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青海茫崖地区侏罗系是柴达木盆地北缘含煤岩系的西北延伸部分,地处阿尔金山南麓山前坳陷.青海省煤田地质区划将其称为格斯煤田,中一下侏罗统是本区唯一的含煤地层.对植物化石组合1及植物化石组合2进行了种属和组合特征分析研究,通过与邻区生物地层的对比分析,植物化石组合1与枝脉蕨顶峰带(Cladophlebis Acme Zone)植物组合类似,时代大体相当于普林斯巴赫期.植物化石组合2与锥叶蕨顶峰带(Coniopteris Acme Zone)可进行对比,地质时代为巴柔—巴通期.通过对茫崖地区基本地层层序与植物化石组合的分析研究,进一步对该区成煤地质时代进行了讨论. 相似文献
114.
Based on archaeological excavations, 217 samples were collected from the Luotuodun Site. Of them 63 samples from the section
plane of the site layer were used for identification analysis of foraminifera, plant debris and seed fossils, and four samples
were used for 14C dating and relevant analysis. Through many kinds of experiments, we have drawn some conclusions. Firstly, benthic foraminifera,
such as Ammonia compressiuscula and Ammonia cff. sobrina, are found in the 10th layer, indicating that between 7500 and 5400 BC, i.e. before the emergence of the Majiabang Culture,
Luotuodun Site and its nearby regions had ever experienced a marine transgression event. Secondly, we have found 450 plant
fossils in this site, such as Polygonum sp., Scripus sp., Najas sp., Physalis sp., which indicated lacustrine or swamp environment. 相似文献
115.
碱式水解法提取红土分子化石: 以安徽宣城更新世网纹红土为例 总被引:1,自引:0,他引:1
红土中种类丰富的分子化石为红土古生态研究提供了直接证据, 但较低含量的分子化石限制了传统索氏抽提方法的推广应用.本次研究尝试性地运用碱式水解法提取安徽宣城更新世红土中的分子化石, 在25g样品中检测到了含量明显、种类丰富的有机物, 且该方法可以显著地降低空白污染, 这说明碱式水解法在分子化石含量低的地质体(如红土) 研究中具有一定的应用潜力.本次研究检测出除了传统索式抽提得到的正构烷烃、脂肪酸、脂肪醇等以外, 还提取到了二元羧酸这一重要化合物, 它的存在为网纹红土可能形成于多水环境提供了新的证据.测试样品中各类分子化石组合信息显示出红土有机物以微生物为主的来源特征, 表明网纹红土形成过程受到了微生物活动的影响, 同时伴有大量低等菌、藻来源有机质的输入, 初步结果为红土形成环境研究提供了新的证据. 相似文献
116.
Rory N. Mortimore 《Proceedings of the Geologists' Association. Geologists' Association》2019,130(3-4):406-450
Extraordinary, long-distance litho-marker beds such as the Lewes and Shoreham Tubular Flints and associated marl seams and fossils, recognised in cliff exposures and cliff-fall boulders, are keys to unlocking the stratigraphy and tectonic structures in the Late Cretaceous of the Dorset and East Devon Coast World Heritage Site (Jurassic Coast). Durdle Cove is a special gem exposing the Lewes and Seaford Chalk stratigraphy where new marker beds are identified and sediments and tectonic structures provide clues to timing of movements that produced a Late Cretaceous pericline which grew into a Miocene monocline along the line of the underlying Purbeck Reverse Fault. During ‘inversion’ along this fault some Late Cretaceous Chalk formations were in part or completely ‘lost’ (e.g. Middle Turonian New Pit Chalk Formation) and others were condensed (e.g. Late Santonian and Early Campanian Newhaven Chalk Formation). Excavation of the A354 road cutting at the Lower Bincombe Farm, has greatly added to the stratigraphical records of Late Cretaceous fossils in South Dorset, especially Coniacian and Early Campanian inoceramid bivalves and the various stratigraphically specific forms of the Late Santonian to Early Campanian echinoid fossil Echinocorys scutata spp. not recorded before in this coastline. The very large bivalve fossil Platyceramus sp. provides clues to chalk sea-floor environments. 相似文献
117.
The Ordovician Daylesford Limestone at Bowan Park and the Fossil Hill Limestone at Cliefden Caves have diagenetic and pedogenic features of microkarst, paleosols and calcrete associated with subaerial disconformities in their stratigraphic sequences, all of which, as an ensemble, have global geoheritage significance. The original shelly limestones, lime mudstones, and coralline limestones have selectively dissolved to form vugular limestone whose cavities have filled with sparry calcite and/or crystal silt. The limestones also have been calcretised to develop massive and laminar calcrete and calcrete ooids. Below disconformity surfaces are bleached limestone, crystal-silt and spar-filled fossil moulds and enlarged moulds, micro-breccia-filled moulds and fissures filled with crystal silt, calcrete pellets and calcrete ooids. The disconformity surfaces are irregular or undulating interfaces between lithologies, fissures and fissure-fills, and calcrete. Above disconformities there are limestone lithoclasts, remanié fossils, calcreted limestone, veined limestone, calcrete ooids, laminated calcrete, lithoclast grainstone, or calcrete-ooid grainstone, and lithoclasts with fossils moulds filled with crystal silt and/or spar. The lithological, stratigraphic and possibly landscape differences, make the subaerial diagenesis/pedogenesis in the Daylesford Limestone subtly different to that of the Fossil Hill Limestone. Subaerial disconformities and associated diagenesis/pedogenesis, as recorded in these formations, are not widely reported globally nor well represented in Ordovician limestones. The microkarst features provide insights into the types of subaerial diagenesis/pedogenesis during the Ordovician and into climate, landscape setting, paleohydrology, and groundwater/rainwater alkalinity. Consequently, the story of the Ordovician microkarst, paleosols and calcrete ooids is unique and globally of geoheritage significance as examples of subaerial alteration in an ancient high-rainfall, tropical climate volcanic island environment in a tectonically active region. 相似文献
118.
The carbonate concretions occurring at the bottom of Talchir fissile shale facies preserved signatures of various trace fossils
along with a cast of doubtful organisms and cyanobacterial mat structures. The host shale deposited under glacial melt water
fed lacustrine condition. The concretions, formed in poorly oxygenated conditions, are either of syndepositional origin and/or
deposited a little below the sediment water interface and were later exhumed to the depositional surface due to erosion of
soft mud overlying them.
The trace fossils are both megascopic and microscopic in nature. The megascopic trace fossils are identified on the basis
of their morphology as Monocraterion and Rhizocorallium. Some of the megascopic structures described remain problematic at present. The microscopic trace fossils are formed due
to the activity of marine meiofauna (possibly by nematodes), which, although produced morphologically show similar traces
of known larger ichnogeneras but much smaller than them. The discovery of these trace fossils apparently indicate the influx
of saline water into a lacustrine domain during the Talchir sedimentation at Giridih basin. Moreover, presence of the above
two megascopic trace fossils in the marine lacustrine carbonate concretions may lead researchers to consider their much wider
environmental significance than hitherto believed. 相似文献
119.
滇东、川中地区震旦系——寒武系界线附近的遗迹化石 总被引:15,自引:1,他引:14
本文描述的遗迹化石采自滇东地区和四川中部峨眉、乐山地区的震旦系—寒武系界线附近。经鉴定有23个遗迹属、31个遗迹种,其中两个新遗迹属、5个新遗迹种。在系统描述的基础上,还进行了遗迹化石的习性类型解释。这些习性类型包括觅食迹、牧食迹、居住迹和游泳迹。 相似文献
120.