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1.
The paper describes a Serpukhovian Stage section, exposed along the Ural River near the village of Verkhnyaya Kardailovka (Bashkortostan). The section is uniquely complete and is proposed as a GSSP candidate for the base of the Serpukhovian. The Upper Visean and Serpukhovian beds are represented by relatively deep facies, which contain ammonoids, conodonts, ostracods, foraminifers, and other fossils. The section is described bed-by-bed and subdivided into zones based on four faunal groups. The lower boundary of the Serpukhovian is placed at the base of the Lochriea ziegleri conodont zone. The stratigraphic units are correlated with synchronous beds of the East European Platform, the Donets Basin, Western Europe, Central Asia, and North America.  相似文献   

2.
The Upper Cretaceous La Cova limestones (southern Pyrenees, Spain) host a rich and diverse larger foraminiferal fauna, which represents the first diversification of K-strategists after the mass extinction at the Cenomanian–Turonian boundary.The stratigraphic distribution of the main taxa of larger foraminifera defines two assemblages. The first assemblage is characterised by the first appearance of lacazinids (Pseudolacazina loeblichi) and meandropsinids (Eofallotia simplex), by the large agglutinated Montsechiana montsechiensis, and by several species of complex rotalids (Rotorbinella campaniola, Iberorotalia reicheli, Orbitokhatina wondersmitti and Calcarinella schaubi). The second assemblage is defined by the appearance of Lacazina pyrenaica, Palandrosina taxyae and Martiguesia cyclamminiformis.A late Coniacian-early Santonian age was so far accepted for the La Cova limestones, based on indirect correlation with deep-water facies bearing planktic foraminifers of the Dicarinella concavata zone. Strontium isotope stratigraphy, based on many samples of pristine biotic calcite of rudists and ostreids, indicates that the La Cova limestones span from the early Coniacian to the early-middle Santonian boundary. The first assemblage of larger foraminifera appears very close to the early-middle Coniacian boundary and reaches its full diversity by the middle Coniacian. The originations defining the second assemblage are dated as earliest Santonian: they represent important bioevents to define the Coniacian-Santonian boundary in the shallow-water facies of the South Pyrenean province.By means of the calibration of strontium isotope stratigraphy to the Geological Time Scale, the larger foraminiferal assemblages of the La Cova limestones can be correlated to the standard biozonal scheme of ammonites, planktonic foraminifers and calcareous nannoplankton. This correlation is a first step toward a larger foraminifera standard biozonation for Upper Cretaceous carbonate platform facies.  相似文献   

3.
Devonian sediments of the Malaguide Complex potentially could include the Frasnian–Famennian boundary, one of the five greatest Phanerozoic biotic crises. Conodont biofacies and microfacies of carbonate clasts from a pebbly mudstone underlying Tournaisian radiolarites allows identification, for the first time in the Malaguide Complex, of Devonian shallow marine environments laterally grading to deeper realms. The clasts yielded Frasnian conodont associations of the falsiovalis to rhenana biozones, with six biofacies that reveal different environmental conditions in their source areas. Source sediments were dismantled and redeposited within the pebbly mudstone, whose origin is tentatively related to one of the events that are associated worldwide with the Frasnian–Famennian crisis. The latter is recorded, in two equivalent Malaguide pelagic successions, by stratigraphic discontinuities, and it was, probably, tectonically and/or eustatically controlled, as in other Alpine‐Mediterranean Paleotethyan margins.  相似文献   

4.
Among the smaller foraminifers from the Lower Permian of Western Tethys (Pamir, Northern Afghanistan, Central and Eastern Iran, Armenia, and Turkey), foraminiferal assemblages characteristic of the Asselian, Sakmarian, Yakhtashian, Bolorian, and Kubergandian stages are distinguished. The first stratigraphic scheme based on smaller foraminifers is elaborated for the Lower Permian (Cisuralian Series) of Western Tethys. Eight biostratigraphic units distinguished in the Lower Permian and one in the Kubergandian Stage are ranked as beds with characteristic foraminiferal assemblages. At particular stratigraphic levels, the beds are recognizable in different paleogeographic provinces of the Tethyan Realm, which enables correlation between deposits concurrently accumulated under dissimilar climatic and facies conditions to be carried. Some of the distinguished beds are recognizable beyond the Tethyan Realm, for instance in the Donetsk basin, Cis-Urals, Pechora coal basin, and Spitsbergen. Among foraminifers that have been studied, 264 species and subspecies, including 16 new taxa, are identified. The following species and subspecies are identified and described for the first time: Hemigordius permicus beitepicus subsp. nov., H. pamiricus sp. nov., Neohemigordius afganicus sp. nov., N. carnicus sp. nov., N. bangi sp. nov., N. zulumarticus sp. nov., N. kubergandinicus sp. nov., Geinitzina grandella sp. nov., G. dentiformis sp. nov., G. bella sp. nov., Pachyphloia paraovata minima sp. nov., P. aucta sp. nov., Frondicularia porrecta sp. nov., Globivalvulina gigantea sp. nov., G. compacta sp. nov., and G. explicata sp. nov.  相似文献   

