南大巴山前陆冲断褶皱带断裂流体地球化学特征及构造保存研究     

周业鑫  丁俊  余谦  王剑  熊国庆  门玉澎  熊小辉  邓奇 《地质学报》2017,91(6):1169-1180

南大巴山前陆构造带位于城口断裂与铁溪-巫溪断裂之间,为研究该构造带断裂对烃类运移及构造对页岩气保存的影响,本文对该构造带内断裂流体的碳氧同位素和流体包裹体进行了测试分析。测试结果显示,研究区断裂流体碳氧同位素整体较围岩更为分散,δ~(13)C_(PDB)介于-2.9‰~3.9‰之间,属正常海相碳酸盐层的碳同位素值,坪坝断裂附近δ~(13)C_(PDB)呈明显亏损,具外来流体混合的特征。流体包裹体为含烃的气液二相盐水包裹体,气相成分为CH_4,液相为H_2O。包裹体均一温度以城口断裂附近最高,主要为311~336℃,频率峰值温度为328℃;往南叠瓦带流体均一温度主要位于183~269℃之间,峰值为230℃,断褶带峰值为213℃,滑脱褶皱带为170℃,整体表现为向盆内方向降低。盐度主要为4.43%~8.6%NaCl。研究表明,城口断裂作为大巴山构造带南北分界的主干断裂,古流体的形成温度和热演化程度最高,且从盆地向北至城口断裂,各构造带流体的热演化程度、成岩温度、古流体压力均逐渐升高,说明随着构造活动的增强,构造带中的流体更为活跃,持续时间更长,导致流体形成的深度和温度变化较大。构造带内的流体总体上形成于封闭体系,在主构造应力的驱动下,盆地深部含烃流体沿断裂向浅部运移,并与浅部地层流体发生混合,运移通道整体处于封闭状态;而构造带内的一些次级断裂,因其形成的时间以及向下延伸的深度不足以触及下古生界烃源岩层,因此其对流体封闭性的影响有限。  相似文献   

Early Cretaceous porphyry copper mineralization in Northeast China: the Changfagou example     

Yong Zhang  Shu–Wen Xing  Chao Li  Shi–Fu Liang  Zheng–Tao Yu  Xiao–Hui Du 《International Geology Review》2017,59(2):185-203

The Changfagou Cu deposit is a newly discovered porphyry deposit located in the southern Jilin Province of Northeastern China, on the northeastern margin of the North China Craton. To better understand the formation of the Cu deposit, we report the zircon U–Pb and molybdenite Re–Os dating, and Sr-, Nd-, and Hf- isotopic data of the granite porphyry. LA-ICP-MS dating of zircon grains from two mineral zones in the granite porphyry yield ages of 115.7 ± 0.8 and 115.3 ± 0.6 Ma, which is interpreted as the emplacement age of the granite porphyry. The molybdenite Re–Os model ages of 112.5 to 113.8 Ma, an isochron age of 113.3 ± 1.3 Ma, and a weighted mean model age of 113.0 ± 0.7 Ma, which represents the age of the Cu mineralization quite well. The Changfagou granite porphyry samples lack amphibole and muscovite, and are compositionally characterized by high SiO₂, high Na₂O+K₂O, and low P₂O₅, enriched in some Rb, Th, U, and Pb, and depleted in Nb, Ta, Ti, P, and Eu. Mineralogical and geochemical features suggest that the Changfagou granite porphyry samples are slightly peraluminous and are of highly fractionated I-type granitoids. The granitic rocks also have relatively high (⁸⁷Sr/⁸⁶Sr)_i (0.71199 to 0. 71422), and both low εNd(t) (?14.56 to ?13.19) and εHf(t) values (?14.916 to ?8.644), which suggest that Changfagou granite porphyry are derived from mixed sources of crustal and mantle, and diagenesis and mineralization were possibly related to the switch in subduction direction of the Palaeo-Pacific Plate in the late phase of Early Cretaceous.  相似文献   

Decoding Neoarchaean to Palaeoproterozoic tectonothermal events in the Rangnim Massif,North Korea: regional correlation and broader implications   总被引：1，自引：0，他引：1  

Xiaohui Zhang  Yanbin Zhang  Mingguo Zhai  Fuyuan Wu  Quanlin Hou  Lingling Yuan 《International Geology Review》2017,59(1):16-28

