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1.
使用活塞-圆筒式高温高压装置进行一系列榴辉岩部分熔融熔体与橄榄岩反应实验,可以为深入了解俯冲带壳-幔相互作用的影响因素及地幔不均一性的成因提供重要信息.实验使用反应偶的方法,并在0.8~3.0 GPa和1 200~1 425℃条件下进行.实验结果表明,榴辉岩部分熔融熔体-橄榄岩反应的动力学和结果受控于熔体主量元素成分、熔体中的H2O、温度、压力和橄榄岩的物理状态等因素.大陆俯冲带地幔岩石中斜方辉石的富集是再循环陆壳熔体与上覆地幔反应的结果,地幔岩石中斜方辉石岩脉的形成与含水熔体交代有关,地幔岩石中的石榴辉石岩和石榴石岩可能形成于高压、低温条件下的熔体-橄榄岩反应. 相似文献
2.
上地幔流体的性质和作用——从女山幔源二辉橄榄岩捕虏体获得的证据 总被引：2，自引：0，他引：2
玄武岩浆从地幔深处挟带上来的超镁铁质捕虏体含有地幔流体的直接证据,它们对于阐明地幔深部地质作用(部分熔融作用、地幔交代作用)的机制十分重要。女山幔源二辉橄榄岩的研究结果表明,初始的地幔流体除富含CO_2外,尚含有H_2O和少量CO、CH_4、SO_2、C1、F。地幔中的初始流体(挥发组分)在源部是溶解于地幔橄揽岩的高压固体矿物相中,它们在地幔上隆减压时出溶,形成细小的最早期流体包裹体。这些自由流体相在一定部应聚集,使得地幔固相线(和液相线)下降,引起上地幔发生减压部分熔融。初始的部分熔融主要发生于矿物边界,以单斜辉石最易遭受,形成矿物边缘的海绵状部分熔融带。当地幔剪切流动时,初始的部分熔融体珠滴联合成大的珠滴,并开始渗透,在变形橄榄岩中相连成脉状网络,晚期含C0_2岩浆包裹体及填隙玻璃即为其代表。由于剪裂作用,熔体(和流体)压裂开上覆橄榄岩,产生岩墙状通道,并在上地幔的某些低压区聚集成岩浆库。流体和熔体均为地幔交代作用的介质。在流体参与下,上地幔低度部分熔融产生的熔体将高度富集不相容元素。这些熔体和流体与亏损地幔间的相互作用,可以带来不相容元素重大的局部富集。当流体(和熔体)中H_2O浓度低时,仅发生隐交代作用;当H_2O浓度较高时,部分熔融程度也较高,相应有含水相(如角闪石等)成核,出现矿物交代作用。 相似文献
3.
地幔矿物与水流体之间元素分配系数的研究及意义 总被引：1，自引：0，他引：1
流体是地球内部物质和能量迁移最为活跃的介质，它在造成地幔化学的富集和亏损，产生具有不同地球化学特征的幔源岩浆岩石，以及促进壳幔物质的再循环过程等诸多方面都起了重大作用，高温高压下实验模拟流体与地幔岩石和矿物之间痕量元素分配作用是揭示地幔流体的组成与性质，地幔中不同元素类型之间或内部的分异作用，地幔交代介质的类型与特征，岛孤玄武岩高场强元素亏损原因的一个重要的手段，并对近年来有关高温高压下流体与地幔矿物之间痕量元素分配作用的实验模拟研究进行了评述，分析了制约流体与地幔矿物之间痕量元素分配系数的因素，总结了这些研究的应用。 相似文献
4.
