Type of Culminating Activity
Doctor of Philosophy in Geosciences
Mark D. Schmitz
The continuous Pennsylvanian shallow-marine, paralic, siliciclastic succession in the Donets Basin is pivotal for correlation of marine and continental strata in northern Pangaea with coeval shallow-marine mainly carbonate strata in the Moscow Basin, a historical type area of Moscovian Horizons. The details of the history of establishment, lithostratigraphy and current biostratigraphy of Podolskian and Myachkovian Horizons in the Moscow Basin that are not readily available in Western literature are reviewed.
A model of cyclic recurrence (~0.6 —1myr) of three main fusulinid assemblages in the Pennsylvanian siliciclastic-carbonate succession in the Donets Basin is proposed. A Hemifusulina-association (A) indicates the onset of transgression (ETST: early transgressive system tract); maximum transgression (LTST-EHST: late transgressive – early high-stand system tract) is characterized by the Beedeina–Neostaffella–Ozawainella–Taitzehoella (or Beedeina-dominated) assemblage (B), which is successively replaced by the most diverse Fusulinella-dominated association (C) in a progressively shallowing sea (LHST-ELST: late high stand – early low stand system tracts).
Our proposed model offers refinement of the regional biostratigraphy and permits robust interbasinal correlation of Pennsylvanian-age Tethyan successions based on the Beedeina-dominated association, which marks maximum transgressions during the Pennsylvanian. Fusulinids, occurring in the regressive part of each cycle, are the most provincial and are therefore the most useful for making paleogeographic reconstructions. Specifically, they can be used for recognition of originally contiguous regions that later may have been dispersed hundreds or thousands of kilometers. The model also provides a better understanding of an extinction event at the Moscovian – Kasimovian transition that involved many fusulinid genera inhabiting predominately deeper and colder water environments of transgressive seas. Various combinations of the proposed assemblages record ‘symmetrical’ and ‘asymmetrical’ distributional patterns and are capable of delineating the evolution of basins in different tectonic settings.
Application of a proposed model in the Podolskian and Myachkovian biostratigraphy and correlation is tested. A new integrated biostratigraphic and sequence stratigraphic approach for a biozone definition in the Donets Basin is proposed. Fusulinid biozones are acme or assemblage zones in which an abundant occurrence of the index and associated species is related to relative sea-level change and therefore the bases and tops of proposed zones are bound with unconformities, erosional surfaces or soil formations.
Three fusulinid cycles are recognized in the “M” Formation of the Donets Basin, Ukraine. One of the cycles includes limestone M7–M101. Fusulinids distribution reveals transgressive beds (limestones M7 – M8) and high stand – regressive beds (limestone M9 – M101). A Hemifusulina subrhomboides – H. vozhgalica – Beedeina elshanica vaskensis Zone is proposed for the transgressive limestones. Within transgressive limestones two subzones are defined. The lower Hemifusulina vozhgalica – Hemifusulina subrhomboides Subzone (limestones M7 and M7up) is coeval with the middle part of the Smedva Formation in the Moscow Basin, which currently belongs to the Upper Kashirian. The Beedeina elshanica vaskensis Subzone (limestones M72 and M8) is correlated with the upper part of the Smedva Formation. High stand – regressive beds are subdivided into two zones. The Putrella donetziana – Fusulinella colanii Zone (limestone M9) is coeval with the Vaskino Formation (lower Podolskian). The Kamaina rossoshanica – Fusulinella tokmovensis longa Zone (limestone M10) is provisionally correlated with the Ulitino Formation (middle Podolskian). The analysis of cyclic distributional patterns of fusulinids suggests that the Kashirian-Podolskian boundary should be placed according to its historical position, at the base of the local Smedva Formation. The boundary between Podolskian and Myachkovian in the Donets Basin is unclear, additional material is needed to define the boundary in this region.
A fusulinid taxonomic study of the Gurkovo and Kalinovo sections allows us to refine the biostratigraphy of the poorly studied Myachkovian (Upper Moscovian) strata of the “N” Formation in the Donets Basin. Three fusulinid biozones, Hemifusulina graciosa – Fusiella spatiosa, Fusulina cylindrica – Fusulinella pseudobocki, and Fusulinella (?) kumpani, are proposed in the interval from the top of Limestone M10 to the base of N3, and they are correlated with coeval strata in the historical type area of the Moscow Basin. A total of 33 fusulinid species and subspecies belonging to 8 genera are described, including three new species: Hemifusulina gurkovensis n. sp., Beedeina innaeformis n. sp., and Fusulina sosninae n. sp. The main evolutionary trend in fusulinid morphology in the late Moscovian is the appearance of massive secondary deposits in the limestone of the “N” Formation.
The similarity of fusulinid assemblages in the Moscow and Donets Basins and their cognate evolution trends reveal a connection between both regions at least during Podolskian – Myachkovian time.
Khodjanyazova, Rimma, "Cyclic Distributional Model of the Late Moscovian Fusulinids in the Donets Basin (Ukraine) in Response to Eustatic Sea Level Fluctuations and Its Application in Biostratigraphy and Correlation" (2013). Boise State University Theses and Dissertations. 745.