东昆仑祁漫塔格小圆山地区辉长辉绿岩年龄、地球化学特征及对区域构造演化的约束

通过东昆仑祁漫塔格小圆山辉长辉绿岩岩相学、年代学和岩石地球化学研究, 探讨其岩浆作用及其源区、成岩构造环境、年龄及地质意义。结果表明, 辉长辉绿岩为拉斑玄武岩系列岩石, SiO2含量为48.27%~50.06%, 全碱Na2O+K2O含量低, 为3.10%~4.04%, 且钠较钾富, MgO含量为7.81%~8.60%, TFe2O3含量为10.69%~12.00%, TiO2含量为1.32%~1.76%;∑REE平均为58.13×10-6, δEu值为1.02~1.24, 平均为1.12, 呈轻微正异常; 稀土元素球粒陨石标准化配分模式图上呈Gd略亏损的近平坦曲线, 具有轻、重稀土元素分异不明显的轻稀土元素弱富集特征; 岩石明显富集大离子亲石元素Cs、Rb、Ba、K、Sr, 活泼的不相容元素U和Th, 轻稀土元素及Pb, 相对亏损高场强元素Nb、Ta和P。采用SIMS锆石U-Pb定年方法, 获得小圆山辉长辉绿岩的年龄加权平均值为415±16 Ma (MSWD=5.0)和243±11 Ma (MSWD=4.1), 前者代表辉长辉绿岩的结晶年龄, 后者应代表晚期深部岩浆上升侵位到辉长辉绿岩中形成的锆石结晶年龄, 是对中三叠世末期伸展活动的响应。结合岩石地球化学、构造特征和区域地质背景, 认为小圆山辉长辉绿岩是拉张型岛弧背景下亏损的岩石圈地幔平衡部分熔融的产物, 受到一定程度地壳物质的混染。     

Sequence Stratigraphy of the Jurassic Coal Measures in Northwestern China

The sequence stratigraphy of the Jurassic coal measures of northwestern China has been studied based on data from outcrop and borehole sections. Because of the geological background and the diversity of basin types, such as isochronisms of coal seams and recognition of key sequence boundaries, it is rare to summarize and correlate sequence structure and framework. The types and recognition characteristics of the sequence boundaries of the Jurassic coal measures are revealed by comparing climatic characteristics, structural styles and the base level cycle. A total of five third-order sequences and 15 systems tracts have been subdivided and the sequence stratigraphic framework has been reconstructed confirming that the thick coals accumulated in the late stage of transgression system tracts of sequence I (SQ I) and sequence III (SQ III). This idea is of important academic significance for instructing coal resources exploration, and enhancing geological effects of prospecting engineering. It is also of practical significance for guaranteeing construction of the large-scale coal production base in northwestern China, accelerating the westward development of the coal industry stratagem.     

江西东坪石英脉型黑钨矿矿床地质特征、控矿因素及找矿标志

东坪钨矿床是近年在赣北地区新发现的首个超大型石英脉型黑钨矿矿床,位于长江中下游成矿带幕阜山地区东坪-香炉山钨矿找矿远景区东部。矿床赋矿层位为新元古代双桥山群安乐林组浅变质岩系,北东向断裂及其两侧的次级裂隙为区内主要控矿构造、容矿构造,隐伏的燕山晚期黑云母二长花岗岩为成矿岩体,与区内钨多金属成矿关系密切的为石英脉状硅化;两个矿带的钨矿体均产于成矿岩体外接触带,呈现了石英脉型黑钨矿矿床典型的"五层楼"分带特征,矿石工业类型主要为黑钨矿矿石;明确了构造和岩浆岩等主要控矿因素;总结出地表微细裂隙云英岩化-黄铁矿化蚀变带、含硫化物石英细脉带、石英脉、重砂及地球化学异常为区内主要找矿标志。     

