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1.
湖北大冶铁山地区缝合线三维形态模拟及其成因分析   总被引:1,自引:0,他引:1  
广泛发育于碳酸盐岩中的缝合线构造可以用来分析构造应力方位、计算岩层的有限应变和恢复原始地层厚度;同时,缝合线可以是石油、天然气和地下水的储积场所和运移通道。湖北大冶铁山地区发育有大量的缝合线构造。通过影像云纹法和GIS技术恢复了采自该地区的数枚缝合线标本的三维数字形态。利用该模型对缝合线的尺度、坡角、粗糙度、谷底点分布、二维剖面形态和压溶量等进行了定量分析,完善了缝合线的几何形态学研究并在此基础上对其成因进行了解释,认为铁山地区的缝合线主要由成岩压实作用和压溶作用形成,缝合线在从初始到各种复杂形态的发展过程中主要受两个因素控制:一是岩石的力学性质;二是由主压应力引起的局部应力集中而产生的溶解释放。   相似文献   

2.
传统观点认为,碳酸盐岩中的缝合线是在岩石负载或构造应力作用下压溶形成的,是一种化学压实作用的产物。对缝合线进行综合研究,发现其具有“四性特征”,即完整性、亲烃性、排孔性及胀裂汇聚性。综合以上“四性”认为,缝合线主要是岩石在负重或构造应力作用下烃类(或泥质)使岩石发生胀裂形成的一种锯齿状裂缝,是烃类(或泥质)开辟的排烃通道,压溶作用对缝合线的贡献还有待研究。与碳酸盐岩相比,泥岩不发育缝合线,主要在于泥岩优势孔隙半径较大,烃类可以通过微孔以渗透方式向外排放,不需要形成缝合线。通过缝合线形成机理探讨,查明了碳酸盐岩与泥岩排烃方式的区别,进而对碳酸盐岩与泥岩封盖性进行对比。  相似文献   

3.
压溶作用产生的缝合线是烃富集的场所及初次运移的通道。碳酸盐岩烃源岩压溶过程,随着地层厚度和体积的减小,未熟和低熟油气会伴随孔隙流体一同排出。根据碳酸盐岩埋藏与压溶机理,提出了压溶的碳酸盐岩缝合线或溶解缝厚度恢复及其古厚度恢复的数学模型,同时结合碳酸盐岩基质和缝合线孔度随深度的变化曲线建立了定量计算碳酸盐烃源岩压溶排烃量的数学模型。上述数学模型的关键是确定压溶作用开始和结束的深度和时间,缝合线的厚度  相似文献   

4.
据我国许多地区石灰岩中缝合线的野外观察和采样制片显微镜下观察鉴定的结果,论述了缝合线的特征。应用热力学原理分析研究了缝合线成因机理,并计算出缝合线形成的最小埋深、最低临界压力和最高临界温度。证明了缝合线压溶说成因论是正确的。得出缝合线的形成会使岩石的孔隙度和渗透率降低,储集层的物性变差等结论。研究缝合线有重要的理论和实际意义。  相似文献   

5.
缝合线构造是古代碳酸盐岩中常见的一种沉积构造现象,属原生微构造类型。它在剖面中一般呈锯齿状曲线,状如动物头盖骨中的接合缝,平面上呈一个起伏不平的面。通常认为缝合线为压溶作用所形成,即在上覆岩层的静压力下,碳酸盐岩层产生不均匀的溶解而成。它的形成与岩石的成分、结构和环境有关。根据本区缝合线的发育特征,可将缝合线分为原生和次生两种成因类型:(1)原生  相似文献   

6.
压溶角砾岩出现征构造带的较深部位并与构造角砾岩伴生,它是碳酸盐岩石构造破碎的一种特殊型式。压溶角砾岩由不同方向的缝合线发育而成,胶结物主要是碳酸盐岩的不溶残余物。碳酸盐岩中的铀含量主要与不溶残余物有关。在压溶作用发育过程中,岩层中的铀被活化、渗滤,在有利的物化环境中被炭、泥等吸附而富集,也可与其它成矿作用叠加而成矿。  相似文献   

7.
王化锐 《地球学报》1991,12(1):35-50
本文运用显微构造分析方法,讨论成岩期后铀矿化活动的构造环境。文中指出:矿化活动的首要条件是构造扰动;铀源质量改善和其后的叠加富集是矿化过程中的两次重要事件;吸附着铀的炭经构造重结晶作用从晶体中排出,从而改善了铀源质量;获释的炭和铀沿张性、张扭性裂隙聚集形成矿体;构造的作用在于提供了改变铀源的动力条件和矿化富集的空间场所。 方解石变形双晶、压溶缝合线等显微构造分析结果,一致表明区内引起变形的主应力近于水平。由压溶和重结晶前后矿物总表面积的变化推算的矿物表面能的变化为0.133J/cm3,以衡量应力强度。由动态重结晶颗粒粒度法估算的贮存着矿体的断裂的差异应力(σ_1-σ_3)为24—51MPa,且铀量随差异应力的增大而增加。  相似文献   

