排序方式： 共有83条查询结果，搜索用时 15 毫秒
61.
“皮壳—葡萄状”白云岩是一种非常特殊结构的白云岩。文中报道了塔里木盆地西北缘东二沟及塔北星火101井上震旦统奇格布拉克组中皮壳—葡萄状白云岩特征,并对其成因进行了探讨。皮壳状—葡萄状白云石中发育明、暗纤状白云石或纹层条带的含少量细晶的纤状—细粒状白云石以及肾状和葡萄状粉细晶白云石;由球形、杆形、孢子形等蓝细菌构成泡沫状结构;明暗、环带状橙红色光或中等橙红色光、核部发光较暗或不发光;与基质白云石相比,葡萄—皮壳状白云石δ 13 C PDB δ 18 O PDB δ 18 O PDB δ 13 C PDB δ 18 O PDB δ 13 C PDB
62.
中西部冲断带形成于两古板块"镶嵌式"拼接成陆后的再冲断.多尺度地球物理资料解释表明,浅层构造变形具有"横向有序分带、垂向多属性分层、纵向差异分段"特征,深部构造变形表现为分层解耦和差异收缩,造山带与盆地的岩石圈在咬合冲断时强-弱层对置.本文利用物理模拟实验和延时摄影方法,基于"挤压-碰撞"模型正演了冲断带变形过程,实验结果表明:造山带仰冲盆地并相互拼接,前者冲起折返,后者前陆冲断;盆内滑脱层的存在会产生构造分层,上构造层的变形以断层相关褶皱为主,且扩展范围受控于滑脱层;上构造层的挤压缩短量比下构造层大,变形扩展更远;下构造层的变形以叠瓦构造和双重构造为主,其断层倾角由前陆向腹陆逐渐增大,断面由下凹变为上凸,断片由侧向叠置变为垂向叠置;高角度逆断层的变形经历了脆性变形、韧-脆性变形和韧性变形三个阶段. 相似文献
63.
借助色谱质谱仪，对黔南坳陷和黔北坳陷凯里残余油藏凯棠剖面液态石油、岩孔古油藏中的热裂解焦沥青和研究区发育的震旦系陡山沱组、下寒武统牛蹄塘组、上奥陶统五峰组和下志留统龙马溪组四套高演化烃源岩的饱和烃和芳烃馏分进行了分析研究。尽管已有研究认为凯里残余油藏和岩孔古油藏的油源岩均是下寒武统牛蹄塘组，但它们具有完全不同的三芳甾类分布与组成。如凯里残余油藏凯棠剖面的液态原油中C28三芳甾烷优势明显，其含量相当于C26+C27三芳甾烷之和的一倍，且三芳甲藻甾烷在甲基三芳甾烷中的含量极低，它与其他甲基三芳甾烷的比值介于0.02~0.05；而在岩孔古油藏的焦沥青中，C26-28三芳甾烷的相对含量呈现C27 >C28 >C26的趋势，三芳甲藻甾烷丰富，它与其他甲基三芳甾烷的比值约为0.50，即比前者高一个数量级，这与研究区四套高演化烃源岩中三芳甾类标志物的分布与组成十分相似。值得注意的是与常规甾、萜烷生物标志物一样，三芳甾类标志物的分布与组成在四套高演化烃源岩中也出现了明显的趋同现象，从而失去了其在油源研究中的实用价值。因此，在利用常规甾、萜烷和三芳甾类标志物开展油源研究时，应尽可能在成熟度相近的地质样品之间进行，且样品的成熟度应限制在生油窗范围内。 相似文献
64.
