Paleoecology of Oligocarpia gothanii Halle from the Middle Permian of Southeastern Shanxi, North China

Fossil ferns are abundant and diverse in the Permian Cathaysian Flora of Shanxi, North China. Although plants assemblages of the Carboniferous and Permian have been extensively investigated, their palaeoecology and especially the paleoecology of ferns has not been studied in detail. Recent reinvestigation of Oligocarpia gothanii has revealed its growth habit and cloning reproduction strategy, but most previous studies lack integrated sedimentological and taphonomic data. In this study, new materials of O. gothanii have been collected from a floodplain setting in the middle Permian Lower Shihhotse Formation of southeastern Shanxi. These plant fossils were found in a lenticular claystone associated with rooting structures. They are characterized by aphlebia at the base of the penultimate rachis. Sedimentological, taphonomic and morphological analyses were conducted to understand the growth habit and ecology of the fern. The result indicates that the Oligocarpia gothanii had a prostrate, ground cover growth habit, and was dominant in pioneer floras that colonized disturbed floodplains.     

山东唐口二叠纪孢粉组合特征

通过对唐口二叠纪孢粉组合的分析研究,建立了该区二叠纪3个孢粉组合带,①Densosporites（套环孢）-Crassispora（厚环孢）组合;②Gulisporites（匙唇三缝孢）-Sinulatisporites（曲环三缝孢）组合;③Anticapipollis（逆沟粉）-Macrotorispora（大一头沉孢）组合。这3个组合带分别反映太原组、山西组、下石盒子组及上石盒子组的孢粉组合面貌,其地质时代分属于早二叠世、中二叠世,晚二叠世早期。     

鄂尔多斯盆地东南缘下二叠统沉积相

近几年的勘探开发发现,鄂尔多斯盆地东南缘下二叠统具有巨大的非常规天然气资源潜力。为探明其沉积环境,在详细的岩心、测井及室内分析化验的基础上,运用沉积学理论,对鄂尔多斯盆地东南缘下二叠统沉积相进行研究。研究结果表明:太原组发育障壁岛、泻湖、潮坪、浅海陆棚沉积,山西组发育三角洲、湖泊沉积;自太原组至山西组沉积环境经历了由海陆过渡相至陆相的演化过程。     

华北太原组镜质组中的超微类脂体及其煤性质异常原因

利用超薄切片透射电镜分析技术，对华北太原组和山西组煤中镜质组的超微结构和组分进行了分析，确认太原组镜质组中含有较丰富的超微类脂体，且超微类脂体主要来自菌藻类，山西组和太原组镜质组中超微类脂体数量存在明显差异。证实镜质体中超微类脂体数量和其化学性质紧密相关。从超微组分层次解释了山西组和太原组镜质组性质差异的原因，并分析讨论了太原组煤性质异常性的原因和煤还原程度问题，提出成煤过程中明显菌藻类低等生物贡献是太原组煤性质异常的一个重要原因。     

吉林延边地区汪清县大兴沟早二叠世华夏植物群的发现及其地质意义

吉林省延边地区汪清县大兴沟镇和盛村附近和盛组中首次采获大童植物化石:Lepidophylloides sp.,Stigmaria ficoides(Stemb.)Brongn.,Trizygia oblongifolium(Germ.et Kaulf.)Asama,Cal-amites cistii Brongn.,C...     

Palynological assemblages of non-marine rocks at the Permian–Triassic boundary, western Guizhou and eastern Yunnan, South China

Marine and non-marine facies of the Permian–Triassic boundary stratigraphic set (PTBST) are well developed in South China. Palynological assemblages enable subdivision and correlation of the Permian–Triassic boundary (PTB) rocks. Three palynological assemblages are recognized across the PTBST in two terrestrial PTB sections in western Guizhou and eastern Yunnan, South China. Assemblage 1 (Xuanwei Formation) is a Late Permian palynological assemblage dominated by ferns and pteridosperms, with minor gymnosperms. Most taxa are typical long-ranging Paleozoic forms, but the appearance of Lueckisporites confirms a Late Permian age for this assemblage. Assemblage 2 (PTBST) is marked by an abrupt decrease in palynomorph abundance and diversity, and thriving fungal/algal(?) spores. Assemblage 2 is still dominated by ferns and pteridosperms, with a few gymnosperms, but is characterized by a mixed palynoflora containing both Late Permian and Early Triassic elements. Most taxa are typical Late Permian ones also found in Assemblage 1, however, some taxa of Early Triassic aspect, e.g. Lundbladispora and Taeniaesporites, appeared for the first time. In Assemblage 3 (top Xuanwei Formation and Kayitou Formation), the proportion of gymnosperm pollen increases rapidly, exceeding that of ferns and pteridosperms, but the abundance of palynomorphs is still low. Typical Early Triassic taxa (such as Lundbladispora, Aratrisporites and Taeniaesporites) are present in greater abundance and confirms an Early Triassic age for this assemblage.     

