建设

为了科学合理地对徐州市境内的矿产资源潜力进行评价,寻求地区经济与社会的可持续发展的资源优势,以现有资料为基础,对多源数据进行规范整理,统一空间坐标参数,利用MapGIS和Access软件,初步建立了图形数据属性数据相结合的徐州市基础矿产地质数据库。结合项目的需要,依据规范建设专题数据库,为开展区内现代矿产资源潜力评价工作奠定了基础。     

Generalized failure envelope for caisson foundations in cohesive soil: Static and dynamic loading

The response of massive caisson foundations to combined vertical (N), horizontal (Q) and moment (M) loading is investigated parametrically by a series of three-dimensional finite element analyses. The study considers foundations in cohesive soil, with due consideration to the caisson-soil contact interface conditions. The ultimate limit states are presented by failure envelopes in dimensionless and normalized forms and the effects of the embedment ratio, vertical load and interface friction on the bearing capacity are studied in detail. Particular emphasis is given on the physical and geometrical interpretation of the kinematic mechanisms that accompany failure, with respect to the loading ratio M/Q. Exploiting the numerical results, analytical expressions are derived for the capacities under pure horizontal, moment and vertical loading, for certain conditions. For the case of fully bonded interface conditions, comparison is given with upper bound limit equilibrium solutions based on Brinch Hansen theory for the ultimate lateral soil reaction. A generalized closed-form expression for the failure envelope in M–Q–N space is then proposed and validated for all cases examined. It is shown that the incremental displacement vector of the caisson at failure follows an associated flow rule, with respect to the envelope, irrespective of: (a) the caisson geometry, and (b) the interface conditions. A simplified geometrical explanation and physical interpretation of the associativity in M-Q load space is also provided. Finally, the derived failure envelope is validated against low (0.67 Hz) and high frequency (5 Hz) dynamic loading tests and the role of radiation damping on the response of the caisson at near failure conditions is unraveled.     

一种测震仪器数据流接入框架的设计与应用

为了满足对测震仪器的辅助性数据进行综合利用和交换共享的需要,通过分析地震数据采集器传输数据流的方式和特点,利用软件工程思想和面向对象的软件复用技术,建立了一种轻量级、可复用的应用框架,为面向测震仪器的数据接入程序设计提供了一种分布式、高性能、异步流水的体系结构。对框架的实现细节进行了详细阐述,并将框架成功应用于测震台站运行状态监视系统中,测试结果证明了框架的科学性、合理性和实用性,为框架的推广应用提供了典型示范。     

基础性地理国情监测的生产实践与应用思考

通过资料收集、数据生产获取了2005-2015 10年间四期地理国情监测成果,以此为研究对象,从监测要素流向,城市空间扩展,交通、水域、林草地变化等几个方面进行分析,得出了有价值的结论,再以其他资料进行验证,并对监测成果的应用进行探讨。     

通化盆地下白垩统烃源岩石油地质特征及生烃潜力研究

通化盆地是松辽盆地东部外围的油气远景区之一,烃源岩发育特征和生烃潜力等问题未知,制约着盆地基础油气资源研究和后续油气资源勘探部署工作。为揭示通化盆地下白垩统烃源岩生烃潜力和页岩油气的赋存状态,在盆地内部署通地1井,对岩芯样品进行系统取样,完成了暗色泥岩有机质丰度、类型和成熟度的测试工作。实验结果表明,通化盆地下白垩统亨通山组暗色泥岩有机质丰度较高,有机质类型以Ⅰ-Ⅱ1型为主,局部含有Ⅲ型,镜质组反射率分布范围为0.972%~1.127%,已进入大量生烃的成熟阶段;下桦皮甸子组暗色泥岩有机质丰度较高,有机质类型以Ⅰ型为主,局部含有Ⅱ和Ⅲ型,镜质组反射率在0.986%~1.399%之间,已进入大量生烃的成熟阶段。其地球化学特征和世界上许多页岩油气田的烃源岩有相似之处,综合研究表明通化盆地下白垩统具有较好的常规油气和页岩气生成潜力。     

