福贡地区石炭系地层可能属于拉萨地块:来自碎屑锆石年龄谱的指示   总被引：1，自引：1，他引：0  

信迪  杨天南  薛传东  廖程  韩雪  梁明娟  李晓天 《岩石学报》2018,34(5):1335-1346

欧亚与印度大陆的碰撞使得印度大陆的北东角强烈挤入欧亚大陆内部,形成东构造结,其引发的强烈变形将南羌塘地块、北羌塘地块、拉萨地块、保山地块、兰坪-思茅地块以及地块之间的缝合带挤压于很窄的范围内,造成青藏高原腹地与其东南缘之间构造单元划分、对比困难。滇西福贡地区位于青藏高原东南缘,东构造结影响范围内,是三江造山带及青藏高原相关地块的汇聚处。福贡地区石炭系岩石组合表明其形成于较为稳定的浅海相沉积环境中,具有被动大陆边缘沉积特征。三件石炭系二云母石英片岩碎屑锆石表面年龄数据(194个有效分析点)形成五个主要年龄区间:2550~2400Ma、1800~1550Ma、1200~1080Ma、1000~850Ma和600~480Ma,峰值分别为~2502Ma、~1724Ma、~1120Ma、~886Ma和~512Ma。对比其他地块同时代地层的碎屑锆石年龄谱表明,福贡地区石炭系可能是拉萨地块的一部分,与腾冲地块一样,属于其南延部分。结合中新生代岩浆岩带的构造连续性,我们认为,印度板块东北角向北、北东方向的强烈挤压导致拉萨地块及冈底斯岩浆岩带弯曲、缩颈、并发生分离与旋转。  相似文献   

Development Phases and Mechanisms of Tectonic Fractures in the Longmaxi Formation Shale of the Dingshan Area in Southeast Sichuan Basin, China     

FAN Cunhui  HE Shun  ZHANG Yu  QIN Qirong  ZHONG Cheng 《《地质学报》英文版》2018,92(6):2351-2366

Shale gas has currently attracted much attention during oil and gas exploration and development. Fractures in shale have an important influence on the enrichment and preservation of shale gas. This work studied the developmental period and formation mechanism of tectonic fractures in the Longmaxi Formation shale in the Dingshan area of ??southeastern Sichuan Basin based on extensive observations of outcrops and cores, rock acoustic emission (Kaiser) experiments, homogenization temperature of fracture fill inclusions, apatite fission track, thermal burial history. The research shows that the fracture types of the Longmaxi Formation include tectonic fractures, diagenetic fractures and horizontal slip fractures. The main types are tectonic high-angle shear and horizontal slip fractures, with small openings, large spacing, low densities, and high degrees of filling. Six dominant directions of the fractures after correction by plane included NWW, nearly SN, NNW, NEE, nearly EW and NW. The analysis of field fracture stage and fracture system of the borehole suggests that the fractures in the Longmaxi Formation could be paired with two sets of plane X-shaped conjugate shear fractures, i.e., profile X-shaped conjugate shear fractures and extension fractures. The combination of qualitative geological analysis and quantitative experimental testing techniques indicates that the tectonic fractures in the Longmaxi Formation have undergone three periods of tectonic movement, namely mid-late Yanshanian movement (82–71.1 Ma), late Yanshanian and middle Himalaya movements (71.1–22.3 Ma), and the late Himalayan movement (22.3–0 Ma). The middle-late period of the Yanshanian movement and end of the Yanshanian movement-middle period of the Himalayan movement were the main fracture-forming periods. The fractures were mostly filled with minerals, such as calcite and siliceous. The homogenization temperature of fracture fill inclusions was high, and the paleo-stress value was large; the tectonic movement from the late to present period was mainly a slight transformation and superposition of existing fractures and tectonic systems. Based on the principle of tectonic analysis and theory of geomechanics, we clarified the mechanism of the fractures in the Longmaxi Formation, and established the genetic model of the Longmaxi Formation. The research on the qualitative and quantitative techniques of the fracture-phase study could be effectively used to analyze the causes of the marine shale gas fractures in the Sichuan Basin. The research findings and results provide important references and technical support for further exploration and development of marine shale gas in South China.  相似文献   

容县压实花岗岩残积土的力学性质与微结构特性研究     

王志兵  麦棠坤  齐程 《水文地质工程地质》2018,(5):101-101

选取广西容县花岗岩残积土为研究对象,取击实曲线上3个不同含水率对应的压实样（最佳含水率及干侧、湿侧,后两者对应的干密度相同）分别进行了直剪试验、扫描电镜观测（SEM）和压汞试验（MIP）,并从微观特征解释其力学性能的差异。结果表明:（1）花岗岩残积土在3种压实状态下具有相同应力-应变曲线形状,无明显峰值,抗剪强度在最佳状态时的最高,湿侧状态抗剪强度与干侧状态相近,3种状态下内摩擦角值差别较小,但黏聚力在最佳状态时最大,干侧和湿侧状态较最佳状态分别下降66.4%和43.1%;（2）花岗岩残积土在湿侧状态下普遍形成团聚体,团聚体之间呈架空结构,累积孔隙体积最大,为明显的双峰分布孔隙特征;在最佳状态下组构最密,高岭石片定向性排列;在干侧状态下高岭石片呈片架结构,累积孔隙体积最小;随着含水率的降低,土样双峰孔隙特征逐渐变得不明显;（3）花岗岩残积土在不同状态时的微观特性较好地解释其力学性质的差异。  相似文献   

