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The oceanic "Metis Geotectonic Event" (Callovian/Oxfordian) and its implications for the peri-Tethyan area of Poland

100%

Matyja B. , Wierzbowski A.

Volumina Jurassica

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2006

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tom Vol. 4, no. 1

60-61

EN

Condensed deposits of the Middle/Upper Callovian and/or lowermost Oxfordian are spread over vast areas of peri-Tethyan Europe from Portugal, and Spain through France, Switzerland, Germany, Poland, to Romania. A number of hypotheses for the origin of these deposits have been presented. Melendez et al. (1983) suggested that they originated due to the rise of CCD in relation to increased igneous activity. Other proposed explanations include: an extra-terrestrial event (Brochwicz-Lewifski et al. 1989) and erosional events and related taphonomic reworking of fossils during long episodes of subaerial exposure (Aurell et al. 1991). Palaeomagnetic data from the Pieniny Klippen Belt (Carpathians) of southwestern Ukraine (Lewandowski et al. 2005), and western Slovakia (Lewandowski et al. 2006) indicate that during Middle Callovian - Early Oxfordian time span a relatively fast opening of the oceanic domain took place in the outer part of the Tethys. This newly open basin (possibly corresponding to the Magura Basin in the Carpathian domain) attained 1100-1400 km in width. The rocks that formed during the Middle Callovian - Early Oxfordian in the epi-platform area of Poland bear witness to this geotectonic event. It is highly probable that the total spatial range of the geo-tectonic event within the Tethys (cf. Lewandowski et al. 2006) has been much greater, however, which indicates that the obtained results can be applied to the whole peri-Tethyan Europe. Thus, to distinguish this phenomenon independently of which particular part of the Tethys it affected, we propose to name it the "Metis Geotectonic Event"(Metis in Greek mythology was the Oceanid, and the daughter of Tethys). The appearance of condensed deposits in the epi-platform area of Poland (Giżejewska & Wieczorek 1974; Dembicz & Praszkier 2003, and other papers cited therein) remains in close time relation with recognized extension in the Tethyan domain. The short time interval of the extension (about 5 Ma) plus a large-scale displacement could have resulted in a sudden change in deposition from shallow-marine to pelagic environment, as well as in chemical corrosion of earlier accumulated carbonates. This change of deposition was controlled by relative sea-level rise as well as by upwelling of cold oceanic waters into the epi-platform area. This interpretation is consistent with recognized isotopic thermometry results indicating drastic cooling of sea water at lower middle latitudes (Dromart et al. 2003). The development of the sponge megafacies covering the peri-Tethyan part of the Late Jurassic shelf of Europe remains in close relationship with discussed phenomena. These deposits showed during Oxfordian similar spatial distribution as older condensed deposits, and represent the non-actualistic deep environment of the Late Jurassic shelf (Matyja & Pisera 1991; Matyja & Wierzbowski 1996).

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Foraminiferal assemblages as palaeoenvironmental bioindicators in Late Jurassic epicontinental platforms: Relation with trophic conditions

63%

Reolid M. , Nagy J. , Rodriguez-Tovar F. J. , Oloriz F.

Acta Palaeontologica Polonica

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2008

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tom 53

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nr 4

EN

Foraminiferal assemblages from the neritic environment reveal the palaeoecological impact of nutrient types in relation to shore distance and sedimentary setting. Comparatively proximal siliciclastic settings from the Boreal Domain (Brora section, Eastern Scotland) were dominated by inner−shelf primary production in the water column or in sea bottom, while in relatively seawards mixed carbonate−siliciclastic settings from the Western Tethys (Prebetic, Southern Spain), nutrients mainly derived from the inner−shelf source. In both settings, benthic foraminiferal assemblages increased in diversity and proportion of epifauna from eutrophic to oligotrophic conditions. The proximal setting example (Brora Brick Clay Mb.) corresponds to Callovian offshore shelf deposits with a high primary productivity, bottom accumulation of organic matter, and a reduced sedimentation rate for siliciclastics. Eutrophic conditions favoured some infaunal foraminifera. Lately, inner shelf to shoreface transition areas (Fascally Siltstone Mb.), show higher sedimentation rates and turbidity, reducing euphotic−zone range depths and primary production, and then deposits with a lower organic matter content (high−mesotrophic conditions). This determined less agglutinated infaunal foraminifera content and increasing calcitic and aragonitic epifauna, and calcitic opportunists (i.e., Lenticulina). The comparatively distal setting of the Oxfordian example (Prebetic) corresponds to: (i) outer−shelf areas with lower nutrient input (relative oligotrophy) and organic matter accumulation on comparatively firmer substrates (lumpy lithofacies group) showing dominance of calcitic epifaunal foraminifera, and (ii) mid−shelf areas with a higher sedimentation rate and nutrient influx (low−mesotrophic conditions) favouring potentially deep infaunal foraminifers in comparatively unconsolidated and nutrient−rich substrates controlled by instable redox boundary (marl−limestone rhythmite lithofacies).

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Pliensbachian, Early Jurassic radiolarians from Mount Rettenstein in the Northern Calcareous Alps, Austria

51%

Cifer T. , Gorican S. , Gawlick H.-J. , Auer M.

Acta Palaeontologica Polonica

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2020

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tom 65

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nr 1

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A new clupeid fish from the upper Miocene of Greece: A possible Hilsa relative from the Mediterranean

38%

Kevrekidis C. , Arratia G. , Bacharidis N. , Reichenbacher B.

Acta Palaeontologica Polonica

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2021

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tom 66

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nr 3