Izmirella cretacea nov. gen., nov. sp., a complex alga from the Lower Cretaceous, NE of Bornova-Izmir/Turkey

Abstract

Izmirella cretacea nov. gen., nov. sp., a complex alga, forming microbioherms is described from Barremian - Aptian platform carbonates of the "Bornova block", an allodapic unit derived from the northern margin of the Menderes Massif, included in Maastrichian - Danian flysh deposits, the so called "Bornova melange". The verticillate thallus of this alga consists of strongly imbricated bowl- to funnel-shaped whorls having tightly stacked laterals with two layers. The first is composed of radially and fan-like running segments, appearing as large cells in section parallel to the growth direction. The second is composed of multibranched tubes, running perpendicular to the segments of the first layer. Besides its organizational traits, this has original calcite mineralogy and an aggregative behaviour leading to the formation of laminated buildups closely resembling stromatolitic bioconstructions or even stromatoporoids.