135
[Senckenbergianalet aea
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3 Text-figs, 21 Tabs, 11 PIs
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Frankfurt am Main, 31.08.2001 I
Bryozoa of the Upper Permian Zechstein Formation of Germany With 3 Text-figures, 21 Tables and 11 Plates
ANDREJ ERNST
Abstract The investigated bryozoan fauna of the Upper Permian Zechstein Formation includes 17 species of 9 genera, belonging mainly to the fenestellids and trepostomids and one species belonging to the tubuliporids, Corynotrypa voigtiana (KING 1850). Three new species ate described (Dyseritella microstoma sp. nov., Ulrichotrypella incrustata sp. nov., and Kingopora baderi sp. nov.). The Zechstein species of the genera Acanthocladia, Synocladia, Penniretepora and Kalvariella display close resemblance in their internal morphology, and their derivation from a common ancestor is suggested. The distribution of the bryozoans in the Zechstein Sea was apparently controlled by factors such as lateral sedimentation, distribution of microbial mats and quality of substrates. K e y w o r d s : Germany, Upper Permian, Zechstein, bryozoans, taxonomy, ecology.
Kurzfassung [Bryozoen der oberpermischen Zechstein-Formation von Deutschland.] - - Die untersuchte Fauna des Zechsteins enth/ilt 17 Arten von 9 Gattungen, ª fenestellide und trepostomide laxa, sowie eine tubuliporide Bryozoe, Corynotrypa voigtiana (KING 1850). Drei neue Arten werden beschneben (Dyscritella microstoma sp. nov., Ulrichotrypella incrustata sp. nov. und Kingopora baderi sp. nov.). Die Arten der Gattungen Acanthoctadia, Synocladia, Penniretepora und Kalvariella aus dem Zechstein zeigen groBe .~hnlichkeiten untereinander in ihrer inneren Morphologie. Ihre Abstammung von einem gemeinsamen Vorfahr wird vermutet. Die Verbreitung der Bryozoen im Zechsteinmeer wurde anscheinend von solchen Faktoren wie [ateraJe Sedimentzufuhr, Verbreitung der mikrobiel[en Matten und Substratbeschaffenheit kontrolliert.
Contents Introduction ............................................................................................................................................ Aims and methods .......................................................................................................................... Previous works ................................................................................................................................ Stratigraphy, pa[eogeography and bryozoan distribution in the Zechstein Formation ........................ Systematic approach and numerical descriptions ................................................................................. Deposition of the material .............................................................................................................. Systematic paleontology ........................................................................................................................ Paleoeco[ogical aspects ......................................................................................................................... Conc[usions ............................................................................................................................................ Acknowledgements ................................................................................................................................ References ..............................................................................................................................................
Address of the author: Dr. ANDREJ ERNST, Institut fª D-24118 Kiel. - E-mail:
[email protected]
136 136 136 137 138 •38 138 156 156 156 157
Geowissenschaften der Christian-Albrechts-Universit/it zu Kiel, Olshausenstr. 40;
136
ERNST: Bryozoa of the Upper Permian Zechstein Formation of Germany
Introduction Aims and methods The primary aim of this work is the re-study o f the type material of the Zechstein bryozoans as well as an investigation of the newly collected material. This study should obviate some problems in the systematics and biogeography of Upper Paleozoic bryozoans. Type material of the following taxa was re-studied: Dys-
critella tubulosa MOROZOVA,D. tenuimuralis MOROZOVA, Thamniscus (Keratophytes) dubius (SCHLOTHEIM), Acanthocladia (Keratophytes) anceps (SCHLOTHEIM), A. laxa KORN, A. minor KORN, Penniretepora waltheri KORN,Kalvariella typica MOROZOVA, Rectifenestella (Eschariates) retiformis (SCHLOTHEIM), Fenestella minuta KO•N, Kingopora solida KORN, Synocladia weigehi KO•N and S. dux KORN. Further material of Zechstein bryozoans in German and English museums was included for comparison. The new material was collected from different localities in Thuringia (text-fig. 1), Lower Saxony (R6merstein, Bar-
tolfelde, Staufenbª Hessen (Dorfitter, Frau Holle Felsen near Nieder Ense, Wipperich) and in England (Hylton Castle, Tunstall Hills). About 200 oriented thin sections and 100 peels from bryozoans were studied in the course of this investigation. Some samples were studied by using the scanning electron microscope CAMSCAN-Serie-2-CS-44. Unfortunately, the strong dolomitization of the reef carbonates made the study of the bryozoans from the reefs difficult.
Previous works The Zechstein bryozoan fauna was one of the earliest subjects of the systematical studies. Classic genera such as Thamniscus, Synocladia and Acanthocladia were established by researchers of the Zechstein in the 19th century. However, these studies were accomplished without considering the internal morphology of the autozooecia and the presence of polymorphs. The coral species Coralliolites columnaris SCHLOTHEIM 1813 was erroneously defined a s a bryozoan. KIYG (1850) and later GHy~rz (1861) treated this taxon as Stenopora columnaris. 18A Schwaara Trebnitz 9 Korbª Al1 9
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Text-fig. 1. Location of the investigated area and locations in Thuringia. 1. = Altenburg; 2. = Buchenberg; 3. = Drommberg; 4. - Felsenberg; 5. - Gamsenberg; 6. - Hasselberg; 7. Height 316.3; 8. - Kochsberg; 9. - Lausnitz/Autodrom; 10. = Streitberg; 11. = Leumnitz; 12. M~irzenberg; 13. - Neunhof; 14. = Pinsetberg; 15. = Ranis; 16. = Ranis (Quarry); 17. = Schlechteberg; 18. - Schwaara; 19. Spitzhª 20. - Felsenberg (Quarry); 21. - Totenhª 22. - Zschippern.
