Science and earth science

Acta Geologica Polonica

Content

Acta Geologica Polonica | 2019 | vol. 69 | No 1 |

Abstract

A microfauna of small shelly fossils (SSF) is reported here for the first time from middle Cambrian (Series 3, Stage 5) subsurface strata of the Torgau-Doberlug Syncline (TDS), Central Germany. Considering that this microfauna is strongly limited and poorly preserved the material is quite abundant and diverse. The assemblage consists of molluscs (pelagiellids, bivalves), coeloscleritophorans (chancelloriids, halkieriids), poriferids, protoconodonts, cambroclaves, hyoliths, brachiopods, and disarticulated echinoderm remains. Additionally, a probable pterobranch hemichordate is noted. The assemblage is dominated by epifaunal suspension feeders from mid- to outer shelf depositional settings. Stratigraphically it represents (together with rare trilobites) the oldest middle Cambrian (Series 3, Stage 5) fauna known from Central Germany and the entire Saxothuringian Zone. Regardless the taphonomic problems related to the SSF occurrence, close palaeobiogeographic relations are indicated with the Mediterranean shelf of West Gondwana (especially with the areas of southwestern Europe and Morocco). The reported microfauna coupled with recent trilobite and palynomorph research supports assumptions that the Cambrian succession in the TDS is by far more complete than hitherto suggested, emphasizing its importance as a region yielding Cambrian rocks in Central Europe.

Go to article

Abstract

The Shotori Range of east-central Iran (east of Tabas) has yielded Famennian ammonoid assemblages dominated by the family Sporadoceratidae. Four genera Maeneceras Hyatt, 1884, Iranoceras Walliser, 1966, Sporadoceras Hyatt, 1884 and Erfoudites Korn, 1999 are represented. The conodont assemblage of one sample containing Iranoceras revealed an Upper marginifera Zone age. The ammonoid assemblages are characterised by comparatively large specimens; they reach conch diameters of 300 mm (including the body chamber) and the mean size is larger than 100 mm. The preservation of the material from the Shotori Range and size comparison with sporadoceratid assemblages from the Anti-Atlas of Morocco and the Rhenish Mountains of Germany suggest that hydraulic sorting has resulted in a bias towards large conchs, explaining the size distribution, rather than latitudinal differences. The new species Maeneceras tabasense is described; the genus Iranoceras is revised with a new description of the two species Iranoceras pachydiscus (Walliser, 1966) and Iranoceras pingue (Walliser, 1966).

Go to article

Abstract

The Family Neokoninckophyllidae and its type genus Neokoninckophyllum Fomichev, 1939 (type species: N. tanaicum Fomichev, 1939) are discussed and emended. In addition, the genera Orygmophyllum Fomichev, 1953 and Yuanophylloides Fomichev, 1953, originally included in the Families Campophyllidae Wedekind, 1922 and Lophophyllidae Grabau, 1928, respectively, are emended as well and transferred to the Neokoninckophyllidae. Two early Bashkirian species, viz. Yuanophylloides rectus (Vassilyuk in Aizenverg et al., 1983) and Y. inauditus (Moore and Jeffords, 1945), and the Moscovian Neokoninckophyllum sp. nov. are described on the basis of new collections from the Donets Basin. Neokoninckophyllum tanaicum, Yuanophylloides gorskyi Fomichev, 1953 (both Moscovian in age) and Y. cruciformis Fomichev, 1953 (latest Bashkirian), are redescribed on the basis of peels taken from Fomichev’s (1953) type specimens. Derivation of the Family Neokoninckophyllidae from the Subfamily Dibunophyllinae Wang, 1950 is postulated and phylogenetic links within the former are hinted at. The occurrence of Yuanophylloides inauditus in both the Donets Basin and the Western Interior Province of North America points to marine communication between those areas during the Bashkirian. The slightly earlier appearance of the oldest neokoninckophyllids in the Donets Basin, in comparison to North America (i.e., R1 vs R2 ammonoid biozones), documents the common roots and monophyletic development of the Neokoninckophyllidae in both areas.

Go to article

Abstract

The aim of this study was to reconstruct the location mechanism of a Triassic sandstone wedge within folded Palaeozoic rocks. A vertically oriented Buntsandstein succession (Lower Triassic) from Józefka Quarry (Holy Cross Mountains, central Poland), steeply wedged within folded Devonian carbonates, is recognised as an effect of normal faulting within a releasing stepover. The sandstone succession, corresponding to the Zagnańsk Formation in the local lithostratigraphic scheme, is represented by two complexes, interpreted as deposits of a sand-dominated alluvial plain (older complex), and coarse-grained sands and gravels of a braided river system (younger complex). The sandstone complex was primarily formed as the lowermost part of the several kilometres thick Mesozoic cover of the Holy Cross Mountains Fold Belt (HCFB), later eroded as a result of the Late Cretaceous/Paleogene uplift of the area. Tectonic analysis of the present-day position of the deformed sandstone succession shows that it is fault-bounded by a system of strike-slip and normal faults, which we interpret as a releasing stepover. Accordingly, the formation of the stepover in the central part of the late Palaeozoic HCFB is evidence of a significant role of strike-slip faulting within this tectonic unit during Late Cretaceous/Paleogene times. The faulting was probably triggered by reactivation of the terminal Palaeozoic strike-slip fault pattern along the western border of the Teisseyre–Tornquist Zone.

