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1.
Sediments of Early Aptian age in Bulgaria can be assigned to four different facies: platform carbonates (Urgonian complex), shallow-water siliciclastics, hemipelagic and flyschoid siliciclastics. The taxonomic analysis of the ammonite faunas of 18 sections from these four different facies resulted in a revision of the existing ammonite zonation scheme so far applied in Bulgaria and adjoining areas. A new biostratigraphic scheme, which bridges the western and eastern Tethys, is thereby proposed for the Lower Aptian of Bulgaria.The Upper Barremian Martelites sarasini Zone is characterized in its upper part by the Pseudocrioceras waagenoides Subzone in the shallow-water sections and by a horizon with Turkmeniceras turkmenicum in the deep-water settings. The Upper Barremian/Lower Aptian boundary is fixed by the first appearance of Paradeshayesites oglanlensis. For the Lower Aptian the following ammonite zones were established (from bottom to top): The Paradeshayesites oglanlensis Zone, the Deshayesites forbesi Zone (= formerly Paradeshayesites weissi Zone) including the Roloboceras hambrovi Subzone in the upper part, the Deshayesites deshayesi Zone including the Paradeshayesites grandis Subzone in the upper part and the Dufrenoyia furcata Zone. The Lower–Middle Aptian boundary has been defined by the appearance of species belonging to the genera Epicheloniceras and Colombiceras.The Lower Aptian ammonite faunas of Bulgaria, allow an interregional correlation with other areas of the Tethyan Realm. The presence of Turkmeniceras in the Upper Barremian enables a correlation with the Transcaspian region, whereas Roloboceras, Koeneniceras and Volgoceratoides found in the middle part of the Lower Aptian are more typical representatives of the ammonite faunas in northern Europe (England, Germany, Volga region).The analysis of the ammonite successions in combination with sedimentological observations enable us to conclude that the marls and marly limestones of the Lower Aptian studied here also cover the interval of the Oceanic Anoxic Event 1a. An interval of thin-laminated clays, rich in organic matter, was identified in the upper part of the D. forbesi Zone (Roloboceras hambrovi Subzone). This interval is characterized by a total lack of benthic faunas.  相似文献   

2.
The stratigraphic distribution of ammonoids was analyzed in the Daxatina canadensis Subzone of the Trachyceras Zone distinguished in the Dolomites of Italy. It was established that ammonoids of the Daxatina and Trachyceras genera are confined to the lower and upper parts of the canadensis Subzone in the Stuores-Wiesen section, which was suggested as a global stratigraphic section of the lower boundary of the Carnian Stage. Owing to discreteness of the ammonoid complex and absence of the Trachyceras genus, the lower part of the canadensis Subzone was excluded from the Trachyceras generic zone and is considered as the independent Daxatina canadensis Zone, which overlies the Frankites regoledanus Zone. On the basis of the principle of priority and similar ammonoids of the canadensis and regoledanus zones, the lower boundary of the Carnian Stage was accepted in the basement of the Alpine Trachyceras aon Zone and coincides with appearance of the Trachyceras genus. The main problems of the Boreal-Tethyan correlation of the Lower Carnian and adjacent stratigraphic levels are reviewed. The composition and distribution of the Lower Carnian ammonoids of northeastern Asia are specified taking into account the results of the revision of the Early Carnian trachyceratids of this region. Being the traditional biomarkers of the basal beds of the Carnian Stage in the Tethys, the ammonoids of the Trachyceras genus, which were unknown before in the Boreal Realm, were identified for the first time in the Lower Carnian of northeastern Asia. The Lower Carnian rocks of northeastern Asia, British Columbia, and the Alps were zonally correlated and the Lower Carnian boundaries were substantiated in the Boreal Realm. The Boreotrachyceras omkutchanicum Zone correlates with the Alpine Trachyceras aon Zone by the presence of the Trachyceras genus and stratigraphic position over the Stolleyites tenuis Zone and its analogs in British Columbia. The ammonoid complex of the Neosirennites armiger Zone includes Sirenites s.s., in particular, Sirenites ovinus Tozer species, known in the upper zone of the Lower Carnian of British Columbia (Sirenites nanseni), which allows comparison of the armiger and nanseni zones and, through it, with the upper part of the Alpine Austrotrachyceras austriacum Zone.  相似文献   

