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1.
一条特殊的超浅成脆—韧性剪切带：湘西白沙镇含油瘤状灰岩带 总被引：7，自引：0，他引：7
湘西泸阳县白沙镇西发育了一条特殊的脆韧性剪切带。该剪切带中除了发育了许多脆性变形外，还发育了许多韧性剪切的标志：如Ｓ－Ｃ组构，方解石鱼、核幔构造、方解石ｅ双晶、方解石波状消光、钙质糜棱岩条带以及（光学）各向异性体。经研究发现该剪切带的形成深度不超过３．０ｋｍ，其中的大量石油也与脆韧性剪切作用有一定关系。 相似文献
2.
煤层气的形成和赋存与煤变质的古地温场条件密切相关。本文利用镜质组反射率Ro,max反演煤变质的古地温场,从而揭示出我国晚古生代煤层气的生成和赋存,与我国板块运动及其对区域地温场的控制作用密切相关。 相似文献
3.
结构面力学性质的定量鉴定 总被引：8，自引：0，他引：8
变形带力学性质的鉴定是地质力学研究中的先行基础步骤.近来出现一些新的概念和方法,可用以定量表征变形带的力学性质.天然变形带通常是一般剪切作用的产物,是纯剪切(共轴缩短或伸展)和简单剪切的组合.为了定量说明两者间的相对贡献,提出了运动学涡度(Wk)这一物理量,并简单地定义为cos υ.υ是主变形面内两特征方向间的夹角.纯剪切的υ=90°,Wk=0;简单剪切的υ=0°,Wk=1.一般剪切的υ介于0°和90°之间,Wk为0到1.运动学涡度符号的正负分别代表变形带的减薄和增厚.υ可通过极摩尔圆法求出.主压应力(σ1)方向与Wk的关系为Wk=sin2ξ.ξ是σ1与变形带法线间的夹角.因此,可用以确定变形带的Wk和力学性质.根据最大有效力矩准则,韧性变形带与主压应力(σ1)方向间的夹角为55°,可用以确定古应力轴的方向,并可能确定变形时差应力的大小. 相似文献
4.
吉尔吉斯斯坦北天山构造带的矿床学数据缺乏,制约了天山造山带境内外成矿对比。布丘克金矿床位于吉尔吉斯斯坦北天山构造带中部。金矿体为石英复脉,呈带状发育于NWW向韧性剪切带中。矿体倾向SSW,倾角60°～70°,赋矿围岩主要为侵入于早古生代变质碎屑杂岩中的正长斑岩。布丘克金矿床成矿期石英流体包裹体观察、石英H-O同位素、硫化物S同位素测试结果显示,布丘克金矿床石英脉中包裹体大小集中在2～10μm之间,类型以H2O-CO2型、富CO2型、水溶液型包裹体为主,成分以富CO2、含CH4为特征。成矿流体具有中温(200～320℃)、低盐度(3%～7%NaCleqv)特征;石英δDV-SMOW值介于-108.1‰～-90.2‰之间,δ18O流体值介于4.86‰～9.26‰之间;黄铁矿δ34S分布在0‰左右(-0.9‰～1.6‰)。综合本文数据、矿床地质特征、区域地质资料,本文认为布丘... 相似文献
5.
西林河脆-韧性剪切带是区域上富尔河-古洞河岩石圈深断裂带的重要组成部分,总体走向330°,由东部(F1,F2,F3)、中部(F4,F5)和西部(F6)3条脆-韧性剪切断层带组成。东部带以脆性变形为主,延长约4km;中部带除脆性变形外兼有塑性变形,延长约5km;西部带以塑性变形为主,总延长5.5km。构造岩比较发育,分为脆性变形构造岩系列和塑性变形构造岩系列。构造岩的变形和退变作用同时进行。西林河脆-韧性剪切带反映了西林河金矿的成矿时代为燕山期,是金成矿的导矿和容矿构造。本着就矿找矿的原则,根据成矿地质条件,在已有的6个矿体的延伸方向进行追索找矿;根据边缘成矿作用观点,可在矿区内太古宙灰色片麻岩与元古宙浅变质岩的接触带进行找矿。确立了6条找矿标志。 相似文献
6.
7.