Delineation of potential exploration targets based on 3D geological modeling: A case study from the Laoangou Pb-Zn-Ag polymetallic ore deposit,China

The Laoangou Pb-Zn-Ag polymetallic ore deposit (LAG) is a hydrothermal vein-type deposit in the East Qinling polymetallic metallogenic belt, which is controlled by NW-, NE- and nearly SN-trending faults and mainly hosted in the dolomite marble of Meiyaogou and Baishugou formations within the Luanchuan ore district (LOD). Although district-scale metallogenic prediction related to the Pb-Zn-Ag deposits in the LOD has been attempted, there have been no studies to formulate a detailed deposit-scale metallogenic prediction of the Pb-Zn-Ag deposit in 3D space. Here we selected the LAG to formulate a metallogenic prediction model for Pb-Zn-Ag deposit based on data from 1:10,000 scale geological map, and 66 boreholes and 39 sections of exploration lines on 1:1000 scale, to extract the salient spatial features of the deposit. We apply ordinary weights and weighted weights of evidence, followed by boosted weights of evidence, logistic regression and information entropy for integrating the features of the ore deposit for exploration targeting. The C–V fractal method is applied to classify the probabilities. Accordingly, three levels of exploration targets are delineated: the first level targets are mainly distributed in the periphery of known orebodies (M2, M3, II-3 and VI), which are also located in the ore-controlling strata and fault zones; the second level targets are located in the region of known orebodies, indirectly confirming that the prediction result is reliable; and the third level targets, which are mainly located at the contact between ore-controlling strata and metagabbro bodies, offer new targets for exploration in this ore district. Combining our results obtained in this study with those in previous studies, we provide some guidelines for exploration targets in the Pb-Zn-Ag deposits in the LOD, which might help in more effectively delineating the target zones.     

Petrography,chemical composition,and Raman spectra of chrome spinel: Constraints on the diamond potential of the No. 30 pipe kimberlite in Wafangdian,North China Craton

Conventional diamond exploration seldom searches directly for diamonds in rock and soil samples. Instead, it focuses on the search for indicator minerals like chrome spinel, which can be used to evaluate diamond potential. Chrome spinels are preserved as pristine minerals in the early Paleozoic (∼465 Ma), hydrothermally altered, Group I No. 30 pipe kimberlite that intruded the Neoproterozoic Qingbaikou strata in Wafangdian, North China Craton (NCC). The characteristics of the chrome spinels were investigated by petrographic observation (BSE imaging), quantitative chemical analysis (EPMA), and Raman spectral analysis. The results show that the chrome spinels are mostly sub-rounded with extremely few grains being subhedral, and these spinels are macrocrystic, more than 500 µm in size. The chrome spinels also have compositional zones: the cores are classified as magnesiochromite as they have distinctly chromium-rich (Cr₂O₃ up to 66.56 wt%) and titanium-poor (TiO₂ < 1 wt%) compositions; and the rims are classified as magnetite as they have chromium-poor and iron-rich composition. In the cores of chrome spinels, compositional variations are controlled by Al³⁺-Cr³⁺ isomorphism, which results in a strong Raman spectra peak (A_1g mode) varying from 690 cm⁻¹ to 702.9 cm⁻¹. In the rims of chrome spinel, compositional variations result in the A_1g peak varying from 660 cm⁻¹ to 672 cm⁻¹. The morphology and chemical compositions indicate that the chrome spinels are mantle xenocrysts. The cores of the spinel are remnants of primary mantle xenocrysts that have been resorbed, and the rims were formed during kimberlite magmatism. The compositions of the cores are used to evaluate the diamond potential of this kimberlite through comparison with the compositions of chrome spinels from the Changmazhuang and No. 50 pipe kimberlites in the NCC. In MgO, Al₂O₃ and TiO₂ versus Cr₂O₃ plots, the chrome spinels from the Changmazhuang and No. 50 pipe kimberlites are mostly located in the diamond stability field. However, only a small proportion of chrome spinels from No. 30 pipe kimberlite have same behavior, which indicates that the diamond potential of the former two kimberlites is greater than that of the No. 30 pipe kimberlite. This is also supported by compositional zones in the spinel grains: there is with an increase in Fe³⁺ in the rims, which suggests that the chrome spinels experienced highly oxidizing conditions. Oxidizing conditions may have been imparted by fluids/melts that have a great influence on diamond destruction. Here, we suggest that chrome spinel compositions can be a useful tool for identifying the target for diamond potential in the North China Craton.     

