Petrographic characteristics and depositional conditions of Permian coals of Pench, Kanhan, and Tawa Valley Coalfields of Satpura Basin, Madhya Pradesh, India     

Mahendra P. Singh  R.Rakesh Shukla 《International Journal of Coal Geology》2004,59(3-4):209-243

This paper attempts to characterize the coals of Satpura Gondwana basin using a large number of pillar coal samples drawn from the working coal mines of Pench, Kanhan, and Tawa (Pathakhera) Valley Coalfields of this basin. This westernmost Gondwana basin of Peninsular India is graben/half-graben type and occupies an area of 12 000 km² with sedimentary fills (>5000 m) ranging in age from Permian to Cretaceous. The Barakar Formation (Permian) is exclusively coal-bearing with a total coal reserve of nearly 2000 Mt. The results show that the coals of this basin are equally rich in inertinite (22.8–58.7%, 24.5–62.0% mmf basis) and vitrinite (24.4–52.4%, 24.4–56.0% mmf basis). The concentration of liptinite ranges from 8.8% to 23.2% (9.0–26.0% mmf basis). The dominant microlithotypes of these coals are inertite and vitrite with comparatively low concentrations of vitrinertite and clarite. The vitrinite reflectance (Rom% values) suggests that the Pench Valley (0.30–0.58%) coals are subbituminous C to high volatile C bituminous in rank, while the Kanhan and Tawa Valley coals (0.52–0.92%) are subbituminous A to high volatile A bituminous in rank. The localized enhancement of rank in the latter two basins has been attributed to the extraneous heat flow from deep-seated igneous intrusions in the basin. The microlithotype composition of these coals is suggestive of their evolution in limno-telmatic zones, under fluvio-lacustrine control with the development of upper deltaic and lower deltaic conditions near the fresh water lacustrines. The floral input is characteristic of forest swamps with intermittent floods, leading to the development of reed moor and open moor facies, particularly in the Pench Valley basin. The Gelification Index (GI) and Tissue Preservation Index (TPI) are suggestive of terrestrial origin with high tree density. Further, moderately high GI and exceedingly high telovitrinite based TPI along with high ash content, particularly for the coals of Kanhan and Tawa Valley Coalfields, are indicative of the recurrence of drier conditions in the forested swamps. Furthermore, lateral variation in TPI values is indicative of increase in the rate of subsidence vis-à-vis depth of the basin from east to west (Pench to Tawa Valley Coalfield). The Ground Water Index (GWI) suggests that these coals have evolved in mires under ombotrophic to mesotrophic hydrological conditions. The Vegetation Index (VI) values are indicative of the dominance of herbaceous plants in the formation of Pench Valley coals and comparatively better forest input in the formation of Kanhan and Tawa Valley coals.  相似文献   

内蒙古虎拉林地区砂金与岩金的关系     

王治华  刘荫椿  王科强  刘桂阁  张勇 《黄金地质》2004,10(1):6-10

虎拉林地区砂、岩金矿的空间位置关系十分密切。在虎拉林河上中下游及虎拉林岩金矿分别采取样品，结果表明虎拉林河砂金粒度大，分选较差，磨圆度差；砂金形态总体上以粒状为主；溶蚀系数均值小于1。微量元素含量特征表明砂金的主要物质来源是近源，与岩金矿关系密切且具有继承性。虎拉林岩金矿床的矿石中自然金颗粒粗大，矿体的上部遭到剥蚀，虎拉林河砂金主要来源于虎拉林岩金矿床，砂金可作为岩金的找矿标志。自然金化学-结晶温度图表明砂金的原生Au源为中低温热液矿床。  相似文献   

Microorganisms Linked to Neoproterozoic Microspar Carbonate Sedimentation in the Jilin-Liaoning Area   总被引：2，自引：1，他引：2  

GE Ming  KUANG Hongwei  MENG Xianghua  George FURNISS Institute of Sedimentary Basin  China University of Geoscience  Xueyuan Ro  Beijing  China Yangzi University  Nanjing  Jiangsu  China Geology Department  University of Montan  Missoul  Montan  USA 《《地质学报》英文版》2004,78(3):784-789

Molar-tooth carbonate refers to a sort of rock that has ptygmatical folded structure comparable to the ivory. This kind of carbonate exists in a special time range (from Middle to Neoproterozoic). Its origin and the possibility to use it in stratigraphic correlation of the paleocontinent is the key task of the IGCP447, a project on Proterozoic molar tooth carbonates and the evolution of the earth (2001-2005). The importance lies in that the molar-tooth structure is the key to solving problems related to Precambrian biological and global geochemical events. The molar-tooth structure is associated with microorganisms. Development and recession of such carbonates have relations with the evolution process of early lives and abrupt changes in sea carbonate geochemistry. In recent years, based on researches on petrology, geochemistry and Sr isotope of molar-tooth carbonate in the Jilin-Liaoning and Xuzhou-Huaiyang area, the authors hold that it can be used as a marker for stratigraphic sequence and sedimentary  相似文献   

