岩石标准物质的研制     

(Institute of Rock  Mineral Analysis  Ministry of geology  mineral Resources  Beijing 《岩矿测试》1995,14(2):114-161

研制了霓霞正长岩，粗面岩，花岗闪长岩，辉长石，流纹岩及白云岩６种不同类型的岩石标准物质，对用Ｘ射线荧光光谱均匀性检验实际取样量进行了探讨，选择分析测试方法时，除采用了标准方法和长期应用的分析方法外，还采用了近年发展起来的新技术新方法，在定值中应用了多参数统计定值模式，给出了６９个元素的标准值和参考值，该批标准物质于１９９１年１月经国家技术监督局审核批准为国家一级标准物质，编号分别为ＧＢＷ０７１０９  相似文献   

扬子北缘晋宁期望江山基性岩体的地球化学特征及其构造背景   总被引：11，自引：2，他引：11  

凌文黎  王歆华  程建萍 《矿物岩石地球化学通报》2001,20(4):218-221

钐 钕同位素定年和系统的元素 同位素地球化学研究表明 ,位于扬子克拉通北缘的望江山基性岩体形成于约 785± 88Ma的晋宁期 ,并具有陆内裂谷环境岩浆作用的地球化学属性 ,与时代为 0 95～ 0 .90Ga、具岛弧型火山岩特征的西乡群明显不同 ,标志该地区于新元古代经历了由洋壳消减的大陆边缘向陆内裂谷转变的构造演化。  相似文献   

Fischer Plots of Wumishan Cyclothems,Precambrian Records of Third-OrderSea-Level Changes     

Mei Mingxiang Faculty of Earth Sciences  Mineral Resources  China University of Geosciences  Beijing Ma Yongsheng China Petrochemical Corporation 《中国地质大学学报(英文版)》2001,12(1)

INTRODUCTIONThe Mesoproterozoic Wumishan Formation in Jixian,Tianjin is a succession of 3 300 m thick carbonate strata (Fig.1) where stromatolite biostromes and thrombolite bioherms arebest developed. The formation period of Wumishan Formation,about 100 Ma ((310120) Ma, (l 2071 10) Ma. Wang et al.,1995), is categorized as the Ectasian period of the Mesoproterozoic. Varieties of stromatolites in Wumishan Formation,such as Pseudogymnosolen mopanyuense, Scyphus parous,Conophoton conse…  相似文献   

The metamorphic complex of Beloretzk, SW Urals, Russia — a terrane with a polyphase Meso- to Neoproterozoic thermo-dynamic evolution     

U. A. Glasmacher  W. Bauer  U. Giese  P. Reynolds  B. Kober  V. Puchkov  L. Stroink  A. Alekseyev  A. P. Willner 《Precambrian Research》2001,110(1-4)

An integrated geological study of the tectono-metamorphic evolution of the metamorphic complex of Beloretzk (MCB) which is part of the eastern Bashkirian mega-anticlinorium (BMA), SW Urals, Russia shows that the main lithological units are Neoproterozoic (Riphean and Vendian age) siliciclastic to carbonate successions. Granitic, syenitic and mafic intrusions together with subaerial equivalents comprise the Neo- and Mesoproterozoic magmatic rocks. The metamorphic grade ranges from diagenetic and very low grade in the western BMA to high-grade in the MCB. The N–S trending Zuratkul fault marks the change in metamorphic grade and structural evolution between the central and eastern BMA. Structural data, Pb/Pb-single zircon ages, ⁴⁰Ar/³⁹Ar cooling ages and the provenance signature of Riphean and Vendian siliciclastic rocks in the western BMA give evidence of Mesoproterozoic (Grenvillian) rifting, deformation and eclogite-facies metamorphism in the MCB and a Neoproterozoic (Cadomian) orogenic event in the SW Urals. Three pre-Ordovician deformation phases can be identified in the MCB. The first SSE-vergent, isoclinal folding phase (D₁) is younger than the intrusion of mafic dykes (Pb/Pb-single zircon: 1350 Ma) and older than the eclogite-facies metamorphism. High P/low T eclogite-facies metamorphism is bracketed by D₁ and the intrusion of the Achmerovo granite (Pb/Pb-single zircon: ≤970 Ma). An extensional, sinistral, top-down-to-NW directed shearing (D₂) is correlated with the first exhumation of the MCB. E-vergent folding and thrusting (D₃) occurred at retrograde greenschist-facies metamorphic conditions. The tremolite ⁴⁰Ar/³⁹Ar cooling age (718±5 Ma) of amphibolitic eclogite and muscovite ⁴⁰Ar/³⁹Ar cooling ages (about 550 Ma) of mica schists indicate that a maximum temperature of 500±50 °C was not reached during the Neoproterozoic orogeny. The style and timing of the Neoproterozoic orogeny show similarities to the Cadomian-aged Timan Range NW of the Polar Urals. Geochronological and thermochronological data together with the abrupt change in structural style and metamorphism east of the Zuratkul fault, suggest that the MCB is exotic with respect to the SE-margin of the East European Platform. Thus, the MCB is named the ‘Beloretzk Terrane’. Recognition of the ‘Beloretzk Terrane’ and the Neoproterozoic orogeny at the eastern margin of Baltica has important implications for Neoproterozoic plate reconstruction and suggests that the eastern margin of Baltica might have lain close to the Avalonian–Cadomian belt.  相似文献   

