Genesis of S-type Granites in the Pengshan Sn-polymetallic Ore Field, Northern Jiangxi Province and its Implications     

YIN Qingqing  XIANG Xinkui  YU Zhendong  YANG Xiufeng  WANG Tianchen  ZHONG Bo  TAN Rong  LIAO Jianhai  ZHU Yuansong 《《地质学报》英文版》2020,94(6):1860-1873

The Pengshan Sn-polymetallic ore field is located in the southeastern part of the Yangtze block, spanning the southeast edge of the MLYDZ and the northern edge of the mid-segment of the Jiangnan Uplift, and on one side of the MLYDZ. The studies of LA–ICP–MS zircon U–Pb chronology and petrogeochemistry for Early Cretaceous acid granites from the Pengshan ore field were carried out in this paper. We report zircon U–Pb geochronology and whole-rock geochemistry for acid granites in the Pengshan ore field. The zircon U–Pb ages of the muscovite-granite, biotite adamellite and granite-porphyry are 127.6 ± 1.7 Ma, 126.9 ± 1.6 Ma and 126.6 ± 2.0 Ma, respectively. The granites in Pengshan are characterized by a high silicon content and are rich in alkali. They belong to high-potassium, calc-alkaline, peraluminous granite. The rocks have a relatively high Rb/Ba ratio, and the data points for muscovite-granite and biotite adamellite all fall within the clay-rich sources region, near the pelite-derived end-member, showing that the Pengshan muscovite-granite and biotite adamellite mainly originated from the partial melting of metapelites with high maturity. The transformation of the compressional and extensional tectonics in this region approximately 128 Ma obviously lags behind that in the mid-segment of the Jiangnan Uplift (135 Ma), but occurred earlier than the MLYDZ (126 Ma). The Pengshan ore field extends from the mid-segment of the Jiangnan Uplift to the MLYDZ. Although the tectonic stress field is constrained by the combination of the two secondary tectonic units, the time of tectonic system transformation is closer to the MLYDZ because the spatial orientation of the area is enclosed in the MLYDZ. Relevant geophysical and drilling data confirm the rationality of Pengshan–Ao’xia as a multi-center vertical zoning ore field, and show the scientificity of the prospecting idea of abutting joint between the north-west of Pengshan area and the south-east of Ao’xia area.  相似文献   

Conversion relationship of rainfall-soil moisture-groundwater in Quaternary thick cohesive soil in Jianghan Plain,Hubei Province,China     

《China Geology》2020,3(3):462-472

The scientific field test site of rainfall-soil moisture-groundwater conversion in Dabie Mountain Area–Jianghan Plain is located in the northern region of the Jianghan Plain, the transition zone between the Dabie Mountain Area and Jianghan Plain. It’s a great field test site to study the material and energy exchange among rainfall, soil moisture, and groundwater of the Earth ’s critical zone in subtropical monsoon climate plain areas. This paper analyzed the connection between rainfall and volume water content (VWC) of soil at different depths of several soil profiles, and the dynamic feature of groundwater was discussed, which reveals the rainfall infiltration recharge of Quaternary Upper Pleistocene strata. The results show that the Quaternary Upper Pleistocene aquifer groundwater accepts a little direct rainfall recharge, while the lateral recharge is the main supplement source. There were 75 effective rainfall events among 120 rainfall events during the monitoring period, with an accumulated amount of 672.9 mm, and the percentages of effective rainfall amount and duration time were 62.50% and 91.56%, respectively. The max evaporation depth at the upper part in Quaternary cohesive soil was no less than 1.4 m. The soil profile was divided into four zones: (1) The sensitive zone of rainfall infiltration within 1.4 m, where the material and energy exchange frequently near the interface between atmosphere and soil; (2) the buffer zone of rainfall infiltration between 1.4 m and 3.5 m; (3) the migration zone of rainfall infiltration between 3.5 m and 5.0 m; and (4) the rainfall infiltration and groundwater level co-influenced zone below 5.0 m. The results revealed the reaction of soil moisture and groundwater to rainfall in the area covered by cohesive soil under humid climate in Earth ’s critical zone, which is of great theoretical and practical significance for groundwater resources evaluation and development, groundwater environmental protection, ecological environmental improvement, drought disaster prevention, and flood disaster prevention in subtropical monsoon climate plain areas.  相似文献   

