Genesis and distribution of mineral waters as a consequence of recent lithospheric dynamics: the Rhenish Massif,Central Europe     

Franz May  Stephan Hoernes  Horst J. Neugebauer 《International Journal of Earth Sciences》1996,85(4):782-799

Three major, interdependent processes control the genesis and distribution of mineral and thermal waters in the Rhenish Massif, Central Europe: (a) Magmatic processes in the upper mantle provide most of the CO₂ to produce bicarbonate waters in shallow aquifers. (b) Extension of the brittle upper crust enables the ascent of sodium chloride waters. (c) Uplift and erosion shape the massif's relief, which determines the extent of flow systems and the distribution of thermal springs. The chemistry of mineral waters further depends on the aquifers' mineral composition. A comprehensive set of hydrological, chemical, tectonic and geophysical data on the Rhenish Massif has been compiled. It was used to classify the mineral waters and to map the spatial distribution of water properties. The composition of cuttings from several representative wells producing different water types shows that the hydrothermal alteration of the aquifer rocks consists mainly of kaolinization of chlorite and dissolution of feldspar. Numerical transport simulations favour two modes of groundwater flow: topography-driven flow and the pressure-driven ascent of basement brines along active faults. Thermal convection is less important.  相似文献   

内蒙大水清金矿带交代作用及其与金矿化关系     

郑学正  关鸿 《岩石学报》1996,12(3):424-433

大水清金矿带是华北克拉通中有代表性的改造型绿岩金矿之一。它产于前东武纪绿岩地体中安家营子石英二长岩体内外接触带附近的剪切带中。金矿化交代主要受后阶段张性脆裂控制，而剪切带早阶段韧性剪切作用无明显矿化交代，后者主要为成矿交代提供有益的江游交代构造环，境即成矿交代蚀变作用和剪切带同步的两阶段演化模式。大水清金矿带的交代作用有四个阶段：即用长石化阶段，绿泥石化阶段，黄铁绢英岩化和石英－硫化物阶段以及石英－碳酸盐化阶段。第三阶段由五个亚阶段组成：即黄铁绢英岩化和强硅化－强黄铁矿化，石英－多金属硫化物交代，石英－贫扶矿充填交代和细粒黄铁矿充填交代。其中前四个亚阶段是本区金的主要成矿期．当韧性剪切转化为张性脆裂时产生的骤然扩容和伴随发生的交代体系转变为富硅体系的钾交代和石英－硫化物交代是金矿成矿的关键。本文还研究和探讨了该金矿成矿交代流体的性质及交代的物理化学环境。  相似文献   

Self-sedimentation of phytoplankton blooms in the geologic record     

Kurt A. Grimm  Carina B. Lange  Amarpal S. Gill 《Sedimentary Geology》1997,110(3-4):151-161

Understanding the formation of laminated, organic-rich sediments is an essential topic for researchers interested in fossil fuels, biogeochemical cycles, Earth's environmental history and global change. Biologists have very recently demonstrated that some marine phytoplankton blooms actively govern their own sedimentation by the formation of sticky transparent gels that facilitate rapid aggregation, accelerated sinking and efficient export flux. Here we present fossil evidence of unfragmented, low-diversity phytoplankton assemblages preserved as sedimentary laminae and irregular flocs that are attributable to a similar phytoplankton-driven sedimentary mechanism we term ‘self-sedimentation’. The geological evidence suggests that self-sedimentation precludes significant heterotrophic grazing, propels the formation of some conspicuous hemipelagic sedimentary laminae and results in efficient carbon and opal flux to the sediments. We suggest that the self-sedimentation phenomenon may have broad implications for the geological history of biogeochemical cycling, oceanic ecological dynamics, and abrupt atmospheric/environmental change. Broader recognition of the self-sedimentation phenomenon as explicitly defined here is a prerequisite to testing these unconventional hypotheses.  相似文献   

蚀变带元素地球化学成矿预测法──以金龙山微细浸染型金矿为例   总被引：4，自引：0，他引：4       下载免费PDF全文

赵利青 《地质找矿论丛》1997,12(3):41-48

金矿化作用伴围岩蚀变，且多受断裂控制，反映在地球化学上出现某些元素的异常。在已发现一害矿化体并掌握一般控制矿特征的地区，利用已有工程在蚀变带内连续捡块采样，分析有关批示元素，总结有关的地球化学指标，建立地球化学预测模式，对已知矿体及外围异常进行了地球化学评价。  相似文献   

广东莲花山斑岩型钨-金矿床蚀变矿化特征及分带模式     

柳少波  王联魁 《吉林大学学报(地球科学版)》1997,(3)

莲花山斑岩型钨－金矿床蚀变类型可以分作钾化、云英岩化、绢云母化、绿泥石化和青盘岩化。矿化表现为黑钨矿化、白钨矿－硫化物矿化、多金属硫化物矿化及黄铁矿化。蚀变在水平和垂向上具有分带性。由内向外由钾化向云英岩化、叠加蚀变带、绿泥石化＋绢云母化、青盘岩化转化。由浅向深，钾化增强，云英岩化减弱，被叠加蚀变带和绿泥石化及绢云母化所代替。矿化由内向外表现为由黑钨矿化向白钨矿化、多金属硫化物矿化、黄铁矿化转变，由浅向深由钨矿化转变为金矿化及多金属硫化物矿化。与典型斑岩型矿床蚀变分带对比，莲花山斑岩型矿床不同原岩类型蚀变特征变化较大，矿化则表现出富钨、金贫铜及钨金共同产出的特征。  相似文献   

