Szabó János szerk.: Fragmenta Mineralogica Et Palaentologica 21. 2003. (Budapest, 2003)
44 DULAI, A. Tectonic disintegration of the former platform resulted in an intricate pattern of submarine horsts and inter\ r ening basins during the Sinemurian and Pliensbachian in the Bakony and the Gerecse Mts, too. Sedimentation was condensed and episodic on the horsts, but more or less continuous and thick sequences characterised the basins. Aprons of partly redeposited material, including brachiopod shells (Pisznice, and Isztimér Limestone Formations; VÖRÖS & GALÁCZ 1998; Figure 5) surround the submarine heights. All of the studied Early Sinemurian localities are from the basin areas. Localities and taxonomic composition of their brachiopod fauna Hettangian localities Kardosrét Limestone, Rich material was collected from the Kardosrét Limestone Formation ("Dachstein-type Liassic Limestone") at 13 localities of the Bakony Mountains. Eleven of them yielded identifiable fauna (Bakonybél, Kőris-hegy; Borzavár, Páskom; Kardosrét, Cuha-völgy; Kardosrét, Szesztra-hegy; Olaszfalu, Eperkés-hegy; Lókút, Lókúti-domb; Eplény, Kávás-hegy; Márkó, Som-hegy; Herend, Alsóhajag; Szentgál, Tűzköves-hegy; Városlőd, Csalános-völgy—DULAI 1993a, b). Previously, only two brachiopod species were known (MICHALIK et al. 1991) from this limestone but twelve species were distinguished in the new material. Though no ammonite has been found in the Kardosrét Limestone, on the basis of the stratigraphie position, the Hettangian age is generally accepted. Among the identified 200 brachiopods, terebratulids are prevailing (96%), rhynchonellids are rare (3%), whereas spiriferinids are insignificant (1%). (All of the percentage data of this paper refer to the number of specimens, not the number of species.) The identified brachiopod fauna is predominated by Lobothyris (92%), and 67% of the specimens belong to a single species: Lobothyris ovatissimaejormis (BÖCKH, 1874). This species is present in nearly all of the Pisznice Limestone, Tata, Kálvária-domb — The Kálvária-domb section is situated in the Tata depression (VÖRÖS & GALÁCZ 1998; Figure 4). The Kardosrét Limestone is missing from this area, and the deeper water Pisznice Limestone rests on the Upper Triassic Dachstein Limestone with unconformity. The new collections were done from the oncoidal layer just above the Triassic/Jurassic unconformity. Relatively few specimens were found but the diversity was high: 20 identified specimens represent 8 species takony Mountains studied localities with a relatively large specimen number. All other genera (Calcirhynchia, Salgirella, Liospiriferina, Phymatothyris, Zeilleria) are known in small numbers, mostly from one or two localities (Figure 2). Figure 2 — Generic composition of the brachiopod faunas at the Hettangian localities. Gerecse Mountains (DULAI 1998b). The associated ammonites indicate the upper part of the Megastoma Zone and the lower part of the Marmorea Zone (PÁLFY et al. 1998). Among the identified brachiopods, 60% are rhynchonellids, 30% terebratulids and 10% spiriferinids. The relatively frequent genera are Calcirhjnchia (20%), Cuneirhynchia (20%), Cirpa (15%) and Zeilleria (15%), others, in smaller (5-10%) proportion, are: Salgirella, Liospinferina, Lobothyris, Phymatothyris, Bakonyithyris (Figure 2). Early Sinemurian localities Pisznice Limestone, Lókút, Lókúti-domb — This locality is situated in the Lókút Basin between the Hajag-Papod and Amos horsts (VÖRÖS & GALÁCZ 1998, Figure 5). The Lower Sinemurian Pisznice limestone rests unconformably on the Hettangian Kardosrét Limestone. Four intervals were collected bed-by-bed (DULAI 1990). On the basis of 400 identifiable specimens, 29 brachiopod species were distinguished (DULAI 1992). Ammonites occurred only in the upper part of the section and they indicate the Arietites bucklandi Zone of the Early Sinemurian (GÉCZY B. pers. com., DULAI 1990). Bakony Mountains Among the identifiable brachiopods, terebratulids are prevailing (44%) but rhynchonellids and spiriferinids are also common (29% and 27%, respectively). Liospiriferina and Zeilleria predominate the fauna at the generic level (25-25 %, respectively). Group of the less frequent but common taxa includes Securina (15%), Cuneirhynchia (12%) and Caldrhynchia (10%). All the other genera are present in small numbers (Rljynchonellina, Prionorhynchia, Cirpa, Callospiriferina, Dispiriferina, Lobothyris, Linguithyris, Phymatothyris, Antiptychina, Bakonyithyris) (Figure 3).
