新疆东昆仑野牛泉石英闪长岩与英安斑岩的^40Ar／^39Ar同位素年龄   总被引：1，自引：2，他引：1  

郝杰  刘小汉  桑海清 《地质通报》2003,22(3):165-169

对出露在新疆东昆仑落雁山—阿尔喀山一带闪长岩-花岗闪长岩带中的野牛泉石英闪长岩中的角闪石和次火山岩英安斑岩中的黑云母2种单矿物进行40Ar39/Ar同位素定年,分别获得角闪石(219±1.4)Ma坪年龄和(220±11)Ma等时年龄,黑云母(218.59±0.94)Ma坪年龄和(226±11)Ma等时年龄,证实它们形成于晚三叠世。由于它们具有弧侵入体的岩石学和地球化学特征,因此该年龄的确定对于以木孜塔格-鲸鱼湖蛇绿混杂带为标志的南昆仑造山带构造演化研究具有重要意义。  相似文献   

福建加良山寿山石的矿物学特征及成因   总被引：2，自引：0，他引：2       下载免费PDF全文

孙旎  崔文元徐湘 《岩石矿物学杂志》2003,22(3):273-278

应用电子探针、化学分析、X射线衍射、红外光谱、拉曼光谱等分析手段对加良山寿山石进行了研究，结果表明其主要组成矿物是叶蜡石，并含有硬水铝石和石英，大部分叶蜡石以2M型为主。该矿区为火山热液矿床，成矿明显分为早、中、晚3个阶段，成矿温度285～405℃，压力小于0．26GPa。  相似文献   

Compartmentalisation of fluid migration pathways in the sub-Andean Zone, Bolivia     

Isabelle Moretti  Pierre Labaume  Simon M. F. Sheppard  Jacques Boulgue 《Tectonophysics》2002,348(1-3)

Numerous observations indicate that faults play a major role on the migration pathways of fluids in the Bolivian sub-Andean Zone. Most oil seeps in the foothills are located on faults, but oil fields in the foredeep are closed by faults. In the foothills, analysis of cements in fractures inside and around fault zones indicates that the faults act as barriers for transversal migration but can be preferential lateral migration pathways for both hydrocarbons and water. A detailed study of these apparent contradictions suggests that the hydraulic behaviour of faults changes with depth in relation with sandstone diagenesis, but it is strain-independent. From microstructural analyses of fault zones, we suggest that the main controlling factor is temperature, which facilitates or inhibits quartz precipitation. This result implies that the same fault is a barrier for lateral and transversal migration at depths >3 km, due to sealing of fractures by authigenic quartz at T>80 °C, and is a lateral drain in its shallower parts. As a result, the various thrust sheets are isolated from a hydraulic point of view, whereas migration in the foreland may take place over long distances (>100 km).  相似文献   

Rb—Sr Isotopic Chronology of the Au—Bearing Quartz Veins in Gold Depostits in the Eastern Part of North China Platform     

魏俊浩  刘丛强  唐红峰 《中国地球化学学报》2002,21(4):374-382

In the eastern part of Chian there had occurred large-scale gold mineralization during the Mesozoic,resulting in a large number of inprotant gold ore-concentrated areas.In this paper we have selected some isotope data(including four gold deposits previously studied and two gold deposis in this work)of Au-bearing quartz veins of the representative gold deposits in six impor-tant gold ore-concentrated areas in the periphery of the North China Platform and calculated their metallogenic ages using the method of Ludwig(2.90 version).The results show that the repre-sentative gold deposits in the six gold ore-concentrated areas were formed during the Mesozoic.  相似文献   

A Holocene record of allochthonous, aeolian mineral grains in an Australian alpine lake; implications for the history of climate change in southeastern Australia   总被引：2，自引：0，他引：2  

Shawn Stanley  Patrick De Deckker 《Journal of Paleolimnology》2002,27(2):207-219

A radiocarbon-dated core, NC, taken in the alpine Blue Lake in the Snowy Mountains of southeastern Australia provides a Holocene record of sedimentation that consists mainly of organic clays. Two types of quartz grains are recovered from 81 samples from the core. One type consists of angular grains, with frequently shattered faces, which originates from granitic lithologies present within the small catchment area of the lake. The other type is characteristically rounded to subrounded, often textured with frequent silica coating and is considered to have been deposited within the lake and its catchment by aeolian processes. These aeolian grains are thought to have been transported along the main dust path that ferries aeolian dust from the Mallee region, west of the Snowy Mountains, as far as the southeastern Tasman Sea. Aeolian grains with the largest size occur over approximately the last 1.6 ka of the Holocene and this indicates an increase of climatic instability, with arid phases that commenced about 3.5 ka. At 2 ka, a wet period in southeastern Australia coincided with low aeolian input at Blue Lake. The period of consistent reduced aeolian activity spans the 7.6 to 5.5 ka interval at Blue Lake.  相似文献   

