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Miocene palynomorphs from lignites of the Soma Basin (West Anatolia, Turkey)


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Title: Miocene palynomorphs from lignites of the Soma Basin (West Anatolia, Turkey)
Authors: Takahashi, Kiyoshi / Jux, Ulrich
Issue Date: 31-Jul-1991
Citation: 長崎大学教養部紀要. 自然科学篇. 1991, 32(1), p.7-165
Abstract: The intermontane Soma Basin of West Anatolia holds a key position as regards palynologic indication of its continental sequence of strata for the Miocene span of time. In pre-Neogene vales, which were framed by high mountains, a rather extensive sedimentary succession of approx. 500m was accumulated; the section is composed of fluviatile and lacustrine rocks in both clastic and calcareous facies, including, however, several coal seams (lignites). Two depositional cycles, separated by an erosional phase, are to be distinguished. During the Late Neogene volcanic events caused such drastic changes in the local relief and drainage pattern that in Soma Daglari the final stages of basin evolution no longer matched adjacent ones. In consequence of the cyclic progress in sedimentation the section was stratigraphically subdivided in Soma and Denis Formations, with subsequently correlated Turgut, Sekkoy and Yatagan Members. Meanwhile, these members have been radiometncally dated at sites near by and in other regions of West Anatolia. Accordingly, the Lower Coal Bed (KM1,2) traces back to Late Burdigalian, the Middle Coal Bed (KM3) most likely to Langhian- Serravallian and the Upper Coal Bed (KP1,2) finally to Tortonian. As the section so far includes Early, Middle and Late Miocene units, their characteristics in both facies development and structural evolution seem to correspond quite well modern ideas on the regional geology of Anatolia. A fossil microflora, rich in form species as well as individual specimens, was recognized in those samples taken from the three coal beds. This material occasioned a first comprehensive presentation of Miocene sporomorph assemblages from Soma Basin. Altogether 169 species were noted which refer to 59 form genera. A good few of these palynomorphs, their essential characteristics, stratigraphic ranges, botanical affinities and synonymous taxa being described and listed, show such a long stratigraphical and wide regional distribution that they allow no definite dating. There were, however, certain species noted which not only support a Miocene age of the sedimentary sequence with the coal seams, but also mark out Early Miocene (Burdigarian) for the Lower Coal Bed (KM1,2) and Late Miocene (Tortonian) for the Upper Coal Bed (KP1,2). The following 18 palynomorphs were recognized to be new species which accordingly had to be described with a diagnosis: Laevigatosporites turcicus n. sp., Cedripites anatolicus n. sp., C. pseudodeodaraeformis n. sp. Piceapollis anatoliensis n. sp., P. minor n. sp., Ephedripites (Ephedripites) anatolicus n. sp., E. (E.) minor n. sp., Cupuliferoidaepollenites longus n. sp., Quercoidites somaensis n. sp., Retitrescolpites globosus n. sp., Striatopollis circularis n. sp., Tricolpites tecturatus n. sp., Tricolpopollenites anatolicus n. sp., Tricolporopollenites turcianus n. sp., Momipites somaensis n. sp., Tricolporopollenites moderates n. sp., Ovoidites lanceolatus n. sp., and Schizosporis ellipsoideus n. sp. In addition to that emendation were considered to suit the following 7 species: Piceapollis neogenicus Nagy n. comb., Pityosporites baileyanus Traverse n. comb., P. miocaenicus Nagy n. comb., Tricolpopollenites robusteus Song, Li & Zhong n. comb., Compositoipollenites denizliensis Nakoman n. comb., Intrabaculitricolporites ellipsoideus Takahashi & Jux n. comb., and Nyssapollenites kruschi (Potonie) Nagy asp. pseudolaesus Potonie n. comb. The coal seams of Soma Daglari, exhibiting Early, Middle and Late Miocene sporomorph associations, serve not only as biostratigraphic markers for regional correlation of Neogene sections but also for the recognition of paleoecologic trends and paleoclimatic events. It turned out, that West Anatolia micro floras of Miocene age do reveal their own characteristics and are not easily compared with those of Central Europe. These lignites were not formed in open low land environments, instead, they arose in insufficiently drained mountain valleys from peats of boggy forests and gyttjas deposited on swampy grounds. Most likely, these marshy places were fringed by some bushwood which connected with extended areas of mixed forests along the hillsides. Proper stands of conifer trees did perhaps only flourish on top of the hills. Sporomorph associations as they were recognized in three successive horizons of the Lower Coal Bed (KM1,2) point at a gradual impoverishment of species diversities. This trend seems, however, to be reversed when the microflora of the Upper Coal Bed (KP1,2) is considered. To sum up, the mountainous area has highly influenced the composition of the fossil associations as can be concluded again and again from the pollen spectra presented. Nevertheless, disappearances and new occurrence of certain palynomorph groups as well as sporomorph species-in particular among herbs and conifers-may be taken as a prelude of the decisive climatic changes of Late Neogene.
URI: http://hdl.handle.net/10069/16623
ISSN: 02871319
Type: Departmental Bulletin Paper
Text Version: publisher
Appears in Collections:Volume 32, No. 1

Citable URI : http://hdl.handle.net/10069/16623

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