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摘要
This paper presents the results of an integrated heavy mineral and mineral chemical study of Precambrian-Mesozoic clastic sediments from the eastern Murzuq Basin. The purpose of this 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 64 samples, tourmaline geochemical analysis on 25 samples, garnet geochemical analysis on four samples, rutile geochemical analysis on 21 samples, and clinopyroxene geochemical analysis on two 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 appear to be three key events when the provenance signature changed within the Palaeozoic-Mesozoic sedimentary succession at the eastern Murzuq Basin: (i) at the base of the Tanezzuft Formation (early Silurian), (ii) at the base of the Tadrart Formation (Early Devonian), and (iii) at the base of the Mrar Formation (Carboniferous), subdividing the succession into four intervals (Hasawnah-Mamuniyat, Tanezzuft-Akakus, Tadrart-Awaynat Wanin, and Mrar-Nubian). There is probably also an event between the Precambrian and the Hasawnah Formation (Cambrian), but there are currently insufficient data to prove this unequivocally. 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.
- 出版日期2011-11
