Geochemistry and petrography of beach sands along the western coast of Ghana: implications for provenance and tectonic settings
Küçük Resim Yok
Tarih
2020
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Tubitak Scientific & Technological Research Council Turkey
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
The paleoweathering, provenance, and tectonic setting of sediments of the western coast of Ghana were unraveled using the geochemistry of 29 beach sands, which are characterized by coarse-, medium-, and fine-grained sizes. The coarse-grained beach sands contain higher SiO2 content (2.9-96 wt.%) than the medium-grained (4.9-94 wt.%) and fine-grained (16.1-90.7 wt.%) sands, implying that the increase in grain size is related to the increase in SiO2 content. Al2O3 and CaO concentrations are higher in the fine- and medium-grained sands than the coarse-grained sands. The beach sands are compositionally immature based on the index of compositional variable values (1.17-141) and Th/Sc versus Zr/Sc diagram although they have high SiO2/Al2O3 values. The high SiO2/Al2O3 is not indicative of the weathering conditions of the coastal sediments in the area. The sands are chemically unaltered clastic materials of first cycle regime that still have their labile minerals retained in them very close to the sediment source based on the chemical index of alteration values, plagioclase index of alteration values, and A-CN-K and A-CNK-FM ternary diagrams. The total rare earth elements (Sigma REE) content increases with decreasing grain size. However, there are some discrepancies where some coarsegrained samples have high Sigma REE content. This suggests that apart from the grain size, the provenance of the sediments has direct control over their geochemical composition. The correlation of the rare earth elements patterns of the beach sands with those of adjacent source rocks points to felsic sources for their derivation. The felsic (granodioritic composition) igneous suites of the Paleoproterozoic Birimian highland rocks adjacent to the beach sediments in the western coast are possibly the source rocks of the beach sands. Rifting in the continents is the tectonic regime probably during the Paleoproterozoic times responsible for deposition of the beach sands in the western coast of Ghana.
Açıklama
Anahtar Kelimeler
Beach sands, geochemistry, provenance, tectonic setting, western coast, Ghana
Kaynak
Turkish Journal of Earth Sciences
WoS Q Değeri
Q4
Scopus Q Değeri
Q2
Cilt
29
Sayı
2
