Early Cretaceous volcanism in the northern Songliao Basin,NE China,and its geodynamic implication     

F.Q. Zhang  H.L. Chen  X. Yu  C.W. Dong  S.F. Yang  Y.M. Pang  G.E. Batt 《Gondwana Research》2011,19(1):163-176

The Songliao Basin is characterized by episodic rifting and intense volcanism during its early development, and forms a key concealed part of the Late Mesozoic magmatic province of NE China. Few precise geochronological and geochemical data were previously available for the volcanic elements of this basin, restricting understanding of its geodynamic setting and evolution. We present new SHRIMP U–Pb zircon ages and geochemical data for the volcanic rocks from the northern Songliao Basin, which limit this volcanism to the Early Cretaceous period (115–109 Ma). Although dominated by rhyolite, the rocks cover a wide compositional spectrum encompassing trachyandesite, basaltic trachyandesite, trachyte and dacite. This suite exhibits a range of geochemical signatures characteristic of subduction-related genesis, falling into a high-K calc-alkaline series, with enrichment in large ion lithophile elements (LILE) and light rare earth elements (LREE), and weak depletion in high field strength elements (HFSE) and heavy rare earth elements (HREE). The suite also shares a common isotopic composition, consistent with derivation from partial melting of a single depleted mantle source. This Early Cretaceous volcanism occurred in an extensional back-arc setting associated with the subduction of the Paleo-Pacific plate, large scale upwelling of the asthenosphere, and intensive lithospheric thinning of the eastern continental margin of NE China which may have lasted until ca. 109 Ma.  相似文献   

惠民凹陷临北地区小断层识别及形成机理物理模拟     

肖凡  苏朝光  吴孔友  马玉歌 《地质与资源》1992,28(6):570-575

在高精度三维地震资料基础上，通过信号强化、大比例显示及蚂蚁体追踪技术，在剖面上建立了小断层的识别标志：1）同相轴的轻微错断；2）同相轴的分叉、合并；3）同相轴的挠曲、强相位转换；4）反射零乱或出现空白带；5）同相轴突然增减或消失，波组间隔突然变化，表现为不连续；6）借助蚂蚁体剖面识别小断层.通过分析临北地区不同规模断层的空间组合样式，利用平衡剖面原理，恢复了不同规模断层的演化过程.构造物理模拟显示，临北地区小断层主要为主干断层活动的派生或伴生构造，大断层附近的区域应力场是其主要形成原因，形成的小断层多与大断裂平行，呈平行式分布.  相似文献   

复杂地质体中煤系地层的大地电磁测深法识别技术 ——以合肥盆地石炭二叠系煤系地层识别为例     

王亚琳  邹文勇  裴磊 《物探与化探》2008,32(2):159-162,167

合肥盆地上古生界煤系地层在地震剖面上以叠瓦冲断片的形式构成中生界盆地的基底,且部分地区反射特征不明确,利用地震资料难以追踪和描述其空间分布。在利用电法资料研究该区的过程中,应用拟地震处理﹑地质分层成像处理和三维成像处理等新的技术和方法,较好地提取了合肥盆地石炭—二叠系的电性层。以此为基础,在地震剖面上进行了煤系地层的追踪,初步掌握了石炭—二叠系的分布,为盆地深化研究奠定了基础。  相似文献   

基于密度模型稀疏表征的重力反演方法     

于会臻  王金铎  王千军 《地球物理学报》2021,64(3):1061-1073

重力反演是恢复地下密度空间分布的有效工具,而选择合理的密度模型约束方法是提升重力反演分辨率和可靠性的关键.常规约束方法大多是从剖分网格空间中的密度模型出发,通过调整光滑或稀疏约束权重来匹配反演目标,但当地质体类型多样、异常分离不准确及网格剖分方案不合理时,模型约束的合理性与灵活性难以得到有效保证.为此,本文提出了一种基于密度模型稀疏表征的重力反演方法.首先假设待反演的密度模型表征为模型特征矩阵和稀疏分解系数的线性组合,之后重新推导了重力反演目标函数,并给出了分解系数的稀疏求解过程.相比现有重力反演方法,用于构建模型特征矩阵的特征模型可包含不同类型地质体的先验几何信息,分解系数的稀疏性保证了待反演目标来自于最典型的地质模式组合.最后,通过模型试验及实际资料验证了基于密度模型稀疏表征的重力反演方法的有效性.  相似文献   

