淮北闸河矿区二叠系煤层特征的研究     

吴文金  刘文中 《城市地质》2000,12(2):27-31

通过研究区煤层的厚度、分布、煤岩及煤质等特征的研究,分析总结了淮北闸河矿区二叠系主采煤层的赋存规律。并结合该区二叠纪时沉积环境的演化历史,对煤层的形成过程进行了一定的分析与探讨。  相似文献   

Inter-taxa differences in extinction process of Maokouan (Middle Permian) fusulinaceans   总被引：1，自引：1，他引：0  

YANG Xiangning  SHI Guijun  LIU Jiarun  CHEN Yuntang  ZHOU Jianping 《中国科学D辑(英文版)》2000,43(6):633-637

Analyses of the extinction process of fusulinacean in the Maokouan (Middle Permian) biotic crisis have revealed remarkable differences between taxa with various morphological features. Nankinellinids suffered a heavy loss of species in the early stage of the Maokouan event. Schwagerinids and neoschwagerinids both showed a stepwise decrease in species diversity, but the pulses of species extinction occurred in different stages of the extinction process. The species extinction of verbeekinids happened primarily in the Late Maokouan.  相似文献   

Early period of early Permian tubular cyanobacteria reef in the eastern part of south Qinling Mountains   总被引：1，自引：0，他引：1  

GONG Enpu  FAN Jiasong 《中国科学D辑(英文版)》2000,43(4):347-355

A typical reef occurs in the eastern part of south Qinling Mountains in Sanlixia, Xunyang, Shaanxi Province. The reef, extending in north-south direction, was built up by various kinds of calcareous tubes including Girvanella, tubular cyanobacteria and problem microbials. The bioclastic bank, built up by algal clasts, foraminiferous, and fusulinids, formed the reef basement, on which dasyclads baffle bioclasts formed the original bafflestone at a small scale on the reef basement, and then a mass of bindstone was made up by all kinds of calcareous tubes and algae. On lateral part the reef is cryptalgal mudstone. The reef that occurred in the geosynclinal area is so familiar with one of the platforms in many respects, such as in reef structure, morphology and building mold. This indicates that building organisms have amazing adaptability and identity for building capacity in the two kinds of geotectonic background mentioned above.  相似文献   

Lithostratigraphy of Permian marine sequences, Khao Pun Area, central Thailand: Paleoenvironments and tectonic history     

Vichai Chutakositkanon  Punya Charusiri and  Katsuo Sashida 《Island Arc》2000,9(2):173-187

Geologic mapping and subsurface lithostratigraphic investigations were carried out in the Khao Pun area (4 km²), central Thailand. More than 250 hand specimens, 70 rock slabs, and 70 thin sections were studied in conjunction with geochemical data in order to elucidate paleoenvironments and tectonic setting of the Permian marine sedimentary sequences. This sedimentary succession (2485 m thick) was re‐accessed and re‐grouped into three lithostratigraphic units, namely, in ascending order, the Phu Phe, Khao Sung and Khao Pun Formations. The Lower to lower Upper Permian sedimentary facies indicated the transgressive/regressive succession of shelf sea/platform environment to pelagic or abyssal environment below the carbonate compensation depth. The sedimentological and paleontological aspects, together with petrochemical and lithological points of view, reveal that the oldest unit might indicate an Early Permian sheltered shallow or lagoonal environment. Then the depositional basin became deeper, as suggested by the prolonged occurrence of bedded chert‐limestone intercalation with the local exposure of shallower carbonate build‐up. Following this, the depositional environment changed to pelagic deposition, as indicated by laminated radiolarian (e.g. Follicucullus sp.) cherts. This cryptic evidence might indicate the abyssal environment during middle Middle to early Late Permian; whereas, previous studies advocated shelf‐facies environments. Following this, the depositional condition might be a major regression on the microcontinent close to Indochina, from the minor transgressive/regressive cycles that developed within a skeletal barrier, and through the lagoon with limited circulational and anaerobic conditions, on to the tidal flat to the sheltered lagoon without effective land‐derived sediments.  相似文献   

特殊碳同位素组成白云岩的发现及其意义   总被引：10，自引：2，他引：8  

张晓宝  徐永昌  王志勇 《沉积学报》2000,18(3):449-452

据现有文献报导,除前寒武系和第三系外,地史时期中白云岩δ13C值主要分布在-5‰～+5‰的范围。但是,作者在研究准噶尔盆地上二叠统芦草沟组白云岩碳同位素时获得了一批高度富集13C的资料,其中白云岩δ13C分布于7.3‰～ 17.9‰,平均11.7‰(7);白云石δ13C介于7.9‰～16,平均11.6‰(5)。根据区域地质、岩石学和矿物学资料,结合现代沉积剖面、细菌作用模拟实验和古代沉积剖面碳酸盐矿物碳同位素特征,分析了白云岩分布特征。作者认为白云岩中如此高的富集除了全球二叠纪生物埋藏速率较快和研究区古盐度较高外,更主要的因素应与厌氧条件下发酵带内细菌作用引起有机物质碳同位素分馏,形成贫的和富的有关。这一过程进行得愈充分,沉积介质中富集的的浓度越高,形成的白云岩碳同位素组成越重。同时,只有这一作用持续存在才能形成大量富的与黑色页岩互层的白云岩。这一现象从一个侧面说明在芦草沟组沉积时有一个持续时间较长的细菌活动时期,从而,生成了数量可观的以甲烷为主的生物气。由于生物气形成时代较老,易于扩散逸失,它们难于单独成藏保存至今,但作为天然气复合成藏来源之一,则应予关注。  相似文献   