基于散粒体微观力学理论,忽略颗粒转动引起的相对位移,考虑颗粒接触的组构各向异性,根据宏微观能量守恒推导得到了散体材料各向异性微形态本构关系,进而通过单位接触方向积分的递推公式推导出了各向异性本构张量表达式;在此基础上,根据哈密顿原理得到了各向异性散体材料的运动平衡方程和边界条件,从而求得了平面波在各向异性散粒体中的传播规律和频散关系,最后对波的频散关系和频率带隙进行了详细的参数分析。研究表明：该模型预测了散体中包含3类12种位移波：3种纵波、6种横波和3种平面内横向剪切波;横观各向同性条件下,接触各向异性参数a20越大,纵波和横波的频率越大,而平面内横向剪切波的频率越小;正交各向异性条件下,随着接触各向异性参数a22的增大,与2方向运动相关的横波频率增大,而与3方向运动相关的横波频率则减小;但a22的变化对纵波频率影响很小。材料各向异性程度对横波带宽影响不大,但对纵波带宽影响较大：a20的增大使得声?光学波间的带宽减小,而光学波间的带宽增大,当a20>0.84时,声?光学波间的带隙消失;但是a22的增大则使得声?光学波间的带宽增大,而光学波间的带宽减小。退化为各向同性模型后,预测3类波的频散曲线与其他各向同性模型的结果基本一致。 相似文献
8.
襄樊——广济断裂西段的三里岗——三阳地区出露有构造混杂岩,以含蛇绿岩残块为特征,经历了复杂的构造变形和演化过程。不同区段的构造解析与对比表明,中生代以来该构造混杂岩带主要遭受了4期变形构造的叠加改造:1)高温塑性变形(D1),表现为蛇绿岩残块内部具网状强应变带和透镜状弱应变域相互交织的构造变形样式,强应变带形成以镁铁质糜棱岩为特征的高温韧性剪切带,显示深层次构造变形特征;2)逆冲推覆变形(D2),构造混杂岩带发育叠瓦状逆冲推覆构造和双冲构造,南界韧性剪切带是构造混杂岩带整体运移的主推覆面,发育长英质糜棱岩,形成于中等构造层次,岩石中发育镁铁质糜棱岩糜棱面理的褶皱构造,显示陆内逆冲推覆对先期高温塑性变形构造的叠加改造;3)韧脆性右行平移剪切(D3),形成构造混杂岩带内部浅层次构造变形,构造混杂岩带南侧的花山群钙质片岩揉皱变形,形成枢纽近直立的不对称褶皱,指示右行平移剪切变形;4)伸展正断层(D4),主要发育于构造混杂岩带北侧,呈NW——SE向展布,控制晚白垩世断陷盆地的形成与沉积充填。 相似文献
9.
巴特巴克布拉克铁矿床赋存于上志留-下泥盆统康布铁堡组变质火山-沉积岩系中, 近矿围岩为石榴子石矽卡岩、角闪斜长变粒岩和浅粒岩。矿体总体顺层分布, 呈似层状、透镜状及不规则状, 空间上与矽卡岩密切相关。流体包裹体研究表明, 矽卡岩阶段形成的石榴子石中发育纯气体包裹体、气体包裹体、液体包裹体、含子矿物包裹体及熔融包裹体; 退化蚀变阶段发育液体包裹体和少量气体包裹体; 石英-硫化物阶段主要发育液体包裹体、含液体CO2的三相包裹体及少量纯气体包裹体、气体包裹体和含子矿物包裹体。矽卡岩阶段均一温度变化为217 ℃~499 ℃, 在255 ℃出现峰值, 盐度(NaCleq)变化为8.68%~22.65%; 退化蚀变阶段均一温度变化为181 ℃~432 ℃, 在225 ℃出现峰值, 盐度变化为12.85%~22.65%; 石英-硫化物阶段均一温度变化为140 ℃~482 ℃, 在155 ℃出现峰值, 盐度变化为0.18%~42.40%。石榴子石、石英和方解石的 δ18 OSMOW 变化为1.8‰~7.1‰, δ18ΟΗ2Ο为 -4.79‰~4.57‰, δDSMOW 为 -128‰~-84‰, 表明矽卡岩阶段成矿流体主要为岩浆水, 混合少量大气降水; 石英-硫化物阶段大气降水所占比例明显增加。方解石δ13 CV-PDB 变化为 -3.2‰~-2.0‰, 表明流体中的碳来自深部或地幔。 相似文献
10.