3.
根据辽东半岛上寒武统长山阶三叶虫的纵向分布和演化序列,划分了6个生物带和2个亚带,其中新建立生物带2个.并与国内外进行了对比.长山期三叶虫包括80个种,分属50个属或亚属.由于篇幅所限,本文仅描述部分新种,地层剖面从略.  相似文献   

4.
The genera Titanites and Glaucolithites, which were previously known only from the Portlandian of Northwestern Europe are now established in Epivirgatites nikitini Zone of European Russia. The Volgian species of Titanites are represented by both the endemic taxa Titanites (Paratitanites) manipulocostatus subgen. et sp. nov. and T. (Pseudogalbanites) triceps subgen. et sp. nov. and Titanites (Titanites) ex gr. titan Buckman of the Portland type. A new species Glaucolithites gardarikensis is described. It is likely that these ammonites migrated to the Central Russian Sea from northwestern Europe via the Norway-Greenland seaway and further to the Mezen-Pechora system of straits, which is supported by occurrences of Titanites in the north of Central Russia and Glaucolithites in East Greenland and on Spitsbergen. The direct and indirect correlations show that the middle part of the Nikitini Zone (Lahuseni Subzone) should at least partly be correlated with the Portlandian Kerbeus Zone.  相似文献   

5.
Biostratigraphy of the Berriasian Stage in the Crimean Mountains is specified and substantiated. Fragments of all the standard stage zones (jacobi, occitanica, and boissieri) are distinguished based on the found index species, and position of the Jurassic-Cretaceous boundary is targeted. According to verified distribution of ammonites, the jacobi Zone is divided into the jacobi and grandis subzones crowned by the Malbosiceras chaperi Beds. The Tirnovella occitanica-Retowskiceras retowskyi Beds and overlying Dalmasiceras tauricum Subzone are recognized in deposits of the occitanica Zone. The upward succession of biostratigraphic units established in the boissieri Zone includes the Euthymiceras-Neocosmoceras Beds, Riasanites crassicostatus Subzone, Symphythyris arguinensis and Jabronella sf. paquieri-Berriasella callisto Beds. The last biostratigraphic unit is suggested in this work instead the former Zeillerina baksanensis Beds. Except for the jacobi Zone, the substantiated ammonoid zonation is practically identical to the Berriasian biostratigraphic scale of the northern Caucasus, although the Berriasian-Valanginian boundary has not been defined in the Crimean Mountains based on ammonites. Several marker levels of bivalve mollusks and four biostratigraphic subdivisions of brachiopod scale are distinguishable here. As for the latter, these are (from the base upward) the Tonasirhynchia janini, Belbekella airgulensis-Sellithyris uniplicata, Symphythyris arguinensis, and Zeillerina baksanensis beds.  相似文献   

6.
This paper contains the results of a comprehensive study of the standard Rarecostites subarietis Subzone of the upper Bajocian Parkinsonia parkinsoni Zone in sections on the Kyafar River (a tributary of the Bolshoi Zelenchuk River, Karachay-Cherkessia, Russia). The subzone is represented by shales with marl interbeds and sideritic concretions of the upper member of the Djangura Formation. The taxonomic composition and distribution of ammonites, foraminifers, ostracodes, dinoflagellate cysts, and miospores are established. The characteristic assemblages recognized of microfauna and palynomorphs enabled the recognition of foraminiferal and dinocyst biostratigraphic units for this Middle Jurassic interval. The index fossils are illustrated.  相似文献   

7.
The fossil snakefly family Baissopteridae from the Lower Cretaceous (upper Barremian) of the Yixian Formation of Liaoning Province, China is reviewed. Two genera and five species of Baissopteridae are recorded, including a new genus, namely Microbaissoptera gen. nov., and three new species, i.e., Baissoptera bicolor sp. nov., Baissoptera sinica sp. nov., and Microbaissoptera monosticha sp. nov. Moreover, Baissoptera euneura Ren, 1997 is herein treated as a new junior synonymy of Baissoptera grandis Ren in Ren et al., 1995. Baissoptera minima Ponomarenko, 1993 is transferred to the presently described new genus Microbaissoptera gen. nov. based on the small body-size and the presence of a single gradate series of crossveins in radial and medial areas of posterior part of both fore- and hind wings. A key to genera of Baissopteridae is provided.  相似文献   