东营凹陷泥页岩矿物组成及脆度分析   总被引：5，自引：0，他引：5  

李钜源 《沉积学报》2013,31(4):616-620

对东营凹陷泥页岩矿物组成、脆度进行了系统研究,并与北美页岩进行了对比。研究表明:东营凹陷沙三下和沙四上亚段泥页岩主要由黏土矿物、陆源碎屑矿物（主要指石英和长石）和自生非黏土矿物（主要指碳酸盐和黄铁矿）三部分组成;泥页岩黏土矿物含量平均只有25％左右,远低于海相泥岩和传统观点;石英含量平均为29%,远低于海相页岩;长石含量平均约5％,高于海相泥岩;自生的碳酸盐矿物含量较高,平均约37％;分析认为,陆相盆地面积较小、距物源区近以及相变快是导致研究区泥页岩矿物组成特征的主要原因。鉴于此,提出了新的脆度计算方法并计算了东营凹陷泥页岩的石英脆度、碳酸盐脆度和总脆度。对比发现,碳酸矿物盐含量与泥页岩脆度相关性较好,是影响泥页岩脆度的主要因素。最后指出:研究区泥页岩脆性较好,易于形成天然裂缝或被压裂,是页岩气潜在的有利储层。  相似文献   

塔河油田AT9井区丛式井钻井实践与认识     

刘晓民  马庆涛  周伟  张铎远  张颖 《探矿工程》2013,40(12):50-53

为了解决塔河油田环保要求高、征地难度大、开发管理不便等难题, AT9井区首次采用丛式井钻井技术对碎屑岩油藏进行综合开发部署。针对AT9井区地质工程难点及丛式井直井段防碰的特殊要求,对井位选址、平台布局、井眼轨道及井身结构进行优化设计。详细介绍了钻井过程中采用的MWD随钻监测防碰、PDC＋直螺杆复合钻井、钻井液等关键钻井技术,分析了丛式井组的技术合理性和开发经济性,验证了丛式井钻井技术在AT9井区的适用性,为塔河油田的经济高效开发进行了有效的探索。  相似文献   

济阳坳陷新生代盆地结构差异性及成因机制          下载免费PDF全文

张奎华  薛雁  吴智平  聂文龙  胡加山 《地质科学》2016,(2):561-575

通过断层活动性分析、典型测线平衡剖面恢复、伸展率统计等方法, 对济阳坳陷新生代盆地结构的静态特征和演化过程进行了详细分析, 从凹陷内部结构差异、不同凹陷间结构差异、区域结构差异3个层次上对济阳坳陷盆地进行了对比分析并探讨了成因机制.研究结果表明: 凹陷内部及不同凹陷间结构的差异主要受控于北西向控盆断裂以及不同演化阶段控盆断裂体系的发育, 而区域结构差异主要受控于板块俯冲方式转变下的郯庐断裂带由左旋走滑到右旋走滑的转型以及深部地幔物质由上涌到下沉的转变.  相似文献   

Shale Lithofacies and Sedimentary Environment of the Third Member, Shahejie Formation, Zhanhua Sag, Eastern China     

ZHU Xiaomin  ZHANG Meizhou  ZHU Shif  DONG Yanlei  LI Chao  BI Yuequan  MA Lichi 《《地质学报》英文版》2022,96(3):1024-1040

