PROVENANCE STUDIES IN THE MURZUQ BASIN OF SOUTHERN LIBYA

The geodynamic history of the Saharan Metacraton as well as the age and provenance of its sedimentary cover sequence are still poorly constrained. Here we present the results of an integrated heavy mineral and mineral chemical study of Precambrian–Mesozoic clastic sediments from the eastern Murzuq Basin of southern Libya. In addition, first detrital zircon U–Pb ages (obtained by LA-SF-ICP-MS and SHRIMP-RG) from Palaeozoic and Mesozoic quartz-rich sandstones are discussed. The purpose of this study was to constrain the provenance of sediment and to further assess the value of heavy minerals as a stratigraphic tool. Conventional heavy mineral analysis was carried out on 64 samples, tourmaline geochemical analysis on 25 samples, garnet geochemical analysis on 4 samples, rutile geochemical analysis on 21 samples, and clinopyroxene geochemical analysis on 2 samples. The study indicates that heavy mineral analysis is a valuable tool for understanding the provenance of Palaeozoic and Mesozoic clastic sediments in Libya, despite the intense weathering that surface samples have undergone. Based on heavy mineral ratios and mineral chemical data, there appears to be three key events when the provenance signature changed within the Palaeozoic–Mesozoic sedimentary succession at the eastern Murzuq Basin: at the base of the Tanezzuft Formation (early Silurian), at the base of the Tadrart Formation (Devonian), and at the base of the Mrar Formation (Carboniferous), subdividing the succession into four intervals (Hasawnah–Mamuniyat, Tanezzuft–Akakus, Tadrart–Awaynat Wanin, and Mrar–Nubian). Comparing data of the present study with results from the previous work in the Kufra Basin, it is evident that heavy mineral data provide useful evidence for differences in provenance both regionally and stratigraphically in basins of the central Sahara.