8.
A representative early Bajocian belemnite assemblage containing four genera and 11 species (two identified in open nomenclature and five new: Eocylindroteuthis weisi sp. nov., E. mariottii sp. nov., E. yarkovi sp. nov., Homaloteuthis volgogradensis sp. nov., and Hastites orphana sp. nov.) is described from a section near the Dubovoi hamlet in the Greater Don Bend area (southern termination of the Don-Medveditsa dislocations). Some members of this assemblage were previously known from the Caucasus; however, it is possible to state the discovery of a Euroboreal belemnite fauna completely new for Russia, previously described only from Central Europe and almost unknown for Eastern Europe. The age of the studied assemblage collected from the lower part of the section, traditionally considered to be Upper Bajocian, corresponds to the Laeviuscula ammonite Chronozone and is the first reliable evidence of marine settings in the Volga Region for the early Bajocian. Two new biostratigraphic units, Beds with Eocylindroteuthis weisi and Beds with H. orphana, are introduced. The former, judging from the occurrences of its characteristic species in Western Europe, has a broad correlative potential. On the basis of datings obtained, the scheme of the formational subdivision of the Middle Jurassic of the Volga Region near Volgograd is revised, and the formerly abandoned Bakhtemir Formation is reinstated as a valid unit. Its total range is reestablished as corresponding to the upper part of the Discites (?)/Laeviuscula Chronozone (lower Bajocian)–Garantiana Chronozone (upper Bajocian).  相似文献   

9.
The Dvuyakornaya Formation section in the eastern Crimea is described and subdivided into biostratigraphic units based on ammonites, foraminifers, and ostracodes. The lower part of the formation contains first discovered ammonites of the upper Kimmeridgian (Lingulaticears cf. procurvum (Ziegler), Pseudowaagenia gemmellariana Olóriz, Euvirgalithacoceras cf. tantalus (Herbich), Subplanites sp.) and Tithonian (?(Lingulaticeras efimovi (Rogov), Phylloceras consaguineum Gemmellaro, Oloriziceras cf. schneidi Tavera, and Paraulacosphinctes cf. transitorius (Oppel)). Based on the assemblage of characteristic ammonite species, the upper part of the formation is attributed to the Berriasian Jacobi Zone. Five biostratigraphic units (zones and beds with fauna) distinguished based on foraminifers are the Epistomina ventriosa-Melathrokerion eospirialis Beds and Anchispirocyclina lusitanica-Melathrokerion spirialis Zone in the upper Kimmeridgian-Tithonian, the Protopeneroplis ultragranulatus-Siphoninella antiqua, Frondicularia cuspidiata-Saracenaria inflanta zones, and Textularia crimica Beds in the Berriasian. The Cyrherelloidea tortuosa-Palaeocytheridea grossi Beds of the Upper Jurassic and Raymoorea peculiaris-Eucytherura ardescae-Protocythere revili Beds of the Berriasian are defined based on ostracodes. A new biostratigraphic scale is proposed for the upper Kimmeridgian-Berriasian of the eastern Crimea. The Dvyyakornaya Formation sediments are considered as deepwater facies accumulated on the continental slope.  相似文献   

10.
This study of the upper Maastrichtian to Danian sedimentary succession from the northern part of the Romanian Eastern Carpathians (Varniţa section) aims to establish an integrated biostratigraphy based on calcareous nannofossils, organic-walled dinoflagellate cysts (dinocysts) and foraminiferal assemblages, and to reconstruct the depositional environments of the interval. The stratigraphic record across the studied section is incomplete, considering that an approximately 16 m thick strata interval from the top of the Maastrichtian to lowermost Danian cannot be analyzed due to a landslide covering the outcrop. The upper Maastrichtian is marked by a succession of biostratigraphic events, such as the First Appearance Datum (FAD) of the nannoplankton taxon Nephrolithus frequens and FAD of the dinocyst species Deflandrea galeata and Disphaerogena carposphaeropsis, and the Last Appearance Datum (LAD) of Isabelidinium cooksoniae in the lower part of the section. These bioevents are followed by the LAD of the Dinogymnium spp. and Palynodinium grallator dinocyst markers in the top of the Maastrichtian deposits analyzed. In terms of foraminiferal biostratigraphy, the upper Maastrichtian Abathomphalus mayaroensis Zone is documented in the lower part of the studied section. Some bioevents, such as the bloom of the calcareous dinoflagellate genus Thoracosphaera and the FAD of the organic-walled dinocysts Damassadinium californicum, Senoniasphaera inornata, Xenicodinium lubricum and X. reticulatum suggest an early Danian age for the middle part of the section. From the Danian deposits in the Varniţa section, we describe a new organic-walled dinocyst species, Pentadinium darmirae sp. nov., which is until now the only species of the Pentadinium genus discovered in the Paleocene. The occurrence of the global Danian dinocyst marker Senoniasphaera inornata in the top of the section, suggests an age not younger than middle Danian (62.6 Ma) for the analyzed deposits.The palynofacies constituents, as well as the agglutinated foraminiferal morphogroups, used to reconstruct the depositional environments, show that the late Maastrichtian sediments were deposited in an outer shelf to distal (bathyal) environment, followed by a marine transgression during the Danian.  相似文献   

