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1.
湖北宜昌黄花场中/下奥陶统界线附近几丁虫组合及其地层学意义 总被引：4，自引：1，他引：4
对宜昌黄花场大湾组下段牙形石 Oepikodus evae带至 Baltoniodus triangularis带系统采集与分析几丁虫样品 ,共发现几丁虫 6属 12种 ,其中包括 1个相似种、1个未定种 ,它们是 Conochitina raymondii,C.ordinaria,C.primitiva,C.langei,C.brevis,C.poumoti,C.decipiens,Belonechitina cf.micracantha,L agenochitina esthoni-ca,L.sp.,Eremochitina baculata和 Cyathochitina dispar等。根据上述几丁虫的地质和地理分布特征 ,自下而上可划分为 Conochitina langei带和 Eremochitina baculata带 ,讨论并指出了他们与相关笔石、牙形石生物带的关系 相似文献
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江苏东台廉贻地区大湾组动物群的发现及其意义 总被引：2，自引：1，他引：2
<正> 1979年,在东台县廉贻公社张岳庄村边的荻3井2747—2827.5米井段钻遇一套灰岩地层,在岩芯中,陈永祥首次发现三叶虫和腕足类化石,古生物组确定该段地层为大湾组。我们对该井段的岩芯和岩屑进行了系统分析,获得了多种化石。其中大湾组牙形刺14属16种(包括4个未定种),三叶虫5属5种(包括1个未定种),腕足类5属,腹足类2属, 相似文献
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《Journal of Asian Earth Sciences》2007,29(4-6):259-275
With a thickness of 3900 m, the Tazareh section is one of the thickest developments of the Shemshak Formation in the Alborz range. It overlies with sharp and disconformable contact the limestones and dolomites of the Lower–Middle Triassic Elikah Formation and is topped, again with a disconformable contact, by the marls and limestones of the Middle Jurassic Dalichai Formation. The nearly exclusively siliciclastic succession represents a range of environments, from fluvial channels, flood plains, swamps and lake systems to storm-dominated shelf, and a comparatively deep marine and partly dysoxic basin. The segment of the section between 2300 and 3500 m is exclusively marine and contains a moderately diverse ammonite fauna, ranging from the Middle Toarcian to the Upper Aalenian. The ammonite fauna comprises 21 taxa, among them the new genus Shahrudites with two new species, Shahrudites asseretoi and S. stoecklini from the Middle Aalenian Bradfordensis Zone. The other ammonites from the Shemshak Formation at Tazareh (as elsewhere in North and Central Iran) are exclusively Tethyan in character and closely related to faunas from western and central Europe. An ammonite-based correlation of Toarcian–Aalenian successions of the eastern Alborz with time-equivalent strata of the Lut Block, part of the Central-East Iranian Microcontinent (ca. 500 km to the south), suggests a strong influence of synsedimentary tectonics during the deposition of the upper Shemshak Formation. 相似文献
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A proposed GSSP for the base of the Middle Ordovician Series： the Huanghuachang section,Yichang, China 总被引：2，自引：0，他引：2
XiaofengWang SvendStouge Bernd-D.Erdtmann XiaohongChen ZhihongLi ChuanshangWang QingluanZeng ZhiqiangZhou HuimingChen 《《幕》》2005,28(2):105-117
The Huanghuachang section near Yichang, southern China meets the requirements of Global Stratotype Section and Point (GSSP) for the base of the Middle Ordovician Series and the yet-to-be-named third stage of the Ordovician System (or lower stage of Middle Ordovician Series). The conodont succession at the section is complete across the Lower to Middle Ordovician series boundary and several excellent phylogenetic lineages of Baltoniodus, Trapezognathus, Periodon, and Microzarkodina are represented. The definition of the base of the Middle Ordovician is proposed to be the first appearance datum (FAD) of Baltoniodus? triangularis in the section. It is followed closely by the FAD of Microzarkodina flabellum, which is taken as a reasonable proxy for the boundary. This level approximates the boundary between the lower and upper intervals of the Azygograptus suecicus graptolite Biozone, and nearly coincides with the base of the Belonechitina henryi chitinozoan Biozone.The proposed GSSP for the base of the international Middle Ordovician Series is located in a roadside exposure at the base of Bed (SHod) 16, 10.57 m above the base of the Dawan Formation in the measured Huanghuachang section near Yichang City, southern China. The same faunal succession is also recorded from the Chenjiahe (formerly Daping) section, 5 km to the north of the Huanghuachang section. The proposed boundary horizon can be recognized and correlated globally with high precision in both relatively shallow-water carbonate facies as well as in deep-water graptolite facies. 相似文献
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The Ordovician Ponón Trehué Formation is the only early Palaeozoic sedimentary sequence known to record a primary contact with the Grenvillian-age basement of the Argentinean Cuyania terrane, in its southwards extension named the San Rafael block. Petrographic and geochemical data indicate contributions from a dominantly upper continental crustal component and a subordinated depleted component. Nd isotopes indicate εNd of ? 4.6, ?Sm/Nd ? 0.36 and TDM 1.47 Ga in average. Pb-isotope ratios display average values for 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb of 19.15, 15.69 and 38.94 respectively. U–Pb detrital zircon ages from the Ponón Trehué Formation cluster around values of 1.2 Ga, indicating a main derivation from a local basement source (Cerro La Ventana Formation). The Upper Ordovician Pavón Formation records a younger episode of clastic sedimentation within the San Rafael block, and it shows a more complex detrital zircon age population (peaks at 1.1 and 1.4 Ga as well as Palaeoproterozoic and Neoproterozoic detrital grains). Detailed comparison between the two Ordovician clastic units indicates a shift with time in provenance from localized basement to more regional sources. Middle to early Upper Ordovician age is inferred for accretion of the Cuyania terrane to the proto-Andean margin of Gondwana. 相似文献
