Subsurface structure of the volcanic centre of the České Středohoří Mountains, North Bohemia, determined by geophysical surveys     

J. Mrlina  V. Cajz 《Studia Geophysica et Geodaetica》2006,50(1):75-88

Former geophysical surveys performed in the region of the volcanic centre of the České Stř edohoří Mts. in North Bohemia (the Ohře Rift zone) showed that anomalous volcanic bodies and features can be effectively identified within sedimentary environment. For this reason we carried out new geophysical measurements in the area of the main mafic intrusion of essexitic character. The target was the exact location and geometry of the intrusion and its relation to other components of the volcanic centre. We used gravity, magnetic, shallow seismic and electromagnetic techniques. The new gravity and magnetic data were tied to the old databases so that we could investigate the area as a whole complex. Electromagnetic measurements were applied in the area of the expected extent of the intrusion, and the seismic measurements in the central part of the intrusion. Based on all the data, mainly on gravity modelling, we delineated not only the surface and subsurface extent of the intrusion, but we also defined the hidden relief of the intrusion. It was found that the intrusion is formed by a single body that has a few protrusions, and not by a set of separate individual intrusions, as indicated by surface outcrops. However, the body of the intrusion is affected by a major fault that caused lithological differences on both sides (essexite/monzodiorite). In detail we show the depth of the debris cover and the thickness of the weathered zone in the central part of the essexite body. We also derived indications of tectonic elements in the area of the intrusion in the main structural/tectonic direction in the region. The results will be utilized to establish a 3D geological model of the whole volcanic centre. This investigation may serve as an example of non-seismic geophysical exploration applied to the study of volcanic centres surrounded by sedimentary rocks.  相似文献   

The geology of Mount Hasan stratovolcano, central Anatolia, Turkey     

Erkan Aydar  Alain Gourgaud 《Journal of Volcanology and Geothermal Research》1998,85(1-4)

Mount Hasan is a double-peaked stratovolcano, located in Central Anatolia, Turkey. The magmas erupted from this multi-caldera complex range from basalt to rhyolite, but are dominated by andesite and dacite. Two terminal cones (Big Mt. Hasan and Small Mt. Hasan) culminate at 3253 m and 3069 m respectively. There are four evolutionary stages in the history of the volcanic complex (stage 1: Kecikalesi volcano, 13 Ma, stage 2: Palaeovolcano, 7 Ma, stage 3: Mesovolcano and stage 4: Neovolcano). The eruptive products consist of lava flows, lava domes, and pyroclastic rocks. The later include ignimbrites, phreatomagmatic intrusive breccias and nuées ardentes, sometimes reworked as lahars. The total volume is estimated to be 354 km³, the area extent 760 km². Textural and mineralogical data suggest that both magma mixing and fractional crystallization were involved in the generation of the andesites and dacites. The magmas erupted from the central volcanoes show a transition with time from tholeite to calc-alkaline. Three generations of basaltic strombolian cones and lava flows were emplaced contemporaneously with the central volcanoes. The corresponding lavas are alkaline with a sodic tendency.  相似文献   

Geochemistry and regional distribution of ophiolites and associated volcanics in Mianlüe suture, Qinling-Dabie Mountains     

Lai Shaocong  ZHANG Guowei  Dong Yunpeng  PEI Xianzhi  CHEN Liang 《中国科学D辑(英文版)》2004,47(4)

Systematic studies of the ophiolites and associated volcanics stretching more than 1500 km from the Derni-Nanping-Pipasi-Kangxian area in the west to the Qingshuihe area of the south Dabie Mountains in the east indicate the existence of a suture zone (the Mianl(u)e suture)and a vanished paleo-ocean basin (the Mianlue paleo-ocean basin) in the region. From west to east, ophiolitic melange associations distribute discontinuously along the suture. Rock assemblages include ophiolite, island arc and oceanic island rock series. The Mianlue paleo-ocean basin experienced its major formation and expending episode during the Carboniferous-Permian period. The finding of the suture zone and the paleo-ocean basin is tectonically significant in timing the collision between the North China-Qinling and Yangtze blocks and determining the formation and evolution of the Qinling orogenic belt.  相似文献   

Le jeu fini-Crétacé du front nord-pyrénéen aux environs de Cucugnan (Corbières méridionales,Aude, France)     

André Charrière  Michel Durand-Delga 《Comptes Rendus Geoscience》2004,336(13):1199-1208