以层序地层学理论为指导,综合地震、测井、岩芯以及古生物等资料,对贝尔凹陷下白垩统层序格架下砂体的分布特征进行研究。研究表明:在三级层序格架下,不同沉积期沉积体系的空间展布和配置关系有明显差异,SQA层序为初始裂陷型层序,主要发育冲积扇、近岸水下扇等粗碎屑沉积体系;SQB～SQC层序为伸展裂陷型层序,发育近岸水下扇、湖底扇、扇三角洲和半深湖相等沉积体系;SQD～SQF层序为裂陷收敛型层序,发育三角洲、滨浅湖和半深湖以及河流、沼泽相等沉积体系。低位域砂体为岩性圈闭的形成提供有利条件,其时空展布主要受幕式构造运动及其产生的构造坡折带的类型和样式控制。在垂向上,构造坡折带类型控制不同类型低位域砂体的形成和分布,其中断崖型坡折带形成近岸水下扇,断阶型坡折带形成浊积扇以及断坡型坡折带形成扇三角洲砂体;在平面上,构造坡折带平面样式控制低位域砂体的空间展布特征,尤其是砂体的形态及规模受断层调节带控制。受同沉积断层组合样式的控制,平面上主要形成断弯型、断接型、断沟型以及交叉型等4种基本砂体分布类型以及断弯-交叉型、断弯-对接型、断弯-断沟型、对接-交叉型、对接-断沟型和交叉-断沟型等6种复合砂体分布类型。低位域砂体在洼槽区相互叠置、连片分布,为各类岩性-地层圈闭的形成创造条件。 相似文献
11.
A new maturity parameter determined on both oil and bitumen samples, the asphaltene Tmax, is proposed and discussed. This parameter could be very useful to address the maturity of the source rock. The asphaltene Tmax is measured by programmed Rock-Eval pyrolysis, using a modified temperature program. Some phases of the experimental procedure, such as the asphaltene preparation and the Rock-Eval measurement substratum choice, are crucial in order to achieve reliable data. Laboratory simulations were carried out in order to assess the possible effects of both primary and secondary migration on asphaltene Tmaxin the expelled oil: the original value of the asphaltene Tmax in the bitumen is not substantially modified and it is very close to that measured on kerogen. Examples of the determination of asphaltene Tmax on many samples, collected from different areas and with different organic matter composition, are given. Results show that Tmax values from oil asphaltenes are reasonable indicators of source rock maturity. 相似文献
12.
The role of shear strain in the graphitization of a high-volatile bituminous and an anthracitic coal
A ‘soft’ carbon-based high-volatile bituminous (Ro max=0.68%) coal and a ‘hard’ carbon-based Pennsylvania anthracite (Ro max=5.27%) were deformed in the steady state at high temperatures and pressures in a series of coaxial and simple shear deformation experiments designed to constrain the role of shear strain and strain energy in the graphitization process. Tests were carried out in a Griggs-t type solid (NaCl) medium apparatus at T=400–900°C, constant displacement rates of 10-5−10-6 s−1, at confining pressures of 0.6 GPa (coaxial) or 0.8 and 1.0 GPa (simple shear). Coaxial samples were shortened up to 50%, whereas shear strains up to 4.9 were attained in simple shear tests. Experiments lasted up to 118 h. Deformed, high-volatile bituminous coal was extensively coked and no correlation between strain and Ro max, bireflectance or coal texture was observed in any samples. With increasing temperature, Ro max and bireflectance increase in highly anisotropic, coarse mosaic units, but remain essentially constant in the fine granular mosaic, which becomes more abundant at higher temperatures. Graphite-like reflectances are observed locally only in highly reactive macerals and in pyrolytic carbon veins. The degree of molecular ordering attained in deformed bituminous coal samples appears to be determined by the heating-pressurization path rather than by subsequent deformation.Graphitization did not occur in coaxially deformed anthracite. Nonetheless, dramatic molecular ordering occurs at T>700°C, with average bireflectance values increasing from 1.68% at 700°C to 6.36% at 900°C. Anisotropy is greatest in zones of high strain at all temperatures. In anthracite samples deformed in simple shear over the 600–900°C range at 1.0 GPa, the average Ro max values increase up to 11.9%, whereas average bireflectance values increase up to 10.7%. Bireflectance increases with progressive bedding rotation and, thus, with increasing shear strain. Graphitization occurs in several anthracite samples deformed in simple shear at 900°C. X-ray diffraction and transmission electron microscopy of highly anisotropic material in one sample confirms the presence of graphite with d002=0.3363 nm. These data strongly suggest that shear strain, through its tendency to align basic structural units, is the factor responsible for the natural transformation of anthracite to graphite at temperatures far below the 2200°C required in hydrostatic heating experiments at ambient pressure. 相似文献
13.
