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样品产于南海北部湾滨岸浅滩胶结较松散的长石石英砂岩中,属于上第三系下洋组。本文从海绿石形态、矿物的物理化学测试结果以及形成介质条件等方面,探讨该区海绿石特征和形成环境。 相似文献
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海绿石矿物一般是在正常盐度的浅海环境中生成,可作为良好的指相矿物。在无化石的地层中海绿石可用来测定同位素年龄、进行地层对比和解释地层间断。此外,海绿石也可作为储油层沉积环境的综合指标之一。 本文通过各种方法对我国某些地区砂岩类型的自生海绿石的矿物学特征作了综合系统的研究。试图通过从已知到未知、从现代到古代作对比,对松辽盆地的某些储油层段相环境的确定,提出必要的实际资料,进而来讨论它们的沉积环境。 相似文献
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关于东海现代沉积物中的海绿石,前人曾有过报道,但都限于一般性的描述。近年来我们对东海表层沉积物中的海绿石进行了较为系统的研究,工作范围为东经121°-129°,北纬26°30′-32°00′,样品233个。分别进行了镜下鉴定、透射电镜和扫描电镜观察,并以多晶X-射线衍射法,化学全分析、差热分析、红外吸收光谱和电子探针等方法进行较系统的矿物学研究。本文就东海表层沉积物中海绿石的矿物学特征,产状及分布进行阐述,并对其成因作了初步的探讨。 相似文献
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梁山位于陕西省汉中市附近,属西南地台的北部边缘。1979年,我系陈润业教授带领学生在梁山大南沟实习,于下寒武统郭家坝组底部,厚度不到1米的含海绿石土黄色灰质砂岩及灰白色砂质灰岩中,首次发现了小壳动物化石(图1),并提出了梁山地区有相当于梅树村期沉积的可能性。 相似文献
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作者研究了南海北部表层沉积物中10个站位的海绿石。用显微镜、各种谱仪、透射电镜、扫描电镜、电子探针和化学分析等方法,对海绿石的外表特征及矿物学特性,进行了较为系统的分析;并结合海绿石的产状和分布,研究了它们的成因及沉积环境问题。本区海绿石可分为生物状海绿石、页状海绿石和颗粒状海绿石;根据X射线和红外光谱等特征,有混合层海绿石和混合物海绿石两类;根据化学成份计算黑色生物状海绿石的晶体化学 相似文献
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天津蓟县中元古界铁岭组叠层石灰岩中原地海绿石的沉积学意义 总被引:5,自引:1,他引:4
天津蓟县剖面中元古界铁岭组二段叠层石灰岩中普遍发育海绿石。野外观察表明,海绿石主要分布在叠层石柱体间的泥晶灰岩中,呈薄膜状富集在叠层石鞘外缘;微观特征分析表明,海绿石呈不规则状的胶体形式,显示了原地海绿石的基本特点。电子探针的组分分析表明,铁岭组中的海绿石为中成熟度的海绿石。由于产在潮下高能柱状叠层石灰岩中,铁岭组中的海绿石并不反映低沉积速率或沉积间断的沉积条件,与现代海绿石的形成环境具有明显的差异。因此,中元古界铁岭组叠层石灰岩中的中成熟度原地海绿石是特殊沉积背景下的独特产物,为研究海绿石在地质历史时期产出的多样性提供了一个重要实例。 相似文献
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徐州大北望寒武系徐庄组发育不同类型海绿石,为探讨不同类型海绿石的成因,基于海绿石的矿物学、地球化学及沉积环境分析,利用偏光显微镜、X 射线衍射及电子探针等方法对各含海绿石岩层及不同类型海绿石进行系统对比研究查明海绿石的指相意义。结果表明,徐庄组发育颗粒状、碎屑假象状和胶团状三种类型海绿石,其中颗粒状海绿石具有中—高含量钾、高含量铁、砂岩中—高含量铝、石灰岩中低含量铝等特征;碎屑假象状海绿石具有变化大的钾、铁、铝,且保持着其母质形态特征;胶团状海绿石具有高钾、高铁、低铝特点。颗粒状海绿石成因符合颗粒绿化理论,砂岩中海绿石易受环境影响;碎屑假象状海绿石成因符合层状晶格理论及假象替代理论,受到交代和溶蚀作用,因受较强的水动力条件影响成分变化较大;胶团状海绿石是凝胶状海绿石通过胶结作用沉淀,形成于稳定环境中。 相似文献
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在内蒙古西乌珠穆沁旗晚石炭世—早二叠世阿木山组第三段泥晶灰岩中发现有海绿石。对海绿石的微观特征分析表明,阿木山组海绿石呈团粒状结构,同时呈胶体产出于方解石周边,显示了原生海绿石的基本特点。电子探针的组分分析表明,阿木山组中的海绿石为高成熟度的海绿石。通过对不同地区和不同环境下海绿石的组分特征分析,建立了一种海绿石沉积的理想模式,同时揭示了阿木山组第三段海绿石化作用是在含氧量不够充分的弱还原状态下的正常浅海中进行的。本区阿木山组的下碎屑岩段和上灰岩段是在海水两进两退环境下的沉积,阿木山组灰岩中发现的海绿石则有可能代表了一个海进的开始。本区海绿石的发现及研究,对于进一步研究该区层序地层特征、地层格架及区域地层对比具有重要意义。 相似文献
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1974年在一水晶矿石英脉晶洞中,发现了一种含Ba、Li的硅酸盐新矿物--纤钡锂石。我们对纤钡锂石进行了光性研究、比重测定、差热及热失重分析、红外光谱分析、X射线单晶结构分析等工作,现分述如下。 相似文献
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副硫锑钴矿是硫锑钴矿(CoSbS)的一个同质多象变体。1970年由卡布里(L. J. Cabri)等人发现于加拿大安大略州,他们对该矿物进行了化学分析及X射线粉晶分析等研究。测得该矿物属斜方晶系,a=5.764,b=5.952,c=11.635,空间群为Pbca,Z=8。 相似文献
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V. A. Drits T. A. Ivanovskaya B. A. Sakharov B. B. Zvyagina A. Derkowski N. V. Gor’kova E. V. Pokrovskaya A. T. Savichev T. S. Zaitseva 《Lithology and Mineral Resources》2010,45(6):555-576