11.
Ostracod from the upper Lower to Middle Devonian rocks of the Argentine Precordillera Basin (Talacasto and Punta Negra formations) are studied. One new genus Pircawayra nov. gen., and five species (including three new: Pircawayra gigantea nov. gen. and sp., Lapazites trinodis nov. sp. and Keslingiella? teresae nov. sp.) are defined. The recorded ostracod fauna closely resembles that coeval from Bolivia and South Africa, exhibiting a remarkable endemism, not only at the genus level, but also at the species level. In addition to its low-diversity, the Malvinokaffric ostracod association is also characterized by having large, thick, coarsely ornamented and swollen valves. The similar ostracod composition from the Andean and South African basins suggests faunal exchange between these two areas. Based on the ostracod faunas, the Malvinokaffric Realm is clearly recognizable at least up to the Middle Devonian.  相似文献   

12.
The oldest bradoriid fauna from Australia, occurring in the lower Cambrian Ajax and Wirrapowie limestones of the Flinders Ranges, South Australia consists of eleven taxa, including one new genus and species, Quadricona madonnae gen. et sp. nov. and two new species, Liangshanella circumbolina sp. nov. and Zepaera jagoi sp. nov. In the Ajax Limestone, Liangshanella circumbolina sp. nov. occurs c. 20 m below the FAD of the zonal trilobite Abadiella huoi. This pre-trilobitic occurrence represents the oldest bivalved arthropod hitherto known from East Gondwana and suggests a lower Cambrian (Series 2, Stage 3) age for the assemblage. The recognition of distinct bradoriid assemblages associated with the Abadiella huoi (Atdabanian), Pararaia tatei, P. bunyerooensis and P. janeae (all Botoman) trilobite biozones in South Australia indicates great potential for future regional biostratigraphic correlation. Quantitative biogeographic analysis including new taxonomic data from the lower Cambrian of South Australia, highlights the strong endemism displayed by early Cambrian bradoriid communities and strengthens the close faunal affinities with South China and Antarctica.  相似文献   

13.
The microbiota of the upper Viséan (Asbian–Brigantian) rocks in the Lough Allen Basin in northwest Ireland is analysed. The Middle Mississippian sequence studied extends from the upper part of the Dartry Limestone/Bricklieve Limestone formations of the Tyrone Group to the Carraun Shale Formation of the Leitrim Group. The rocks have been traditionally dated by ammonoid faunas representing the B2a to P2c subzones. The Meenymore Formation (base of the Leitrim Group) also contains conodont faunas of the informal partial‐range Mestognathus bipluti zone. The upper Brigantian Lochriea nodosa Conodont Zone was recognized by previous authors in the middle of the Carraun Shale Formation (Ardvarney Limestone Member), where it coincides with upper Brigantian ammonoids of the Lusitanoceras granosus Subzone (P2a). Foraminifera and algae in the top of the Dartry Limestone Formation are assigned to the upper Cf6γ Foraminifera Subzone (highest Asbian), whereas those in the Meenymore Formation belong to the lower Cf6δ Foraminifera Subzone (lower Brigantian). The Dartry Limestone Formation–Meenymore Formation boundary is thus correlated with the Asbian–Brigantian boundary in northwest Ireland. For the first time, based on new data, a correlation between the ammonoid, miospore, foraminiferan and conodont zonal schemes is demonstrated. The foraminiferans and algae, conodonts and ammonoids are compared with those from other basins in Ireland, northern England, and the German Rhenish Massif. Historically, the Asbian–Brigantian boundary has been correlated with several levels within the P1a Ammonoid Subzone. However, the new integrated biostratigraphical data indicate that the Asbian–Brigantian boundary in northwest Ireland is probably located within the B2a Ammonoid Subzone and the NM Miospore Zone, but the scarcity of ammonoids in the Tyrone Group precludes an accurate placement of that boundary within this subzone. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

