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苏北踢球山榴辉岩演化的同位素年代学证据 总被引:1,自引:0,他引:1
采用Sm Nd同位素定年方法 ,测得江苏北部新沂地区踢球山三个榴辉岩岩体时代为 :2 2 1.6± 8.4Ma ,2 13.6± 9.2Ma和 2 16 .6± 8.1Ma;εNd(t)分别为 - 2 .9,- 2 .9和 - 3.0。采用Rb Sr定年方法得到其中一个榴辉岩的年龄为 2 0 1± 2 1Ma ;87Sr/ 86Sr =0 .70 5 35± 37。Sm Md年龄被看作为踢球山超高压变质之后板块折返过程中的高压榴辉岩相重结晶阶段年龄。Rb Sr年龄反映了踢球山榴辉岩体的板块折返过程中的角闪岩相退变质阶段开始年龄。为中朝板块与扬子板块碰撞时代主要发生在晚三叠世的观点提供了依据 相似文献
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新疆东天山西段却勒塔格蛇绿岩地球化学特征 总被引:3,自引:4,他引:3
新疆东天山西段乌什通沟—干沟蛇绿混杂岩带分布在干沟断裂南侧,该断裂是准噶尔板块与塔里木板块的分界面,该断裂北侧却勒塔格蛇绿岩围岩为古元古界变质深成岩(Sm-Nd全岩等时年龄(1 859±66)Ma)及白云岩、白云质大理岩、石墨大理岩和变质火山岩等.却勒塔格蛇绿岩以构造包体形式赋存在古变质岩中,镁铁质超基性岩具高Mg,贫Al、Ca、K、Na的特点,属阿尔卑斯型高钛蛇绿岩组合,形成时代为中晚震旦世(辉长岩Sm-Nd全岩等时年龄(728±110)Ma),闭合时代为中晚奥陶世.却勒塔格蛇绿岩和前震旦古变质岩的发现,具有重大地质意义。 相似文献
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湖南益阳早前寒武纪镁铁质-超镁铁质火山岩的Sm-Nd同位素年龄 总被引:6,自引:0,他引:6
益阳地区出露的似层状 -层状镁铁质 -超镁铁质火山岩的时代归属有不同的观点。研究认为其主要岩石类型为玄武质科马提岩和拉斑玄武岩。岩石地球化学和同位素年龄显示 :玄武质科马提岩 Sm-Nd全岩等时线年龄为 ( 3 0 2 8± 47) Ma,属中、新太古代洋中脊 -岛弧火山岩 ;拉斑玄武岩年龄为 ( 2 2 1 6± 3 8) Ma,属古元古代。这一结果揭示了早前寒武纪在古扬子微板块(川中微板块 )东南有多岛弧洋盆 ,湖南深部地壳有绿岩基底。 相似文献
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中国滇西南造山带变质岩的Sm-Nd和Rb-Sr同位素年代学 总被引:12,自引:11,他引:12
滇西南造山带的主体由多期变质的岩石单元组成。变质和变形年代的确定是研究它们构造演化的关键之一。哀牢山群和大勐龙群斜长角闪岩分别得到1367Ma和1436Ma的Sm-Nb等时线年龄,这代表了高级角闪岩相的变质时代。它们的形成年龄约为2000~1600Ma。崇山群黑云斜长片麻岩获得了与此相当的1900~1600Ma的Sm-Nd模式年龄。澜沧群的蓝片岩的Sm-Nd等时线年龄为1287Ma,绿片岩的Sm-Nd模式年龄为1300~1200Ma。上述各组岩石还获得了约为1000Ma、500~400Ma、300~180Ma和180~140Ma的几组Rb-Sr等时线或Sm-Nd和Rb-Sr模式年龄,分别代表了后期重要构造事件。 相似文献
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北大别洪庙榴辉岩相岩石Sm-Nd年龄:峰期变质时代 总被引:1,自引:1,他引:0
前人工作认为北大别榴辉岩在榴辉岩相变质后,经历了麻粒岩相退变质作用,因此获得的Sm-Nd矿物等时线年龄代表了麻粒岩相变质时代.本文对北大别安徽洪庙百丈岩榴辉岩相岩石(辉石石榴石岩)的研究表明,该岩石经历了三叠纪超高压变质作用,经历了角闪岩相退变质.所研究样品在峰期变质之后是否经历了麻粒岩相退变质尚不能明确界定.结合矿物氧同位素体系平衡判据,辉石石榴石岩在峰期变质时达到了Sm-Nd同位素体系的均一化和平衡,并且在后期角闪岩相退变质中该同位素体系未出现明显的扰动,因此其Sm-Nd矿物等时线年龄[(225±14)Ma和(229±13)Ma]代表了榴辉岩相变质时代.同时,样品中矿物的同位素组成表明,在俯冲板块折返和退变质过程中,岩石受到外来和内部流体的不均匀作用,造成退变的单斜辉石在同位素组成上的不均一. 相似文献
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对丹巴地区广泛分布的志留系、泥盆系和三叠系地层进行了较系统的Sm-Nd同位素研究。这些变质沉积岩的地壳存留年龄为2284-1977Ma,它介于扬子板块核部晚太古代地壳(2900-2600Ma)和板块边缘中-新元古代地壳(1180-812Ma)之间,表明丹巴地区的古生代地层可能主要是这两个物源区按一定比例均匀混合的产物。 相似文献
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海南岛屯昌玄武质科马提岩成岩时代一直未获解决。作者利用Sm-Nd同位素法测试了5件样品,获得岩石Sm-Nd同位素等时线年龄1687±10Ma,及与其相近的Nd模式年龄1637-1756Ma。同时获得了钕同位素初始比值INd=0.510796±0.000006(2σ),εNd(T)=+6.64。表明玄武质科马提岩结晶年龄为古元古代(1687Ma),反映了海南岛在古元古时期的壳-幔分异与地壳增生的重要过程。 相似文献
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Gilles Serge Odin 《Comptes Rendus Geoscience》2002,334(6):409-414
Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414. 相似文献
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正1 Introduction Geological studies established on several sections in Lanping-Simao basin have shown that the salt-bearing strata of Mengyejing formation(Yunlong Fm.in Lanping basin)are constituted by an alternation of salt layers and interbedded facies.The latter consists mainly of mudstones,and mudstone-rich conglomerate.The mineralogy and geochemistry of salt-bearing beds and 相似文献
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正On 22nd April 2014,with the approach of the 45th World Earth Day,China’s Ministry of Land and resources issued the status of China’s mineral resources in 2013.The first task of the prospecting breakthrough strategy action implemented in the last five years has been completed,and China’s security capacity for mineral resources has been significantly improved.In the 相似文献
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正There are more than 700 salt lakes with area of more than 1km2 on the Qinghai-Tibet Plateau of China.In recent years,an oilfield brine was also found in the Nanyishan Section of Qaidam Basin in the Qinghai-Tibet 相似文献
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正1 Introduction Physical and numerical models are constructed to investigate the evolution and mechanism of salt migration driven by tectonic processes.In recent years,we have designed and ran series of models to simulate salt 相似文献
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YUAN Qin LI Jianguo QIN Zhanjie WEI Haicheng SHENG Shurong SHAN Fashou 《《地质学报》英文版》2014,88(Z1):276-276
正The study of Cretaceous-Palaeogene salt-bearing strata of the Khorat Basin Laos and the Lanping-Simao Basin in Yunnan,China has an great significance not only in explaining the basin evolution and the genesis of potash 相似文献
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正Potash is one of the long-term scare deposits in China,and potash prospecting has long been listed as a key brainstorm project for our nation and geological prospecting units.There have been considerable studies in search for potash deposits in the Kuqa depression of the Tarim basin(Jackson et al.,1991;Gemmer et al.,2004;Vendeville,2005;Vendeville and Jackson,1992a,1992b), 相似文献
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正1 Introduction Qaidam Basin in Qinghai,including 43 salt lakes with multiple dominant mineral such as potassium,magnesium,lithium etc.,is the most intensive distribution of Saline 相似文献