共查询到20条相似文献，搜索用时 968 毫秒
1.
库鲁克塔格赛马山地区前震旦纪地层,经历了多期变质变形作用改造.通过建立岩石序列和构造变形序列,解析变质变形作用,结合同位素地质年代学研究,厘定出该套地层在阜平、五台、吕梁、四堡、晋宁5个构造期发生的沉积作用、火山作用、变质作用、岩浆侵入活动及产生的构造形迹组合,在此基础上构建区域地质事件表. 相似文献
2.
石榴石-黑云母地质温度计在四川拉拉铜矿床的应用 总被引：7，自引：0，他引：7
在晋宁运动中,拉拉铜矿床区发生了大规模的区域变质作用,由于其变质条件的资料较少,使得人们对矿床的成因机制存在诸多争论.采用石榴石-黑云母地质温度计和多硅白云母地质压力计,结合电子探针分析结果,对矿区内广泛出露的石榴石黑云母片岩进行了研究,得到区域变质作用的变质温度为500～560 ℃,变质压力上限为0.6～0.73GPa,变质程度为高绿片岩相.同时,根据野外观测及室内研究并结合前人工作,认为矿床主要存在两个成矿期次,即火山-喷气沉积成矿期和变质热液成矿期. 相似文献
3.
金山金矿田地质特征及成矿地质作用 总被引：25，自引：4，他引：25
金山金矿田的发现和成功勘探是我国近年地质找矿工作的重大突破。系统介绍了金山金矿田的区域构造背景、矿田构造格架及含矿韧性剪切带特征，探讨了矿床成矿作用，认为该矿床成矿以韧性剪切动力变质作用为主导，其成因属同韧性剪切带型变质热液金矿床。 相似文献
4.
遥感技术在长春市区环境地质与城市稳定性评价中的应用 总被引：3，自引：0，他引：3
本文运用遥感图象对长春市区的地质构造进行了研究。依据线性影象、色调差异及地貌等特征,解译出长春市区的断裂构造及活动性断裂,对长春市规划建设中的地质问题、环境、稳定性等作了阐述,为长春市的开发建设提供了主要的地质背景资料。 相似文献
5.
温泉岩体位于中朝准地台北缘内蒙地轴与燕山沉降带交界的尚义—赤城深断裂中,岩体围岩为中下太古界桑干群变质岩系,其变质程度达角闪-麻粒岩相,原岩为大陆拉斑玄武岩。近年来在该区域发现了许多金矿床(点),空间上与岩体关系密切。 1.岩体地质特征该岩体呈不规则的岩株状出露,北西向廷伸,长19km,宽1.5～4km,岩体分带明显;中心相为钾长花岗岩,肉红色,似斑伏,巨粒花岗结构,斑晶一般3～5cm,个別可达10cm以上,含量40%～50%,以自形钾长石为主,少量自形斜长石,局部 相似文献
6.
吉林省从太古宙至新生代整个地质历史时期都产有金矿床、矿点、矿化点。根据成矿特点、成因类型将区内划分太古宙、元古宙、古生代、中生代、新生代五个金矿成矿期。其中太古宙和中生代成矿期以内生成矿为主,元古宙、古生代成矿期以外生成矿为主,内生成矿为次,新生代成矿期为外生成矿期。各成矿期成矿地喷条件是:一、太古宙金矿成矿期吉林省太古宙地层为一套变质程度较深的变质岩系,亦称绿岩花岗地体。主要出露在南部地台区。包括龙岗群(早期绿岩),为以基、中性火山岩为主的拉斑玄武岩系列;夹皮沟群(晚期绿岩),为以基、中酸性火山岩为主的拉斑一钙碱性系列。它们都含有规模不等的金矿。但主要出现在晚期绿岩一夹皮沟群中,它呈近东西带状展布在早期绿岩(龙岗群)盆 相似文献
7.
