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1.
江苏六合新生代玄武岩中地幔捕虏体的硫化物相研究 总被引：13，自引：3，他引：10
江苏六合一带碱性玄武岩中的出露有以尖晶石二辉橄榄岩为主的地幔捕虏体,这些地幔矿物中普遍有硫化物相出现：（１）被寄主矿物捕获的早期硫化物颗粒。（２）产于矿物晶粒边界或次生裂隙充填物,（３）硫化物包裹体,包括单相硫的包裹体、硫化物－玻璃两相熔体包裹体和ＣＯ／２－硫化物－玻璃（含硅酸盐子矿物）的多相包裹体,电子探针分析表明,硫化物包裹体比例隙中硫化物具有更高的相对Ｆｅ和Ｓ含量,较低的Ｎｉ含量。硫化物包裹 相似文献
2.
在亚库梯亚和南非的金刚石中广泛发育Ｆｅ－Ｎｉ－Ｃｕ硫化物的原生包裹体,对超基性岩和榴辉岩中金刚石的Ｆｅ－Ｎｉ－Ｃｕ－Ｓ系列包裹体进行了对比研究,结果表明,二者中的原始硫化物熔融体成分有明显差异,对金刚石及其共生矿物中硫化物包裹体的化学成分的研究相当全面,而对微量元素成分的研究还刚刚起步,对亚库梯亚金刚石（包括乌达奇内金伯利岩筒中的金刚石）的硫化物包裹体中混入元素成分进行了研究。其结果表明,超基性岩 相似文献
3.
地幔岩中流体包裹体研究 总被引：5，自引：2，他引：3
地幔岩石中的流体包裹体代表地幔流体的样品。地幔流体包裹体可以存在从地幔来的金刚石,地幔捕虏体和岩浆碳酸岩中。研究这些岩石和矿物中的流体包裹体可以得出其所代表的地幔流体的温度、压力、成分和同位素。我们目前见到的这三类地幔岩石的包裹体主要可在橄榄石、辉石、金刚石、方解石和磷灰石中见到。这些包裹体可以粗略地分为CO2包襄体和硅酸盐熔融体包裹体。又可细分为四类包裹体：（1）富碳酸盐的硅酸盐熔融包裹体。这种包裹体在金刚石、地幔岩捕虏体和岩浆碳酸盐岩中见到,它又可分为结晶质熔融包裹体和玻璃包裹体。（2）CO2包裹体。这种包裹体大多见于地幔捕虏体中,在金刚石和岩浆碳酸岩中也可见到。（3）含硫化物的包裹体。这种包裹体见于地幔捕虏体中,与纯CO2包裹体和含CO2的熔融包裹体共存。（4）高密度的流体包裹体。这种包裹体见于金刚石中,是一种高盐度、高密度的含K、Cl和H2O的流体包裹体,又可分为高卤水包裹体和含卤水的富硅的碳酸盐岩浆包裹体。从对金刚石、地幔捕虏体和岩浆碳酸盐岩中流体包裹体的研究表明,地幔流体存在不均匀性和不混溶性。 相似文献
4.
捕虏体麻粒岩是了解下地壳形成和演化的重要样品。汉诺坝新生代玄武岩中的二辉麻粒岩捕虏体样品中富含各种硫化物相，主要类型有：①孤立产出的球状出溶硫化物；②矿物颗粒之间或颗粒内的粗晶硫化物；③次生硫化物包裹体群；④裂隙充填硫化物。电子探针分析表明，硫化物的矿物成分均为贫镍磁黄铁矿，（Ni＋Co＋Cu）／Fe（原子比）远小于0．2；（Fe＋Cu＋Co＋Ni）／S（原子比）比地幔岩的磁黄铁矿小，多小于0．875，反映了一种S过饱和环境。各种产状的磁黄铁矿中Au、Ag都有一定的含量，其平均值分别为0．19％～0.22％（Au）、0．01％～0．02％（Ag），反映下地壳的麻粒岩化与金矿化的成因联系。磁黄铁矿的Ni、Co、Cu含量与S正相关，说明微量重金属元素与S具有同源的关系，由于地幔去气伴随S而进入下地壳。 相似文献
5.
