AN OVERVIEW OF THE TERTIARY GEOLOGY AND HYDROGEOLOGY OF THE NORTHERN PART OF THE ARABIAN GULF REGION WITH SPECIAL REFERENCE TO KUWAIT

Tertiary sediments constitute the main source of usable groundwater in Kuwait. Tectonics, depositional environment, lithology and the hydrog eology of these sediments have been reviewed on a regional scale, with special reference to Kuwait. The review showed that Kuwait was situat ed at the boundary of the stable shelf towards southwest and the unsta ble shelf towards northeast throughout the Tertiary period. The Tertia ry sedimentation started in this area with a marine transgression in t he Palaeocene. Shallow marine to sabkha conditions prevailed in the ar ea until the end of the Eocene; a carbonate-evaporite sequence (Umm Er -Radhuma, Rus and Dammam Formation) was deposited during this period. The sea regressed at the End of Eocene, and a widespread unconformity, causing the absence of Oligocene deposits over most of the area, mark ed the event. The karstification of the Dammam Limestone Formation, th at provides localized easier pathways for ground water, took place dur ing this period. The deposition of the elastic sediments of the Kuwait Group and its equivalents on the stable shelf, under mostly continent al conditions, started in the early Miocene. The Tertiary aquifers of the area are recharged by occasional rainstorms in the outcrops of Sau di Arabia and Iraq. The water flows towards the north and east in the direction of the regional dip and discharges along the present-day coa st of the Gulf. The water quality deteriorates in the same direction, being more mineralized as it flows through the aquifers. The aquifers are presently bring exploited at a comparatively high rate. Since the aquifers extend beyond the political boundaries, cooperation among the countries of the region is recommended to ensure the optimum utilizat ion of the scarce water resources of this desert environment.