8.
<正> 压溶作用是碳酸盐沉积物在成岩作用阶段始终都存在的极为重要的作用。碳酸盐沉积物(岩)经压溶作用所产生的组构,最常见的是缝合线,此外还有羽状晶(压力影)、“角砾”、“瘤状”、“层纹”等构造。本文拟通过对陕南—川北地区二叠—三叠系碳酸盐岩中压溶组构的野外观察和室内鉴定工作,对压溶作用在碳酸盐岩中所产生的一些组构特征及其与原生组构的区别加以综合论述。  相似文献   

9.
大梁子铅锌矿是川西南矿集区典型的大型矿床之一, 矿床(体)的空间展布严格受F15主控断裂及其次级构造控制, 它们为成矿流体运移和矿质沉淀提供了有利场所。针对该矿床成矿构造体系、F15主控断裂及其控矿作用的核心问题, 应用矿田地质力学理论与方法, 通过主控断裂几何学、运动学、力学、构造岩、构造期次等方面的解析, 结合地球化学研究, 认为F15主控断裂在成矿期具有导矿和容矿的特征, 主走滑-断褶构造组合样式(负花状构造)是该矿床的主要构造组合样式。F15主控断裂主要表现出2期构造活动: 早期(印支中晚期—燕山早期)因NW—SE向主压应力作用, 形成右行扭张-张扭性构造, 晚期(燕山中—晚期)因NE—SW向主压应力作用, 断层转化为左行扭性-扭压性, 右行扭张-张扭性及派生出的一系列NWW—NW向张性断裂、NE向压扭性断裂及NE向SW倾伏主背斜组合而成的NE向构造带, 为主要成矿构造体系。与铅锌成矿有关的Zn-Pb-Cd-Sb-Hg-Ag-As等元素组合和与深部流体有关的Mo-Tl等成矿元素组合均表现为明显富集现象; 成矿流体沿F15导矿构造"贯入", 沿次级NWW—NW向断裂和NE向SW倾伏主背斜、层间断裂构造系统发生"贯入"-交代作用, 形成矿床。该研究不仅对大梁子铅锌矿深部及外围找矿具有实际意义, 对于川西南铅锌多金属矿集区构造控矿规律研究也具有科学价值。  相似文献   

10.
正缝合线是在地层上覆压力的作用下,接触的沉积物颗粒间发生选择性溶解而形成的裂缝,可形成于从沉积成岩到深埋的各个阶段。缝合线可以发育于各种岩性中,在碳酸盐岩储层中发育十分普遍,是碳酸盐岩储层中常见的地质构造。前人对缝合线的研究主要集中在成因、缝合线分类、物质组成、缝合线几何形状的定量化分析、地层压溶损失以及对于油气地质的意义等方面,极少对控制缝合线分  相似文献   

11.
Stylolites are rough surfaces, formed by localized rock dissolution, and prevalent in carbonates and other sedimentary rocks. Their impact on porosity and permeability, and capacity to accommodate compactive strain, are well documented. This paper presents a meso-scale field study on sedimentary stylolites in carbonates, characterizing large-scale distributions of stylolites, including measurements conducted on longer than kilometer-long stylolites. Our field study suggests that on large scales connections between stylolites become important. Since connectivity, and also lack of connectivity, are expected to play a significant role in strain accommodation and hydraulic rock properties, we suggest that large-scale analysis may require a new characterization scheme for “stylolite populations”, based on their connectivity. We therefore divide sedimentary stylolite populations into three end-member types, which are correlated with the three possibilities for percolation of such systems: isolated stylolites (with zero percolation/connectivity), long-parallel stylolites (with 2-dimensional percolation/connectivity), and interconnected stylolite networks (with 3-dimensional percolation/connectivity). New statistical parameters and measures are devised and used to quantitatively characterize the different population types. Schematic mechanistic models are then offered to explain the evolution of the three end-member connectivity-classes. In addition we discuss the effect on fluid flow of the different population types.  相似文献   

