Progress in the Study of Deep Profiles of Tibet and the Himalayas (INDEPTH)

This paper introduces 8 major discoveries and new understandings with regard to the deep structure and tectonics of the Himalayas and Tibetan Plateau obtained in Project INDEPTH, They are mainly as follows. (1) The upper crust, lower crust and mantle lithosphere beneath the blocks of the plateau form a "sandwich" structure with a relatively rigid-brittle upper crust, a visco-plastic lower crust and a relatively rigid-ductile mantle lithosphere. This structure is completely different from that of monotonous, cold and more rigid oceanic plates. (2) In the process of north-directed collision-compression of the Indian subcontinent, the upper crust was attached to the foreland in the form of a gigantic foreland accretionary wedge. The interior of the accretionary wedge thickened in such tectonic manners as large-scale thrusting, backthrusting and folding, and magmatic masses and partially molten masses participated in the crustal thickening. Between the upper crust and lower crust lies a large detachment (e.g     

西准噶尔达尔布特蛇绿岩带萨尔托海岩体深部结构、构造特征:地质与地球物理证据

西准噶尔地区分布多条蛇绿混杂岩带,地表地质已有大量研究成果,但蛇绿岩深部结构构造研究相对薄弱,一定程度上制约了该地区地质构造演化的深入认识.为此,本文选取达尔布特蛇绿混杂岩带萨尔托海段开展了大比例尺地质填图配套地面重力、磁法和可控源音频大地电磁测深(CSAMT)等综合测量,获得了该蛇绿岩体地表分布、接触关系以及深部的磁性、密度结构和电性特征,精细刻画了蛇绿岩的深部结构与构造,并进一步分析了其侵位机制和动力学过程.萨尔托海蛇绿岩具有低重力、高磁性和变化范围较宽的电阻率值,岩体整体以构造岩块状产出,表现出挤压逆冲、走滑剪切、破碎蚀变等变形变质.本文及前人研究成果表明,萨尔托海岩体是在近东西向挤压兼走滑应力作用下以斜向楔冲形式构造就位,并进一步受到后期左行走滑和岩浆作用的叠加改造.结合区域构造演化,西准噶尔蛇绿岩的构造侵位与晚石炭世板块汇聚背景下残余洋盆的收缩有关,持续的挤压兼走滑应力使残余洋盆下伏基底蛇绿岩沿断裂构造侵位于上覆沉积地层.     

Landslide zoning in a part of the Garhwal Himalayas

 The Himalayas are undergoing constant rupturing in the thrust belt zone in the Garhwal Himalayas, due to which earthquake and mass movement activity is triggered. These processes of mass movement and landslides have been constantly modifying the landscape. Landslides are one of the indicators of the geomorphological modifications taking place in this active and fragile terrain. This work is aimed at providing another example of landslide susceptibility mapping based on geological and geomorphological attributes. The data collected from aerial photographs, topographic sheets and the image suggests that there is a correlation between the distribution of landslides and some of the geological and geomorphological factors, for example, the distance from an active fault, relative relief and slope. Parameters like factor of safety, altitude, relief, slope and the distance from the fault lineament have been included in the study. A rating system has been applied to the factors for arriving at a quantitative estimate of landslide susceptibility for each physiographic unit. Since terrain classification forms the foundation of this work, the entire study can be grouped into two sequential activities: (1) the terrain classification and (2) landslide susceptibility mapping. The result is the landslide susceptibility zoning map presented. The landslides have not been classified with respect to time and may represent the final result of the on-going geological, geomorphological and seismic activity since the Holocene period or late Pleistocene time when the glaciers retreated. The area chosen for the study lies between Badri gad and Barni gad in Yamuna valley region of the Garhwal Himalaya where a very large scale investment is in the pipe line for Hydroelectric power generation. Received: 12 August 1993 · Accepted: 13 January 1998     

Sedimentology and genesis of the Cenozoic sediments of northwestern Himalayas (India)

The paper discusses at length the provenance and the environments of sedimentation of the Cenozoic sediments exposed in the northwestern sector of the Himalayas. The results are based on detailed sedimentological (including mineralogical, petrographical and petrochemical) investigations of more than 3,000 representative samples. It is concluded that the detritus of the Cenozoic formations was derived mainly from metamorphosed rocks exposed in the adjacent Himalayan regions. A comparatively smaller proportion of the sediments was contributed by acid plutonic, volcanic and sedimentary rocks. The detritus of the oldest unit of the Cenozoic sequence was deposited in shallow marine waters. The remaining formations represent the accumulations of nonmarine environments fluctuating in space and time.     

