地矿部“七五”深部地质地球物理综合研究的重大成果——地学大断面简介

全球地学断面计划(GGT)是80年代国际岩石圈计划后五年的主要任务.中国岩石圈计划全国委员会下设了GGT协调组,由地矿部牵头(赵文津研究员任组长)与石油部、中科院、国家地震局等四个部门共同设置了11条一级地学大断面,它们跨越和控制了我国主要构造(见图).全部完成后将为研究我国岩石圈格架打下基础,为研究矿产分布规律和减灾提供深部依据.     

全球地学断面(GGT)地理信息系统的编码技术

依据全球地学断面的特点 ,以及《数字化地质图图层及属性文件格式》和《GGT数字化指南》等标准 ,研制一套全球地学断面地理信息系统的编码标准 ,为建立中国乃至全球地学断面地理信息系统设置主题、分层标准和命名规则 ,以及实体编码标准 ,并把它们应用于中国地学大断面三维地理信息系统的建立中。该编码标准为地学断面信息系统的建立 ,为深入研究大陆岩石圈结构构造、地球动力学、物质成分及不同地学断面的对比 ,进而建立大陆岩石圈的三维结构模型具有重要意义     

基于MAPGIS平台的中国地学断面数字化图形库的建立

地学断面积累了丰富的地质、地球物理和地球化学等综合资料,从中得出的地学信息是提供科学决策、促进社会科技事业和生产力发展的依据.在MAPGIS软件基础上的中国地学断面数字化图形库的建立过程中,地学断面中的每一个实体,在颜色、符号以及线型等方面都被规划统一.地学断面中的特征主题进行了层名划分以及层名、实体的编码,形成分层标准和编码准则.利用MAP-GIS的编辑子系统和Access关系数据库软件,建立了中国地学断面的空间数据库和属性数据库,并将它们联接起来,从而建立了整个中国地学断面数字化图形库.     

基于MAPGISG平台的中国地学断面数字化图形库的建立

地学断面积累了丰富的地质，地球物理和地球化学等综合资料，从中得出的地学信息是提供科学决策，促进社会科技事业和生产力发展的依据。在MAPGIS软件基础上的中国地学断面数字化图形库的建立过程中，地学断面中的每一个实体，在颜色，符号以及线型等方面都被规划统一。地学断面中的特征主题进行了层名划分以及层名，实体的编码，形成分层标准和编码准则。利用MAPGIS的编辑子系统和Access关于数据库软件，建立了中国地学断面的空间数据库和属性数据库，并将它们联接起来，从而建立了整个中国地学断面数字化图形库。     

前言

<正> 第2号中国地学大断面西藏亚东至青海格尔木线的工作,以地质矿产部为主,有地质矿产部和中国科学院所属的8个研究及教学单位65位研究人员参加,自1987年开始,按照计划中的12个研究课题(专题)分别进行工作,现已进入编写说明书和专题研究报告阶段。为了使阶段性成果能及时广为交流,现由第2号大断面负责单位中国地质科学院岩石圈研究中心将12个专题组已完成的27篇文章,连同全球大断面协调委员会主席蒙格尔教授编写的“全球地学大断面编图指南”汇编出版。     

中国地学断面CorelDRAW图形数据库资源整合综合研究

整合了历时数年(2001—2006)数字化研究取得的中国全部11条地学断面图各种专业图件的CorelDRAW图形数据资源及其说明书。参照国际全球地学断面(GGT)数字化编图指南,独立研制了全球地学断面图的GGTCorelDRAW制图色盘和模板,为应用和普及制作地学断面图提供了软件工具。建立了网页类型的中国地学断面元数据库,编撰了地学断面电子字典帮助文件。上述综合研究工作为中国地学断面图资源共享提供了底层数据和技术支撑。     

全球地学断面数字化图形数据库建设

以原地质矿产部系统所完成的6条地学断面图为源数据基础，选用MAPGIS软件平台对6条地学断面图进行了数字化，根据“全球地学断面数字化指南”，并参考了各地学断面的制图标准，建立了中国地学断面图形库和属性库。开发，研制了图形库管理系统。     

中国满洲里－绥芬河地学断面地球化学研究

中国满洲里－绥芬河地学断面地球化学研究李双林，迟效国，尹冰川，戚长谋（中国科学院地球化学研究所贵阳５５０００２）（长春地质学院．长春１３００６１）关键词地学断面，地球化学分区，地球计学分带，构造演化地学断面的地球化学研究的目的是为了查明断面域地壳一上...     

