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Calpionellid biostratigraphy across the Jurassic/Cretaceous boundary in San José de Iturbide, Nuevo León, northeastern Mexico

López-Martínez R., Barragán R., Reháková D.

Geological Quarterly

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2015

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Vol. 59, No. 3

581--592

EN

Detailed bed-by-bed sampling on an outcrop of the La Casita and Taraises formations in northeastern Mexico (San José de Iturbide, Nuevo León State) allows the delimitation of the Jurassic/Cretaceous boundary. The Late Tithonian was determined by the presence of the Crassicollaria Zone (Colomi Subzone). Underlying subzones (Remanei and Brevis) were not identified due to the scarcity and poor preservation of calpionellids. The Jurassic/Cretaceous boundary was defined by the acme of the small and spherical form of the species Calpionella alpina Lorenz in sample IT-120. The Berriasian was divided into two zones and five subzones: the Calpionella Zone (Alpina, Ferasini and Elliptica subzones) and the Calpionellopsis Zone (Simplex and Oblonga subzones). The facies studied indicate that deposition during the Tithonian occurred in a toe of slope environment with occasional deep shelf incursions. Near the Jurassic/Cretaceous boundary, a sea level drop is recorded and the facies indicate a slope environment with the occurrence of a breccia level. A general deepening of the environments recorded within the frame of the Elliptica Subzone where the deposits pass into basinal facies

2

The Volgian Stage and Jurassic/Cretaceous boundary in the Panboreal Superrealm

Zakharov V., Rogov M., Kiselev D.

Volumina Jurassica

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2006

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Vol. 4, no. 1

224-226

EN

Correlation between the Volgian and Tithonian stages has been the subject of controversy for many decades. But comparison of the zonal succession within the single stage also encounters some problems. Here we propose new correlation between the Volgian Stage and Portlandian Stage. The correlation chart shows possible relations between the Volgian and basal Cretaceous zones and these of the different provinces (Fig. 1). Important for correlation records of ammonites are as follows: 1. Paracraspedites sp. and Epivirgatites cf. variabilis Shulg.occur together with E. lahuseni (Nik.) and E. cf. nikitini (Mich.) in Gorodoschi (Kiselev & Rogov 2005). 2. Laugeites sp. nov. aff. parvus Donovan occurs with Subcraspedites sowerbyi Spath, S. cf. preplicomphalus Swinn. in Gorodischi (Kiselev & Rogov 2005). 3. Craspedites okensis (d'Orb.) appears in Russia, Svalbard and Siberia nearly simultaneously. 4. Laugeites cf. planus Mesezhn. co-occurs with Epivirgatites variabilis Shulg. in Nordvik section. 5. Epilaugeites ranges into the upper part of Variabilis Zone of the Nordvik section. 6. Laugeites sp. nov. aff. parvus Donovan is recorded together with Praechetaites exoticus Shulg. and P. tenuicostatus Shulg. in Nordvik. 7. Dorsoplanites maximus Spath and D. gracilis, typical for Subpolar Urals, are known from faunas 42 and 43 of East Greenland (Callomon & Birkelund 1982). 8. Epipallasiceras in the Albani Zone of England and French coast (Wimbledon 1984), includes so-called "Epivirgatites" forms. 9. Crendonites spp. ranges from Glaucolithus to Kerberus zones of England (Wimbledon 1984) and from Anguinus to Groenlandicus zones in East Greenland (Callomon & Birkelund 1982); ammonites close to Siberian Crendonites subleslie are known from the Glaucolithes/Okusensis boundary interval of England (Wimbledon 1984). 10. Epilaugeites vogulicus (Ilov.) was recorded in the Oppressus Zone of England; subsequent ascribing of this ammonite to Okusensis Zone by Wimbledon (1984) seems not well proved. 11. Craspedites pseudonodiger Shulg. occurs in the Taimyrensis Zone of Siberia and in the uppermost Nodiger Zone of Kashpir. 12. Recent records of Volgidiscus in the Yaroslavl region permit to correlate this level with uppermost Volgian of Siberia and uppermost Portlandian. Existence of the detached zone with Subcraspedites above Volgidiscus is in Arctic (Mesezhnikov et al. 1983) and it appears in the basal Cretaceous of the Russian Platform (Mitta 2005) and England (Casey 1973). 13. Praetollia spp. is widely distributed in Arctic (Mesezhnikov et al. 1983) and appears in the basal Cretaceous of the Russian Platform (Mitta 2005) and England (Casey 1973). 14. The key event was a spreading of Boreal Hectoroceras from Siberia through Central Russia to England (Casey 1973) and East Greenland.

3

Potential Jurassic/Cretaceous boundary in northeastern China

Sha J., Chen S., Cai H., Jiang B., Yao X., Pan Y., Wang J., Zhu Y., He Ch.