桐城作为合肥经济圈成员之一、长江经济协作区腹地,地质资源丰富,地质环境复杂,城市地质资源与城市地质环境统筹协调发展是城市地质工作的重要组成部分,是保障城市健康持续发展的基础.通过查明桐城市地质资源、主要环境地质问题,结合地方发展建设需求,按照均衡桐城市资源开发、环境保护与生态治理,综合统筹桐城市健康持续发展的思路,将桐城市划分生态保护区、特色农业区和工程建设区,并提出地质资源开发与地质环境保护协调发展的对策建议.生态保护区以保护为主,建议发展桐城小花等特色农业,合理开发地质遗迹与矿产资源;特色农业区以农业生产为主,对湿地资源开展保护;工程建设区是桐城市城镇和工程建设最适宜区. 相似文献
8.
矿产资源预测是数学地质的一个重要内容，地质特征法通过分析模型单元中各地质变量对模型产生影响的一些特征及内在联系求得各地质变量的权系数，打破了以往用纯数学的方法求解地质变量权系数问题。在全省的铁矿资源预测中使用了地质特征法，对粤西－粤北的沉积或火山沉积变质型磁铁矿浆进行了Ｇ级资源储量预测，在圈定的２６８个单元中，经过筛选共选得１６个有利于成矿单元，最终预测粤西－粤北区沉积或火山沉积变质型磁铁矿Ｇ级资 相似文献
9.
10.
11.
Recent geological mapping and U/Pb age determinations show that the Kasila Group has many of the characteristics shown by the Limpopo Belt and other high-grade linear metamorphic belts. The Kasila Group appears to form the southwestern periphery of the dominantly low-grade West African Archaean Craton. 相似文献
12.
Variations in metamorphic grade, structural style, isotopic ages and granite geochemistry observed within the Yilgarn craton, and between the Yilgarn and Pilbara cratons, Western Australia, are interpreted in terms of vertical zonation of the Archaean crust. We correlate the gneiss-granulite suite of the Wheat Belt (southwestern Yilgarn) with concealed coeval infracrustal roots of the low-grade granite—greenstone Kalgoorlie terrain (eastern Yilgarn). Differences between the Pilbara, Southern Cross and Laverton granite—greenstone blocks and the downfaulted linear greenstone belts of the Kalgoorlie block are interpreted in terms of deeper-level exposure in the first three blocks.Ultramafic—mafic volcanic sequences in the Yilgarn craton can be divided into at least two major groups — the lower greenstones, regarded as relicts of a once extensive simatic crust, and the significantly younger upper greenstones, believed to have formed within linear troughs following the intrusion of Na-rich granites.At least three major Archaean granite phases occur in Western Australia: (1) 3.1-2.9 b.y. old (recognized to date only in the western Yilgarn and in the Pilbara craton); (2) 2.8-2.7 b.y. old, and (3) 2.6 b.y. old (the two latter phases can only be separated from each other in the eastern Yilgarn, and phase (3) is also identified in the Pilbara). In the main, granites of phases (1) and (2) are Na-rich and those of phase (3) are K-rich. There is evidence for a secular increase in Rb levels and initial 87Sr/86Sr ratios. It is suggested that the K-rich granites grade down into Na-rich granites, and the former were generated by ensialic anatexis resulting in upward migration of K, Rb, U, and Th-enriched magmas.A review of data from several Archaean cratons in other continents suggests that evidence from these regions can be interpreted in terms of the general model of crustal evolution proposed for Western Australia. Implications of this model concerning petrogenesis of Archaean plutonic and volcanic suites, geothermal gradients and tectonic evolution of greenstone belts are discussed. Partial melting associated with mantle diapirism is thought to have given rise to the ultramafic—mafic volcanic cycles. Widespread subsidence and partial melting of this crust yielded Na-rich acid magmas. The development of the upper greenstones was confined to linear belts in a partly cratonized crustal environment. About 2.6 b.y. ago a rise in the geothermal gradient resulted in regional metamorphism and crusctal anatexis which gave rise to the K-rich granites. 相似文献
13.