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LEE Jeong-Hyun HONG Jongsun WOO Jusun OH Jae-Ryong LEE Dong-Jin CHOH Suk-Joo 《《地质学报》英文版》2016,90(1):352-367
Various early Paleozoic (Cambrian Series 3–Middle Ordovician) reefs are found in the Taebaek Group, eastern Korea, located in the eastern margin of the Sino-Korean Block. They occur in every carbonate-dominant lithostratigraphic unit of the group, but their morphology and composition differ markedly. The Daegi Formation (middle Cambrian: Cambrian Series 3) contains siliceous sponge-Epiphyton reefs formed in a shallow subtidal environment, which is one of the earliest metazoan-bearing microbial reefs after the archaeocyath extinction. The Hwajeol Formation (upper Cambrian: Furongian) encloses sporadic dendrolites consisting of Angulocellularia, which developed in a relatively deep subtidal environment, representing a rare deeper water example. The onset of the Ordovician radiation resulted in the formation of microbialite–Archaeoscyphia–calathiid patch reefs in shallow subtidal deposits of the Lower Ordovician Dumugol Formation. Subsequent late Early Ordovician relative sea-level fall established extensive peritidal environments, forming microbial mats and stromatolites of the Lower–Middle Ordovician Makgol Formation. Ensuing Ordovician radiation resulted in one of the earliest metazoan skeletal reefs of the Middle Ordovician Duwibong Formation, constructed by stromatoporoid Cystostroma and bryozoan Nicholsonella, and developed around shallow shoals. These reefs reflect ongoing evolution and sea-level change during the early Paleozoic, and exemplify a rare glimpse of peri-Gondwanan records of reef evolution, which warrant detailed investigations and comparison with their counterparts in other regions. 相似文献
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《Journal of South American Earth Sciences》2007,23(1):1-16
The Uquía Formation crops out in the Quebrada de Humahuaca in Jujuy province, Eastern Cordillera, NW Argentina. This unit is composed of a sequence of fluviatile sediments and water-laid air-fall tuff beds; it is approximately 260 m thick and unconformably overlain by Pleistocene conglomerates and Quaternary alluvium. The sediments have been folded into a syncline and broken by several faults that generally trend northwest–southeast. Following Castellanos stratigraphy, we characterize three units (Lower, Middle, and Upper) of the Uquía Formation. Biochronologically, the Lower Unit is assigned to the late Chapadmalalan, the Middle Unit (“Uquian fauna”) to the late Vorohuean and Sanandresian, and the Upper Unit to the Ensenadan. Biostratigraphic evidence provides a calibration of important biochronologic events in the Great American Biotic Interchange (GABI), namely, the first appearances of Erethizon, Hippidion, and proboscideans at 2.5 Ma (late Pliocene) in South America. Geological and paleobiological evidence suggest that during the late Pliocene, the area could have been a wide intermountain valley at 1400–1700 m elevation, with a more humid environment than that of the present day and some wet–dry seasonality that permitted the coexistence of forest and open areas. Uquian mammals also indicate that northwestern Argentina and the Pampean region have represented distinct biogeographical areas since at least the late Pliocene. 相似文献
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Seven specimens of fossil scorpionflies (Mecoptera) not assignable to any known family were discovered in the Wealden Supergroup (Lower Cretaceous) of southern England. They were found at Rudgwick Brickworks, West Sussex and Smokejacks Brickworks, Surrey and came from the Upper Weald Clay Formation, dated as Barremian (∼129.4–125 Ma). A new family – Englathaumatidae fam. nov., new genus – Englathauma gen. nov. and two new species E. crabbi sp. nov. and E. mellishae sp. nov. are described. A discussion of systematic position of these new taxa within the order Mecoptera is given. Englathaumatidae fam. nov. has been a nomen nudum since the year 2002, due to the first author's untimely death. 相似文献
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A new genus, Cretasyne gen. nov., in the family Lasiosynidae, with two species C. lata sp. nov. and C. longa sp. nov., is described from the Lower Cretaceous Yixian Formation of Inner Mongolia, China. These fossils are the first record of the family from the Yixian Formation and provide significant information on lasiosynid morphology and diversity. The fossil record of Lasiosynidae is also reviewed. 相似文献
