Acta Geologica Polonica, Vol. 63 (2013), No. 4, pp. 555–610 DOI: 10.2478/agp-2013-0025 Silicified sea life – Macrofauna and palaeoecology of the Neuburg Kieselerde Member (Cenomanian to Lower Turonian Wellheim Formation, Bavaria, southern Germany) SIMON SCHNEIDER1, MANFRED JÄGER2, ANDREAS KROH3, AGNES MITTERER4, BIRGIT NIEBUHR5, RADEK VODRÁŽKA6, MARKUS WILMSEN5, CHRISTOPHER J. WOOD7 AND KAMIL ZÁGORŠEK8 1CASP, University of Cambridge, West Building, 181A Huntingdon Road, Cambridge, CB3 0DH, UK and GeoZentrum Nordbayern, Paleobiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Loewenichstr. 28, 91054 Erlangen, Germany. E-mail: [email protected] 2Lindenstr. 53, 72348 Rosenfeld, Germany. E-mail: [email protected] 3Natural History Museum Vienna, Geology-Palaeontology, Burgring 7, 1010 Wien, Austria. E-mail: [email protected] 4Hoffmann Mineral GmbH, Münchener Str. 75, 86633 Neuburg an der Donau, Germany. E-mail: [email protected] 5Senckenberg Naturhistorische Sammlungen Dresden, Museum für Mineralogie und Geologie, Paläozoologie, Königsbrücker Landstr. 159, 01109 Dresden, Germany. E-mails: [email protected]; [email protected] 6Academy of Sciences of the Czech Republic, Institute of Geology, Rozvojová 269, 16502 Praha 6, Czech Republic. E-mail: [email protected] 7Scops Geological Services Ltd., 31 Periton Lane, Minehead, Somerset TA24 8AQ, UK. E-mail: [email protected] 8Department of Paleontology, National Museum, Vaclavske nam. 68, 11579 Praha 1, Czech Republic. E-mail: [email protected] ABSTRACT: Schneider, S., Jäger, M., Kroh, A., Mitterer, A., Niebuhr, B., Vodrážka, R., Wilmsen, M., Wood, C.J. and Zágoršek, K. 2013. Silicified sea life – Macrofauna and palaeoecology of the Neuburg Kieselerde Member (Cenomanian to Lower Tur- onian Wellheim Formation, Bavaria, southern Germany). Acta Geologica Polonica, 63 (4), 555–610. Warszawa. With approximately 100 species, the invertebrate macrofauna of the Neuburg Kieselerde Member of the Wellheim Formation (Bavaria, southern Germany) is probably the most diverse fossil assemblage of the Danubian Cretaceous Group. Occurring as erosional relicts in post-depositional karst depressions, both the Cretaceous sediments and fos- sils have been silicified during diagenesis. The Neuburg Kieselerde Member, safely dated as Early Cenomanian to Early Turonian based on inoceramid bivalve biostratigraphy and sequence stratigraphy, preserves a predominantly soft-bottom community, which, however, is biased due to near-complete early diagenetic loss of aragonitic shells. The community is dominated by epifaunal and semi-infaunal bivalves as well as sponges that settled on various (bio-) clasts, and may widely be split into an early bivalve-echinoid assemblage and a succeeding sponge-brachiopod as- semblage. In addition to these groups we document ichnofauna, polychaete tubes, nautilids and bryozoans. The fauna provides evidence of a shallow to moderately deep, calm, fully marine environment, which is interpreted as a large- scale embayment herein. The fauna of the Neuburg Kieselerde Member is regarded as an important archive of lower Upper Cretaceous sea-life in the surroundings of the Mid-European Island. Key words: Late Cretaceous; Danubian Cretaceous Group; Macro-invertebrates; Facies; Silica diagenesis; Stratigraphy. 556 SIMON SCHNEIDER ET AL. INTRODUCTION Siliceous Earth is not only in great demand for industrial applications, but is also of particular scientific interest, Although most people may never have heard about especially with regard to its formation. As an additional the Neuburg Kieselerde Member, which is mined as peculiarity, the Neuburg Siliceous Earth today occurs “siliceous earth” in the area of Neuburg an der Donau only in the form of erosional relicts, infilling post-depo- (Bavaria, southern Germany; Text-fig. 1), the eponymous sitional karst depressions in the Upper Jurassic rocks of sediment has entered a majority of our households the southwestern Franconian Alb. The present study fo- straight through the front door, hidden in toys, jars and cuses on the macrofossil content of the Neuburg tubes. However, due to its unique composition of up to Siliceous Earth, trying to explain the genesis of the sed- 99 weight percent of amorphous to nanocrystalline iments from a palaeoecological point of view. Further- silica and variable quantities of kaolinite, the Neuburg more, we aim at providing a complete, taxonomically up- Text-fig. 1. Geographical overview. Green colour indicates surface exposures and karst depressions filled with sediments of the Wellheim Formation. Red dots indicate localities mentioned in the text that yielded fossils or have been sampled for petrographic analysis 557 MACROFAUNA AND PALAEOECOLOGY OF THE CENOMANIAN TO