Tectonic Fragmentation and Geodynamic Regime of Elbrus and Kazbek Volcanoes (Central Caucasus,Russia): Results of the Deep Geophysical Research

Geotectonics - A comprehensive analysis of instrumental data was carried out to establish indicators of the geodynamic conditions of interaction between the Scythian Plate and the collage of...     

Relationships of Surface Geological and Geophysical Characteristics with the Deep Structure of the Mid-Atlantic Ridge According to Seismic Tomography Data

Geotectonics - A retrospective analysis of seismic tomography models with different levels of detail along the Mid-Atlantic Ridge (MAR) has shown that mantle inhomogeneities depicted by variations...     

综合物探方法在深部找矿工作中的应用

在深部矿产资源勘查中,地球物理勘探是最重要的技术手段之一,应用综合物探方法在寻找深部金属矿中取得了显著的地质效果。通过几个典型案例的介绍,综合物探在深部找矿工作中具有较高的推广应用价值。     

Integrated Geophysical Works on the Kozlovka Anomaly (Kaluga Region)

This work presents integrated geophysical studies that were carried out to identify the nature of the intense magnetic anomaly detected by the results of land surveying on the right bank of the Slushka River in the territory of the Yukhnovskii district of Kaluga Region. The comprehensive interpretation of the geophysical data and the laboratory measurements of the core made it possible to determine the nature and parameters of the anomaly-forming object that is located in the upper part of the section; it consists of loams that contain such magnetic minerals as greigite, pyrrhotite, and magnetite.     

Structure and petrology of mylonite and related rocks from the Lesser Himalaya,Garhwal, India

In the Lesser Himalayan region of Garhwal, an elongate, NW-SE trending zone of mylonitic rocks is developed along the Singuni Thrust within the metasedimentary formation of the Deoban-Tejam Belt. Detailed petrography of various mylonitic rocks indicates that a quartz and felspar porphyry was emplaced along the Singuni Thrust. This was initially metamorphosed in the almandine-amphibolite facies before profound ruptural or cataclastic and crystalloblastic deformation evolved mylonitic rocks in the green schist facies. Southwesterly dipping foliation and an equally prominent mica lineation plunging in the same direction are developed in these mylonitic rocks. The quartzite is also intensely cataclastically deformed in the green schist facies and is highly schistose with a prominent mica lineation normal to the trace of Singuni Thrust, Uttarkashi Thrust and Main Central Thrust in the ‘a’ direction of tectonic transport. In quartzite and mylonitic rocks, a probable contemporaneous development of the metamorphic and structural elements has been postulated along the Singuni Thrust during large scale tectonic movements. Normally exposed Gamri Quartzite is more metamorphosed near its base along the Singuni Thrust and Uttarkashi Thrust while the intensity of deformation increases near the top of normally exposed quartzite along the Main Central Thrust and, thus, signifying the role of thrusting in cataclastically deforming the rocks and contributing to the phenomenon of widespread reversal of metamorphism in the Lesser Himalaya.     

Geological and Geophysical Studies of the Charlie Gibbs Fracture Zone (North Atlantic)

Doklady Earth Sciences - The geological and geophysical data obtained during the 50th cruise of R/V Akademik Nikolaj Strakhov on the Charlie Gibbs megatransform system structure...     

综合物探解决黄土区煤田复杂地质问题

山西某矿位于构造堆积盆地，属黄土匠陵地貌，区内被第四系黄土覆盖，为解决该矿地质构造及水文地质问题，采用三维地震勘探与瞬变电磁法、直流电测深法相结合的勘探方案。利用三维地震勘探解决目的层赋存形态及其地质构造问题，再利用瞬变电磁法进行平面控制，以使平面及深度解释误差达到勘探要求；应用直流电测深法及瞬变电磁进行勘探，在正反演解释的基础上对其资料综合分析、对比，并结合三维地震资料，确定地质构造的富水及导水性。     

黑龙江省东部当壁镇-宝清县综合地球物理剖面的地质解释

依据作者2005年在野外布设并实测的黑龙江省东部当壁镇-宝清县（简称DB02）地球物理（主指重力与电法）剖面资料,分析了研究区的地球物理场特征。根据重力欧拉反褶积计算成果并参考电性资料,DB02剖面内可划分出9条断裂、7个构造分区,并对沉积基底及油气远景区进行了计算和预测。结果表明:勃利盆地东部电性中低电阻率区不利于生油,而是一个寻找煤层气的有利地区;宝清坳陷上部有推覆构造,下部低阻区是寻找油气藏极为有利的构造区。     

