勉略构造带新元古代洋盆俯冲作用：来自略阳地区纸房沟岩片火山岩锆石U- Pb年龄和Lu- Hf同位素的证据     

徐通  张晓团  焦建刚  张红强  贾力 《地质学报》2020,94(12):3607-3624

纸房沟岩片位于勉略构造带略阳地区。通过细致的岩石学和地球化学研究，将纸房沟岩片内的火山岩分为拉斑玄武岩系列（Ⅰ类）和钙碱性火山岩系列（Ⅱ类）。Ⅰ类火山岩稀土配分曲线左倾，富Na贫P，整体具有N- MORB特点，形成于洋脊构造环境。相比Ⅰ类火山岩，Ⅱ类火山岩具有更高的SiO2(49.02％~61.86％)和K2O(0.32％~1.55％)含量，相对亏损Nb、Ta、P和Ti，形成于陆缘弧构造环境。Ⅱ类火山岩锆石Lu- Hf同位素测试结果显示，εHf(t)值主体为负值，介于-8.01~+0.77，表明其主要为古老地壳物质熔融成因。Ⅱ类火山岩LA- ICP- MS锆石U- Pb测年结果为854±3Ma(MSWD=0.12, n=30)、844±4Ma (MSWD=0.03, n=15)，表明纸房沟岩片火山岩结晶时代为新元古代早中期。综合前人成果认为，纸房沟岩片火山岩为新元古代勉略洋盆俯冲的产物，俯冲作用一直持续到800Ma左右，该俯冲过程很可能是对全球性Rodinia超大陆聚合事件的响应。  相似文献   

《东北地区1：150万大地构造相图》的编制     

刘英才  付俊彧  赵春荆  那福超  宋维民 《地质与资源》2020,29(1):1-6

东北地区1：150万大地构造相图是2018年出版的一份区域性大地构造图.该图依据不断积累和丰富的基础地质资料，将大地构造理论研究与综合应用汇总和集成，是东北地区科技创新成果和技术方法进步转化应用的重要体现.此次编图以板块构造理论和大陆动力学思维为指导，以多岛洋、弧-盆系发展演化观点为切入点，运用大地构造相分析方法，研究东北地区地壳形成、演化历史，以及大地构造环境及其与成矿作用的时空关系.较系统地阐述了东北地区的岩石构造组合、建造构造与构造演化阶段的宏观背景.  相似文献   

Gravity and magnetic field characteristics and regional ore prospecting of the Yili ancient continent,West Tianshan,Xinjiang Uygur Autonomous Region,China     

《China Geology》2020,3(1):104-112

Gold, iron, copper, lead-zinc and other mineral exploration in West Tianshan, Xinjiang Uygur Autonomous Region, has made remarkable progress in recent years. However, due to the dispute on the tectonic division of West Tianshan, the ore-controlling factors and the regional metallogenic laws are controversial. The authors analyze regional gravity data and notice that the high-value region corresponds to the Yili ancient continent, thus the southeastern boundary of the Yili ancient continent is delineated. Comparative analysis of gravity, aeromagnetic and geologic data reveals that the Tulasu basin, where some medium to large epithermal gold deposits locate, lies above the Yili ancient continent; the Yili Carboniferous-Permian rift extends in E-W direction, numbers of copper deposits have been found in the mid-west section of the rift which lies above the Yili ancient continent, whereas few copper deposits have been discovered in the east section which is outside the Yili ancient continent. Accordingly, the Yili ancient continent may he rich in gold, copper and other metal elements; the metal-bearing hydrothermal solution moves up with the activity of magmatism, and deposits in the favorable places (the Tulasu basin and the Yili Carboniferous-Permian rift), forming numerous small and medium gold, copper deposits, as well as some large and super-large gold deposits. Therefore, the tectonic-magmatic hydrothermal zone above the Yili ancient continent should be the prospective area for epithermal gold and copper polymetallic deposits.  相似文献   

Main progress and prospect for China's hydrogeological survey          下载免费PDF全文

WU Ai-min  HAO Ai-bing  GUO Hai-peng  LIU Jing-tao  ZHANG Er-yong  WANG Huang  WANG Xin-feng  WEN Xue-ru  ZHANG Cui-guang 《地下水科学与工程》2020,8(3):195-209

This paper reviewed the main achievements of hydrogeological survey in China, summarized the significant progress of hydrogeological survey over the past decade, and forecasted the key responsibilities for hydrogeological survey in the p14th Five-year Planq. The significant progress includes: China established the 1: 50 000 standard hydrogeological survey system with Chinese characteristics and produced the new generation of high-quality hydrogeological maps; the national groundwater monitoring project was completed and accepted, which marks China taking the leading position in groundwater monitoring internationally; fruitful results were achieved in the national groundwater quality survey, and groundwater quality background values were basically identified and checked; hydrogeological and environmental geological survey was continuously promoted in karst areas and the ecological restoration of rocky desertification achieved remarkable results; China strengthened layer exploration techniques for groundwater, integrating the key and practical techniques of layer exploration and monitoring; the exploration of groundwater in the poverty-stricken regions and old revolutionary base areas were effectively promoted to strongly guarantee the poverty alleviation and drinking water safety; the mystery of desert groundwater was uncovered, making up for the shortage of 1: 250 000 hydrogeological survey in the Badain Jaran Desert; and more efforts were made to conduct survey on the water resources in the basin, and to finish the unified measurement of national-scale groundwater level.  相似文献   