5.
The Wangchengpo Frasnian section of Dushan County contains two atrypid brachiopod assemblages. The lower is characterized by the Atryparia (Costatrypa) dushanensis fauna that appears at the base of the Hejiazhai Member approximately in the falsiovalis to transitans conodont zones: the upper is characterized by the Radiatrypa yangi fauna, which appears in the Lujiazhai Member approximately correspondent with the hassi to Upper rhenana conodont zones. Atrypid brachiopods, together with other brachiopods from the Dushan section show that the Hejiazhai Member is of Frasnian age. Preliminary analyses of Frasnian atrypid brachiopods from sections of South China indicate that there are nine genera and subgenera including Atryparia (Costatrypa), Kyrtatrypa, Spinatrypa, lsospinatrypa, Spinatrypina, lowatrypa, Desquamatia (Desquamatia). Desquamatia (Seratrypa), and Radiatr)pa. Atrypid species diversity did not change much through the Frasnian. On a regional scale in South China, most atrypid species went extinct prior to the Frasnian/Famennian boundary. At any specific locality or section, these atrypids became extinct about 20-40 m below the Frasnian/Famennian (F/F) boundary, within the linguiformis conodont Zone, marking this as the major extinction level. Three new atrypid species are described: Atryparia (Costatrypa) dushanensis, lowatrypa pseudobodini, and Radiatrypa yangi.  相似文献   

6.
A down-core record of stable isotope and geochemical results is integrated with palynofacies (kerogen) data from the New Albany Shale (Indiana) to reconstruct environmental changes that occurred across the Frasnian–Famennian boundary. Preliminary interpretations are focused on developing several multiproxy linkages that will potentially lead toward a more robust understanding of the occurrence and significance of phytoplankton assemblage variations during the Late Devonian, a time of widespread black shale formation. Development of such linkages will potentially provide a more comprehensive assessment of the various controls on 1) primary production, and 2) carbon sequestration in a large, low-paleolatitude intracratonic basin.An abrupt change in the geochemical and biotic proxies for particulate organic matter across the Frasnian–Famennian boundary coincides with a distinct lithological change, characterized by laminated, brownish-black Famennian mudstones unconformably overlying alternating bioturbated, greenish-gray and non-bioturbated, dark-gray Frasnian mudstones. Elemental and isotopic profiles reflect different patterns of production, degradation, and removal of organic carbon in the two shale facies. A shift from acritarch- to prasinophyte-dominated waters across the boundary indicates the overall importance of bathymetric fluctuations, chemico-physical conditions, and nutrient availability related to eustatic sea-level change. A positive δ13CV-PDB shift of 1.1‰ across the boundary is interpreted to be correlative with the global Upper Kellwasser Event. A preliminary model is proposed to explain the sustainable primary production during times of maximum flooding, thereby enhancing organic preservation during black shale formation.  相似文献   

7.
The composition of stable carbon and oxygen isotopes in the section of an isolated carbonate platform is analyzed. Traces of several global and subglobal transgressions and regressions have been found in the limestone strata. Some of these phenomena were associated with the Upper Kellwasser (at the Frasnian–Famennian boundary) and multiphase Hangenberg (at the Devonian–Carboniferous boundary) Events. Nevertheless, there were no considerable sea level fluctuations in the platform water area. There is no evidence for subaerial erosion. The bottom water during sedimentation was mostly in oxic conditions.  相似文献   

8.
Integrative methods of chemostratigraphy and biostratigraphy were used in the study of microtektites and moderate nickel-iridium anomaly beds in the Devonian-Carboniferous boundary beds at Huangmao (Guangxi Autonomous Region) and Muhua (Guizhou Province) in southern China. Microtektites provide evidence for meteoritic impact event(s), whereas the minerals and the chemical composition of the Ni-Ir anomaly beds likely display a submarine hydrothermal origin. It is postulated that the intensification of the rifting-hydrothermal process, and the ensuing pollution, might have been responsible for the Devonian-Carboniferous biotic crisis. This process began in the late Famennian expansa zone, lasted to the Tournaisian duplicata zone, and produced the largest manganese ore deposits of China.  相似文献   