苏里格地区山西组烃源岩地化特征及生烃能力评价

鄂尔多斯盆地苏里格地区上古生界地层为海陆交互及河流-湖泊三角洲相的石炭-二叠系含煤岩系。下二叠统山西组发育煤和暗色泥岩二类烃源岩。根据苏里格及周边地区大量钻井岩芯样品的残余有机碳含量,干酪根同位素,有机质显微组份组成,干酪根镜质体反射率（Ro）等地球化学数据,综合分析了下二叠统山西组烃源岩的有机质丰度,类型和热演化程度。采用有机碳产烃率法,分别计算了煤层和暗色泥岩的生烃强度。在此基础上,结合苏里格地区山西组成藏特征,综合评价认为山西组生烃能力居于中等偏低的级别。     

豫西济源二叠纪末-三叠纪初陆相微生物成因构造及其古环境意义

在豫西济源地区发现的陆相微生物成因构造（Microbially Induced Sedimentary Structures,MISSs）,主要发育在孙家沟组和刘家沟组,可分为2大类即微生物席生长构造和微生物席破坏构造,8小类即生长脊构造、瘤状突起、曲形脱水裂痕、纺锤状脱水裂痕、似正弦状构造、树枝状脱水裂痕、多边形脱水裂痕和直脊状脱水裂痕。镜下分析显示具有大"U"形脊、定向排列的石英颗粒、近平行的暗色黏土矿物条带及悬浮排列的云母颗粒等微生物成因特征。通过与鲁山、黎城中元古界以及宜阳、柳林早三叠系微生物成因构造对比研究,认为研究区的微生物成因构造具有较为特殊的埋藏学特征,受二叠纪末灾变事件、适宜的沉积条件和气候因素控制,代表着研究区以微生物群落为主、后生动物稀少、植被贫乏、气候炎热和水土流失严重等特征的一种陆相灾后生态系。     

临清坳陷晚古生代沉积环境及演化分析

该文分析了临清坳陷晚古生代沉积体系及沉积相,通过连井剖面沉积相的对比研究总结出其纵向演化特征。研究结果表明：临清坳陷晚古生代主要发育了台地-泻湖沉积体系、障壁-泻湖-潮坪沉积体系、潮坪沉积体系、河控浅水三角洲沉积体系以及河流-湖泊复合沉积体系。研究区沉积演化在纵向上表现清晰,其中晚石炭世—早二叠世的本溪、太原期主要发育海相沉积;二叠纪山西期主要为过渡相沉积;二叠纪上、下石盒子期主要为陆相沉积。     

Geochemical and Geological Characterization of Marine-Continental Transitional Shale: A Case Study in the Ordos Basin, NW China

The organic-rich shale of the Shanxi and Taiyuan Formation of the Lower Permian deposited in a marine-continental transitional environment are well developed in the Ordos Basin, NW China, which is considered to contain a large amount of shale hydrocarbon resources. This study takes the Lower Permian Shanxi and Taiyuan shale collected from well SL# in the Ordos Basin, NW China as an example to characterize the transitional shale reservoir. Based on organic geochemistry data, X-ray diffraction (XRD) analysis, field-emission scanning electron microscopy (FE-SEM) observations, the desorbed gas contents of this transitional shale were systematically studied and the shale gas potential was investigated. The results indicate that the Lower Permian Shanxi and Taiyuan shale has a relatively high total organic carbon (TOC) (average TOC of 4.9%) and contains type III kerogen with a high mature to over mature status. XRD analyses show that an important characteristic of the shale is that clay and brittle minerals of detrital origin comprise the major mineral composition of the marine-continental transitional shale samples, while the percentages of carbonate minerals, pyrite and siderite are relatively small. FE-SEM observations reveal that the mineral matrix pores are the most abundant in the Lower Permian shale samples, while organic matter (OM) pores are rarely developed. Experimental analysis suggests that the mineral compositions mainly govern the macropore development in the marine-continental transitional shale, and mineral matrix pores and microfractures are considered to provide space for gas storage and migration. In addition, the desorption experiments demonstrated that the marine-continental transitional shale in the Ordos Basin has a significantly potential for shale gas exploration, ranging from 0.53 to 2.86 m3/t with an average value of 1.25m3/t, which is in close proximity to those of terrestrial shale (1.29 m3/t) and marine shale (1.28 m3/t). In summary, these results demonstrated that the Lower Permian marine-continental transitional shale in the Ordos Basin has a significantly potential for shale gas exploration.     