萨拉林斯克金矿床的矿石属石英－硫化物型。黄铁矿中Ｎｉ、Ｃｏ、Ａｓ、Ａｇ和Ａｕ的含量范围很宽。它们的含量与Ｓ／Ｆｅ值呈规律性变化，说明它们以类质同象形式进入矿物结构中。查明了矿石含金性与黄铁矿成分的关系，并建立了矿体的结构模式。 相似文献
6.
西秦岭寒武系金矿床中硅岩的地质地球化学特征及其沉积环境意义 总被引：31，自引：4，他引：27
西秦岭寒武系中的硅岩是拉尔玛－邛莫层控金矿床的主要赋矿岩石之一。含矿硅岩呈块状、条带状、层纹状、多孔状和同生角砾状等。硅岩单层厚度一般为３０～２００ｍ。主要成分ＳｉＯ２平均含量高达９５．３０％,其余为ＦｅＯ、Ｆｅ２Ｏ３和有机炭等。硅岩的Ａｌ／（Ａｌ＋Ｆｅ＋Ｍｎ）比值低于０．３（平均０．１５３）,投点于Ｆｅ／Ｔｉ－Ａｌ／（Ａｌ＋Ｆｅ＋Ｍｎ）图解和Ａｌ－Ｆｅ－Ｍｎ三角图解上,均落于热水沉积物区。硅岩中微量元素十分丰富,不仅含有具基性、超基性特征的元素群（如Ｃｕ、Ｃｒ、Ｐｔ、Ｐｄ、Ｏｓ等）,而且还含有具酸性特征的元素群（如Ｗ、Ｍｏ、Ｕ等）。硅岩中稀土以总量（３．２９～１００μｇ／ｇ）低和铈亏损为特征。经北美页岩标准化后的稀土比值随原子序数的增大而增大。硅岩的δ１８Ｏ值为１７．６０‰～２３．２４‰,据此得到它形成的温度为７０．９℃～１１８．１℃。硅岩的δ３０Ｓｉ值主要为＋０．４‰～＋０．８‰。上述硅岩的特点均显示其与喷流热水沉积作用有关。硅岩中Ｐ２Ｏ５含量、Ｓｒ／Ｂａ比值、δＣｅ值以及δ３０Ｓｉ值表明,它主要是在深海—半深海环境下形成的。 相似文献
7.
地幔岩中不同产状的流体-熔体包裹体及地幔流体交代作用 总被引：1，自引：0，他引：1
地幔捕虏体中存在不同产状的熔体包裹体和各种硅酸盐玻璃相,包括主矿物内部的蠕虫状、长圆形、圆形、不规则状包裹体(I型)、边部的连通的管状包裹体(T型)、主矿物边部和粒间的片状熔融体——“浆胞”(C型),三者可见明显过渡关系,它们是地幔流体交代地幔岩石过程中由交代重熔形成的,是研究地幔流体的特征和地幔交代作用的对象之一,从I型、T型到C型,其成分呈规律变化,其中S、Cu、Ni,K、Na含量呈明显的降低趋势．包裹体中玻璃相的成分较主矿物富Si、Al、S、Cu、Ni、K和Na,再加上C02包裹体的发现,表明地幔流体的成分富碱金属、Si、Al、S、Cu、Ni和CO2,地幔交代作用可以使交代产物中Si、Al含量升高而形成中酸性岩浆,也可由于硫化物熔体聚集而形成矿浆．不同地区的地幔流体性质可能存在差异,这些不同性质的地幔流体町能与不同类型的地幔成矿作用有关． 相似文献
8.
地幔捕虏体中的流体-熔体包裹体 总被引：3，自引：0，他引：3
地幔流体的研究现已成为国内外前沿课题。地幔岩捕虏体中的流体-熔体包裹体是地幔流体的直接证据,通过对它们的研究可以直接获取地授流体的信息。包裹体按相态特征主要有三类：二氧化碳流体包裹体、二氧化碳-硅酸盐熔体包裹体、硫化物-熔体流体包裹体。本总结了地幔岩中流体-熔体包裹体的基本特征、微量元素地球化学、硫化物-熔体包裹体和二氧化碳流体包裹体稳定同位素特征的研究进展状况。讨论认为：地幔流体是由C、H、O、S等元素的挥发份和硅酸盐熔体组成;上地幔流体在化学成分上明显富含CO2、硫化物、LILE和BEE,它引起地幔交代作用和地授部分熔融;上地授流体的分布存在不均匀性,其组成也存在地区性差异。 相似文献
9.