9.
The base of the Saerba Member (Mbr) of the Hongguleleng Formation (Fm.) probably lies in the Famennian Palmatolepis crepida Zone; the Longkou Mbr is probably a sedimentary wedge that thins out northwards; the Duguer Mbr has an approximate age from the upper part of the Pa. marginifera Zone or the Lower Pa. rugosa trachytera Zone through the top of the Pa. perlobata postera Zone; the Wulan Mbr has an age approximately corresponding to the whole Pa. gracilis expansa Zone. In the Bulongguoer section, the Lower Mbr of the Hongguleleng Fm. corresponds to Famennian Pa. crepida Zone through Pa. marginifera Zone; the Middle Mbr probably ranges from the Pa. r. trachytera Zone through the Pa. g. expansa Zone. The basal Namu Mbr of the Heishantou Fm. is probably the product during and after the Hangenberg Event in the upper part of the Siphonodella praesulcata Zone, which is still within the Devonian. In this context, the underlying Chasi Mbr may approximately correspond to the lower part of the S. praesulcata Zone (before the Hangenberg Event). Lateral distribution of strata indicates that the Upper Devonian in the Gennaren and Saerba areas each constitutes a structure of syncline, which differs from the previous recognition of a monocline structure.  相似文献   

10.
To improve regional and intercontinental correlation of the uppermost Devonian–lowermost Carboniferous, we examined the conodont faunas and carbon isotopic records of the Tangbagou Formation in the Qilinzhai section, southern Guizhou, South China. The Tangbagou Formation is a succession of mixed carbonate–siliciclastic rocks that accumulated on a shallow‐water platform under normal marine conditions. Seven conodont zones for shallow‐water biofacies in South China, the Cl. gilwernensis–Cl. unicornis Zone, the Po. spicatus Zone, the Si. homosimplex Zone, the Si. sinensis Zone, the Si. eurylobata Zone, the Ps. multistriatus Zone and the Po. co. porcatus Zone in ascending order, are recognized in the Tangbagou Formation. Although apparently limited in its value for global correlation, this conodont zonation is more applicable to shallow‐water biofacies in South China. Carbonate samples have yielded carbon isotopic signatures consistent with those recorded in Euroamerica sections, in particular showing four distinct characteristics: (1) the peak values of Hangenberg Carbon Isotope Excursion (HICE) during the latest Devonian, (2) a minor positive shift (P1) in the Si. homosimplex Zone during the early Tournaisian, (3) a second minor positive shift (P2) in the Si. sinensis Zone and (4) the middle Tournaisian Carbon Isotope Excursion (TICE) in the middle part of the Tangbagou Formation. The similarity in peak values (~5.5‰) and magnitude of TICE for the Qilinzhai and Belgian sections indicates that the Euro‐asia δ13Ccarb trends may reflect the changes in global mean ocean δ13CDIC, rather than having been overprinted by local carbon cycling. Integration of conodont biostratigraphy and δ13C stratigraphy provides a powerful tool for stratigraphic correlation. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

11.
《Gondwana Research》2015,27(3-4):1159-1172
Carboniferous conodonts are reported for the first time from Myanmar (Burma). Conodont faunas representative of the Scaliognathus anchoralis and Gnathodus typicusProtognathodus cordiformis conodont zones date the sampled Taungnyo Group south of Loi Kaw, Kayah State as late Tournaisian confirming a Mississippian (Lower Carboniferous) age for the sampled part of this stratigraphic unit. The dated strata are stratigraphically just below the Tournaisian–Visean (T-V) boundary. Tournaisian strata are thus for the first time unequivocally demonstrated in the Shan Plateau region of Myanmar. Similar conodont faunas from the T-V boundary interval in SE Asia indicate a complete stratigraphic sequence at this level in shallow-marine sequences on intra-Tethyan Cathaysian tectonic blocks (South China) and in deep-marine Palaeo-Tethyan sediments (cherts of the Inthanon suture zone, Thailand). However, in shallow-marine sequences on the Sibumasu Block, located on the NE margin of Gondwana in the Carboniferous, they demonstrate a non-sequence or unconformity at this level, also seen elsewhere in Gondwana. Biogeographic links between upper Tournaisian and early Visean conodonts on the Sibumasu Terrane and Laurentia and Eastern Australian Gondwana support a NW Australian Gondwana margin position for Sibumasu in the Late Palaeozoic.  相似文献   