Geological characteristics and analysis of known and undiscovered graphite resources of China

Graphite is one of the most essential non-metallic minerals with a wide variety of uses, and is an important commodity used in the emerging industry of China. Graphite is sourced from 170 mine areas in China from 25 provinces. This contribution is on a study of 15 regions in China with known graphite resources based on the spatial and temporal analyses of the regional metamorphic, contact metamorphic, and hydrothermal types of graphite. The knowledge gained on the metallogenesis of graphite in China is used to develop a model for choosing prospective regions for graphite, and to target areas for detailed exploration. It outlined 28 prediction areas with predicted graphite resources of about 1.63 billion tonnes to a maximum depth of 500 m in the Heilongjiang, Jilin, Liaoning, Shandong, Inner Mongolia and Hunan provinces. And of these, the predicted flake graphite resources in the Heilongjiang Province has been totalling almost a billion tonnes representing almost 60% of China’s graphite resource. As a result of this study, it is concluded that graphite has been formed during restricted periods of time, with the regional metamorphic type being the main style present in China.     

Petrogenesis and metallogenic potential of the Jurassic porphyries in the northwest Zhejiang Province,South China: insights from SHRIMP zircon geochronology,geochemistry, and Sr–Nd–Hf isotopes of the Huangbaikeng ore-bearing porphyries

The northwest Zhejiang Province is a key domain for providing deep insight into the crust–mantle interaction and tectonic evolution of the South China block. In this paper, we collect geochemical, geochronological, and isotopic data of the Jurassic porphyries in this region, and investigated the Huangbaikeng ore-bearing porphyry in the Tongcun Mo–Cu deposit, using it as an example to uncover the porphyry petrogenesis and evaluate their metallogenic potential. Two varieties of the Huangbaikeng porphyry were distinguished: the medium- to coarse-grained type and medium- to fine-grained type. Zircon Sensitive High-Resolution Ion Microprobe U–Pb dating indicates that they were emplaced at 161.8 ± 2.8 and 162.7 ± 3.5 Ma, respectively, which are consistent with the molybdenite Re–Os ages of 163.9–161.8 Ma. The inherited zircons age spectrum significantly recorded a series of geological events, for example, assembly and breakup of the Columbia and Rodinia supercontinent, and the Triassic collision of Yangtze and North China blocks. Whole rock Sr–Nd and Jurassic zircon Hf isotopic data yield mostly negative ε_Hf(t) values (0.5 to ?8.4) and ε_Nd(t) values (?0.79 to ?4.82). Besides the Huangbaikeng porphyry, all the Jurassic porphyries in the northwest Zhejiang Province have a wide range of SiO₂ contents (76.78–60.91 wt.%). They do not contain typical aluminous minerals (e.g. cordierite and garnet), and are mainly metaluminous to weakly peraluminous with high Na₂O, low FeO^T/MgO, and Zr + Nb + Ce + Y concentrations in composition. They thus fit the I-type granite definition. Some major and trace elements show strong correlations with SiO₂, possibly indicating extensive fractional crystallization during their magma evolution. Tectonic discriminations imply that these plutons were likely formed in a volcanic arc regime possibly related to subduction of the Palaeo-Pacific plate. Sr–Nd–Hf isotopic data suggest a mixed source of the Mesoproterozoic crust and 30–50% mantle components. Compared with the adjacent Dexing Cu-bearing porphyies, which have more positive ε_Hf(t) and ε_Nd(t) values with more significant mantle components (55–70%), the Jurassic porphyries in the northwest Zhejiang Province probably lack metallogenic potential to form a giant porphyry copper deposit as Dexing.