X射线管辐射谱线分析   总被引：1，自引：0，他引：1  

宓锦校  沈今川 《矿物学报》1997,17(2):164-168

经Ni滤波片过滤的CuKa射线，并非为真正的单色X射线，其中含部分白色X射线和非CuKa特征谱线。用石英分析晶体（101）衍射面网将混入CuKa射线中的各种波长的谱线分离开，并测定其波长的范围，确定在CuKa射线中含有铁、镍、钴、铬四种元素的K系列谱线和钨的L系列谱线。发现在X射线粉末图谱中用CuKa（或Kβ）无法解释的弱衍射线却是由铁、镍等元素的特征谱线混入引起的。  相似文献   

石英位错的会聚束电子衍射研究     

赵文霞  刘祥文 《矿物岩石》1997,17(3):1-4

矿物中位错的柏格斯矢量ｂ反映了矿物发生变形时所经历的条件，对它的精确测定为构造地质学研究提供了定量依据。本文用会聚束电子衍射的方法对石英位错进行了测定，同传统的双束法相比较，此方法更为简单和方便。  相似文献   

冀西北东坪金矿床的成矿期次及成矿阶段研究   总被引：1，自引：0，他引：1  

莫测辉  王秀璋  程景平  梁华英 《矿物岩石地球化学通报》1997,(3)

冀西北东坪金矿床的成矿期次及成矿阶段研究莫测辉（华南农业大学资源环境学院，广州５１０６４２）王秀璋程景平梁华英（中国科学院广州地球化学研究所，广州５１０６４０）关键词金矿床石英脉型蚀变岩型成矿期次成矿阶段“石英脉型”与“蚀变岩型”是中温（中深）热液脉...  相似文献   

南极普里兹湾柱样中石英颗粒的表面结构   总被引：6，自引：0，他引：6       下载免费PDF全文

王祥珍  吴时国  李传荣  陈虹勋  罗又郎 《极地研究》1997,9(2):12-25

本文统计分析了南极普里兹湾陆坡区一个柱样（ＮＰ９５１）１３个层位的石英颗粒的形态和表面结构。石英表面呈现出强烈的冰川运动和较弱的化学溶蚀－沉淀作用留下的表面特征，表明该沉积物主要是处于低能海洋环境中的冰碛物。石英颗粒因化学溶蚀－沉淀作用形成的组合表面特征的定量统计结果与矿物的Ｘ射线衍射和微体古生物的分析结果相对应，能较好地解释该海区经历的沉积环境和古气候变化。  相似文献   

The relation between grain size and Ar/Ar date for Alpine white mica from the Siviez-Mischabel Nappe, Switzerland     

Michelle J. Markley  Christian Teyssier  Mike Cosca 《Journal of Structural Geology》2002,24(12):21

Variations in Alpine white mica ⁴⁰Ar/³⁹Ar dates from the cover units of the Siviez-Mischabel Nappe relate to regional variations in the thermal history of the nappe. We focus on three regions within the nappe: the central Siviez-Mischabel (CSM), the southern Siviez-Mischabel (SSM), and the eastern Siviez-Mischabel (ESM). Our approach weaves together observations of quartz and mica textures in thin section, the variation of ⁴⁰Ar/³⁹Ar date with grain size, considerations of the effective diffusion dimension (EDD) of argon in white mica, and a comparison of dates with diffusion model results. In the CSM, pressure solution of quartz and dislocation glide in mica accommodated Alpine deformation. Dates record mica growth during nappe emplacement from 40 to 36 Ma and do not vary with grain size. In the SSM and ESM, both mica and quartz show textures associated with dynamic recrystallization, and dates decrease with grain size. In the SSM, dates also agree with the timing of nappe emplacement, but in the ESM, dates significantly post-date the timing of nappe emplacement. A comparison of dates with diffusion model results supports inferences from rock fabrics that the SSM experienced higher peak temperatures than the CSM, even though dates from both units approximate the timing of mica growth. Dates obtained from the ESM, however, do not compare well with simple models, and the thermal evolution of this region of the nappe, in the neighborhood of the Simplon Fault Zone, is not well understood.  相似文献