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George R. McGhee JR. 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1976,9(2):111-136
Four benthic marine communities occur in the clastic facies of the prograding Upper Frasnian-Lower Famennian (Upper Devonian) Foreknobs Formation in the Central Appalachians along the Allegheny Front in Maryland, West Virginia, and Virginia. Deep-water, rapidly prograding environments were inhabited by the Ambocoelia-Chonetes Community, dominated by an epifauna of unattached brachiopods. Offshore bar environments were inhabited by the Cyrtospirifer-Camarotoechia Community, exhibiting adaptations to shallow-water, high-energy conditions and probably lowered salinities. Shallow-water, sublittoral environments were inhabited by the Atrypa-Cypricardella Community, a community in which existed a variety of life habitats and a diverse epifaunal and infaunal association of brachiopods and bivalve molluscs. The Leptodesma-Tylothyris Community flourished in nearshore bar-protected environments in the southern region of the study area, whereas in the north the Cyrtospirifer-Camarotoechia Community inhabited nearshore environments in conjunction with the onshore development of a large fluviodeltaic system. 相似文献
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对采自四川盆地云阳一带自流井组东岳庙段14属18种植物化石进行了研究,其中描述1个新种Stachypteris? anomala Meng(sp.nov.)和1个首见于区内的种Klukia exilis(Phillips)。东岳庙段植物组合的重要分子是从下伏珍珠冲段延续而来的,这表明此组合基本承袭了珍珠冲段的组合面貌。依据Dictyophyllum nilssoni,D.nathorsti,Otozamites hsiangchiensis等尚未见于中侏罗世和自流井组明显分为两大沉积旋回,指出东岳庙段的时代属早侏罗世托尔期(Toarcian)和四川盆地下-中侏罗统的界线以划在自流井组东岳庙段与马鞍山段之间为宜。 相似文献
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《Palaeoworld》2016,25(1):76-83
Some typical components of the Jehol Biota, including conchostracans Eosestheria sp., the mayfly Ephemeropsis trisetalis Eichwald, 1864, the aquatic beetle Coptoclava longipoda Ping, 1928, and a fragmentary dragonfly, are reported for the first time from the Bayingebi Formation in the Celaomiao region, western Inner Mongolia, China. This discovery indicates that the middle Upper Member of Bayingebi Formation can be correlated with the upper Yixian and the lower Jiufotang formations in western Liaoning Province. Combining it with the radio-isotopic dating result, we further believed that the Upper Member of Bayingebi Formation could be roughly correlated with the Yixian, Jiufotang, and Shahai formations, and the overlying Suhongtu Formation with the Fuxin Formation in western Liaoning Province.In the major Bayingebi Basin, palaeontological and radio-isotopic dating evidence shows that the Bayingebi Formation has a long depositional history of over 30 Ma: its Upper Member bearing the Jehol Biota and the early Fuxin Biota is probably coeval to the Yixian, Jiufotang and Shahai formations and has a Barremian–early Albian age; its Lower Member may be Berriasian–Hauterivian in age and could be correlated with the upper Tuchengzi, Zhangjiakou, and Dabeigou formations in northern Hebei Province. This suggests that the Bayingebi Formation should be promoted to the stratigraphic rank of group and subdivided into several secondary units (formations). Unlike the previous result, the Yingen Formation is considered across the Lower Cretaceous–Upper Cretaceous boundary and being late Albian–early Turonian in age. 相似文献
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Birendra P. Singh Om N. Bhargava Scott Morrision Ramanpreet Kaur Garry Singla 《Ichnos》2020,27(1):1-34
AbstractIntegrated ichnology, sedimentology and sequence stratigraphy of the Lower Quartzite Member to the Arkosic Sandstone Member of the Koti Dhaman Formation (Cambrian Series 2, Stage 4), Tal Group, Nigali Dhar Syncline, Lesser Himalayan lithotectonic zone are presented. Trilobite traces of Gondwanan affinity i.e., Cruziana salomonis, Cruziana fasciculata, Rusophycus dispar and Rusophycus burjensis are recorded along with Arenicolites isp. and Skolithos isp. from the Lower Quartzite Member. A rich and diverse ichnoassemblage attributed to the Cruziana ichnofacies is described for the first time from the Arkosic Sandstone Member of the same formation. Seven ichnofossil assemblages, i.e., Cruziana-Rusophycus, Planolites-Palaeophycus, Cruziana problematica, Diplichnites, Cochlichnus anguineus, Bergaueria perata and Psammichnites gigas have been recognized in the Lower Quartzite to Arkosic