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论韧性剪切带研究及其地质意义 总被引：4，自引：1，他引：3
系统研究韧性剪切带变形岩在天然强剪切应力作用条件下常量元素迁移机制及活化转移的应力排序、微量元素迁移的动力控制、稀土元素配分变化和变形矿物晶体化学变异的应力制约等构成了当代韧性剪切带研究的前沿课题,也是当前糜棱岩岩石地球化学研究难点和精华所在。其研究成果将对动力成岩（成矿）机理的认识有重要的突破,具有重要的理论意义和潜在应用价值。对韧性剪切带及其变形岩石的研究现状和研究意义进行系统的综述,提出了未来韧性剪切带及其糜棱岩的研究方向和目标:
①系统研究糜棱岩中主要造岩矿物组合及其变形特征,计算剪切变形岩石的应力—应变参数,搞清韧性剪切带所处的应力应变环境;②系统研究韧性剪切带岩石在天然分强剪切应力作用条件下常量元素迁移机制及活化转移的应力排序问题;③系统研究剪切变形作用过程中岩石化学组成的微量和稀土元素变化,讨论强变形条件下岩石中微量元素活化和迁移规律,深入探讨微量元素迁移的动力控制,包括稀土元素配分变化的应力制约以及应变矿物晶格化学变化行为及其对其寄主的变形岩石元素（组分）在应变过程中迁移变化的制约和影响;④从理论上探讨天然强剪切应变条件下岩石中组分活化、转移与应力（应变）的因果联系,为深入探讨韧性剪切带动力成岩（成矿）作用提供理论的科学依据,为探讨中、下地壳中韧性剪切带的形成和演化提供科学依据（如韧性剪切带金的富集）,同时为韧性剪切变形作用条件下成岩、成矿地球化学作用提供理论和实验依据;⑤现代分析技术如激光同位素原位分析以及激光ICP MASS分析技术对研究变形域内的岩石（矿物）的元素和同位素的活化迁移规律,对深刻揭示糜棱岩化过程中的元素活化迁移机制提供更高质量的地球化学证据具有重要的作用。 相似文献
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<正> 韧性剪切带中物质组分迁移集散的一般解释是:由于岩石破碎变形,带内流体活动增强;在水—岩作用过程中,流体与变形岩石之间产生物质组分交换和重新分配。但各元素发生迁移的一个前提条件是:在韧性剪切作用的物化条件下,其地球化学性质是活泼的。本文对武夷山隆起带黎川茅店韧性剪切带中物质组分的迁移规律进行了初步研究,结果表明,P_2O_5、Fe_2O_3、灼失量和V、 相似文献
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郯庐断裂带南段中深层次剪切带糜棱岩化过程中组分变化规律研究 总被引：6，自引：0，他引：6
对郯庐断裂带南段两条典型的中深层次的声望生剪切带中的糜棱岩的系统研究，揭示了韧性剪切变莆作用对岩石化学级份迁移活化的制约和影响，在对活动组分迁移得失的模拟计算的基础，建立岩石组分迁移变化的变质反应化学方程式，综合讨论了流体在糜凌岩化过程中所起的重要作用。 相似文献
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南岗-高公岛韧性剪切带是一条自南东向北西斜向逆冲的岩片边界性构造带,糜棱岩化作用强烈。韧性变形过程中,岩石中的主要矿物长石、黑云母等发生了不同程度的分解或蚀变并导致组分迁移。其中,活动组分的迁移是流体渗滤作用引起的,不活动组分的变异是体积亏损造成的。通过对韧性剪切带内不同变形程度岩石主要地球化学组分的对比分析,确立等比线斜率,计算出初糜棱岩的体积亏损率约为17%,糜棱岩的体积亏损率约为27%;质量平衡计算结果及等比线图表明韧性剪切作用导致SiO2流失量最大,其次为Al2O3,FeO、CaO、Na2O等都有不同程度的丢失,表明它们具有较强的活动性,MgO位于等比线上方,属于带入组分。糜棱岩中的石英或长英质条带和团块是长石的钠黝帘石化、绢云母化和黑云母的绿泥石化等导致SiO2、Al2O3、Na2O、CaO、FeO等活动组分从岩石中析出迁移形成的。这种岩石体积亏损和组分迁移是部分难溶组分富集的重要机制,对研究韧性剪切带中长英质条带和部分贵金属矿床的形成机制具有重要的指导作用。 相似文献
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含金剪切带蚀变特征及其与金成矿的关系——以新疆天格尔金矿带为例 总被引：1，自引：0，他引：1
含金剪切带剪切变形过程中构造、流体-岩石相互作用导致系统内组分的迁移和再分配，这些过程控制着含金剪切带内蚀变特征及其金的成矿作用。在含金剪切带脆-韧性变形域内，成矿层次从深到浅矿石类型由蚀变糜棱岩型向石英脉型过渡，矿床成因类型由韧性剪切带型向蚀变破碎带型过渡，是主期剪切成岩成矿过程中不同时空演化阶段的产物。 相似文献
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构造变形与流体联合控制成矿作用的机制是矿床学界关注的热点问题之一。作为大陆岩石圈中的应变局部化带,剪切带中一般都渗透着大量流体,流体与岩石的相互作用及其化学效应和物理效应,导致了矿物化学不平衡和组分的迁移,引起岩石化学成分重新调整。文章通过对韧性剪切带内的流体作用、剪切带内的成分与体积变化、剪切变形与成矿模拟实验总结,讨论了剪切变形过程中的力学-化学作用、剪切构造应力和流体在构造成岩成矿过程中的行为。因此,要加强构造应力对温度、岩石物理性质、地球化学相平衡和水岩体系的相关参量方面影响的综合研究。 相似文献
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构造动力成岩成矿作用的实验研究 总被引：1，自引：1，他引：1
岳石 《大地构造与成矿学》1990,14(4):325-332
采用高温高压岩石蠕变实验装置,对实际的岩石进行高温高压变形实验,通过观察和测试样品组构和成份的变化,考察一定温压条件下,岩石的构造变形所带来的物质组分的迁移和聚集,探讨构造动力控制成岩成矿作用的机理。实验结果表明:伴随构造变形,物质组分迁移 主要可归纳为三种类型:1)塑性或韧性流动;2)扩散与化学反应;3)热液携带。在实验后的样品中观察到:黄铣矿通过韧性流动沿韧性剪切带,韧性挤压带和韧性扭曲构造带的迁移和富集;斜长石和黑云母发生矿物成份和矿物相的转化。在实验变形过程中,Cu,Pb,Zn等成矿元素易于活化迁移,从高压区迁向低压区,K,Na,Ca,Mg等成岩元素也易活化迁移,但规律不明显,Fe,Co,Ni等元素对花岗岩样品不易活化迁移而对矿石样品则易迁移。上述实验结果对探讨成矿规律具有非常重要意义。 相似文献
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西藏阿里札达韧性剪切带特征及其X光岩组分析 总被引：1，自引：0，他引：1
文中简述了西藏阿里札达盆地的地质背景、区域地层和札达韧性剪切带的基本特征。采用X射线衍射法对札达韧性剪切带中的石英、方解石和白云母等三种矿物,进行了X光岩组分析,确定了韧性变形岩石的组构特征、韧性剪切带的属性和变形岩石的应变类型,以及韧性剪切带形成时的温压条件。研究表明,韧性变形岩石均具不对称组构,反映韧性带属于南盘(下盘)俯冲型韧性剪切带,韧性变形是在高温、高压、低应变速率条件下发生的,处于>10km的地壳深度,岩石应变类型以压扁应变为主。 相似文献