实验岩石学通过高温高压实验来模拟地球内部状态,正演研究矿物、岩石及其组分的物理化学行为,与天然矿物和岩石样品反演研究相互补充. 从20世纪初美国卡内基研究所建立地球物理实验室算起,实验岩石学已经历了100多年的发展,在认识地球内部状态和过程以及矿物和岩石成因方面发挥了重要作用. 我国实验岩石学研究开展约50年,进入21世纪以来在实验平台和创新性研究成果方面取得了显著进步. 在学科发展趋势方面,实验岩石学表现出以下6方面的特点:（1）新的高温高压实验技术不断涌现;（2）实验与分析测试技术高度融合;（3）实验模拟与计算模拟相结合;（4）从热力学平衡扩展到动力学研究;（5）从干体系扩展到对挥发分和流体的深入研究;（6）应用场景从固体地球扩展到类地行星. 通过进一步开发或改进高温高压实验技术,加强与分析测试技术以及计算技术的结合,实验岩石学有望在破解地球内部流体的性质和作用、地幔演化和岩浆分异、变质反应速率和机制、类地行星形成与演化等重要科学问题方面作出关键贡献. 相似文献
5.
地幔橄榄岩部分熔融的实验研究——论地幔富硅酸盐流体(熔体)的成因 总被引：1，自引：0，他引：1
在0.61 GPa和1.0 GPa条件下,进行了地幔二辉橄榄岩的部分熔融实验,首次探讨了熔体成分在“不同熔融阶段”随部分熔融程度的变化。结果显示,熔体中SiO_2、CaO、Al_2O_3、Na_2O和TiO_2变化趋势在不同熔融阶段不一样。熔体成分在低压下或较高压下相对富SiO_2。幔源富硅酸盐流体(熔体)的成因有多种,但存在于同一地幔橄榄岩捕虏体中、挥发分及碱质含量相近而其他成分不同的基性—中酸性富硅酸盐熔体,是在有地幔C—O—H流体介入或其他交代矿物存在时的原位局部平衡 相似文献
6.
在六合霓辉正长斑岩中广泛发育的各类包体岩石中，新近发现了三类特殊包体。通过岩相学、岩石化学、电子探针和扫描电镜分析研究表明，纯方解石包晶（体）和含石英的黄玉伟晶岩包体是地幔流体在运移过程中发生去气作用的产物；黑色微晶富铁硅酸盐熔融包体是地幔流体伴随去气作用的分离产物，其主要矿物组成为石英、绿泥石和富铁的柱状和片状硅酸盐矿物，特征矿物有自然铁、磷灰石和锆石；据全岩化学成分和矿物组成特征及结晶状态分析，表明该包体岩石不是常规岩浆作用产物，尤其自然铁的存在进一步证明该微晶熔融包体是还原条件或缺氧环境下的地幔流体物质。通过对特殊包体岩石的研究，为该区不同岩性和地层中的多金属成矿提供了重要的深部过程地球化学背景。 相似文献
7.
地幔部分熔融过程中亲S元素Ag的分配行为能够限定地幔中Ag含量,同时可以追踪地幔中S含量和去向。在地幔部分熔融过程中, Ag的分配行为与其在地幔硅酸盐矿物–玄武质熔体间的分配系数密切相关。因此准确地测定Ag在除硫化物之外地幔硅酸盐矿物和共存熔体之间的分配系数是预测Ag分配行为的必要条件之一。目前缺乏Ag在地幔矿物(橄榄石、辉石等)和玄武质熔体之间分配系数的报道,阻碍了对Ag在地幔部分熔融过程中分配行为的研究。本研究通过高温高压实验获得了在洋中脊玄武岩(MORB)产生的温度和压力条件下,Ag在橄榄石(ol)、斜方辉石(opx)、单斜辉石(cpx)与玄武质熔体(melt)之间的分配系数,分别为DAgol/melt=0.0005±0.0002、DAgopx/melt=0.007±0.003和DAgcpx/melt=0.046±0.009。根据实验获得的分配系数进行模拟的计算结果表明,太古代科马提岩和洋中脊苦橄岩源区的地幔Ag含量为(8±2)×10-9。如果这个值... 相似文献
8.
《吉林大学学报(地球科学版)》2015,(Z1)
<正>地幔交代作用及地幔流体研究是深部地质过程研究的热点问题之一。地幔交代作用不仅关系到地幔深部的部分熔融,而且对地幔源岩浆的性质的研究具有重要的指示意义,对于我们理解岩石圈地幔的演化形成、大陆动力学机制以及岩浆作用有很大的帮助。地幔交代介质通常根据组分分成碳酸盐熔体、富H2O-CO2流体、玄武质熔体和富硅熔体等,这些交代熔体可能源于再循环的大陆地壳、软流圈地幔或俯冲洋壳。由于地幔交代作用交代介质及其来源复杂多样,因此如何鉴别地幔交代作用类型和进一步认识熔体在地幔中 相似文献
9.
