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1.
Abstract Spinel lherzolite is a minor component of the deep-seated xenolith suite in the Oki-Dogo alkaline basalts, whereas other types of ultramafic (e.g. pyroxenite and dunite) and mafic (e.g. granulite and gabbro) xenoliths are abundant. All spinel lherzolite xenoliths have spinel with a low Cr number (Cr#; < 0.26). They are anhydrous and are free of modal metasomatism. Their mineral assemblages and microtextures, combined with the high NiO content in olivine, suggest that they are of residual origin. But the Mg numbers of silicate minerals are lower (e.g. down to Fo86 ) in some spinel lherzolites than in typical upper mantle residual peridotites. The clinopyroxene in the spinel lherzolite shows U-shaped chondrite-normalized rare-earth element (REE) patterns. The abundance of Fe-rich ultramafic and mafic cumulate xenoliths in Oki-Dogo alkali basalts suggests that the later formation of those Fe-rich cumulates from alkaline magma was the cause of Fe- and light REE (LREE)-enrichment in residual peridotite. The similar REE patterns are observed in spinel peridotite xenoliths from Kurose and also in those from the South-west Japan arc, which are non-metasomatized in terms of major-element chemistry (e.g. Fo > 89), and are rarely associated with Fe-rich cumulus mafic and ultramafic xenoliths. This indicates that the LREE-enrichment in mantle rocks has been more prominent and prevalent than Fe and other major-element enrichment during the metasomatism. 相似文献
2.
地幔橄榄岩矿物中富稀土元素的CO2流体包裹体及其地球化学意义 总被引：18，自引：2，他引：18
五个无水尖晶石橄榄岩（两个富含ＣＯ２流体包裹体，三个含ＣＯ２流体包裹体）的全岩和单矿物稀土元素中子活化分析结果，证实了ＬＲＥＥ在ＣＯ２流体包裹体中富集。富含ＣＯ２流体包裹体的全岩，斜方辉石和单斜辉石比相应不含ＣＯ２流体包裹体的，其ＬＲＥＥ分别高出１１倍，５９倍和３２倍。前是在经历了较大程度部分熔融之后的亏损地幔，又受富ＣＯ２流体的强烈交代作用。后刚为经历低程度熔融作用与富集过程，并可能导致地幔 相似文献
3.
Yue‐Heng Yang Fu‐Yuan Wu Qiu‐Li Li Yamirka Rojas‐Agramonte Jin‐Hui Yang Yang Li Qian Ma Lie‐Wen Xie Chao Huang Hong‐Rui Fan Zi‐Fu Zhao Cheng Xu 《Geostandards and Geoanalytical Research》2019,43(4):543-565
Bastnäsite is the end member of a large group of carbonate–fluoride minerals with the common formula (REE) CO3F·CaCO3. This group is generally widespread and, despite never occurring in large quantities, represents the major economic light rare earth element (LREE) mineral in deposits related to carbonatite and alkaline intrusions. Since bastnäsite is easily altered and commonly contains inclusions of earlier‐crystallised minerals, in situ analysis is considered the most suitable method to measure its U‐Th‐Pb and Sr‐Nd isotopic compositions. Electron probe microanalysis and laser ablation (multi‐collector) inductively coupled plasma‐mass spectrometry of forty‐six bastnäsite samples from LREE deposits in China, Pakistan, Sweden, Mongolia, USA, Malawi and Madagascar indicate that this mineral typically has high Th and LREE and moderate U and Sr contents. Analysis of an in‐house bastnäsite reference material (K‐9) demonstrated that precise and accurate U‐Th‐Pb ages could be obtained after common Pb correction. Moreover, the Th‐Pb age with its high precision is preferable to the U‐Pb age because most bastnäsites have relatively high Th rather than U contents. These results will have significant implications for understanding the genesis of endogenous ore deposits and formation processes related to metallogenic geochronology research. 相似文献
4.
