Meded. Werkgr. Tert. Kwart. Geol. 24(3) 193-224 3 figs, 1 tab., 2 pis. Leiden, September 1987 A Late Oligocene (Chattian B) mollusc fauna from the clay-pit of Galten Brickworks at Nørre Vissing, Jylland, Denmark by K.I. Schnetler Langa, Denmark and C. Beyer Geological Institute, University of Aarhus, Arhus, Denmark Schnetler, K.I., & C. Beyer. A Late Oligocene (Chattian B) mollusc fauna from the clay-pit of Galten Brickworks at Norre Vissing, Jylland, Denmark. — Meded. Werkgr. Tert. Kwart. Geol., 24(3): 193-224, 3 figs, 1 tab., 2 pis. Leiden, September 1987. A rich Late Oligocene mollusc fauna from Norre Vissing near Skan- derborg Qylland, Denmark) was studied. The locality and the exposed described in the litho- sequence Eire detail, and and biostratigraphical positions are discussed. A list of the mollusc species is given, and com- parisons with other Danish and German faunas of Late Oligocene age are made. In the discussions several and systematical part on species are given five new species are introduced, viz. Solariella (Solariella) vissingensis n. sp., S. (S.) ronaldjansseni n. sp., ? Cirsotrema (s. lat.) nielseni n. sp., Glibertturricula and Pleurotomella anderseni ariejansseni n. sp., (Pleurotomella) The Nucula harde is introduced for n. sp. name (Lamellinucula) ri n. nom. Nucula donaciformis Harder, 1913 non Hall, 1847. K.I. Schnetler, Fuglebakken 14, Stevnstrup, DK-8870 Langa, Denmark; C. Beyer, Geological Institute, University of Aarhus, DK-8000 Arhus C, Denmark. Contents: Samenvatting, p. 194 Dansk 194 sammendrag, p. Introduction, p. 195 195 Locality, p. 196 Lithological description, p. 194 198 Lithostratigraphical correlation, p. 199 Biostratigraphical correlation, p. The of the in its 199 age Brejning Clay type locality, p. 200 Material, p. List of mollusc species, p. 202 Systematical part, p. 202 with Danish Late 221 Comparison Oligocene faunas, p. with German Late 222 Comparison Oligocene faunas, p. 222 Palaeoecological interpretations, p. 223 Acknowledgements, p. 223 References, p. Samenvatting Nørre De laat-oligocene molluskenfauna van Vissing, Jutland, Denemarken. De vindplaats Nørre Vissing bij Skanderborg (Jutland, Denemarken) heeft de rijkste mollusken- het bekend is. Er is sectie die faunaopgeleverd, die uit Deense Laat Oligoceen een aanwezig, verge- is de Formatie De de door hiaat lijkbaar met Vejle Fjord (Oligoceen/Mioceen). grens met een ge- scheiden onderliggende Sovind Marl Formatie is goed ontsloten. alsmede Er wordt een lithologische beschrijving van de opeenvolging gegeven, een paleo- oecologische interpretatie, en litho- en biostratigrafische correlaties. Op grond van de Pectinidae wordt unit 2 (Brejning Clay Member) tot het Chattien B gerekend. Enkele beschadigde Chattien A fossielen worden als verspoeld beschouwd. ‘Er worden 145 soorten mollusken genoemd. De volgende nieuwe soorten worden beschreven: Solariella Solariella ? Cirsotrema (Solariella) vissingensis n. sp., (Solariella) ronaldjansseni n. sp., (s. lat.) nielseni Glibertturricula and Pleurotomella anderseni Voor n. sp., ariejansseni n. sp., (Pleurotomella) n. sp. Nucula 1913 1847 de nieuwe harderi In donaciformis Harder, non Hall, wordt naam Nucula ingevoerd. het systematische gedeelte worden verder diverse soorten besproken; karakteristieke soorten zijn afge- beeld op twee platen. Dansk sammendrag En Øvre Oligocæn molluskfauna fra Nørre Vissing, Jylland, Danmark. i Nørre Galten Teglværks lergrav Vissing nær Skanderborg har givet den største kendte mollusk- fauna fra Danmark Øvre Oligocæn. På lokaliteten er sedimenter, sammenlignelige med Vejle Fjord Formationen desuden til den Søvind (Oligocæn-Miocæn), blottede, og er grænsen underliggende Mari Formation let tilgængelig. I det beskrives lokaliteten litho- foreliggende arbejde og lagfølgens lithologi, og og biostratigra- fiske korrelationer af På af foreslås, ligesom en tolkning palæomiljøet gives. basis pectiniderne hen- føres unit 2 (Brejning Clay Member) til Chattien B, idet nogle få dårligt bevarede pectinider, der A kunne indicere en Chattien alder, betragtes som omlejrede. 195 I faunalisten anføres 145 molluskarter. Disse nye arter beskrives: Solariella (Solariella) vissingensis Cirsotrema n. sp., Solariella (Solariella) ronaldjansseni n. sp., ? (s. lat.) nielseni n. sp., Glibertturricula arie- Pleurotomella anderseni Nucula jansseni n. sp., og (Pleurotomella) n. sp. For donaciformis Harder, 1913 non 1847 foreslås det Nucula harderi. I den del diskuteres flere Hall, nye navn systematiske arter, og på to tavler arbildes karakteristiske arter. Introduction (author: Schnetler) Danish mollusc fauna has been studied since the of Harder No Late Oligocene papers (1913) and An and Eriksen (1937). important material, however, has been brought together from classic new ex- in the last The is the result of the mollusc fauna of Norre posures ten years. present paper a study on in of mollusc Vissing, situated near Skanderborg Jylland. This fauna yielded the largest number all Danish Late localities. The list of 145 68 of species among Oligocene species comprises species, which are recorded from Denmark for the first time. The clay-pit at Norre Vissing is also interesting from a stratigraphical point of view, as the unconformity between the Eocene Sovind Marl and the Oligo-Miocene Vejle Fjord Formation is well-exposed. LOCALITY (authors: Schnetler & Beyer) In text-fig. 1 the geographical position of the Norre Vissing locality is indicated. The clay-pit is situated about 1 km NNW of Norre Vissing (about 22 km W of Arhus). The UTM coordinates Fig. 1. Geographical situation of the clay-pit of Galten Brickworks at Norre Vissing, Denmark. Fragment of the 1 : 25.000 map-sheet “1214 I NØ Galten”. Reproduced with permission of the Geodetic Institute (A.398/86). Copyright. 