地质与地球物理综合找矿预测——以刘家坪VMS型铜锌矿床为例

地质与地球物理方法的综合找矿预测是以成矿模式和地球物理理论为基础,将矿床（地质体）成矿理论、地球物理、地球化学、遥感等信息进行综合分析的工作方法（张宝林,2004;廖桂香,2007）。矿床的形成经历了特定的成矿条件和成矿过程,并赋存于一定的地质环境中,地球物理信息是对地质体的空间分布特征的反映,不包含成矿的直接信息,因此,在成矿预测与找矿过程中,要以地质成矿理论为基础,充分挖掘地球物理、地球化学等的综合数据,尽可能地排除干扰,提取有利信息（申萍等,2011;陈思宇,2014）。本文以刘家坪VMS型铜锌矿床为例,介绍综合地质-地球物理方法在多金属硫化物矿床中的应用,建立了VMS型矿床综合找矿模式,为其他地区的找矿工作提供一定的理论与实践依据。     

Structure, Composition and Evolution of the South Indian and Sri Lankan Granulite Terrains from Deep Seismic Profiling and Other Geophysical and Geological Investigations: A LEGENDS Initiative

We here argue the need for a multidisciplinary, integrated geophysical/geological survey across southern India and Sri Lanka, part of the largest exposed Neoproterozoic high-grade metamorphic terrain in the world. The purpose is to stimulate deep seismic profiling and other geophysical and geological investigations in order to better understand the structure, composition and evolution of a keystone of Precambrian continental crust and the role it played in the amalgamation and subsequent break-up of the Gondwana supercontinent. Of particular importance is that this lithospheric fragment records a 2 billion year long history of magmatism, sedimentation, deformation and metamorphism and now exposes at the surface rocks that once formed at depths of 30 km or more and that record unusually high metamorphic temperatures of up to 1000°C. Modern geophysical data should help to determine what lies underneath these high-T surface rocks and whether the terrain consists of structural distinct subunits separated by (now hidden) sutures. It is likely that the crustal-scale structures generated during the formation of the SGT may extend to other, now dispersed, segments of the Gondwana landmass and their identification in geophysical data will provide a fresh basis for reconstructing the process of supercontinent assemblage and break-up.     

阿尔金-昆仑山地区区域地质调查成果与进展

1地层古生物1.1元古代瓦石峡幅、阿尔金山幅将原划古元古界“阿尔金群”的变质岩系解体为变质表壳岩和变质深成侵入岩2部分,并按岩性组合、变形变质特征等将变质表壳岩进一步划分为米兰岩群和阿尔金岩群。米兰岩群经历了中—高压角闪岩相—麻粒岩相变质作用的改造,而阿尔金岩群经历了绿片岩—角闪岩相变质作用的改造,二者呈断层(或韧性剪切带)接触关系。苏吾什杰幅将前长城系原阿尔金群解体为4部分,除古生代基性—中酸性侵入岩外的部分为由变质古侵入体、变质表壳岩和含高压超高压变质岩地质体的多类构造岩片组成的构造杂岩,称其为阿尔金杂…     

Surface Geophysical Methods used to Verify the Karst Geological Structure in the Built-up Area: A Case Study of Specific Engineering-Geological Conditions

This article presents a research study of complex limestone karst engineering-geological conditions in the municipality Valaská near Banská Bystrica in Slovakia. The aim of the study is to demonstrate the impossibility of spatial identification of cave spaces using surface geophysical methods due to the specific engineering-geological conditions of a thick surface layer of anthropogenic fill containing highly heterogeneous anthropogenic material. Its maximum thickness is 3 m. Another specificific condition of the study area is its location in the built-up area, due to which the applicability of geophysical methods was limited. The article contains methodological recommendations to be used in analogous geological conditions with karst structures topped with anthropogenic fill, which complicates the identification of cave spaces. The recommended solution herein is the identification of the cave system using underground mapping of the karst and its projection onto the surface for which surface geophysical methods have been combined.     

Landslide susceptibility zonation of the Chamoli region, Garhwal Himalayas, using logistic regression model

A remote sensing and Geographic Information System-based study has been carried out for landslide susceptibility zonation in the Chamoli region, part of Garhwal Himalayas. Logistic regression has been applied to correlate the presence of landslides with independent physical factors including slope, aspect, relative relief, land use/cover, lithology, lineament, and drainage density. Coefficients of the categories of each factor have been obtained and used to assess the landslide probability value to ultimately categorize the area into various landslide susceptibility zones; very low, low, moderate, high, and very high. The results show that 71.13% of observed landslides fall in 21.96% of predicted very high and high susceptibility zone, which in fact should be the case. Furthermore, lineament first buffer category (0–500 m) and the east and south aspects are the most influential in causing landslides in the region.