M.B. Katz 《Precambrian Research》1985,27(4):307-319
The Archaean—Proterozoic crust of many Precambrian terrains consists of two contrasting tectonic units: Archaean cratonic blocks made up of granite—greenstone terrains and Archaean—Proterozoic mobile zones, fold belts and orogens which separate and tend to surround and flow around the cratons. The cratons are relatively rigid blocks, but have a history of ductile and brittle deformations. The surrounding mobile belts are either high-strain, high-grade metamorphic belts or folded basins. Thus, the relatively rigid cratons are surrounded by more ductile zones of mobility. It is speculated that the Archaean cratons are originally separate, although neighbouring ensialic, polygonal miniplate blocks of a single continent which have moved relative to one another according to the mantle controls and the prevailing Eulerian poles, and this mutual jostling has progressively deformed their common boundaries. The deformed boundaries are now the sites of the surrounding ductile and higher strain mobile belts, which are persistent crustal defects, while the cratons represent the more rigid and lower strain cores and relicts, which have stabilized after the Archaean. The mega-scale relationships between the cratons and mobile belts (e.g., East Africa) are compared to the smaller scale micro—meso-scale porphyroclast-matrix structures found in augen gneisses and mylonites. These structural relationships are of vastly different magnitudes (108), but as there exists a continuum on all the intermediate scales they may all be related. Their geometric similarities are interpreted as having a common mechanical—rheological origin. 相似文献
14.
D. A. BREW G. R. HIMMELBERG R. A. LONEY A. B. FORD 《Journal of Metamorphic Geology》1992,10(3):465-482
The Cordilleran orogen in south-eastern Alaska includes 14 distinct metamorphic belts that make up three major metamorphic complexes, from east to west: the Coast plutonic–metamorphic complex in the Coast Mountains; the Glacier Bay–Chichagof plutonic–metamorphic complex in the central part of the Alexander Archipelago; and the Chugach plutonic–metamorphic complex in the northern outer islands. Each of these complexes is related to a major subduction event. The metamorphic history of the Coast plutonic–metamorphic complex is lengthy and is related to the Late Cretaceous collision of the Alexander and Wrangellia terranes and the Gravina overlap assemblage to the west against the Stikine terrane to the east. The metamorphic history of the Glacier Bay–Chichagof plutonic–metamorphic complex is relatively simple and is related to the roots of a Late Jurassic to late Early Cretaceous island arc. The metamorphic history of the Chugach plutonic–metamorphic complex is complicated and developed during and after the Late Cretaceous collision of the Chugach terrane with the Wrangellia and Alexander terranes. The Coast plutonic–metamorphic complex records both dynamothermal and regional contact metamorphic events related to widespread plutonism within several juxtaposed terranes. Widespread moderate-P/T dynamothermal metamorphism affected most of this complex during the early Late Cretaceous, and local high-P/T metamorphism affected some parts during the middle Late Cretaceous. These events were contemporaneous with low- to moderate-P, high-T metamorphism elsewhere in the complex. Finally, widespread high-P–T conditions affected most of the western part of the complex in a culminating late Late Cretaceous event. The eastern part of the complex contains an older, pre-Late Triassic metamorphic belt that has been locally overprinted by a widespread middle Tertiary thermal event. The Glacier Bay–Chichagof plutonic–metamorphic complex records dominantly regional contact-metamorphic events that affected rocks of the Alexander and Wrangellia terranes. Widespread low-P, high-T assemblages occur adjacent to regionally extensive foliated granitic, dioritic and gabbroic rocks. Two closely related plutonic events are recognized, one of Late Jurassic age and another of late Early and early Late Cretaceous age; the associated metamorphic events are indistinguishable. A small Late Devonian or Early Mississippian dynamothermal belt occurs just north-east of the complex. Two older low-grade regional metamorphic belts on strike with the complex to the south are related to a Cambrian to Ordovician orogeny and to a widespread Middle Silurian to Early Devonian orogeny. The Chugach plutonic–metamorphic complex records a widespread late Late Cretaceous low- to medium/high-P, moderate- T metamorphic event and a local transitional or superposed early Tertiary low-P, high-T regional metamorphic event associated with mesozonal granitic intrusions that affected regionally deformed and metamorphosed rocks of the Chugach terrane. The Chugach complex also includes a post-Late Triassic to pre-Late Jurassic belt with uncertain relations to the younger belts. 相似文献
15.