不同顶管组合方式的管幕冻结温度场模型试验   总被引：1，自引：1，他引：0  

段寅  荣传新  程桦  蔡海兵  解德柱  丁杨龙 《冰川冻土》2020,42(2):479-490

拱北隧道作为港珠澳大桥珠海连接线的关键性工程， 在国内外首次成功运用了管幕冻结技术。以此为背景， 为更加全面地掌握饱和软土地层中管幕冻结温度场的分布特点， 开展了不同顶管组合方式下的管幕冻结温度场模型试验研究。试验结果表明： 各测点温度曲线在积极冻结期前4 h急剧下降， 随后逐渐减缓， 降至砂土冰点后趋于平稳， 三种布管方式均满足冻结设计要求； 冻结管中低温盐水提供的冷量首先传递给顶管管壁， 再以“面”的形式均匀地传递给周围土体； 积极冻结21 h后， 采用四根空顶管组合的C区冻结壁竖向范围最大， 空管管壁正上方冻结壁平均厚度约为105 mm， 在满足管幕刚度设计要求的前提下， 可采此布管方式以达到快速形成冻结帷幕的目的。限位管开启后的4 h内， 实顶管中线垂直距离100 mm范围内测点温度曲线虽有明显回升但仍维持在冻土冰点以下， 超出此范围后温度变化影响逐渐减弱， 且顶管间冻结壁稳定存在， 表明限位管在满足管间有效封水的条件下， 能在一定范围内起到定向限制地层冻胀的作用。优化后的双圆形冻结管在满足冻结设计要求的同时， 更加便于安装且经济环保。  相似文献   

大孔隙对径流过程影响的研究进展          下载免费PDF全文

吕海深 《水文》2020,40(1):13-17

大孔隙流是土壤优先流的一种,在植被发育区土壤大孔隙比较常见,对径流形成过程产生重要的影响。介绍了大孔隙流的研究方法,系统总结了近50年植被发育区土壤大孔隙对降雨入渗过程及径流形成过程的影响:从水分入渗的角度,大孔隙可以加快降雨入渗过程;由土壤大孔隙流与山坡产流的关系,大孔隙促进了边坡雨水的运动进而引起了快速产流;世界范围内的研究都表明土壤管流或大孔隙流是径流组分重要贡献者。  相似文献   

东海盆地中、新生代盆架结构与构造演化   总被引：6，自引：0，他引：6  

刘金水  许怀智  蒋一鸣  王军  何新建 《地质学报》2020,94(3):675-691

基于地貌、钻井、岩石测年和地震等资料,分析盆地地层分布、盆架结构、构造单元划分和裂陷迁移规律,结果表明东海盆地由台北坳陷、舟山隆起、浙东坳陷、钓鱼岛隆褶带和冲绳坳陷构成,是以新生代沉积为主、中生代沉积为辅的大型中、新生代叠合含油气盆地;古元古代变质岩系构成了盆地的基底。该盆地不仅是印度-太平洋前后相继的动力体系作用下形成的西太平洋沟-弧-盆构造体系域一部分,而且也是古亚洲洋动力体系作用下形成的古亚洲洋构造域和特提斯洋动力体系作用下形成的特提斯洋构造域一部分,晚侏罗世至早白垩世经历了构造体制转换,盆地格局发生重大变革,早白垩世以前主要受古亚洲-特提斯洋构造体制影响的强烈挤压造山和地壳增厚作用演变为早白垩世以来主要受太平洋构造体制控制的陆缘伸展裂陷和岩石圈减薄作用,经历侏罗纪古亚洲-特提斯构造体制大陆边缘拗陷和白垩纪以来太平洋构造体制弧后裂陷两大演化阶段。白垩纪以来太平洋构造体制的弧后裂陷演化阶段可细分为早白垩世至始新世裂陷期、渐新世至晚中新世拗陷期和中新世末至全新世裂陷期。  相似文献   

北天山中段时变重力场离散小波多尺度分解     

陈丽  艾力夏提·玉山  朱治国  李瑞 《中国地震》2020,36(4):935-944

利用北天山地区2016～2019年观测的4期流动重力观测资料，分析研究一年尺度的重力场动态变化特征，并利用小波分析方法，将不同场源深度的重力异常进行分离。通过功率谱分析，获取各阶小波重力细节对应的场源深度。研究结果表明，2017年8月9日精河M_S6.6地震前，震中位于负值集中区，四阶小波重力细节显示震中附近出现明显的四象限分布；2020年1月16日库车M_S5.6地震前，震中位于负值区，小波重力细节整体量值较小；功率谱估算的场源近似深度与2次地震的震源深度相近。  相似文献   

Study on multiple induced polarization parameters in groundwater exploration in Bashang poverty alleviation area of Heibei Province,China          下载免费PDF全文

LIU Zhi-yuan  TAN Ding  CHEN Zhi-bin  WEI Yun-fei  CHAI Quan  CHEN Xiao-hang 《地下水科学与工程》2020,8(3):274-280