196 I NH (1 : 25,000 map-sheet 1214 N0 Galten) are 525 212. Previous descriptions of this locality can Friis al. and al. Vis- be found in Friis & Nielsen (1979), et (1981) Heilmann-Clausen et (1985). Norre in sing was also mentioned Schnetler (1985). The clay-pit is currently worked by Galten Brickworks, which has been digging here for about 16 Excavation takes once and the Sovind Marl Formation is years. place only a year, exclusively used, from the bottom of the for which the Late has to be removed. After com- pit, purpose Oligocene clay pletion of the excavation the Late Oligocene clay is redeposited in the excavation, in order to get the clay-pit into level again. Thus, only for a short period each year good sections are available. The Late In the of 1985 and Oligocene sedimentsweather quickly, partly due to a high pyrite content. autumns accessible. Smaller of the 1986 good sections were or greater parts sequence are continuously present in the and northern frontsof the The resembles similar described western clay-pit. sequence a section, Andersen As At by (1938) from a marl-pit at (see illustration in Andersen, 1944, fig. 344). both localities the is disturbed tectonics. sequence by glacial LITHOLOGICAL DESCRIPTION (authors: Schnetler & Beyer) of that be In the northern front of the clay-pit about 12 m Tertiary sediments are exposed, can sub- divided into four units (compare text-fig. 2). The boundary between the Sovind Marl and the chosen Brejning Clay was as zero-level. Unit 1 (minus 2.00-0.00 m) Light greenish marl, weathering almost white, with calcareous concretions in a few horizons. The is base of the unit is not exposed, so its total thickness unknown. The uppermost 0.6 m are biotur- minus 0.45 in which horizontal filled bated, especially the interval minus 0.60 to m, burrows, with a dark burrows with maximum diameterof about 2 grey clay, are numerous. Many oblique a cm are 0.10 present in the uppermost m. They are filled with sediment from unit 2 (dark sandy clay with faecal pellets and shell fragments). No macrofossils have been observed in unit 1. The marl belongs to the Sovind Marl Formation. It be the calcareous NP 16 may assigned to nannoplankton zone (E. Thomsen, Geological Institute, Arhus; pers. comm., 1986). Unit 2 (0.00-1.75 m) A 1 sharp boundary, indicating an erosional unconformity, separates units and 2. The interval is YR 0.00-0.70 m a homogenous, silty mud of dark brown colour (10 2/2). No burrows were observ- ed. At the base black size about 6 is phosphorites (maximum cm) are frequent; some glauconite pre- is sand with and sent in the sediment. The interval 0.70-0.90 m a green, strongly glauconitic pyrite Fig. 2. Stratigraphical interpretation of the Norre Vissing sequence (author: C. Beyer). material of The term “mud” is used for poorly sorted carbonaceous fine-grained consisting mainly amount distribution: silt, but with a considerable of clay and fine-grained sand (estimated grain-size The is used for sand of which 60% silt, 35% clay, 5% sand). term “glauconite” greenish grains, some might possibly be chamosite. Degree of bioturbation: the scale of Reineck & Singh (1980) is used. 197 198 overlain mud phosphorites, from 0.90 to 1.70 m by a silty with upwards increasing glauconite con- 1.75 sand is rather small and tent. From 1.70 to m a glauconitic present with phosphorites (1-2 cm) in but for the pyrite-filled burrows. Macrofossils are common unit 2, greater part irregularly from the inter- distributed in pockets. The molluscan fauna treated in this paper originates especially val 0.00-0.70 in which of Fusiturris F. enodis, F. m, large specimens e.g. Drepanocheilus speciosus, selysii, Nucula and collected. duchastelii, Orthosurcula regularis, comta Lentipecten corneus have been Especially the gastropod Drepanocheilus speciosus is often found in pocket-like concentrations. In the interval 0.70-0.90 fossils decreases m thin-shelled bivalves (e.g. Abra bosqueti) are frequent. The number of upwards, often result of in where the shells are decalcified as a pyrite oxidation, resulting a preservation as casts moulds. A of collected 1.75 or single specimen Drepanocheilus speciosus, however, was at + m. fauna is of Late The unconformable lower to The molluscan evidently Oligocene age. boundary the Eocene-Middle Sovind Marl (unit 1) thus represents a major hiatus, spanning the Late Oligocene.