本区金矿中黄铁矿的Ｍｏ谱测试和综合分析表明，主要穆斯堡尔参数的变化与含金性之间存在有一定的关系。主要表现为，黄铁矿的Ｉ．Ｓ．值与含金性间呈明显的负相关。Ｏ．Ｓ．值与含金性间则呈明显的正相关，且Ｏ．Ｓ．值随着（Ａｕ＋Ａｓ）／（Ｃｏ＋Ｎｉ）原子数比值的增大而增大。这是由于Ａｕ＋取代Ｆｅ２＋进入黄铁矿晶格使其结构产生畸变所致。置换时电荷补偿可通过两个途径来实现，其一是Ａｕ＋（Ｃｏ３＋、Ｎｉ３＋）→２Ｆｅ２＋，其二是Ａｓ３＋＋Ａｕ＋→２Ｆｅ２＋。 相似文献
10.
中国东南沿海地区地幔岩包体中流体及熔体包裹体研究 总被引：10，自引：1，他引：10
浙江新昌和福建明溪地区新生代玄武岩中地幔岩包体矿物中的ＣＯ２包裹体和含ＣＯ２硅酸盐岩浆包裹体的研究表明，它们捕获于温度１２０７℃～１２６７℃和压力８１５～１１４７ｍｐａ条件下，约相当于３０～５０ｋｍ深的上幔环境；ＣＯ２包裹体流体成分是以ＣＯ２为主，有ＣＨ４、ＣＯ、Ｈ２Ｓ、Ｈ２Ｏ、Ｎ２、和Ｈ２等次要组分，代表地幔流体成分。含ＣＯ２硅酸盐岩浆包裹体均一后成分不同于寄主玄武岩，它富ＳｉＯ２、Ａｌ２Ｏ３、ＭｇＯ和Ｋ２Ｏ，贫ＦｅＯ和ＣａＯ，反映了未分异原始玄武岩浆的成分，它们可能是研究地区的地幔软流圈－岩石圈界面抬升，压力降低在地幔流体作用下发生的部分熔融作用的产物． 相似文献
11.
Mantle xenoliths are common in the Cenozoic basalts of the Changbaishan District,Jilin Province,China.Sulfide assemblages in mantle minerals can be divided into three types:isolated sulfide grains,sulfide-meh inclusions and filling sulfides in fractures.Sulfide-meh inclusions occur as single-phase sulfides,sulfide-silicate melt,and CO_2-sulfide-silicate melt inclusions. Isolated sulfide grains are mainly composed of pyrrhotite,but cubanite was found occasionally.Sulfide-meh inclusions are mainly composed of pontlandite and MSS,with small amounts of chalcopyrite and talnakhite.The calculated distribution coefficient K_(D3)for lherzolite are similar to that of mean experimental value.The bulk sulfides in lherzolite were in equilibrium with the enclosing minerals, indicating immiscible sulfide melts captured in partial melting of upper mantle.Sulfide in fractures has higher Ni/Fe and(Fe Ni)/S than those of sulfide melt inclusions.They might represent later metasomatizing fluids in the mantle.Ni/Fe and(Fe Ni)/S increase from isolated grains,sulfide inclusions to sulfides in fractures.These changes were not only affected by temperature and pressure,hut by geochemistry of Ni,Fe and Cu,and sulfur fugacity as well. 相似文献
12.