基于时间序列遥感数据的嵯岗国家沙化土地封禁保护成效评估     

田海静  孙涛  刘旭升  孔祥吉 《中国沙漠》2019,39(3):155-162

2013年中国启动实施了内蒙古自治区新巴尔虎左旗嵯岗国家沙化土地封禁保护区试点。本研究利用2001—2017年生长季NDVI数据分析了嵯岗封禁保护区及周边区域植被长势时空演变特征，分析了多年的生长季降水量和历年旱情，之后利用植被降水利用效率和NDVI残差趋势分析对保护成效进行了评估。结果表明：（1）封禁项目实施之前，封禁区内外植被长势变化趋势基本一致，而在项目实施后的2016、2017年，封禁区内NDVI距平明显高于封禁区外；（2）降水为影响该区域植被长势的主导气候因素，在封禁实施后的2015—2017年该区域连续3 a干旱，极大地限制了区域植被生长；（3）封禁区内植被降水利用效率和NDVI残差均呈现明显的增加趋势，而封禁区外变化不明显，说明封禁提升了植被的自我修复能力；（4）嵯岗封禁保护区由3个地块组成，其中嵯岗林场封禁效果比牧场八队和牧场十一队明显。国家沙化土地封禁保护措施有效促进了植被自我修复，提高了沙漠生态系统应对气候变化的能力。  相似文献   

Ancient deep roots for Mesozoic world-class gold deposits in the north China craton:An integrated genetic perspective     

Cheng-Xue Yang  M.Santosh 《地学前缘(英文版)》2020,11(1):203-214

The North China Craton(NCC)hosts some of the world-class gold deposits that formed more than 2 billion years after the major orogenic cycles and cratonization.The diverse models for the genesis of these deposits remain equivocal,and mostly focused on the craton margin examples,although synchronous deposits formed in the interior domains.Here we adopt an integrated geological and geophysical perspective to evaluate the possible factors that contributed to the formation of the major gold deposits in the NCC.In the Archean tectonic framework of the NCC,the locations of the major gold deposits fall within or adjacent to greenstone belts or the margins of micro-continents.In the Paleoproterozoic framework,they are markedly aligned along two major collisional sutures-the Trans North China Orogen and the Jiao-Liao-Ji Belt.Since the Mesozoic intrusions hosting these deposits do not carry adequate signals for the source of gold,we explore the deep roots based on available geophysical data.We show that the gold deposits are preferentially distributed above zones of uplifted MOHO and shallow LAB corresponding to thinned crust and eroded sub-lithospheric mantle,and that the mineralization is located above regions of high heat flow representing mantle upwelling.The NCC was at the center of a multi-convergent regime during the Mesozoic which intensely churned the mantle and significantly en riched it.The geophysical data on Moho and LAB upwarp from the centre towards east of the craton is more consistent with paleo-Pacific slab subduction from the east exerting the dominant control on lithospheric thinning.Based on these results,and together with an evaluation of the geochemical and isotopic features of the Mesozoic magmatic intrusions hosting the gold mineralization,we propose a genetic model that invokes reworking of ancient Au archives preserved in the lower crust and metasomatised upper mantle and which were generated through multiple subduction,underplating and cumulation events associated with cratonization of the NCC as well as the subduction-collision of Yangtze Craton with the NCC.The heat and material input along zones of heterogeneously thinned lithosphere from a rising turbulent mantle triggered by Mesozoic convergent margins surrounding the craton aided in reworking the deep roots of the ancient Au reservoirs,leading to the major gold metallogeny along craton margins as well as in the interior of the NCC.  相似文献   

淮南顾北矿F₁₀₄断层两侧岩溶水化学形成机制及导隔水性评价     

郑竹艳  许光泉  杨婷婷  余世滔  张海涛 《煤田地质与勘探》2020,48(1):129-137

利用断层两盘岩溶水化学特征判断其导隔水性对于我国华北型煤田水害防治具有十分重要的实践意义。以顾北矿F₁₀₄断层两侧太原组岩溶地下水为研究对象，在分析断层两盘水文地质条件基础上，采用Piper三线图、离子组合比和主成分法，分析了主要组分来源及水-岩作用差异性，并采用PHREEQC软件对岩溶地下水进行反向水化学模拟。结果表明:南北区岩溶水均存在方解石和白云石的溶解和沉淀现象，南区阳离子交换吸附和脱硫酸作用程度强于北区，而北区黄铁矿氧化和岩盐溶解作用较南区明显，南北两区水化学环境及水-岩作用存在显著差异，进而推断F₁₀₄断层具有较好的阻水性，且影响了其两侧的氧化-还原环境及温度差异，控制着地下水径流方向和水-岩作用程度。   相似文献   

