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The microcrinoid taxonomy, biostratigraphy and correlation of the upper Fredericksburg and lower Washita groups (Cretaceous, middle Albian to lower Cenomanian) of northern Texas and southern Oklahoma, USA

Gale Andrew Scott, Rashall Jenny Marie, Kennedy William James, Holterhoff Frank Koch

Acta Geologica Polonica

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2021

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Vol. 71, no. 1

1--52

EN

The stratigraphy of the upper Fredericksburg and lower Washita groups of northern Texas and southern Oklahoma is described, and biostratigraphical correlation within the region, and further afield, using micro-crinoids, ammonites, planktonic foraminiferans and inoceramid bivalves is summarised. The taxonomy of the roveacrind microcrinoids is revised by the senior author, and a new genus, Peckicrinus, is described, with the type species Poecilocrinus porcatus (Peck, 1943). New species include Roveacrinus proteus sp. nov., R. morganae sp. nov., Plotocrinus reidi sp. nov., Pl. molineuxae sp. nov., Pl. rashallae sp. nov. and Styracocrinus thomasae sp. nov. New formae of the genus Poecilocrinus Peck, 1943 are Po. dispandus forma floriformis nov. and Po. dispandus forma discus nov. New formae of the genus Euglyphocrinus Gale, 2019 are E. pyramidalis(Peck, 1943) forma pyramidalis nov., E. pyramidalis forma radix nov. and E. pyramidalis forma pentaspinusnov. The genera Plotocrinus Peck, 1943, Poecilocrinus and Roveacrinus Douglas, 1908 form a branching phylogenetic lineage extending from the middle Albian into the lower Cenomanian, showing rapid speciation, upon which a new roveacrinid zonation for the middle and upper Albian (zones AlR1-12) is largely based. Outside Texas and Oklahoma, zone AlR1 is recorded from the lower middle Albian of Aube (southeastern France) and zones AlR11-CeR2 from the Agadir Basin in Morocco and central Tunisia. It is likely that the zonation will be widely applicable to the middle and upper Albian and lower Cenomanian successions of many other regions.

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Towards an integrated Jurassic biostratigraphy for eastern Greenland

Kelly S. R. A., Gregory F. J., Braham W., Strogen D. P., Whitham A. G.

Volumina Jurassica

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2015

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Vol. 13, no. 1

43--64

EN

The thick and relatively complete Jurassic succession of eastern Greenland provides a unique biostratigraphic record for the North Atlantic region. The main biostratigraphic control for the succession has been provided by molluscs, especially ammonites and to a lesser extent by bivalves and belemnites. The late John Callomon and colleagues recognised 93 Boreal ammonite-bearing horizons in the Mid to Late Jurassic. This provides a reliable backbone to the biostratigraphy of these strata, prompting a palynological colleague to comment that they are the “Policemen of Jurassic Stratigraphy”. Other biostratigraphically significant microfossil and palynological groups, can be calibrated against this standard, but on their own cannot achieve the same precision. The Early Jurassic of eastern Greenland does not have such fine control as later parts of the period. No single biostratigraphic group can be used successfully throughout the interval, and there are only three significant ammonite faunas during this period. Reliance on various different organisms is necessary to cope with the changing range of marine to non-marine environments. CASP field-work from 1990 to 2012 has resulted in the collection of much biostratigraphic material. In this article, published data are summarised together with previously unpublished data in the form of a unified table. The integrated chart shows detailed columns for the whole eastern Greenland Jurassic. It demonstrates the ammonite, palynological and microfossil events/biozones and horizons which are correlated by time. More limited information is available on belemnites, bivalves and macroflora. This is the first time such an integrated biostratigraphic scheme has been assembled for the Jurassic of eastern Greenland. It will be of value to the offshore oil-industry in the northern North Atlantic and on the Barents Shelf as well as to field geologists in Greenland.

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Integrated biostratigraphy across the Aalenian/Bajocian boundary of the Central High Atlas, Morocco

Sadki D.

Volumina Jurassica

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2015

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Vol. 13, no. 1

27--42

EN

This work presents an integrated biostratigraphic study across the Aalenian/Bajocian boundary of the Central High Atlas of Morocco. The data that are the basis for this study were obtained from the region of Rich that is located in the center of the basin of the Moroccan High Atlas. This region presents a thick Aalenian–Bajocian succession with continuous marine sedimentation, which offers a rich and varied fauna whose analysis enables the compilation of an integrated biostratigraphy based on the different paleontological groups: ammonites, belemnites, brachiopods, bivalves, gastropods, calcareous nannofossils, foraminifera and ostracods.

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Integrated stratigraphy (radiolarians and calcareous nannofossils) of the Middle to Upper Jurassic Alpine radiolarites (Lombardian Basin, Italy):constraints to a genetic interpretation

Chiari M., Cobianchi M., Picotti V.

Volumina Jurassica

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2006

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Vol. 4, no. 1

152-153

EN

New biostratigraphic data obtained by integrating radiolarian and calcareous nannofossil stratigraphy document a depositional history for the Middle to Upper Jurassic radiolarites of the Southern Alps characterized by strong fluctuations in the sedimentation rates, associated with shifts from turbiditic to hemipelagic sedimentary processes. The radiolarites were studied in four sections located in different settings of the Lombardian Basin, a rifted basin of the northern Adriatic Plate, where this interval is known as Selcifero Lombardo Formation. The latter consists of two members, the Radiolarite and the Rosso ad Aptici, respectively, and passes, gradually, upwards to the Maiolica Formation. The sections studied were sampled in detail to obtain data on their lithology (using facies and microfacies analyses and calcimetry) and their nanno- and microfossils content (especially radiolarians, and calpionellids). An almost complete record of radiolarians was detected throughout the Selcifero Lombardo Formation, so that the Radiolarian Zonation (UAZones) for the Middle to Upper Jurassic interval, partially integrated with calcareous nannofossils and calpionellid biostratigraphic data, was successfully applied. Accordingly, the Radiolarite unit correlates with the Lower Bathonian (UAZ. 5) to the Kimmeridgian (UAZ. 11) interval, and the Rosso ad Aptici member displays an age spanning from Kimmeridgian to the base of Upper Tithonian (from the UAZ. 10-11 to nannofossil NJK zone). The base of the Maiolica Formation is assigned to Upper Tithonian, in agreement with the previous authors. We interpret the radiolarites as pelagic sediments relatively enriched in radiolarian during a long time span of basin starvation, due to the near absence of periplatform exportation. Because the very low sedimentation rates equally imply low radiolarian productivity, it is not necessary to claim for high water fertility during Middle to Late Jurassic, even if this latter condition likely played a role in development of the carbonate platforms.