对地质矿产部GGT数字化工作的建议

1991年9月,国际GGT计划协调委员会在北京召开了“地学断面数字化国际讨论会”.来自北美、欧洲及中国等的GGT编者和计算机应用研究人员,制图人员,在会上交流和讨论了GGT数字化的方法和途径,展示了由数字化工作形式出版的GGT图件.现任GGT协调委员会主席戈策(H.J.G(?)tge)教授就如何推动GGT数字化工作,及今后地学断面的出版过程,谈了若干设想.此次会议上反映了数字化技术现状和90年代GGT研究的趋势.     

青藏高原亚东－格尔木地学断面地球物理综合解释模型与现今地球动力学过程

从实际资料出发，针对地学断面研究区域复杂的地学问题，运用人机交互解释系统，综合研究建立了表达断面结构构造的地球物理解释模型，追溯了岩石圈演化的地球动力学过程。     

The Geoscience Transect from Xiangshui,Jiangsu Province to Mandal,Inner Mongolia

The Xiangshui to Mandal geoscience transect, which has a total length of 1,200 km, extends diagonally,from SE to NW, across the Sino-Korean plate and its ancient continental margin, passing through nine tectonicunits: the Subei-Jiaonan terrane, West Shandong block, North China rift basin, Taihang-Wutai block, Ordosblock, Hu-Bao (Hohhot-Baotou) Basin, Yinshan block and Inner Mongolian fold system. The graphic display of the transect is compiled according to the Guidelines for the Global GeoscienceTransect (GGT) Project on the basis of an integrated study of all available geological, geochemical andgeophysical data, thus bringing light to the process of cratonization of the Sino-Korean plate and its relation-ship with the transitional zone of the ancient continental margin, and the features of intraplate structures pro-duced by subsequent tectonic modifications and intraplate dynamics.     

中国大陆地壳上地幔不均匀性与矿产资源预测

在充分收集、整理、综合研究中国大陆11条地学断面(简称GGT)、数十条其它地球物理剖面(地震剖面、大地热流、大地电磁测深等剖面)和覆盖中国大陆及邻区的剪切波三维速度结构资料的基础上,阐述了中国大陆及邻区地壳结构、岩石圈结构和软流圈结构,并对中国大陆矿产资源预测作了简单的讨论。中国岩石圈结构是在三种不同性质的软流圈基础上发展起来的,有明显的继承性。中国岩石圈结构在某种程度上与大地构造单元相吻合,说明地壳构造受到岩石圈的影响和制约。尤其在地震波垂向低速带上(地壳上地幔都表现为低速性质)是内生多金属矿带的良好产出环境。     

GPR studies over the tsunami affected Karaikal beach,Tamil Nadu,south India

In this study, results of GPR profiling related to mapping of subsurface sedimentary layers at tsunami affected Karaikal beach are presented . A 400 MHz antenna was used for profiling along 262 m stretch of transect from beach to backshore areas with penetration of about 2.0 m depth (50 ns two-way travel time). The velocity analysis was carried out to estimate the depth information along the GPR profile. Based on the significant changes in the reflection amplitude, three different zones are marked and the upper zone is noticed with less moisture compared to other two (saturated) zones. The water table is noticed to vary from 0.5 to 0.75 m depth (12–15 ns) as moving away from the coastline. Buried erosional surface is observed at 1.5 m depth (40–42 ns), which represents the limit up to which the extreme event acted upon. In other words, it is the depth to which the tsunami sediments have been piled up to about 1.5 m thickness. Three field test pits were made along the transect and sedimentary sequences were recorded. The sand layers, especially, heavy mineral layers, recorded in the test pits indicate a positive correlation with the amplitude and velocity changes in the GPR profile. Such interpretation seems to be difficult in the middle zone due to its water saturation condition. But it is fairly clear in the lower zone located just below the erosional surface where the strata is comparatively more compact. The inferences from the GPR profile thus provide a lucid insight to the subsurface sediment sequences of the tsunami sediments in the Karaikal beach.     

