105 Paicheler et al. Article JTa058. All rights reserved. The Aquatic Genus Notonecta (Insecta: Heteroptera) as a Palaeo-ecological Indicator of Rhythmite Miming Sequences in Shallow Freshwater Deposits Jean-Claude Paicheler Groupe d’étude sur les Géomatériaux et Environnements Naturels et Anthropiques, E.A. 3795, 2 Esplanade Roland Garros, F-51100 Reims, France André Nel CNRS UMR 5202, Muséum National d'Histoire Naturelle, CP 50, Entomologie, 45 rue Buffon, F-75005 Paris, France Jean-Claude Gall Laboratoire de Paléontologie et de Sédimentologie, Institut de Géologie, 1 rue Bleissig, F- 67084, Strasbourg Cedex, France Xavier Delclòs* Departament d’Estratigrafia, Paleontologia i Geociències marines, Facultat de Geologia, Universitat de Barcelona, E–08071, Barcelona, Spain Journal of Taphonomy 5 (3) (2007), 105-120. Manuscript received 27 December 2006, revised manuscript accepted 23 March 2007. 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. * E-mail: xdelclos@ub.edu 2007 Journal of Taphonomy PROMETHEUS PRESS/PALAEONTOLOGICAL NETWORK FOUNDATION (TERUEL) VOLUME 5 (ISSUE 3) Available online at www.journaltaphonomy.com