Clogging microstructures in the vadose zone—laboratory and field studies     

Katarzyna Skolasińska 《Hydrogeology Journal》2006,14(6):1005-1017

Long-term water infiltration into porous media, like clastic deposits, causes colmatage (clogging), which is expressed by the decrease of permeability. It is caused by progressive filling of pore spaces with fine particles carried in suspension (mechanical colmatage) and minerals precipitated from water (chemical colmatage or biochemical colmatage, when the process is affected by bacterial activity). Although this material is introduced into the sediment after deposition, it does not destroy the primary framework of it but it only coats grains and fills voids. This process results in some characteristic microstructures that are called ‘clogging microstructures’. The research included: (1) experiments on sands exposed to mechanical colmatage in laboratory conditions, which aimed to describe clogging microstructures and to examine the effects of grain size distribution on the rate and degree of clogging; (2) field and laboratory studies of deposits in which colmatage occurred in natural conditions in the infiltrating water intake ‘Dębina’ in Poznań, Poland. The main goal of the research was to identify post-depositional changes that took place in fluvial deposits affected by forced river water infiltration in the Warta River valley. Examples are presented of clogging microstructures formed in deposits affected by colmatage in the laboratory and in natural conditions.

Katarzyna SkolasińskaEmail: Fax: +48-618-296001

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Seismic imaging and potential field modelling to delineate structures hosting VHMS deposits in the Skellefte Ore District, northern Sweden   总被引：1，自引：0，他引：1  

A. Malehmir  A. Tryggvason  C. Juhlin  J. Rodriguez-Tablante  P. Weihed   《Tectonophysics》2006,426(3-4):319-334

The Skellefte District in northern Sweden is a roughly 150 by 50 km² large early Proterozoic massive sulphide belt. Based on high-resolution reflection seismic data along two parallel seismic profiles, potential field modeling has been carried out and two geologic cross sections have been constructed that are consistent with the available geophysical data as well as surface geologic observations. The combined modelling suggests that the Kristineberg deposit occurs on the northern limb of a regional E–W striking syncline. The interpretations help to identify new prospective areas, both down-plunge from known ores, and on the ore-bearing horizon on the southern limb of the syncline. The new results suggest that the post-orogenic Revsund granites can be divided into two major types of intrusives, those which are intruded as domes/stokes with a maximum present day thickness of about 3–3.5 km and those which are intruded as thin sheets, with a maximum thickness of a few hundred meters. The margins of the intrusions are generally inclined inwards, suggesting that the current erosion level is near the middle, or toward the base, of the granites. The contact between the Skellefte volcanic rocks and the Bothnian Basin has been interpreted as a thrust fault. We also suggest that crustal thickening predates the Skellefte volcanism and that the interpreted Bothnian Basin rocks are either a structural basement or a separate terrane to the Skellefte volcanism. Diffraction patterns in the reflection seismic data can be interpreted as originating from either a mafic–ultramafic intrusion or a mineralization zone, similar to observations elsewhere in the world. The results obtained in this study have greatly improved our understanding of the tectonostratigraphic framework and architecture of the poly-deformed c. 1.9 Ga Skellefte VHMS belt and is a key step towards building a 3D geological model in the area.  相似文献   

Identification of Quaternary subsurface glacial deposits using 3D databases and GIS     

《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(2):90-95

To solve the problem of handling numerous data from drillings and geophysical surveys for specific information of subsurface geological formations, the use of databases and geographic information systems (GIS) is demonstrated. Geological formations are in 3D and commercial GIS packages are normally in 2D. This problem is solved here by a 1D database of the layering of the drillings and export of query results from the database to a 2D GIS. The queries will ask for grain size and altitude for the actual sedimentary layers. To include point data from ground penetrating radar (GPR) data survey profiles in a 2D GIS, a stepwise technique of dynamic segmentation has been developed. The points are digitized along sedimentary boundaries from 2D GPR profiles. The concept was applied on a small area of glacial sediments in Telemark, Norway. Results from the processes were clustering of points with properties connected to specific geological formations. The clustering subsurface geological formations were moraine ridges, a diamict layer, gravel and coarse sand above and below the diamict layer, till above bedrock, and glaciomarine deposits of gravel and sand. Information about extension of these geological formations is useful and essential for modelling of sedimentary environments and for aquifer modelling.  相似文献   

云南北衙斑岩-矽卡岩金铜矿床三维可视化建模与应用          下载免费PDF全文

周放  王保弟  贺娟  郝明  王鹏 《中国地质》2022,49(1):241-252

[研究目的]位于金沙江—红河巨型构造-岩浆成矿带中段的北衙超大型矿床(已探明金151.28 t,铜22.17万t),是三江特提斯成矿域东段典型的斑岩-矽卡岩型金多金属矿床.近年来,矿床浅部地质结构与资源状况已得到初步揭示,但是其深部地质结构、深部控矿构造及深部找矿潜力还不清楚,制约了深部的找矿发现.[研究方法]本研究以...  相似文献   

东北非VMS矿床地质特征与研究进展     

向文帅  赵凯  曾国平  李福林  王建雄  胡鹏  张紫程 《地质通报》2022,(1):129-140

东北非地区主要包括埃及、苏丹、厄立特里亚和埃塞俄比亚.该地区金、银、铜、锌等矿产资源丰富,主要矿床类型为VMS(火山成因块状硫化物)矿床.自发现Ariab、Bisha等大型VMS矿床以来,各国矿业公司在东北非地区开展勘探和开发,并新发现大量矿床,铜、金等矿产资源量不断增加.通过对区域内各国VMS矿床的勘查、研究进展进行...  相似文献   

