TY - JOUR
T1 - Provenance and source area weathering of sandstones from the Tarkwaian Group at the northeastern extent of the Paleoproterozoic Ashanti Belt, Ghana
T2 - Constraints from petrography and geochemistry
AU - Sedziafa, Victor
AU - Song, Ying
AU - Sunkari, Emmanuel Daanoba
AU - Kwayisi, Daniel
AU - Anani, Chris Y.
AU - Asiedu, Daniel K.
N1 - Publisher Copyright:
© 2025 Elsevier Ltd
PY - 2025/4
Y1 - 2025/4
N2 - An integrated geochemical and petrographic study was conducted on the Paleoproterozoic sandstones of the Tarkwaian Group exposed at the northeastern extent of the Ashanti Belt, Ghana. Recognizing the economic importance of the Tarkwaian Group, particularly owing to its extensive gold deposits, the primary objective was to investigate the provenance, tectonic setting, and crustal evolution of the Tarkwaian Group. The dominant quartz (polycrystalline and monocrystalline), together with minor muscovite, feldspar, hematite, and lithic fragments, characterize the sandstones and thus, the sandstones are classified as sublitharenite, and lithicsubarkose. Based on mineralogical composition and major element content, the sandstones can be classified as litharenite, sublitharenite, and minor greywacke. The high values of SiO2/Al2O3 (average: 12.74), relatively moderate values of K2O/NaO2 (average: 1.42), and high quartz content (average: 88%) suggest that the sediments are compositionally sub-mature to mature. The sandstones likely underwent low to moderate levels of sedimentary sorting and recycling owing to angular to sub-rounded grains and moderate Zr/Sc and Th/Sc values. The high Chemical Index of Alteration (CIA) signature (average: 76.79 wt%), Plagioclase Index of Alteration (PIA) values (average: 90.13 wt%), and Index of Compositional Variability (ICV) (average: 0.61 wt%) suggest moderate to intense chemical weathering within the region of origin. Overall, the mineralogical and geochemical features of the sandstones, such as a high proportion of quartz and feldspar, and elevated concentrations of elements such as Zr, Sc and Th, and moderate to high ratios of Al2O3/TiO2 and La/Sc indicate that they were likely sourced from felsic to intermediate igneous rocks and deposited in an active continental margin such as magmatic arc setting.
AB - An integrated geochemical and petrographic study was conducted on the Paleoproterozoic sandstones of the Tarkwaian Group exposed at the northeastern extent of the Ashanti Belt, Ghana. Recognizing the economic importance of the Tarkwaian Group, particularly owing to its extensive gold deposits, the primary objective was to investigate the provenance, tectonic setting, and crustal evolution of the Tarkwaian Group. The dominant quartz (polycrystalline and monocrystalline), together with minor muscovite, feldspar, hematite, and lithic fragments, characterize the sandstones and thus, the sandstones are classified as sublitharenite, and lithicsubarkose. Based on mineralogical composition and major element content, the sandstones can be classified as litharenite, sublitharenite, and minor greywacke. The high values of SiO2/Al2O3 (average: 12.74), relatively moderate values of K2O/NaO2 (average: 1.42), and high quartz content (average: 88%) suggest that the sediments are compositionally sub-mature to mature. The sandstones likely underwent low to moderate levels of sedimentary sorting and recycling owing to angular to sub-rounded grains and moderate Zr/Sc and Th/Sc values. The high Chemical Index of Alteration (CIA) signature (average: 76.79 wt%), Plagioclase Index of Alteration (PIA) values (average: 90.13 wt%), and Index of Compositional Variability (ICV) (average: 0.61 wt%) suggest moderate to intense chemical weathering within the region of origin. Overall, the mineralogical and geochemical features of the sandstones, such as a high proportion of quartz and feldspar, and elevated concentrations of elements such as Zr, Sc and Th, and moderate to high ratios of Al2O3/TiO2 and La/Sc indicate that they were likely sourced from felsic to intermediate igneous rocks and deposited in an active continental margin such as magmatic arc setting.
KW - Ashanti belt
KW - Provenance
KW - Sandstone
KW - Tarkwaian group
KW - Tectonic setting
UR - http://www.scopus.com/inward/record.url?scp=85215387886&partnerID=8YFLogxK
U2 - 10.1016/j.jafrearsci.2025.105536
DO - 10.1016/j.jafrearsci.2025.105536
M3 - Article
AN - SCOPUS:85215387886
SN - 1464-343X
VL - 224
JO - Journal of African Earth Sciences
JF - Journal of African Earth Sciences
M1 - 105536
ER -