贵州省都匀市滑坡易发性评价研究   总被引：6，自引：1，他引：5  

任敬  范宣梅  赵程  周礼  窦向阳 《水文地质工程地质》2018,(5):165-165

都匀市是贵州省城镇滑坡地质灾害多发频发区。文章以都匀市沙包堡镇为研究区,采用栅格单元提取高程、坡度、岩性、水系等9项致灾因子,分别使用都基于数学统计模型的定量分析方法（二元逻辑回归模型、信息量模型）和定性分析方法（层次分析模型）对都匀市研究区滑坡地质灾害易发性进行评价。结果表明:二元逻辑回归模型预测精度与预测效果均为最优,其ROC曲线下面积AUC值为0.873,易发性分区中高易发区和中易发区内预测发生滑坡面积比占95.41%,且最符合野外实地调查验证情况。评价方法与结果可为贵州城镇地区滑坡地质灾害评价和防治提供借鉴。  相似文献   

Elemental characteristics and paleoenvironment reconstruction: a case study of the Triassic lacustrine Zhangjiatan oil shale,southern Ordos Basin,China     

Delu Li  Rongxi Li  Zengwu Zhu  Xiaoli Wu  Futian Liu  Bangsheng Zhao  Jinghua Cheng  Baoping Wang 《中国地球化学学报》2018,37(1):134-150

Using trace elements to reconstruct paleoenvironment is a current hot topic in geochemistry. Through analytical tests of oil yield, ash yield, calorific value, total sulfur, major elements, trace elements, and X-ray diffraction, the quality, mineral content, occurrence mode of elements, and paleoenvironment of the Zhangjiatan oil shale of the Triassic Yanchang Formation in the southern Ordos Basin were studied. The analyses revealed relatively high oil yield (average 6.63%) and medium quality. The mineral content in the oil shale was mainly clay minerals, quartz, feldspar, and pyrite; an illite–smectite mixed layer comprised the major proportion of clay minerals. Compared with marine oil shale in China, the Zhangjiatan oil shale had higher contents of quartz, feldspar, and clay minerals, and lower calcite content. Silica was mainly in quartz and Fe was associated with organic matter, which is different from marine oil shale. The form of calcium varied. Cluster analyses indicated that Fe, Cu, U, V, Zn, As, Cs, Cd, Mo, Ga, Pb, Co, Ni, Cr, Sc, P, and Mn are associated with organic matter while Ca, Na, Sr, Ba, Si, Zr, K, Al, B, Mg, and Ti are mostly terrigenous. Sr/Cu, Ba/Al, V/(V + Ni), U/Th, AU, and δU of oil shale samples suggest the paleoclimate was warm and humid, paleoproductivity of the lake was relatively high during deposition of the shale—which mainly occurred in fresh water—and the paleo-redox condition was dominated by reducing conditions. Fe/Ti ratios of the oil shale samples suggest clear hydrothermal influence in the eastern portion of the study area and less conspicuous hydrothermal influence in the western portion.  相似文献   

Distribution and geochemical significance of trace elements in shale rocks and their residual kerogens     

Jian-bing Xu  Bin Cheng  Qian Deng  Yun-gan Liang  Oluwabamise Lekan Faboya  Ze-wen Liao 《中国地球化学学报》2018,37(6):886-900

There is a dearth of information about the distribution of trace elements in kerogen from shale rocks despite several reports on trace element composition in many shale samples. In this study, trace elements in shale rocks and their residual kerogens were determined by inductively coupled plasma–mass spectrometry. The results from this study show redox-sensitive elements relatively concentrated in the kerogens as compared to the shales. This may be primarily due to the adsorption and complexation ability of kerogen, which enables enrichment in Ni, Co, Cu, and Zn. For the rare earth elements (REEs), distinct distribution characteristics were observed for shales dominated by terrigenous minerals and their kerogen counterparts. However, shales with less input of terrigenous minerals showed similar REE distribution patterns to their residual kerogen. It is speculated that the distribution patterns of the REEs in shales and kerogens may be source-related.  相似文献   

