DILL, H.G. ,  BOTZ, R. , BERNER,  Z.,  STÜBEN, D., NASIR, S. and  AL-SAAD, H. (2005) Sedimentary facies, mineralogy and  geochemistry of the sulphate-bearing Miocene Dam Formation in Qatar.- Sedimentary Geology, 174: 63-96

Abstract: The Miocene deposits of the Dam Formation were deposited in a narrow seaway stretching along the western edge of the Qatar Arch. During the initial stages of basin evolution the rising Zagros Mts. delivered debris in this fore deep basin. The paleocurrent and paleogeographic zonation are reflected by the heavy mineral assemblage, by the spatial distribution of phyllosilicates and the various types of sulphate. From NW towards the SE, the contents of smectite and palygorskite increase, whereas the illite and kaolinite contents decrease. Mega crystals of gypsum are found in the NW and massive fine-grained gypsum in the SE. During the waning stages of the Miocene basin subsidence, the Arabian Shield became more and more important as a source for the Miocene sediments. In this study, the Dam Formation was subdivided into 7 members/lithofacies associations (lower, middle, upper Salwa and Al Nakhsh Members, Abu Samrah Member). The Salwa Members at the base of the Dam Formation consists of heterolithic siliciclastic-calcareous sediments which were laid down under meso- to microtidal conditions. The Al Nakhsh Members formed under macrotidal conditions with sub- to supratidal depositional environments passing into continental ones. Precipitation of dolomite, celestite and gypsum in these sabkha sediments was as intensive as it was the growth of microbial mats (stromatolites). Both, crystals of gypsum and the thickness of stromatolites tremendously increase towards younger sediments thereby indicating a close genetic link between growth of microbial domes and gypsum precipitation. Throughout the Abu Samrah Member marine calcareous sediments were deposited in a microtidal wave-dominated environment. Dissolution of Eocene evaporites at depth governed the lithofacies differentiation in the Miocene Dam Formation.