【作者】 曹征；

【导师】 毛晓冬；

【作者基本信息】 成都理工大学 ， 矿物学、岩石学、矿床学， 2011， 硕士

【摘要】 本文在系统收集前人土门格拉煤田区域地质调查、煤田地质勘查资料的基础上,全面了解和分析了土门格拉煤田地质调查、勘查和研究现状,系统归纳了前人在该区开展煤田地质工作中存在的问题和不足,概括起来主要包括:(1)区域地质调查精度不够;(2)对土门格拉煤矿的普查和勘探范围太过局限,以至对整个煤田的评价不完整;(3)煤田内含煤地层系统划分及对比不统一;(4)主要控煤因素和控煤构造的调查和研究不足,以至对煤田内控煤构造样式了解不清;(5)未开展过煤田的沉积相、沉积环境及沉积盆地的系统研究,较缺乏含煤盆地类型及其形成演化的研究和全面认识;(6)聚煤规律认识不够,严重制约了对煤田内煤炭资源潜力的正确评价;鉴于此,为本次硕士论文研究提供了充分的选题依据。本次硕士论文研究,基本研究思路和技术路线十分明确,在充分吸收前人地质调查、煤田地质勘查和研究成果的基础上,系统研究了土门格拉煤田成煤的区域地质条件、含煤岩系、煤层及其分布特点,并结合青藏高原地质大调查以来最新1:25万区域地质调查成果资料和相关煤田地质研究专题,以聚煤盆地的大地构造演化、控制沉积盆地类型和沉积充填层序为主线,运用岩石地层、生物地层、年代地层及层序地层相结合的研究方法,通过对土门格拉煤田煤系典型沉积剖面结构和层序地层学特征的系统分析,对土门格拉煤田构造地质特征、煤系层序地层学、沉积相和沉积环境、沉积地球化学特点、煤岩学等方面进行了全面总结,在建立土门格拉煤田岩石地层格架基础上,恢复了土门格拉煤田晚三叠世构造-岩相古地理格局。在认真研究土门格拉煤田控煤因素,特别是控煤沉积环境及控煤构造样式基础上,以地表已揭露或控制煤层为依据,注重研究后期地质事件所诱发的主要构造活动对煤层的影响,剖析了该煤田的主要聚煤规律,重点考虑后期构造对煤系地层及煤层的改造和破坏作用,运用构造控煤理论,圈定了最小含煤远景预测区,并对预测区可靠程度、潜在资源量等级进行了划分,论文最后采用体积法对土门格拉煤田深部及外围的潜在资源量进行了估算。土门格拉煤田位于龙木错-双湖-类乌齐构造-地层大区,大地构造环境则隶属于班公湖-双湖-怒江构造缝合带的北部边缘带。论文在充分借鉴前人对土门格拉煤田地质调查、普查、勘探以及大量与之有关的构造地质作用、沉积作用、岩相古地理研究成果,以岩石地层的系统划分与对比为基础,结合煤系生物地层、年代地层特点,对土门格拉煤田地层及含煤岩系进行了较合理的划分和对比。土门格拉煤田煤系为上三叠统土门格拉组,根据岩性特点及其含煤性,可进一步划分为上下两段,即土门格拉组一段(T3tm1)、土门格拉组二段(T3tm2);煤田内出露其他地层主要为中-上侏罗统,少量下白垩统,从下向上依次包括:雀莫错组(J2q)、布曲组(J2b)、夏里组(J3x)、索瓦组(J3s)、白龙冰河组(J3b)、雪山组(J3 K1x)和阿布山组(K2a)。根据土门格拉煤田沉积剖面及钻孔资料,通过对晚三叠世南羌塘盆地沉积充填层序中沉积界面的识别和确认,对晚三叠纪土门格拉聚煤盆地不同演化阶段的岩相、古地理空间展布特征进行了系统的研究和分析,归纳了不同演化阶段的盆地充填沉积物特征;土门格拉组一段以碳酸盐岩沉积为主,二段主要为碎屑岩夹煤层和煤线沉积。通过对土门格拉组沉积层序的划分,发现土门煤系为一个发育完整的构造-沉积层序,通过关键沉积间断面的识别,可进一步划分出两个超层序和五个准层序。晚三叠世土门格拉聚煤盆地沉积相类型主要发育陆源碎屑三角洲相、碎屑潮坪相、泥炭沼泽相,三角洲相可区分出三角洲平原亚相、三角洲前缘亚相;其次还发育了碳酸盐开阔台地相;其中在碎屑潮坪相和三角洲平原亚相上发育起来的泥炭沼泽相是形成土门格拉煤田的聚煤沉积相,逐步形成了土门格拉煤田内71层煤层和煤线。从当前掌握的土门格拉煤田的煤层厚度、煤层稳定性及煤质煤种的情况上看,土门格拉煤田煤层普遍较薄;前人对羌塘盆地古地磁测定结果表明,土门格拉煤田成煤时的羌塘-昌都地块地处南半球,植被繁茂,虽然成煤环境有利,但成煤期整体沉积环境处于高水位体系域,决定了土门格拉煤田形成的煤层普遍较薄。通过探讨沉积盆地构造沉降-沉积充填-海平面变化和构造隆升-沉积间断-海平面变化之间的关系,结合构造-岩浆事件分析发现,晚三叠世羌塘-昌都地区整体处在拉张背景之下,北羌塘-昌都地块和南羌塘-保山地块都相继发生坳陷沉降,而以龙木错-双湖蛇绿混杂岩带所构成的中央隆起为剥蚀区,将羌塘盆地分割为南、北两个不同性质的沉积盆地。晚三叠世土门格拉煤田则地处南羌塘盆地北部的边缘,位于唐古拉山古隆起剥蚀区南侧(晚三叠世羌塘中央隆起带的一部分)的晚三叠世南羌塘大陆边缘残余盆地之中,经历了晚三叠世被动陆缘坳陷盆地的演化历程,早-中侏罗世古地理基本继承了这一格局。论文首次提出,晚三叠世诺利期形成的土门煤系,其聚煤盆地类型属于南羌塘残余盆地中有利于聚煤的被动陆缘坳陷盆地,成煤古地理格局十分稳定,极其有力于泥炭沼泽环境的发育,在土门格拉一带构成了良好的成煤环境,古气候由湿润逐渐向干旱环境演变。土门格拉煤田内煤系空间展布及煤层赋存状态主要受聚煤期后沉积作用、构造变形等因素的控制。土门格拉煤田经历了多期构造地质活动,具有构造变形强烈、构造形迹复杂的特点。本文首次探讨了聚煤期后各种构造形式对煤系的改造作用,如逆断层对煤层的影响,以及正断层、走滑断层、平移断层和褶皱构造对煤层的影响,为深入了解土门格拉煤田煤层的分布及赋存状态奠定了基础,进而为深部和外围煤层的预测提供了较可靠的地质依据。论文通过对煤系空间展布的系统了解和聚煤规律综合分析,结合后期构造对煤系及煤层的影响,运用构造控煤理论,圈定了最小含煤远景预测区,划分为三类:有利的(Ⅰ类)、次有利的(Ⅱ类)和不利的(Ⅲ类);又根据预测可靠程度,将潜在资源量分为三级:预测可靠的(334-1)、预测可能的(334-2)、预测推测的(334-3)。根据土门格拉预测区控煤构造及沉积特征,圈定出三个最小预测区,即北部预测区、中部预测区、南部预测区,以及10个预测段;最后依据体积法估算资源量,对各个预测段选择合理而符合资源勘查规范的预测参数,对潜在资源量进行了估算,土门格拉煤田预测总资源量为30811.83万吨。更多还原

【Abstract】 Geological Survey、prospecting and Current Situation in Tumengela Coalfield are analyzed and comprehended comprehensively on the basis of systematic collection of pre-existing regional geological survey and coal geological survey, with induction of problems and insufficient in the former coalfield geology, generalizing including:(1) accuracy of regional geological survey is insufficient; (2)survey and exploration is too limited, accordingly the valuation of the whole coal field is not completed, (3)division and correlation of coal bearing formation system in coalfield is not a final conclusion;(4)insufficient survey and study of the main coal-controlling factor and coal-controlling structure lead to ambiguous cognition on coal-controlling structure model;(5)study on sedimentary facies、sedimentary environment and sedimentation basin haven’t been developed, accordingly the coal-bearing basin type and formation-evolution are not explicit;(6)insufficient cognition of coal accumulating pattern heavily restrict the valuation to coal resources potential of the coal field. In consideration, the six provide the necessity of the Master’s thesis.With significant research approach and technical route, regional geological conditions、coal-bearing formation、coal bed and distribution features are well