岸滩侧蚀崩塌速率的试验量测方法          下载免费PDF全文

假冬冬  陈诚  牛晨曦  张幸农 《水科学进展》2018,29(4):537-542

岸滩侧蚀崩塌现象普遍存在于冲积河流演变过程中,是河道治理需重点关注的问题之一,岸滩侧蚀崩塌速率的准确量测则是崩岸机理及其治理措施研究的关键基础。基于图像处理技术,建立了河岸侧蚀崩塌速率试验量测系统,通过图像追踪河岸模型上边缘示踪网格位置变迁,提出了一种河岸侧蚀崩塌速率测量方法。以试验水槽为例,对河岸侧蚀崩塌速率进行了量测,并与经验公式计算值进行了比对,两者基本吻合,可较好地反映流速、土体级配等岸滩侧蚀崩塌速率的影响因素及其变化规律。研究成果可为江河崩岸机理的深入研究提供技术支撑。  相似文献   

重度石漠化区不同土地利用方式下土壤养分特征   总被引：1，自引：1，他引：0  

朱梓弘  杨程  谢银财  王群  朱同彬 《中国岩溶》2018,37(6):842-849

本文以云南省蒙自市西北勒乡碧色寨村石漠化土地为研究对象,基于主成分分析法（PCA）研究岩溶石漠化区不同土地利用方式下的土壤养分特征。结果表明:（1）研究区土壤各养分指标变异系数介于0.14~1.76,不同土地利用方式下,土壤养分状况有较大差异;（2）研究区土壤12项养分指标可归结为3个主成分,所提供的信息占全部信息的90.69%,其中PC1主要包含了全磷、有效磷、速效钾和有效锰,PC2主要综合了有机碳、全氮、全钙和有效锌,有效铁对PC3具有较大的贡献。（3）对不同用地类型土壤养分的主成分得分进行排序,由大到小依次为火龙果地>林地>封育草地>玉米地,表明植树造林及火龙果种植等方式能有效改善石漠化区的土壤养分状况。建议对样区的石漠化治理应以封山育土为前提,以生态恢复为目的,通过种植火龙果与修复林地改善样区土壤状况,逐步形成生态环境与社会经济协调发展的石漠化综合治理体系。   相似文献   

丹阳天王寺边坡稳定性评价及防治措施     

余成  葛伟亚  常晓军 《江苏地质》2018,42(2):345-348

针对苏南地区典型露采边坡的地层岩性及地质构造特点,以极限平衡理论为基础,运用GeoStudio软件中的SLOPE/W模块和VADOSE/W模块计算分析江苏丹阳天王寺边坡在天然工况、暴雨工况及地震工况下的稳定性。结果表明:天然工况下,潜在滑动面分布范围最小,稳定性最高,存在滑动的危险性;暴雨工况下,潜在滑动面分布范围有所增大,稳定性降低,边坡滑动的可能性较大;地震工况下,潜在滑动面分布范围最广,稳定性最低,边坡滑动的可能性很大。基于上述结果,提出防治措施。  相似文献   

大兴安岭北段扎兰屯地区晚古生代早期花岗质岩浆作用——对额尔古纳 兴安地块和松嫩地块拼合时限的制约   总被引：1，自引：0，他引：1  

钱程  陆露  秦涛  李林川  陈会军  崔天日  江斌  那福超  孙巍  汪岩  吴新伟  马永非 《地质学报》2018,92(11):2190-2214

扎兰屯地区位于二连 贺根山 黑河构造带中段,区内发育韧性变形叠加的晚古生代早期花岗岩类。本文在详尽的野外地质调查基础上,对该套花岗岩类的锆石U- Pb年代学和地球化学进行系统分析,研究其成岩年代序列,探讨岩石成因及构造背景,厘定韧性构造叠加的时限,进一步揭示扎兰屯地区额尔古纳 兴安地块和松嫩地块的拼合过程,为兴蒙造山带的区域构造演化研究提供新材料。大量年代学研究显示,扎兰屯地区晚古生代早期花岗质岩浆作用发生于405~325Ma之间,该作用可进一步细化为早中泥盆世(Ⅰ期、405~380Ma)、晚泥盆世—早石炭世初(Ⅱ期、365~350Ma)和早石炭世晚期(Ⅲ期335~325Ma)等3期。其中Ⅰ期和Ⅱ期花岗岩类属高钾—钾玄质钙碱性、准铝质—弱过铝质花岗岩类,可能为俯冲背景下岛弧岩浆活动形成的I型 分异I型花岗岩;Ⅲ期花岗岩类属中—高钾钙碱性、准铝质—弱过铝质花岗岩类,可能为后碰撞背景下岩浆活动形成的分异I型- A型花岗岩。该套花岗岩类普遍叠加韧性变形,可能为碰撞后侧向逃逸作用的产物,变形时限为晚石炭世末—早二叠世(308~290Ma)。大兴安岭北段晚古生代早期花岗质岩浆作用与额尔古纳 兴安地块和松嫩地块的碰撞拼合作用有关,扎兰屯地区二者的碰撞拼合时限可能为早石炭世中期。  相似文献