获得塔里木盆地北缘辛格尔灰色片麻岩的可靠形成年龄对研究塔里木克拉通地壳构造演化是十分重要的。本研究应用SIMS锆石U-Pb定年，获得了塔里木北缘辛格尔南托格拉克布拉克杂岩中占主要成分的灰色片麻岩的形成年龄为2565±18（2d）M...获得塔里木盆地北缘辛格尔灰色片麻岩的可靠形成年龄对研究塔里木克拉通地壳构造演化是十分重要的。本研究应用SIMS锆石U-Pb定年，获得了塔里木北缘辛格尔南托格拉克布拉克杂岩中占主要成分的灰色片麻岩的形成年龄为2565±18（2d）Ma，这一研究结果说明丁辛格尔地区的灰色片麻岩和库鲁克塔格中部的蓝石英花岗岩等均为新太古代晚期形成的TTG组份的岩浆岩。综合已有的研究结果，如灰色片麻岩中以残留包体形式存在的斜长角闪岩的Sm．Nd等时线年龄=3263±126Ma（2σ），εNd（t）=＋3．2±0．7（Huet al，1992），以及塔里木北缘范围内各种片麻岩、片岩和各种花岗岩的Nd模式年龄（TDM）分布在3200～2600Ma范围内（冯新昌等，1998；董富荣等，1999；Hu et al．，2000），完全可以确认塔里木盆地北缘普遍存在中一新太占代基底。但是，它们遭受了古元古代构造、变质和岩浆活动的强烈改造。辛格尔灰色片麻岩中～2300Ma、～2000Ma和片麻状花岗岩的～2000Ma锆石U-Pb年龄（高振家等，1993；郭召杰等，2003），以及铁门关斜长角闪岩中的锆石U-Pb年龄～1800Ma（郭召杰等，2003）等，就是两次重要构造热事件的记录。K-Ar年龄同样揭示塔里木盆地北缘新元古代至早古生代时期的地质热事件，^40At／^39Ar坪年龄或激光微区^40Ar/^39Ar等时线年龄等对该区变质岩中角闪石、黑云母及白云母的研究结果表明，塔里木北缘在大约850～500Ma期间，表现为各地段不均一整体性构造隆升（胡霭琴等，出版中）。展开更多
The Neo-Archean Sonakhan Greenstone Belt(SGB) located in the north-eastern fringes of Bastar craton,Central India, is dominated by Basalts, Andesites, Dacites and Rhyolites association. Partial melting modeling on the...The Neo-Archean Sonakhan Greenstone Belt(SGB) located in the north-eastern fringes of Bastar craton,Central India, is dominated by Basalts, Andesites, Dacites and Rhyolites association. Partial melting modeling on the SGB metabasalts indicates that these rocks were derived by20% melting of spinel peridotite. Fractional crystallisation modeling with REE reveal that the most evolved samples represent the product of fractional crystallization of least evolved magma with 35% plagioclase, 35% clinopyroxene,20% olivine, 5% magnetite and 5% ilmenite as fractionating minerals with 40% remaining magma. Depletion of HFSE with reference to the LILE and LREE/HFSE ratios and Nb, Zr anomalies in the multi-element diagram of the mafic rocks of SGB indicate Island arc magmatic setting.The enriched Th/Yb values further substantiate that the mantle arrays were modified by subduction-related fluids or melts. The general conclusions drawn indicate that the metabasalts from the SGB were formed as a result of subduction of an intraoceanic lithosphere in a fore-arc suprasubduction zone environment.展开更多
文摘获得塔里木盆地北缘辛格尔灰色片麻岩的可靠形成年龄对研究塔里木克拉通地壳构造演化是十分重要的。本研究应用SIMS锆石U-Pb定年，获得了塔里木北缘辛格尔南托格拉克布拉克杂岩中占主要成分的灰色片麻岩的形成年龄为2565±18（2d）Ma，这一研究结果说明丁辛格尔地区的灰色片麻岩和库鲁克塔格中部的蓝石英花岗岩等均为新太古代晚期形成的TTG组份的岩浆岩。综合已有的研究结果，如灰色片麻岩中以残留包体形式存在的斜长角闪岩的Sm．Nd等时线年龄=3263±126Ma（2σ），εNd（t）=＋3．2±0．7（Huet al，1992），以及塔里木北缘范围内各种片麻岩、片岩和各种花岗岩的Nd模式年龄（TDM）分布在3200～2600Ma范围内（冯新昌等，1998；董富荣等，1999；Hu et al．，2000），完全可以确认塔里木盆地北缘普遍存在中一新太占代基底。但是，它们遭受了古元古代构造、变质和岩浆活动的强烈改造。辛格尔灰色片麻岩中～2300Ma、～2000Ma和片麻状花岗岩的～2000Ma锆石U-Pb年龄（高振家等，1993；郭召杰等，2003），以及铁门关斜长角闪岩中的锆石U-Pb年龄～1800Ma（郭召杰等，2003）等，就是两次重要构造热事件的记录。K-Ar年龄同样揭示塔里木盆地北缘新元古代至早古生代时期的地质热事件，^40At／^39Ar坪年龄或激光微区^40Ar/^39Ar等时线年龄等对该区变质岩中角闪石、黑云母及白云母的研究结果表明，塔里木北缘在大约850～500Ma期间，表现为各地段不均一整体性构造隆升（胡霭琴等，出版中）。
文摘The Neo-Archean Sonakhan Greenstone Belt(SGB) located in the north-eastern fringes of Bastar craton,Central India, is dominated by Basalts, Andesites, Dacites and Rhyolites association. Partial melting modeling on the SGB metabasalts indicates that these rocks were derived by20% melting of spinel peridotite. Fractional crystallisation modeling with REE reveal that the most evolved samples represent the product of fractional crystallization of least evolved magma with 35% plagioclase, 35% clinopyroxene,20% olivine, 5% magnetite and 5% ilmenite as fractionating minerals with 40% remaining magma. Depletion of HFSE with reference to the LILE and LREE/HFSE ratios and Nb, Zr anomalies in the multi-element diagram of the mafic rocks of SGB indicate Island arc magmatic setting.The enriched Th/Yb values further substantiate that the mantle arrays were modified by subduction-related fluids or melts. The general conclusions drawn indicate that the metabasalts from the SGB were formed as a result of subduction of an intraoceanic lithosphere in a fore-arc suprasubduction zone environment.