12.
13.
松辽盆地北部深层的酸性火山岩中广泛发育缝合线构造。缝合线可分为两类,一类常发育于岩性差异面或流纹面等界面处,产状受岩性界面或流纹面控制;另一类则与岩性界面无关,产状与构造裂缝相似。扫描电镜(SEM)的观察表明,缝合线的三维形态复杂多变,缝合柱的侧面具有显微滑痕特征。电子探针分析表明,火山岩缝合线中主要富集Fe,Al,K等元素,亏损Si和Na等元素,反映其主要物质组成为铁的氧化物、高岭石和钾盐等,局部含少量的碳酸盐岩。综合分析认为火山岩中的缝合线属后生成岩作用阶段的产物,与长英质矿物的溶解或蚀变有关,是本区火山岩岩性、地温场、流体场及应力场等因素共同作用的结果。  相似文献   

14.
This paper addresses the diagenesis of carbonate conglomerates in that it assesses the potential of conglomerates in refining the paragenetic history in complex structural areas, such as the Albanian foreland fold‐and‐thrust belt. Of major interest are stylolites (burial and tectonic) which are restricted to conglomerate fragments or which crosscut the conglomerate matrix. Based on the inferred age of stylolite development in relation to burial, uplift and tectonic history, and the Lower to Middle Miocene age of the conglomerates, the succession of diagenetic events was subdivided into several stages. The Poçem polymict transgressive carbonate conglomerate (Kremenara anticline, central Albania) was deposited in a shallow marine environment. These conglomerates are covered by intertidal rhodolithic packstones–grainstones. The stable‐isotope signature of these packstones–grainstones (δ18OV‐PDB = −1·0 to +0·7‰; δ13C = +1·0 to +1·4‰) plots is within the range of marine Early and Middle Miocene values. Shortly after deposition of the conglomerates, micritization, geopetal infill and acicular calcite cementation took place. A first calcite vein generation is interpreted as having formed from a Messinian brine during shallow burial. Burial stylolites developed during further burial in the Pliocene. These stylolites serve as an important diagenetic time marker. The post‐burial stylolite meteoric calcite vein cement probably precipitated during the following telogenetic stage. Karstification and calcite concretion precipitiation pre‐date overturning of the western limb of the anticline. Reopening of subvertical fractures and tectonic stylolites in the western limb of the Kremenara anticline, followed by oil migration, represents one of the latest diagenetic events. These fractures and stylolites provide major pathways for hydrocarbon production.  相似文献   

15.
吕洪波 《地质论评》2009,55(4):473-483
笔者在山东省淄博市博山区中奥陶统马家沟群白云岩和上石炭统本溪组石灰岩中识别出垂直缝合线。垂直缝合线都借助于平面X剪节理发育,缝合面上的“牙齿”与缝合面本身多呈斜交状态,其延伸方向代表着变形期最大主压应力轴(σ1)方向。根据垂直缝合面“牙齿”的突出方向判别:以山东博山地区为代表的华北东部地区在古生代中期和末期先后两次受到NNE—SSW方向的水平挤压作用。其中第一次挤压事件与遍布华北东部的中奥陶统—上石炭统(C2—O2)平行不整合抬升相关,而第二次则与华北东部古生代末期的褶皱隆起相联系。本文的研究为垂直缝合线在盆地构造演化研究中的应用提供了良好的研究实例。  相似文献   

16.
柳广弟  高岗 《沉积学报》1999,17(3):482-485
通过碳酸盐岩地层中的纯碳酸盐岩、缝合线缝隙物和泥质条带有机质含量和残留烃量分析表明,碳酸盐岩地层中不同的组成部分之间有机质的分布是不均匀的,其中缝合线缝隙物和泥质条带具有高的TOC值和较低的S1/ TOC 值,而纯碳酸盐岩TOC值则很低,但其S1/ TOC 却很高。这说明缝合线缝隙物和泥质条带发生了明显的排烃作用,而纯碳酸盐岩排烃作用不明显。因此可以认为高有机质丰度的缝合线缝隙物和泥质条带是碳酸盐岩地层烃源的主要贡献者。压溶作用对碳酸盐岩的排烃起重要作用。  相似文献   

