Morphostructural prognostication of kimberlites in parts of eastern dharwar craton: Inferences from remote sensing and gravity signatures

The varied nature of geophysical signatures encountered in the identification of blocks with favorable setting for emplacement of kimberlites, the major geological hosts of diamonds, has resulted in the development of different criteria for their prognostication. This paper attempts to bring out the association of domal morpho-structural features with kimberlite occurrences. From analysis of an IRS-ID LISS-III satellite image of the Maddur-Narayanpet-Mahboobnagar-Gadwal-Raichur region (latitudes 16° N to 17°15’ N and longitudes 77° E to 78°15’ E) in the eastern Dharwar craton, the surface morphology and structural configuration were obtained. From observed surface correlation of reported kimberlite occurrences with intersecting lineaments within regions of domal morphology, regions with such configuration were delineated as potential kimberlite bearing zones. Using this observation as a criterion, six potential kimberlite zones were delineated: near Sedam, around Maddur, north of Mahbubnagar, north of Raichur, between Raichur and Gadwal and around Gadwal. Subsequently, from reanalysis of available gravity data in a part of the Maddur area, the structural features inferred from image analysis were corroborated. The crustal configuration along a representative profile across a region associated with kimberlite emplacement was obtained to understand the subsurface pattern of its occurrence. Occurrences of kimberlites were found to be localized at intersections of lineaments in regions characterized by upwarps in the Moho and corresponding lows in the gneissic basement.     

Interpretation of Synthetic Aperture Radar (SAR) imagery for geological appraisal: A comparative study in Anantapur district of Andhra Pradesh

The paper describes the details of a comparative study of geological interpretations carried out from Synthetic Aperture Radar (SAR) imagery, Landsat MSS (B & W) imagery and Aerial Photographs, covering 2100 sq km of area in Anantapur district of Andhra Pradesh. The area comprises Peninsular—Gneissic Complex and rocks of Dharwar and Cuddapah Super Groups beside the Quaternary alluvial deposits along the Penneru river and its tributaries. Geomorphologically the areas is represented by denudational, fluvial and structural landforms. The study indicates that the details of the geological and geomorphological maps prepared from SAR imagery and aerial photographs are comparable despite the smaller scale of SAR imagery while the same are not exhibited in Landsat imagery mainly due to its low resolution. Although broad lithological units are possible to be discriminated on SAR as well as aerial photographs, some of the finer rock types viz. gabbroic dykes could be discriminated from the delerite dykes in the SAR imagery due to their different surface roughness. Stereoscopic coverage and enhanced micro-relief of SAR imagery gives better geomorphological details in comparison to aerial photographs. A detailed study of lineaments has also been carried out which shows that in SAR imagery there is over-representation of short lineaments due to enhanced micro-relief and radarshadow effects across the look direction and under-representation of lineaments along the look direction. Landsat imagery is perhaps the best for demarcating lineaments of regional magnitude while aerial photographs are good for depicting shorter lineaments. However, certain lineaments seen in SAR imagery are often not continuously seen on aerial photographs.     

黔西六枝-朗岱地区构造格局及其应力场遥感图像解析

黔西六枝-朗岱地区,矿产丰富,地质构造十分复杂。本文应用恢复区域构造应力场的新方法──“区域构造变形场、应力场遥感图像解析法”,对研究区宏观构造组合及与其有关的横张大节理进行了系统解译。根据“遥感图像解析法”的原理建立了研究区的构造变形场,通过构造变形特征的综合分析,反演了构造应力场。在区域地质研究基础上,对研究区构造控矿规律进行了探讨。     

地质图像的空间/逻辑运算及其应用

本文介绍针对地质图像特殊性来用的空间运算和逻辑运算方法,把“非”、“与”、“或”、“异或”等 常用逻辑运算和数学形态学中的“膨胀”、“剥蚀”、“断开”、“闭合”等空间运算方法引入到地质图像处 理中,并进行若干技术改进,以用于对不同地质特征空间逻辑关系的分析。在地质图像处理基础上, 提取了可供显示、观察和找矿分析的地质变量,对湖南香花岭地区多金属矿进行预测。取得初步效果。     