Go to article

Abstract

This study is a detailed lithofacies analysis of the Wiar and Leszczyny members of the deep-marine Ropianka Formation (Campanian–Paleocene) exposed in the Hucisko Jawornickie section of the Skole Nappe, Polish Carpathian Flysch. The sedimentary succession (>400 m thick) represents a channelized lobe complex that prograded at the base of submarine slope. Seven sedimentary facies are recognized as a record of the principa modes of sediment deposition. Based on their stratigraphic grouping and grain-size trends, six facies associations are distinguished as representing specific sub-environments of the depositional system: distributary channels, channel-mouth lobes, channel levees, crevasses and interlobe basin plain with crevasse splays. The individual facies associations are characterized statistically and their internal facies organization is analysed by the method of embedded Markov chains to reveal the time pattern of depositional processes. The environmental changes indicated by the vertical succession of facies associations are attributed to the autogenic processes of the distributary channel shifting within an aggrading lobe area and the lateral switching of depositional lobes. Eustatic influences are likely, but difficult to ascertain with poor biostratigraphic data. The bulk basinward advance of the base-of-slope system was probably due to a pulse of the tectonic narrowing of the synclinal Skole Basin.

Go to article

Abstract

Many granitic intrusions display evidence of magma mixing processes. The interaction of melts of contrasting composition may play a significant role during their generation and evolution. The Strzegom-Sobótka massif (SSM), located in the Sudetes (SW Poland) in the north-eastern part of the Bohemian Massif of the Central European Variscides, exhibits significant evidence of magma mingling on the macro- and micro-scales. The massif is a composite intrusion, with four main varieties: hornblende-biotite granite (with negligible amount of hornblende) and biotite granite in the western part, and two-mica granite and biotite granodiorite in the eastern part. Field evidence for magma mingling is easily found in the biotite granodiorite, where dark enclaves with tonalitic composition occur. Enclaves range from a few centimeters to half a meter in size, and from ellipsoidal to rounded in shape. They occur individually and in homogeneous swarms. The mixing textures in the enclaves include fine-grained texture, acicular apatite, rounded plagioclase xenocrysts, ocellar quartz and blade-shaped biotite. The most interesting feature of the enclaves is the presence of numerous monazite-(Ce) crystals, including unusually large crystals (up to 500 μm) which have grown close to the boundaries between granodiorite and enclaves. The crystallization of numerous monazite grains may therefore be another, previously undescribed, form of textural evidence for interaction between two contrasting magmas. The textures and microtextures may indicate that the enclaves represent globules of hybrid magma formed by mingling with a more felsic host melt. Chemical dating of the monazite yielded an age of 297±11 Ma.

Go to article

Editorial office

Editor-in-Chief
Ireneusz Walaszczyk, Faculty of Geology, University of Warsaw, Poland

Editorial Advisory Board Andrzej Radwański, University of Warsaw, Poland Zdzisław Bełka, Adam Mickiewicz University Poland Max Laurence Coleman, The University of Reading, U.K. Jerzy Fedorowski, Adam Mickiewicz University Poland Ryszard Gradziński, Polish Academy of Sciences, Poland Peter J. Harries, University of South Florida, USA John W.M. Jagt, Natuurhistorisch Museum Maastricht, The Netherlands William James Kennedy, Oxford Natural History Museum, U.K. Jan Kutek, University of Warsaw, Poland Anatoly MikhailovicNikishin, Moscow State Univesity, Russia Nestor Oszczypko, Jagiellonian University, Poland Michał Szulczewski, University of Warsaw, Poland Karl-Armin Tröger, Technische Universiät, Freiberg, Germany Sue Turner, Queensland Musem, Australia Alfred Uchman, Jagiellonian University, Poland Jerzy Znosko, Stage Geological Survey, Poland Andrzej Żelaźniewicz, Polish Academy of Sciences, Poland

Contact

Institute of Geology
University of Warsaw
Al. Zwirki i Wigury 93
02-089 Warszawa, Poland
Phone: +48-22-5540422
Fax: +48-22-5540001
e-mail: agp@uw.edu.pl

This page uses 'cookies'. Learn more