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<p>Ferruginous cherts and associated siliciclastic rocks of the Neoproterozoic Buem Structural Unit (Eastern Ghana) provide a unique archive for reconstructing fluid sources, hydrothermal processes, and basin evolution along the margin of the West African Craton. This study presents new whole-rock major and trace element geochemical data from cherts, shales, and sandstones to constrain the origin of the ferruginous facies and evaluate the influence of hydrothermal activity and depositional redox conditions. The ferruginous cherts display enrichments in Fe<sub>2</sub>O<sub>3</sub>, Ba, Sr, and transition metals (Cu, Ni, Zn), together with elevated ΣREE and moderately fractionated chondrite-normalized patterns. Positive Eu anomalies (Eu/Eu<sup>*</sup> = 1.05–1.30), variable Ce anomalies, and high Y/Ho ratios (20–28) indicate mixing between seawater-derived silica and high-temperature hydrothermal fluids, likely sourced from mafic volcanic substrates. PAAS-normalized patterns of both cherts and siliciclastics suggest limited terrigenous dilution in the ferruginous cherts but significant detrital inputs in the shales and sandstones, dominated by felsic to intermediate crustal material. Trace element ratios including Th/U, V/Cr, Ni/Co, and U concentrations collectively indicate predominantly oxic to sub-oxic depositional conditions with localized reducing microenvironments associated with Fe–Mn-rich fluids. Provenance-sensitive indicators (e.g., La/Sc, Th/Sc, Zr/Hf) in the shales and sandstones, although deposited on a passive margin, point to a continental margin affinity consistent with the erosion of the Birimian Supergroup and Pan-African granitoid sources. These geochemical signatures reveal that the Buem basin evolved under the combined influence of hydrothermal venting, silica-iron precipitation, and sustained detrital influx from adjacent continental sources. The ferruginous cherts represent the main hydrothermal imprint in the sequence, whereas the siliciclastics record broader basin-scale provenance and redox signatures. These results refine the understanding of Neoproterozoic basin dynamics in southeastern Ghana and highlight the role of hydrothermal activity in shaping chemical sedimentation within the Pan-African orogenic framework.</p>

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Whole-rock geochemical constraints on origin of ferruginous chert and associated rocks from the Neoproterozoic Buem Structural Unit, Eastern Ghana: Implications for hydrothermal activity and tectonic setting

  • 期刊论文

  • 发表日期：

    2026年4月20日

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  • Rauda Adam Addae,
  • Huayong Chen,
  • Bing Xiao

摘要

Ferruginous cherts and associated siliciclastic rocks of the Neoproterozoic Buem Structural Unit (Eastern Ghana) provide a unique archive for reconstructing fluid sources, hydrothermal processes, and basin evolution along the margin of the West African Craton. This study presents new whole-rock major and trace element geochemical data from cherts, shales, and sandstones to constrain the origin of the ferruginous facies and evaluate the influence of hydrothermal activity and depositional redox conditions. The ferruginous cherts display enrichments in Fe2O3, Ba, Sr, and transition metals (Cu, Ni, Zn), together with elevated ΣREE and moderately fractionated chondrite-normalized patterns. Positive Eu anomalies (Eu/Eu* = 1.05–1.30), variable Ce anomalies, and high Y/Ho ratios (20–28) indicate mixing between seawater-derived silica and high-temperature hydrothermal fluids, likely sourced from mafic volcanic substrates. PAAS-normalized patterns of both cherts and siliciclastics suggest limited terrigenous dilution in the ferruginous cherts but significant detrital inputs in the shales and sandstones, dominated by felsic to intermediate crustal material. Trace element ratios including Th/U, V/Cr, Ni/Co, and U concentrations collectively indicate predominantly oxic to sub-oxic depositional conditions with localized reducing microenvironments associated with Fe–Mn-rich fluids. Provenance-sensitive indicators (e.g., La/Sc, Th/Sc, Zr/Hf) in the shales and sandstones, although deposited on a passive margin, point to a continental margin affinity consistent with the erosion of the Birimian Supergroup and Pan-African granitoid sources. These geochemical signatures reveal that the Buem basin evolved under the combined influence of hydrothermal venting, silica-iron precipitation, and sustained detrital influx from adjacent continental sources. The ferruginous cherts represent the main hydrothermal imprint in the sequence, whereas the siliciclastics record broader basin-scale provenance and redox signatures. These results refine the understanding of Neoproterozoic basin dynamics in southeastern Ghana and highlight the role of hydrothermal activity in shaping chemical sedimentation within the Pan-African orogenic framework.