鄂尔多斯盆地西北部二叠系山西组古地理特征

本文以高分辨率层序地层学为理论基础,将山西组划分为6个中期旋回层序,并以此为编图单元编制了相应的砂体等厚图、地层等厚图及砂地比等值线图。基于基准面和可容空间的变化,分析了研究区古地理演化特征。研究表明,山32期至山12期,沉积作用以进积-加积为主,发育较大规模三角洲,沉积砂体较厚;山31期至山11期,沉积作用以进积-加积-退积为主,湖岸线向北推进,湖泊具有扩大的趋势;山2期三角洲平原规模较三角洲前缘大,山1期三角洲前缘有缩小的趋势。     

Diversity of the Woody Vegetation of Gondwanan Southern Africa

The flora of Gondwanan southern Africa is represented in the rock record by micro-fossils, macro-fossils and petrified woods. All these types of fossils are seldom preserved together in any one particular facies because of taphonomic and preservational biases. In order to obtain as accurate a picture as possible of the woody vegetation, both the fossil woods and other macroplant fossils, such as leaf impressions, fructifications and cuticle, of woody plants, have been correlated. This was done for each Formation in the Karoo Supergroup in order to illustrate the changes in diversity of woody vegetation over time. Sediments of the Karoo Supergroup represent the terrestrial fossil record of the period Upper Carboniferous to the Lower Cretaceous when Africa finally separated from South America. In the Upper Carboniferous to Lower Permian (Dwyka Formation) there are at least five described genera of woods from South Africa and Namibia. Early to Middle Permian woods (Ecca Group) are a little more diverse with six genera, representing the glossopterids, cordaitaleans and possibly other seed fern groups. Late Permian to Early Triassic (Beaufort Group) woods show very little change in diversity in spite of the major floral and biotic turnover evident from the rest of the fossil record. Although the Late Triassic (Molteno Formation) macro-flora has been shown to be an example of explosive diversification, the generally poorly preserved woods do not reflect this. Lower Jurassic fossils (Clarens Formation) are also poorly preserved but have araucarian characteristics. Early Cretaceous woods represent the Araucariaceae, Cheirolepidiaceae and Podocarpaceae with a number of species. The diversity of the woods has not changed as much as the rest of the floral components in southern Africa from the Late Carboniferous to the Early Cretaceous. Possible reasons for this apparent stasis are the conservative nature of wood, functional restrictions, limitations of suitable conditions for petrifications and the fact that very little research has been done on southern African woods.     

Oil-source correlation of the pre-Tertiary in the Huanghua Depression： Insights from stable carbon isotopes and molecular markers

Stable carbon isotopes were used together with molecular markers to constrain genetic relationships between sandstone extracts and potential source rocks in the pre-Tertiary in the Huanghua Depression, North China. Comparison of the extracts from Permo-Carboniferous terrigenous mudstones and Ordovician marine carbonates indicated that their prominent differences are in stable carbon isotopes, molecular markers and thermal maturity. Although the extracts of the Mesozoic and Lower Permian Xiashihezi Formation sandstones have some similar iso-topic characteristics, molecular markers data provide a good correlation between the Upper Jurassic-Lower Cretaceous oils and the Upper Carboniferous Taiyuan Formation mudstones, and between the Lower Permian Xiashihezi Formation oils and the Lower Permian mudstones. The results showed that the Upper Jurassic-Lower Cretaceous sandstone oils were derived chiefly from the Upper Carboniferous Taiyuan Formation terrigenous mudstones and that the Lower Permian Xiashihezi Formation oils were sourced from the Lower Permian Shanxi Formation and Xiashihezi Formation terrigenous mudstones.     

