川东北飞仙关组白云岩岩石结构演化   总被引：1，自引：1，他引：0  

杨博  蔡忠贤  赵文光 《现代地质》2010,24(5):945-950

根据矿物结晶学理论,白云石可按照晶体大小和晶边形貌划分为不同的结构,其结构的演化主要受原岩化学组成、岩石结构和白云岩化流体的影响。白云岩原岩可分为不同化学组分的泥灰岩和含颗粒泥灰岩,泥灰岩可细分为成分均匀的和含溶孔、胶结物的泥灰岩;含颗粒泥灰岩可细分为未接受任何改造的、发生溶蚀胶结作用的和发生泥晶化等作用的含颗粒泥灰岩。以川东北飞仙关组白云岩为例,在不同浓度的白云岩化流体条件中,讨论不同结构白云岩岩石的演化。结果表明：泥晶化及溶蚀作用是白云石岩石结构演化和形成的基础;大多数鲕粒白云岩在低浓度白云岩化溶液中形成;糖粒状白云岩为外来高浓度的白云岩化流体改造形成。  相似文献   

Stable Isotope Ratios and the Evolution of Acidulous Ground Water     

Martin Dietzel  Thorsten Kirchhoff 《Aquatic Geochemistry》2002,8(4):229-254

Ground waters in North Hesse (Germany) are conspicuous by high amounts of dissolved inorganic carbon (DIC) at low pH. The DIC is received from the uptake of soil CO₂ and CO₂ of volcanic origin and the subsequent dissolution ofTriassic and Permian limestone and dolomites. The volcanic CO₂ is related to Miocene basaltic magma which has liberated gaseous CO₂ during thebreakthrough to Triassic and Permian sediments. The volcanic CO₂ (-6 < ¹³CCO₂ < -3, PDB) was trapped within pore spacesand intra- and intergranulares of Permian evaporites and Triassic sandstones and was stored within such reservoirs until recent times. The uptake of volcanic CO₂ occurs as ground water migrates through such reservoirs. The ¹³ C/¹² C-signatures of the DIC indicate mixture of soil-CO₂and CO₂ of volcanic origin for the dissolution of marine limestone and dolomites. The obtained two types for CO₂ of volcanic origin with ¹³C_{CO 2}-values of -10 ± 3 and +2 ± 2 can be explained by diffusion of CO₂ through micropores, faults, and interfacesof solids. This mobilisation of CO₂ is accompanied with a kinetic fractionation of -9. ¹³ C-depleted CO₂ is liberated from the reservoir,whereas ¹³ CO₂ is accumulated in the residue  相似文献   

四川盆地普光大型气藏基本特征及成藏富集规律   总被引：121，自引：12，他引：121       下载免费PDF全文

马永生  蔡勋育  李国雄 《地质学报》2005,79(6):858-865

普光气田是在四川盆地近期发现的规模最大、埋藏最深、资源丰度最高的气田,2005年初向国家储委上交飞仙关组探明储量1144×108m3,普光气田已初步落实的三级储量超过3500×108m3。普光气田下三叠统飞仙关组储层岩性以单一的白云岩为主,发育鲕粒白云岩、残余鲕粒白云岩等储层;储层物性以中孔中渗、高孔高渗储层为主,为优质储层。深埋藏条件下的孔隙形成可能与深部热水溶蚀作用有关。临近主力生烃凹陷、优质储层发育、适时的古隆起可能是普光大型气田形成的有利条件。  相似文献   

Porosity–permeability relationships in Miocene carbonate platforms and slopes seaward of the Great Barrier Reef, Australia (ODP Leg 194, Marion Plateau)     

STEPHEN N. EHRENBERG  GREGOR P. EBERLI†  GREGOR BAECHLE† 《Sedimentology》2006,53(6):1289-1318

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Stratigraphic signatures of climatic change during the Holocene evolution of the Tigris–Euphrates delta, lower Mesopotamia     

Adnan A. M. Aqrawi   《Global and Planetary Change》2001,28(1-4)

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Authigenic dolomites in the Eocene–Oligocene organic carbon-rich shales from the Polish Outer Carpathians: Evidence of past gas production and possible gas hydrate formation in the Silesian basin     

