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- MakaleAçık Erişim2020Scopus SJRQ3Early Miocene seed like plant remain fossils and facies associations from the Nallıhan district (NW Turkey)
Görmüş, Muhittin; Kadioğlu, Yusuf Kağan; Varol, Baki Erdoğan; Us, Muhammed Sami
Seed like fossils recognized by their distinctive orbicular in shape are seen in the early Miocene of the Nallıhan area (NW Türkiye). We examined more than one hundred specimens and facies associations for interpreting of fossil morphology and its paleoenvironment. The fossils as dark crystallized dots on the bedding surface of clayey limestones are characterized by a thick edged lenticular shape with a smooth one side and concave another side with circular nucleus. Their internal structures have circular a few whorlings, too often radial calcitic lamellae on the upper side and a few circular coiling at the bottom side. SEM, EPMA and RAMAN data of soft nucleus, hard part, filling materials and surrounding sediments support its plant origin. The Paleogene aged Kızılbayır formation and early Miocene aged Karadoruk and Akpınar formations include the following facieses: non-channelized red sandstone and mudstone (F1), channelized “confined” reddish-beige pebbly sandstone and conglomerate (F2), medium to coarse siliciclastics (F3), mudstones interbedded with sandstones (F4), thin bedded clayey limestone bearing plant fossils (F5) medium to thick bedded limestone (F6) and rhythmic siliciclastics - clayey limestone including coal occurrences (F7). Abundant plant fossils indicate a planted shallow lake margin with low topography during the early Miocene.
- MakaleAçık Erişim2019Scopus SJRQ2Microborings as indication of cryptic life modes in the foraminifer Orbitoides: Maastrichtian sediments of the Haymana and Nallihan districts (Ankara, Turkey)
Görmüş, Muhittin; Demırcan, Huriye; Kadioğlu, Yusuf Kağan; Yağmurlu, Fuzuli; Us, Muhammed Sami
Widespread Maastrichtian siliciclastics and carbonates cropping out in the Haymana (S Ankara) and Nallihan (NW Ankara) districts in the northwest and central Anatolia basins include rich Orbitoides occurrences. Microborings in the Orbitoides tests are interesting to notify. In this study, the details of their morphologic structures were investigated. Microborings were analyzed in more than 650 equatorial thin sections of the Orbitoides tests and 100 hard rock thin sections. The abundance of microborings increases in the siliciclastics towards the Cretaceous/Palaeogene boundary (K/Pg). They were identified as Maeandropolydora osmaneliensis Nielsen and Görmüs, Maeandropolydora isp. Curvichnus semorbis Nielsen, Oichnus simplex Bromley, Oichnus isp. Maeandropolydora osmaneliensis Nielsen and Görmüs. Maeandropolydora isp., semicircular to circular microborings of Curvichnus semorbis Nielsen and Oichnus simplex Bromley are related to parasitic life modes. Irregular wider unidentified microborings are hermit type life mode tunnels. Abundance of the microborings might be related to shallower siliciclastic environmental conditions such as feeding and suitable Eh-pH, test shape, and easy entrance to the test for parasites. Smaller benthic foraminifera are seen in both microspheric and megalospheric Orbitoides tests as parasites. In conclusion, occurrences of microborings and encrustations are associated with parasitism by appearances of Maeandropolydora osmaneliensis Nielsen and Görmüs, Curvichnus semorbis Nielsen and Oichnus simplex Bromley and commensally attachment by microalgae.
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