欧亚大陆及西太平洋边缘海岩石圈结构   总被引：15，自引：0，他引：15  

朱介寿  曹家敏  蔡学林  严忠琼 《地球科学进展》2004,19(3):387-392

根据欧亚大陆及西太平洋地区天然地震、人工地震及其他地学资料，采用多学科多手段进行综合反演，建立欧亚大陆及西太平洋边缘海岩石圈模型，对欧亚大陆及西太平洋边缘海岩石圈软流圈结构进行研究。探讨欧亚大陆及西太平洋边缘海板块结构及深部动力学问题。  相似文献   

表生风化作用下多年冻土土壤的理论粒径分布     

Igor E. Guryanov 《冰川冻土》2004,26(Z1):70-75

The paper discusses the distinctive features of grain size distribution of permafrost soils formed under conditions of continental lithogenesis and cryogenic weathering of rocks. As a functional consequence of surface erosion of mineral particles, the log-normal distribution of the density function of grain size is derived confirmed for any conditions and sediment types.  相似文献   

Controls on modern alluvial fan processes in the central Alps,northern Italy     

Giovanni B. Crosta  Paolo Frattini 《地球表面变化过程与地形》2004,29(3):267-293

Alluvial fan development in Alpine areas is often affected by catastrophic sedimentary processes associated with extreme ?oods events, causing serious risks for people living on the fans. Hazard assessment in these areas depends on proper identi?cation of the dominant sedimentary processes on the fans. Data from a set of 209 alluvial fans from the central Alps of Italy are presented in this paper and analysed with the help of various statistical techniques (linear regression, principal components analysis, cluster analysis, discriminant analysis and logistic regression). First, we used modern sedimentary facies and historical records (?ood events since 15th century), to distinguish between the two dominant sedimentary processes on alluvial fans: debris ?ows and stream?ows. Then, in order to analyse the main controls on past and present fan processes, 36 morphological, geological and land‐use variables were analysed. As with observations for arid‐environment fans, catchment morphology is the most in?uential factor in the study area, whereas geology and land use are minor controls. The role of climatic change and landsliding within the catchments also seems to be very important and is discussed. Statistical techniques also help in differentiating groups of alluvial fans by sets of controlling factors, including stage and type of evolution. Finally, by using discriminant analysis and logistic regression, we classi?ed alluvial fans according to the dominant sedimentary process, with a success rate ranging between 75 and 92 per cent. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

土壤的冷生构造及其对阿拉斯加土地利用的意义     

C. L Ping  M.T. Jorgeson  Y.L. Shur 《冰川冻土》2004,26(Z1):1-7

Cryogenic structure (patterns made by ice inclusions) in seasonally frozen and permafrost-af-fected soils result from ice formation during freezing. Analysis of cryogenic structures in soils is essential to our understanding of the cryogenic processes in soils and to formulating land use management interpretations. When soils freeze, the freezing front moves downward and attracts water moving upward resulting in mainly horizontal lenticular ice formation. Platy and lenticular soil structures form between ice lenses in upper active layer. The reticular soil structure usually forms above the permafrost table caused by freeze-back of the permafrost. The upward freeze-back resulted in platy soil structure and the volume changes following the annual freeze-thaw cycle resulted in vertical cracks. The combined result is an ice-net formation with mineral soils embedded in the ice net. The upper permafrost layer that used to be a part of the active layer has an ice content exceeding 50% due to repeated freeze-thaw cycles over time. The mineral soils appear in blocks embedded in an ice matrix. The permafrost layer that never experienced the freeze-thaw cycle often consists of alternate layers of thin ice lens and frozen soils with extreme hard consistence and has relatively lower ice content than the ice-rich layer of the upper permafrost. Ice contents and thaw settling potentials associated with each cryogenic structure should be considered in engineering and land use interpretations.  相似文献   

The Activity of Major Faults and the Hydrothermal Alteration Zone at Tianchi Volcano of Changbaishan     

Liu Mingjun 《中国地震研究》2004,18(3):253-262

It is found by field investigation that the near horizontal top surface of the brown or brick-red hydrothermai alteration zone varies obviously in elevation at different sections of the same layer on the caldera‘s inner wall of Tianchi, with that at the north section near the Tianwen Peak about 110 m higher than that at the south near the Jiangjun Peak in Korea. The top surface of the hydrothermai alteration zone can be taken as key horizon to tectonic movement. The difference indicates that the total uplift height of the NW wall of the Liudaogou-Tianchi-Jingfengshan fault, the principal fault trending NE at Tianchi, is bigger than that of the SE wall ever since the occurrence of hydrothermal alteration. This also explains why the topography in the northwest side of Tianchi is steeper and with more developed river system than in the southeast. The uplifting of the northeastern wall is bigger than that of the southwest along the principal NW-trend fault, namely, the Baishanzhen-Tianchi-Jince fault. It is observed from characters of hydrothermal alteration and the palaeoresiduum, that the recent vertical movement rate along the principal NE-trend fault is larger than that of the principal NW-trend fault. The two faults intersect at Tianchi, dividing the volcano into 4 blocks, with the uplift magnitudes decreasing successively in the order of the north, the west, the east and the south block. The biggest uplift of the north block corresponds well to the shallow magma batch in the north of Tianchi observed by DSS and telluric electromagnetic sounding, and etc. and they may be related with the causes.  相似文献