The detailed mineralogical and structural-crystal-chemical characteristics are reported for the first time for glauconite grains extracted from the fine-platy silty-sandy dolomites at the roof of the lower subformation of the Yusmastakh Formation (Riphean, Anabar Uplift, North Siberia). Based on the complex study (X-ray diffraction, classical chemical analysis, microprobe analysis, IR-spectroscopy, thermogravimetric analysis, scanning electron microscopy with microprobe analysis, and Mössbauer spectroscopy), it was demonstrated that the studied glauconite sample is characterized by unique chemical and structural heterogeneity.The mineral structure consists of micaceous (90%), smectite (6%), and di-trioctahedral chlorite (4%) layers. Mica is classed with Al-glauconite (Al > Fe3+) with elevated Mg content. The elevated Mg mole fraction of the mineral is caused by the presence of Mg-bearing brucite-type interlayers of di-trioctahedral chlorite and the high Mg content in the octahedral sheets of 2: 1 layers. It was first discovered that glauconites are characterized by the heterogeneous distribution of cations over the available trans- and cis-octahedra due to the coexistence of trans- and cis-vacant octahedra and small trioctahedral clusters in octahedral sheets. The distribution of isomorphic cations over the accessible octahedral sites is also heterogeneous due to the tendency of Fe, Mg and Al, Mg cations to segregation and formation of corresponding domains.It was found that structure of the studied glauconite has a specific stacking defect: in addition to the predominant subsequent layers of similar azimuthal orientation according to 1M type (~77%), some layer fragments are rotated at 180° (~15%) and ±120° (8%). The structural-crystal-chemical heterogeneity of the mineral is explained by the fact that its microcrystals grew in the dolomitic sediment under nonequilibrium conditions of the reduction zone of a shallow-water basin with a sufficiently high content of Mg cations, which significantly contributed to the glauconite formation. 相似文献
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K-Ar and Rb-Sr ages from glauconites are about ten to twenty per cent lower than the age of sedimentation. Previous studies have indicated that these low ages are not attributable to normal diffusion loss of Ar from glauconite crystallites.The possibility of argon loss from ‘open’ potassium sites, such as on crystal surfaces and from expanded layers, was investigated by acid dissolution techniques. These studies show that potassium is removed from glauconites with low expandabilities at three different rates. The highest dissolution rate corresponds to cation exchange and comprises five to ten per cent of the total potassium. About five per cent of the total potassium is removed at a much slower rate than that of cation exchange, but at an order of magnitude faster than the bulk of the potassium.Activation energies calculated from rate constants determined at 50° and 80°C, for one sample gave values of 19 kcal/mole for the lowest dissolution rate and 14 kcal/mole for the intermediate rate.It appears that low radiometric ages from glauconites can be largely explained by the presence of potassium in sites where argon is readily lost, although such factors as late epigenetic gain of potassium by glauconite may also contribute to their low radiometric ages. A method is described for making quantitative corrections for such daughter product loss in radiometric age determinations. 相似文献