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Early Cambrian trace fossils at the northern margin of the Arabian Plate; Telbesmi Formation, Turkey

Demírcan H., Gürsu S., Göncüoğlu M. C.

Acta Geologica Polonica

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2018

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Vol. 68, no. 2

135--145

EN

The Telbesmi Formation, at the northern margin of the Arabian Plate, Turkey, is composed of alternating darkbrown, pinky-brown fluvial arkosic sandstone/mudstones with thin-bedded cherty limestones and channel conglomerates. The formation contains rare and poorly diversified trace fossils. The siltstone/sandstone beds of levels 1 and 2 of the formation yielded, however, a moderately diverse assemblage composed of: Cochlichnus isp., Palaeophycus isp., Planolites beverleyensis, Teichichnus isp. and ?Treptichnus rectangularis. This assemblage, made up of traces left by deposit feeding organisms, represents the Scoyenia ichnofacies. Treptichnus rectangularis and Palaeophycus isp., of the assemblage, can be considered markers for the base of the Cambrian in southeast Turkey.

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Sedimentology and ichnology of Neogene Coastal Swamp deposits in the Niger Delta Basin, Nigeria

Ezeh S. C., Mode W. A., Ozumba B. M., Yelwa N. A.

Geologos

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2016

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Vol. 22, No. 3

191--200

EN

Often analyses of depositional environments from sparse data result in poor interpretation, especially in multipartite depositional settings such as the Niger Delta. For instance, differentiating channel sandstones, heteroliths and mudstones within proximal environments from those of distal facies is difficult if interpretations rely solely on well log signatures. Therefore, in order to achieve an effective and efficient interpretation of the depositional conditions of a given unit, integrated tools must be applied such as matching core descriptions with wireline log signature. In the present paper cores of three wells from the Coastal Swamp depositional belt of the Niger Delta are examined in order to achieve full understanding of the depositional environments. The well sections comprise cross-bedded sandstones, heteroliths (coastal and lower shoreface) and mudstones that were laid down in wave, river and tidal processes. Interpretations were made from each data set comprising gamma ray logs, described sedimentological cores showing sedimentary features and ichnological characteristics; these were integrated to define the depositional settings. Some portions from one of the well sections reveal a blocky gamma ray well log signature instead of a coarsening-upward trend that characterises a shoreface setting while in other wells the signatures for heteroliths at some sections are bell blocky in shaped rather than serrated. Besides, heteroliths and mudstones within the proximal facies and those of distal facies were difficult to distinguish solely on well log signatures. However, interpretation based on sedimentology and ichnology of cores from these facies was used to correct these inconsistencies. It follows that depositional environment interpretation (especially in multifarious depositional environments such as the Niger Delta) should ideally be made together with other raw data for accuracy and those based solely on well log signatures should be treated with caution.

3

Sedimentological and palaeoecological significance of the trace fossils of the Jurassic rocks of the Jhura Dome, Mainland Kachchh, western India

Patel S. J., Patel N. J.

Volumina Jurassica

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2015

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Vol. 13, no. 2

101--139

EN

The Middle to Late Jurassic succession of the Jhura Dome (Jhurio and Jumara formations) of the Mainland Kachchh, western India, comprises a ~500 m thick succession of clastic carbonates and mixed siliciclastic-carbonates, intercalated with shales. The sequence, as based on sedimentological characteristics, exhibits six sedimentary facies and four subfacies. Certain exceptional bands of the ripplemarked calcareous sandstone, shale and oolitic limestone facies are rich in ammonites, belemnites, brachiopods and bivalves. Thirty four ichnogenera were also identified and analysed paleoecologically. These trace fossils represent five ethological categories and six ichnoassemblages. Seventeen ichnoguilds are demonstrated based on space utilization for characterising the ecological complexity of ichnoassemblages. Bathymetric control of the trace fossils resulted with development of Skolithos, Cruziana and Zoophycos ichnofacies type conditions. The sedimentological and ichnological data analysis revealed seven distinctive depositional regimes ranging from offshore shelf below storm wave base to middle shoreface.

4

Trace fossil Cruziana tenella from the Furongian (Upper Cambrian) deposits of Poland

Sadlok G.

Acta Geologica Polonica

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2010

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Vol. 60, no. 3

349-355

EN

A minute, bilobate ribbon-like trace fossil, assigned to the ichnospecies Cruziana tenella, is recorded for the first time from Furongian (Upper Cambrian) strata of the Wiśniówka Formation exposed in the Wiśniówka Wielka quarry, Holy Cross Mountains, central Poland. The collected material of C. tenella is interpreted as arthropod pascichnia trails. A significant gap in size distribution and morphology between C. tenella and other Cruziana trails from Wiśniówka Wielka suggests that the former cannot be regarded as produced by juveniles of the biotaxa responsible for the latter. C. tenella from Wiśniówka Wielka was most probably produced by arthropods reaching a small adult size.

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Stanowisko z tropami kręgowców z osadów najwyższego środkowego pstrego piaskowca Gór Świętokrzyskich

Kuleta M., Niedźwiedzki G., Zbroja S.

Przegląd Geologiczny

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2006

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Vol. 54, nr 12

1081-1081, 1088

EN

TheMiddle Buntsandstein material of vertebrate tracks has been found at new site in the northern margin of the Holy Cross Mountains (central Poland). Several dozen specimens of Chirotheriidae (Chirotherium cf. barthii, cf. Brachychirotherium sp., Isochirotherium sp., and Chirotheriidae indet.) and Rhynchosauroidae (Rhynchosauroides sp., Rhynchosauroidae indet.) tracks are reported from the deposits of the Samsonów Formation (=Pseudooolithic Beds) at the Pałęgi clay pit located near Mniów. Poorly preserved cf. Capitosauroides sp. and numerous swimming animal traces were also found in this site. Those are the first finds of vertebrate tracks from the uppermost Middle Buntsandstein strata in the Holy Cross Mountains.