攀枝花层状基性侵入体氧同位素初步研究          下载免费PDF全文

牟保磊 《岩石矿物学杂志》1991,(1)

攀枝花层状辉长岩侵入体,自下而上可分为四个岩带。各种样品的δ18O值: 8个全岩样品中的6个为 6.27— 6.91‰;23个钛磁铁矿中的19个为 1.28— 2.39‰;21个斜长石中的12个为 6.18— 7.60‰。氧同位素特征表明,岩体源自上地幔。Ⅰ岩带氧同位素平衡温度较低455℃—730℃,可能是成岩后叠加地质作用影响的结果;Ⅱ岩带856—1045℃;Ⅲ岩带652—740℃;Ⅳ岩带62 1.—871℃。  相似文献   

Taxonomy and affinity of Early Mesoproterozoic megascopic helically coiled and related fossils from the Rohtas Formation, the Vindhyan Supergroup, India     

Mukund Sharma  Yogmaya Shukla   《Precambrian Research》2009,173(1-4):105

A well preserved assemblage of compressed, straight, circular to sinuously coiled megascopic and helical carbonaceous fossils and other varied megascopic morphoforms are known from the Early Mesoproterozoic Rohtas Formation, Semri Group within Vindhyan Supergroup exposed in Katni district of central India. These megascopic remains are preserved as impressions, compressions, partially mineralized remains, and/or epi-relief. Some of the forms are typical filamentous empty sheaths and others are trichomes, with cell like entities under various stages of degradation. This study, based on fresh collections and also of the topotype material of the helically coiled megascopic fossils, straight forms and related fossilized remains occurring as epi-relief from Katni indicate that the two morphotaxa are distinct entities and possibly appear to be prokaryotes. Grypania spiralis and Katnia singhii are most likely of cyanobacterial origin. Spirally coiled and circular fossils, with epi-relief, and which probably represents a tissue grade organism, are considered as Spiroichnus beerii Mathur, 1983. Linear sheet-like carbonaceous solitary form has been placed in the morphotaxon Proterotainia and described as P. katniensis n. sp. Certain rare circular, carbonaceous forms are considered as Chuaria sp. A few circular disc-like forms found in the assemblage are treated as dubiofossils.  相似文献   

天津蓟县高于庄组微亮晶(MT)碳酸盐岩的沉积环境及成因探讨   总被引：2，自引：0，他引：2  

王德海  孟祥化  郭峰  任国选  葛铭 《吉林大学学报(地球科学版)》2009,39(6)

微亮晶(MT)碳酸盐岩是发育在中、新元古代的特殊碳酸盐岩,全球分布广泛,MT构造由纯净、等粒的微亮晶方解石组成.天津蓟县中元古界高于庄组发育丰富的MT碳酸盐岩,并且在浊积岩中发现新的MT类型.详测高于庄组剖面,通过米级旋回类型划分、沉积环境、费希尔图解、扫描电镜、电子探针研究,并结合海平面变化、Sr和C同位素研究表明:原生MT构造主要发育在碳酸盐岩台地潮下型,深水非对称型米级旋回中上部的泥晶灰岩、细粉屑灰岩、钙质泥岩以及浊积岩球体的核心部位;MT碳酸盐岩主要发育在米级旋回海平面上升的高水位时期,~(87)Sr/~(86)Sr 值较低(小于0.709 67),δ~(13)C值为(0±1)‰的古海水环境中.  相似文献   

Mantle Input to the Crust in Southern Gangdese, Tibet, during the Cenozoic: Zircon Hf Isotopic Evidence     

