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1.
滇西宁蒗-丽江地区泥盆系白云岩的成因 总被引：2，自引：1，他引：2
本区泥盆系主要为一套碳酸盐岩沉积物,以白云岩为主。其形成机理以混合水白云石化作用为主。以白云岩镜下结构为飘浮菱面体结构、接触菱面体结构、直边镶嵌结构及缝合镶嵌结构。阴极发光和电子探针分析结果表明:混合云化形成的白云石从中心到边缘,Fe++、Mn++富集,K+贫化,形成白云石雾心亮边的特点,阴极发光则表现为具核心和环带。在地下成岩及深埋环境中,巨晶白云石在单偏光下具褐色环带,阴极发光下因富铁而呈黑红色-不发光。 相似文献
2.
准噶尔盆地西北缘二叠系云质碎屑岩地球化学特征及成因机理研究 总被引：1，自引：0，他引：1
通过岩石学、碳氧同位素和元素地球化学等方法对准噶尔盆地西北缘二叠系云质碎屑岩特征进行了研究,分析了白云岩化机理并建立了白云岩化作用成因模式。结果表明,研究区岩石类型为白云质泥岩、白云质粉砂岩、白云化凝灰质粉砂岩和白云化凝灰质泥岩等,白云石化以交代湖相灰泥质和硅质（凝灰质）组分形成的自形或半自形的粉晶-细晶白云石为主,常见残余方解石和晚期方解石胶结物充填。岩石中 V/ Ni比（1.2～4.8）、Sr含量（95.5～782.2 μg/g）、Mg/Ca比（0.5～3.0）、有序度（0.36~0.98）、δ18OPDB（-14.8‰～3.2‰）和δ13CPDB（-1‰～5.2‰）的变化范围都较大。研究区云质岩类形成于水动力条件较弱、水体较深、相对安静的半闭塞陆相微咸-咸水湖湾环境,具多期次成因;二叠系时期构造运动复杂,断裂发育,火山活动频繁,不仅提供了白云石化过程中Mg2+的来源,且为富镁流体的快速流动和渗透提供了通道。综合研究认为本区的云质岩有准同生白云岩化、埋藏白云岩化和热液白云岩化三种成因类型。 相似文献
3.
《Engineering Geology》2002,63(1-2):17-29
Effects of porphyrotopic textures on expansion of dolomitic limestone aggregates due to alkali–carbonate reaction (ACR) are presented. The dispersed distribution of dolomites in the texture of aggregates can be divided into pophyrotopic-M, psedoporphyrotopic-M and porphyrotopic-S types. It is proved that porphyrotopic textures are more important to ACR expansion than lithologic species of dolomitic limestones. The dolomitic limestones with both porphyrotopic-M or psedoporphyrotopic-M texture and the small size of dolomite crystals are expected to be highly alkali–carbonate reactive. These aggregates can be found not only in dolomitic micritic limestones but also in dolomitic micritic allochemical limestones as well as dolomitic sparry allochemical limestones. 相似文献
4.
二连盆地阿南凹陷下白垩统腾格尔组发育一套湖相的富含致密油云质岩段,包括云质泥岩、云质沉凝灰岩和云质砂岩,但这类云质岩中的白云石岩石学特征及成因尚不明确.通过岩心、薄片、扫描电镜及碳氧同位素分析,将云质岩中的白云石分为两类:(1) 分布在纹层状和星点状云质泥岩或云质沉凝灰岩的非平直晶面、半自形微粉晶白云石;(2) 分布在块状云质沉凝灰岩或云质砂岩的非平直-平直晶面、自形粉细晶白云石.两类白云石的成因机制不同:(1) 半自形微粉晶白云石具偏高的δ13CPDB值(平均为5.4‰),主要受产甲烷菌的代谢活动影响,其δ18OPDB值负偏移量较小(平均为-13.0‰),计算形成温度约50~75 ℃,推测为成岩早期成因白云石,Mg2+离子主要来源于富火山灰的凝灰物质大量水解.(2) 自形粉细晶白云石晶体较大、晶形好,其δ13CPDB值偏低(0.2‰~0.7‰),受产甲烷菌的代谢活动和深层有机质热催化共同影响,其δ18OPDB值较低(平均为-19.4‰),计算形成温度约119 ℃,推测为成岩晚期埋藏成因白云石,Mg2+离子可能与粘土矿物水解及深部流体上涌有关. 相似文献
5.
