辽东铀成矿带连山关地区韧性剪切带与铀成矿作用     

吴迪  刘永江  李伟民  常瑞虹 《岩石学报》2020,36(8):2571-2588

连山关地区位于华北克拉通北缘铀成矿省辽东铀成矿带，已知铀矿床（点）均发育在韧性剪切带附近。为了解韧性剪切带运动学、几何学构造变形机制及与铀矿的关系，本文以连山关岩体周缘韧性剪切带为研究对象，通过野外宏观调查和室内微观研究相结合的研究方法，探讨构造变形期次、韧性剪切带形成机理及其对铀成矿的控制作用。研究表明：连山关岩体周缘发育的韧性剪切带与近南北向挤压构造变形有关，其右行韧性剪切带应变类型为压扁应变，属于一般压缩-平面应变范围，Flinn指数K值在0.19~0.69之间，岩石类型属于S/SL型构造岩。研究区内铀矿体均为隐伏盲矿体，主要赋存于沿着连山关岩体和辽河群接触带右行剪切作用形成的背斜褶皱核部，和北东东向断裂关系密切。综合分析认为，连山关岩体南缘北西向韧性剪切带为一级控矿构造，是区内铀矿热液运移的通道，而剪切带边部的晚期北东东向断裂则是铀矿储存空间；铀源可能来自于太古宙古风化壳，并在大型韧性剪切活动（提供热液运移通道）和基性脉岩侵入（提供热源和还原剂）等综合因素作用下运移、富集成矿。  相似文献   

Did the “Autochthonous” European foreland of Corsica Island (France) experience Alpine subduction?     

Maria Di Rosa  Chiara Frassi  Michele Marroni  Francesca Meneghini  Luca Pandolfi 《地学学报》2020,32(1):34-43

Despite the important role played by the Sardinia‐Corsica block in the reconstruction of the Western Mediterranean geodynamics, the extent of involvement of the “Autochthonous” European margin exposed in Corsica (France) (i.e., Hercynian Corsica) in the Alpine orogeny remains uncertain. Stratigraphic and sedimentological studies in the post‐Variscan deposits on the Hercynian Corsica are scarce and even scarcer are the structural and metamorphic constraints. To face these uncertainties, we present new stratigraphic, structural and metamorphic data from the area of Razzo Bianco, Central Corsica, where a complete sequence belonging to the European continental margin is exposed. Field and structural investigations demonstrate that the sequence represents the easternmost edge of the downgoing European plate. Metamorphic studies on the Eocene deposits indicate that the margin was buried at depth up to blueschist facies conditions and, subsequently, it was progressively exhumed mainly through the activation of oblique top‐to‐the NW shear zones.  相似文献   

Chemical and mineralogical characterization of the Mineo (Sicily,Italy) pallasite: A unique sample          下载免费PDF全文

A. Zucchini  M. Petrelli  F. Frondini  C. M. Petrone  P. Sassi  A. Di Michele  S. Palmerini  O. Trippella  M. Busso 《Meteoritics & planetary science》2018,53(2):268-283

The Mineo pallasite is characterized here for the first time. The only 42 g still available worldwide is part of the collection of the Department of Physics and Geology, University of Perugia. A multianalytical approach was used, joining field-emission scanning electron microscopy, Raman analysis, X-ray powder diffraction, electron-probe microanalysis, and laser ablation inductively coupled plasma mass spectrometry. Results highlighted that (1) the Mineo pallasite belongs to the Main Group pallasites; (2) the silicate component is essentially olivine, with no pyroxene component; (3) the olivine chemical composition varies in terms of both iron and trace elements; (4) the metal phase is essentially kamacite with the taenite mainly found in the plessite structure; (5) phosphide phases are present as schreibersite and barringerite. The observed compositional variability in olivines as well as their occurrence as both angular and rounded crystals suggest that the Mineo pallasite could have been derived from a large impact of a differentiated parent body with a larger solid body. The resulting pallasite conglomerate consists of the compositionally different olivines, likely coming from different areas of the same differentiated parent body, and the residual molten Fe-Ni.  相似文献   