10.
豆荚状铬铁矿是蛇绿岩的特征性矿产,对其成因的认识还存在较大的分歧,包括:（1）早期岩浆熔离;（2）地幔熔融残余;（3）熔体-岩石反应.豆荚状铬铁矿及其围岩地幔橄榄岩中大量异常地幔矿物群的发现,引起了地质学家对其形成过程的重新思考.回顾了铬铁矿的研究,借助pMELTS热力学软件模拟浅部地幔过程,使用定量化的方法限定这些过程对豆荚状铬铁矿形成的贡献,通过一个新的角度讨论其形成.初步模拟结果显示,单独的地幔部分熔融、熔体分离结晶以及拉斑质熔体与亏损地幔的反应等过程形成的铬铁矿,无论在数量还是品位上都难以达到矿床水平,暗示豆荚状铬铁矿的形成可能为多种作用耦合的结果,或与深部地幔作用有关. 相似文献
11.
《Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy》2000,25(2):209-214
Water fluids in the Earth's crust may initiate a number of mineral reactions resulting in different microstructure changes, which may appear in the form of intergranular melt films and interstitial phases. Therefore, they have an essential influence on elastic wave velocities of rocks (for example, sandstone, amphibolite, basalt). The aim of the experiment was to determine the conditions of the silicate liquid and others interstitial phases distribution in the rock intergranular space.The results obtained using the ultrasonic method at temperature up to 950 °C and under fluid pressure of 300 MPa revealed that the formation of intergranular melt films and interstitial phases network depend on chemical composition of fluids. The experiments with use of a high-temperature centrifuge at temperature 1400 °C showed that the amount of melt films, higher than 6 %, is sufficient to form a system of interconnected intergranular channels. These studies can be contributed to the petrophysical and geochemical interpretation of geophysical measurements. 相似文献
12.
上地幔熔体-岩石相互作用与大陆地幔演化 总被引：11，自引：2，他引：9
根据实验岩石学、幔源岩石的岩石地球化学资料以及微量元素地球化学理论模拟等,评述了上地幔熔体岩石相互作用研究领域的最新进展,指出熔体岩石相互作用不仅深刻地制约了岩石圈地幔的矿物学、地球化学和物理性质的变化以及地幔不均一性的形成及演化,而且也会最终控制各种构造环境下喷出岩浆的地球化学特征,以及深部岩浆的分离机制。 相似文献
13.
V. N. Sharapov A. A. Tomilenko S. Z. Smirnov V. V. Sharygin S. V. Kovyazin 《Petrology》2013,21(5):427-453
In this paper, we discuss the formation conditions of rhyolites and results of their interaction with later portions of basic magmas on the basis of the investigation of melt and fluid inclusions in minerals from a rhyolite xenolith and host neovolcanic basalts of the Cleft segment of the Juan de Fuca Ridge. In terms of bulk chemistry and the compositions of melt inclusions in pyroxene and olivine phenocrysts, the basic rocks of the southern part of this segment are typical MOR basalts. Their olivine, clinopyroxene, and plagioclase crystallized at temperatures of 1160–1280°C and a pressure range between 20 and 100 MPa. The xenolith is a leucocratic rock with negligible amounts of mafic minerals, which clearly distinguishes it from the known occurrences of silicic rocks in the rift valleys of MOR. The rhyolite melt crystallized at temperatures of 900–880°C. The final stages of rhyolite melt crystallization at temperatures of 780–800°C were accompanied by the release of a saline aqueous fluid with high chloride contents. Based on the geochemical characteristics of melt inclusions and melting products, it can be suggested that the magmatic melt was produced by melting of metamorphosed oceanic crust within the Cleft segment under the influence sof saline aqueous fluid trapped in the pores and interstices of the rock. The rock represented by the xenolith is a late differentiation product of such melts. The ultimate products of silicic melt fractionation show high volatile contents: H2O > 3.0 wt %, Cl ～ 2.0 wt %, and F ～ 0.1 wt %. The interaction of the xenolith with the host basaltic melt occurred at temperatures equal or slightly higher than those of ferrobasalt melts (1190–1180°C). During ascent the xenolith occurred for a few tens of hours in high-temperature basic magma, and diffusion exchange between the basaltic and silicic melts was very minor. 相似文献
14.