Sandstone members of the Koti Dhaman Formation. Seven sedimentary facies i.e., sandstone–shale facies (FT1), cross-bedded (trough and planar) sandstone (FT2), bedded sandstone facies (FT3), shale facies (FT4), shale–sandstone facies (FT5), shale-rippled sandstone facies (FT6) and planar and trough cross-laminated sandstone (FT7) and four facies associations FA1-FA4 are identified in the Koti Dhaman Formation. The formation contains shallowing upward parasequences of a tidal flat complex. Overall, two major events are recognized: i) the break in sedimentation between the Lower Quartzite Member and the overlying Shale Member probably related to forced-regressive event and ii) the facies shift from FT6 to FT7 of the Arkosic Sandstone Member represents an erosive transgressive event; the surface is interpreted as wave ravinement surface, which also serves as a sequence boundary. Integrated ichnology, sedimentology and sequence stratigraphic studies indicate that the Lower Quartzite Member was deposited in a shallow subtidal sand sheet complex and tidal flat complex; the Shale Member was deposited in a mud flat setting of a tidal flat complex, and the Arkosic Sandstone Member in a mixed-flat (tidal flat complex) to sand sheet complex front and margin (subtidal sand sheet complex). Overall, the lower to middle part of the Koti Dhaman Formation represents a tide-dominated shallow subtidal–intertidal to mud-flat subenvironments of the tidal flat complex. A palaeogeographic reconstruction of lower Cambrian (516–514?Ma) is presented based on the distribution of trilobite traces from the Lesser Himalaya and the Bikaner–Nagaur area of Peninsular India (eastern Gondwana), Egypt, Jordan, Turkey (western Gondwana) and Canada (Avalonia). 相似文献
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J. A. Fagerstrom 《Coral reefs (Online)》1983,2(2):65-70
Lower Devonian late Emsian (Bois Blanc and Clear Creek Limestones; Schoharie Formation) level-bottom communities in New York, Michigan and Illinois were moderately cosmopolitan and diverse and dominated by brachiopods and solitary rugose corals. Subsequently (Early Eifelian?), there was an important episode of cratonal patch reef building in New York (Edgecliff Member, Onondaga Limestone), southwestern Ontario (Formosa Reef Limestone, lower Detroit River Group), and the Hudson Bay Lowland (Kwataboahegan Formation) by highly diverse endemic communities. The Edgecliff reefs were built by corals whereas the Formosa and Kwataboahegan reefs were built primarily by stromatoporoids. The strong correlation between high diversity and high endemism during the reef-building episode suggests that these communities contained numberous, small species populations belonging to several major taxa — an example of rapid speciation by geographic isolation and genetic drift. 相似文献
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《微体古生物学报》2015,(2)
本文总结了塔里木盆地西北缘露头剖面和典型钻井(草1井与托甫2井)剖面柯坪塔格组岩电及生物特征,并在此基础上对中央隆起区32口主要钻井的柯坪塔格组进行连井地层划分对比及地震剖面标定追踪。结合对等T0图分析,探讨了研究区柯坪塔格组三段分布规律。研究表明,柯坪塔格组上段分布最广,除麻扎塔格-塘参1-顺南地区以南没有发育外,其余地区均有发育,地层厚度一般在100—300m不等,在顺托果勒地区及方1井区以北分布厚度最大,超过了300m。柯坪塔格组上段总体分布表现出南薄北厚、东西分布不均的特点。柯坪塔格组中段与柯坪塔格组下段分布局限,仅在和4-顺西1-顺南3-塔中32井以北地区有发育。柯坪塔格组中段厚度一般只有40—60m,柯坪塔格组下段厚度一般为200—300m,两者厚度均表现出南薄北厚的分布特点。 相似文献
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云南澄江及梅树村早寒武世黑林铺组(玉案山段及石岩头段)的帽形化石,被命名为云南太阳女神螺(新种),这是澄江生物群内软体动物化石的初次发现。根据梅树村及澄江的地层层位,该种由梅树村阶上部可延至筇竹寺阶,玉案山段软体动物稀少的原因与环境的波动,如潮汐影响近海沉积环境有关。 相似文献
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F E Grine 《American journal of physical anthropology》1989,79(4):409-449
Seventy-two individually numbered hominid craniodental fossils from recent excavations at Swartkrans are described. All derive from in situ decalcified breccia and/or unconsolidated sediments. A total of 20 specimens, representing 13 to 16 individuals derive from Member 1 "Lower Bank," two teeth derive from sediments along the Member 1-2 Interface, 38 fossils representing 19 to 24 individuals come from Member 2, and 12 teeth representing 9 to 11 individuals derive from Member 3. All but four of the specimens are attributable at the generic level; one specimen from Member 1 "Lower Bank" and five specimens from Member 2 are attributed to Homo, while the others represent Paranthropus. The proportional representation of Homo in the Swartkrans Formation is markedly higher in Member 2 (c. 33%) than in the Member 1 "Lower Bank" (c. 8%) and Member 1 "Hanging Remnant" (c. 5%) samples. 相似文献
