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东昆仑南缘布青山构造混杂岩带哥日卓托闪长岩体年代学、地球化学特征及其地质意义 总被引：5，自引：0，他引：5
对东昆仑南缘布青山构造混杂岩带哥日卓托闪长岩体进行了锆石U-Pb年代学和岩石地球化学研究,以便对其形成时代和岩石成因进行约束.结果表明,哥日卓托闪长岩锆石Th/U比值(0.63～1.28)较高,阴极发光图像显示锆石内部发育振荡环带,具岩浆成因特点;LA-ICP-MS锆石U-Pb年龄为225.8±1.5Ma(MSWD=0.53),表明其形成时代为晚三叠世早期.岩体的SiO2含量在53.07％～58.74％之间,Al2O3(14.66％～16.17％)含量相对较高,全碱含量较低(4.76％～6.04％),高钾(1.60％～2.90％),里特曼指数σ在1.69～2.66之间,属高钾钙碱性系列.稀土元素总量(∑REE)为158.36×10-6～211.50×10-6,δEu为0.85～0.97,稀土元素配分曲线呈右倾型,具有弱的负铕异常.高场强元素(Nb、Ta、P等)和大离子亲石元素(Ba、Sr、Ti等)具有明显的负异常,而Rb、U、La、Hf、Nd等元素具有明显的正异常.哥日卓托闪长岩形成于高温环境(800℃±),具有后碰撞岩浆活动的特征,是东昆仑地块与巴颜喀拉地块碰撞后地壳部分熔融的产物. 相似文献
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萨尔托海蛇绿混杂岩是西准噶尔地区达拉布特蛇绿混杂岩带的重要组成部分,其形成时代和构造环境颇具争议。通过LA-ICP-MS锆石微区原位U-Pb同位素测年,获得其中辉长辉绿岩的 206Pb/238U 加权平均年龄为388.8±1.1 Ma,确定该蛇绿混杂岩形成于中泥盆世。岩石地球化学分析表明,纯橄岩(蛇纹岩)属于低Si、低碱、高Mg的变质橄榄岩,REE呈∑REE 偏低的平坦型分布模式,Cr、Ni和Co含量较高,变玄武岩属于高Ti、富Mg、富Fe、偏碱的拉斑系列,REE分布模式呈现 ∑REE 偏低、Eu异常不明显的平坦型曲线,微量元素分布模式为K、Cs、Th、Nb和P相对亏损的平坦型曲线,Zr/Nb比值低,总体表现出与E-MORB相似的特征。综合判断认为,萨尔托海蛇绿混杂岩形成于大陆裂谷向洋盆转化的构造环境,类似于"红海式"洋盆,为进一步深入认识新疆地区众多蛇绿混杂岩的形成构造环境提供了新思路。 相似文献
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Recognition of the hydrogeological potential using electrical sounding in the Khemisset-Tiflet region,Morocco 
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下载免费PDF全文 Fatima Zahra FAQIHI Anasse BENSLIMANE Abderrahim LAHRACH Mohamed CHIBOUT Mohamed EL MOKHTAR 《地下水科学与工程》2020,8(2):172-179
The low recharge of reservoirs and the increasing demand for water limit the potential of mobilized resources, especially in arid to semi-arid areas like Morocco. Integrated management is essential to safeguard this resource. In respect with this perspective, this work provides the analysis of hydrogeological potential of Khemisset-Tiflet region, which falls within the action area of the Sebou Hydraulic Basin Agency. The basis of our studies was as follows:(1) The interpretation of the existing geoelectric data;(2) application of geophysical methods for non-destructive reconnaissance and their integration into a Geographic Information System(GIS). The analysis demonstrates that: The map of the isohypses and the geoelectric cross-section of the substratum of the superficial roof aquifer show clearly a plunge associated with development of the Paleozoic roof in the South and the direction of flow of the surface water is from south to north, from the upper zone to the north of the El Kansera dam. These conclusions constitute very useful contribution for any resource management projects in this area. 相似文献
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共轭伸展褶劈理夹角的定量解析 总被引：16，自引：0，他引：16
９０ 年代初以来,中国地质学者先后在浙、皖、赣、湘的“板溪群”及震旦系中发现了古生代的生物化石。因此,再次将“板溪群”是否是前震旦纪的一个变质地层单位、江南古陆是否存在以及华南大地构造格局是否需要重新厘定等问题提了出来。１９９３ 年笔者于赣东北蛇绿混杂岩带内的“双桥山群”岩块中,首次发现了含晚古生代的放射虫硅质岩。１９９６ 年又在该混杂岩带多处的“双桥山群”岩块和“下震旦统志棠组”中找到了含晚古生代的放射虫硅质岩,还首次在“登山群拔竹坑组”中发现了早古生代的几丁虫化石。经数年野外多次观察和对室内化石鉴定、岩石地球化学测试结果以及岩石学特征的综合分析表明,所发现的含晚古生代放射虫硅质岩及其岩石组合是一套洋盆深水相沉积;登山群拔竹坑组,是早古生代的一套浅水陆棚 深水陆棚 半深海相沉积。结合同行学者在邻区“板溪群”研究方面取得的新成果,笔者认为：“板溪群”不是前震旦纪的一个变质地层单位,而是一个复杂的构造岩带,江南古陆是不存在的,华南从早古生代到中生代早期还经历了一次洋盆演化过程,现在的构造格局是印支运动奠定的 相似文献
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241Am is a useful tracer for understanding biogeochemical processes in the marine environment. 241Am also poses a potential radiation threat to human health due to the continuous increase of its concentration in the global
environment. We report a rapid analytical method for determining 241Am in marine sediments using isotope dilution sector-field inductively coupled plasma mass spectrometry (SF-ICP-MS) combined
with a high-efficiency sample introduction system (APEX-Q). A selective CaF2 co-precipitation procedure followed by TRU extraction chromatography was employed to effectively remove the major sediment
matrix and to pre-concentrate 241Am. We achieved an extremely low detection limit of 0.32 fg/g or 0.041 mBq/g (for 1 gram sediment), which is better than that
of alpha spectrometry, and it allowed the accurate determination of 241Am in low-level marine sediment samples. The accuracy and precision of the developed analytical method was evaluated using
a laboratory prepared Am isotope standard solution and Ocean Sediment reference material (IAEA-368). The results were satisfactory.