随着四川盆地海相常规天然气和页岩气勘探开发的成功，新区、新层系的油气勘探逐渐提上议程。云南地区泥盆系泥页岩在局部地区广泛分布，有机质丰度较高，但钻井工作很少，研究较为薄弱，油气富集情况不明。通过野外调查，在云南禄劝地区中泥盆统华宁组发现了液态油苗。有机地球化学分析表明:油苗与中泥盆统华宁组三段的泥灰岩亲缘关系较好；中泥盆统华宁组三段的泥灰岩整体沉积于强还原—还原环境，生烃母质主要为藻类等低等水生生物，也有来自高等植物的贡献，已处于成熟阶段，具有较强的油气生成能力，生烃能力与Ⅱ1型烃源岩相当；康滇古陆西缘泥盆系泥灰岩有过生油气过程，生成的原油以饱和烃和芳香烃为主，且保存条件好的情况下，具有一定的页岩油气和常规油气勘探前景。 相似文献
65.
66.
近年来在塔里木盆地西南巴麦地区巴探5井石炭系卡拉沙依组中发现了多层煤层和炭质泥岩,它们具有一定的生烃潜力。由于它们发育于碳酸盐岩与砂泥岩交互的混积台地背景中,之前并未作为有效烃源岩加以重视,因此查明其发育规律和分布特征对寻找该区石炭系自生自储油气藏具有重要意义。利用钻井岩心、岩屑样品地球化学测试,测井岩性识别、三维地震反演等方法进行了该套煤系烃源岩生烃指标和识别分布研究。结果表明,巴探5井这套煤系烃源岩与卡拉沙依组广泛发育的一套三角洲-潟湖沉积体系有关。煤系烃源岩最大累计厚度约20 m,其有机碳含量介于10.6%~63.2%之间,干酪根类型为II2-III,镜质体反射率为0.78%~1.65%,其成熟度随埋深的变化总体上呈北低南高之势。煤、炭质泥岩、暗色泥页岩等有效烃源岩都表现为声波时差>300 μs/m、密度<2.3 g/cm3,所不同的是煤层自然伽马(GR)值小于75 API,炭质泥岩GR值为75~100 API,泥页岩GR值>100 API。井间和井外地区根据三维地震波阻抗反演值<7 333 m·s-1·g·cm-3识别出烃源岩的分布,它们主要沿来自北西向的朵状三角洲地区加厚。混积台地中煤系烃源岩和三角洲储层有望形成该区卡拉沙依组自生自储油气藏。 相似文献
67.
分子标志化合物在前寒武纪古海洋生命演化和古环境的研究中发挥着越来越重要的作用。在华北克拉通宣隆坳陷中元古界下马岭组黑色页岩中检测到一系列典型分子标志化合物,其特征表现为明显的“UCM”鼓包,高丰度的甲基支链烷烃、C24四环萜烷、C19-C2013β（H）,14α（H）-三环萜烷、13α（正烷基）-三环萜烷系列以及四类重排藿烷化合物,甾烷系列化合物的缺失,其组成特征及其地质意义明显不同于显生宙沉积物。甾烷系列化合物缺失可能是异养微生物转化和降解的结果,不能否定真核藻类在14亿年前古海洋的局部繁盛,但生物群落仍以原核生物为主。 相似文献
68.
四川盆地下侏罗统自流井组发育东岳庙段和大安寨段两套富有机质页岩层系,主要为湖泊相的页岩夹粉砂岩、介壳灰岩。基于页岩、介壳灰岩和粉砂岩之间的组合特征,自流井组共识别出3类7种页岩岩相组合类型。页岩有机质丰度中等,有机质类型以Ⅱ1、Ⅱ2型为主,热演化程度中等,油气共存。页岩储集空间既有无机孔,也有有机质孔,局部发育微裂缝。自流井组页岩中无机矿物与有机质、有机质与有机质孔的配置关系控制着页岩源—储配置的有效性,在较高的演化程度下,随着TOC的增大有机质孔隙度增大,页岩的源—储配置关系变好。刚性矿物稳定支撑格架下保存的固体沥青个体大,内部有机质孔数量多、孔径大;黏土矿物不稳定支撑格架下保存的沥青呈长条形,内部的有机质孔孔径较小。基于页岩层系不同岩性源—储耦合条件评价结果,页岩的源—储耦合条件明显优于夹层,源—储耦合条件好的优质页岩层段是页岩油气的甜点层段,其中黏土质页岩最好,介壳灰质页岩、粉砂质页岩为次;介壳灰岩和粉砂岩夹层不具备烃源条件且储集条件差,只能与相邻的富有机质页岩形成近源聚集体系。 相似文献
69.