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广西凤山、西林等地中三叠统上部双壳类分带研究* 总被引:7,自引:3,他引:4
讨论广西西部中三叠统上部的双壳类生物地层序列,建立5个化石带;并附述黔南和滇东南晚三叠世1个双壳类带.这些带自下而上为:(1) Daonella (Longidaonella) producta-D. americana 带,属晚安尼早中期;(2) D. moussoni 高峰带,属晚安尼晚期;(3) D. rieberi-D. indica 带,属早拉丁期;(4) D. kotoi-D. jilongensis 带,属晚拉丁早期;(5) Halobia subcomata-D. varifurcata带,属晚拉丁晚期;(6) H. rugosoides-H. bifurcata 带,属早卡尼期.文内简要描述了各带的主要标志化石23种. 相似文献
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Pierre J. Lespérance Peter M. Sheehan 《Palaeogeography, Palaeoclimatology, Palaeoecology》1975,17(4):309-326
Lower Devonian quiet-water marine benthic communities were examined to determine what parameters of community structure are maintained from locality to locality. The preserved elements of the communities are dominated by brachiopods. Each community has a characteristic taxonomic composition and diversity. From stratigraphically lowest to highest the communities include the newly proposed Dawsonelloides Community which has relatively low diversity, and is strongly dominated by a single species. The Beachia Community is less strongly dominated by a single species. The newly proposed Leptostrophia Community is very strongly dominated by a single species; less common species are rare or absent in the other communities. The Plicoplasia Community is slightly less diverse than the preceeding two communities, but unlike them has six species which dominate one or more collections and are commonly found in reduced abundance in the other collections. The gradual change in taxonomic composition and structure from one community to adjacent communities coupled with the similar structure of diversity and dominance within particular communities suggest that these characteristics are time-averaged and primary structural features of the communities. 相似文献
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One hundred and eight species of fossil spores and pollen referred to 55 genera found from the Lower Cretaceous Kapushaliang (Kizilsu) Group in the Tarim Basin of Xinjiang have been studied in this paper. The Kapushaliang Group may be divided into the Yageliemu Formation, the Shushanhe Formation and Baxigai Formation in ascending order. The Yageliemu palynoflora is characterized by the predominance of gymnospermous pollen, the relative abundance of pteridophytic spores and the absence of angiospermous pollen. Coniferae is dominant, while Lygodiaceae and Schizaeaceae are important in the flora. The most common species of palynomorphs are Todisporites minor, Cicatricosisporites dorogensis, C. australiensis, Lygodiumsporites subsimplex, Schizaeoisporites cretacius, S. zizyphinus, S. certus. Cibotiumspora paradoxa, Cyathidites australis, C. minor, Biretisporites potoniael, Cycadopites minimus, Pseudowalchia hiangulina, Parvisaccites radiatus, Podocarpidites multesimus, P. canadensis, Alisporites bilateralis, Cedripites cretaceus, C. canadenris, Abietineaepollenites microalatus, Clarsopollis classoides, C annulatus, C. xinjiangensis (sp. nov.), Ephedripites multicostatus, E. tarimensis (sp. nov.), etc . The palynoflora is comparable with those of the lower part of the Lower Xinminbu Formation in northwestern China and the lower part of the Lower Mannville Formation in western Canada, which is considered corresponding from Berriasian to Valanginian in age. The Shushanhe palynoflora is also characterized by dominance of gymnosperms and subdominance of pteridophyta. Some primitive angiospermons pollen grains are found in the upper part of the formation. In addition to the most common species of the above mentioned palynoflora, the important species in the present palynoflora comprise Cicatricosisporites potomacensis, C. orbiculatus, C. subrotundus, Concavissimisporites punctatus, C. verrucosus, C. globosus, lmpardecispora apiverrucata, Trilobosporites crassus, T. trioreticulosus, Pilosisporites verus, P. trichopapillosus, Klukisporites pseudoreticulatus, Verrucosisporites obscurilaesuratur, Converrucosisporites saskatchewanensis, Foraminisporis wonthaggiensis, Cingulatisporites valdensis, C. ruginosus, Jiaohepollis verus, Pityosporites constrictus, etc. More than 40 in dicative species of Early Cretaceous occur in the assemblage. The palynoflora compares clcsely with those of the middle part of the Lower