12.
Abstract: The Caiziyan Middle and Upper Devonian boundary section is located approximately 30 km northeast of Guilin. It hosts relatively abundant benthic and common–rare pelagic fossils, including brachiopods, corals, tentaculites, and conodonts, which may serve as a better suitable section for pelagic and neritic stratigraphic correlation. In this section, 10 “standard” conodont zones are recognized across the Givetian–Frasnian boundary, including, in descending order, the Lower hassi Zone, punctata Zone, transitans Zone, the Upper falsiovalis Zone, the Lower falsiovalis Zone, disparilis Zone, the Upper hermanni–cristatus Zone, the Lower hermanni–cristatus Zone, the Upper varcus Zone, and the Middle varcus Zone, all of which are defined by the first occurrence of their defining conodont species. The Middle–Upper Devonian (Givetian–Frasnian) boundary is defined by the first occurrence of Ancyrodella pristina in accordance with the Global Stratotype Section and Point (GSSP), which is assigned at 6.2m above the base of bed 19 in the Caiziyan section.  相似文献   

13.
韩迎建 《地球学报》1987,9(3):171-197
笔者在广西象州中坪马鞍山剖面上泥盆统“融县组”中部,首次发现了地层连续、岩性均一、牙形石带齐全的弗拉斯阶/法门阶界线层。这一界线层完全符合国际泥盆纪地层分会(SDS 1983)作出的关于划分弗拉斯阶/法门阶界线条件的决议。并与被誉为盆地相最佳剖面的西德Schmidt剖面(SDS Newsl.1986,no.1,Doc.C)的牙形石序列基本一致。无论是从岩石的均一性或是牙形石生物的连续性上,马鞍山剖面完全可与西德Schmidt剖面媲美,它是目前国内研究弗拉斯阶/法门阶界线的理想剖面之一。本文除了对这一界线进  相似文献   

14.
Traditionally, the lower boundary of the Aikuanian(Yanguanian) Stage has always been considered as the lower boundary of the Carboniferous in China. marked by the occurrence of the coral Cystophrentis.In recent years, some biostratigraphical research results have shown that the Cystophrentis zone is only distributed in the lower part of the Menggong'ao Formation(or the Gelaohe Formation) and that there is an interval zone namely the Cystophrentis-Pseudouralinia interval zone, wedged in just between the Cystophrertis zone and the Pseudouralinia zone in the upper part of the Menggong'ao Formation(or the GelaoheFormation). According to the current study of the conodont biostratigraphy, the coral Cystophrentis zone appears to be of latest Devonian age. So the lower boundary of the Aikuanian Stage is much lower than the lower Devonian-Carboniferous boundary and should no longer be regarded as the lower boundary of the Carboniferous in China. In this paper, two proposals for the Devonian-Carboniferous boundary in the shallow-water facies areas of China are put forward: 1) that the boundary is marked by the first appearance of the conodont Siphonodella(Eosiphonodella) simplex, and 2) that the boundary is recognized by the extinction of the coral Cystophrentis or the brachiopod Tenticospirifer.In addition, 4 species are newly estabished here: Icriodus obovatus sp. nov., Polygnathus lepidus sp. nov., Polygnathus paucidentatus sp. nov. and Polylophodonta jianghuaensis sp. nov.  相似文献   

15.
Sedimentary petrology and trace element geochemistry indicate that the Late Devonian to Early Carboniferous Heishantou Formation near Boulongour Reservoir (NW Xinjiang, China) was deposited on a steep slope, mid-latitude accreting island arc complex in an open oceanic system. Bulk 87Sr/86Sr ratios show excursion patterns that are consistent with excursions at the Devonian–Carboniferous (D–C) boundary in epicontinental margin sediments. Sedimentation rates for the Boulongour Reservoir sediments show highly variable rates that range from 0.5 cm/ky to 10 cm/ky, consistent with other Late Devonian sections and modern arc environments. Multiple whole rock geochemical proxies for anoxia and the size and distribution of pyrite framboids suggest the presence of the Hangenberg Event in the sediments associated with the D–C boundary, despite the lack of visible black shale. The presence of anoxia in an open ocean, island arc environment cannot be explained by upwelling of anoxic bottom waters at this paleolatitude, but can be explained by the global infliction of oceanic shallow water eutrophication on to a climate system in distress.  相似文献   