Lineaments in the coastal zone of Goa

The paper decribes the lineaments in the coastal area of Goa identified on aerial photographs and their correlation with the lineaments reported from the adjoining areas. The majority of lineaments along the coastal part of Goa follows a NW-SE, NE-SW and a few ENE-WSW trends. The NW-SE direction is predominant and corresponds with the regional Dharwarian trend followed by NE-SW trending linears due to cross folding of Dharwar Orogeny.     

Photogeological mapping in parts of Cuddapah basin Kurnool and Prakasam Districts of Andhra Pradesh

An area of 2500 sq. Km. has been covered by photogeological mapping with selected field checks which forms a part of Cuddapah basin in the Kumool and Prakasam Districts of A.P. The rocks exposed in the area belong to the Cumbum and Bairankonda Formations of Cuddapah Super Group. They occur more or less as an alternating sequence. These formations are bound on the east by Dharawar gneisses and on the west by Nandyal Shales. The Bairankonda Formation is predominantly arenaceous with quartzite as the main member, being easily identifiable in the aerial photographs by its characteristic topography, coarse drainage, light grey tone etc. The Cumbum Formation is mainly argillaceous with slate/phyllite as the main member, intercalated with minor quartzite band and is expressed on the photographs in dark tone with dendritic to sub-parellel drainage and occurs relatively at lower elevations, mostly in plains. The Dharwar (Archaean) gneisses underlying the vast plains in the east are recognised by the sandy nature of soil and by the thrusted contact of this unit with the Bairankondas. The Nandyal Shales occupying the large cultivated area in west have a darker tone and a dendritic drainage pattern. They are Upper Kurnool in age. All the litho-units have undergone pre-Kurnool deformation resulting into plunging/doubly plunging antiforms and synforms trending NNE-SSW and a few shear zones and faults. Due to severe deformation a very prominant foliation has developed in the Cumbum unit. Groove lineation has also been developed in the hinge portions of major folds. The magmatic activity in these formations has been witnessed with the emplacement of reibeckite syenite and Kimberlite plugs and veins. Geomorphologically the area may be divided into two prominant units namely (i) Denudational landforms comprising (a) hills, ridges, inselbergs, bornhardts and hogbacks on Bairankonda quartzites and phyllites (b) pediment and dissected pediment on Cumbum Shales and Dharwar gneisses and (ii) Depositional landforms such as (a) alluvial fans and colluvial fans (b) alluvial valley fills along river courses and (c) sand dunes in Dharwar gneisses.     

Geology of the area around Badami,Bijapur District,Karnataka state—A study based on interpretation of remotely sensed data

Geological studies in the area around Badami, Bijapur District, Karnataka, were carried out with the help of Landsat imagery and aerial photographs. The study are forms a part Kaladgi Basin which is located on the northernmost fringes of the exposed Dharwar Craton. Archaen Peninsular Gneiss and intrusive Granodiorite/Granites (≈Clospet Granite) form the basement for the Middle to Late Proterozoic Kaladgi Super Group sediments which are, in turn, overlain in the north by the Upper Cretaceous to Lower Eocene Deccan flood basalt lavas. Geological mapping of the study area and inferences about the structural setup were primarily based on interpretation of the remotely sensed data. The combined interpretative study of Landsat imagery and aerial photographs was instrumental in mapping of the lithostratigraphic units exposed in the study area along with the structures associated with them.     