The Jubaila Formation (Upper Jurassic) in central Saudi Arabia has been divided into lower, middle, and upper parts purely on lithologic grounds. Each part consists of a major lower unit of lime mudstone and a minor upper unit of grainstone. This persistent change in the limestone facies is interpreted as a reflection of repeated shoaling up in the depositional shelf environment. It is a normal marine carbonate sequence that varies in thickness from 85 to 126 m. In the Hanifa Formation, the lowermost brown ledges in the section comprise a series of coarsening upward sequences which generally terminate in a fossiliferous/peloidal packstone and grainstone and subordinately lime mudstone facies. The middle slope member is yellow, blocky weathered shale and marl. Above this slope member are several thick beds of brown-coated fossiliferous wackestone, packstone, and grainstone with the association of lime mudstone in certain levels. These are fairly resistant ledges due to the occurrence of stromatoporoids. Dedolomitization occurs in the Jubaila Formation in various textural forms which include composite calcite rhombohedra, zonal dedolomitization, regeneration of predolomitization fabric of the limestone, and coarsely crystalline calcite mosaics with or without ferric oxide rhombic zones. Rhombohedral pores commonly occur in intimate association with dolomite, possibly resulting from the leaching of calcitized dolomite rhombohedra. The regional dedolomitization was most likely brought about by calcium sulfate solutions reacting with dolomites. The source of sulfate solutions is the dissolved anhydrite deposits of the Arab–Hith Formations, sometime before their erosion, and it takes place at or near an exposed surface. The Hanifa Formation shows various diagenetic features. These include dolomitization, dedolomitization, micritization, cementation, and recrystallization. Most of the examined samples of the Hanifa carbonates are dolomitized and subsequently dedolomitized as evidenced by the presence of iron-coated dolomite rhombs partially or completely calcitized. Dolomite also occurs in the lime mudstone, wackestone, packstone, and grainstone facies, while leaching of wackestone and packstone and dedolomitization of dolomite and dolomitic limestone followed by recrystallization are common processes. 相似文献
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7.
云质岩储集层是准噶尔盆地乌—夏地区一套成因特殊的、富含油气的碳酸盐岩储集层。在分析乌—夏地区二叠系构造、沉积及火山活动等地质背景的基础上,根据风城组云质岩岩心宏观产状,将云质岩分为4种类型:波纹层状云质岩、团块状云质岩、丝絮状云质岩和星散状云质岩。镜下波纹层状云质岩晶粒细小,晶形差;团块状云质岩、丝絮状云质岩、星散状云质岩中白云石晶体以粉—细晶为主,普遍发育雾心亮边、环带交代残余结构。C、O同位素及微量元素等地化分析表明:白云岩化的成岩流体来自二叠系风城组半封闭湖湾的咸化沉积地层水以及下伏二叠系佳木河组、石炭系上涌的海相卤水。包裹体测温表明,蚀变方解石的形成温度为60～70℃,白云石的形成温度为85～105℃,白云石形成晚于蚀变方解石。波纹层状云质岩是准同生成因;团块状云质岩、丝絮状云质岩、星散状云质岩是后期成岩交代成因,交代的原岩是火山物质(凝灰岩)。成岩交代云质岩的成因机理是:火山凝灰物质中的火山玻璃容易发生水解蚀变,产物为蒙脱石、长石和石英;蒙脱石转化为伊利石、长石水解蚀变均可析出大量的Ca2+,结合CO2或CO32-形成蚀变产物方解石;方解石在富Mg2+流体交代下发生强烈白云岩化作用。 相似文献
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9.