14.
Belemnites from the lower Bathonian of the Russian Plate are revised on the basis of the study of two reference sections—Pletnyovka and Sokur quarries. The first part of the study deals with the members of the family Megateuthididae. They include eight species of the genus Barskovisella gen. nov., neoendemic to the territory of the Russian Plate and originating from high Boreal taxa—species of the genus Paramegateuthis Gustomesov, 1960, which immigrated to the Middle Russian Sea in the early Bathonian via a short-lived meridional strait. The new genus includes six new species described in the present paper—Barskovisella pseudoishmensis sp. nov., B. issae sp. nov., B. variabilis sp. nov., B. barskovi sp. nov., B. gracilis sp. nov., and B. renegata sp. nov. The beds with Barskovisella, a new belemnite-based unit, corresponding to the Oraniceras besnosovi ammonite zone and including four successive phylogenetic biohorizons well comparable in resolution with ammonite-based infrazonal subdivisions, are introduced.  相似文献   

15.
Three new caddisflies species are described and illustrated from the mid-Cretaceous Burmese amber: Wormaldia cretacea sp. nov., W. resina sp. nov. (Philopotamidae) and Neureclipsis burmanica sp. nov. (Polycentropodidae). Palerasnitsynus ohlhoffi (Psychomyiidae) is re-described based on new fossils. Wormaldia are common in Burmese amber, and its diversity shows that this genus had very ancient origin and diversified at least during the mid-Cretaceous. N. burmanica sp. nov. is the oldest record of Neureclipsis, revealing this genus originated at least in the mid-Cretaceous. So far, six extinct species representing the small Order Trichoptera have been found in Burmese amber.  相似文献   

16.
A new non-marine ostracod Mongolocypris kohi sp. nov. is described from the upper Lower Cretaceous Jinju Formation of the Gyeongsang Basin, South Korea. This new species was described as Cypridea (Pseudocypridina) spp. by previous authors, but the typical rostrum shape, inconspicuous alveolar notch, the lack of alveolar ridge and the elongate limen are features that this species has in common with the genus Mongolocypris Szczechura, 1978. M. kohi sp. nov. is characterized by a reduced rostrum, the presence of a faint alveolar furrow and a slightly curved limen. This new species is considered an ‘early form’ of the genus Mongolocypris by its reduced rostrum and the faint alveolar furrow.  相似文献   

17.
Ammonite Fauriella boissieri (Pictet), the index species of the Berriasian upper zone, is described for the first time as taxon occurring in the Crimean Mountains. In the Berriasian sections of the central Crimea and Chatyr-Dag massif, species F. boissieri are encountered only in association with upper Berriasian ammonites. The Berriasian-Valanginian boundary has not been identified based on ammonites in the Crimean Mountains. Consequently, there is no reason to include the otopeta Zone into the boissieri Zone in the rank of its upper subzone.  相似文献   

18.
A new species of Offneria (Caprinidae) Offneria prebetica nov. sp., is described from the Murcia region (Prebetic zone, SE Spain). Its type level is the upper Bedoulian. The key diagnostic character of the new species is the presence on the ventral side of the left valve of an inner row, or double row, of polygonal canals flanked by outer piriform canals with one or two orders of bifurcations. Offneria prebetica nov. sp. is the most advanced species of the genus. Cluster analysis shows the placement of the new species in the monophyletic group of European species, in agreement with its geographic location. Offneria appears to be the most prolific genus of the Caprinidae with species having contrasting ages and palaeobiogeographic distributions. Stratigraphic data from SE Spain indicate that the Offneria lineage was resilient to the environmental perturbations recorded during the late Bedoulian, Offneria prebetica nov. sp. may be used as a time marker for this interval, and its last occurrence was coeval with the “Mid-Aptian extinction event”.  相似文献   

19.
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   

20.
Three previously described species and two new species of rhaxellid microscleres, Rhaxella winspitensis sp. nov. and R. elongata sp. nov., are described from cherts collected from the Cherty Series of the Portlandian of Dorset. The classification of Rhaxella is reviewed, retaining the genus within the family Geodiidae Gray. The results of this study suggest that three time-dependent rhaxellid assemblages can be recognized which, despite being restricted to certain depositional environments, may have biostratigraphic applications. A Portlandian assemblage described here is species-rich in comparison with known Oxfordian-Kimmeridgian assemblages. Bajocian-Callovian assemblages contain only R. sorbyana. The increased faunal diversity with time is speculatively described by an evolving Rhaxella lineage.  相似文献   

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