LOWER TURONIAN OF SOUTHERN GERMANY to-date inventory of the macrofauna, based on the entire sion für Kreide-Stratigraphie (SKS) of the Deutsche material available from public collections, including a Stratigraphische Kommission (DSK) (Text-fig. 2). With comprehensive photographic documentation. regard to lithostratigraphy, all other terms listed below are synonymous with or describe parts of the Neuburg Nomenclature Kieselerde Member (see stratigraphy section below for details). During more than 130 years, a variety of formal and Neuburger Kieselerde; English: Neuburg Siliceous informal terms have been created for the Neuburg Earth (Göske and Kachler 2008): Informal term, cur- Siliceous Earth, its contents and its components. Many rently applied for the unconsolidated, fine-grained, car- of these terms are outdated or have been misapplied in bonate-free, predominantly siliceous sediment of the the literature. We therefore provide a short list of the Neuburg Kieselerde Member, which is mined for in- most important terms. Only the synonyms that refer to dustrial applications. the Neuburg Kieselerde Member in particular are con- Neuburger Weiß (Gümbel 1889, 1891), Kieselsaure sidered in the following part and not those terms that are Tonerde (Hasselmann 1895a, b), Neuburger Kiesel- related to the Wellheim Formation in general (comp. kreide (Kalkowsky 1902, cited in Schneider 1933), Niebuhr et al. 2009). Kieselerde von Neuburg a.d.D. (Schneider 1933), glo- Neuburg Kieselerde Member of the Wellheim For- bularer Tripel, Silikolith (Prokopowicz 1951), mation: Official lithostratigraphic term, introduced by Neuburger Weißerde, Weißer Bollus, Kieselweiß, Kiesel- Niebuhr (in Niebuhr et al. 2009), modified by Wilmsen mulm: Outdated informal terms, being synonymous and Niebuhr (2010) and approved by the Subkommis- with Neuburg Siliceous Earth. Text-fig. 2. Stratigraphic subdivision of the Wellheim Formation and corresponding lithostratigraphic units of the Regensburg–Kelheim area. Sequence boundaries (SB), sea level changes, lithofacies and inoceramid ranges are indicated. Absolute ages are obtained from Gradstein et al. (2012); the value in brackets is obtained from cyclostratigraphy by M.W. Abbreviations: Cunningt. = Cunningtoniceras; Ac. = Acanthoceras; In. = Inoceramus; Me. = Metoicoceras; Ne. = Neocardioceras; Wa. = Watinoceras; My. = Mytiloides; Co. = Collignoniceras; subherc. = subhercynicus; herc. = hercynicus; Neu–Wel = Neuburg–Wellheim 558 SIMON SCHNEIDER ET AL. Opaline nodules: Informal term currently applied tipper. Rising personnel expenses and technical diffi- for the silicified rock portions, which may occur scat- culties finally led to the establishment of opencast tered or enriched in layers in the Neuburg Siliceous mines, and today approximately 145,000 tons of Earth (Niebuhr et al. 2009; Wilmsen and Niebuhr siliceous earth per annum are exploited (Hoffmann 2010; see Text-figs 3–5). Locally, these nodules may Mineral 2003). After processing, 30–50 % of the raw enclose fossils, especially the inoceramid bivalve in- material is utilisable, and sold and exported in variant dex taxon Inoceramus crippsi crippsi. qualities under the trade names Sillitin and Sillikolloid Kreidesteine (Kalkowsky 1902, cited in Schneider (Hoffmann Mineral 2003, 2008). 1933; Prokopowicz 1951), Dichtquarzitbrocken (Schneid 1915): Wellheimer Inoceramenquarzit History of research (Lehner 1933), Gaisit (Prokopowicz 1951; Kempcke 1958a; Doppler et al. 2002), Zementquarzit (Hoff- Going along with mining, research on the Neuburg mann et al. 1955): Informal, erroneous and/or out- Kieselerde Member also has an impressive tradition, dated terms being synonymous with opaline nodules. starting with an initial documentation of the “Neuburger Quartzites are metamorphic rocks, while the term Weiß” by Gümbel (1889, 1891), characterized as a Gaize (Germanised term: Gaisit) was established for soft, powdery, white siliceous substance of unknown fine-grained, calcareously cemented or porous glau- origin that consisted of 89.1 % insoluble silica, 0.6 % conitic sandstones or calcarenites. Both rock types do soluble silica, 6.5 % clay minerals and iron oxide, and not occur in the Neuburg Kieselerde Member. 3.8 % water and organic material (Gümbel 1891, p. 296). Gümbel (1891) did not find any fossils and as- Mining and applications sumed that the Neuburg Siliceous Earth formed during the Cenozoic. A few years later, Hasselmann (1895a, b) Presumably, Neuburg Siliceous Earth was already published an additional geochemical analysis of the used by the Romans, in particular for the surfacing of sediment, which he termed “Kieselsaure Tonerde” kilns and as a basic material for pottery (Schneider (= silicic alumina). After