白云石化是碳酸盐典型的成岩作用类型之一,中-下奥陶统鹰山组浅海碳酸盐岩是塔河地区重要的含油气储层,普遍发育多种类型的白云石化作用。本文针对塔河地区鹰山组灰岩中沿缝合线分布这一特定类型的白云石化进行了研究。岩石学基础上的阴极发光分析、86Sr/87Sr比值以及δ13C-δ18O 的研究表明,这种类型的白云石化发育于相对还原的浅埋藏成岩环境,孔隙中的残留海水是主要的白云石化流体来源,碳酸盐矿物(主要是高镁方解石)稳定化过程中释放的Mg2+ 可能是白云石化主要的物质来源,而埋藏过程中逐渐升高的温度一定程度上也促进了白云石化的发生。成岩流体及Mg2+ 有限的供给量限制了白云石化作用的整体规模。显微结构与岩石物性分析表明,该类白云石化对储层物性参数的绝对贡献相对有限,但可能成为小规模油气运移以及深部热流体活动的潜在通道。 相似文献
10.
刘英辉 《吉林大学学报(地球科学版)》2022,52(1):80-93
准噶尔盆地乌—夏地区二叠系风城组发育一套特殊的云质岩类,其沉积环境及成因复杂,目前仍存在较多争议。本文基于岩心观察（13口井）与系统取样测试分析（64个样品）,揭示了目标层位云质岩的岩石学和地球化学特征,探讨了不同类型云质岩的沉积环境及成因机制。研究结果表明：根据云质岩宏观结构特征,风城组可识别纹层状、星散状、丝絮状、团块状和不规则层状5种云质岩类型;高δ13CPDB值（平均4.0‰）、高古盐度值（平均13.0%）和深水沉积构造等特征表明目标层位沉积环境具有陆相低能、深水还原和咸水高矿化度等特点;纹层状云质岩为“高山深盆”盐湖卤水分层形成的准同生白云岩,团块状、不规则层状、丝絮状和星散状云质岩为埋藏交代白云岩。 相似文献
11.
Brick-like texture and radial rays in Triassic pisolites of Lombardy,Italy: A clue to distinguish ancient aragonitic pisolites 总被引：1，自引：0，他引：1
Triassic pisolites from the Calcare Rosso, Lombardy, Italy, were formed in a hypersaline vadose environment and now show alternating dolomite and calcite laminae. The calcite consists either of microsparite laminae with a brick-like fabric, or of a mass of mosaic crystals with the external form of square-ended rays.These features suggest that the original laminae and rays were aragonitic, like those of the Holocene supratidal pisolites of the Persian Gulf, which consist of alternating laminae of unoriented nannomicrite with Mg-rich mucilaginous material, and aragonitic fibers with radial orientation separated by mucilaginous films. It is suggested that the transformation to brick-like and ray textures passed through the following diagenetic path: (1) original formation of fibrous aragonite laminae; (2) local aggrading recrystallization of aragonite fibers to large square-ended rays during hypersaline phases; (3) dolomitization of Mg-rich mucilaginous nannomicrite laminae during hyposaline phases; (4) inversion of the aragonite fibers and rays to calcite on a piece-by piece basis that preserved the original textural details, when the pH or Mg/Ca ratio dropped.The brick-like and ray fabrics have not been found in laminae of continental freshwater pisolites because these were deposited as equant and stable crystals of low-Mg calcite. These textures consequently make it possible to establish the chemistry of the depositional and early diagenetic milieu for some ancient pisolitic rocks. 相似文献
12.
