Using heavy minerals to test the stratigraphic framework of the Kufra Basin

The Palaeozoic sedimentary succession of the Kufra Basin contains substantial thicknesses of siliciclastic non-marine and often poorly age-dated sediments. In the absence of biostratigraphic data the correlation of formations relies solely on lithostratigraphic characteristics. In marine units macrofaunas are sparse and age-dating relies on palynomorphs and microfossil. Although biostratigraphic studies are possible on fossil material recovered from boreholes, extreme surface weathering ensures that such studies are impossible on material from outcrop. The lack of biostratigraphic data means that other tools have to be sought to test the correlation of units within and between basins

An integrated heavy mineral mineral chemical and zircon age dating study was undertaken on Neoproterozoic (Infracambrian) – Cretaceous sandstones from Jebel Dalma Jebel Asba and Jebel Arkenu on the northern and eastern margins of the Kufra Basin. The purpose of the study was to constrain the provenance of sediment and to assess the value of heavy minerals as a stratigraphic tool. Conventional heavy mineral analysis was carried out on 76 samples in combination with tourmaline garnet and rutile geochemical analyses and zircon age dating.

The study indicates that heavy mineral analysis is a useful technique for understanding the sediment provenance and the stratigraphic frame work of the Kufra Basin despite the intense weathering that surface samples have undergone. Using heavy mineral characteristics sandstones in the Kufra Basin succession can be divided into four units consisting of the following formations: 1. Arkenu Formation; 2. Hasawnah to Lower Tanezzuft formations; 3. Upper Tanezzuft and Akakus formations; 4. Tadrart and younger formations.