Volumina Jurassica

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2006

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Vol. 4, no. 1

269-270

EN

On the basis of the geological ranges of the Buchia and dinoflagellate cyst assemblages and their global correlation, two distinct biostratigraphical boundaries (event horizons) can be distinguished in the continu ous deposits spanning the Jurassic/Cretaceous boundary in the Dong'anzhen Formation of Dong'an, Raohe County and the Dongrong Formation of boreholes SB86-11 and SB79-1 of Suibin, Suibin County of eastern Heilongjiang, northeasteren China (Fig. 1.). Level 1. The base of the Buchia fischeriana - Buchia unschensis assemblage is characterized by the occurrence of Buchia (e.g. B. unschensis) with inversoid ontogenetic growth of the right valve, and the absence of the underlying B. russiensis, one of the index species of the Buchia russiensis - Buchia fischeriana assemblage, with obliquoid ontogenetic growth of the right valve (Fig. 1, column 2b). The top of the dinoflagellate cyst Amphorula delicate assemblage underlies, but it is near this boundary (Fig. 1, column 2a). This level basically corresponds to the currently accepted Tethyan version of the Jurassic/Cretaceous boundary and the working base of the Cretaceous as recommended by the International Commission on Stratigraphy (www.stratigraphy.org) (Fig. 1, column 1), and approximately corresponds to the boundary between the Boreal Middle-Upper Volgian substages (Fig. 1, column 3). This is because the base of the Buchia unschensis Zone or the base of the Buchia fischeriana - Buchia unschensis assemblage nearly coincides with that of the Boreal Craspedites exoticus Subzone or Craspedites okensis ammonite Zone, which in turn correspond closely to the base of Tethyan Lower Berriasian Berriasella jacobi ammonite Zone (Fig. 1, column 1), which is the index ammonite zone of the Tethyan or the international chronostratigraphic base of Berriasian, and thus the base of the Cretaceous (Fig. 1, column 1). Level 2. The base of the Buchia volgensis - Buchia cf. subokensis - Buchia cf. okensis - Buchia unschensis assemblage, is characterized by those easy-to-recognize large-sized Buchia with inversoid ontogenetic growth of the right valve and even of the left valve, and absence of Buchia fischeriana (Fig. 1, column 2b). The base of the Oligosphaeridium pulcherrimum dinoflagellate cyst assemblage probably corresponds approximately to the base of this Buchia assemblage (Fig. 1, column 2a). This level is very near the Boreal version of the Jurassic/Cretaceous boundary, which corresponds approximately to the base of the Tethyan middle part of Middle Berriasian. This is because the bases of both Buchia volgensis and Buchia cf. okensis in the assemblage of Buchia volgensis - Buchia cf. subokensis - Buchia cf. okensis - Buchia unschensis are closely coincident with the base of the upper Lower Berriasian Boreal Hectoroceras kochi Zone (Fig. 1, columns 2b, 3), and the Tethyan upper Berriasella privasensis Subzone of the Tirnovella occitanica Zone of the middle part Middle Berriasian, approximately corresponds to the middle of the Boreal Lower Berriasian Substage (Fig. 1, columns 1, 3).

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Jurassic/Cretaceous boundary in the north of Middle Siberia: micropalaeontological and palynological data

Nikitenko B., Pestchevitskaya E., Lebedeva K., Ilyina V.

Volumina Jurassica

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2006

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Vol. 4, no. 1

266-267

EN

Palynological and micropalaeontological analysis of Middle Volgian - Lower Valanginian section from Nordvik Peninsular, a key section of Jurassic/Cretaceous boundary in Boreal regions, allows its detailed zonation (Fig. 1). The changes of taxonomical composition of the assemblages and stratigraphical position of foraminiferal and dinocyst zones have been analyzed taking into consideration two versions (A and B) of Jurassic/Cretaceous boundary. The level between Chetae-Sibiricus ammonite zones traditionally considered as Jurassic/Cretaceous boundary for Arctic regions (version A) is characterized by the lack of considerable taxonomical changes of foraminiferal assemblages. Dominant shifts and appearance of new taxa have been revealed slightly upward the section within the first ammonite zone of Boreal Berriasian. Some of foraminiferal zones are characterized by wide geographical distribution being traced over Siberia as well as Barents Sea region. They may be used for circum-Arctic correlations. Microphytoplankton assemblages also include a wide number of characteristic dinocysts taxa providing long distance correlation in some levels. The characteristic feature of Subzone Pareodinioideae, Cassiculasphaeridia reticulata, Batioladinium varigranosum is the first appearance of index species. It is also observed in the middle of Berriasian in Polar Ural Mountains, Moscow Syneclise, Arctic Canada. Paragonyaulacysta borealis(?) - Dingodinium spinosum(?) Zone is a reliable marker level for circum-Arctic correlations as the acme of Paragonyaulacysta borealis(?) in Upper Volgian-Berriasian, and the extinction of this species in lowermost Valanginian well traced over northern regions of Siberia, Barents Sea shelf, Arctic Canada and Greenland. First appearance of Dingodinium spinosum(?) in the lower part of Upper Volgian is observed in many regions of Western Europe, where it is regarded as the index of Dingodinium spinosum(?) Zone. In general the taxonomical changes of microphytoplankton assemblages are rather continuous with no considerable extinctions or diversity peaks. The most important taxonomical shift is observed near the base of Paragonyaulacysta borealis(?) - Dingodinium spinosum(?) Zone (version B). Palaeofacies analysis evidence that the richest foraminiferal assemblages are associated with the middle sublittoral, while the communities of lower sublittoral are less abundant and diverse. Sharp decrease of taxonomical diversity (2-3 species) and wide distribution of opportunist species Ammodiscus veteranus are typical for dysaerobic palaeoenvironments. The characteristic feature of Siberian microphytoplankton assemblages is low abundance and diversity of chorate and proximochorate dinocysts. The microphytoplankton associations strongly dominated by dinocysts with numerous gonyaulacaceans evidence rather deepwater and well aerated palaeoenvironments of lower sublittoral. Dysaerobic and poor aerated conditions of the same zone are characterized by the assemblages almost completely composed of prasinophytes.