J. Koch 《International Journal of Coal Geology》1997,33(4):301-316
Results of an organic petrographic study of the Kupferschiefer (Zechstein, Upper Permian) in northern Germany are presented. Because vitrinite occurs only sporadically in this black shale, the random reflectance (Rr) of a relatively high reflecting, vitrinite-like variety of bituminite was measured as a maturity parameter and the problems connected with this procedure were investigated.The main organic component is bituminite, generally with an abundance of more than 90%. Sporomorphs and algae are relatively scarce, inertinite is usually a trace component, and vitrinite is present only in some samples taken close to the coast of the Zechstein sea. Migrabitumen also occurs in small amounts in a few samples. The range of the bituminite reflectance values is often considerable and depends on rank, anisotropy, particle size, porosity, and shearing. Interpretation of the reflectance values is made difficult by differences of up to 0.4% Rr between layers within the Kupferschiefer. Hydrothermal alteration may also be present. The difference between the reflectance of the light and normal varieties of bituminite disappears between 0.9 and 1.2% Rr.Bituminite behaves in a way very similarly to vitrinite during coalification. Their reflectance is identical between 2 and 4% Rr. Below 2% Rr, the reflectance of bituminite is lower than that of vitrinite. Linear regression curves valid up to 4% Rr were calculated for Rmax versus Rr and for Rr versus Rmax. Taking certain limitations into consideration, bituminite reflectance may be used as a coalification parameter. 相似文献
14.
Rüdiger Lutz Birgit Gieren Andreas Lückge Heinz Wilkes Ralf Littke 《Organic Geochemistry》2000,31(12)
Investigation of sediment samples from Sites 1039 and 1040 (ODP Leg 170) drilled off the Nicoya peninsula (Costa Rica) by organic geochemical and organic petrological methods has revealed that subduction has only little influence on the composition of the sedimentary organic matter. Organic carbon contents reached 1.5% in the Pleistocene samples but Miocene and Pliocene sediments had an average organic carbon content of less than 0.5%. Organic carbon/sulfur ratios are generally below 2.8, reflecting an intense sulfate reduction in the uppermost sediments which was enhanced by sulfate supply both from sea water and deeper strata. Microscopical examinations indicate that the organic matter is mainly derived from marine sources. A small amount of terrigenous organic matter is, however, present as well according to n-alkane and fatty acid distributions. The alkenone unsaturation index U37k′ shows only a slight decrease during the Miocene and Pliocene, and stronger variations in the Pleistocene, probably indicating more stable sea surface temperatures during the Miocene and Pliocene. Variations in the Pleistocene can possibly be related to glacial/interglacial changes. 相似文献
15.
