Development and evolution of subaerial halite crust morphologies in a coastal sabkha setting

摘要

The halite crusts of the coastal Abu Dhabi Sabkha were monitored and described in order to assess their temporal evolution and their potential for preservation and recognition in ancient sabkha sequences. The position of polygon ridges is controlled by subtle differences in the sabkha surface topographytypically in the form of low lying mud ridges and exposed halite. Where this topography remains undisturbed, then successive generations of halite polygons were observed to form with borders in the same location. As each generation of halite crust effectively 'rebuilds' the controlling mud ridge, then this process can be seen as self perpetuating until disturbed by a major erosional event. In marginal marine settings, such as the Abu Dhabi Sabkha, the preservation potential of the halite crust is negligible. While associated sedimentary structures have been employed to infer the presence of an earlier halite crust in other geographic settings, these all require a net influx of sediment to the depositional system. The absence of such a sediment supply in the coastal-fringing Abu Dhabi Sabkha is inferred to be a major constraint to the preservation and recognition of halite crusts and their associated features into the sedimentary record.