Petrographic analysis of hydrocarbon inclusions in reservoirs is the basis and prerequisite for study of hydrocarbon charge history using fluid inclusion analysis.Samples from Silurian reservoirs in the Kongquehe area were studied with microscopy,cathode luminescence and scanning electron microscopy,and the paragenetic sequence of diagenetic events was established.Aqueous and oil inclusions were found in four different occurrences,i.e.,① in healed cracks in detrital quartz grains,② in quartz overgrowths that were formed relatively early in diagenesis,③ in healed cracks crosscutting quartz overgrowths and detrital quartz,and ④ in paragenetically late calcite cements.Solid bitumens were found in intergranular pores and in late fractures,whereas gas inclusions occur in healed cracks crosscutting quartz overgrowths and detrital quartz.The homogenization temperatures of aqueous(Th_(aq)) and oil incluisons(Th_0) within individual fluid inclusion assemblages are very consistent,suggesting that the microthermometric data are reliable.The Th_(aq) values are generally larger than Th_0,indicating the oil charging events took place at significant depths.The results suggest that there were at least two episodes of hydrocarbon charging in the Kongquehe area:the early hydrocarbon charging occurred in late Caledonian,dominated by oil,and the late hydrocarbon charging occurred in the Yanshan-Himalayan,first by oil and then gases.In addition,two episodes of hydrocarbon reservoir adjustment and destruction occurred in the Hercynian and Himalayan,respectively,forming solid bitumen. 相似文献
70.
《International Geology Review》2012,54(2):182-211
The Mesozoic lithospheric mantle beneath the North China craton remains poorly constrained relative to its Palaeozoic and Cenozoic counterparts due to a lack of mantle xenoliths in volcanic rocks. Available data show that the Mesozoic lithospheric mantle was distinctive in terms of its major, trace element, and isotopic compositions. The recent discovery of mantle peridotitic xenoliths in Late Cretaceous mafic rocks in the Jiaodong region provides an opportunity to further quantify the nature and secular evolution of the Mesozoic lithospheric mantle beneath the region. These peridotitic xenoliths are all spinel-facies nodules and two groups, high-Mg# and low-Mg# types, can be distinguished based on textural and mineralogical features. High-Mg# peridotites have inequigranular textures, high Mg# (up to 92.2) in olivines, and high Cr# (up to 55) in spinels. Clinopyroxenes in the high-Mg# peridotites are generally LREE-enriched ((La/Yb)N>1) with variable REE concentrations, and have enriched Sr–Nd isotopic compositions (87Sr/86Sr = 0.7046–0.7087; 143Nd/144Nd = 0.5121–0.5126). We suggest that the high-Mg# peridotites are fragments of the Archaean and/or Proterozoic lithospheric mantle that underwent extensive interaction with both carbonatitic and silicate melts prior to or during Mesozoic time. The low-Mg# peridotites are equigranular, are typified by low Mg# ( < 90) in olivines, and by low Cr# ( < 12) in spinels. Clinopyroxenes from low-Mg# peridotites have low REE abundances (ΣREE = 12 ppm), LREE-depleted REE patterns ((La/Yb)N < 1), and depleted Sr–Nd isotopic features, in contrast to the high-Mg# peridotites. These geochemical characteristics suggest that the low-Mg# peridotites represent samples from the newly accreted lithospheric mantle. Combined with the data of mantle xenoliths from the Junan and Daxizhuang areas, a highly heterogeneous, secular evolution of the lithosphere is inferred for the region in Late Cretaceous time. 相似文献