四川盆地西部中二叠统白云岩/石的主要结构类型——兼论其与川东北上二叠统—三叠系白云岩/石的差异 总被引：8，自引：2，他引：6
白云岩/石的结构在白云岩成因研究中具有重要意义。四川盆地西部中二叠统栖霞组的白云岩具有与盆地东北部上二叠统长兴组-三叠系不同的结构:盆地西部中二叠统栖霞组除存在一部分斑状晶白云岩以外,总体上缺乏原始结构保存的白云岩,白云石具有特征的非平直晶面他形晶和鞍形晶,且晶体较大;盆地东北部上二叠统长兴组-三叠系非常发育原始结构保存的白云岩,结晶白云岩也以晶体较小的平直晶面自形晶-半自形晶为主。对碳酸盐岩中白云石含量的分布模式而言,盆地西部中二叠统栖霞组出现频率最高的是白云石含量40%~60%的过渡岩石类型,这是一种非经典的分布模式,而盆地东北部上二叠统长兴组-三叠系则缺乏这样的过渡岩石类型,出现频率最高的是白云石含量大于90%和小于10%的端元岩石类型,这是一种经典的分布模式。白云岩/石的结构特征的差异反映盆地西部中二叠统栖霞组白云岩较高的结晶温度、较低的流体Mg/Ca比值、较短的白云化作用持续时间和不彻底的回头白云化作用;盆地东北部上二叠统长兴组-三叠系则主要是相对低温的,高Mg/Ca比值海源流体的彻底白云化作用。 相似文献
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根据岩心及薄片观察,按照矿物晶体的大小、形状以及自形程度的差异,将塔里木盆地中央隆起中部中下奥陶统碳酸盐岩地层中的白云石分为6种类型,包括泥微晶白云石、粉—细晶自形—半自形漂浮状白云石、粉—细晶半自行—他形白云石、粉—细晶自形(环带)白云石、细—粗晶他形白云石、粗晶鞍形白云石。综合不同类型白云石的结构特征、碳氧锶同位素值、阴极发光等特征,认为中下奥陶统白云石主要由三种成岩作用形成:泥微晶白云石主要是在准同生期由回流白云石化形成;大部分粉—粗晶白云石是在埋藏期由埋藏白云石化形成,其中浅埋藏期是大规模白云石化的阶段;粗晶鞍形白云石主要由与高温热液活动相关的热液白云石化形成。 相似文献
14.
Composite magnetic anisotropy fabrics: experiments, numerical models and implications for the quantification of rock fabrics 总被引：2，自引：0，他引：2
Magnetic fabrics from rocks with multiple mineral-preferred orientations may have anisotropy ellipsoids whose shape and orientation arise from the addition of two or more component fabrics. Our numerical models and experiments demonstrate that such composite magnetic fabrics do not directly reflect the shapes and/or orientations of the individual mineral fabrics and we provide criteria for the recognition and interpretation of composite fabrics in natural rocks. These criteria include:
1. (1) the orientation of the maximum susceptibility axis is located at the intersection of two planar fabrics, and
2. (2) the shape of the susceptibility ellipsoid changes from oblate to prolate and the degree of anisotropy decreases, as the relative intensity of two planar component fabrics becomes equal and as the angle between the planar fabrics increases.
Composite magnetic fabrics are observed in the shales and slates of the Martinsburg Formation, Lehigh Gap, Pennsylvania. Modeling of the AMS (anisotropy of magnetic susceptibility) and ARMA (anhysteretic remanent magnetization anisotropy) behavior constrains the relative degree of anisotropy of the bedding-parallel and cleavage-parallel fabrics. In particular, ARMA model results allow a good estimate of magnetite fabric strength.
We conclude that, in the presence of composite magnetic fabrics, quantitative measures of finite strain in deformed rocks are limited by the ability to accurately determine the degree of anisotropy and relative susceptibility of each component fabric. Such determinations require knowledge of the mineral(s) that are responsible for the measured magnetic fabric and their behavior during deformation. 相似文献
15.
