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

Abstract

Seed like fossils recognized by their distinctive orbicular in shape are seen in the early Mioceneof the Nallıhan area (NW Türkiye). We examined more than one hundred specimens and faciesassociations for interpreting of fossil morphology and its paleoenvironment. The fossils as darkcrystallized dots on the bedding surface of clayey limestones are characterized by a thick edgedlenticular shape with a smooth one side and concave another side with circular nucleus. Theirinternal structures have circular a few whorlings, too often radial calcitic lamellae on the upperside 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 Paleogeneaged Kızılbayır formation and early Miocene aged Karadoruk and Akpınar formations includethe 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 includingcoal occurrences (F7). Abundant plant fossils indicate a planted shallow lake margin with lowtopography during the early Miocene.