《Marine and Petroleum Geology》2014

Eocene–Oligocene dolomite concretions and beds from the Grybów and Dukla units of the Polish Outer Carpathians were studied. These rocks occur in the organic carbon-rich, marine and fine-grained deposits of hemipelagic or turbiditic origin. Mineralogic, elemental and stable C and O isotopic composition of the dolomites was determined. Results indicate that the rocks were formed by precipitation of predominantly Fe-rich dolomite cement close to the sediment-water interface prior to significant compaction. The main source of bicarbonate for dolomite formation was bacterial methanogenesis as evidenced by the high δ¹³C values up to 16.6‰. The main source of alkalinity was probably weathering of silicate minerals which might have also liberated Ca and Mg ions for the dolomites to form. The distribution of these dolomites indicates that microbial methane production was widespread in the Silesian basin. Moreover, formation of some dolomites in the Eastern part of the Dukla unit was probably associated with gas hydrates as suggested by the elemental and oxygen isotopic composition of dolomitic matrix. Therefore, the dolomites may serve as a proxy of areas where biogenic methane was produced, where the rocks had high hydrocarbon potential, and where hydrates could have existed.Detailed mineralogic and petrographic analyses allowed for the reconstruction of the diagenetic sequence and the evolution of pore fluids. Textural relationships between successive cement generations indicate that the central parts of the composite dolomite crystals experienced corrosion and that the latest ankerite cement filled the secondary intragranular cavities within those crystals. This observation shows that reconstructions of pore fluid evolution based on core-to-rim analyses of such composite crystals may lead to wrong interpretations. Septarian cracks developed in the dolomites are often filled with multistage cements. The earliest generations are ferroan dolomite and ankerite cements which precipitated within the cracks simultaneously to the ferroan dolomite and ankerite cements from the matrix of the dolomitic rocks which shows that septarian cracking occurred very early, during the final stages of concretionary formation. These cements were followed by the late-diagenetic precipitates, mainly quartz, kaolinite and blocky calcite. This calcite is commonly associated with bitumen which shows that it precipitated during or after oil migration in the decarboxylation zone.  相似文献   

陆相页岩油勘探“进源找油”探索与思考——以渤海湾盆地歧口凹陷沙一段为例     

蔚远江  王红岩  刘德勋  赵群  郑民  王社教 《地球科学与环境学报》2021,(1):117-134

基于源岩油气理论和“进源找油”思想,创建提出了陆相页岩油“六定”思路(定背景、定源岩、定储层、定区带、定资源、定甜点)勘探流程,剖析其地质特征及与常规勘探流程的显著差异,并以渤海湾盆地歧口凹陷沙一段为例进行了论述。按“六定”思路地质评价认为,歧口凹陷在古近纪湖盆扩张和咸化环境下,半深湖—深湖、滨浅湖—湖湾相区分布广泛,发育了多个斜坡构造带,页岩油形成和聚集背景有利。沙一下亚段暗色泥岩、油页岩、富有机质页岩发育,厚度大,分布广,主体处于成熟生油阶段,生烃条件好。受内、外物源共同控制,沙一下亚段形成大面积分布的多期重力流沉积粉—细砂岩和泥—微晶白云岩储层,平均厚度为12.7~70.0 m,叠置发育,连片分布,整体呈低孔、特低—超低渗。沙一下亚段源储一体,发育4类源储配置,源储叠合区主要分布在凹陷中心、宽缓斜坡的中—低斜坡区和中斜坡区,纵向上浊积席状砂岩油层与白云岩油层叠置分布,并与高斜坡及裂缝带砂岩常规油藏横向连片。两类页岩油地质资源量合计中值为5.86×108 t,剩余资源占比大于60%,埋深适中,勘探潜力较大。沙一下亚段已有多口探井钻获工业油流,页岩油富集受构造、微相、成岩共同控制,发育致密砂岩、白云岩2类甜点体和4个甜点段,歧北低斜坡、歧南斜坡、板桥斜坡、歧北中斜坡是歧口凹陷近期勘探的有利甜点区。基于“进源找油”思想提出:需高度重视碳酸盐岩烃源岩生烃贡献和分布研究;应开拓一些“非常规思维”,探源岩(区)挖潜力、究储层找甜点、常规非常规结合立体综合勘探;要持续探索和重点攻关页岩油甜点区(段)识别和评价方法技术,解决选区评价面临的技术难题。  相似文献   

四川盆地西部中二叠统栖霞组晶洞充填物特征与热液活动记录   总被引：1，自引：1，他引：0  

黄思静  兰叶芳  黄可可  吕杰 《岩石学报》2014,30(3):687-698

热液环境在碳酸盐岩成岩作用中十分重要,MVT铅锌矿床和热液白云岩储层都与之有关。四川盆地西部中二叠统栖霞组普遍发育厘米级大小的晶洞,其充填物主要为晶体粗大的非平直晶面鞍形白云石,这些鞍形白云石经历了广泛的溶解作用,次生方解石充填于鞍形白云石溶解空间及其晶间孔隙中。本文在碳酸盐岩岩石学特征研究的基础上,测试了晶洞充填物的碳氧同位素组成、元素构成和包裹体均一化温度,结合川西中二叠统埋藏历史和二叠纪以来的非地热增温热事件,研究了晶洞充填物中鞍形白云石的沉淀与溶解流体,以及充填于鞍形白云石溶解空间和晶间孔隙中次生方解石的沉淀流体。研究表明:在作为晶洞充填物的碳酸盐矿物中,鞍形白云石和沉淀于白云石晶间、晶内的次生方解石具有显著不同的氧同位素组成和包裹体均一化温度,前者δ18O值-5.94‰～-4.35‰,包裹体均一化温度主要为110～210℃,后者δ18O值-10.34‰～-8.75‰,包裹体均一化温度主要为70～110℃,据此反演的鞍形白云石沉淀流体的δ18O值为+4‰～+14‰(SMOW),方解石相应值为-4‰～+5‰(SMOW),显示白云石是在高盐度和高温流体中沉淀的,方解石是在相对低盐度和低温流体中沉淀的;晶洞充填物的碳同位素分析表明,鞍形白云石和沉淀于白云石晶间和晶内的次生方解石的δ13C值大致分布在0.7‰～2.6‰的范围内,显著低于同期海水的δ13C值,两种碳酸盐矿物中的碳具有同期海水和深部CO2混合碳源的特征;中二叠世末东吴运动期间峨眉山玄武岩喷发时岩浆活动的热效应导致了当时处于浅埋藏环境的栖霞组地层中鞍形白云石的沉淀,而热事件后流体温度和盐度的同时降低则使得鞍形白云石溶解,同时伴随方解石沉淀在鞍形白云石溶解后的孔隙和晶间孔隙中。  相似文献   