Any knowledge about Archaean to Palaeoproterozoic magmatic and metamorphic events in North Korea has the potential to make a significant difference to our understanding of the early tectonic configuration and evolution of East Asia. This zircon U–Pb dating and Hf isotopic study documents multiple Neoarchaean to Palaeoproterozoic tectonothermal events from the meta-igneous complex in the Machollyong ‘Group’ of the Rangnim Massif. Two tonalitic-trondjemitic gneiss samples record a crystallization age of meta-igneous protoliths at ca. 2.56 Ga and multiple migmatization and metamorphism from 2.52 to 1.85 Ga. A meta-dolerite sample yields a magmatic emplacement age of ca. 1.83 Ga. In situ zircon Hf isotopic data indicate that most zircons from the gneiss samples have ε_Hf(t) values from –16.9 to + 3.1 and crustal model ages from 2.84 to 3.73 Ga, whereas magmatic zircons from the meta-dolerite dike record ε_Hf(t) values from –5.2 to + 5.2 and model ages of 2.05–2.44 Ga. The first-recognized Neoarchaean tonalitic-trondjemitic migmatite complex in the Rangnim Massif, together with previously identified tonalitic-trondhjemitic-granodioritic (TTG) rocks in the Rimjingang Belt and the coeval counterparts in western Gyeonggi massif, represents the oldest crustal nuclei in the Korean Peninsula. The multiple tectonothermal events in this study present reliable evidence not only for attesting to consanguinity of the basement between the Korean Peninsula and the North China Craton but also for defining the influence scope of the late Palaeoproterozoic orogeny in the Korean Peninsula.  相似文献   

Detecting hotspots of urban residents’ behaviours based on spatio-temporal clustering techniques     

Pengdong Zhang  Min Deng  Yan Shi  Ling Zhao 《GeoJournal》2017,82(5):923-935

Hotspots are regions where the number of spatial objects is obviously high within the time intervals. As the behaviours of urban residents are considered as a typical kind of spatio-temporal pattern, the detection of hotspots of urban residents’ behaviours appears necessary, since important information might be discovered in hotspots. In this paper, we propose an approach to detect the spatio-temporal hotspots of urban residents’ behaviours. This approach is validated based on the GPS data of floating cars of a city in southern China. The approach consists of four main steps: first, the effective spatio-temporal trajectories and the important characteristic points contained in each trajectory are extracted from the GPS data; second, the spatio-temporal clusters are generated by clustering the characteristic points based on a kernel density estimation algorithm; third, the spatio-temporal hotspots are detected by filtering the spatio-temporal clusters with high densities; last, the detected hotspots are analysed and interpreted. The results show that the proposed approach is effective and useful in detecting hotspots of urban residents’ behaviours.  相似文献   

The contingency of medicare physician spending on population densities and sizes     

Yunjie Song  Xun Shi 《GeoJournal》2017,82(3):597-608

The exploration of the spatial association between Medicare physician spending and population densities and sizes could possibly facilitate the investigation of the causal mechanisms beneath the variation in medical care. We acquired the U.S. Medicare physician expenditures and regional demographic and geographic data in 2006 from the Dartmouth Atlas of Health Care. Six geographic units—states, counties, Hospital Referral Regions, Hospital Service Areas, Metropolitan Statistical Areas, and state non-Metropolitan Statistical Areas—were used as units of study. Pearson correlation analysis, multivariable regression, and partial correlation analysis were employed. Among six geographic units, Pearson correlation coefficients between Medicare physician expenditures and logarithmic population densities ranged from 0.42 to 0.63 (p < 0.05 for all), and between the expenditures and logarithmic population sizes from 0.31 to 0.65 (p < 0.05 for all). When population health, differential demand, market structure, and data reporting bias were controlled, population densities and sizes were positively associated with Medicare physician expenditures in most models. Population densities and sizes could explain considerable amounts of regional variation in Medicare physician spending. We concluded that Medicare physician spending was contingent on population densities and sizes. Because population densities and sizes are produced by more fundamental qualities such as natural environments and resources and thus are not easily manipulated, they are suggestive in health policy studies. Further research might investigate population distribution associated properties such as geographic distribution of health care resources, spatial dynamics of medical technology distribution, and cultural and psychological factors.  相似文献   

钾玄质系列岩石的研究现状     

贾小辉  王晓地  杨文强  牛志军 《地质论评》2017,63(6):1587-1601

钾玄质系列岩具有特殊的矿物学和地球化学特征,并具有重要的构造及成矿意义,自命名以来备受关注,但仍有许多问题存在较大争议,如岩石类型扩大化、是否存在壳源成因、板内环境如何判别等等。本文从以下几方面对钾玄质系列岩进行了系统总结:(1)作为一个独立的岩石系列,钾玄质系列岩仍缺失明确有效的岩石学、矿物学和地球化学等判别指标,相对统一的标准亟待建立;(2)与岛弧有关的钾玄质系列岩表现为高度富集大离子亲石元素和轻稀土元素,具有显著地TNT异常(Ta—Nb—Ti);大洋板内钾玄质系列岩具有典型的洋岛玄武岩(OIB)的微量元素特征;大陆板内钾玄质系列岩石兼具岛弧型和OIB型微量元素特征;(3)低硅钾玄质岩(SiO_2不大于63%)应当主要源于地幔源区,高硅钾玄质岩主要源于地壳源区,但更多情况下是二者的混合。  相似文献   