二连盆地下白垩统发育一套陆源碎屑成分和碳酸盐矿物组成的混合沉积,且近年来在其中发现大量油气显示,但目前对这套混合沉积的研究程度较低。通过岩心观察、薄片鉴定、测井等方法,对巴音都兰、阿南和额仁淖尔等多个重点凹陷内云质岩的岩石学特征、分布特征等进行研究,认为：云质岩分布主要受母源区岩性控制,为典型的母源混合类型;湖盆演化类型不同导致沉积相发育的差异性,进而决定云质岩纵向分布;火山玻璃脱玻化为埋藏白云化作用提供大量Mg2 +、Fe2 +离子,导致白云石中铁含量高;古气候对云质岩分布的影响较弱。 相似文献
16.
WOLFGANG BLENDINGER 《Sedimentology》1991,38(2):223-242
Norian crinoidal/brachiopod limestones and cephalopod limestones of the Hallstatt-type occur as blocks in a Hettangian(?) calcareous breccia of the Haliw Formation in the Oman Mountains. Crinoidal and brachiopod packstones, up to 12 m thick, prevail in the lower part of the sequence and were deposited on a substrate of Norian forereef breccia. The overlying cephalopod wackestones, up to 4.9 m thick, have a basal white bed followed by red limestones with abundant planar and scalloped, corroded surfaces and local stromatolites. Upward, red, nodular wackestones and, finally, slumped grey wackestones follow. The analysis of geopetal fabrics in orientated samples shows that bedding of these facies is, in fact, inclined bedding. Inclinations varied between 15 and 29°. In addition, the restored dip directions demonstrate rotation, indicating deposition on a gliding block. The preferred orientation of orthoconic cephalopods and imbrication of discoidal ammonoids coincide with the dip direction measured from geopetal fabrics. Such features, generally interpreted as current-induced, are here interpreted as gravity-induced. The overall mud-supported rock fabric thus indicates deposition under very low-energy conditions. The common mud-supported texture of the rocks contrasts with evidence for current activity found in the scalloped surfaces and shell lags, particularly in the crinoidal/brachiopod facies and the lower, stratigraphically condensed, cephalopod limestones. This indicates that deposition of lime mud alternated with periods of elevated current strength. A comparison of the Hallstatt-type limestones and current-influenced sediments on the northern slope of the Little Bahama Bank suggests that condensed sequences of the Hallstatt-type are restricted to relatively shallow depths with strong fluctuation of contour-following currents undersaturated with respect to aragonite along carbonate shelf margins facing the open ocean. On steep slopes, sediment bypassing may be an additional factor for stratigraphic condensation. 相似文献
17.
P. Yu. Petrov 《Lithology and Mineral Resources》2016,51(4):290-309
Structures and textures of the peloidal wackestones, as well as size, shape, and composition of peloidal grains, from the Mesoproterozoic (Middle Riphean) Sukhaya Tunguska carbonate platform in the Turukhansk Uplift (Siberia) are considered. It is shown that these grains formed in the course of diagenesis were closely associated with the microsparitic replacement and the formation of molar tooth (MT) structures. Diagenetic transformations of rocks were related to the activity of anaerobic microbial communities inside the buried carbonate silt layers. The microbial activity during diagenesis was governed by the carbonate sediment composition and conservation mechanism of the high-molecular organic matter of primary producers therein, since this organic matter was the nutritious substrate for the primary anaerobe communities. 相似文献
18.