Fluids and Melts in the Upper Mantle 总被引：3，自引：0，他引：3
XIA Linqi XIA Zuchun XU XueyiXi''an Institute of Geology Mineral Resources Chinese Academy of Geological Sciences East Youyi Rd. Xi ''an Zhu Xiling 《《地质学报》英文版》1999,73(3):330-340
This paper presents a direct study of the fluids and melts in the upper mantle by examining the fluid inclusions, melt inclusions and glasses trapped in the mantle lherzolite xenoliths entrained by Cenozoic alkali basalts (basanite, olivine-nephelinite and alkali-olivine basalt) from eastern China. The study indicates that the volatile components, which are dissolved in high-pressure solid mineral phases of mantle peridotite at depths, may be exsolved under decompressive conditions of mantle plume upwelling to produce the initial free fluid phases in the upper mantle. The free fluid phases migrating in the upper mantle may result in lowering of the mantle solidus (and liquidus), thereby initiating partial melting of the upper mantle, and in the meantime, producing metasomatic effects on the latter. 相似文献
15.
Morphology of intergranular pores and wetting angles in pelitic schists studied by transmission electron microscopy 总被引：2，自引：0，他引：2
Takehiko Hiraga Osamu Nishikawa Toshiro Nagase Mizuhiko Akizuki 《Contributions to Mineralogy and Petrology》2001,141(5):613-622
In pelitic schists composed mainly of quartz and albite grains, the morphology of intergranular pores, which were filled with water, was studied by transmission electron microscopy (TEM). Although some pores are defined by crystallographic planes (F-face), most of their form has an ideal shape determined by interface tensions between grains and fluid. High-resolution TEM observations demonstrate that pore-free regions at grain boundaries are tight even at the nanometer scale, showing that the wetting angle is larger than 0° in this rock. The pore distribution in two-grain junctions can be compared to a "necklace microstructure" developed by instability of a fluid film along the boundary induced by microcracking. Wetting angles for pores located at grain edges of quartz and albite decrease in the order albite/albite, quartz/quartz, and quartz/albite. The quartz/quartz wetting angle in a calcite-free sample is smaller than that in a calcite-containing sample. This angle also changes due to grain misorientation. Our results confirm that solid-solid and solid-fluid interfacial energies control the geometry of intergranular fluid in natural rocks. 相似文献
16.
安徽铜陵地区中酸性侵入岩及其岩石包体中的矿物包裹体研究 总被引：14，自引：2，他引：14
铜陵地区是长江中、下游铁、铜、硫、金成矿带的重要组成部分。笔者对铜陵地区中酸性侵入岩及其岩石包体中的包裹体进行了较系统的岩相学、显微测温和激光拉曼光谱研究。通过岩相学观察发现了 3类包裹体 ,即晶质熔融包裹体、流体熔融包裹体和流体包裹体。显微测温资料表明 ,本区的岩浆流体成矿演化可分为 3个阶段 :岩浆阶段 ( >12 5 0～ 90 0℃± )、过渡岩浆阶段 ( 90 0～ 75 0℃± )和岩浆期后热液阶段 ( <75 0℃ )。部分熔浆的温度之高 (可达 12 5 0℃ ) ,表明其可能是底侵幔源岩浆同熔下地壳形成的。在老庙基岩体、小铜官山岩体、鸡冠石岩体和小陶家岩体中产有晶质熔融包裹体、流体熔融包裹体和流体包裹体这 3种包裹体 ,表明相应的岩浆流体演化具有连续性、继承性和阶段性 ,其对应的成矿溶液以岩浆热液为主 ;与此不同的是 ,在鸡冠山岩体和白芒山岩体中仅产有晶质熔融包裹体和流体包裹体两种类型的包裹体 ,表明相应的岩浆流体演化不具连续性 ,其对应的成矿溶液以天水热液为主。此外 ,在小铜官山岩体和鸡冠石岩体的中酸性侵入岩中 ,发现了不混溶包裹体 ,其可能是在压力释放条件下形成的。 相似文献
17.