A Semi-automated GIS Model for Extracting Geological Structural Information from a Spaceborne Thematic Image

This paper presents a semi-automated GIS model for extracting structural information from a spaceborne imaging spectroscopy classification of sedimentary rocks by combining the IS classification with a digital terrain model. The output consists of a database with structural attributes, specifically the dip and strike, of the geological layers. The model was evaluated statistically for its accuracy with promising results, which demonstrate its potential to support field surveys, for geological mapping, for 3D modeling of the subsurface, and for geological spatial analysis.     

无人机遥感在高山峡谷区崩塌地质调查中的应用

为了近距离调查高山峡谷地区崩塌地质灾害的发育情况,并快速提取灾害基本信息,利用无人机遥感对地形条件相当复杂的贵州大方县法启村火车站东侧崩塌群进行了详细的地质调查,探讨了在高山峡谷区利用地质灾害无人机遥感获取高分辨率影像的关键技术方法控制;并利用影像数据处理系统软件构建了DEM和DSM模型,通过中误差精度模型得到调查区模...     

大别山北缘地质找矿中遥感方法的研究

本项工作着重探讨在植被覆盖、地质背景十分复杂的地区，利用遥感信息寻找金矿及其它多金属矿的方法。即从地层岩系、构造及构造交叉部位、蚀变带这三个方面，进行地质找矿专题信息特征提取方法的研究。最后，通过信息提取及影像综合特征，进行遥感地质制图，圈定找矿有希望的地段。     

西藏地质资料信息化建设探讨

本文分析了我区地质资料信息化建设的现状及存在的问题,提出了地质资料信息化建设的对策。     

MapGIS图件校正与GPS定位在地质工作中的应用

在野外地质工作基础上,总结出一套采用MapGIS校正地质图件和针对某一区域设置GPS参数以及二者链接的方法,达到准确编图、图件综合研究的目的,有效地提高了矿产地质调查评价的质量和效率。     

Fracture zones in the Deccan Traps of Western and Central India: A study based on remote sensing techniques

Deccan Trap lavas (Cretaceous to Tertiary), which cover a large area in the Western and the Central India, are generally regarded as structurally undisturbed save for certain areas along the west-coast and the Narmada Valley in Central India. Remote Sensing techniques have given a new dimension to the problem of locating such disturbed areas by virtue of the capacity of aerospace imagery to delineate lineaments, many of which represent structural geological features. Studies carried out in the areas west and north west of Pune, (above and below the western ghat scrap), the Narmada valley region north of Barwah and the Ramakona area of Central India, reveal that these areas are riddled with fractures. The fractures have generally given rise to narrow valley or escarpments. Some of the fractures show displacement along them, while some show intrusive dykes filling them. The fractures in Central India were sometimes found to the extensions of faults traversing the basement. Hence, in the regoins, where the basement is not exposed, they may be suggestive of the structural trends of the concealed basement.     

塔里木盆地遥感区域地质研究

本文着重阐述将塔里木盆地（地块）划分出“内、中、外三环体（带）”的构造新格局;提出该区存在着巨大的“环式弧形构造系统”及其相应的“环式弧形成矿带”与“环式弧形地质环境带”的新论点与新概念,揭示该区矿产资源的成矿、控矿规律,建立行之有效“多位一体”的遥感地质找矿模式;发现环绕塔里木盆地油气、钾盐、煤、铀、金属、建材及宝玉石等５个环状成矿带和罗布泊特大型钾盐矿产基地;以及塔克拉玛干大沙漠区内４大富水区,并提出塔里木地壳具“稳定之中不稳定,不稳定中有稳定”等新的认识。     

云南某县地质灾害与土地利用类型相关性分析

应用法国SOPT-5图像,以ERDASIMAGE软件为平台对研究区土地利用进行监督分类,分析研究区土地利用各个类型与地质灾害的相关性,利用层次分析法确定影响灾害指标及权重。得出居住用地区是地质灾害高易发区,对应了地质灾害易发分区图。     

Perspect and assessment of groundwater resources using remote sensing techniques in and around Choral river basin,Indore and Khargone districts,M.P.

