The Aquatic Genus Notonecta (Insecta: Heteroptera) as a Palaeo-ecological Indicator of Rhythmite Miming Sequences in Shallow Freshwater Deposits.
Jean-Claude Paicheler , André Nel, Jean-Claude Gall, Xavier Delclòs.
Keywords: INSECTA, NOTONECTIDAE, PALAEOLAKE, VOLCANO-SEDIMENTARY, LAMINAE FORMATION, MICROBIAL MATS, OLIGO-MIOCENE, TURKEY
We study the processes of laminae formation in the Oligo-Miocene volcano-sedimentary palaeolakes of the Gürçü-Dere Valley (Anatolia, Turkey). These deposits contain a rich macro- and micro-flora and vertebrate and insect fauna. The deposition and fossilisation of these organisms' remains are related to the development of the lakes' surface and bottom microbial mats. These strata are made of two types of rhythmite or varve, imitating dark and clear laminae sequences. The first type is (detritic + organic material) / diatoms at the Bes-Konak palaeolake, probably not of seasonal origin (rhythmite), but providing evidence of short ecological 'mini-catastrophes', a few weeks long, in confined environments. The second type is (diatoms + organic matter) / dolomite at the Iybeler palaeolake, probably of seasonal origin (varve). For the first time, we show that fossil insects, i.e. the Notonecta spp., are highly relevant to determining the relative duration and mechanisms of the depositions of these laminae.