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韧性剪切变形对岩石地球化学行为的制约——以北阿尔金巴什考供韧性剪切带为例 总被引：6，自引：0，他引：6
韧性剪切变形对岩石地球化学行为的制约一直是地质学家们探讨的课题。本文以构成北阿尔金红柳沟——拉配泉俯冲碰撞杂岩带与北阿尔金地块边界的巴什考供斜向逆冲型韧性剪切带为例，通过对韧性剪切带内花岗岩变形前后不同变形强度构造岩的地球化学组成进行对比，确定等比线斜率，探讨韧性变形对岩石体积和成分变异的影响。计算结果表明，在糜棱岩化过程中，糜棱岩化花岗岩体积亏损21％，花岗质糜棱岩体积亏损31％。质量平衡计算结果和等比线图表明，韧；陛剪切作用导致SiO2，流失量最大，A12O3、K2O及Ba、Rb、Sr等都有不同程度的丢失，显示出较强的活动性，MnO、P2O5、Sc位于等比线上或附近，表现出相对的稳定性。岩石中活动组分的变异是流体渗滤作用引起的，不活动组分的变异是体．积亏损造成的。 相似文献
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YANG Xiaoyong LUI Deliang YANG Xueming WANG KuirenDepartment of Earth Space Sciences Advanced Centre for Earth Sciencesand Astronomy University of Science Technology of Chin the Third World Academy of Sciences Hefei Anhui DAI JinxingResearch Institute of Petroleum Exploration Development China National Petroleum Corporation Beijing Zhu Xiling 《《地质学报》英文版》1998,72(1):37-50
On the basis of field geology, three typical ductile shear zones in the southern part of the Tancheng-Lujiang fault belt have been chosen for a detailed study. Altogether ten samples of the tectonites have been collected for this study. The paper is focused on a comprehensive study of the tectonites in the medium-lower horizons of the ductile shear zones. The mineral compositions of the rocks are analyzed with EPMA and some typical whole-rock samples analyzed by chemical and ICP methods. Based on the comprehensive study of the characteristics of the deformation, the mineral assemblages and the changes of chemical composition of the bulk rocks, this paper presents a discussion on the relationship between the volume loss, the fluid flow and compositional changes during mylonitization of the ductile shear zones in this region. Our study shows that there are a large amount of fluids flowing through the shear zones during the process of mylonization, accompanied by the loss of rock volume and migration of el 相似文献
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Interdependence of deformation, fluid infiltration and reaction progress recorded in eclogitic metagranitoids (Sesia Zone, Western Alps) 总被引：1，自引：0，他引：1
G. L. FRÜH-GREEN 《Journal of Metamorphic Geology》1994,12(3):327-343
The effects of high-strain deformation and fluid infiltration during Alpine eclogite facies metamorphism have been studied across ductile shear zones in relatively undeformed metagranitoids at Monte Mucrone (Sesia Zone, Western Alps, Italy). Microfabrics together with bulk rock and stable isotope data indicate that the mineralogical and chemical variations are related to the degree of deformation, rather than to changes in P-T conditions or tectonic position. Transformation of meta-quartz diorite to recrystallized eclogitic mylonites involved the breakdown of biotite and plagioclase and required the influx of H2O. Bulk-rock geochemical data show that ductile deformation to form eclogitic mylonites involved an increase in volume with a weight percent gain in H2O and Si and variable loss of K, Na, Ca and Al. δ18O changes systematically across ductile shear zones into the undeformed country rocks. Constant values in shear zone centres indicate advection parallel to the shear zone and within 10 cm of the mylonites. A dominant