FRAGMENTA PALAEONTOLOGICA HUNGARICA 21, BUDAPEST, 2003 Early Jurassic fauna and facies of the Schafberg area (Salzkammergut, Austria) by Attila VÖRÖS, János SZABÓ, Alfréd DULAI, István SZENTÉ, Oskar EBLI «Sc Harald LOBITZER Abstract — In order of a complex reexamination of the Jurassic faunas of the Schafberg and closely connected area, the authors carried out new collecing and sampling. The studied area contains localities of classical palaeontological monographs, based on fossils of the Lower Liassic Mierlatz Formation and some other associated limestones. During the field work we attempted to locate the classical sites but most of the exposures are new. Characteristic megafossils are the brachiopods but bivalves and gastropods are also found. Beside notices on the microfacies and microfossils, the identified species of the faunas are listed below, and, some palaeontological remarks are added to most of the listed species. The faunal lists are partly completed with museum materials. Keywords — Early Jurassic, microfacies, bivalves, gastropods, brachiopods VÖRÖS, A., SZABÓ, J., DULAI, A., SZENTÉ, I., EBLI, O. & LOBITZER, H. (2003): Early Jurassic fauna and facies of the Schafberg area (Salzkammer- gut, Austria). — Fragmenta Palaeontologica Hungarica, 21: 51—82. Introduction Mt Schafberg belongs to the classical areas of Liassic SPENGLER (1911), who had been WÄHNER'S student, research in the Northern Calcareous Alps and several published the most comprehensive description of the monographies dating back to the 19th century deal with geology of Schafberg, situated within the "Schafberg- the rich mega- and microfauna from various lithologies. Tirolikum" tectonic unit. SPENGLER initiated also the The first comprehensive description of the rich mega- first microfacies study of the Schafberg region by fauna of the Hierlatz Limestone we owe to HAUER (1853, LEISCHNER (1969). From the tectonic point of view, also 1855) who already mentioned ammonites and brachiopods the paper by HAHN (1913) is important. in the light reddish and whitish limestones in the higher The complex tectonic situation of Mt Schafberg is well regions of Schafberg. OPPEL (1861), BlTTNER (1893) and explained by PLÖCHINGER (1973). In principle, the upper BÖSE (1877) dealt with the brachiopod fauna in more part of Schafberg is represented by a synclinc, which is details, while GEYER (1893) described the ammonites and overturned towards the North. Looking from the North to STOLICZKA (1861) studied the gastropods and the bivalves. the northern wall of Mt Schafberg, we face Upper Jurassic OPPEL assumed, based on findings of ammonites, that the radiolarite in the core of the syncline, which is underlain Hierlatz Limestone of the Schafberg is of Lower Liassic age, by red Middle Liassic Adnet type limestones and by Hierlatz while STOLICZKA'S studies pointed to Middle Liassic. In limestone, which is well exposed also on the top of Mt 1862 MOJSISOVICS paid a short visit to Mt Schafberg and Schafberg. The area may be divided into two main tectono- argued that OPPEL is right in the age of the ammonite- sedimentary units, separated by a large-scale overthrust at bearing basal dark red limestone. However, he regarded the the northern foot of the Schafberg, recognized and named higher part of the gastropod-bearing dark red limestone and by SPENGLER (1911) as "Grünsee Überschiebung" or the overlying brachiopod-dominated Hierlatz Limestone s.s. "Grünseescherfläche" (PLÖCHINGER 1973). as Middle Liassic. STUR (1871) reports a faunule consisting of The upper unit forms the bulk of the Schafberg, consis­ ammonites, bivalves and brachiopods from bright red ting chiefly of Hierlatz limestones of extremely big thick­ limestones of the Grünsee locality. In his classical paper on ness and grey, siliceous limestones of Lower Jurassic (mainly the facies differentiarion of various Liassic limestones of the Sinemurian) age. The Hierlatz limestones are exposed on Northern Calcareous Alps, WÄHNER (1886) considered the the top and on the southern slope of Schafberg in the light-red cephalopod-rich limestones of the "Hinter-Schaf- form of thick, not well-defined beds dipping roughly con­ berg" an equivalent of the horizon of Amaltheus margaritatus. cordant with the slope. It represents the "bed-like" type From facies point of view WÄHNER regarded these variega­ of VÖRÖS (1991) and can be interpreted as a wide belt of ted cephalopod limestones as transitional development submarine, biodetrital talus of 200-300 m thickness. The between the brachiopod-crinoid-gastropod-rich Hierlatz source area of the biodetrital material may be sought Limestone and the true Adnet Limestone. The sponges, toward the North, near or beyond die peak region of Schaf­ radiolarians and foraminifers of the "Uas-Kieselkalk" were berg, whereas the interfingering with more distal, basin described by DUNIKOWSKI (1882). On the occasion of the sediments can be found nearly one km far to the South IXth International Geological Congress in Vienna in the (e. g. at Schafbergalpe). year 1903, WÄHNER summarized his rich knowledge on The lower unit is exposed in a narrow belt along the that region in an excursion guide booklet of the Schafberg. northern foot of Schafberg and consists of Upper Triassic "Plattenkalk", and red crinoidal-brachiopodal limestones the authors during joint field-trips in June 2000, June 2001 (with BÖSE's fauna, Middle Lias). The recent geological maps and July 2002. We visited some outcrops at Schwarzensee (PLÖCHINGER 1973, 1989), show that the red, crinoidal (near Aschergraben, Grafenalm and Meislalm); the peak limestones form separate, narrow belts on the northern side region of Schafberg; the cliffs and "kars" around Mönichsee of Schafberg, apparendy without direct sedimentary contact and Mittersee (at the northern feet of Schafberg, between to the Lower Liassic Hierlatz limestones. According to our Spinnerin and Törlspitz); and the northern slope of Eiben­ observations, around the Mitterscc, the very gentiy dipping, berg (above the lake Mondsee) (see Figure 1). thick banks of the "Plattenkalk" are cut by two or three, The collected fossils and samples were divided amongst great, parallel, vertical neptunian dykes, exceeding 10 m in the participants to study: microfacies and microfauna — width. The strike of the dykes is roughly parallel with the O. EBLI, bivalves — I. SZENTE; gastropods —J. SZABÓ; northern wall of the Schafberg (WNW to ESE). Sinemurian (Hierlatz Limestone s.s.) brachiopods — A. The previous palaeontological descriptions have sugges­ DU LAI; Pliensbachian brachiopods — A. VÖRÖS. ted that the Lower Jurassic faunas of Schafberg are very In the foUowing, we give short description and evalua­ similar to those of the Bakony Mts (Hungary). This similarity tion of the microfacies types and present lists of the identi­ was aimed to study by in situ coUecting work, carried out by fied fossils, with some taxonomical remarks. Figure 1 — Localities of the new collections. — Numbers indicate groups of collecting points close to each other Explanation to Plate I 1 Microfacies la — Crinoidal-biomicrite to sparite (wacke- to packstone). The often abraded crinoidal remains are mosdy surrounded by svntaxial rim-cements. — Sample SBB 2, x6. 2—3 Microfacies 2 — Filament-crinoid-biomicrite (wacke- to packstone). Besides the characteristic "filaments" (debris of thin-shelled bivalves, possibly Posidonia alpind), there occurs in Plate I: 2 a bryozoan fragment, that is impregnated on its top with a thick phosphatic crust, whereas sample MS 1 (Plate I: 3) is rich in small phosphatic and Fc/Mn-nodules. — 2: Sample SBM 7, x8; 3: Sample MS 1, XlO. 4—5 Microfacies 3 — Ostracod-echinoderm-biomicrite (wacke- to packstone). Besides the characteristic thick-shelled ostracods (e. g. 4. top) and miliolid foraminifera, sometimes also stromatactis-like features can be recognized (5). — 4: Sample SBM 2, Xl7; 5: Sample SBB 150-1, x8. 6—7 Microfacies 4 — Echinoderm-spicula-biomicrite with forams and ostracodes. Besides spicula (6), there often occur up to several cm large sponges (7), with the osculum filled by peloidal sediment and circular cements. — 6-7: Sample MA 1; 6 = x8, 7 = X 23. 8 Microfacies 2 and 5. — The lower part of the picture exhibits filamentous sediment, containing juvenile ammonites and a burrow (B) in contact to MF-5. This irregular contact is modified by pressure solution as indicated by leached crinoidal fragments (straight above "B") and a small residual layer, not visible at this magnification. — Sample MS 2, XlO. VÖRÖS, A., SZABÓ, J., DULAI, A., SZENTÉ, L, EBLI, O. & LOBITZER, H. Microfacies and microfaima The lithologies of the samples collected at the Schaf­ tation-regime at this area during Liassic times. Besides berg summit, at Mitteralm, Meisl- and Mühlaueralm are crinoidal limestones and strongly condensed facies-types, inhomogenous and reveal a very differentiated sedimen­ there occur basinal sediments with intercalated resediments. Hierlatz Limestone Microfacies la: Crinoidal-biornicrite to sparite (wacke- type. In sample SBB 2, additional spicula (below 5%) to packstone) (Plate I: 1) — Densely packed, often and rare foraminifera [Involutina liasska (JONES), Reophax abraded crinoids (30-60%) and mostly broken brachio­ sp.] occur. The predominant micritic matrix is replaced pod shells (up to 20%) are the main biota in this rock- in many places by syntaxial rim-cements. "Adnet-Type" Limestone Microfacies lb: Crinoidal-biornicrite to sparite with Besides the foraminifera-fauna mentioned above,