Detection of sinkholes using 2D electrical resistivity imaging in the Cheria Basin (north–east of Algeria)

Sinkhole collapse is one of the main limitations on the development of karst areas, especially where bedrock is covered by unconsolidated material. Studies of sinkhole formation have shown that sinkholes are likely to develop in cutter (enlarged joint) zones as a result of subterranean erosion by flowing groundwater. Electrical resistivity imaging or tomography (RESTOM) is well suited to mapping sinkholes because of the ability of the technique for detecting resistive features and discriminating subtle resistivity variations. Two-dimensional electrical resistivity tomography surveys were conducted at two sinkhole sites near Cheria city where limestone is covered by about 10 m of clayey soils. A Wenner transect was conducted between the two sinkholes. The electrode spacing was 2 m. The length of transect is about 80 m. The survey results suggest that RESTOM is an ideal geophysical tool to aid in the detection and monitoring of sinkholes and other subsurface cavities.     

Distribution of benthic flora in the lower course of the Valdivia River,Chile

The Valdivia River (Lake Region, Chile) originates in Riñihue Lake and flows into the sea at Corral Bay (39°52′S latitude), changing names several times along its course. The aquatic benthic flora (algae and aquatic plants) of the Valdivia River was characterized, based on 22 sites sampled and 124 plant species collected. Four benthic vegetation zones were established using presence-absence data: a freshwater zone and a marine zone were found at the extremes of the transect; an estuarine zone and a discontinuity zone were detected in the middle of this transect. The freshwater zone was characterized by a relatively diverse assemblage of vascular plants, the marine zone was dominated by algae and was rich in species. By contrast the estuarine zone was inhabited by only a few species but in great abundance, while the discontinuity zone was poor, in species and low in cover vegetation.     

Pressure–temperature–structural distance relationships within Greater Himalayan rocks in eastern Bhutan: implications for emplacement models

In the Himalayan orogen, Greater Himalayan (GH) rocks were buried to mid‐ to lower‐crustal levels and are now exposed across the strike of the orogen. Within the eastern Himalaya, in the Kingdom of Bhutan, the GH is divided into structurally lower (lower‐GH) and upper (upper‐GH) levels by the Kakhtang thrust (KT). Pressure–temperature estimates from lower‐ and upper‐GH rocks collected on two transects across the KT yield similar P–T–structural distance trends across each transect. In the eastern transect, temperatures are similar (from 730 to 650 °C) over a structural thickness of ~11 km, but peak pressures decrease from ~10 to 6 kbar with increasing structural level. In comparison, peak temperatures in the central Bhutan transect are similar (from 730 to 600 °C), but pressures decrease from 10 to 6.5 kbar with increasing structural level over a structural thickness of ~6 km. The structurally highest sample reveals slightly higher pressures of 8.0 kbar in comparison to pressures of ~6.5 kbar for samples collected from within the KT zone, ~4 km below. Within each transect, there are increases in pressure ± temperature within the overall upright P–T gradient that may demarcate intra‐GH shear zone(s). These P–T results combined with evidence that the timing of initial melt crystallization becomes older with increasing structural level suggest that the intra‐GH shear zones emplaced deeper GH rocks via progressive ductile underplating. These shear zones, including the KT, likely aided in the initial emplacement and construction of the GH as a composite tectonic unit during the Late Oligocene to Early Miocene, from c. 27 to 16 Ma.     