Researches into shale lithofacies, their sedimentary environments and relationship benefit understanding both of sedimentary cycle division and unconventional hydrocarbon exploration in lacustrine basins. Based on a 100~300-m-thick dark shale, mudstone and limestone encountered in the lower third member of the Eocene Shahejie Formation (Es3l member) in Zhanhua Sag, Bohai Bay Basin, eastern China, routine core analysis, thin sectioning, scanning electron microscopy (SEM), mineralogical and geochemical measurements were used to understand detailed facies characterization and paleoclimate in the member. This Es3l shale sediment includes three sedimentary cycles (C3, C2 and C1), from bottom to top, with complex sedimentary characters and spatial distribution. In terms of the composition, texture, bedding and thickness, six lithofacies are recognized in this succession. Some geochemical parameters, such as trace elements (Sr/Ba, Na/Al, V/Ni, V/(V + Ni), U/Th), carbon and oxygen isotopes (δ18O, δ13C), and total organic carbon content (TOC) indicate that the shales were deposited in a deep to semi-deep lake, with the water column being salty, stratified, enclosed and reductive. During cycles C3 and C2 of the middle-lower sections, the climate was arid, and the water was salty and stratified. Laminated and laminar mudstone–limestone was deposited with moderate organic matter (average TOC 1.8%) and good reservoir quality (average porosity 6.5%), which can be regarded as favorable reservoir. During the C1 cycle, a large amount of organic matter was input from outside the basin and this led to high productivity with a more humid climate. Massive calcareous mudstone was deposited, and this is characterized by high TOC (average 3.6%) and moderate porosity (average 4%), and provides favorable source rocks.  相似文献   

古物源体系多方法表征     

杨棵  朱筱敏  杨怀宇  朱世发  董艳蕾  金磊  申婷婷  叶蕾 《沉积学报》2022,40(6):1542-1560

古物源体系是深时“源—汇”系统研究的重要环节。随着沉积学理论和技术的发展,物源示踪的表征方法已从单一迈向综合、由定性走向定量,这将有助于更全面地揭示母岩发育特征、物源区构造背景、沉积物路径系统等,进而建立更可靠的古物源体系发育模式。碎屑锆石U-Pb定年等多方法物源体系表征研究表明,沾化凹陷渤南洼陷沙四下亚段（Es4x）砂岩样品主要发育岩浆成因的锆石,这些锆石颗粒自形程度较好,具有清晰的岩浆环带,其Th/U>0.4,稀土元素普遍具有“Ce正异常、Eu负异常”特征。微量/稀土元素地球化学指标和砂岩岩石学特征揭示了研究区沙四下亚段陆源碎屑具有岩浆岛弧/活动大陆边缘酸性花岗质源岩的属性。母岩的发育与华北克拉通在新太古代—古元古代及晚古生代—中生代的地球动力学背景密切相关。综合优势年龄贡献、母岩属性、岩石学特征、地球动力学背景,最终建立了渤南洼陷沙四下亚段古物源体系发育模式,即渤南洼陷沙四下亚段同时发育“近源堆积”和“远源供给”两类路径系统,发育东侧中生界岩浆岩主导型物源系、南侧新太古界/古元古界/上古生界/中生界母岩联合控制型物源系、中部混合物源系。其中,东侧物源系和中部物源系的关联性较大,应属于同一沉积物路径系统,南侧物源系相对独立。  相似文献   

Early Cretaceous Thrust and Nappe Tectonics in North Qilian Shan,Northern Tibetan Plateau: Evidence from Field Mapping,Geochronology, and Deep Structural Analysis     

HAN Lele  DING Weicui  CHEN Xuanhu  SHAO Zhaogang  ZHANG D  XIAO Yongjun  HE Chengguang  WANG Zengzhen  LI Bing  ZHANG Yiping  XU Shenglin  WANG Ye 《《地质学报》英文版》2023,97(4):1058-1077

The North Qilian Shan fold and thrust belt, located at the northern Tibetan Plateau and southern margin of the Hexi Corridor, is a key tectonic unit to decode the formation and expansion of the plateau. Previous studies emphasize the Cenozoic deformation due to the far-field response to the Indo–Asian collision, but the Mesozoic deformations are poorly constrained in this area. We conducted detailed field mapping, structural analysis, geochronology, and structural interpretation of deep seismic ...  相似文献