泥盆纪海相碳酸盐岩碳同位素组成及演变   总被引：4，自引：0，他引：4       下载免费PDF全文

陈代钊  陈其英  江茂生 《沉积与特提斯地质》1995,(5):22-28

根据对六景泥盆系碳酸盐岩碳同位素组成的系统分析表明：从落霍柯夫期到布拉格期海洋中的δ~１３Ｃ是逐渐变重，埃姆斯期明显变轻．艾菲尔期又开始变重，特别是基维特期有较明显的正向偏移，并继续向上变重，至弗拉斯期与法门期之交达到最大，尔后逐渐变轻，反映了泥盆纪海洋碳同位素组成的演变趋势．这和泥盆纪（二级）海平面的变化趋势是基本一致的，反映海洋碳同位素组成与海平面变化及相关的气候和海洋、大气中ＣＯ_２含量的成因联系。弗拉斯阶－法门阶界线附近δ~１３Ｃ的变化型式表明其间发生的生物绝灭事件是海平面升降和缺氧环境的周期性扩展等因素的累积效应的结果．  相似文献   

云南老王寨金矿区煌斑岩中碳酸盐的化学成分及其意义   总被引：3，自引：0，他引：3  

黄智龙  王联魁 《矿物岩石》1995,15(4):30-33

本文报道了云南老王寨金矿区非矿化、矿化煌斑岩中不同产状碳酸盐的化学成分，结果表明本区煌斑岩中为次生碳酸盐，原生碳酸盐含量不超过１％；煌斑岩蚀变、矿化为不同阶段的产物；碳酸盐脉活动发生在成矿作用之后。  相似文献   

东海西湖凹陷早第三纪烃源岩生烃组分剖析   总被引：1，自引：0，他引：1  

李贤庆  钟宁宁  王铁冠  熊波  黄光辉  刘道燕  葛和平  林积桐 《煤田地质与勘探》1995,(6)

采用有机岩石学分析方法，结合有机地球化学资料，剖析了东海盆地西湖凹陷早第三纪烃源岩。该烃源岩富镜质组，贫惰性组，含一定数量的壳质组和腐泥组（１０％～３０％）。壳质组＋腐泥组含量与氯仿沥青、总烃和有效碳等参数密切正相关；树脂体和孢子体＋藻类体分别是早期生烃和晚期生烃的重要组分。在此基础上提出了西湖凹陷烃源岩的生烃模式。  相似文献   

Strain-related differences in the crystal growth of white mica and chlorite: a TEM and XRD study of the development of metapelitic microfabrics in the Southern Uplands thrust terrane, Scotland   总被引：2，自引：0，他引：2  

R. J. MERRIMAN  B. ROBERTS  D. R. PEACOR  S. R. HIRONS 《Journal of Metamorphic Geology》1995,13(5):559-576

Abstract TEM and XRD techniques were used to study crystal growth characteristics of the fabric-forming phyllosilicates which developed in response to low-grade metamorphism and tectonic imbrication in part of the Southern Uplands thrust terrane. Prograde regional metamorphism, ranging from late diagenesis through the anchizone to the epizone, was accompanied by the development of a slaty cleavage which is commonly bedding-parallel. TEM-measured mean thicknesses of white mica and chlorite crystallite populations increase with advancing grade and correlate with XRD-measured crystallinity indices. Analytical TEM data show that prograde changes in composition lead to a net loss of Si, Ca and minor Fe from the fabric-forming phyllosilicates. White micas are paragonite-poor phengites with a mean b lattice parameter of 9.037 Å, and indicate an intermediate pressure series of metamorphism with a field gradient of <25° C km^-1. Chlorite compositions evolved from diabantite (with intergrown corrensite) to ripidolite over an estimated temperature range of 150–320° C. Field gradient and temperature estimates suggest that crystal growth and fabric development occurred at burial depths ranging from 6 km to at least 13 km in the thrust terrane. During late diagenesis, crystal growth of white mica and chlorite was predominantly a consequence of polytypic and phase transitions, and resulted in similar size distributions which resemble typical Ostwald ripening curves. Under anchizonal and epizonal conditions, white mica grew more rapidly than chlorite because of its greater ability to store strain energy and recover from subgrain development; as a result crystal thickness distributions are not typical of Ostwald ripening. In contrast, chlorite crystals which grew under these conditions developed subgrain boundaries at high strain rates which were only partially recovered at low strain rates; these retained dislocations reduce the crystallite thicknesses detected by TEM and XRD, compared with those of white mica. These differences in strain-induced crystal growth indicate that white mica (illite) and chlorite crystallinity indices are likely to show significant differences where low-grade metamorphism is closely associated with tectonic fabric development.  相似文献   