component of diffusive oxygen exchange perpendicular to the shear zones produced isotopic fronts, evident from a gradual increase in δ18O values to the reference values of the country rocks. The degree of isotopic shift within the shear zones reflects increasing deformation and degree of reaction progress. Multiple phases of Alpine deformation and mineral growth are recognized in the Monte Mucrone metagranitoids, and in some cases, eclogite facies shear zones were reactivated under greenschist facies conditions. The results of this study suggest that high-strain deformation provided pathways for both synkinematic and post-kinematic metamorphic fluids which were necessary for complete reactions. Relict igneous fabrics, as well as the presence of corona textures around biotite and pseudomorphs after primary igneous plagioclase in the least deformed rocks, indicate a paucity of hydrous fluids and support the conclusion that fluid movement was channelled rather than pervasive. 相似文献
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本文以武夷山隆起带中段茅店韧性剪切带为例，通过镜下观察和化学分析，对韧性剪切带中两个系列的糜棱岩与其相应的原岩在矿物成分和化学组分等方面进行了对比分析，以探讨构造形变过程中物质成分的迁移、集散规律。同时，对惰性组分的集散机制进行了初步探讨。 相似文献
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Rock Deformation, Component Migration and ^18O/^16O Variations during Mylonitization in the Southern Tan-Lu Fault Belt 
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下载免费PDF全文 YANG Xiaoyong LIU Deliang FENG Min YU Qingni WANG Kuiren 《《地质学报》英文版》2007,81(2):297-311
This paper discusses the relationship between the volume loss, fluid flow and component variations in the ductile shear zone of the southern Tan-Lu fault belt. The results show that there is a large amount of fluids flowing through the shear zone during mylonitization, accompanied with the loss of volume of rocks and variations of elements and oxygen isotopes. The calculated temperature for mylonitization in different mylonites ranges from 446 to 484℃, corresponding to that of 475 to 500℃ for the wall rocks. The condition of differential stress during mylonization has been obtained between 99 and 210 MPa, whereas the differential stress in the wall rock gneiss is 70-78 MPa. The mylonites are enriched by factors of 1.32-1.87 in elements such as TiO2, P2O5, MnO, Y, Zr and V and depleted in SiO2, Na2O, K2O, Al203, Sr, Rb and light REEs compared to their protolith gneiss. The immobile element enrichments are attributed to enrichments in residual phases such as ilmentite, zircon, apatite and epidote in mylonites and are interpreted as due to volume losses from 15% to 60% in the ductile shear zone. The largest amount of SiO2 loss is 35.76 g/100 g in the ductile shear zone, which shows the fluid infiltration. Modeling calculated results of the fluid/rock ratio for the ductile shear zone range from 196 to 1192 by assuming different degrees of fluid saturation. Oxygen isotope changes of quartz and feldspar and the calculated fluid are corresponding to the variations of differential flow stress in the ductile shear zone. With increasing differential flow stress, the mylonites show a slight decrease of δ^18O in quartz, K-feldspar and fluid. 相似文献