ERNST:Bryozoa of the Upper Permian Zechstein Formation of Germany Under this name different trepostomids were encluded worldwide. Finally, WEYER (1984) studied the type material of SCHLOTHEIMand recognized that ir was the coral species Callophylum columnare (SCHLOTHEIM1813). One of the later students, KORN (1930), made a careful study of the fenestellids from the Zechstein. He concentrated his investigation mostly on the peculiarities of the colony growth mode. However, his study was not supported by a description of thin seetions. DREYER (1961) used statistical methods to determine the fenestellids bryozoans from the Zechstein. MOROZOVA (1970) described the two new genera Kingopora and Kalvariella as well as three new trepostomid species from the Zechstein of Poland and Lithuania. She tried to correlate the Zechstein deposits and listed the known bryozoan taxa of the Zechstein. The taxon Coscinotrypa dubia, cited in this listas the single cystoporid in the Zechstein, is in reality an indeterminate trepostomid [possibly Dyscritella angularis (TRIZNA 1948)], figured by GEINITZ (1848) as Coscinium dubium. This taxon was cited repeatedly by Later authors (SAKAGAMI 1976; Ross 1978, 1995; G~LMOUR& MOROZOVA1999). SOUTHWOOD(1985a) extended knowledge of the Zechstein bryozoans immensely. He critically analysed the diagnoses of the Zechstein taxa and recognized the morphological affinities of species of the genera Synocladia, Thamniscus and Acanthocladia from the Zechstein. Furthermore, he described the new genus Ryhopora with a new species and one subspecies of the genus Penniretepora (SOUTHWOOD1985a, b; 1990).
Stratigraphy, paleogeography and bryozoan distribution in the Zechstein Formation The Permian in the Central Europe is divided into two parts the terrestrial Rotliegendes and the marine Zechstein. Correlation of the Zechstein Formation is still debatable. However, most references suggest that the Zechstein correlates with the Late Permian (Tatarian) age of the Russian Standard (MENN1NG 1995). Difficulties in the biostratigraphical correlation of the Zechstein with the standard scale ate explained by the highly endemic character of the Zechstein fauna and by Iack of descriptions. In addition, few uppermost Permian faunas are known elsewhere, so that the relations of the Zechstein bryozoans to other Permian faunas are not clearly understood. The Zechstein Formation displays a succession of clays, marls, carbonates and evaporites. In the whole basin four such cycles are present (RICHTER-BERNBURG 1955): Werra, StraBfurt, Leine and Aller Cycles. In the basin axe three further cycles are define& Ohre, Friesland and M61n. The bryozoan fauna occurs only in the marls and carbonates of the earliest Werra Cycle (Productusbank, Werrakarbonat). The oldest deposit of the Zechstein is the Zechstein conglomerate (text-fig. 2). This conglomerate contains a poor marine fauna including some brachiopod species (MALZAHN 1962). Bryozoans ate absent in the Zechstein conglomerate. It is overlain by black clay shale, the Kupferschiefer shale. The Kupferschiefer shale displays euxinic conditions, which developed in the Zechstein Basin after fast initial flooding of the basin (K~EaNOWSK~E et al. 1995). In the coastal areas above the storm wave base, carbonates and marls including a rich marine fauna were deposite& This unit, known as Productusbank, contains the earlist bryozoan fauna of the Zechstein Sea. With further flooding and deepening of the Zech-
137
stein Basin euxinic conditions ceased, and carbonates of the first Carbonate Cycle (Ca l) were deposited on the extensive shelf. A rich fauna flourished under normal marine conditions. On the edges of the carbonate platform and on some paleohighs stromatolithic reefs appeared. The reefs reach over 100 meters in thickness and contain a rich invertebrate fauna. Microbial mats were the most important reef builders and reveaI various morphologic structures, such as domes, sheets, and oncolites. After interruption of the influx of normal marine water from the Arctic Sea in the north, salinity increased and evaporites were deposited. The normal marine fauna became extinct. Only microbial mats and some mollusc species could survive in this extreme environment. The bedded carbonates and reefs display different biotopes. Therefore, it is justifed to recognise two general facies in the Zechstein Sea: the bedded facies and the reef facies. The bedded facies is characterised by stratified rock textutes. The typical microfacies are wackestones, grainstones and packstones. Microbial structures such as microbial laminites or oncolites are generally lacking. The carbonates of the bedded facies contains abundant foraminiferes, ostracods and locally plant remnants, the latter relating to land vicinity and apparently brackish conditions. Local occurrence of oolites indicates shallow and agitated water conditions. The rocks of the bedded facies usually contain high amounts of clay particles.Bryozoans are seemingly autochtonous in the bedded facies. The investigated reefs reveal mostly a massive rock texture. Strong dolomitisation occurs. Boundstones (stromatolites) and framestones generally dominate in the reef facies. Other microfacies such as gramstones and bafflestones occm- rarely. i
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