西秦岭糜署岭岩浆带成因及构造意义   总被引：6，自引：0，他引：6  

李永军  谢其山  栾新东  李注苍  杨俊泉  毕明波 《新疆地质》2004,22(4):374-377

糜暑岭岩浆带分布于西秦岭黄渚关EW向深大断裂带中，由2类岩石组成，酸性端元以草关、董河岩体为代表，岩性为中粗粒似斑状石英闪长岩-辉长闪长岩组合；基性端元以挖泉山岩体为代表，岩性为细粒辉长岩，而糜暑岭、黄渚关岩体则是2类岩浆的强烈混合产物，不仅大量的岩石学资料佐证了岩浆混合作用的存在，而且主岩与其混合作用形成的包体具有一致的同位素年龄，主岩中钾长石中的Pb同位素具有明显的幔源性质，因而是一个与幔源岩浆作用有关的构造岩浆带，这为确定区域性构造边界和大地构造单元划分提供了重要证据。同时，也为探讨本区中生代壳幔混合作用和地壳增生提供了新的信息。  相似文献   

New observations on the geomorphology and origins of Mountain Lake,Virginia     

Jon C. Cawley  Bruce C. Parker  Lee J. Perren 《地球表面变化过程与地形》2001,26(4):429-440

Mountain Lake is the only natural lake of significance in the unglaciated southern Appalachian Highlands. It is located near the summit of Salt Pond Mountain, Giles County Virginia, at an elevation of 1177 m. It is underlain by Ordovician and Silurian non‐calcareous shale and sandstone of the Martinsburg, Juniata and Clinch formations. Historical (250 years) and sediment (6000 years) records suggest that the size of the lake has varied periodically. In the 1930s lake origin was proposed as due to valley damming by a lateral landslide (Hutchinson and Pickford, 1932) or damming by scree (Sharp, 1933). A later theory modified the landslide hypothesis to the primarily vertical collapse of a canyon feature in the Clinch (Parker et al., 1975). Fracture trace analysis now reveals a regional lineation feature associated with the lake. This feature is present surficially both downgradient from the lake to the northwest, and upgradient to the southeast. Sonar bathymetry and diver reconnaissance show it expressed as a (relatively sediment‐free) narrow open crevice in the deepest (33 m) portion of the lake, probably a fault. Hydrologic observation and resistivity suggest preferential water movement along this fracture, as well as leakage directly from the lake. The present study suggests conduit erosion within this feature and periodic vertical downsettling of overlying Clinch material as the primary mechanism of lake origin and water‐level fluctuations through time. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

深源成矿论在松辽盆地南部可地浸砂岩型铀矿找矿选区中的应用     

赵忠华  李国宽 《铀矿地质》2001,17(6):328-331

深源成矿论是可地浸砂岩型铀矿地质找矿的一种新思路，在松辽盆地南部铀矿勘查中得到了较好的应用，其基本的预测准则为构造准则，岩性准则和地球化学准则。本文总结并提出了铀成矿评价的3个必要条件：透水疏松砂岩层，富铀物源补给区及地球化学栅。1：200000带钻区调已在该区找到有利的成矿环境和成矿远景区。  相似文献   

大别超高压碰撞造山带岩石锆石U/Pb同位素框架年代学   总被引：7，自引：0，他引：7  

陈道公  李彬贤  夏群科  吴元保  程昊 《矿物岩石地球化学通报》2001,20(4):253-255

采用SIMS和TIMS法对大别造山带各主要构造地体 (南大别、北大别、北淮阳和苏鲁 )中的片麻岩和榴辉岩中锆石进行了U Pb定年 ,得到的年龄主要分布在 12 0～ 140Ma,190～ 2 5 0Ma ,6 5 0～ 85 0Ma ,～ 190 0Ma和～ 2 5 0 0Ma。第一组年龄主要和侏罗纪—白垩纪的岩浆构造活动有关 ,第二组年龄和超高压变质作用有关 ,第三至第五组年龄则主要反映了变质岩原岩的年龄。根据锆石中的Th U讨论了各种锆石年龄的成因及其意义。  相似文献   

地下水中镁的形成及其与人群健康的关系   总被引：1，自引：0，他引：1  

曾昭华  曾雪萍 《四川地质学报》2001,21(3):168-170

利用国家科技攻关的成果，并根据国内外的研究现状，论证了地下水中镁元素的形成及其与人群健康的关系。  相似文献   

中国古地图起源探讨   总被引：2，自引：0，他引：2  

卢良志 《测绘学院学报》2002,19(3):227-229

关于中国地图如何起源的问题，在中国地图史研究的论文中还不多见，有关地图史的书籍中也很少论述，所以中国古地图起源问题已成为地图学史界一个悬而未决的问题。作者认为，原始社会已出现了描述自然现象的图画，而这些图画先于象形文字出现，尽管也有描述自然景物的图画，但还不是真正意义上的地图，只能算作地物画。夏末商初象形文字出现后，产生于原始社会的地物画与象形文字还没有明显的差别，于是形成了地物画与象形文字融为一体的地图发展阶段。周灭商后，由于生产和征战的需要，具有明显主题思想和实际使用价值的地图大量出现。  相似文献   

焉耆盆地侏罗纪含煤地层深水成因证据与沉积模式   总被引：1，自引：0，他引：1  

吴明荣  姜在兴  鲁洪波  蒲晓强 《新疆地质》2002,20(1):53-57

新疆焉耆盆地沉积环境研究表明，该盆地侏罗纪煤系具有两种不同的成因环境：即浅水原地环境和深水异地环境，从煤层的产状，与煤共生的泥岩中的有机质类型，与煤共生的碎屑岩的成分，结构，构造和相序等方面论述了焉耆盆地中生界含煤地层深水成因的证据，并建立了深水煤系沉积模式。  相似文献