17.
The origin of quartz cement in sandstones can be attributed to supplies (1) from the surrounding shales, and (2) to a lower degree from dissolution of quartz on stylolites within the sandstones. A supply from the surrounding shales, which has been shown by the porosity decrease near the upper and lower surfaces of different sandstones (Füchtbauer, 1974), can be explained by the following observations in Upper Triassic and Middle Jurassic sandstones and siltstones of Northern Germany as well as in concretions of Devonian to Upper Cretaceous age from different localities:
  1. Quartz grains in silt layers are flattened by dissolution compared with quartz grains of the same size in the adjacent sandstones, the amount of shrinking being about 35 percent (fig. 1).
  2. Concretions prevent the enclosed insoluble residues from diagenesis. The main difference between the concretions and the adjacent shale of 31 occurrences examined is the quartz content, which is by 10–50 percent lower in the adjacent shale, due to diagenetical dissolution (fig. 2).
It is suggested that the dissolved silica was brought to the sandstones by the compaction stream of interstitial water percolating through the rock sequence, and that the sandstones acted as sinks triggering the dissolution. Only a small amount of silica, about 10 percent of the silica from dissolved quartz, is provided by the transition montmorillonite — illite. Both sources together would be able to explain the precipitation of 20 percent quartz cement in a sequence composed of 1/3 sandstones and 2/3 shales. In the sandstones mentioned above stylolites can be observed (fig. 3), the amplitudes of which increase from 0,5–1 mm to 2–5 mm with increasing depth, between 1300 and 2600 metres. The real amount of dissolution on each stylolite — about 4 mm — has been calculated using large mica which were collected by the stylolites from the adjacent sandstone. Using this figure, the decrease of porosity in the sandstones shown in fig. 4 can be quantitatively explained by the frequency of stylolite intercalations. It is suggested that this process, which was due to local diffusion, occurred late in diagenesis, when the compaction stream was already insufficient to move large quantities of silica.  相似文献   

18.
The Late Jurassic-early Senonian Cehennemdere Formation extending in an E-W direction in a wide area at the south of the Bolkar Mountains (Central Taurides, Turkey) is composed of platform carbonates. The formation was deposited in an environment that was being transformed from a shallow carbonate platform to an open shelf and a continental slope, and was buried until late Paleocene uplift. The formation, with a thickness of about 360 m, was chiefly developed as textures consisting of mudstone and wackestone and has been commonly dolomitized. Based on petrographic and geochemical properties, four types of replacement dolomites and two types of dolomite cements were distinguished. Replacement dolomite (RD), which is cut by low-amplitude stylolites developed as (1) fine crystalline planar-s dolomite (RD1); (2) medium crystalline planar-s dolomite (RD2); (3) medium-coarse crystalline planar-e dolomite (RD3) and; (4) coarse crystalline planar-s (e) dolomite (RD4). Two types of dolomite cements (CD) observed in low abundance and overlie low-amplitude stylolites: (1) coarse crystalline dolomite cement (CD1) filling dissolution voids and fractures in RD1 dolomites, and; (2) rim dolomite cement (CD2) that commonly develops on the space-facing surfaces of RD4 dolomite. Replacement dolomites are non-stoichiometric (Ca54–59Mg41–46), have similar geochemical properties, and are generally dull red/non luminescent in appearance. Replacement dolomite is represented by δ18O values from −4.5 to −0.5‰ VPDB, δ13C values of −0.7 to 2.7‰ VPDB, and 87Sr/86Sr ratios ranging from 0.707178 to 0.707692. Petrographic and geochemical data indicate that replacement dolomite (particularly RD2, RD3, and RD4 dolomite) was formed at shallow-intermediate burial depths during the Late Jurassic-Early Cretaceous, from seawater and/or from slightly modified seawater. The replacement dolomite (RD) was then recrystallized at increased burial depths and temperatures. Dolomite cements are similar to replacement dolomites in that they are non-stoichiometric (Ca55Mg45) and have similar trace element compositions. CD1 dolomite, which cuts low-amplitude stylolites, was formed during intermediate to deep burial following stylolite development. CD2 dolomite was precipitated in intercrystal pores in association with RD4 dolomite. Remaining pore space was filled with bitumen.  相似文献   

19.
The impact of CO2 sequestration on the host formation is an issue occurring over geologic time. Laboratory tests can provide important results to investigate this matter but have limitations due to a relatively short timeline. Based on literature review and core sample observation, naturally occurred geological phenomena, stylolites are studied in this paper for understanding CO2 sequestration in deep carbonate formations. Stylolites are distinctive and pervasive structures in carbonates that are related to water-assisted pressure solution. Pressure solution involving stylolitization is thought to be the main mechanism of compaction and cementation for many carbonates. In parallel, CO2 sequestration in carbonate formation involves extensive chemical reactions among water, CO2 and rock matrix, favoring chemical compaction as a consequence. An analogue between stylolites and CO2 sequestration induced formation heterogeneity exists in the sense of chemical compaction, as both pressure solution in stylolites and CO2 enriched solution in CO2 sequestration in carbonate formations may all introduce abnormal porous regions. The shear and/or tension fractures associated with stylolites zones may develop vertically or sub-vertically; all these give us alert for long-term safety of CO2 sequestration. Thus a study of stylolites will help to understand the CO2 sequestration in deep carbonate formation in the long run.  相似文献   

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