云南会泽超大型铅锌矿床HTD白云岩的厘定及其形成机制     

文德潇  韩润生  王峰  贺姣姣  邱文龙  夏颜乐  陈随海  倪尔建 《岩石矿物学杂志》2014,33(6):1086-1098

会泽超大型铅锌矿床是世界著名的特富铅锌矿床之一,热液白云岩(HTD)是其赋矿围岩,本文在典型剖面精细测量和镜下鉴定的基础上,将矿区的白云岩划分为埋藏白云岩与HTD白云岩两类,并结合包裹体研究对HTD白云岩进行厘定,结果表明:1研究矿床HTD白云岩产出受NE向压扭性层间断裂控制,优先发育在断层上盘。2发育大量裂(孔)隙,溶孔具有线状与面状分布特征。3鞍状白云石颗粒粗大,呈肉红色、灰白色或棕色,具独特尖顶、他形鞍状、曲面鞍形、曲面接触、晶内微裂隙、溶孔,见波状消光与雾心亮边。4鞍状白云石呈厚层状产出,与黄铁矿等热液矿物共生,并发育晶洞充填物。5鞍状白云石具基质交代型和孔-缝充填型,在HTD白云岩与灰质白云岩狭窄过渡带,见伴随其形成而形成的斑马状构造、角砾状构造。6 NW向张性断裂带为构造流体运移通道,发育网脉状白云石化,其白云石包裹体均一温度高(250~438℃),盐度变化范围大(3.4%~17.2%)。NE向压扭性断裂带为构造流体成岩场所,控制厚层状白云石化展布,其白云石包裹体均一温度高(180~354℃),盐度低(1.1%~5.9%)。通过对矿区HTD白云岩形成的流体驱动机制、流体性质、裂(孔)隙特征、矿化指示分析,得出"在挤压背景下,受碳酸盐岩地层中的NE向压扭性层间断裂带控制"的HTD白云岩成因认识,即:1区域冲断褶皱作用是流体运移的深部动力机制;2偏酸性富CO2的中高温-中盐度流体在冲断褶皱构造系统内大量集聚,在其配套的NE向压扭性层间断裂上盘与膨胀部位形成厚层状白云岩。3裂(孔)隙对流体多期次与成岩强度具有指示意义。4 HTD白云岩岩性分带、成岩强度、构造特征(显微构造)对矿体产出具有指示意义。  相似文献   

渤海沙西北构造带下古生界碳酸盐岩潜山白云岩形成机制研究          下载免费PDF全文

华晓莉  李慧勇  孙希家  于海波  史盼盼 《高校地质学报》2018,24(6):833

通过岩心薄片、扫描电镜、碳氧锶稳定同位素、X衍射有序度及微量元素特征分析,系统研究了渤海湾盆地沙西北 构造带碳酸盐岩潜山白云岩的地球化学特征及成因机制。结果表明,沙西北构造带下古生界白云岩可划分为泥晶白云岩、 颗粒白云岩、泥质/灰质白云岩和鞍状白云岩四类,各类白云石特征差异明显。泥晶和颗粒白云岩δ18O大于-7‰,87Sr/86Sr值 与海水值接近,为0.7090~0.7120,Na2O含量较高,大于0.06%,有序度偏低,薄片中可见石膏,为准同生成因。泥质/灰质 白云岩为细晶结构,δ18O偏负,为-8‰~-10‰,87Sr/86Sr为0.7120~0.7140,Na2O含量降低,有序度变大,镜下见次生加大亮 边,为埋藏成因。鞍状白云岩为中粗晶结构,贫δ18O,87Sr/86Sr较高,薄片中见辉绿岩,为热液成因。本区白云岩以准同生 和埋藏成因为主,局部沿断裂可能存在热液成因。奥陶系沉积时期主要发生埋藏白云石化和溶蚀作用,是增加白云岩有效 孔隙的重要阶段,为优质储层形成起到了建设性作用。  相似文献