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| 俄罗斯Chukchi半岛新生代碱性岩的形成和演化：熔体和流体包裹体证据 | |
| 作者姓名： | IrinaP.Solovova Theodoros Ntaflos Andrei Girnis Natalya N.Kononkova Vyacheslav V.Akinin |
| 作者单位： | Institute of Geology of Ore Deposits Petrography，Mineralogy，and Geochemistry，35 Staromonetny，Moscow，119017，Russia，Institute of Mineralogy，University of Vienna，Austria，Institute of Geology of Ore Deposits，Petrography，Mineralogy，and Geochemistry，35 Staromonetny，Moscow，119017，Russia，Vernadsky Institute of Geochemistry and Analytical Chemistry，Moscow，Russia，Northeastern Interdisciplinary Research Institute，Magadan，Russia |
| 基金项目： | This study was financially supported by the Russian Foundation for Basic Research and Russian Program for the Support of Leading Scientific Schools. |
| 摘 要： | Melt and fluid inclusions were studied in the minerals of Cenozoic olivine melanephelinites from the Chukchi Peninsula, Russia.The rock contain several generations of olivine phenocrysts varying in composition at mg=0.88～0.77.The phenocrysts bear fluid and melt inclusions recording various stages of melt crystallization in volcanic conduits and shallow magma chambers.Primary fluid inclusions are CO_2-dominated with a density of up to O.93 g/cm~3.All fluid inclusions are partially leaked,which is indicated by haloes of tiny fluid bubbles around large fluid inclusions in minerals.Melt inclusions contain various daughter crystals,which were completely resorbed in thermometric experiments at about 1230℃.Assuming that this temperature corresponds to the entrapment conditions of the CO_2 fluid inclusions,the minimum pressure of the beginning of magma degassing is estimated as 800MPa.Variations in the compositions of homogenized silicate melt inclusions indicate that olivine was the earliest crystalline phase followed by clinopyroxene,nepheline and orthoclase.This sequence is in agreement with the mineralogy of the rocks.The melts are strongly enriched in incompatible trace elements and volatiles(in addition to CO_2,high C1,F,and S contents were detected).There are some differences between the compositions of melts trapped in minerals from different samples.Variations in SiO_2,FeO,and incompatible element contents are probably related to melt generations at various levels in a homogeneous mantle reservoir. |
| 关 键 词： | 俄罗斯Chukchi半岛 新生代 碱性岩 形成 演化 熔体 流体包裹体 |
| 文章编号： | 1000-0569/2007/023（01）-0083-92 |
| 修稿时间： | 2006-07-12 |
Generation and evolution of Cenozoic alkaline rocks from the Chukchi peninsula, Russia: Insight from melt and fluid inclusions |
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| IrinaP.Solovova Theodoros Ntaflos Andrei Girnis Natalya N.Kononkova Vyacheslav V.Akinin.Generation and evolution of Cenozoic alkaline rocks from the Chukchi peninsula, Russia: Insight from melt and fluid inclusions[J].Acta Petrologica Sinica,2007,23(1):83-92. | |
| Authors: | Irina P Solovov Theodoros Ntaflos Andrei Girnis Natalya N Kononkov Vyacheslav V Akinin |
| Institution: | 1. Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry, 35 Staromonetny, Moscow, 119017, Russia 2. Institute of Mineralogy, University of Vienna, Austria 3. Vernadsky Institute of Geochemistry and Analytical Chemistry, Moscow, Russia 4. Northeastern Interdisciplinary Research Institute, Magadan, Russia |
| Abstract: | Melt and fluid inclusions were studied in the minerals of Cenozoic olivine melanephelinites from the Chukchi Peninsula, Russia. The rock contain several generations of olivine phenocrysts varying in composition at mg= 0.88 ～ 0.77. The phenocrysts bear fluid and melt inclusions recording various stages of melt crystallization in volcanic conduits and shallow magma chambers. Primary fluid inclusions are CO2-dominated with a density of up to 0.93 g/cm3. All fluid inclusions are partially leaked, which is indicated by haloes of tiny fluid bubbles around large fluid inclusions in minerals. Melt inclusions contain various daughter crystals, which were completely resorbed in thermometric experiments at about 1230℃. Assuming that this temperature corresponds to the entrapment conditions of the CO2 fluid inclusions, the minimum pressure of the beginning of magma degassing is estimated as 800MPa. Variations in the compositions of homogenized silicate melt inclusions indicate that olivine was the earliest crystalline phase followed by clinopyroxene, nepheline and orthoclase. This sequence is in agreement with the mineralogy of the rocks. The melts are strongly enriched in incompatible trace elements and volatiles (in addition to CO2, high Cl, F, and S contents were detected). There are some differences between the compositions of melts trapped in minerals from different samples. Variations in SiO2, FeO, and incompatible element contents are probably related to melt generations at various levels in a homogeneous mantle reservoir. |
| Keywords: | Chukchi Peninsula Melanephelinite Inclusion Melt Fluid |
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