Geochemistry provenance and depositional tectonic setting of the Adigrat Sandstone northern Ethiopia

✍ Scribed by Worash Getaneh

• Book ID: 104354128
• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 522 KB
• Volume: 35
• Category: Article
• ISSN: 1464-343X
• DOI: 10.1016/s0899-5362(02)00126-4

✦ Synopsis

The Adigrat Sandstone in northern Ethiopia was sampled for chemical and mineralogical analysis. The samples were analysed for major elements, rare earth and other trace elements by XRF and ICP-MS. The mineralogy was studied using petrographic microscopes and XRD. The results were used to infer the provenance and geotectonic setting of the depositional basin.

Quartz (average of 91%), with subordinate amount of clays and K-feldspar, dominates the mineralogy of the Adigrat Sandstone indicating that the sandstone is highly recycled and matured. The apparent source material was a quartzose sedimentary rock, which is represented in the study area by the Palaeozoic sediments of the region. However, the low values of Eu/Eu à , Ta/Ta à , Cr/Th and high values of LREE/HREE, La/Sc, Th/Sc, Th/Co, and the REE pattern, demonstrate that its ultimate sources were silicic to intermediate (granites, granodiorites and granitic gneiss) rocks of the nearby basement. The dominance of quartz in the mineralogy together with enrichment in the immobile elements like La, Zr, Hf and others, suggest that the tectonic setting of the depositional basin formed part of a passive margin.