Matheronia

MASSE, JEAN-PIERRE, FENERCI-MASSE, MUKERREM & BUCUR, IOAN I., 2024, New Species Of The Lower Cretaceous Genus Matheronia Munier-Chalmas (Bivalve Hippuritida) In Romania, Acta Palaeontologica Romaniae 20 (1), pp. 3-15 : 3-5

MATHERONIA BEARING BEDS IN ROMANIA

The Matheronia bearing samples were collected from two regions of the Romanian Carpathians ( Fig. 1 ): Reşita- Moldova Nouă Zone in the Southern Carpathians (SW Romania), and Pădurea Craiului area in the Apuseni Mountains (NW Romania).

In the Reşiţa- Moldova Nouă area, the onset of the Lower Cretaceous ( Bucur, 1997) starts with the Lower Berriasian, represented by the Marila Limestones, and the Upper Berriasian-Lower Valanginian by the Crivina Marls, both formations corresponding to basinal deposits

1 Aix-Marseille University, Place Victor Hugo. 13331 Marseille Cedex 03, France, [e-mail] 3 2 Babeş- Bolyai University, Department of Geology and Center for integrated geological studies, Str. M. Kogalniceanu 1, 400084 Cluj-Napoca, Romania.

with calpionellids and ammonites. The Valea Lindinei Limestones (upper Valanginian-Hauterivian), make the transition from the basinal to the overlying shallow carbonate platform deposits. The corresponding Urgonian beds ( Fig. 2a ) includes the Valea Nerei Limestone Member, which consists of bioclastic limestone, sometimes with corals, chaetetids and rudists, i.e. Pachytraga carpathica Masse et al. ( Masse et al., 2023) and Matheronia dacica sp. nov. The micropaleontogical assemblage of orbitolinid foraminifera and dasycladale algae: Moulladella jourdanensis , Cribellopsis thieuloyi and Salpingoporella muehlbergii , documents the Lower Barremian ( Bucur, 1997).

The overlying Valea Minişului Limestone Formation ( Fig. 2a ) consists of bioclastic limestones, with marly intercalations. The orbitolinid association is twofold: the lower assemblage consists of Paracoskinolina maynci , Montseciella? arabica , Palorbitolina lenticularis and Praeorbitolina cormyi , of late Barremian – early Aptian age, these beds yield Matheronia nerae sp. nov. and Matheronia carinata sp. nov. The content of the upper assemblage, Mesorbitolina parva , Mesorbitolina texana and radiolitids, indicates a late Aptian age; the overlying Golumbu sandstones may belong to the “Clansayesian” ( Bucur, 1997).

In the Pădurea Craiului Mountains, the Lower Cretaceous deposits start with bauxitic rocks, followed by micritic lacustrine-paludary limestones, i.e. the Dobreşti Member of the Blid Formation, of Berriasian-Hauterivian pro parte age ( Bucur, 2000; Cociuba, 2000) ( Fig. 2b ). The upper member of the Blid Formation, i.e. the Coposeni Member, consists of micritic-fenestral and bioclastic limestone, with rudists including Matheronia dacica sp. nov. Foraminifera and calcareous algae Pfenderina globosa , Moulladella jourdanensis , Salpingoporella genevensis , S. melitae , S. muehlbergii , document an early Barremian age. In its upper part, the Coposeni Member contains Palorbitolina lenticularis , so that the overall age of the Coposeni deposits is Hauterivian pro parte – Barremian.

New species of the Lower Cretaceous genus Matheronia Munier-Chalmas (Bivalve Hippuritida ) in Romania

The succession continues with the Ecleja Formation, its carbonate upper part, the Bobdei Valley Limestone Member contains Palorbitolina lenticularis, Akcaya capitata, Paracoskinolina maynci and Salpingoporella popgrigorei , an association that suggests a possible early Aptian age. The Ecleja formation is covered by the Măgurii Valley Limestone Formation with rudists including Matheronia silvaeregis sp. nov., Lovetchenia , Horiopleura and caprinids. The associated Orbitolinidae : Palorbitolina lenticularis , Orbitolinopsis cuvillieri , O. kiliani , O. buccifer , and O. pygmaea , document an early Aptian age ( Cociuba, 2000). This dating is corroborated by the age of the overlying marls, characterized by Dufrenoya , a late early Aptian ammonite.

Figures

Fig. 1a. Geographic distribution of Lower Cretaceous rudist bearing localities in Romania, with location of Matheronia beds. b. Geological map of the Nera valley area (Reşiţa-Moldova Nouă zone). c. Geological map of the Cornet area (Pădurea Craiului). d. Geological map of the area north of Dobreşti (Pădurea Craiului).

Fig. 2. Stratigraphic logs of Lower Cretaceous successions with position of Matheronia bearing beds. a. Nera valley area (Reşiţa-Moldova Nouă zone). b. Cornet and north Dobreşti areas (Pădurea Craiului).