福建黄塘晚侏罗世长林组硅质岩地球化学特征及其沉积环境意义

福建黄塘地区晚侏罗世长林组发育一套层状硅质岩,夹薄层凝灰岩,产硅质海绵骨针和硅质钙藻,其硅质岩沉积环境复杂,成因一直存在不同认识。本文通过野外地质调查和岩相学研究,以及主量元素、稀土元素和微量元素分析认为,该区硅质岩为非纯硅质岩,在FeMnAl三角图中样品位于生物成因区及附近,Mo和V含量富集、轻稀土富集、Eu弱负异常及U/Th值也都具有典型的生物成因特征,且微观特征显示其受到火山活动的影响。黄塘硅质岩在Fe2O3/TiO2Al2O3/(Al2O3+Fe2O3)、TFe2O3/(100-SiO2)Al2O3/(100-SiO2)和(La/Ce)NAl2O3/(Al2O3+Fe2O3)图解中都投在了大陆边缘及附近。ΣREE值较高、Ceanom值、MnO/TiO2值及(La/Yb)N值等这些地球化学指标一致表明黄塘硅质岩处于受陆源物质影响的大陆边缘浅海沉积环境。在前人研究基础上,认为研究区在晚侏罗世早期开始发生海侵并伴有小规模的火山活动,整体为还原环境,局部可能水体较深,为进一步开展福建、浙江地区的石油地质评价工作提供了依据。     

四川冕宁缅萨洼金矿地质特征及成因浅析

矿区位于康滇台隆与盐源一丽江台缘坳陷分界断裂带上。主要控矿构造为S-N向断裂带;矿(化)体形态、产状严格受糜棱岩化控制;主要矿石类型有“石英脉型”和“蚀变岩型”两类硫化物金矿石。成矿物质主要来源于绿片岩,矿化与韧性剪切带密切相关。     

浅析长沙市地质灾害发育特征及防治对策

长沙市是湖南省地质灾害的多发区之一。地质灾害不仅造成生命财产的巨大损失,而且对当地的投资环境乃至社会的持续发展都构成严重威胁。在介绍了长沙市的区域自然地理与地质环境,阐述了研究区内的滑坡、崩塌、不稳定斜坡、地面塌陷、泥石流等地质灾害的发育特征和形成条件的基础上,全面分析研究地质灾害的发展趋势,并结合当地经济条件与地质灾害现状,给出了较为切实可行的地质灾害防治对策,为长沙市的防灾、减灾和促进区域经济社会可持续发展提供科学依据。     

内蒙古元宝山小建昌营子地区三面井组沉积环境

在进行内蒙古1∶5万区域地质调查工作中,对内蒙古赤峰元宝山镇小建昌营子一带的下二叠统三面井组砂岩进行了粒度分析。结果表明,萨胡成因环境判别值为10.66~10.76,沉积环境为河流相或三角洲相;弗里德曼粒度参数判别为陆相河砂沉积;浊流C-M判别图解显示沉积环境介于三角洲与浊流沉积之间。三面井组总体为一套河流相-三角洲前缘滑塌浊积扇沉积。滑塌浊积扇一般发育于深湖、半深湖区,结合本地区三面井组地层中缺乏海相碳酸盐岩沉积,综合认为本区的三面井组形成于河流-湖泊三角洲环境。     

西沱变形体特征及稳定性评价

在阐述西沱变形体基本特征的基础上,研究分析变形体变形的主要影响因素——地质环境因素(地形地貌、地层岩性、物质结构)、外界影响因素(降水因素、洪水因素、人为因素、新构造及地震),以及变形体近期变形特征,通过剖面递推系数法计算,对变形体的稳定性进行了评价,为变形体优化整治措施提供依据。     

晋城矿区东部9#煤聚煤期沉积环境演化

研究区位于山西沁水煤田东南部，晋城矿区的东部边缘，面积96km^2.该区普遍发育石炭、二叠纪地层。区内有晋城煤业集团古书院、王台铺、凤凰山三对生产矿井。以勘探资料为基础，对该区9号煤层赋存规律、成煤古地理及其演化进行了分析研究，阐述了沉积环境对煤层厚度的控制作用。     

Palynostratigraphy and palynofacies indications of depositional environments and source potential for hydrocarbons: the mid Cretaceous Nahr Umr and lower Mauddud formations, Iraq

Palynomorphs recovered from core and cuttings samples from five boreholes in the East Baghdad Oilfield indicate a mid Albian–early Cenomanian age-range for the Nahr Umr Formation and the lower part of the overlying Mauddud Formation. Two palynomorph zones and four types of palynofacies have been identified. The latter are interpreted to indicate delta-top swamp and marsh, silty–muddy deltaic, inner silty and carbonate-rich platform, and limestone-platform environments. The palynofacies of the two types of platform accumulations suggest that these are potential sources of biogenic methane and condensates, and may yield more liquid hydrocarbons in areas where the formations are at greater depths than within the region studied.