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韧性剪切带内流体作用的研究 总被引：10，自引：3，他引：7
韧性剪切带内的流体作用是一种复杂的构造物理化学过程和力学－化学的耦合过程。它不仅影响着岩石的变形机制,促进变形构造的发生和发展,而且影响着岩石的矿物组成及化学成分的变化。本文在综合评价现有研究成果的基础上认为,岩石的成分变异和体积变化是韧性前切带内流体作用研究的主要内容,韧性剪切带内构造－流体演化历史,构造物理化学、岩石应变模式及其特征的研究是今后韧性剪切带内流体作用研究的发展方向和前沿领域。 相似文献
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Fluid-rock interaction in some shear zones from the Pyrenees 总被引：4，自引：0，他引：4
A. M. McCAIG 《Journal of Metamorphic Geology》1984,2(2):129-141
Abstract Mylonites from shear zones cutting Hercynian gneisses in the central Pyrenees have been studied in thin section and using the electron microprobe. The shear zones contain retrogressive greenschist facies assemblages implying introduction of an aqueous fluid during deformation in the zones. Textural evidence suggests that fluid-rock interaction occurred throughout the active life of the shear zones.
Whole-rock chemical changes during deformation are documented in a variety of mylonitic lithologies and retrogressed country rocks. The overall effect was to reduce chemical differences between lithologies. Activity diagrams show that this would be expected if a hydrous fluid was circulating between different lithologies during deformation. In most cases fluid/rock ratios were relatively small resulting in gradual chemical changes and repeated recrystallization. 'Open-system'behaviour with reduction in the number of phases is seen in some granite mylonites, suggesting focusing of fluid movement in parts of the shear zones. Continual fluid-rock interaction may have led to reaction-enhanced ductility in the shear zones over a long period of time. The source of fluid is uncertain, but may be related to underthrusting of material beneath the area investigated. 相似文献
Whole-rock chemical changes during deformation are documented in a variety of mylonitic lithologies and retrogressed country rocks. The overall effect was to reduce chemical differences between lithologies. Activity diagrams show that this would be expected if a hydrous fluid was circulating between different lithologies during deformation. In most cases fluid/rock ratios were relatively small resulting in gradual chemical changes and repeated recrystallization. 'Open-system'behaviour with reduction in the number of phases is seen in some granite mylonites, suggesting focusing of fluid movement in parts of the shear zones. Continual fluid-rock interaction may have led to reaction-enhanced ductility in the shear zones over a long period of time. The source of fluid is uncertain, but may be related to underthrusting of material beneath the area investigated. 相似文献
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大青山高级变质岩不仅记录华北克拉通早期大陆形成演化历史,也保留了中下部地壳岩石流变信息,它们经历了下部地壳构造层次高角闪岩相-麻粒岩相条件变质变形、深熔作用改造,形成了复杂构造样式和构造要素组合.韧性剪切带是高级变质岩中主要构造形迹,控制着早前寒武纪高级变质岩主体构造格架.依据野外地质产状、变形特征与构造要素叠加改造关系,韧性剪切带划分为早期近水平顺层伸展型和晚期陡倾韧性剪切带.近水平顺层伸展韧性剪切带呈残留状保留在后期变形改造较弱部位上,主要沿着不同地质单元或者岩性层界面上发育,是在伸展变形体制下形成的.晚期陡倾韧性剪切带呈近东西方向展布,规模较大,叠加和改造早期构造形迹,形成于晚期造山挤压构造环境中,以左行滑移为主.这两种韧性剪切带都形成于地壳中深部构造层次高角闪岩相-麻粒岩相条件下,变形机制主要为熔体增强颗粒边界扩散和颗粒流动,使岩石发生大规模的塑性流动.在宏观上形成了不对称流动组构、条纹条带构造、熔融线理、层内流动褶皱等构造形迹,在微观上矿物晶体没有发生明显塑性变形,均匀消光,晶体为三边平衡结构,与静态变质结构相似,形成了地壳深部构造层次上变质构造岩-构造片麻岩. 相似文献