Quantification of Carbonate Ramp Sedimentation and Progradation Rates for the Late Holocene Abu Dhabi Shoreline--Discussion

Abstract

The efforts of Lokier and Steuber (2008) to provide some further data on the Abu Dhabi sabkha is to be welcomed. This wonderful modern environment of carbonate–evaporite deposition produced, when first described, such a great effect on the interpretation of evaporitic sequences in the stratigraphic record, in large part due to the persuasive writings and lectures of D.J. Shearman (1966). However, there are several comments that need to be made on this manuscript. It is surprising that the authors have neither shown nor considered how their sampling line relates to the deflated beach ridges, which, together with the band of early Holocene marine sediment that occurs behind them, mark the effective limit of the Holocene marine transgression and are well developed in the area (Kirkham 1997). Furthermore, it is curious that they show their sampling sites to be located in the intertidal zone although the sediments contain anhydrite. Earlier workers showed that, although anhydrite may occur in small quantities in the sediments of the upper part of the intertidal zone, it only becomes an important constituent at approximately high-water spring tide in the zone best known as the supratidal zone, i.e., a zone which is affected by tides but is only rarely covered when the tidal heights are increased due to abnormal meteorological conditions such strong Shamal winds in this area (Evans et al. 1969; Kinsman and Park 1976; Patterson and Kinsman 1977, 1981). Generally, Lokier's and Steuber's interesting description of the sediments in their pits seems to confirm those already published by previous workers. However, their key is rather misleading inasmuch as it suggests …