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A classic Late Frasnian (Devonian) chondrichthyan assemblage from southern Belgium

Ginter M., Gouwy S., Goolaerts S.

Acta Geologica Polonica

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2017

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Vol. 67, no. 3

381--392

EN

Samples from the Upper Frasnian (Devonian) of Lompret Quarry and Nismes railway section in Dinant Synclinorium, southern Belgium, yielded several chondrichthyan teeth and scales. The teeth belong to three genera: Phoebodus, Cladodoides and Protacrodus. The comparison with selected Late Frasnian chondrichthyan assemblages from the seas between Laurussia and Gondwana revealed substantial local differences of taxonomic composition due to palaeoenvironmental conditions, such as depth, distance to submarine platforms, oxygenation of water, and possibly also temperature. The assemblage from Belgium, with its high frequency of phoebodonts, is the most similar to that from the Ryauzyak section, South Urals, Russia, and the Horse Spring section, Canning Basin, Australia.

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The palaeogeographical background of Late Devonian storm events in the western part of the Holy Cross Mountains (Poland)

Vierek Aleksandra

Geologos

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2013

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Vol. 19, No. 4

257--272

EN

Late Devonian coarse-grained carbonate deposits in the Holy Cross Mountains were studied for possible storm depositional systems and catastrophic tsunami events, as it must be assumed that the investigated area was strongly affected by tropical hurricanes generated in the open ocean North of Gondwana. This assumption appears consistent with diagnostic features of carbonate tempestites at several places in the Holy Cross Mountains. Sedimentary structures and textures that indicate so are, among other evidence, erosional bases with sole marks, graded units, intra- and bioclasts, different laminations and burrowing at the tops of tempestite layers. It has been suggested before that a tsunami occurred during the Late Devonian, but the Laurussian shelf had an extensional regime at the time, which excludes intensive seismic activity. The shelf environment also excluded the generation of tsunami waves because the depth was too shallow. Additionally, the Holy Cross Mountains region was surrounded in the Devonian by shallow-marine and stable elevated areas: the Nida Platform, the Opatkowice Platform and the Cracow Platform to the South, and the elevated Lublin-Lviv area to the NE. Thus, tsunami energy should have been absorbed by these regions if tsunamites would have occurred.

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Do partly outdated palaeontological data produce just a noise? An assessment of the Middle Devonian-Mississippian biodiversity dynamics in central Asia on the basis of Soviet-time compilations

Ruban Dmitry A.

Geologos

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2011

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Vol. 17, No. 1

29--47

EN

Interregional tracing of trends and events in the biotic evolution is an important task of modern palaeobiology. In Soviet times (1917-1991), numerous palaeontological data have collected for the territory of Russia and neighbouring U.S.S.R. countries. Later, these data were compiled and published in a series of reference volumes. Although this information cannot be updated in a conventional way, it remains valuable for quantitative analyses, particularly because of its comprehensive and unique character. Assessment of the previously collected data on the stratigraphic distribution of Middle Devonian-Mississippian marine invertebrates in three regions of central Asia (central Kazakhstan, Uzbekistan and Tajikistan) reveals some general patterns of biodiversity dynamics. The total number of genera generally declined during the Givetian-Famennian, whereas a remarkable diversity peak occurred in the Visean. This is consistent with the global pattern and, thus, permits to hypothesize a regional signature of the global trends. Changes in the extinction rate differ, however, between central Asia and the Earth in its entirety, which may be explained particularly by biases in either the regional or the global records. Evidence of the Givetian and Frasnian/Famennian mass extinctions is found in the three regions under study. Results of this tentative study indicate important directions for further research and suggest that central Asia is a highly important domain for studies of mid-Palaeozoic biodiversity dynamics.

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Porównanie podatności magnetycznej (MS) i wskaźników geochemicznych środkowego i górnego franu w Kanadyjskich Górach Skalistych: implikacje dla analiz paleoklimatycznych i paleośrodowiskowych oraz interpretacji zdarzenia punctata

Śliwiński M. G., Whalen M., Day J.

Przegląd Geologiczny

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2010

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Vol. 58, nr 12

1152-1160

EN

Ongoing magnetostratigraphic and geochemical studies (including major and trace element geochemistry and stable isotopes of C, N, O) in the Canadian Rocky Mountains are providing insight into the paleoenvironmental changes of the mid-Frasnian punctata Event, a prominent marine geochemical perturbation. The data is evaluated with 1) a regional sequence stratigraphic perspective and 2) within the context of a rapidly changing Late Devonian world, characterized by numerous sedimentological and faunal perturbations leading up to the eventual Frasnian-Fammenian (F/F) mass extinction. Proxies for bottom water paleoredox conditions (Mo, V, U), oceanic primary productivity (δ13Corg, δ15Nbulku, Cu, Ni, Ba), changes in detrital input (Si, Al, K, Ti, Zr), and magnetic susceptibility display similar trends, indicating that these proxies and MS variations are inherently linked. The observed excursions suggest that changes in detrital input were the main driver of a bioproductivity increase. Elevated organic matter export from the photic zone likely led to the deposition and later preservation of organic-carbon rich facies under facilitated conditions of bottom water suboxia-anoxia. These geochemical trends were likely influenced by eustatic sea level change, but may have been enhanced by pulses of coincident orogenic activity and pulses of terrestrial afforestation. The rise and expansion of the first true forests is thought to have drastically altered nutrient fluxes to the oceans via increases in pedogenesis and the expansion of a mature soil profile. Our work is intended to complement the growing body of research aimed at elucidating the causes and understanding the effects of terrestrial and marine events of the P. punctata biozone and, more broadly, at understanding the Earth-system changes of the Late Devonian leading up to the F/F boundary.

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Bryozoans from the Jurginskaya Formation (Famennian, Upper Devonian) of the Tom-Kolyvansk area (Western Siberia, Russia)

Tolokonnikova Zoya

Geologos

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2010

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Vol. 16, No. 3

139--152

EN

Nine bryozoan species are described from the Jurginskaya Formation (Famennian, Late Devonian) from Western Siberia, Russia, namely: Leptotrypella pojarkovi Orlovski, 1961, Rhombopora subtilis Nekhoroshev, 1977, Klaucena lalolamina Yang, Hu, Xia, 1988, Eofistulotrypa famennensis sp. n., Atactotoechus cellatus sp. n., Nikiforopora jurgensis sp. n., Eridotrypella tyzhnovi sp. n., Mediapora elegans sp. n., and Klaucena gracilis sp. n. The studied assemblage shows palaeogeographical affinity with Kazakhstan, Kirgizia, Transcaucasia, China, and the United States of America.

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Late Devonian radiolarians and sponge spicules from Poland and palaeoenvironmental implications

Vishnevskaya V., Pisera A., Racki G.

Biuletyn Państwowego Instytutu Geologicznego

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2001

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nr 396

162-163