The study area around Choral river basin in the Narmada valley region, forms a part of Indore and Khargone districts of Madhya Pradesh. The geological, geomorphologic, lineament, hydrogeomorphic and groundwater potential zone maps of the study area have been prepared using IRS IC LISS III FCC imagery on 1:50,000 scale. Various litho-units, different land-forms, lineament fabric and hydro-geomorphic units have been worked out by visual interpretation methods and frequent field checks. The integrated hydro-geomorphological map of the study area reveals that the groundwater potential in denudation landforms such as buried pediplains, plateaus, denudational and residual hills is moderate-to-poor. On the other hand, the groundwater occurrence in structural landforms like structural hills, lineaments/faults and narrow gorges is likely to be good to moderate and the depositional landforms namely alluvial plains, valley-fills and meandering-channels favour the accumulation of sub-surface water and, therefore, may be considered as good recharge zones. From the point of view of groundwater occurrence, various hydro-geomorphic units have been classified as high, moderate and low potential zones.     

遥感技术在工程地质选址工作中的应用

通过遥感工程地质选址工作的系统分析，总结了区域地形地貌条件、岩土体条件、地质构造条件、地质灾害发育情况和水文 地质条件等工程地质条件的研究内容和工作方法，指出了遥感工程地质选址工作中应注意的问题。     

Evaluation and integration of ERS-1-SAR and optical sensor data (TM and IRS) for geological investigations

The C-band imaging radar of ERS-1, due to its high sensitivity to terrain surface features, holds tremendous potential in topographic terrain mapping for various applications. This is being examined for geological applications, mainly structural and lithological mapping in a mineral belt of Bihar and Orissa, India. The high image contrast that facilitates structural interpretation and highlights topography on the SAR images, reflects the high sensitivity of the ERS-1-SAR to change in terrain slope in the study area. Extensive lineaments, fold structure and major lithological contacts are easily mappable from the SAR imagery. Many of the lineaments, lithological contacts and fold pattern are mapped equally from optical data (Landsat-TM and IRS-1B FCC). The close association of fold pattern and mineral deposits in the region has necessitated the study of those structures carefully from various remote sensing data products. Synergism between SAR and TM provided useful results regarding structure and lithology of the region. The advantage of SAR in highlighting topography and detecting lineaments are affected to a great extent by the speckle noise and low pixel resolution. The present study shows that future geologic interpretation demands high spatial resolution and efficient data processing technique which reduces the speckle noise more significantly.     

基于地理探测器的北川县地质灾害影响因子定量分析

地质灾害一直是许多学者研究的焦点议题。北川羌族自治县作为2008年汶川地震的极重灾区之一,地质灾害严重影响该地区的生产生活。本文以影响北川县居民点的地质灾害普查数据为基础,从地质地貌、气候等方面,应用地理探测器针对北川县地质灾害的发生进行定量归因。研究结果表明:1)单因子方面年降水量(23.22%)影响力最大,地震烈度(3.70%)最小。2)交互作用大于单因子作用,其中,海拔高度与年降水量交互作用后的解释力达到33.37%。该研究成果可为制定北川县地质灾害防治措施和选择移民搬迁场地提供参考依据。     

基于遥感调查与GIS分析的林芝地区地质灾害评价

利用遥感、G IS技术和其它分析手段,在“递进分析法”(AMFP)理论框架下,利用AHP模型评估各影响因子权重;选用综合指数评价模型求取潜势度、危险度及危害度等区域地质灾害评价指数;借助自建的灾害评价系统,实现了藏东林芝地区的区域性地质灾害预测评价及其可视化表达。研究结果表明:该方法评价结果较为合理;研究方法和试点区预警系统的建设实践对于区域性灾害的预测、预报和防止不仅具有理论意义,也具有重要的现实意义;将人类活动等影响因子量化,不仅缩小了预测区的范围,也突出了地质灾害对人类生存环境的影响。