For sediment samples, overall chemical recoveries varied from 60–90%. The developed method was applied to the study of 241Am depth distribution in Sagami Bay, Japan, where we observed different depth profiles between 241Am activity and 239+240Pu activity. 相似文献
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Spheroidal carbonaceous fly-ash particles (SCPs) are produced by the high temperature combustion of fossil-fuels such as coal and oil. They are not produced by any natural processes and therefore are unambiguous indicators of atmospheric deposition from power generation and other industrial sources. In lake sediments, SCP concentration profiles are robust, replicable and often regionally characteristic such that the main profile features can be used for sediment dating. Previous work in the UK provided dates for the three main SCP profile features for Scotland, North Wales and Northern Ireland and also highlighted the lack of information for the rest of the UK. In this study, archived SCP data and new SCP concentration profiles were compiled from 80 radionuclide-dated sediment cores from across the whole of the UK in order to determine the regional coherence of temporal trends. Using SCP cumulative percentage profiles, with the SCP concentration peak set as 100%, dates for each 10% were produced for each core. Comparing these dates, eight distinct regions were found within the UK and dated cumulative profiles, with errors, were determined for each. Despite this regionality, the whole of the UK showed the same date for the start of the record (1850±25 years) and for the 40- and 50% (1940±15 and 1955±15, respectively). The national coherence of the former is thought to be due to the large confidence limits in the radionuclide dates for this period, whilst the latter is thought to be due to the impact from the major increase in electricity demand following the Second World War and the widespread introduction and use of cheap fuel-oil. Since the 1960s the trend has been one of increasing regionalisation resulting from the introduction of particle arrestor technology, the decline of heavy industry, the move to fewer and larger sources, particularly power stations, and an increase in accuracy for the dates of recent horizons. Regional trends are seen to compare well with industrial development in the UK and in some western areas influenced by emissions from Ireland. Areas of uncertainty remain in South Wales and the northern isles. A cumulative percentile was also calculated for each region for 1963 in order that this can be compared with the 241Am and 137Cs peaks. 相似文献
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PRELIMINARY STUDY ON THE OPHIOLITIC MELANGE IN THE YALU TSANGPU GRAND CANYON AREA 相似文献
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果芒错蛇绿混杂岩位于狮泉河—永珠—嘉黎蛇绿混杂岩带中段,是该带中保存较好的一套蛇绿混杂岩,其形成环境是确定狮泉河—永珠—嘉黎蛇绿混杂岩带构造属性的重要依据。对果芒错蛇绿混杂岩中的硅质岩进行了地球化学分析,为判断蛇绿混杂岩的形成环境提供新的约束条件。硅质岩通常呈几十厘米夹层产于玄武岩中,含有大量晚三叠世—白垩纪放射虫化石。硅质岩SiO2含量为71.38%～77.67%,Al2O3含量为8.62%～11.51%,MnO/TiO2值为0.28～0.35,（Ce/Ce＊）SN值为0.92～0.94,（La/Ce）SN值为1.13～1.17,反映了陆源物质的影响,而V、Ni、Cu和V/Y值高于大陆边缘硅质岩,与洋中脊和大洋盆地硅质岩相似,说明果芒错硅质岩可能形成于受陆源物质影响且与大陆边缘有一定距离的环境中。结合变质橄榄岩、镁铁质岩墙和玄武岩的地球化学特征,初步认为果芒错蛇绿混杂岩的形成环境为靠近大陆边缘的弧后盆地。 相似文献