康滇地轴西缘矿床成矿系列及区域成矿模式初探   总被引：2，自引：0，他引：2  

赵支刚 《四川地质学报》1993,(1)

本文在前人资料的基础上应用成矿系列理论,对康滇地轴西缘成矿规律进行了归纳和总结,初步划分出矿床成矿系列并建立了区域成矿模式,指出今后找矿的主攻类型。  相似文献   

青海锡铁山铅锌矿床类型刍议   总被引：3，自引：0，他引：3  

冯志兴  孙华山  吴冠斌  王玉奇 《地质论评》2010,56(4):501-512

锡铁山铅锌矿床是我国大型块状硫化物矿床之一。该矿床类型认识长期存在争议,目前已有越来越多学者将其视为SEDEX型矿床。本文在近年来块状硫化物矿床成矿构造背景研究进展归纳整理的基础上,结合柴达木盆地北缘早古生代区域地质研究进展,提出锡铁山矿床的成矿构造环境不是以往认为的陆内裂谷,而是活动大陆边缘弧后/间盆地裂谷。鉴于成矿构造环境变化,锡铁山矿床类型也应作出相应调整,由原来的SEDEX型矿床改为VSHMS型矿床。这样做可以达到三个方面的目的:其一,有利于解决现存的成矿构造背景认识与区域地质认识不一致的矛盾;其二,有利于保障本区目前和未来大规模展开的区域成矿研究及找矿勘查评价建立在正确的成矿背景认识前提之下;其三,将矿床类型划分与成矿构造背景相结合,进而用矿床类型揭示构造背景,体现了矿床研究为地球系统科学服务的宗旨。  相似文献   

中蒙边境阿尔山地区钼多金属矿的主要类型及找矿方向   总被引：1，自引：0，他引：1  

解惠 《地质与勘探》2010,46(1):49-58

阿尔山地区处于中蒙边境南戈壁-阿尔山-多宝山钼多金属成矿带上,具有良好的找矿前景。但由于区内工作程度低,多年来找矿一直没有很大突破。笔者结合1:50000矿调工作,按成因类型把区内钼多金属矿划分成3种,并重点对斑岩型钼多金属矿进行详细介绍并与蒙古国南戈壁、黑龙江多宝山类似矿床进行了对比研究,同时重点对区内斑岩型钼多金属矿的成矿地质条件及找矿方向进行了研究。文章通过深入研究后认为本区可能具有找到大型斑岩型钼多金属矿的潜力,其它2种类型的钼多金属矿可能具有找到中小型钼多金属矿的潜力。总之,阿尔山地区具有良好的找矿前景。  相似文献   

与溢流性玄武岩有关的铜镍硫化物矿床地质地球学特征与成矿潜力分析——以广西罗城县清明山铜镍硫化物矿床为例   总被引：1，自引：0，他引：1  

刘继顺 《地质与勘探》2010,46(4)

广西罗城县清明山铜镍硫化物矿床,镁铁质-超镁铁侵入岩与玄武岩广泛分布,时空关系密切,两者岩石化学成分丰度相同,均具有富MgO、贫SiO2、TiO2、K2O的特征,微量元素、稀土特征相同,具有成因上的联系和有先后演化的特征。含矿镁铁质岩体岩石化学成分SiO2含量为42.68～50.63%,K2O含量0.052～2.54%,TiO2含量0.326～0.63%;微量元素Rb,Ba富集,Ta、Nb亏损的特征,稀土元素含量中等ΣREE=27.56～52.36(10-6),ΣLREE/ΣHREE=7.17～12.31,(La/Yb)N=2.48～8.17,δEu=0.93～1.43,轻稀土富集,配分曲线右倾,无δEu负异常;硫同位素δ34S值4.52～17.04‰。镁铁质-超镁铁岩和铜镍硫化矿主要物质来源于幔源,有壳源混染;地质特征、地球化学特征等与美国Duluth铜镍硫化物矿床特征相同,为国内一种新的与溢流玄岩有关的岩浆铜镍硫化物矿床,资源潜力巨大。  相似文献   

新疆哈密黄山东铜镍硫化物矿床成岩成矿作用   总被引：7，自引：1，他引：6  

胡沛青  任立业  傅飘儿  张铭杰  李晓亚  秦宏毅 《矿床地质》2010,29(1):158-168

黄山东铜镍硫化物矿床赋存于橄榄岩、苏长岩、辉长岩和闪长岩组成的镁铁-超镁铁质杂岩体中,赋矿岩体包含至少4套岩石组合。不同类型岩石微量元素和稀土元素原始地幔标准化配分模式指示,该矿床明显亏损Nb、Ta、Zr、Hf等高场强元素和Cr元素,富集Sr及大离子亲石元素;(La/Yb)N=1.08～2.70,δEu=0.50～2.57;含矿岩石Cu/Pd比值和Ti/Pd比值大于原始地幔值,表明不同类型岩石是高镁玄武质岩浆在深部分异结晶演化的产物。根据橄榄石和全岩化学组成可估算出母岩浆MgO含量约为12%。成矿岩浆深部演化过程中,富硅的地壳混染组分和外来流体的加入可能促成了岩浆中的硫饱和;深部熔离的不混溶硫化物珠滴被上升岩浆携带,富集在橄榄岩和苏长岩的底部。  相似文献