全球气候变化下南海诸岛保护优先区识别分析   总被引：3，自引：1，他引：2  

左秀玲  苏奋振  张宇  吴文周  吴迪 《地理学报》2020,75(3):647-661

全球变化下,珊瑚礁保护区是保护生物多样性、增强珊瑚礁对气候变暖抵抗力的有效方式,而维持珊瑚礁弹性是其核心内容。针对珊瑚礁最具有威胁性的热压力因子,基于南海1982—2009年卫星观测海表面温度（SST）数据和CMIP5加拿大地球系统模式CanESM2模型预估的2006—2100年南海SST数据构建热压力强度模型,从维持珊瑚礁弹性的角度识别IPCC RCP 4.5和RCP 8.5情景下南海诸岛保护优先区。结果表明：RCP 4.5和RCP 8.5情景下13%左右的南海诸岛珊瑚礁识别为保护优先区。根据热压力强度与珊瑚抵抗力及避难所关系,西沙群岛七连屿和晋卿岛近年观测与未来预估的热压力强度均比较低,在保障其服务功能的基础上建议实施完全保护;东沙群岛东沙环礁和中沙环礁排洪滩近年观测急性热压力强度较高但未来预估热压力强度较低,建议实施50%禁止利用保护;中沙群岛黄岩岛近年观测和未来预估的急性热压力强度均比较低,建议实施50%多用途保护。南沙群岛有14%左右的珊瑚礁识别为保护优先区,根据其热压力强度可实施30%~100%禁止利用保护或30%~50%多用途保护。RCP 4.5和RCP 8.5情景下的南海诸岛保护优先区及保护对策,可为维持珊瑚礁生态弹性及应对全球气候变化提供重要的参考价值。  相似文献   

河北武城凸起地热田地热地质特征     

王迪  汪新伟  毛翔  武明辉  刘慧盈  张瑄  王婷灏 《地学前缘》2020,27(3):269-280

在“雄县模式”和环境压力的双重驱动下,河北地区已形成我国最大的地热供暖城市群。因此,研究武城凸起地热田地热地质特征,对河北省故城县地热开发具有重要的指导意义。本文通过测井、地震和区域地质资料,结合水化学特征、同位素测试结果的分析,系统分析了地热田的不同类型热储展布、储集层物性、地下热水补给来源和循环路径特征,并精细评价了地热资源量。结果表明武城凸起地热田热储类型主要为馆陶组砂岩热储和奥陶系岩溶热储。砂岩热储区域稳定分布,主要产水层为下馆陶组,底板埋深1 200~1 600 m,单井出水量79~123 m³/h, 井口水温52~54 ℃;岩溶热储有利区带主要分布在寒武—三叠系卷入的背斜核部,呈南北向带状展布,主要产水层为上马家沟组、下马家沟组和亮甲山组,顶板埋深2 100~2 900 m,单井出水量75~98 m³/h,井口水温82~85 ℃。地下热水来源为西部太行山脉和北部燕山山脉,热水沿着NE-SW向断裂破碎带和岩溶不整合面向上水平运移进入浅层热储,通过沧县隆起和邢衡隆起在武城凸起汇集,形成中低温地热田。地下热水质类型为Cl-Na型,最大循环深度为2 822.5~3 032.5 m,¹⁴C测年表明砂岩热储和岩溶热储年龄分别为21 ka和32 ka。明化镇组和石炭—二叠系分别为两套热储的直接盖层。武城凸起地热田地热资源量分层精细评价结果表明,热储地热资源量合计4.86×10¹⁰ GJ,折合标煤16.6×10⁸ t。年可开采地热资源量可满足供暖面积1.1×10⁸ m²,市场开发潜力巨大。  相似文献   

孟加拉湾及其毗邻海域中尺度涡旋活动的冬、夏季差异          下载免费PDF全文

黄挺  周锋  田娣  张家赢 《海洋学研究》2020,38(3):21-30

基于1993—2017年从卫星高度计资料中识别出来的中尺度涡轨迹数据集,对冬、夏季孟加拉湾涡旋的源地和性质进行了研究。研究表明孟加拉湾西部、安达曼海和孟加拉湾通往赤道的出口处的中尺度涡旋活动呈现显著的季节性差异。安达曼海在冬、夏季从北往南中尺度涡旋分别以“反气旋涡-气旋涡-反气旋涡”和“气旋涡-反气旋涡-气旋涡”的格局分布。不同源区涡旋的季节性生长过程有明显差异。孟加拉湾西部的涡旋在夏季生长迅速但消散缓慢,斯里兰卡冷涡生长缓慢但消散迅速。不同源区涡旋半径和振幅大小有不同的特征。孟加拉湾西部,无论冬、夏季,反气旋涡的振幅、半径都比气旋涡大;夏季季风漂流区,气旋涡半径比反气旋涡小但是振幅比反气旋涡大;安达曼海内无论冬、夏季都是最北侧聚集区涡旋的半径和振幅最大。孟加拉湾内生命史为30~40 d的涡旋数量最多,生命史在100 d以上的涡旋主要分布在孟加拉湾西部。  相似文献   

Rill flow resistance law under equilibrium bed‐load transport conditions     

Costanza Di Stefano  Alessio Nicosia  Vincenzo Pampalone  Vincenzo Palmeri  Vito Ferro 《水文研究》2019,33(9):1317-1323