《International Geology Review》2012,54(1):115-130
We acquired bulk-rock analyses of Mid-Atlantic Ridge (MAR) harzburgites in order to understand the influence of submarine igneous and metamorphic processes on the distribution of incompatible elements (especially rare Earth elements or REEs) in abyssal peridotites. The geochemical characteristics of these Logatchev Massif serpentinized and talc-altered harzburgites, and spatially associated metagabbros were then compared with a compilation of global abyssal peridotites. The Logatchev harzburgites show light rare earth element (LREE) enrichments (average La N /Yb N = 2.81), positive correlations between LREEs (e.g. La, Ce, Pr, and Nd) and high field strength elements (HFSEs; e.g. Nb and Zr), and positive correlations between HFSEs and Th. Most global abyssal peridotites show similar trends. We suggest that the systematic enrichment of incompatible elements probably reflects a post-partial fusion magmatic refertilization. The compositional scatter exhibited by some serpentinized peridotites in Nb-LREE diagrams is probably due to the elimination of diopside during partial melting and significant impregnation by a melt produced in the Opx–Ol–Sp melting field rather than to later hydrothermal alteration. The correlation between Pb and Nd observed for most global abyssal peridotites, including the Logatchev harzburgites, indicates magmatic generation. The scatter of Pb in some rocks suggests that lead is likely mobile during serpentinization or weathering. Low to moderate water/rock (W/R) ratios in the harzburgites calculated from Sr isotopic compositions (5.98–26.20 for a close system and 1.66–2.72 for an open system), and the low abundance of REEs in Logatchev hydrothermal fluids indicate that the REE contents of abyssal peridotites probably were little influenced by hydrothermal alteration. Compared to this later alteration, the presence of small proportions of gabbroic melt (from 1:30 to 1:3 in our sample) that crystallized in the residual harzburgites modified their REE patterns significantly by elevating the LREEs. 相似文献
5.
S, C, O, H Isotope Data and Noble Gas Studies of the Maoniuping LREE Deposit, Sichuan Province, China： A Mantle Connection for Mineralization 总被引：3，自引：2，他引：1
TIAN Shihong DING Tiping MAO Jingwen LI Yanhe YUAN Zhongxin Institute of Mineral Resources Chinese Academy of Geological Sciences Beijing Key Laboratory of Isotope Geology Ministry of Land Resources Beijing China University of Geosci 《《地质学报》英文版》2006,80(4):540-549
The Maoniuping REE deposit, located about 22 km to the southwest of Mianning, Sichuan Province, is the second largest light REE deposit in China, subsequent to the Bayan Obo Fe-Nb-REE deposit in the Inner Mongolia Autonomous Region. Tectonically, it is located in the transitional zone between the Panxi rift and the Longmenshan-Jinpingshan orogenic zone. It is a carbonatite vein-type deposit hosted in alkaline complex rocks. The bastnaesite-barite, bastnaesite-calcite, and bastnaesite-microcline lodes are the main three types of REE ore lodes. Among these, the first lode is distributed most extensively and its REE mineralization is the strongest. Theδ34Sv-CDT values of the barites in the ore of the deposit vary in a narrow range of +5.0 to +5.1‰in the bastnaesite-calcite lode and +3.3 to +5.9‰in the bastnaesite-barite lode, showing the isotopic characteristics of magma-derived sulfur. Theδ13Cv-PDB values and theδ518OV-SMOW values in the bastnaesite-calcite lode range from -3.9 to -6.9‰and from +7.3 to +9.7‰, respectively, which fall into the range of "primary carbonatites", showing that carbon and oxygen in the ores of the Maoniuping deposit were derived mainly from a deep source. Theδ13Cv-PDB values of fluid inclusions vary from -3.0 to -5.6‰, with -3.0 to -4.0‰in the bastnaesite-calcite lode and -3.0 to -5.6‰in the bastnaesite-barite lode, which show characteristics of mantle-derived carbon. TheδDv-SMOW values of fluid inclusions range from -57 to -88‰, with -63 to -86‰in the bastnaesite-calcite lode and -57 to -88‰in the bastnaesite-barite lode, which show characteristics of mantle-derived hydrogen. Theδ18OH2OV-SMOW values vary from +7.4 to +8.6‰in the bastnaesite calcite lode, and +6.7 to +7.8‰in the bastnaesite-barite lode, almost overlapping the range of +5.5 to +9.5‰for magmatic water. The 4He content, R/Ra ratios are (13.95 to 119.58×10-6 (cm3/g)STP and 0.02 to 0.11, respectively, and 40Ar/36Ar is 313±1 to 437±2. Considering the 4He increase caused by high contents of radioactive elements, a mantle-derived fluid probably exists in the inclusions in the fluorite, calcite and bastnaesite samples. The Maoniuping deposit and its associated carbonatite-alkaline complex were formed in 40.3 to 12.2 Ma according to K-Ar and U-Pb data. All these data suggest that large quantities of mantle fluids were involved in the metallogenic process of the Maoniuping REE deposit through a fault system. 相似文献
6.
