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<p>This study presents a geochemical analysis of clay deposits from Aïn Tellout and Koudiet el Mellah in the Tlemcen Mountains (Northwestern Algeria), aiming to elucidate their depositional environments, weathering intensity, sediment provenance, and paleoclimatic conditions. High Chemical Index of Alteration (CIA) and Plagioclase Index of Alteration (PIA) values at both sites indicate intense chemical weathering under warm and humid paleoclimates. Particularly high PIA values at Koudiet el Mellah suggest advanced plagioclase alteration, pointing to localized climatic conditions that intensified weathering. Elemental ratios such as SiO₂/Al₂O₃, Al₂O₃/TiO₂, and K₂O/Na₂O offer insights into sediment source and maturity. Moderate SiO₂/Al₂O₃ ratios at Aïn Tellout suggest a mixed provenance with limited transport, while higher ratios at Koudiet el Mellah imply more mature sediments likely shaped by greater weathering or longer transport. Differences in K₂O/Na₂O ratios further reflect varying feldspar alteration and detrital input between the two sites. Paleoredox conditions, evaluated using Ni/V and V/(V + Ni) ratios, reveal predominantly anoxic environments at Koudiet el Mellah, in contrast to more fluctuating redox conditions at Aïn Tellout, likely linked to seasonal water flow variations. Mineralogical evidence also points to salinity differences, with depositional settings ranging from freshwater to brackish/saline conditions. Prolonged surface exposure contributed to sustained chemical alteration, promoting sediment maturation. Together, these geochemical indicators provide a detailed reconstruction of the processes influencing clay deposition in this part of Northwestern Algeria.</p>

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Triassic clay geochemistry: understanding environmental dynamics in Tlemcen Mountains (Northwestern Algeria)

  • 期刊论文

  • 发表日期：

    2025年6月10日

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  • Kamar Eddine Bensefia,
  • Fatiha Hadji,
  • Abbas Marok

摘要

This study presents a geochemical analysis of clay deposits from Aïn Tellout and Koudiet el Mellah in the Tlemcen Mountains (Northwestern Algeria), aiming to elucidate their depositional environments, weathering intensity, sediment provenance, and paleoclimatic conditions. High Chemical Index of Alteration (CIA) and Plagioclase Index of Alteration (PIA) values at both sites indicate intense chemical weathering under warm and humid paleoclimates. Particularly high PIA values at Koudiet el Mellah suggest advanced plagioclase alteration, pointing to localized climatic conditions that intensified weathering. Elemental ratios such as SiO₂/Al₂O₃, Al₂O₃/TiO₂, and K₂O/Na₂O offer insights into sediment source and maturity. Moderate SiO₂/Al₂O₃ ratios at Aïn Tellout suggest a mixed provenance with limited transport, while higher ratios at Koudiet el Mellah imply more mature sediments likely shaped by greater weathering or longer transport. Differences in K₂O/Na₂O ratios further reflect varying feldspar alteration and detrital input between the two sites. Paleoredox conditions, evaluated using Ni/V and V/(V + Ni) ratios, reveal predominantly anoxic environments at Koudiet el Mellah, in contrast to more fluctuating redox conditions at Aïn Tellout, likely linked to seasonal water flow variations. Mineralogical evidence also points to salinity differences, with depositional settings ranging from freshwater to brackish/saline conditions. Prolonged surface exposure contributed to sustained chemical alteration, promoting sediment maturation. Together, these geochemical indicators provide a detailed reconstruction of the processes influencing clay deposition in this part of Northwestern Algeria.