In this paper, a recently deduced flow resistance equation for open channel flow was tested under equilibrium bed‐load transport conditions in a rill. First, the flow resistance equation was deduced applying dimensional analysis and the incomplete self‐similarity condition for the flow velocity distribution. Then, the following steps were carried out for developing the analysis: (a) a relationship (Equation  13 ) between the Γ function of the velocity profile, the rill slope, and the Froude number was calibrated by the available measurements by Jiang et al.; (b) a relationship (Equation  17 ) between the Γ function, the rill slope, the Shields number, and the Froude number was calibrated by the same measurements; and (c) the Darcy–Weisbach friction factor values measured by Jiang et al. were compared with those calculated by the rill flow resistance equation with Γ estimated by Equations  13 and 17 . This last comparison demonstrated that the rill flow resistance equation, in which slope and Shields number, representative of sediment transport effects, are introduced, is characterized by the lowest values of the estimate errors.  相似文献   

The potential of FAST in detecting celestial hydroxyl masers and related science topics     

Jiang-Shui Zhang  Di Li  Jun-Zhi Wang  Qing-Feng Zhu  Juan Li 《天文和天体物理学研究(英文版)》2019,(2)

The Five-hundred-meter Aperture Spherical radio Telescope(FAST) will make contributions to studies of Galactic and extragalactic masers. This telescope, with construction finished and now undergoing commissioning, has an innovative design that leads to the highest sensitivity of any single dish radio telescope in the world. FAST's potential for OH megamaser research is discussed, including the sky density of masers detectable in surveys. The scientific impact expected from FAST maser studies is also discussed.  相似文献   

长江下游区域地温场特征及其能源意义     

朱戈  刘绍文  李香兰  吴迪 《地学前缘》2020,27(1):25-34

区域地热特征及深部温度估算对于油气勘探和地热能资源评价和开发利用具有重要意义,长江下游地区是我国东部经济社会高度发达的地区,其能源需求大,区域热状态研究能为该区地热资源评价提供关键约束。通过整合长江下游地区已有的温度数据和实测岩石物性参数,勾勒出该区的现今地温场特征,并进一步估算其1 000~5 000 m埋深处的地层温度。研究表明,长江下游地区现今地温梯度为16~41 ℃/km,且以18~25 ℃/km居多,苏北盆地区呈现高地温梯度。大地热流值为48~80 mW/m²,其均值为60 mW/m²,表现为中等的地热状态,有利于油气和地热能形成。此外,长江下游地区深部地温估算表明,1 000 m埋深处的温度范围为30~54 ℃,2 000 m时温度范围为50~95 ℃,3 000 m时温度范围为65~130 ℃,4 000 m时温度范围为80~170 ℃,5 000 m时温度范围为100~210 ℃。区域深部地温的展布趋势呈NE向,高温区域集中在安徽南部和江苏东北部。结合60 ℃和120 ℃等温线的埋深分布及区域地质、地球化学和地热特征,初步探讨了该区油气与地热资源的有利区带及其相应的开发利用类型。  相似文献   

Bibliometric Analysis of Research Progress on Coastal Surface Water and Groundwater Interaction     

Tianzheng Cao  Dongmei Han  Xianfang Song  Wei Liu  Di Du 《地球科学进展》2020,35(2):154-166

The interactions among surface water, groundwater and seawater are closely related in the coastal area with complex hydrological conditions. A series of impacts from human activities and climate change are also more significant in this region. In order to understand the key knowledge and research status of surface water and groundwater interaction in coastal area, it is a useful method to analyze literatures in this research scope in the core database of Web of Science by using CiteSpace. The research achievements in this field were systematically sorted and potential research hotspots were explored, which may provide references for subsequent researches. The results show the following. \mathrm{①} The number of highly cited articles and highly burst articles in this research field has increased significantly since 2010. At present, this field is still in the development stage and has a broad research prospect. \mathrm{②} The United States, Australia, China and Germany have done plenty of researches on this issue and achieved a lot. At present, the number of research achievements supported by National Natural Science Foundation of China is in the lead over the world. \mathrm{③} Seawater intrusion, submarine groundwater discharge, the relationship between tide and hydrological conditions are the main research direction in this field. Hydrochemistry and isotopic analysis, and numerical simulation are the most important research methods in this field. \mathrm{④} The potential development directions and breakthroughs in this field include submarine groundwater discharge, the evolution of coastal mangrove wetlands, the migration and transformation of nutrients, the influences of different hydrological factors on coastal areas, and the impact of climate change on coastal areas. Overall, the future development of surface water and groundwater research in coastal areas is inseparable from the cross-integration of various disciplines, mutual verification of multiple methods and the introduction of new technical means.  相似文献