内蒙白云鄂博矿区H₉中火山岩岩石特征及其意义   总被引：18，自引：1，他引：18  

袁忠信  白鸽  吴澄宇  丁孝石  张宗清 《矿床地质》1995,14(3):197-204

白云鄂博矿区Ｈ＿９地层岩石被中外学者长期看作是板岩或页岩，经近期研究发现岩性极为复杂。Ｈ＿９地层岩石是一套呈互层产出的粗面岩、流纹岩、流纹英安岩、变辉绿岩、白云岩、石英岩、黑云母岩、钠闪石－长石岩、钠辉石－长石岩、红柱石－黑云母角岩及碳质绢云板岩等。文中详细论述了这些火山岩石的结构构造、矿物成分和岩石化学成分，以及微量元素。对Ｈ＿９地层中火山岩，尤其是粗面质火山碎屑岩的确定，对了解白云鄂博矿床的成因和白云鄂博群形成的地质背景有重要意义。  相似文献   

塔里木河流域地表水资源及径流组成   总被引：11，自引：3，他引：11  

尤平达 《干旱区地理》1995,18(2):29-35

塔里木河流域内水系的分布几乎包括整个塔里盆地，水资源在全流域不仅是农业的命脉，也是制约国民经济发展的重要因素，同时也是制约和影响生态环境最敏感的因子。本文根据塔里木河流域干，支流水文测站长期的实际观测资料，加以深入研究分析，对该流域各源流及干流的地表水资源量，径流组成以及年内分配情况，提出了较为翔实，可靠的数据，谨供流域水资源规划设计，管理调度等参考。  相似文献   

A ‘mathematical’ spider living on gravel plains of the Namib Desert     

G. Costa  A. Petralia  E. Conti  C. Hnel 《Journal of Arid Environments》1995,29(4)

In certain areas of the Namib gravel plains a new Ariadna sp. was discovered. It rims its vertical burrow with a stone circle, made on average of seven quartz stones. Some mathematical relationships between hole diameter, stone sizes and weight, and animal size were studied. A correlation was found, and stone selection by this spider postulated. Different hypotheses on the adaptive value of stone circle are suggested.  相似文献   

盐卤硼酸盐化学Ⅹ　Ⅹ　Ⅴ　Ⅱ盐湖卤水酸化过程中硼酸生长速率          下载免费PDF全文

李武  杨存道  高世扬  夏树屏  赵云惠 《盐湖研究》1995,(3)

本文提出了一种用激光散射跟踪溶液中粒子粒度在不同时间的分布，求取粒子生长速率的简便而可行的方法，得到了大柴旦盐湖卤水在硫酸酸化过程中硼酸晶体的生长速率，并提出解决酸法提础工艺中所得硼酸晶体粒度太小的方法。  相似文献   

Changes in the ionic composition of a saline lake,Mar Chiquita,Province of Córdoba,Argentina     

D. E. Martinez 《International Journal of Salt Lake Research》1995,4(1):25-44

Mar Chiquita is the largest water-body in Argentina according to area. This ranges from 2,000 km² in dry periods to 5,000 km² in humid ones. Its very high salinity ranged this century from 200 to 300 g/L, but an increase in the average rainfall in the basin since 1973 has led to a rise in lake level and the dilution of its waters to 78 g/L in 1978 and about 30 g/L in the late 1980s. Ionic strength decreased from 6.61 in 1970 to 0.541 in 1986. The composition of the water also changed, with increases in the proportions of sulphate, calcium and magnesium concentrations. The most important processes taking place in solution are calcite and gypsum equilibrium, formation of clay minerals, and sulphate reduction in the interstitial waters of the bottom sediments. The thermodynamic state of the solutions for different years has been obtained. Results show that the solution shifted from gypsum oversaturation in 1970 to gypsum equilibrium in 1978, and to gypsum undersaturation since 1982. A geochemical simulation of the composition of the solution from its origin from mean tributary composition, following a modified Hardie-Eugster model, has been developed using PHRQPITZ. The results agree with empirical observations.  相似文献   

Influence of fluid chemistry on shear-wave attenuation and velocity in sedimentary rocks   总被引：2，自引：0，他引：2  

Dung Vo-Thanh 《Geophysical Journal International》1995,121(3):737-749

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