Come Back on Facies Characteristic and Diversity in Carbonate Eolian Dunes

Frébourg, Gregory¹, Claude-Alain Hasler¹, Pierre Le Guern², Eric Davaud¹ (1) University of Geneva, Geneva, Switzerland (2) Schlumberger, Stavanger, Norway

Carbonate eolian dune belts can reach huge sizes in coastal areas and may represent potential reservoirs. However, these deposits are seldom described, except for the Permo-Carboniferous and the Quaternary times. They are otherwise either rare or non-present because of palaeogeographic or palaeoclimatic factors, or we lack adequate recognition criteria.

These deposits are formed by material from the deflation of beach deposits and marine sediments when exposed during eustatic variations. It is commonly agreed that eolian deposits are fine grained and laminated.

Pleistocene, Holocene and modern carbonate dunes observed in southern and western Australia and in the Mediterranean area display a broad range of facies, grain sizes, and textures. Most surprising are the good to excellent foraminifer test preservation, the high faunal diversity assemblages and in some cases the abundance of planctonic foraminifera. On the other hand, only a few samples show at the core or thin section scale, the fine grained and laminated combination or pedogenetic and vadose imprints.

This study reviews the variety of carbonate eolian facies in order to provide better recognition tools at the core and thin-section scale. Recognition is important because of their good reservoir potential of these deposits and their value as sequence-stratigraphic markers.