矾山磷铁矿床稀土元素地球化学特征 总被引：3，自引：0，他引：3
矾山磷铁矿床赋存于矾山杂岩体内 ,呈层状产出 ,是由深源富钾铁镁质岩浆演化而形成的晚期矿床。矾山杂岩体由三期侵入岩和脉岩组成 ,矿床产于第一期侵入岩中。第一期侵入岩较其它期次侵入岩REE含量高 ,按辉石岩—黑云母辉石岩—磷灰石岩的顺序增加。矿床稀土元素地球化学特征及主要元素含量表明 :在岩桨演化晚期 ,在贫硅和缺少足够“Ca2 +”的条件下 ,稀土元素极易代替“Ca2 +”而进入磷灰石晶格形成补尝类质同象。这对于研究矿床形成的物理化学环境和岩桨的演化具有重要意义。 相似文献
7.
Relationship between light rare earth deposits and mantle processes in Panxi rift, China 总被引：3，自引：0，他引：3
Many light rare earth deposits, such as Maoniuping, Dalucao, Panzhihua deposits, are collectively distributed in Panxi rift of Sichuan Province, China, and closely associated with the aegirine quartz syenite-carbonatite complex. Carbon and oxygen isotope studies demonstrate that the carbonatites in the complex are of typical igneous origin related to mantle processes. Electronic microprobe studies show that the fluid-melt inclusions found in the complex are enriched in light rare earth elements (LREE), which suggests that the magma was rich in LREE and could serve as the ore source for the regional LREE mineralization. Both the aegirine quartz syenite-carbonatite complex and the LREE mineralization found therein were derived from the mantle. The rare gas isotope analyses also support that there is a genetic association between the LREE mineralization and mantle processes. 相似文献
8.
J. J. Kasper-Zubillaga A. Carranza-Edwards O. Morton-Bermea 《Marine Georesources & Geotechnology》2013,31(3):172-188
A heavy mineral (HM) study and light and heavy rare earth elements (LREE and HREE) analysis were performed in coastal and inland dune sands, El Vizcaino Desert, Central Baja California Peninsula, Mexico. Our study shows high abundances of hornblende and apatite in the El Vizcaino dune sands, suggesting a dominance of granodiorites/intermediate plutonic rocks and marine authigenic phosphorite in the dune sands. There is a relationship between unstable heavy minerals like hornblende, pyroxenes, and sphene, and heavy rare earth elements (HREE) that suggests that unstable heavy minerals are potential carriers of HREE in the dune fields. However, there is a slight depletion of HREE in relation to LREE, especially in one locality of the inland dunes probably associated with the wind regime and weathering of unstable heavy minerals in the sands. Inland, transitional, and coastal dune fields can be observed as different dune provinces by means of grouping HM and REE data in two separate dendograms. It seems that HREE are correlated with fine-grained sand sizes and correlated with high CIA values linked to slightly weathered sands. 相似文献
9.
Arkadiusz Przybyło Anna Pietranik Grzegorz Zieliński 《Chemie der Erde / Geochemistry》2022,82(2):125864
Apatite is a versatile mineral crystallizing at different stages of silicic magma evolution. Its composition may record that of magma, but could also be affected by interaction with fluids. The focus of this study is the well-recognized magma mingling process that was previously detected using plagioclase composition and in this study complementary record is sought in apatite. The apatite was analysed in two dioritic enclaves (primitive and hybrid) and host quartz monzonite, which is an igneous rock emplaced at ca. 340 Ma in mylonitized Góry Sowie gneisses (NE Bohemian Massif). The apatite was analysed in-situ by microprobe that allowed for chemical characterization of different apatite populations in quartz monzonite and analyses of thin acicular apatite in the enclaves. Apatite population in the quartz monzonite was chemically distinct from that in both enclave types and characterized by higher Y and lower Ce contents, such values are usually typical for peraluminous magmas. As such, the apatite transfer from felsic to mafic magma should be well recorded in apatite composition, which was not the case. Monzonite apatite composition was not commonly observed in the hybrid enclave despite massive plagioclase transfer and only rare resorbed cores with low Ce and Y contents were present. However, such low Ce and Y cores crystalized at the latest stage of apatite crystallization in the quartz monzonite, whereas the plagioclase transfer was an early episode. Therefore, we conclude that apatite transfer was limited during mingling and the apatite composition in the quartz monzonite is best explained by an early Cl-Ce-rich fluid removal and then fractional crystallization, while apatite in the primitive enclave is affected only by fractional crystallization. Altogether, Ce and Y composition of apatite is a valuable tool to record diverse magmatic processes such as fluid removal and precipitation from fluid in addition to fractionation of different REE phases and should be further explored. 相似文献
10.