三维成矿预测多源地学空间数据库建设——以宁芜盆地钟姑矿田为例          下载免费PDF全文

张明明李晓晖  唐敏慧马良贾  蔡胡训宇廖宝胜袁 峰 《地质科学》2017,(3):743-754

大数据是海量、高增长率和多样化的信息资产,是未来找矿靶区预测的不可或缺的技术。大数据-三维成矿预测研究面临机遇与挑战,其涉及的地学大数据除了数据来源众多、比例尺不同、数据量大、非结构化管理、时效性强、空间数据与非空间数据协同管理等复杂特点外,还必须具有适应进行三维建模及空间分析的数据结构。本文分析了地学空间大数据的特点,对多源地学综合信息的管理需求进行研究,参考国家及行业标准,建立了可满足三维成矿预测需求的多源地学空间数据库模型,并依据实际划分为勘查控制钻孔地质数据库、空间属性数据库和地球物理数据库,各数据库可在多源地学空间索引库的支持下协同工作。本文以大数据应用的典型实例--钟姑矿田作为研究对象,系统收集了矿田内勘查成果资料,建立了钟姑矿田多源地学空间数据库,并在此基础上进行了控矿要素的有效提取,可进一步支持三维成矿预测。研究结果表明,本文提出的多源地学空间数据库可有效管理地学空间大数据,是大数据-三维成矿预测的重要解决方案,是进行三维成矿预测的重要数据支持。  相似文献   

Diagenesis and hydrocarbon emplacement in the Upper Triassic Yanchang Formation tight sandstones in the southern Ordos Basin,China     

H. Chen  C. Chen  W. Yin  Q. Zhang  R. Shi 《Australian Journal of Earth Sciences》2017,64(7):957-980

The Upper Triassic Yanchang Formation in the southern Ordos Basin is a tight sandstone but productive hydrocarbon exploration target. A variety of analyses, including thin-sections, cathodoluminescence (CL), scanning electron microscope (SEM), X-ray diffraction (XRD), fluorescence, isotope and fluid inclusion, have been used to analyse the reservoir petrology and diagenesis to understand the evolution of reservoir porosity. The sandstones are mostly feldspathic litharenites and lithic arkoses with low porosities (7.6% on average) and extremely low permeabilities (0.49 mD on average). A complex diagenetic alteration history of the reservoir caused different kinds of reduction in reservoir porosity. The carbonate cements are sourced from adjacent organic-rich mudstone and precipitated with a higher content near the edges of sandstone units and a lower content at the centres of sandstone units, resulting in two different diagenetic evolution paths. The analysis of porosity evolution history and hydrocarbon emplacement produced the following conclusions: (1) during the eodiagenesis period, mechanical compaction reduced the primary porosity dramatically from 40 to 19%; and (2) during the mesodiagenesis period, the first-phase oil charged the reservoir (porosity ranging from 14 to 19%) as bitumen along detrital grains forming a preferential pathway for subsequent oil emplacements. In the second-phase of oil charge, the reservoir porosity ranged from 9 to 14% limiting water–rock reactions. During the third-phase of oil charge, porosity of the reservoir remained at 9%. In general, the densification period (with a porosity close to 10%) of the reservoir occurs at the same time as the major oil emplacement and may be an explanation for the low oil saturation of the Chang 8 tight sandstone.  相似文献   

Experimental research on the effect of slope morphology on bank collapse in mountain reservoir     

Ji  Feng  Shi  Yuchuan  Zhou  Huixing  Liu  Haiming  Liao  Yi 《Natural Hazards》2017,87(1):165-184

Farmers along the Amazon River each year face multiple natural hazards that threaten crop production and limit the potential for agricultural development of the expansive floodplain and active channel. In this paper we report the findings of a study of natural hazard-related risk associated with rice production on silt bars in the active channel of the Amazon River near Iquitos, Peru. Data were gathered in four rice producing communities in 2014 using household surveys (n = 83 households), focus group discussions, surveying of land elevations along the Amazon River, and interpretation of remote sensing imagery. The probability, extent, and severity of rice crop shortfalls were estimated for recent production years and the economic losses to farming households were also assessed. Our findings point to a very high risk of crop shortfalls due to natural hazards, suggesting that a good year brings rice farmers bounty and a bad year, near penury. River stage reversals (repiquetes) and edaphic conditions were found to be more problematic than the often cited hazard of high and/or early floods. Also surprisingly, farmers’ perceptions of hazards and risk diverged markedly from actual shortfalls experienced during the production years studied. Our results provide the first quantitative estimates of risk due to the multiple natural hazards along the Amazon River and point to the need to assist lowland farmers with risk mitigation so as to unlock the considerable potential of Amazon floodlands for agricultural production.  相似文献   

Modeling coastal tsunami hazard from submarine mass failures: effect of slide rheology,experimental validation,and case studies off the US East Coast     

Grilli  Stéphan T.  Shelby  Mike  Kimmoun  Olivier  Dupont  Guillaume  Nicolsky  Dmitry  Ma  Gangfeng  Kirby  James T.  Shi  Fengyan 《Natural Hazards》2017,86(1):353-391

Natural Hazards - We perform numerical simulations to assess how coastal tsunami hazard from submarine mass failures (SMFs) is affected by slide kinematics and rheology. Two types of two-layer SMF...  相似文献