黔南上司地区石炭系有孔虫:兼论华南维宪阶有孔虫生物地层序列     

沈阳  王训练  李玉坤  杨志华  岑武轩  王雪兵 《地学前缘》2020,27(6):213-233

石炭纪时期有孔虫具有演化快、分布广、数量丰富、分异度高的特点,对于地层的划分对比具有极为重要的意义。与全球其他重要的石炭纪沉积区相比,华南有孔虫生物地层划分精度相对较低。本文首次较为系统地报道了华南石炭系代表性岩石地层单位旧司组和上司组下部丰富的有孔虫化石及其在剖面上的分布情况,并综合现有关于华南的有孔虫化石资料,将华南维宪阶划分为7个有孔虫化石带,自下而上分别为Eoparastaffella simplex带、Viseidiscus/Planoarchaediscus带、Paraarchaediscus带、Pojarkovella nibelis带、Koskinotextularia带、Bradyina带和Janischewskina带。这些有孔虫带可与全球其他典型的石炭纪沉积区进行很好的对比,从而为相关的研究提供一个较为精细的地层格架。通过对黔南上司地区有孔虫的研究,提议中国石炭系区域性年代地层单位上司阶底界可用有孔虫Bradyina的首现定义,并将上司阶与西欧的Warnantian亚阶中上部和俄罗斯的Aleksinian亚阶—Venevian亚阶对比,对应国际维宪阶上部,为全球石炭系年代地层对比提供了可靠的化石依据。  相似文献   

GPM和TRMM卫星日降水数据在黄河源区的适用性分析     

刘兆晨  杨梅学  王学佳  程立真 《冰川冻土》2020,42(2):575-586

通过评估GPM计划三种日降水产品（IMERG-E、 IMERG-L和IMERG-F）和TRMM卫星、 两种日降水产品（TMPA 3B42和TMPA 3B42RT）在黄河源及其周边区域38个台站的适用性， 探究了五种产品探测精度和海拔高度及雨强的相关关系， 结果表明： 在与实测资料的一致性和偏差方面， GPM卫星产品要全面优于TMPA产品。在TRMM卫星产品中， 3B42产品明显优于3B42RT。五种产品的相关系数均表现出明显的从东南到西北递减的趋势， 均方根误差北部普遍低于南部。IMERG产品的探测率（POD）和探测成功率（CSI）都要普遍高于TMPA产品， 而误报率（FAR）则是TMPA 产品更低， 表现更好。五种产品均在个别台站出现了严重误报的情况， 这些台站主要分布在研究区的西北部。IMERG三种产品对于海拔高度的依赖程度具有很强的一致性， 而3B42RT产品对海拔高度几乎没有依赖。除3B42RT产品外， 其余四种产品的偏差均随雨强的增加而增大。在探测率方面， IMERG产品对小雨、 中雨和大雨的探测能力均优于TMPA产品。  相似文献   

2010-2018年北极夏季中国北极科学考察航行期间被动微波遥感海冰密集度与船基目视观测资料的比较   总被引：2，自引：0，他引：2  

修苑人  李志军  雷瑞波  王庆凯  卢鹏  Lepp&#;ranta Matti 《海洋学报(英文版)》2020,39(9):38-49

为了更有效地将卫星数据应用于北极航行导航，被动微波（PM）产品的海冰密集度（SIC）与从中国北极科学考察中收集到的船基目视观测（OBS）资料进行了比较。在2010、2012、2014、2016和2018年的北极夏季总共收集了3667组目测数据。PM SIC取自基于SSMIS传感器的NASA-Team（NT）、Bootstrap（BT）以及Climate Data Record（CDR）算法和基于AMSR-E/AMSR-2传感器的BT、enhanced NT（NT2）以及ARTIST Sea Ice（ASI）算法。使用PM SIC的日算术平均值和OBS SIC的日加权平均值进行比较。比较了PM SIC和OBS SIC之间的相关系数，偏差和均方根偏差，包括总体趋势以及在轻度/普通/严重冰况下的情况。使用OBS数据，浮冰尺寸和冰厚对不同PM产品SIC反演的影响可以通过计算浮冰尺寸编码和冰厚的日加权平均值来评估。我们的结果显示相关系数的范围为0.89（AMSR-E/AMSR-2 NT2）到0.95（SSMIS NT），偏差的范围为-3.96%（SSMIS NT）到12.05%（AMSR-E/AMSR-2），均方根偏差的范围为10.81%（SSMIS NT）到20.15%（AMSR-E/AMSR-2 NT2）。浮冰尺寸对PM产品的SIC反演有显著的影响，大多数PM产品倾向于在小浮冰尺寸情况下低估SIC，而在大浮冰尺寸情况下高估SIC。超过30 cm的冰厚对于PM产品的SIC反演没有明显影响。总体来看，在北极夏季，SSMIS NT SIC与OBS SIC之间有着最好的一致性，而AMSR-E/AMSR-2 NT2 SIC与OBS SIC的一致性最差。  相似文献