Immature vitrinite samples from a Miocene lignite seam of western Germany (H/C = 1.14, O/C = 0.41) and alginite concentrates from a Tasmanite deposit of Australia (H/C = 1.60, O/C = 0.10) were pyrolyzed in a stream of argon at heating rates of 0.1 and 2.0°C/min up to temperatures varying from 200 to 670°C. The solid maceral residues were subjected to elemental and microscopical analysis and studied by IR and 13C CP/MAS NMR spectroscopy with respect to structural modifications.The maximum pyrolytic weight loss amounts to 60% of the initial organic matter in the case of vitrinite and to 85% for alginite, the onset of degradation reactions being shifted to higher temperatures with increasing rate of heating. Both infrared and NMR spectra of the vitrinite samples indicate a rapid decomposition of the cellulose component upon heating whereas lignin related structures such as aromatic ether linkages remain remarkably stable. The main hydrocarbon release from vitrinite occurs at very early evolution stages (Tmax = 296°C, Rm = 0.20% at 0.1°C/min; Tmax = 337°C, Rm = 0.23 at 2.0°C/min). Hydrocarbon generation from alginite requires higher temperatures (Tmax = 388 and 438°C) and is completed within a distinctly narrower temperature range.The pronounced increase of vitrinite reflectance between 350 and 670°C seems to be associated with a rather time-consuming reorganization of the residual organic material. The concomitant growth of polyaromatic units is illustrated by the increasing intensity ratio of the aromatic ring stretching vibration bands at 1600 and 1500 cm−1. These reactions are moreover marked by increasing loss of phenolic oxygen and by increasing conversion of aliphatic carbon into fixed aromatic carbon. 相似文献
16.
Role of coal type and rank on methane sorption characteristics of Bowen Basin, Australia coals 总被引：5，自引：0，他引：5
The effect of coal composition, particularly the organic fraction, upon gas sorption has been investigated for Bowen Basin and Sydney Basin, Australia coals. Maceral composition influences on gas retention and release were investigated using isorank pairs of hand-picked bright and dull coal in the rank range of high volatile bituminous (0.78% Ro max) to anthracite (3.01% Ro max). Adsorption isotherm results of dry coals indicated that Langmuir volume (VL) for bright and dull coal types followed discrete, second-order polynomial trends with increasing rank. Bright coals had a minimum VL at 1.72% Ro max and dull coals had a minimum VL at 1.17% Ro max. At low rank, VL was greater in bright coal by about 10 cm3/g, but as rank increased, the bright and dull trends converged and crossed at 1.65% Ro max. At ranks higher than 1.65% Ro max, both bright and dull coals followed similar trends. These competing trends mean that the importance of maceral composition on VL varies according to rank. In high volatile bituminous coals, increases in vitrinite content are associated with increases in adsorption capacity. At ranks higher than medium to low volatile bituminous, changes in maceral composition may exert relatively little influence on adsorption capacity. The Langmuir pressure (PL) showed a strong relationship of decreasing PL with increasing rank, which was not related to coal type. It is suggested that the observed trend is related to a decrease in the heterogeneity of the pore surfaces, and subsequent increased coverage by the adsorbate, as coal rank increases. Desorption rate studies on crushed samples show that dull coals desorb more rapidly than bright coals and that desorption rate is also a function of rank. Coals of lower rank have higher effective diffusivities. Mineral matter was found to have no influence on desorption rate of these finely crushed samples. The evolution of the coal pore structure with changing rank is implicated in diffusion rate differences. 相似文献
17.
Organic matter maturity and oil/gas prospects in Middle-Upper Proterozoic and Lower Paleozoic carbonate rocks in northern China 总被引：3，自引：0，他引：3
Middle-Upper Proterozoic and Lower Paleozoic carbonate formations in northern China are well developed with an accumulative
thickness of 6000–1400 m. Both seepages and oils have been found in the outcrops and drilling wells.
The maturity of organic matter in these carbonate formations in obviously lower than that in southern China, as viewed from
reflectance (R°), H/C (atomic ratio), the amount and distribution of hydrocarbons,T
max°C and so on.T
max°C may be used as a principal index for determining the maturity of organic matter in carbonate rock-covered areas. According
to the results of themeasurement ofT
max°C andR° for natural samples and simulating experiments on bitumens from carbonate rocks, the limitation values for oil and gas have
been estimated at 455°C (R°=1.35) and 476°C(R°=2.25), respectively. On this basis, the map of organic matter maturity for the Middle-Upper Proterozoic, Ordovician, Cambrian
and Carboniferous of northern China has been compiled. It has been proposed that prospects of both oil and gas are expected,
with oil and condensate dominant in the Ordovician, and condensate and dry gas in the Middle-Upper Proterozoic. The Cambrian
is intermediate between them. 相似文献
18.