Djerfisherite, a Cl-bearing potassium sulfide (K6Na(Fe,Ni,Cu)24S26Cl), is a widespread accessory mineral in kimberlite-hosted mantle xenoliths. Nevertheless, the origin of this sulfide in nodules remains disputable. It is usually attributed to the replacement of primary Fe–Ni–Cu sulfides when xenoliths interact with a K-and Cl-enriched hypothetical melt/fluid. The paper is devoted to a detailed study of the composition and morphology of djerfisherite from a representative collection (22 samples) of the deepest mantle xenoliths—sheared garnet peridotite, taken from the Udachnaya-East kimberlite pipe (Yakutia). Four types of djerfisherite were distinguished in the mantle rocks on the basis of morphology, spatial distribution, and relationships with the rock-forming and accessory minerals in the nodules. Type 1 was found in the rims of polysulfide inclusions in the rock-forming minerals of the xenoliths; there, it was younger than the primary sulfide assemblage pyrrhotite + pentlandite ± chalcopyrite. Type 2 formed rims around large polysulfide segregations (pyrrhotite+ pentlandite) in the xenolith interstices. Type 3 formed individual grains in the xenolith interstices together with other sulfides, silicates, oxides, phosphates, and carbonates. Type 4 was present as a daughter phase in the secondary melt inclusions which occurred in healed cracks in the rock-forming minerals of the xenoliths. Along with djerfisherite, the inclusions contained silicates, oxides, phosphates, carbonates, alkaline sulfates, chlorides, and sulfides. The results indicate that djerfisherite from the xenoliths is consanguine with kimberlite. Djerfisherite both in the sheared-peridotite xenoliths from the Udachnaya-East pipe and in different xenoliths from other kimberlite pipes worldwide formed owing to the interaction between the nodules and kimberlitic melts. Djerfisherite forming individual grains in the melt inclusions and xenolith interstices crystallized directly from the infiltrating kimberlitic melt. Djerfisherite bounding the primary Fe–Ni ± Cu sulfides formed by their replacement as a result of a reaction with the kimberlitic melt. 相似文献
13.
The composition of olivine and nickeliferous sulfide inclusions from a selection of mafic and ultramafre rocks, xenoliths and megacrysts, including picritic basalts from Kilauea Volcano, Hawaii, kimberlite from Fayette County, Pennsylvania, and megacrysts from Mount Shasta, California are compared with the mean experimental value of the distribution coefficient for Ni/Fe exchange (KD3=32). Only nine of the forty five olivipe/bulk-sulfide pairs investigated have compositions consistent with equilibration at high temperature, yielding calculated KD3 values in the range 22 to 41. The remaining pairs have calculated KD3 values which range from 0 to 19. Bulk-sulfides in disequilibrated assem-blages are consistently depleted in nickel and within both indivudual associations and individual petrographic sections they exhibit a wide variation in NiS content. The bulk copper contents of olivine-and groundmass-hosted sulfides from Kilauea Volcano range from 0.5 to 43 at%, and samples from the Kilauea Iki lava lake are more Fe-and Cu-rich and generally have lower KD3 values than those from the eruption itself. As with magmatic Ni–Cu sulfide deposits, most nickeliferous sulfide inclusions in mantle-related rocks and xenoliths and in volcanic rocks do not have pristine early-magmatic bulk compositions, and it would seem to be premature to attribute these sulfides solely to either a mantle or an early-magnatic origin. 相似文献
14.
捕虏体麻粒岩是了解下地壳形成和演化的重要样品。汉诺坝新生代玄武岩中的二辉麻粒岩捕虏体样品中富含各种硫化物相,主要类型有:①孤立产出的球状出溶硫化物;②矿物颗粒之间或颗粒内的粗晶硫化物;③次生硫化物包裹体群;④裂隙充填硫化物。电子探针分析表明,硫化物的矿物成分均为贫镍磁黄铁矿,(Ni+Co+Cu)/Fe(原子比)远小于0.2;(Fe+Cu+Co+Ni)/S(原子比)比地幔岩的磁黄铁矿小,多小于0.875,反映了一种S过饱和环境。各种产状的磁黄铁矿中Au、Ag都有一定的含量,其平均值分别为0.19%～0.22%(Au)、0.01%～0.02%(Ag),反映下地壳的麻粒岩化与金矿化的成因联系。磁黄铁矿的Ni、Co、Cu含量与S正相关,说明微量重金属元素与S具有同源的关系,由于地幔去气伴随S而进入下地壳。 相似文献
15.