鄂尔多斯盆地西缘二叠系事件地层及其地球化学特征

通过钻井岩心的观察及镜下岩矿鉴定,同时依据地球化学和沉积学特征,把区内发育的事件地层分为两类:火山事件层和海退事件层,其中太原组火山事件层和海退事件层各1层,山西组火山事件层1层,石盒子组火山事件层3层。所体现的常量、微量和稀土元素质量分数及岩石学特征具明显的差异。研究事件地层获得的成果,可以为区域地层划分和对比提供更加准确的依据。      

鄂尔多斯盆地西缘断褶带南部二叠系山西组沉积特征及煤炭资源勘查潜力

研究区位于鄂尔多斯盆地西缘断褶带南部的平凉市安国-峡门-小湾子一带。通过对该区二叠系山西组沉积特征研究,对赋煤地质条件和煤炭资源勘查前景进行了评价。本区二叠系山西组含煤沉积、成煤条件受古隆起及其决定的古地理环境的影响,沉积物源供给区主要为研究区南部,沉积环境为曲流河及三角洲,沉积期后构造作用导致了已沉积地层的剥蚀、变形等,致使二叠系山西组煤层在研究区分布面积小、结构复杂、稳定性差、原煤灰分高。本区山西组含煤地层由于受多种因素的影响和控制,区内未能形成并保留规模较大的煤田,找煤工作应选在安国-峡门-小湾子向斜及周边进行。      

新疆南部早二叠世美羊齿类的发现

保存良好的Autunia conferta.和Dichophyllum flabellifera近来在新疆塔里木盆地西北缘下二叠统上部的发现,是在塔里木盆地的首次记录.这两个种以前曾被归于Callipteris属内,后来Kerp指出该属的属名有问题,便与Haubold提出了形态属Callipteris的重新划分方案,这一方案笔者表示完全同意.A.conferta是欧美植物群中早二叠世常见分子,在中欧的少数地点亦见于上石炭统上部,在中国则极少发现,仅见报道于河北开平赵各庄群上部和山西太原下石盒子组.D.flabellifera是欧美植物群中的另一早二叠分子,在西欧和北美的上石炭统上部亦见少数先驱分子,在华夏植物群中从未发现过.本文记载为其在国内首次记录.上述发现在古植物地理上具有一定意义.     

徐淮地区二叠系烃源岩地球化学特征及页岩气资源潜力——以宿州3-1钻井剖面为例

徐淮地区在构造上属于南华北板块,拥有华东最重要的煤炭基地徐州煤田、淮北煤田与淮南煤田,二叠系煤系烃源岩普遍发育,但针对该地区二叠系页岩气形成的地质条件的研究成果少见。通过对宿州3-1钻孔二叠系山西组、下石盒子组和上石盒子组泥页岩进行系统采样,开展了有机质丰度、类型和成熟度等地球化学分析测试,揭示该地区二叠系有效的富有机质泥页岩层段发育在山西组和下石盒子组,有机碳含量较高,山西组优于下石盒子组;有机质主要为Ⅲ型干酪根,处于成熟至高成熟阶段,具有较高的生烃潜力。     

大同煤田构造控煤特征研究

大同煤田位于山西省北部,主要含煤地层为石炭系太原组、二叠系山西组和侏罗系大同组。依据大同煤田构造发育特点,分析了区域构造对煤田构造格局的控制作用。研究认为,大同煤田主体为一向斜构造,控制了煤系的分布范围。区内控煤构造样式包括压缩构造和伸展构造两大类,前者分布于煤田边界,主要包括逆冲前锋构造、逆冲叠瓦构造、双冲构造、叠瓦扇构造等类型;后者主要分布在煤田内部,以正断层控制的堑垒构造类型为主,构成井田边界或采区边界。     

Lower Permian stems as fluvial paleocurrent indicators of the Parnaíba Basin,northern Brazil