studied, referring to pre-existing geological survey、coal geological survey and other researches, combining with the latest Tibet Plateau 1:250000 scale regional geological survey and relevant coal geologic dissertation. This paper takes geotectonics evolution of coal-accumulating basin、controlling sedimentary basin types and depositional filling sequence as the main line, and applies lithostratigraphy、biostratigraphy、chronostratigraphy and sequence stratigraphy combining together. Though System Analysis of coal measures sedimentary profile structure and sequence stratigraphic characters, this paper comprehensively sums up the tectonic geologic feature、coal sequence stratigraphy、sedimentary facies and sedimentary environment、sedimentary geochemistry and coal petrography. After lithostratigraphic framework is built up, the late Triassic structure- lithofacies paleogeography structure. On the basis of serious research of coal-controlling factor of Tumengela Coalfield, especially coal-controlling sedimentary environment and coal-controlling structure model , taking surface exposed or controlled coal bed as the reason, it majorly discusses the influence of main tectonic activity which induced by later geological events, to coal bed, and dissects the main coal accumulation in this coal field, which mainly considers the transforming and destructive actions, the later tectonics to coal measure strata and coal bed. Applying tectonic coal-controlling theory, the minimum coal-bearing prospect prediction area is made, and makes division on the reliable degree of prediction area and potential resources grade, then the valuation applying volume method in deep Tumengela Coalfield and circumjacent potential resources.On the stratigraphic area , Tumengela Coalfield located on Longmucuo- Shuanghu-Leiwuqi structure formation zone, while according to the tectonic, it belong to the northen of Bangonghu- Shuanghu- Nujiang butt zone. This paper were based on the previous geological survey reports of Tumengela Coalfield and the many relation study results of structural geology,deposition and lithofacies palaeogeography. By the features of chronostratigraphy and biostratigraphy, and in association with systematic division and contrast of lithostratigraphic, stratum of Tumengela Coalfield was objectively divided and compared. Tumengela Coalfield was located in Tumengela group, which consists of first section of Tumengela group (T3tm1) and second section of Tumengela group(T3tm2) by lithologic features and coaled features, and in the coalfield, from the bottom up, the other exposed stratums followed as Quemocuo group (J2q), Buqu group (J2b), Xiali group (J3x) , Suowa group (J3s), Bailongbinghe group (J3b), Xueshan group (J3 K1x) and Abushan group (K2a).According to the materials of Tumengela Coalfield deposition profiles and drillings, by identification and validation to deposition interface of depositional sequence in South Qiangtang Basin Late Triassic, lithofacies and spatial distribution of ancient geography in different stages of evolution in Tumengela Coal Basin late Triassic were systematically studied and analyzed, and features of basin filled sediments in different stages of evolution were generalized. The first section of Tumengela group primarily belongs to carbonate rocks, while the second section of Tumengela group primarily is clastic coal and deposition of coal line. By dividing sedimentary sequence of Tumengela group, it was found that Tumen coal is an incompletely developed construction-sedimentary sequence. Thus, by identifying pivotal sedimentary discontinuity, it could divided complete construction-sedimentary sequences, which are incomplete two super-sequences and five sequences.In Late Triassic, sedimentary facies in Tumengela Coalfield accumulating basin mainly develops terrigenous clastic delta、clastic-tidal flat facies、peat-swamp facies,and delta faceies can divide to delta plain facies、delta