塔西台地寒武纪沉积环境演化与海陆耦合     

刘沛显  关平  冯帆  贾文博  张巍  邓世彪  金亦秋 《沉积学报》2016,34(6):1092-1107

碳酸盐岩台地作为陆地与深海间的过渡带,其沉积记录了海洋和邻近陆地的演化。结合已有的沉积学工作,对塔里木盆地西部台地寒武系碳酸盐岩进行全岩及酸不溶物地球化学研究。塔西台地寒武纪主要发育局限台地、局限-蒸发台地或蒸发台地相沉积。碳酸盐岩的地球化学特征主要受沉积环境和成岩作用影响,对研究区寒武系白云岩来说,其元素组成极易受沉积微相的控制,氧同位素组成则很可能已被成岩作用改造,仅原生、准同生白云岩的Sr/Ba、Fe/Mn和C同位素可反映沉积相演化对应的古盐度、离岸距离等沉积环境特征的变化,酸不溶物化学蚀变指数（CIA值）则指示邻近陆地的化学风化强度与气候特征。寒武纪时期,塔西台地在相对海平面较高时发育局限台地相沉积,以水体盐度较低、沉积环境离岸较远和生物活动相对较弱为特征,陆地化学风化强度适中,气候温暖湿润;在相对海平面较低时发育蒸发台地相沉积,具有水体盐度较高、沉积环境离岸较近和生物活动相对较强等特点,陆地化学风化强烈,气候炎热极端;在相对海平面适中时发育局限-蒸发台地,沉积环境和邻近陆地的特征介于前述二者之间。沉积相演化对应的较长周期的海陆演化可能主要受全球海平面升降及宏观气候变化控制,具体表现为相对海平面升降所导致的海相沉积环境的变化,以及气候变化引起的陆地化学风化强度的变化。寒武纪塔西台地所处区域的海洋-陆地演化具有高度耦合的特征。  相似文献   

Testing and modeling of the mechanical behavior of dolomite in the Wudongde hydropower plant     

J. C. Zhang  W. Y. Xu  H. L. Wang  Q. X. Meng 《Geomechanics and Geoengineering》2016,11(4):270-280

In order to understand the mechanical behaviours of the surrounding rocks in the underground caverns of the Wudongde hydropower plant, triaxial tests are performed on a type of dolomite. It is revealed that damage induced by crack development is the main factor controlling the nonlinear plastic deformation and failure behaviour of the dolomite in both pre- and post-peak regimes. Based on this understanding, a coupled elastoplastic damage model is developed for capturing the dolomite’s mechanical behaviours. In the model, the effects of plasticity and damage on rocks is described by introducing plastic hardening and damage softening commonly in the plastic yield surface. Which are both derived from a suitable Helmholtz free energy function. The model is used to simulate the triaxial tests. Comparisons between test results and the numerical modelling show that the developed model is capable of describing the macro mechanical behaviours of the Wudongde dolomite.  相似文献   

从成岩-蚀变特征探讨塔深1井白云岩储层成因     

尤东华  王亮  胡文瑄  钱一雄  王小林  陈强路  张军涛 《岩石矿物学杂志》2018,37(1):34-46

塔深1井钻遇的寒武系地层属于中寒武统阿瓦塔格组和上寒武统丘里塔格下亚群。阿瓦塔格组以灰色-深灰色粉晶-细晶藻白云岩为主,丘里塔格下亚群以灰色-浅灰色晶粒结构白云岩与残余亮晶结构白云岩为主。藻白云岩在阴极发光下以明亮的中等强度砖红色-桔黄色为主要特点,具有相对偏重的δ18O值(-6.3‰~-4.5‰,平均为-5.3‰,VPDB)、相对较高的稀土总量以及与正常海相碳酸盐岩相似的稀土配分样式。晶粒白云岩与残余亮晶结构白云岩在阴极发光下以偏暗的中等强度蓝紫色-砖红色为主要特点,具有相对偏轻的δ18O值(-9.2‰~-5.7‰,平均为-7.5‰,VPDB)、相对偏低的稀土总量、Eu正异常与重稀土明显亏损为特点的稀土配分模式。阿瓦塔格组和丘里塔格下亚群白云岩在上述岩石学特征和地球化学特征上的差异表明储层发育的成岩-蚀变过程存在差异。研究认为,埋藏较深的阿瓦塔格组优质储层的形成受多种因素控制,其中准同生期大气淡水作用下石膏结核的溶解及非稳定碳酸盐矿物的溶解奠定了基础,后期成岩改造及流体作用进行了强化,局部遭充填破坏。  相似文献   