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24-n-Propylcholestane (24-npc), a C30 sterane compound derived from sterol precursors which are the major sterol constituents of modern pelagophyte microalgae, occurs in certain Neoproterozoic rocks and oils and throughout the Phanerozoic rock record. This broad distribution leads 24-npc to be widely considered a reliable indicator of open to partially restricted marine depositional conditions for source rocks and oils. Here we report two significant hiatuses in the occurrences of 24-npc in the Lower Paleozoic marine rock record: the first in the Middle–Late Cambrian and the second in the Late Ordovician–early Silurian transition for a range of lithofacies (carbonates and siliciclastic rocks), organic carbon contents (both organic-lean and organic-rich), and paleoceanographic environments (shelf and deeper water marine settings) and observed offshore of two paleocontinents, Laurentia and Baltica. The Ordovician–Silurian gap is at least 9 million years, and possibly up to 20 million years, in duration. Robust older occurrences of 24-npc steranes in some Neoproterozoic rocks and oils suggest that oceanographic conditions in our intervals of Lower Paleozoic time were unfavorable for the proliferation of pelagophyte algae as phytoplankton. Caution should therefore be applied when interpreting a lacustrine versus marine depositional environmental setting for source rocks and oils in these intervals of Early Paleozoic time using lipid biomarker assemblages. 相似文献
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喀喇昆仑山基本上属于地质空白区.1982年新疆地质矿产局区调大队四分队所采获的三叶虫等化石,描述了9属9种,其中5个新种,3个未定种,化石组合可以分为三个化石带:3.Lituites带;2.Ptychopyge-Chislioceras-Dideroceras带;1.Psilocephalina-Yinjiangia带.属于扬子型动物群. 相似文献
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《Journal of Asian Earth Sciences》2007,29(1):127-135
Lower Devonian corals and stromatoporoids have recently been discovered in limestones among low grade metamorphic rocks on the western margin of the Kon Tum Block (South Viet Nam). This unit has been identified as the Cu Brei Formation. Coral and stromatoporoid species have been described including Squameofavosites aff. spongiosus, Parallelostroma cf. multicolumnum, Amphipora cf. rasilis, A. cf. raritalis, Simplexodictyon cf. artyschtense, Stromatopora cf. boriarchinovi and Stromatopora sp. indet. The Cu Brei Formation is exposed in a small area 6 km in length and 3 km wide at the foot of Cu Brei Mountain (Sa Thay District, Kon Tum Province). As this formation is in marine shelf facies it is probable that further exposures of Lower Devonian sediments may be discovered in the Kon Tum Block. This discovery raises the question of the tectonic history of the metamorphic Kon Tum Block. It is possible that the block was not an area of positive uplift from the beginning of Paleozoic as has been supposed, but was submerged in a marine environment, at least on its outer margins, in the Devonian, and possibly even earlier, in Early Paleozoic. 相似文献
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Oil Source and Entrapment Epoch of the Ordovician Oil Reservoir in the Kongxi Burial-Hill Zone, Huanghua Depression, North China 总被引：6，自引：0，他引：6
WANG Tieguan WANG Feiyu LU Hong The Key Laboratory of Petroleum Entrapment Mechanism of Ministry of Educationin the University of Petroleum Beijing YANG Chiyin LIAO Qianjin ZHOU Jiansheng Geological Research Institute Dagang Oilfield 《《地质学报》英文版》2001,75(2):212-219
An oil flow obtained from the Middle Ordovician Fengfeng Formation carbonate reservoir in the well KG-3, Kongxi burial-hill zone in 1993 marked a breakthrough in petroleum exploration of the high-mature Lower Palaeozoic strata, North China. Both the Lower member of the Fengfeng Formation and the Second Member of the Upper Majiagou Formation in the Middle Ordovician are supposed to be the main source beds. Oil generation peaks range from 1.0% to 1.6% in Ro, showing a "lag effect" of oil generation in high-mature carbonate source rocks under multicyclic tectonic movement conditions. The Kongxi burial-hill zone adjoins a potential Ordovician source kitchen. The KG-3 Ordovician burial-hill reservoir has undergone two oil filling events, i.e., an early event in the Late Carboniferous-Permian and a more significant late event in the early Eogene. 相似文献