front facies;then developing carbonate-open platform facies, among them, peat-swamp face from clastic-tidal flat facies and delta plain facies is coal-accumulating sedimentary facies, gradatim forming 71 coal bed and coal streak. According to the current materials including coal seam thickness、coal seam stability and coal quality and coal type in Tumengela Coalfield, coal bed in Tumengela Coalfield is generally thin; the Paleomagnetic Tests in Qiangtang basin indicates that Qiangtang-Changdu block when coal forms locates at the Southern Hemisphere, with flourish vegetation, which although is good for the coal-forming environment, the sedimentary environment locates at high water level system tract through the whole coal-forming course, determining that the coal bed in Tumengela Coalfield is generally thin.Though the interrelation discussion of tectonic subsidence- depositional filling-sea level change and tectonic uplift- depositional hiatus- sea-level change of sedimentation basin, combining with structure-magma event analysis, in late Triassic, Qiangtang-Changdu block entirely locate at pull apart environment, North qiangtang-Changdu block and South qiangtang-Baoshan block both occur depression sedimentation in succession , while the central massif formed by Longmucuo-Shuanghu ophiolite melange belt, divided the Qiangtang basin into southern and northern two different sedimentation basin. In late Triassic, Tumengela Coalfield locates at the edge of northern south Qiangtang basin,in the late Triassic South qiangtang marginal relict basin which locates at the southern Tanggula paleo uplift denudation area, and experience the late Triassic evolvement of passive continental margin depression basin, which early-middle Jurassic paleogeography inherit the structure. This is the first time to present that Tumen coal formed in norian the late Triassic, which coal accumulating basin type belong to coal accumulating beneficial passive continental margin depression basin in south Qiangtang relict basin, has a stable coal-forming paleogeography pattern, extremely good for development of peat swamps environment, composing a well coal-forming environment in Tumengela area , with paleoclimate evolving from moist to arid environment gradually. The coal spatial distribution and occurrence status in Tumengela Coalfield were mainly controlled by deposition after coal accumulation and construction deformation. After multistage tectonic activities, the feature of Tumengela Coalfield was strong and complex deformation. In this thesis, the reformed effects of every structural form to coal after coal accumulation were discussed, such as the effect of reverse faults, normal faults, strike-slip faults and folds to coal. That were basis to deeply understand the distribution and occurrence status in Tumengela Coalfield and to forecast the deeper and periphery coal.In the paper, according to system understanding of space exhibition of coal measures and comprehensive analysis of coal accumulating pattern, combining with influence of later structure to the coal measure strata and coal bed, applying structure-controlling theory, the minimum coal-bearing prospect prediction area is made and divided into three: favorable(Ⅰ)、secondary favorable(Ⅱ)and unfavorable(Ⅲ); then furtherly,refer to forecast reliability degree, the potential resource is divided into three: forecast reliability(334-1)、forecast probable(334-2)、forecast conjectural(334-3).According to coal-controlling structure and depositional features in forecast area of Tumengela, three minimum predicting areas are made, that is northern predicting area、centre predicting area and southern predicting area, and 10 forecast section; finally, using volume method to estimate resource extent, and choosing the reasonable and corresponding the specifications of resource exploration forecast parameters to estimate, the total resource extent is 308.1183 million tons.更多还原