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南水北调中线工程上第三系膨胀性硬粘土的工程地质特性研究 总被引:7,自引:5,他引:7
上第三系硬粘土在中国东部新生代沉积盆地具有广泛的分布 ,因其性质复杂而成为中国区域性特殊岩土研究的重要对象。纵贯于南阳盆地和华北盆地西缘的南水北调中线工程长距离地开挖在不同的上第三系硬粘土中。本文在对南阳盆地、方城宝丰、邯郸永年三渠段上百个原状样的物质组成、物理性质、物化性质、膨胀性和收缩性、强度特性系统测试分析的基础上 ,总结了各类硬粘土的工程地质特性及其形成机理和变化规律 ,并根据不同湿度、围压状态下的试验结果分析了硬粘土的工程环境效应 ,这对于认识上第三系硬粘土在开挖运营条件下的变形破坏机理有着重要的理论和实际意义。 相似文献
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准噶尔盆地西北缘侏罗系陆相碎屑岩储层的岩性差异较大,岩性对物性的控制作用明显。储层的孔隙类型多样,不同类型的孔隙在发育规模、丰度及有效性方面都存在显差异,次生溶蚀孔隙、原生粒间孔隙和残余粒间孔隙是最重要的有效孔隙类型。储层渗透率与孔隙度之间存在较好的半对数相关关系。通过设置一定的孔隙度和渗透率参数界线,对储层储集性能进行评价,将侏罗系储层的孔渗性能划分为5个级别,可与当前流行的砂岩储层孔渗性能分级相对应。通过对大量压汞参数样本的聚类分析,将储层的孔隙结构划分为4个类型。通过各类参数统计及曲线形态对比,对孔隙结构类型进行了定量结合定性的优劣评价。最后,结合孔渗性能级别、储集空间类型、孔隙结构类型、岩性等特征,对准噶尔盆地西北缘侏罗系储层进行了综合分类评价。 相似文献
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S. Bodorkos M. Sandiford N. H. S. Oliver P. A. Cawood 《Journal of Metamorphic Geology》2002,20(2):217-237
High‐T, low‐P metamorphic rocks of the Palaeoproterozoic central Halls Creek Orogen in northern Australia are characterised by low radiogenic heat production, high upper crustal thermal gradients (locally exceeding 40 °C km?1) sustained for over 30 Myr, and a large number of layered mafic‐ultramafic intrusions with mantle‐related geochemical signatures. In order to account for this combination of geological and thermal characteristics, we model the middle crustal response to a transient mantle‐related heat pulse resulting from a temporary reduction in the thickness of the mantle lithosphere. This mechanism has the potential to raise mid‐crustal temperatures by 150–400 °C within 10–20 Myr following initiation of the mantle temperature anomaly, via conductive dissipation through the crust. The magnitude and timing of maximum temperatures attained depend strongly on the proximity, duration and lateral extent of the thermal anomaly in the mantle lithosphere, and decrease sharply in response to anomalies that are seated deeper than 50–60 km, maintained for <5 Myr in duration and/or have half‐widths <100 km. Maximum temperatures are also intimately linked to the thermal properties of the model crust, primarily due to their influence on the steady‐state (background) thermal gradient. The amplitudes of temperature increases in the crust are principally a function of depth, and are broadly independent of crustal thermal parameters. Mid‐crustal felsic and mafic plutonism is a predictable consequence of perturbed thermal regimes in the mantle and the lowermost crust, and the advection of voluminous magmas has the potential to raise temperatures in the middle crust very quickly. Although pluton‐related thermal signatures significantly dissipate within <10 Myr (even for very large, high‐temperature intrusive bodies), the interaction of pluton‐ and mantle‐related thermal effects has the potential to maintain host rock temperatures in excess of 400–450 °C for up to 30 Myr in some parts of the mid‐crust. The numerical models presented here support the notion that transient mantle‐related heat sources have the capacity to contribute significantly to the thermal budget of metamorphism in high‐T, low‐P metamorphic belts, especially in those characterised by low surface heat flow, very high peak metamorphic geothermal gradients and abundant mafic intrusions. 相似文献
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Thermal waters hosted by Menderes metamorphic rocks emerge along fault lineaments in the Simav geothermal area. Thermal springs and drilled wells are located in the Eynal, Çitgöl and Na
a locations, which are part of the Simav geothermal field. Studies were carried out to obtain the main chemical and physical characteristics of thermal waters. These waters are used for heating of residences and greenhouses and for balneological purposes. Bottom temperatures of the drilled wells reach 163°C with total dissolved solids around 2225 mg/kg. Surface temperatures of thermal springs vary between 51°C and 90°C. All the thermal waters belong to Na–HCO3–SO4 facies. The cold groundwaters are Ca–Mg–HCO3 type. Dissolution of host rock and ion-exchange reactions in the reservoir of the geothermal system shift the Ca–Mg–HCO3 type cold groundwaters to the Na–HCO3–SO4 type thermal waters. Thermal waters are oversaturated at discharge temperatures for aragonite, calcite, quartz, chalcedony, magnesite and dolomite minerals giving rise to a carbonate-rich scale. Gypsum and anhydrite minerals are undersaturated with all of the thermal waters. Boiling during ascent of the thermal fluids produces steam and liquid waters resulting in an increase of the concentrations of the constituents in discharge waters. Steam fraction, y, of the thermal waters of which temperatures are above 100°C is between 0.075 and 0.119. Reservoir pH is much lower than pH measured in the liquid phase separated at atmospheric conditions, since the latter experienced heavy loss of acid gases, mainly CO2. Assessment of the various empirical chemical geothermometers and geochemical modelling suggest that reservoir temperatures vary between 175°C and 200°C. 相似文献
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Zheng Xilai Halldor Armannsson Li Yongle Qiu Hanxue 《Journal of Volcanology and Geothermal Research》2002,113(1-2)
In this study, representative samples from thermal wells and springs were chemically analyzed and geothermometers were used to calculate the deep temperatures of geothermal reservoirs on the basis of water–mineral equilibrium. In some cases, however, the chemical components are not in equilibrium with the minerals in the reservoir. Therefore, log(Q/K) diagrams are used to study the chemical equilibrium for the minerals that are likely to participate. The Na–K–Mg triangular diagram is also applied to evaluate the equilibrium of water with reservoir rocks. Standard curves at the reference temperatures are prepared to reveal which type of silica geothermometer is appropriate for the specified condition. This study shows that water samples from geothermal wells W9 and W12 are in equilibrium with the selective minerals, and chalcedony may control the fluid–silica equilibrium. It is estimated that there is an exploitable low-temperature reservoir with possible temperatures of 80–90°C in the Guanzhong basin. 相似文献
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断裂构造的遥感研究方法综述 总被引:1,自引:0,他引:1
断裂构造是一种基本的构造型式。断裂构造遥感研究是高新探测技术与地球科学的有机结合 ,是断裂构造常规研究方法的有益补充和向纵深拓展的必然趋势。该文从总体思路、具体内容、操作方法等各个不同角度系统地论述了断裂构造遥感研究的现状和发展趋势 ,并在断裂构造信息提取、光谱特征分析、空间结构分析 (包括分形分析 )等方面提出了一些观点。 相似文献