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9172 Conodonts have been recovered from the uppermost Hunghuayuan Formation and the Zitai Formation at two sections in Shitai County, southern Anhui Province, South China, which was situated close to the margin of the Lower Yangtze Platform during the Early to Middle Ordovician. Systematic and multivariate statistical studies on these conodonts permit recognition of seven conodont biofacies: Tropodus biofacies, Diaphorodus biofacies, Oepikodus biofacies, Baltoniodus biofacies, Paroistodus biofacies, Periodon biofacies and Protopanderodus biofacies. Each biofacies is restricted to a particular lithofacies and stratal position and shows a consistent order and/or position within the succession. Turnover of these conodont biofacies is related to sea-level changes. The transgressive–regressive patterns demonstrated by the conodont biofacies compare closely to published sea level curves for South China, and highlight the utility of conodont biofacies as a means of confirming sedimentological evidence of relative sea-level change. 相似文献
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Here we report a large dinosaur tracksite from an extensive fluvial sandstone surface in the Lower Cretaceous Jiaguan Formation of Sichuan Province, China. The site contains over 250 individual tracks comprising at least 18 recognizable trackways, including the longest theropod trackway (cf. Eubrontes) known from China. This exceptional theropod trackway consists of 81 successive footprints covering a distance of 69 m. The tracks are well-preserved and are expressed both as true tracks on the main “upper” surface and as transmitted undertracks on a locally exposed “lower” bed. Also recorded are six other theropod trackways, including small Grallator-like ichnites, eight sauropod trackways (cf. Brontopodus), and three small ornithopod (cf. Ornithopodichnus) trackways with a parallel orientation, which may indicate gregarious behavior. Several trackways of a larger theropod trackmaker show pes imprints with elongated traces of the metatarsals, suggesting extramorphological (substrate-controlled) variation and/or plantigrade posture, which is here interpreted as indicating a change in gait assumed in response to deep and soft sediment. The assemblage indicates a diverse dinosaur fauna in the Lower Cretaceous Sichuan Basin with variously sized theropods, sauropods, and ornithopods. The late occurrence of footprints of the Grallator-Eubrontes plexus in Lower Cretaceous strata is further evidence of the extended stratigraphic range of this morphotype and the distinct palaeobiogeographic distribution of these trackmakers in East Asia. 相似文献
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Mongkol Udchachon Punya Charusiri Hathaithip Thassanapak Clive Burrett 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(2):215-226
Lower Palaeozoic rocks have been mapped in Kayin State in an area previously shown on published maps as either metamorphic or possibly Lower or Upper Palaeozoic rocks. Three new formations, with a total thickness of over 900?m, apparently overlain by an, at least, 100?m thick Upper Palaeozoic formation are mapped along the Salween River and along the road from Yinbaing, in Myanmar, to Tha Song Yang, in Thailand. The Lower Palaeozoic succession consists of the predominantly siliciclastic Kyaukpulu and Kushwe–e–we formations and an overlying, predominantly carbonate Meseik Ashe Formation which contains Middle Ordovician (Darriwilian) conodonts. The older two formations are probable correlates of the Ngwetaung and Lokeypin formations of the southern Shan State of Myanmar and the Lower Ordovician siliciclastics of western Thailand. The overlying, peritidal to shallow subtidal carbonates of the Meseik–Ashe Formation are correlates of the Wunbye and Sitha formations of Shan State, Myanmar. The thick–bedded, quartz arenites of the Nyaungwiang Formation are faulted against the Ordovician carbonates and are probable lithological correlates of the Carboniferous Taungnyo Formation. The folds in the Lower Palaeozoic rocks are overturned to the northeast and deformation was in one major phase between the Tournaisian and the Early Permian. The Lower Palaeozoic strata may probably be followed as a ridge for at least 100?km towards the NNW, close to the western border of the Sibuma Block which is separated by a postulated cryptic suture from the Irrawaddy Block to the west. 相似文献
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Compared to earlier representatives of the family, pachycephalosaurids are less well known from upper Maastrichtian deposits around the world. Here, we report on a nearly complete left postorbital attributable to the pachycephalosaurid Sphaerotholus cf. Sphaerotholus buchholtzae from the upper Maastrichtian Frenchman Formation of Saskatchewan. This marks a probable northern range extension for the species into Canada, and the first occurrence of a pachycephalosaurid from this formation. We further demonstrate the taxonomic distinction between Stegoceras edmontonense and S. buchholtzae, which has been debated, based on postorbital sutural proportions. The northerly occurrence of Sphaerotholus cf. S. buchholtzae is consistent with the hypothesis of low beta diversity during the late Maastrichtian of North America, and its high stratigraphic incidence documents the persistence of non-pachycephalosaurin pachycephalosaurines in a critical interval for understanding the end-Cretaceous mass extinction event. 相似文献