Hydrothermal Dolomite: A Review and PerspectiveEI北大核心CSCD     

Li Q.  Bao Z. 《大地构造与成矿学》2018,(4):699-717

Hydrothermal dolomite commonly closely associates with oil-gas reservoirs and sediment-hosted Pb-Zn deposits, the Mississippi Valley-type (MVT) Pb-Zn deposits in particular. Host rocks of MVT deposits usually experienced extensive dolomitization, and indeed, hydrothermal dolomite is considered as a useful prospective indicator for MVT mineralization. However, genetic link between the hydrothermal dolomitization and MVT Pb-Zn mineralization is a matter of debate. This paper briefly reviewed the nomenclature and research history of hydrothermal dolomite, introduced the major geological, geochemical characteristics, and distribution of hydrothermal dolomite, spatial and possibly genetic relationship between hdyrothermal dolomite and hdyrothermal ore deposits and oil-gas reservoirs based on case studies including the occurrence of hydrothermal dolomites in MVT deposits in Southwest China. The temporal and genetic relationships between dolomitizaiton and thermal sulfate reduction, sulfide precipitation and thus the location of ore mineralization well worthy more attention, and comprehensive geological and isotope geochemical and state of art in situ techniques will contribute to understanding of the genesis of hydrotherml dolomite and the spatially related ore deposits and oil-gas reservoirs. © 2018, Science Press. All right reserved.  相似文献   

Surface Geophysical Methods used to Verify the Karst Geological Structure in the Built-up Area: A Case Study of Specific Engineering-Geological Conditions     

Rene PUTISKA  Marian MARSCHALKO  Isik YILMAZ  Dominik NIEMIEC  CHENG Xianfeng  Ivan DOSTAL  Jan KUBAC 《《地质学报》英文版》2021,95(5):1763-1770

This article presents a research study of complex limestone karst engineering-geological conditions in the municipality Valaská near Banská Bystrica in Slovakia. The aim of the study is to demonstrate the impossibility of spatial identification of cave spaces using surface geophysical methods due to the specific engineering-geological conditions of a thick surface layer of anthropogenic fill containing highly heterogeneous anthropogenic material. Its maximum thickness is 3 m. Another specificific condition of the study area is its location in the built-up area, due to which the applicability of geophysical methods was limited. The article contains methodological recommendations to be used in analogous geological conditions with karst structures topped with anthropogenic fill, which complicates the identification of cave spaces. The recommended solution herein is the identification of the cave system using underground mapping of the karst and its projection onto the surface for which surface geophysical methods have been combined.  相似文献   

四川盆地东部中二叠统茅口组热液活动特征          下载免费PDF全文

李红  王良军  柳益群  曾韬  张冬冬  李文厚  周鼎武  杨康  董杨坤  彭毅峰 《古地理学报》2021,23(1)