Mo Xuanxue  Dong Guochen  Zhao Zhidan  Zhu Dicheng  Zhou Su  Yaoling Niu 《中国地质大学学报(英文版)》2009,20(2)

The Quxu (曲水) complex is a typical Intrusive among the Gangdese batholiths. Two sets of samples collected from the Mianjiang (棉将) and Niedang (聂当) villages in Quxu County, Including gabbro, mafic micro-enclaves (MME), and granodiorites in each set, were well dated in a previous SHRIMP zircon U-Pb analysis (47-51 Ma). In this article, the same zircons of the 6 samples were ap-plied for LA ICP-MS Hf isotopic analysis. The total of 6 samples yields 176Hf/177Hf ratio ranging from 0.282 921 to 0.283 159, corresponding to εHf(t) values of 6.3-14.7. Their Hf depleted-mantle modal ages (TDM) are in the range of 137-555 Ma, and the zircon Hf isotope crustal model ages (TDMC) range from 178 to 718 Ma. The mantle-like high and positive εHf(t) values in these samples suggest a mantle-dominated input of the juvenile source regions from which the bathollth originated. The large varia-tions in εHf(t) values, up to 5-e unit among zircons within a single rock and up to 15-e unit among zir-cons from the 6 samples, further suggest the presence of a magma mixing event during the time of magma generation. We suggest that the crustal end-member involved in the magma mixing is likely from the ancient basement within the Lhasa terrane itself. The zircon Hf isotopic compositions further suggest that magma mixing and magma underplating at about 50 Ma may have played an important role in creating the crust of the southern Tibetan plateau.  相似文献   

滇中中元古界大龙口组地震灾变事件及地质意义   总被引：4，自引：1，他引：3  

武振杰  张传恒  姚建新 《地球学报》2009,30(3):375-386

软沉积物变形构造是确定古地震存在的关键证据之一。笔者在云南易门地区进行野外露头剖面调 查时, 在滇中新元古代大龙口组中识别出了3个地震事件层, 其中发现大量的水塑性褶皱、液化构造等变形构造, 主要类型包括微褶皱纹层、与液化脉有关的褶皱、与液化层有关的褶皱和受侧向挤压而成的顺层滑动、碟状泄水构造、液化脉、液化沙侵、水压破裂等构造。此外, 臼齿构造与水塑性褶皱、液化构造等地震成因变形构造伴生发育, 并且其脉体形态、大小、优势方位等与后者的分布、变形样式、强度等有一定的对应关系。软沉积物变形构造及臼齿构造的形态、位态及发育层位特征表明, 它们的驱动机制是地震活动。迄今为止, 已发现的滇中地区大龙口组震积岩均分布于罗茨?甘庄断裂的东侧, 指示软沉积物变形、臼齿构造与西缘控盆断裂间存在密切的成因联系。  相似文献   

燕山地区中元古界高于庄组和杨庄组地球化学特征及环境意义   总被引：7，自引：1，他引：6  

汪凯明  罗顺社 《矿物岩石地球化学通报》2009,28(4):356-364

在燕山地区中元古界高于庄组与杨庄组地层野外露头沉积特征研究的基础上,结合区域地质背景,根据26件碳酸盐岩样品的常量元素和微量元素相关关系、组分含量及某些元素的比值对特征,探讨了研究区元素的沉积地球化学特征与古环境意义。研究表明,（1）碳酸盐岩中Sr与CaO呈明显正相关;Al2O3、K2O与TiO2之间呈明显的正相关;SiO2与CaO、MgO呈负相关;Na2O与MgO呈弱正相关;MnO仅与FeO有弱正相关关系。（2）Sr主要赋存于方解石晶格中,Sr和1000×Sr/Ca值随沉积水体的加深而增大,可作为判断古水深的标志。（3）据Sr/Ba、镁铝比值（m=100×MgO/Al2O3）、MgO/CaO值及Ti等元素特征分析,高于庄组与杨庄组的沉积环境有较大差异,高于庄组为潮湿气候下陆源碎屑供应匮乏的远岸陆表海沉积,以高于庄组三段沉积时水体最深;而杨庄组为干热气候下的近岸陆表海沉积,有较多的陆源碎屑物质供应。总之,元素地球化学特征反映的沉积环境与宏观岩性特征所得出的结论是一致的,这表明地球化学特征与沉积环境关系密切,地球化学特征可作为沉积相分析的重要标志。  相似文献