Thermally altered pods of coal of very high rank have been observed in a high-volatile-bituminous coal seam in the eastern side of Eagle Mountain, Elk Valley Coalfield, British Columbia. Rank changes have been measured over a strike distance of 7.5 m from 1.24% to 7.1% Ro max, corresponding to a rank gradient of 0.78% Rom−1.Petrologically, unaltered to extremely altered vitrinite showing nongranular (basic) anisotropy, mosaic-textured liptinite and pyrolytic carbon are the most abundant components. The limited presence of mosaic on vitrinite is an indication that the coal seam may have been weathered prior to being heat-affected.Evidence points to localized temperatures as high as 1,000°C, which could have been caused by a lightning strike. The eastern side of Eagle Mountain has experienced higher temperatures than the western side, and it appears that the heat ‘front’ and zone of alteration have an irregular pattern, pointing to saturation of parts of the coal seam by water.Four types of pyrolytic carbon having distinct morphology, anisotrophy and optical path with increasing temperature were observed. Reflectance of pyrolytic carbon falls within the zone of heat-affected coals, whereas the optical path of heat-affected Seam 15 samples is different from that of fresh coal with increasing rank.Finally, the reflectance of vitrinite in heat-affected coal is higher than the reflectance of vitrinite in carbonaceous shale in the Seam 15 section. 相似文献
19.
一种页岩含气性热演化规律研究的模拟实验方法 总被引：2，自引：1，他引：1
目前针对页岩气赋存规律研究的热模拟实验主要是沿袭常规油气热模拟方法,以粉末态样品开展模拟,研究对象为岩石生成并排出的烃类气体,这种模拟方式未明确页岩气的实质为"滞留气",并且模拟后样品无法开展扫描电镜分析,不能确定岩石孔隙结构变化规律。本文通过石英玻璃管封装块状样开展页岩生烃热模拟实验,并结合一套数据处理方法,尝试建立了一种适合页岩气研究的热模拟实验方法,研究泥页岩在不同演化阶段(Ro范围为0.596%~2.143%)不同赋存状态气体的含量以及岩石微观孔隙特征的变化情况。结果表明,泥岩及油页岩样品的排出气及解析气含量在高成熟度阶段(400℃以后)有明显增加的趋势,结合扫描电镜微观结构分析显示这是由于有机质生气量以及无机孔隙均有增加。本方法可以研究页岩热演化过程中不同赋存状态气体含量及微观孔隙结构的变化,为页岩气勘探开发提供了一种可参考的方法。 相似文献
20.
The objective of the study was to characterize changes of reflectance, reflectance anisotropy and reflectance indicating surface (RIS) shape of vitrinite, sporinite and semifusinite subjected to thermal treatment under inert conditions. Examination was performed on vitrinite, liptinite and inertinite concentrates prepared from channel samples of steam coal (Rr = 0.70%) and coking coal (Rr = 1.25%), collected from seam 405 of the Upper Silesian Coal Basin. The concentrates were heated at temperatures of 400–1200 °C for 1 h time in an argon atmosphere.All components examined in this study: vitrinite, sporinite and semifusinite as well as matrix of vitrinite and liptinite cokes, despite of rank of their parent coal, show, in general, the most important changes of reflectance value and optical anisotropy when heated at 500 °C, 800 °C (with the exception of bireflectance value of sporinite) and 1200 °C.After heating the steam coal at 1200 °C, the vitrinite and the semifusinite reveal similar reflectances, whereas the latter a slightly stronger anisotropy. Sporinite and matrix of liptinite coke have lower reflectances but anisotropy (Rbi and Ram values) similar to those observed for vitrinite and semifusinite. However, at 1000 °C sporinite and matrix of liptinite coke have the highest reflectivity of the studied components. The RIS at 1200 °C is the same for all components.The optical properties of the three macerals in the coking coal become similar after heating at 1000 °C. Coke obtained at 1200 °C did not contain distinguishable vitrinite grains. At 1200 °C semifusinite and vitrinite coke matrix have highest Rr values among the examined components. Maximum reflectance (Rmax) reach similar values for vitrinite and sporinite, slightly lower for semifusinite. Matrix of liptinite coke and matrix of vitrinite coke have considerably stronger anisotropy (Rbi and Ram values) than other components. RIS at 1200 °C is also similar for all components. 相似文献