The study examines a water exploration and poverty alleviation project in Guyuan county. The study analyzes correlations between aquifers and multiple induced polarization (IP) parameters, including resistivity, polarizability, deviation, half decay time, water-bearing factors, and Kc, a new parameter refined in this study. Based on the study, the well was placed accurately, and its maximum water inflow reached 30 m³/h. Kc value highlights the rate of change at early stages of IP secondary field. Kc value served as a quick indicator in this groundwater prospecting and is validated in practice. Progress has been made in finding new parameters in exploring water with IP method. Thanks to the project, local people have access to water and poverty alleviation has scored some achievements.  相似文献   

2017-08-09新疆精河Ms6.6地震附近区域相对应变的变化分析     

高丽娟  邢喜民  高歌  李尚伟 《大地测量与地球动力学》2019,39(10):1002-1006

2017年精河M_S6.6地震震前，尼勒克、巴伦台和小泉沟台钻孔应变仪记录到显著的应变变化，经现场落实确认，异常是可靠的。根据这3个台的记录资料计算相对应变的变化，结果表明，地震前最大（小）主应变大小和方向分别出现明显加速和急剧偏转变化。此外还发现，相对应变场异常期间主方向与震源机制解P轴方位较为一致。  相似文献   

闽中南平—宁化构造带南华纪陆缘弧岩浆活动：对武夷造山带构造演化的新启示     

姜杨  赵希林  李龙明  潘桂棠  徐敏成  黄文成  刘欢 《中国地质》2020,47(4):1010-1024

南平—宁化构造带沿线出露着以万全岩群和楼前组、西溪组等为代表的一系列新元古代火山-沉积岩系。系统的岩石学、年代学和地球化学研究表明,福建明溪和江西瑞金地区的楼前组浅变质英安岩和晶屑凝灰岩分别形成于(729±4)Ma和(735±6.7)Ma(LA-ICP-MS锆石U-Pb法),SiO2含量变化在65.22%～74.54%,相对富Al2O3(11.05%～16.80%)富碱(Na2O+K2O=4.88%～10.19%)而贫CaO、MgO和FeOT,ANK值和A/CNK值分别为1.23～1.78和0.98～1.57,Nb/Ta=12.44～17.28,Nd/Th=2.07～3.51,Ti/Zr=6.08～10.37,Ti/Y=68.51～154.71,属过铝质S型火山岩;明显富集大离子亲石元素(Ba、Rb等)而亏损高场强元素(Nb、Ta、Ti、P等),Zr/Nb=16.65～24.07,Th/Ta=12.94～16.93,δEu呈现明显负异常(0.33～0.62),显示岛弧岩浆岩的地球化学特征。综合区域地质资料及前人研究结果提出,南平—宁化一线在713 Ma前为活动大陆边缘环境,洋壳俯冲引发的岩浆活动形成了沿南平—宁化—瑞金一线展布的陆缘弧中酸性火山岩带,暗示此时南、北武夷之间尚未拼合形成统一的武夷地块,因而华夏地块不存在统一的前南华纪结晶基底。  相似文献   

渭河盆地地温场分布规律及其控制因素     

任战利  刘润川  任文波  祁凯  杨桂林  崔军平  杨鹏  张园园 《地质学报》2020,94(7):1938-1949

本文以渭河盆地地温场为研究对象,在收集补充新地热井资料及分析测试样品的基础上,通过盆地深部结构、构造特征、地温场特征、热储层特征、地热资源量等分析,建立了盆地不同岩性岩石热导率与深度关系图版,确定了盆地地温场变化规律及地热田控制因素,提出了渭河盆地地热田形成模式。评价了盆地地热资源有利区,为盆地后续的开发利用提供了理论支持。研究认为渭河盆地热地温梯度分布在2.34～5.85℃/100m之间,平均地温梯度为3.50℃/100m,代表性大地热流68.33mw/m~2,地温梯度及不同深度地层温度具有东高西低、南高北低的特点。热导率总体上具有随深度的增加,逐渐增大的规律,热导率随深度增加主要受压实程度增强控制。相同深度条件下泥岩热导率最低,砂岩热导率居中、白云岩热导率最高。渭河盆地主要为层状地热田,盆地内地热通过热传导及热对流两种方式进行传递,以热传导为主。渭河盆地地热资源丰富,热储层可分为三种类型:①新生界砂岩孔隙型;②下古生界碳酸盐岩岩溶型;③断裂型。渭河盆地地热资源有利区主要分布于西安凹陷、固市凹陷。盆地地温场及地热田分布与莫霍面、软流圈上隆、岩石圈厚度减薄的深部背景密切相关,主要受地热传导和深大断裂热对流控制,是岩石圈深部结构、盆地构造、基底岩性、储盖组合等多因素共同作用下形成的。最后结合当前渭河盆地地热资源开发利用现状及存在问题,提出了地热开发利用建议。  相似文献