Xinminbu Formation and the Quartz Sand Member of the Lower Mannville Formatton. It is suggested that the Shushanhe Formation should belong to Hauterivian of Barremian in age. The Baxigai palynoflora is basically similar to the Shushanhe palynoflora. But the palynoflora shows an obvious increase in abundance of lygodiaceous spores and angiospermous pollen accompanied by a great reduction of Classopollis and Ephedripltes. Most of the Early Cretaceous species occurring in the above mentioned palynofloras are present. In addition, some Cretaceous species recorded from Aptian and Albian Stages in Europe, North America and Australia, such as Trilobosporites tribotrys, T. trioreticulosus, Coptospora paradoxa, Camarozonosporites insignis, Crybelosporites punctatus, etc., appear in the assemblage. In comparison with the microfloras of the upper part of the Lower Xinminbu Formation, the Upper Mannville Formation and the lower part of the Lower Colorado Group, the Baxigai Forma- tion should be referred to Aptian to Albian in age. Judging from the palynofloras, the early Cretaceous palaeoclimate in the basin should belong to the arid or semi-arid type of the subtropic zone. However, from Barremtan through Albian the climatic conditions might appear relatively wet. 相似文献
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贵州独山的猴儿山组龙洞水段是一套浅海相碳酸盐沉积,盛产底栖牛物化石.通过对该段地层中所含四射珊瑚、床板珊瑚和腕足类等化石属种的详尽分析,再次证实龙洞水段的地质时代仍应属中泥盆世早期(Eifelian).而不是像某些根据痕迹化石或层序地层学的研究那样将它置于下泥盆统. 相似文献
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《Comptes Rendus Palevol》2014,13(8):737-746
The spatial relationships of the Early Oldowan toolmakers with their environment have been so far addressed through raw material procurement analyses and the characterization of hominid habitat. This paper proposes to integrate these two approaches into a broader spatial analysis encompassing archaeological and environmental data (palaeontological, geological and isotopic data) from Member F and lower Member G of the Shungura Formation (Lower Omo Valley, Ethiopia). Heterogeneity in data resolution induces a multiscale approach with three levels of analysis. The level of occurrence complex allows focusing on the characterization of archaeological occurrences and on their environmental settings. The level of “study area” allows working on hominid habitats and on their raw material procurement behaviours. Finally, at the Shungura Formation scale, we can address temporal issues related to the evolution of spatial behaviours between Member F and the lower part of Member G, ca. 2.3 to 2 million years (Ma). 相似文献
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Sedimentary facies and stratigraphic architecture of non-marine carbonates are controlled by a range of environmental parameters, such as climate, hydrology and tectonic setting, but the few published facies models do not account for this variability. Outcrop and petrographic observations from the Mupe Member of the Purbeck Limestone Group (Upper Jurassic–Lower Cretaceous) in Dorset, southern England, are the basis for new depositional models of non-marine microbialites and associated carbonates in an extensional basin. Ten facies are defined, described and grouped into five facies associations. The Mupe Member is characterised by accumulation of in situ microbial mounds developed around tree remains preserved as moulds and silicified wood. Mounds occur within three stratigraphic units, separated by three palaeosoils, characterised by less-porous, bedded, inter-mound packstone–grainstone that commonly onlap mound margins. Mounds are developed mainly in the shallowest areas of the lake, as indicated by their shapes, facies relationships and association with palaeosoils. These microbial mounds are compared to modern (Laguna Bacalar, Mexico and Great Salt Lake, Utah, USA) and ancient (Eocene Green River Formation, Uinta Basin, Utah, USA) analogues to assess their value as palaeoenvironmental indicators. Facies transitions indicate an earlier, brackish-water lake and a later hypersaline lake for the Mupe Member, both within a semi-arid climate setting in an extensional basin. The fact that the microbialites are covered by evaporitic strata, together with sedimentological, palaeontological and stable isotope data, suggest that there was a sharp change from through-flowing brackish-water, to a closed hypersaline, lacustrine system. 相似文献