|
Aeolian Sediments: Dune Dynamics and Deposits |
Department of Geology, Kuwait University, Box 5969, Kuwait 13060
Small evaporitic pans within a sand-sheet/gravel-plain terrain characterize the coastal margins of southern Kuwait. Sedimentological studies indicate that the pans commenced as ephemeral lakes during a Pleistocene pluvial phase, and later evolved into sabkhas during the Holocene with the changing climatic and hydrological regimes. The lacustrine episode is represented by laminated calcite micrite in the lower parts of the section, grading upward into a diagenetic gypsum facies of the sabkhas, with diagnostic evaporite textures. Dunes are represented only by nebkhas, which occur within the sabkha pans. Their initial build-up is controlled by a halophyte which colonizes the sabkha surface, trapping any moving sand. The nebkhas pass through phases of growth, stabilization and decay that are controlled by fluctuations in the water table. A rise of the water table can waterlog the roots and kill the plants—in which case the trapped sand starts drifting. A continued fall in the water table can lead to deflation of the entire complex. The nebkhas have a poor preservation potential. In this area the aeolian system is highly starved of sand in relation to the available wind energy. Stable isotope data indicate that the groundwaters are derived from old formation waters, with only minor meteoric recharge.