Fluid inclusions in mantle xenoliths 总被引：23，自引：0，他引：23
Fluid inclusions in olivine and pyroxene in mantle-derived ultramafic xenoliths in volcanic rocks contain abundant CO2-rich fluid inclusions, as well as inclusions of silicate glass, solidified metal sulphide melt and carbonates. Such inclusions represent accidentally trapped samples of fluid- and melt phases present in the upper mantle, and are as such of unique importance for the understanding of mineral–fluid–melt interaction processes in the mantle. Minor volatile species in CO2-rich fluid inclusions include N2, CO, SO2, H2O and noble gases. In some xenoliths sampled from hydrated mantle-wedges above active subduction zones, water may actually be a dominant fluid species. The distribution of minor volatile species in inclusion fluids can provide information on the oxidation state of the upper mantle, on mantle degassing processes and on recycling of subducted material to the mantle. Melt inclusions in ultramafic xenoliths give information on silicate–sulphide–carbonatite immiscibility relationships within the upper mantle. Recent melt-inclusion studies have indicated that highly silicic melts can coexist with mantle peridotite mineral assemblages. Although trapping-pressures up to 1.4 GPa can be derived from fluid inclusion data, few CO2-rich fluid inclusions preserve a density representing their initial trapping in the upper mantle, because of leakage or stretching during transport to the surface. However, the distribution of fluid density in populations of modified inclusions may preserve information on volcanic plumbing systems not easily available from their host minerals. As fluid and melt inclusions are integral parts of the phase assemblages of their host xenoliths, and thus of the upper mantle itself, the authors of this review strongly recommend that their study is included in any research project relating to mantle xenoliths. 相似文献
16.
Dmitri A. Ionov Antoine Bénard Pavel Y. Plechov 《Contributions to Mineralogy and Petrology》2011,162(6):1159-1174
Glass-bearing inclusions hosted by Cr-spinel in harzburgite xenoliths from Avacha are grouped based on homogenization temperatures
and daughter minerals into high-T (1,200°C; opx + cpx), intermediate (900–1,100°C; cpx ± amph), and low-T (900°C; amph) and
are commonly accompanied by larger “melt pockets”. Unlike previous work on unheated inclusions and interstitial glass in xenoliths
from Kamchatka, the homogenized glass compositions in this study are not affected by low-pressure melt fractionation during
transport and cooling or by interaction with host magma. Primary melt compositions constrained for each inclusion type differ
in major and trace element abundances and were formed by different events, but all are silica saturated, Ca-rich, and K-poor,
with enrichments in LREE, Sr, Rb, and Ba and negative Nb anomalies. These melts are inferred to have been formed with participation
of fluids produced by dehydration of slab materials. The high-T inclusions trapped liquids produced by ancient high-degree,
fluid-induced melting in the mantle wedge. The low-T inclusions are related to percolation of low-T melts or hydrous fluids
in arc mantle lithosphere. Melt pockets arise from localized heating and fluid-assisted melting induced by rising magmas shortly
before the entrapment of the xenoliths. The “high-T” melt inclusions in Avacha xenoliths are unique in preserving evidence
of ancient, high-T melting events in arc mantle, whereas the published data appear to characterize pre-eruption enrichment
events. 相似文献
17.
地幔流体作用——地幔捕虏体中流体包裹体的研究 总被引：8，自引：0，他引：8
被碱性玄武岩和金伯利岩带到地表的地幔捕虏体是认识地球深部信息的窗口 ,是人们能够直接观察到的一种上地幔样品 ,其矿物中流体包裹体的存在提供了上地幔流体活动的直接证据。流体 /地幔矿物之间元素的分配对约束地幔交代过程中流体相的作用和上地幔流体的组成 ,揭示俯冲带壳幔物质的再循环过程 ,解释岛弧玄武岩高场强元素亏损的原因有重要意义。文章对近年来有关地幔捕虏体中流体包裹体的研究进行了评述 ,并结合近年来流体 /地幔矿物之间元素分配的高温高压实验研究讨论了流体在地幔中的重要作用。 相似文献