进化序列系统学——以二叠纪瓦岗珊瑚类为例   总被引：1，自引：0，他引：1       下载免费PDF全文

徐桂荣  龚淑云 《地球科学》2000,25(1):1-10

进化序列系统学是古生物学中研究物种间和类别间的系统发育关系为目的的学科, 包括研究物种或类别间的亲缘关系, 并确定它们形成的先后序列.表型-分支系统学是该系统学的基础.分支系统学的许多重要概念在该系统学中加入了时间的含义, 例如, 认为最亲近的姐妹种之间的时间间隔不会超过它们母种的生存期.姐妹群和性状镶嵌分析是进化序列研究的主要方法, 而理解性状镶嵌分布是关键.这些分析可由计算机程序实现.以二叠纪瓦岗珊瑚类作为研究进化序列系统学的实例, 该类在特提斯地区广泛分布.通过对瓦岗珊瑚类的特征分析确定了17个性状用于研究, 并且每一性状确定了几个变化状态.根据最广布的性状状态、化石记录和个体发生等原则分辨出近祖性状状态, 并根据性状在系统发育中的重要性确定性状分级.然后, 确定了姐妹群间的关系和物种间的进化序列.在姐妹群与进化序列分析相互检验中可发现性状退化、平行演化和多向分支等古生物学重要现象, 并分辨出物种的异常顺序.在检验生物地层学首次出现事件讨论中推测了一些化石首次出现的可能层位.   相似文献   

Flow pattern within a Permian submarine slump recorded by oblique folds and deformed fossils, Ulladulla, south-eastern Australia     

John V. Smith 《Sedimentology》2000,47(2):357-366

The flow pattern within a slump in Permian marine rocks of the southern Sydney Basin, Australia, is recorded by folds and deformed fossils. Abundant brachiopod and bryzoan fossils in the slumped rocks are relatively undeformed, but fossil crinoid stems have been deformed by relative rotation of individual ossicles. Measurement of the strain indicates that the deformation of the crinoids is consistent with flexural flow folding within the slump. Previous models assume that curved slump fold axes remain parallel to the enveloping bedding surface of a slump sheet. Detailed measurements of the orientation of slump folds in this study found fold axes to be oblique to bedding, which is interpreted as a result of folds plunging downward towards the flanks of the slump or slump lobes. In the present model, fold axes are not generally parallel to the strike of the fold axial surface, and this can explain differences between the orientations of slump fold axes and axial surfaces when these are used as directional indicators of slump movement.  相似文献   

来宾县二叠纪菊花石研究     

张刚生  李家珍 《南方国土资源》1999,12(2)

来宾县菊花石围岩的主要成分为ＣａＯ、ＣＯ２、ＳｉＯ２和ＭｇＯ,总量达９５．９１％,微量元素Ｓｒ明显富集,平均值大于１０００×１０－６。Ｘ－射线衍射分析和Ｘ－射线能谱仪分析表明,来宾菊花石的原生矿物为菱锶矿。因此来宾菊花石不同于湖南浏阳菊花石,是一种新的菊花石类型。  相似文献   

淮北煤田二叠纪煤中稀土元素地球化学研究   总被引：9，自引：0，他引：9  

郑刘根  刘桂建  张浩原  高连芬  薛翦  Chou Chen-lin 《高校地质学报》2006,12(1):41-52

从淮北煤田二叠系10,7,5,4和3煤层中采集34个样品,采用等离子体质谱（ICP-MS）、中子活化（INNA）、等离子体发射光谱（ICP-AES）等方法对样品中主量元素和稀土元素进行了测试,利用X射线衍射等方法对煤中矿物质及其煤质参数进行了测定。在各种测试的基础上,全面分析了稀土元素含量特征、空间分布规律、地球化学参数和分布模式,探讨了淮北煤田二叠纪煤中稀土元素的主要来源及其在煤中的主要赋存方式。研究表明：与华北和国内外其他地区相比,本区煤层中稀土元素相对富集;产于石盒子组煤中的稀土元素含量高于山两组的,在同一煤层中自下而下稀土元素含量有增高趋势,在顶底板中可能出现富集。Ce呈正异常,Eu明显负异常,不同煤层稀土元素的分布模式相似,稀土元素和灰分具有较好的正相关,∑REE与灰分、灰分中的主要元素以及典型陆源灰分中的微量元素正相关,与反映海相的低灰组分相关性较差。结合煤中矿物质的X射线衍射结果,分析获知,淮北煤田二叠纪成煤环境基本不受海水影响,稀土元素主要由陆源供给,而且主要赋存在以高岭石、伊利石为主的粘土矿物中。  相似文献   

A note on fructification of Plagiozamites Zeiller （Noeggerathiales） based on association     

Jun WANG 《东北亚地学研究》2008,11(3):115-124

The fructification of the noeggerathialean foliage Plagiozamites is very likely a cylindric strobilus based on close associations from the Early Permian Lower Shihhotse Formation of Weibei Coalfield in Shaanxi and Dengfeng Coalfield in Henan. The strobilus is articulated. Sporophylls arise from the node, with the proximal parts slightly united and with a tight angle to the axis; distal parts upturned pointing upwards and nearly parallel to the axis, coveting the neighboring sporophylls of the next node. A sessile sporangium is situated at the adaxial side of each sporophyll. There are 12-16 sporangia and sporophylls in each node. This type of strobilus may have been identified as some sphenophyllalean/equisetalean cones in previous study.  相似文献