EGU General Assembly 2016, Vienna

Recent progress of Project CLEAR was presented during the European Geoscience Union General Assembly 2016 (17-22 April) in Vienna.

During the session “New insights in past African and Middle Eastern climates: A tribute to Françoise Gasse (CL1.16)”, Ina Neugebauer compiled new data on her TOC, CaCO3, C/N, d18O, d13C, d13C (carbonates and organic fraction), and d15N measurements from the mastercore of the Tayma palaeolake on the poster “The early Holocene humid period in the Tayma palaeolake, NW Arabian Peninsula – A high-resolution micro-facies and geochemical approach“. The data cover the stratigraphic section of c. 8500 to 8000 cal yrs. BP which is anticipated to represent the peak moisture phase during the early to mid-Holocene pluvial phase around Tayma. Ina identifies three different sub-stages: (i) aragonitic-organic varves (c. 8500 to 8300 cal. yrs BP), (ii) diatom-organic varves (c. 8300 to 8100 cal. yrs BP), frequently incorporating aragonite laminae as well as some gastropod and ostracod shells, and (iii) organic varves (c. 8100 to 8000 cal. yrs BP) with lower abundance of diatom and aragonite laminae and an increase of gypsum layers, likely heralding drier conditions.

In the same session, Anna Pint provided insights in the state of ostracod and foram analyses of the palaeo-lake deposits on her poster Ostracoda and Foraminifera associated with macrofauna of marginal marine origin in continental sabkha sediments of Tayma (NW Saudi Arabia). After an providing an overview on the microfuanal taxa representing the lake phase, Anna demonstrates how the morphology and chemistry of ostracod shells leads to quantitative reconstructions of the water chemistry.

During the session “Sediment archives and landscape evolution in dryland areas: New approaches, perspectives and challenges (GM3.4/CL1.27/HS11.11/SSS3.9)”, preliminary results of the shoreline mapping survey conducted in December 2015 were presented on the poster “Barnacles Tell no Lies – Bioclastic deposits and in-situ balanid colonies delineate shorelines of the Holocene palaeolake at Tayma (NW Saudi Arabia)“. In order to further substantiate the hypothesis that the early to mid-Holocene aquatic environment of Tayma can be categorized as a perennial lake – a view recently challenged in literature – a clear documentation of a variety of shoreline indicators (in-situ populations of the barnacle Amphibalanus amphitrite, in-situ or parautochthonous shell detritus in varying thickness) was provided.

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