A comprehensive biostratinomic study was carried out with abundant stems from the Lower Permian Motuca Formation of the intracratonic Parnaíba Basin, central-north Brazil. The fossils represent a rare tropical to subtropical paleofloristic record in north Gondwana. Tree ferns dominate the assemblages (mainly Tietea, secondarily Psaronius), followed by gymnosperms, sphenophytes, other ferns and rare lycophytes. They are silica-permineralized, commonly reach 4 m length (exceptionally more than 10 m), lie loosely on the ground or are embedded in the original sandstone or siltstone matrix, and attract particular attention because of their frequent parallel attitudes. Many tree fern stems present the original straight cylindrical to slightly conical forms, other are somewhat flattened, and the gymnosperm stems are usually more irregular. Measurements of stem orientations and dimensions were made in three sites approximately aligned in a W–E direction in a distance of 27.3 km at the conservation unit “Tocantins Fossil Trees Natural Monument”. In the eastern site, rose diagrams for 54 stems indicate a relatively narrow azimuthal range to SE. These stems commonly present attached basal bulbous root mantles and thin cylindrical sandstone envelopes, which sometimes hold, almost adjacent to the lateral stem surface, permineralized fern pinnae and other small plant fragments. In the more central site, 82 measured stems are preferentially oriented in the SW–NE direction, the proportion of gymnosperms is higher and cross-stratification sets of sandstones indicate paleocurrents mainly to NE and secondarily to SE. In the western site, most of the 42 measured stems lie in E–W positions. The predominantly sandy succession, where the fossil stems are best represented, evidences a braided fluvial system under semiarid conditions. The low plant diversity, some xeromorphic features and the supposedly almost syndepositional silica impregnation of the plants are coherent with marked dry seasons. Thick mudstones and some coquinites below and above the sandy interval may represent lacustrine facies formed in probably more humid conditions. The taphonomic history of the preserved plants began with exceptional storms that caused fast-flowing high water in channels and far into the floodplains. In the eastern site region, many tree ferns only fell, thus sometimes covering and protecting plant litter and leaves from further fragmentation. Assemblages of the central and western sites suggest that the trees were uprooted and transported in suspension (floating) parallel to the flow. Heavier ends of stems (according to their form or because of attached basal bulbous root mantle or large apical fronds) were oriented to upstream because of inertial forces. During falling water stage, the stems were stranded on riverbanks, usually maintaining the previous transport orientation, and were slightly buried. The perpendicular or oblique positions of some stems may have been caused by interference with other stems or shallow bars. Rare observed stems were apparently waterlogged before the final depositional process and transported as bedload. The differences of interpreted channel orientations between the three sites are expected in a braided fluvial system, considering the very low gradients of the basin and the work scale in the order of tens of kilometers. The mean direction of the drainage probably was to east and the flows apparently became weaker downstream. This study seems to provide reliable data for paleocurrent interpretations, especially considering areas with scarce preserved sedimentary structures.     

Diversities in biomarker compositions of Carboniferous–Permian humic coals in the Ordos Basin,China

The molecular composition of Carboniferous–Permian coals in the maturity range from 0.66 to 1.63% vitrinite reflectance has been analysed using organic geochemistry to investigate the factors influencing the biomarker compositions of humic coals. The Carboniferous–Permian coal has a variable organofacies and is mainly humic-prone. There is a significant difference in the distribution of saturated and aromatic hydrocarbons in these coals, which can be divided into three types. The Group A coals have biomarker compositions typical of humic coal, characterised by high Pr/Ph ratios, a lower abundance of tricyclic terpanes with a decreasing distribution from C₁₉ tricyclic terpane to C₂₄ tricyclic terpane and a high number of terrigenous-related biomarkers, such as C₂₄ tetracyclic terpane and C₂₉ steranes. The biomarker composition of Group B coals, which were deposited in a suboxic environment, have a higher abundance of rearranged hopanes than observed in Group A coals. In contrast, in Group C coals, the Pr/Ph ratio is less than 1.0, and the sterane and terpane distributions are very different from those in groups A and B. Group C coals generally have abnormally abundant tricyclic terpanes with a normal distribution maximising at the C₂₃ peak; C₂₇ steranes predominates in the m/z 217 mass fragmentograms. The relationships between biomarker compositions, thermal maturity, Pr/Ph ratios and depositional environments, indicate that the biomarker compositions of Carboniferous–Permian coals in Ordos Basin are mainly related to their depositional environment. This leads to the conclusion that the biomarker compositions of groups A and B coals collected from Shanxi and Taiyuan formations in the northern Ordos Basin are mainly related to their marine–terrigenous transitional environment, whereas the biomarker compositions for the Group C coals from Carboniferous strata and Shanxi Formation in the eastern Ordos Basin are associated with marine incursions.