Palynomorph, Foraminifera, and Calcareous Nannoplankton Biostratigraphy of Oligo–Miocene Sediments in the Muş Basin, Eastern Anatolia, Turkey

Turkish Journal of Earth Sciences

RECEP HAYRETTİN SANCAY¹ 

关键词: Oligocene;    Miocene;    Eastern Anatolia;    palynomorphs;    planktonic foraminifera;    benthic foraminifera;    nannoplankton;    palaeoenvironment;    palaeoclimate;   

学科分类：地球科学(综合)

来源: Scientific and Technical Research Council of Turkey - TUBITAK

【 摘 要 】

Oligo-Miocene sediments have not been adequately studied biostratigraphically, and a detailed bio-chronostratigraphic framework has not yet been established in Eastern Anatolian basins. Palynomorphs have therefore been correlated with the biozonations of marine dinoflagellates, planktonic foraminifera and calcareous nannoplankton of similar latitudes in combined samples from the Ebulbahar and Kelereşdere measured stratigraphic sections, which are located in the northeastern part of Muş. Palynological (dinoflagellate), foraminiferal micropalaentological, and nannopalaeontological events, correlatable with worldwide defined biozonations, have been documented from uppermost Rupelian to Upper Miocene-Pliocene sediments. First occurrences (FOs) and and last occurrences (LOs) of selected dinoflagellates are important in establishing the biostratigraphic framework. The LO of Wetzeliella gochtii in the latest Rupelian, the LO of Deflandrea phosphoritica in the latest Chattian, peak occurrences of Chiropteridium spp. in the early and late Aquitanian, the FO of Hystrichosphaeropsis obscura, followed by the FO of Membranilarnacea? picena in the late Aquitanian are of particular significance for regional correlations. Based on established marine zonations and the presence of characteristic Oligocene taxa such as Slowakipollenites hipophäeoides and Mediocolpopollis compactus, stratigraphic ranges of relatively less known pollen taxa in the region, especially those of Compositae (tubuliflorae-type), Umbelliferae, Gramineae, considered to have their first occurrences at the beginning of Neogene in earlier studies, have been calibrated. In the light of this study, the Late Oligocene-Early Miocene zonation of some palynomorphs should be emended and the stratigraphic ranges of the Compositae (tubuliflorae-type), Umbelliferae, Gramineae pollen should be extended into the Chattian and even the Rupelian in this region. As far as depositional conditions are concerned, palynomorph and organic facies properties indicate deposition under brackish water, shallow (restricted) and relatively deeper marine conditions related to fluctuating sea level during the Oligocene and Early Miocene. Shallowing-upwards deposition during the Late Oligocene was followed by restricted marine and brackish conditions at the Oligocene-Miocene boundary and in the early Aquitanian. Relatively deeper conditions in the late Aquitanian continued as extensive reef accumulations due to shallowing in the early Burdigalian. Finally, after the last deepening event at the end of Burdigalian and ?early Langian, completely terrestrial (lacustrine and fluvial) deposition predominated in the Muş Basin due to withdrawal of the sea. Terrestrial palynomorphs reflect temperate to subtropical climates in which mean annual temperatures vary between 15.6 and 21.3 °C, and mean temperatures of the coldest month (CMT) were between 5.0 and 13.3 °C.

【 授权许可】

Unknown