Early Miocene seed like plant remain fossils and facies associations from the Nallıhan district (NW Turkey)

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.