The North-Pyrenean Front overthrust in northern direction was particularly active during the Upper Cretaceous, before the Upper Eocene tectonic renewal. Indeed, in the Eastern Pyrenees (Aude), ‘Garumnian’ (continental Upper Cretaceous–Palaeocene) formations lie transgressively upon the North-Pyrenean Triassic (Keuper) formation and upon the Albian beds of the Sub-Pyrenean Cucugnan slice. Relations between the North-Pyrenean Frontal Thrust and, to the northeast, the Corbières Nappe are discussed. <em>To cite this article: A. Charrière, M. Durand-Delga, C. R. Geoscience 336 (2004).em>  相似文献   

浅谈煤炭地勘单位的股份制改造     

朱文彬 《中国煤田地质》2003,15(2):63-64

探讨了煤炭地质单位股份制改造等方面的问题，提出了股份公司的组建应灵活多样、不拘于现成模式，有条件时可组建规范化公司。还对公司的组建、运行和注意事项等方面进行了论述，并提出煤炭地质系统集团化的设想。  相似文献   

方解石和白云石溶蚀实验热力学模型及地质意义   总被引：15，自引：0，他引：15  

肖林萍  黄思静 《矿物岩石》2003,23(1):113-116

通过碳酸盐（方解石、白云石）溶蚀作用实验室模拟研究，建立了溶蚀作用的热力学模型方程，对埋藏成岩的3种不同温压条件下（348．15K，Mpa ,373．15K，25Mpa，403．15K，30MPa）碳酸盐溶蚀作用进行了定量研究。提出随着温度和压力的升高，碳酸盐溶解反应的吉布春播由能降低，因而溶解反应增强；在相同温度和压力的地质条件下，白云石较方解石更易溶蚀并形成次生孔隙，这为油气生成运移提供了有利的地下空间和通道。  相似文献   

Contribution à l'étude d'une partie du bassin d'Essaouira (Maroc) par sismique réflexionContribution to part of the Essaouira Basin (Morocco) by seismic reflection     

Mohammed Jaffal  Azzouz Kchikach  Jean-Pierre Lefort  Lahoucine Hanich 《Comptes Rendus Geoscience》2002,334(4):229-234

A large number of seismic reflection lines and boreholes have been carried out in the Essaouira Basin by the oil industry. The present study concentrates on the reinterpretation of these data in the restricted area of Khemis Meskala, in order to better characterise the structure of the Cretaceous aquiferous system. The reflector corresponding to the bottom of the Vraconian formation has been identified on the different seismic sections. This horizon, which marks the base of the aquiferous system, was first digitised on time migration sections and then converted to depth sections using a suitable linear velocity law. The isobath map of the bottom of the Vraconian resulting from this study images the 3D geometrical structure of this horizon and shows that it is slightly folded in domes and basins. This document will be useful for rationalising the future hydrogeological researches that will be undertaken in the Khemis Meskala area. <em>To cite this article: M. Jaffal et al., C. R. Geoscience 334 (2002) 229–234.em>  相似文献   

最大效果测度值法研究矿井突水水源   总被引：2，自引：0，他引：2  

洪雷  彭华 《中国煤田地质》2002,14(2):45-46,73

为了快速准确地查清矿井突水水源，排除水患对生产的影响，利用最大效果测度值燕子山矿14-2＃煤层顶板砂岩裂隙水，其导水通道为工作面所在盘区发育的F23和F38正断层。最大效果测度值为矿井防治水工作提供了一个新的思路。  相似文献   

太原边山断裂带地热资源研究   总被引：2，自引：1，他引：2  

侯玉新 《中国煤田地质》2002,14(4):38-41

太原岩溶含水系统主要由东山、北山、西山及盆地岩溶地下水流域所构成,其含水岩系为奥陶系中统,根据系统内150余件水化学资料,对岩溶含水系统的地温场和水化学场特征进行了描述,与水动力场性质是一致的;通过地球化学温标对热储温度的定量计算,表明边山断裂带“历史”上确有地热存在;初步分析研究了边山断裂带地下热水的成因及其赋存规律,认为东、西边山地热分布是不均一的,呈明显的“点”状特征,故地热井施工位置应在第一、二级断裂之间。  相似文献   

论有机质与金属成矿和勘查   总被引：15，自引：1，他引：15       下载免费PDF全文

陈远荣贾国相  戴塔根 《中国地质》2002,29(3):257-262

有机质与金属成矿是一个处于初级研究阶段的地球化学领域。本文对其研究历史进行了回顾，指出了有机质在金属成矿中的主要作用以及有机烃气测量在金属矿产勘查中的初步应用成果。认为该领域的深入研究，可促进成矿作用、成矿过程、成矿规律、气体运移规律和成矿预测的全面认识，对有机地球化学和无机地球化学、固体地球化学与气体地球化学、勘查地球化学与矿床学等不同学科之间的连接和相互渗透将起重要的纽带作用。  相似文献