四川盆地中二叠统茅口组存在丰富的热液流体活动。在野外剖面和岩心观察的基础上,利用多种分析测试方法,对四川盆地东部茅口组碳酸盐岩中的热液活动特征进行了探讨。研究区茅口组热液活动包括2类,一类为硅质热液,表现为薄层硅质岩或硅质团块;另一类为碳酸盐型热液,表现为粗晶方解石和白云石充填在张性构造裂缝中或呈"雪片状"集合体,偶见少量黄铁矿、闪锌矿等金属硫化物伴生。硅质岩主量元素之间的关系表明硅质来源具有多样性,是热液硅与壳源硅的混合;黄铁矿、闪锌矿原位S同位素δ34S介于-3.91‰~-6.87‰之间,推测可能受到了微生物和基性岩浆岩的双重影响;方解石脉和具鞍状双晶的白云石脉普遍具有Ca O高于标准计量、相对富Sr和U、贫REE和Ti、Ce/Ce*明显负异常、Eu/Eu*主体正异常、Y正异常等特征,表明碳酸盐脉为热液活动的产物,流体来源也呈现出火山活动相关流体与富钙地下水混合的特点。闪锌矿富集Ge和Cd,Zn/Cd及Zn/Fe值反映了中等成矿温度。硅质岩和碳酸盐流体包裹体均一温度变化范围较大,介于54.7~294.3℃之间,与稀土元素和微量元素比值所揭示的特征吻合。研究结果表明,穿层状硅质结核和团块的首次出现往往标志着茅口组热液活动的开始,而张性构造裂缝和碳酸盐型热液活动带来的围岩白云化作用则有效地改善了白云岩储集层的物性。  相似文献   

鄂尔多斯盆地奥陶系盐下白云岩储层特征、成因及分布     

丁振纯  高星  董国栋  唐瑾  惠江涛  王少依  赵振宇  王慧 《海相油气地质》2021,(1)

奥陶系盐下白云岩储层是鄂尔多斯盆地中东部天然气勘探的重要接替领域。基于钻井岩心、微观薄片、物性分析及地球化学特征等资料,应用微区多参数实验分析方法,对奥陶系盐下白云岩储层特征、成因与分布开展了系统研究。结果表明:①奥陶系盐下主要发育颗粒滩白云岩和微生物白云岩储层,其中颗粒滩白云岩储层岩性为砂屑白云岩、鲕粒白云岩和粉—细晶白云岩,储集空间由溶蚀孔洞、粒间孔、晶间(溶)孔和裂缝组成,平均孔隙度为6.04%;微生物白云岩储层岩性为凝块石白云岩,储集空间为溶蚀孔洞和微裂缝,平均孔隙度为5.64%。②奥陶系盐下白云岩储层孔隙来源于对颗粒滩和微生物丘中原生孔隙的继承,并经受了溶蚀作用、白云石化作用,以及膏盐矿物、石英、细—中晶白云石与方解石等充填作用的改造。③有利储层主要分布于中央古隆起、横山隆起及乌审旗坳陷中的低凸起带上。  相似文献   

川东及邻区上二叠统生物礁的白云岩化   总被引：15，自引：2，他引：15  

雷卞军  强子同 《地质论评》1994,40(6):534-543

白云岩化是川东及邻区上二叠统礁体的重要成岩事件。根据矿物岩石学、X光衍射、流体包裹体、碳氧稳定同位素、微量元素及阴极发光等项目的研究,笔者认为,礁体白云岩主要是埋藏交代成因,礁顶有少量微-粉晶白云岩为潮坪成因。本文着重讨论礁体围岩为生屑灰岩的埋藏压实流体白云岩化模式,简述礁控白云岩储集特征及其成因。在此研究基础上,提出了一个白云石结构成因分类方案。  相似文献   

双密度重叠找气新方法     

刘舒杰  谭廷栋 《物探与化探》1994,18(4):289-296

本文根据岩石孔隙中的天然气引起介电测井孔隙度减小和密度测井孔隙度增大的原理,建立了双密度重叠找气新方法,消除了岩性的影响,提高了测井找气的分辨率,增加了评价气层的直观性。该方法用于寻找陕甘宁盆地低孔隙白云岩气藏,获得了明显的地质效果。这种方法还可以在其它储层岩性气藏中应用。  相似文献   

连续测定方解石和白云石中碳、氧同位素比值的方法及其意义   总被引：1，自引：0，他引：1  

吴静淑  李金城  朱井泉 《岩石矿物学杂志》1990,(2)

本文提出了利用方解石和白云石二者的不同活性,在不同的温度条件下,在同一份碳酸盐岩样品中,连续测定碳、氧同位素比值的新方法。测定结果精度高,能用于判定白云石的成因,具有实用价值。  相似文献