16.
津巴布韦太古宙花岗-绿岩型金矿床受构造的控制,金矿可分为褶皱控矿型、剪切带控矿型、层控型、深成花岗岩控矿型和构造-蚀变岩型等5类。津巴布韦花岗-绿岩型金矿多产于花岗质片麻岩与绿岩带的接触带上,金以自然金或金的硫化物形式产出。金矿成矿时代大致分为(2660±50)Ma和(2410±70)Ma(米德兰德绿岩带北部白钨矿Sm-Nd测年)2个时段,分别与新太古代TTG事件和大岩墙侵入相关。津巴布韦花岗-绿岩型金矿较多,但发现的中-大型绿岩型金矿较少,具有较好的金矿找矿前景。 相似文献
17.
中美合作东昆仑造山带地质填图的启示：填图理念与填图方法 总被引：2，自引：2，他引：0
在中美合作东昆仑造山带地质填图实践的基础上,结合美国地质调查局（USGS）最近完成的地质填图实例的对比分析,初步总结和探讨了美国的地质填图方法和填图理念。结果表明,尽管地球物理和3S技术在地质填图中的应用不断推陈出新,但是地质填图理念、地质填图方法和地质报告风格自USGS成立以来未曾改变。“对所有地质实体按岩性进行划分和详细填图”的地质填图理念伴随USGS走过了130年曲折而艰难的历程。“地质现象引导地质路线”的填图方法是美国地质填图长期采用的方法,但应用于澳大利亚厚层风化壳和加拿大冰雪覆盖区的高精度地球物理填图方法并没有应用到造山带地质填图中,而遥感技术成为造山带基岩区填图的重要技术支撑。美国基岩区高效的地质填图速度并不能用高精度地球物理和遥感技术的应用来解释,已有地质成果的继承与利用、填图工作模式、填图与科学研究的合理定位、简明地质报告和GIS的地质应用才是决定地质填图速度的关键因素。 相似文献
18.
19.
为了研究宁芜北段火山岩盆的矿产资源潜力及空间分布,本文以Landsat8中分辨率遥感数据及Pleiades1高分辨率遥感数据为数据源,综合运用目视解译法和多种遥感图像增强技术,结合区域成矿地质背景,对研究区进行了遥感影像解译,提取了与预测矿种密切相关的线、环、色、带、块遥感五要素。通过分析遥感五要素矿产地质特征与矿产点分布关系表明,研究区内的铁铜硫金矿床及星罗棋布的矿点大部分位于构造岩浆成矿亚带中,受区内北东向、东西向、北西向及其它断裂纵横交叉形成的断裂网格及火山机构控制,大多分布在数条断裂带交汇位置,另有一些分布在断裂带与环形构造的交汇处附近。基于主要的矿点受区内断裂网格及火山机构控制,遥感图像的综合地质信息特征与找矿目标紧密相联,说明了基于遥感图像的综合信息可以作为找矿预测的标志。 相似文献
20.
A metamorphic core complex model is proposed for Khoshoumi Mountain uranium mineralization located in the Bafq–Saghand metallogenic zone of central Iran. Uranium mineralization occurred in the Chapedoni metamorphic complex. Detailed structural analysis of the complex leads to the interpretation that the mineralization is spatially concentrated in a low angle shear zone of mylonitized migmatite, the lower ductile part of the Chapedoni metamorphic complex. The shear zone that has top to the NE sense of shear in the northeastern and southeastern parts of the mountain and top to the WNW sense of shear in the southwestern part is a detachment zone to the Chapedoni Metamorphic Core Complex (CMCC). The Eocene granite is the plutonic core to the CMCC. The shear zone is cut by several NE‐trending left‐lateral strike‐slip faults. This later faulting is interpreted to account for the significant enrichment of uranium in the southern part of the mountain. The bimodal distribution of radiometric data gathered from exploratory drill holes in this part of the mountain constrains this interpretation. That is, the lower value is from the shear zone across the area but the higher value is from the places that the shear zone is cut by the transverse faults. 相似文献