Early Valanginian brachiopods from the Mecsek Mts. (southern Hungary) and their palaeobiogeographical significance

Abstract

Limestone layers settled on altered pillow lava and hyaloclastite at the tiny iron ore-mine near Zengővárkony (Mecsek Mts., southern Hungary) yielded remarkably large and rich brachiopod-dominated fauna representing Lacunosella hoheneggeri (SUESS), Moutonithyris sp. aff. moutoniana (D'ORBIGNY), Karadagithyris sp., Nucleata veronica NEKVASILOVÁ and Zittelina pinguicula (ZITTEL) taxa. Re-sampling of the Neocomian outcrop of Kisújbánya also yielded a rich fauna representing Lacunosella hoheneggeri (SUESS), Lacunosella ?spoliata (SUESS), Lamellaerhynchia multiformis (ROEMER), Pygites diphyoides (D'ORBIGNY), and Nucleata veronica NEKVASILOVÁ. Taxonomic description and internal morphology based on serial sectioning are reported for the first time from the Early Cretaceous beds of Mecsek Mts. Age of the sequences is Early Valanginian (Thurmanniceras pertransiens Zone), which is in fine correlation with parastratigraphic results on tintinnids (Calpionellites darderi Zone). Size distribution of brachiopod specimens refers to nutrient environment, which would have been in connection and related to the Early Cretaceous volcanism, and the iron-ore formation. Palaeobiogeographically, the fauna strongly indicates a Tethyan origin of Mediterranean character being supported for the first time by brachiopod data and being in fine correlation with earlier palaeobiogeographic analysis on ammonites. This fauna shows strong connection to the brachiopod faunas of the Western Carpathians. Zusammenfassung: Fossilreiche Kalke über hyaloklastischen Vulkaniten bei einer kleinen Eisenerzgrube nahe Zengővárkony (Mecsekgebirge, südliches Ungarn) enthalten eine artenreiche Brachiopodenfauna mit folgenden Arten: Lacunosella hoheneggeri (SUESS), Moutonithyris sp. aff. moutoniana (D'ORBIGNY), Karadagithyris sp., Nucleata veronica NEKVASILOVÁ und Zittelina pinguicula (ZITTEL).

A unique Valanginian paleoenvironment at an iron ore deposit near Zengõvárkony (Mecsek Mts, South Hungary), and a possible genetic model

“…The asterisk indicates the examined outcrop but the 0.5-5 cm thick hyaloclastite crust and close to that its amygdaloidal structure (with vesicles 0.3-3 mm in diameter) is remarkable. The fauna is concentrated close to the lava surface, being allochthonous and strongly redeposited, dominated by strikingly large-sized brachiopods and fragmented ammonites (Bujtor 2006). The dominant component is the brachiopod fauna; all other faunal elements (cephalopods, gastropods, echinoderms) are subordinate.…”

“…Palik 1965) and the shallow-water indicator Lacunosella (Krobicki 1994: Krobicki andWierzbowski 1996), appearing in great quantities and remarkably large size (cf. Bujtor 2006), all point to one possible environment: a hydrothermal vent. Stable isotope analyses unequivocally ruled out the cold seep origin.…”

“…He noted that this species is known from both shallow-water, reeflike carbonate deposits and olistoliths in the Polish Outer Carpathians, where it represents nearly 80% of the entire brachiopod assemblage. It is very remarkable that in Zengõvárkony, L. hoheneggeri represents 61% of the brachiopod assemblage (Bujtor 2006). Krobicki (1994) also highlighted that this species is typical for the sublittoral zone and abundant in the Štramberk-type (reef-like) carbonates.…”

“…from the tailings of the ore mine. More recently Bujtor (2006) reported Valanginian brachiopods from Zengõvárkony revealing a strong faunal connection to the Pieniny Klippen Belt of the Western Carpathians, and presenting the first faunal evidence from the Mecsek Mts for the common development of the Tisza Unit and the Carpathians, already established through plate tectonics (cf. Golonka and Krobicki 2004;Haas and Péró 2004;Golonka et al 2005).…”

“…According to Palik (1965, p. 99) the crustacean excrements (present in great quantities in the iron ore) may have played a considerable role in the formation of the iron ore of Zengõvárkony. Bujtor (2006) pointed out that the most abundant faunal elements are the remarkably large-sized specimens of Lacunosella and Nucleata. Krobicki (1994) noted that L. hoheneggeri in the Polish Outer Carpathians is typical for the sublittoral zone.…”