16.
季强 《地球学报》1991,12(2):115-127
在地质历史时期,特别是在显生代,生物的演化发展十分迅速,因而生物的发生和衰亡是客观存在的。然而,能被人们认识为地质事件的巨大生物绝灭却是稀少的,它们的性质和起因也不尽相同。本文研究的弗拉斯—法门事件就是其中一次比较明显的巨大生物绝灭事件。我国泥盆纪地层发育良好,沉积类型齐全,化石十分丰富,极有利于弗拉斯—法门期生物绝灭事件的研究。本文本着实事求是的精神,从不同的角度观察和阐述这一事件在时间和空间上的表现方式和特征,进而探讨这一事件的性质和起因。  相似文献   

17.
Calcareous foraminifers representing 9 species and 5 genera were investigated in two Famennian sections located in the south‐western part of the Holy Cross Mountains (HCM), central Poland. They constitute redeposited material that, together with crinoids and calcareous algae, comprise the dominant component of limestone turbidite beds intercalated with deep‐marine marly sediments. The calcareous material was redeposited from an unknown carbonate platform located probably to the south of the HCM area. The first appearance data of foraminifers, mainly from the quasiendothyrid group, correlated to the Standard Conodont Zonation, indicate a diachronous appearance of the same species in different parts of Europe due to a migration delay from the foraminiferal evolutionary centre located in the south‐eastern shelves of Laurussia in the neighbouring areas. As a result, the Moravian foraminiferal zonation, where index taxa appeared in similar stratigraphic intervals, was chosen as the most applicable to the stratigraphy in the central Polish area. The Quasiendothyra communis–Eonodosaria evlanensis Interzone, the Quasiendothyra communis–Quasiendothyra regularis Zone and Quasiendothyra kobeitusana–Quasiendothyra konensis Zone were distinguished, respectively, in the HCM sections. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

18.
Precise U–Pb zircon dates from three volcanic ash beds that bracket the Hangenberg Shale in the Holy Cross Mountains, Poland, constrain the age and duration of one of the most significant palaeobiological events of the Palaeozoic Era, the Hangenberg Event. It is linked to a terminal Devonian global shift from greenhouse to icehouse climate conditions, a global transgression, and widespread black shale deposition. Our results constrain the Hangenberg Event to between 358.97 ± 0.11 Ma and 358.89 ± 0.20 Ma, with a calculated duration of 0.05 +0.14/?0.05 Ma. A third, underlying ash bed yielded a distinctly older age of 359.97 ± 0.46 Ma. The duration of ~50–100 ka. for the event is comparable to those of Quaternary glaciations, and is consistent with both a glacio‐eustatic origin for the eustatic fluctuations and changes in ocean chemistry that led to this major reorganization of the biosphere.  相似文献   

19.
华南上泥盆统和下石炭统层序地层学   总被引:9,自引:0,他引:9  
王训练  李世隆  王约 《地球学报》1997,18(1):98-105
本文把华南法门阶上部和杜内阶分为4个层序,自下而上依次命名为SQ0、SQ1、SQ2和SQ3。其中SQ0属斯图年阶(Strunian)(泥盆系最顶部),其余3个层序归杜内阶。这4个层序可以与欧美等地同期的层序进行对比,表明当时的海平面升降变化及其由此而产生的沉积层序具有全球的一致性。层序地层学、生物地层学和事件地层学综合研究表明,华南浅海相区与Siphonodelapraesulcata-S.sulcata界线一致的泥盆-石炭系界线不仅高于Cystophrentis带顶界,而且还应高于引起Cystophrentis绝灭的海退事件层的顶界。因此建议以Cystophrentis-Pseudouralina间隔带中最明显的一个海进面,即SQ1的海进体系域的底界作为华南浅海相区泥盆-石炭系界线。这条界线与泥盆-石炭纪之交海退事件层的顶界正好一致,大致相当于Pseudouralina组合带底部。  相似文献   

20.
Limestones in the Palmers Oakey District, N.S.W., range in age from Middle Silurian to Early Devonian. They occur as sheet‐like, bioclastic beds and/or isolated clasts in three facies: a volcaniclastic facies, a mudstone‐limestone facies, and a limestone‐mudstone breccia facies. Multielement conodont taxa, not previously reported from Australia, include Kockelella absidata, Kockelella stauros, Ozarkodina asymmetrica, Ozarkodina stygia, Ozarkodina transitans, Pseudooneotodus bicornis, and Pseudooneotodus tricornis.  相似文献   

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