Banded manganese-chert mineralization, characterized by distinct banding, is identified for the first time in chert-hosted manganese deposits of the deep marine Qulqula Radiolarian Formation, Halabja Province, Kurdistan Region, Iraq. These mineralization styles display alternating millimeter- to centimeter-scale light and dark bands, composed of cryptocrystalline silica and manganese phases, respectively resembling zebra-like patterns. Petrographic and scanning electron microanalysis reveal that zoned todorokite (∼Ca₀.₁₂K₀.₀₁)(Mn₅.₇Fe²⁺₀.₂Mg₀.₁)O₁₂·4H₂O) formed via late diagenetic recrystallization of bannisterite (∼ (K₀.₂Ca₀.₅)(Mn₆ Fe₂ Mg₀.₇)(Si₁₁Al₁) O₃₀(OH)₇·4H₂O), demonstrating complex mineralogical transformations. The core-to-rim Fe and Mn variations in euhedral todorokite indicate significant geochemical shifts during diagenesis, influenced by fluctuations in Fe ions availability. This process reflects dynamic environmental conditions affecting manganese mineral formation over time during various evolution stages of Neotethys ocean. The host chert's low aluminum content and high Fe/Mn ratio suggest low temperature serpentinization derived hydrothermal fluids played a crucial role in mineralization. Geochemical and textural evidence further supports hydrothermal activity as the primary driver of both deposition and diagenesis, leading to the development of banded manganese mineralization in the Qulqula Radiolarian Formation. Post-depositional spongy chert texture further supports structural transformations among manganese phases resulting from diagenetic processes. These findings enhance our understanding of the mineralogical and geochemical processes that govern hydrothermal banded manganese deposits in the deep marine Neotethyan radiolarite facies.

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