CONTRIBUTION TO THE ORIGIN OF THE URANIUM ANOMALY IN THE PLIOCENE AND PLEISTOCENE SEDIMENTS OF THE BASRAH REGION, SOUTH IRAQ
A spatially large uranium anomaly covering about 20000 Km2 has been identified in the Basrah region as a result of the regional geochemical soil survey of the Western and Southern deserts of Iraq carried out in the period (1978 – 1983). The anomaly is geogenic; related to a specific bedrock lithology and detected before the Gulf Wars of 1991 and 2003. The mineralogy of the Pliocene – Pleistocene sediments covering most of the anomalous area suggest that part of the U source may be attributed to the U-bearing primary unaltered U-bearing minerals in the fine clastic sediments, derived from the Arabian Shield. On the other hand, the hydrochemistry of the groundwater system and the origin of the uranium occurrences west of the Euphrates River, from Hit to Samawa, permit another possibility to explain the source of U-enrichment in the soils and sediments in the Basrah region, which is the epigenetic enrichment of U associated with evaporate minerals on the land surface originating from uraniferrous groundwater seepages. Uranium enrichment in the shallow aquifers of the area can be supplied from deep uraniferrous sources similar in this respect to numerous cases reported along the Anah – Abu Jir Fault system.