Coniacian sandstones from the North Sudetic Synclinorium revisited: palaeoenvironmental and palaeogeographical reconstructions based on trace fossil analysis and associated body fossils
Loading...
Date
2018-04
Authors
Advisor
Editor
Journal Title
Journal ISSN
Volume Title
Publisher
Instytut Geologii UAM
Title alternative
Abstract
The Coniacian quartz sandstones (Żerkowice Member, Rakowice Wielkie Formation) that crop out at quarries near
Czaple-Nowa Wieś Grodziska (North Sudetic Synclinorium) contain a low-diversity assemblage of trace fossils: Gy
rochorte isp., Ophiomorpha nodosa Lundgren, 1891, Ophiomorpha isp., Phycodes cf. curvipalmatum (Pollard, 1981), ?Phy
codes isp., Planolites cf. beverleyensis (Billings, 1862), Thalassinoides paradoxicus Woodward, 1830 and ?Thalassinoides isp.
Moreover, interesting compound burrow systems, here referred to as Thalassinoides-Phycodes cf. palmatus and ?Thalassi
noides-Phycodes, were recognised at the Czaple Quarry. Additionally, ?Gyrochorte isp., Phycodes cf. flabellum (Miller and
Dyer, 1878) and ?Treptichnus isp. were encountered at correlative levels in the Rakowice Małe Quarry. Some of these
ichnotaxa have not been recorded previously from Coniacian sandstones of the Żerkowice Member. Additionally, in
slabs of these sandstones, the gastropod Nerinea bicincta Bronn, 1836 and the bivalve Lima haidingeri Zittel, 1866 were
found. These interesting finds, in particular the gastropods, were already noted from the study area in the first half of
the twentieth century by Scupin (1912–1913). Ethologically, the trace fossil assemblage is represented by domichnia
or domichnia/fodinichnia (Ophiomorpha, Thalassinoides), fodinichnia (Phycodes) and pascichnia (Gyrochorte, Planolites).
The compound burrow systems (Thalassinoides-Phycodes) are interpreted as dwelling/feeding structures. The possi-
ble tracemakers are crustaceans (Ophiomorpha, Thalassinoides) or worm-like animals (annelids and other) (Planolites,
?Phycodes, Gyrochorte and ?Treptichnus). The assemblage of trace fossils is characteristic of the Skolithos ichnofacies and
Cruziana ichnofacies, typical of shallow-marine settings. Ichnological studies, as well as the presence of accompanying
fossils (bivalves, gastropods), confirm the palaeoenvironmental reconstruction of the Żerkowice Member sandstones by
Leszczyński (2010). That author interpreted the Coniacian sandstones as bar and storm deposits laid down in a shallow
epicontinental sea (mainly the foreshore-upper shoreface; up to the middle shoreface) under normal oxygenation and
salinity, in soft substrate, above fair-weather wave base. The deposition of the Żerkowice Member sandstones is linked
to a regression that started after uplift of the southeastern part of the North Sudetic Synclinorium.
Description
Sponsor
Keywords
ichnology, Upper Cretaceous, Sudetes Mountains, Żerkowice Member, foreshore, shoreface
Citation
Geologos, 2018, 24, 1, s.29-53
ISBN
978-83-232187-4-6