Monique Seyler J. -P. Lorand H. J. B. Dick M. Drouin 《Contributions to Mineralogy and Petrology》2007,153(3):303-319
ODP Leg 209 Site 1274 mantle peridotites are highly refractory in terms of lack of residual clinopyroxene, olivine Mg# (up
to 0.92) and spinel Cr# (∼0.5), suggesting high degree of partial melting (>20%). Detailed studies of their microstructures
show that they have extensively reacted with a pervading intergranular melt prior to cooling in the lithosphere, leading to
crystallization of olivine, clinopyroxene and spinel at the expense of orthopyroxene. The least reacted harzburgites are too
rich in orthopyroxene to be simple residues of low-pressure (spinel field) partial melting. Cu-rich sulfides that precipitated
with the clinopyroxenes indicate that the intergranular melt was generated by no more than 12% melting of a MORB mantle or
by more extensive melting of a clinopyroxene-rich lithology. Rare olivine-rich lherzolitic domains, characterized by relics
of coarse clinopyroxenes intergrown with magmatic sulfides, support the second interpretation. Further, coarse and intergranular
clinopyroxenes are highly depleted in REE, Zr and Ti. A two-stage partial melting/melt–rock reaction history is proposed,
in which initial mantle underwent depletion and refertilization after an earlier high pressure (garnet field) melting event
before upwelling and remelting beneath the present-day ridge. The ultra-depleted compositions were acquired through melt re-equilibration
with residual harzburgites.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
18.
The state of the art of the problem of mantle melt transport through the upper mantle beneath spreading zones is reviewed. The geochemical data and physical properties of the mantle constraining the melt migration processes are considered. The review concentrates on the ways of mantle magma transport and mechanisms of the localization of diffuse intergranular porous melt percolation into the channel flow. The hypothesis of the reaction of migrating mantle magmas with wall peridotites and the formation of replacive dunites as a result of this process are discussed. We examine the publications on the field, theoretical, and geochemical studies of the reactive melt migration and its role in the dunite formation in the mantle sections of the ophiolites. Alternative models of the dunite origin in the mantle are also tested. The results of experimental studies of the melt/peridotite interaction are presented. 相似文献
19.
岩石钾质变化及钾交代与成矿关系 总被引：8，自引：0，他引：8
钾质高低及变化可反映岩石演化程度和钾交代作用。发生钾交代的岩石为成矿有利岩石和找矿标志。岩石钾交代与钾质升高归根于富碱的地幔流体活动。上升的地幔流体交代上地幔和地壳岩石形成富碱岩石和碱交代岩,并活化迁移不同围岩中成矿元素形成各种矿床。大地构造单元边缘与陆内张裂活动带是地幔流体交代活动场所和大型矿床形成地。许多矿床包括金矿床和钾交代关系密切。 相似文献
20.
山2段是鄂尔多斯盆地延安地区致密砂岩气生产的重要层段,目前对其流体赋存规律认识明显不足。因此在铸体薄片、扫描电镜、X射线衍射、高压压汞、恒速压汞、核磁共振测试的基础上,分析该储层可动流体的赋存特征及其影响因素。结果表明:山2储层主要为岩屑石英砂岩和岩屑砂岩,溶蚀孔和晶间孔为主要储集空间,粒间溶孔显著发育。山2储层可动流体饱和度为34.74%～91.83%,平均为69.94%,T2谱多为双峰态,呈左低右高型。储层孔隙度、渗透率、孔隙类型、孔喉特征及胶结物影响可动流体饱和度。孔隙为可动流体提供主要空间,平均孔隙半径越大,平均喉道半径越大,孔喉比越小,可动流体饱和度越高。硅质含量越高,粒间孔保存越好,可动流体饱和度越高。铁方解石含量越高,孔隙破坏越明显,可动流体饱和越低。高岭石含量较高,长石溶孔及晶间孔发育较好,有利于流体流动,可动流体饱和度也较高。 相似文献