Late Cenozoic transpressional ductile deformation north of the Nazca–South America–Antarctica triple junction

The southern Andes plate boundary zone records a protracted history of bulk transpressional deformation during the Cenozoic, which has been causally related to either oblique subduction or ridge collision. However, few structural and chronological studies of regional deformation are available to support one hypothesis or the other. We address along- and across-strike variations in the nature and timing of plate boundary deformation to better understand the Cenozoic tectonics of the southern Andes.Two east–west structural transects were mapped at Puyuhuapi and Aysén, immediately north of the Nazca–South America–Antarctica triple junction. At Puyuhuapi (44°S), north–south striking, high-angle contractional and strike-slip ductile shear zones developed from plutons coexist with moderately dipping dextral-oblique shear zones in the wallrocks. In Aysén (45–46°), top to the southwest, oblique thrusting predominates to the west of the Cenozoic magmatic arc, whereas dextral strike-slip shear zones develop within it.New ⁴⁰Ar–³⁹Ar data from mylonites and undeformed rocks from the two transects suggest that dextral strike-slip, oblique-slip and contractional deformation occurred at nearly the same time but within different structural domains along and across the orogen. Similar ages were obtained on both high strain pelitic schists with dextral strike-slip kinematics (4.4±0.3 Ma, laser on muscovite–biotite aggregates, Aysén transect, 45°S) and on mylonitic plutonic rocks with contractional deformation (3.8±0.2 to 4.2±0.2 Ma, fine-grained, recrystallized biotite, Puyuhuapi transect). Oblique-slip, dextral reverse kinematics of uncertain age is documented at the Canal Costa shear zone (45°S) and at the Queulat shear zone at 44°S. Published dates for the undeformed protholiths suggest both shear zones are likely Late Miocene or Pliocene, coeval with contractional and strike-slip shear zones farther north. Coeval strike-slip, oblique-slip and contractional deformation on ductile shear zones of the southern Andes suggest different degrees of along- and across-strike deformation partitioning of bulk transpressional deformation.The long-term dextral transpressional regime appears to be driven by oblique subduction. The short-term deformation is in turn controlled by ridge collision from 6 Ma to present day. This is indicated by most deformation ages and by a southward increase in the contractional component of deformation. Oblique-slip to contractional shear zones at both western and eastern margins of the Miocene belt of the Patagonian batholith define a large-scale pop-up structure by which deeper levels of the crust have been differentially exhumed since the Pliocene at a rate in excess of 1.7 mm/year.     

跟踪国际前沿,开招研究领域——青藏高原“亚东—格尔木地学断面”介绍

<正> 岩石圈研究计划是继60年代国际上地幔计划和70年代国际地球动力学计划后,于80年代开展的一项大型国际合作研究项目,其全称是“岩石圈的动力学、组成和演化—自然资源和减轻灾害研究纲要”。国际岩石圈研究计划是一个跨地区、跨部门的多学科国际合作研究计划。它运用地质、地球物理和地球化学等多学科手段和方法,从三维空间研究岩石圈的结构、构造、动力学及其形成、演化过程,以满足人类对矿产资源和环境保护的需求,减轻地质灾害,并为板块构造理论发展作出贡献。岩石圈研究是一项大型地学基础性研究项目,是当前地球学科的前沿课题,也是各国致力研究的重大课题。     

Structures of the late palaeozoic thrust belt in the Chinese South Tian Shan

Aiming to resolve contradictions in tectonic models and to establish a correlation between Chinese and Kyrgyz sectors of the South Tian Shan we carried out stratigraphic and structural studies in Chinese part of the belt along the Bayinbuluk—Kuqa transect. New data indicate that Chinese South Tian Shan is dominated by top-to-the-south structures, which were formed during the latest Carboniferous and Early Permian. Major allochthons of the Devonian carbonates, thrusted on the Gzhelian and Asselian turbidites, are revealed in the northern part of the belt. Imbricated thrust packages and recumbent folds in deeper marine Devonian and Carboniferous rocks are common in the South. Postkinematic granites yield U-Pb ages of 285–275 Ma, which indicate that thrust deformation ceased by the middle of the Early Permian. The same direction of motion and similar age of deformations in Kyrgyz and Chinese sectors of the South Tian Shan prove, that top-to-the-south structures were formed during the same structural episode, which corresponds to the main collisional stage within entire belt.