贵州中三叠世碳酸盐台地边缘的“堤礁”向来受到人们的关注,并成为研究的热点。当前对台地边缘沉积的性质存在着不同的观点。某些人认为这些沉积是在浅水和拢动环境下形成的滩相沉积;而另外一些研究者则仍坚持它们代表典型的礁相沉积,因为它含有丰富的造型生物,如六射珊瑚、苔藓虫、钙质海绵和龙介类等。在贵州中部关岭县扒子场出露了一套巨厚的和属于台地边缘的中三叠统。扒子场在关岭县城的东南,直距约22km。三叠系中下统沿着公路断面连续出露。中统包括安尼阶的坡段组及拉丁阶的垄头组和竹杆坡组。坡段组主要由砂砾屑－生屑颗粒岩组成,约占全剖面的2／3。它们形成于水流激荡的滩相环境。其他岩石为骨屑－球粒粒泥岩和泥粒岩,约占全剖面的1／3。根据该组的岩石结构、沉积构造和生物组分,坡段组代表由砂砾屑、生屑组成的粒屑滩,而非生物礁相沉积。仅在底部或下部出现少量的Tubiphytes-蓝细菌造礁骨架,组成局部的礁丘。 相似文献
19.
中韩第五次《东北亚地壳演化》学术研讨会在北京举行 总被引：2，自引：0，他引：2
新疆天山东部广泛发育晚石炭世碳酸盐岩隆。这些岩隆主要为生物丘,少数为生物滩及与岩隆有关的生物层,其中生物丘含大量灰泥和内碎屑。基本岩石类型为泥粒状灰岩、粒泥状灰岩、粒泥状－泥粒状灰岩,少量岩石类型包括颗粒岩、骨架岩和障积岩。成岩作用是碳酸盐岩隆发展演化的重要阶段和过程,在生物丘内,已经识别出四种重要的胶结物,即球粒泥晶、纤状方解石、放射轴状方解石和粒状方解石。尽管缺失典型的造礁生物,但通过岩石类型研究和微相分析,认为碳酸盐岩隆的形成主要取决于生物作用及古环境格局。本区碳酸盐岩隆可以同欧洲瓦尔索坦的岩隆对比 相似文献
20.
Multiphase dolomitization of deeply buried Cambrian petroleum reservoirs,Tarim Basin,north‐west China 
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下载免费PDF全文 Lei Jiang Chunfang Cai Richard H. Worden Stephen F. Crowley Lianqi Jia Ke Zhang Ian J. Duncan 《Sedimentology》2016,63(7):2130-2157
Cambrian dolostone reservoirs in the Tarim Basin, China, have significant potential for future discoveries of petroleum, although exploration and production planning is hampered by limited understanding of the occurrence and distribution of dolomite in such ancient rocks buried to nearly 8 km. The study herein accessed new drill core samples which provide an opportunity to understand the dolomitization process in deep basins and its impact on Cambrian carbonate reservoirs. This study documents the origin of the dolostone reservoirs using a combination of petrology, fluid‐inclusion microthermometry, and stable and radiogenic‐isotopes of outcrop and core samples. An initial microbial dolomitization event occurred in restricted lagoon environments and is characterized by depleted δ13C values. Dolomicrite from lagoonal and sabkha facies, some fabric‐retentive dolomite and fabric‐obliterative dolomite in the peloidal shoal and reef facies show the highest δ18O values. These dolomites represent relatively early reflux dolomitization. The local occurrence of K‐feldspar in dolomicrite indicates that some radiogenic strontium was contributed via terrigenous input. Most fabric‐retentive dolomite may have precipitated from seawater at slightly elevated temperatures, suggested by petrological and isotopic data. Most fabric‐obliterative dolomite, and medium to coarse dolomite cement, formed between 90°C and 130°C from marine evaporitic brine. Saddle dolomite formed by hydrothermal dolomitization at temperatures up to 170°C, and involved the mixing of connate brines with Sr‐ enriched hydrothermal fluids. Intercrystalline, moldic, and breccia porosities are due to the early stages of dolomitization. Macroscopic, intergranular, vuggy, fracture and dissolution porosity are due to burial‐related dissolution and regional hydrothermal events. This work has shown that old (for example, Cambrian or even Precambrian) sucrosic dolomite with associated anhydrite, buried to as much as 8000 m, can still have a high potential for hosting substantial hydrocarbon resources and should be globally targeted for future exploration. 相似文献