University of Isfahan Petrological Journal 2228-5210 17 1 2026 03 21 Petrographic, and Geochemical Investigation of listvenite in the Babalou area (Chaldran-West Azerbaijan) Petrographic, and Geochemical Investigation of listvenite in the Babalou area (Chaldran-West Azerbaijan) 85 112 30388 10.22108/ijp.2026.148256.1382 FA Shadi Sattari Ph.D. Student, Department of Earth Sciences, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran Mohammadreza Hosseinzadeh Professor, Department of Earth Sciences, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran Mohsen Moayyed Professor, Department of Earth Sciences, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran Nasrin Pourfathi M.Sc. Student, Department of Earth Sciences, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran Journal Article 2026 02 04 Introduction Listvenite is a metasomatic rock mainly composed of Mg-rich carbonates and quartz, formed by the interaction of CO₂-rich fluids with ultramafic rocks. Its main carbonate phase is typically magnesite, with variable iron content, and locally dolomite or calcite. Potassium-bearing fluids can alter chromian spinel to Cr-bearing muscovite (e.g., fuchsite). Listvenite represents a fully carbonated ultramafic rock, where divalent cations are hosted in carbonates, silica occurs as quartz/chalcedony/opal, and remnants of the protolith, such as chromian spinel, are preserved. It forms progressive alteration sequences from carbonated serpentinite to talc–carbonate rocks and finally to carbonate–quartz rocks—under high CO₂ activity and sustained fluid flux. Listvenites are relatively rare, occurring as lens-shaped or vein-like bodies within ophiolitic complexes and altered ultramafic rocks. They develop along tectonic contacts and plate-boundary faults with high CO₂ flux and have formed throughout Earth’s history from the Archean to the present Regional Geology Listvenites in the Babalou region occur as vein-like and lens-shaped bodies within the Khoy–Mako ophiolitic mélange, mainly along shear zones and faults, with mineralization trending parallel to the N50W orientation of the ophiolites. The mélange consists of Upper Cretaceous mafic and ultramafic fragments associated with pelagic limestones, and the listvenites are morphologically prominent due to their greater resistance to weathering and hard outcrops. In addition, metamorphosed intermediate to mafic rocks with dark grey to green colors are exposed within the colored mélange complexes of the area.. Analytical methods During fieldwork, samples were collected from metamorphic rocks, metamorphosed mafic–intermediate rocks of the ophiolite–mélange, listvenite alteration zones, and some sedimentary units, and the general geology of the area was investigated. A total of 30 thin sections and 10 polished sections were prepared for petrographic and mineragraphic studies. Based on these results, 10 listvenite samples and 6 metamorphosed mafic–intermediate samples were selected and analyzed by ICP–MS at Actlabs, Canada. Petrography, Mineralogy and Whole Rock Chemistry Metamonzodiorite–meta-Gabbro to Metadiorite– meta-Gabbro (DG) The rocks display a granoblastic texture and are dominated by plagioclase, K-feldspar, amphibole, clinopyroxene, and epidote, with sphene as the main accessory. Plagioclase commonly shows deformation (bending/kinking), while clinozoisite occurs as an alteration product of amphibole and plagioclase. Meta Quartz Monzodiorite (QD) The rocks are composed of plagioclase, K-feldspar, quartz, muscovite, and epidote (allanite/pistacite), with minor biotite and rutile. They have undergone significant silicic–carbonate alteration, resulting in secondary chlorite, epidote, muscovite, and malachite. Notably, amorphous brown allanite is observed partially altering to pistacite. Silicic–Carbonate Listvenite These rocks are primarily composed of quartz and carbonate. Quartz shows deformation and some recrystallization, while carbonate occurs in the matrix, crystals, and veins. Two generations of muscovite are present, and fuchsite likely formed during the late stage of listvenitization. Silicic Listvenite These rocks consist mainly of quartz and calcite, with minor muscovite and opaque minerals. Quartz occurs as crystalline quartz and chalcedony, commonly showing fracturing, brecciation, and cavity filling. Siliceous veins display radial to feather-like textures and may form geode-like structures. Carbonates are mostly calcite, with minor dolomite, occurring in grains, veins, and fractures. Discussion Listvenite formation in the Babalu region resulted from CO₂-rich, K-bearing hydrothermal fluids moving through faults and shear zones after ophiolite emplacement and tectonic activity. The alteration was controlled by temperature, pH, oxygen fugacity, and sulfur fugacity. This process occurred in three main stages: carbonatization, with formation of calcite, dolomite, chlorite, epidote, and tremolite; silicification, with addition of silica and formation of quartz; and mica formation in the late stage. Repeated veining shows multiple pulses of alteration, and pyrite and chalcopyrite formed during cooler or chemically favorable fluid conditions. The SiO₂–LOI and SiO₂–(CaO+MgO)–Fe₂O₃ ternary diagrams both classify the studied rocks as siliceous listvenites. In SiO₂–LOI space, they plot in the high silica, low LOI field. In the SiO₂–Fe₂O₃–(CaO+MgO) diagram, they lie near the SiO₂ apex along the (CaO+MgO)–SiO₂ edge, reflecting low Fe content and the scarcity of Fe-rich carbonates such as ankerite and siderite. Chondrite-normalized REE patterns distinguish the two listvenite types. Siliceous listvenites are very REE-poor, nearly flat, and show a strong positive Eu anomaly, likely from calcic plagioclase alteration. Siliceous–carbonate listvenites have slightly higher REE contents but no Eu anomaly, probably due to calcite. Their (La/Yb)n ratios indicate gentle to moderate fractionation. Tectonic data place the meta quartz monzodiorite in the VAG field and the meta monzodiorite–meta diorite–meta gabbro in the continental arc field, so neither is a likely ophiolitic source for the listvenites. The most probable source is another, unidentified ophiolitic rock in the area. Acknowledgements The authors sincerely thank all individuals who contributed in any way to this research and the preparation of this article, especially colleagues and reviewers whose constructive comments and suggestions helped improve the quality of the manuscript. Introduction Listvenite is a metasomatic rock mainly composed of Mg-rich carbonates and quartz, formed by the interaction of CO₂-rich fluids with ultramafic rocks. Its main carbonate phase is typically magnesite, with variable iron content, and locally dolomite or calcite. Potassium-bearing fluids can alter chromian spinel to Cr-bearing muscovite (e.g., fuchsite). Listvenite represents a fully carbonated ultramafic rock, where divalent cations are hosted in carbonates, silica occurs as quartz/chalcedony/opal, and remnants of the protolith, such as chromian spinel, are preserved. It forms progressive alteration sequences from carbonated serpentinite to talc–carbonate rocks and finally to carbonate–quartz rocks—under high CO₂ activity and sustained fluid flux. Listvenites are relatively rare, occurring as lens-shaped or vein-like bodies within ophiolitic complexes and altered ultramafic rocks. They develop along tectonic contacts and plate-boundary faults with high CO₂ flux and have formed throughout Earth’s history from the Archean to the present Regional Geology Listvenites in the Babalou region occur as vein-like and lens-shaped bodies within the Khoy–Mako ophiolitic mélange, mainly along shear zones and faults, with mineralization trending parallel to the N50W orientation of the ophiolites. The mélange consists of Upper Cretaceous mafic and ultramafic fragments associated with pelagic limestones, and the listvenites are morphologically prominent due to their greater resistance to weathering and hard outcrops. In addition, metamorphosed intermediate to mafic rocks with dark grey to green colors are exposed within the colored mélange complexes of the area.. Analytical methods During fieldwork, samples were collected from metamorphic rocks, metamorphosed mafic–intermediate rocks of the ophiolite–mélange, listvenite alteration zones, and some sedimentary units, and the general geology of the area was investigated. A total of 30 thin sections and 10 polished sections were prepared for petrographic and mineragraphic studies. Based on these results, 10 listvenite samples and 6 metamorphosed mafic–intermediate samples were selected and analyzed by ICP–MS at Actlabs, Canada. Petrography, Mineralogy and Whole Rock Chemistry Metamonzodiorite–meta-Gabbro to Metadiorite– meta-Gabbro (DG) The rocks display a granoblastic texture and are dominated by plagioclase, K-feldspar, amphibole, clinopyroxene, and epidote, with sphene as the main accessory. Plagioclase commonly shows deformation (bending/kinking), while clinozoisite occurs as an alteration product of amphibole and plagioclase. Meta Quartz Monzodiorite (QD) The rocks are composed of plagioclase, K-feldspar, quartz, muscovite, and epidote (allanite/pistacite), with minor biotite and rutile. They have undergone significant silicic–carbonate alteration, resulting in secondary chlorite, epidote, muscovite, and malachite. Notably, amorphous brown allanite is observed partially altering to pistacite. Silicic–Carbonate Listvenite These rocks are primarily composed of quartz and carbonate. Quartz shows deformation and some recrystallization, while carbonate occurs in the matrix, crystals, and veins. Two generations of muscovite are present, and fuchsite likely formed during the late stage of listvenitization. Silicic Listvenite These rocks consist mainly of quartz and calcite, with minor muscovite and opaque minerals. Quartz occurs as crystalline quartz and chalcedony, commonly showing fracturing, brecciation, and cavity filling. Siliceous veins display radial to feather-like textures and may form geode-like structures. Carbonates are mostly calcite, with minor dolomite, occurring in grains, veins, and fractures. Discussion Listvenite formation in the Babalu region resulted from CO₂-rich, K-bearing hydrothermal fluids moving through faults and shear zones after ophiolite emplacement and tectonic activity. The alteration was controlled by temperature, pH, oxygen fugacity, and sulfur fugacity. This process occurred in three main stages: carbonatization, with formation of calcite, dolomite, chlorite, epidote, and tremolite; silicification, with addition of silica and formation of quartz; and mica formation in the late stage. Repeated veining shows multiple pulses of alteration, and pyrite and chalcopyrite formed during cooler or chemically favorable fluid conditions. The SiO₂–LOI and SiO₂–(CaO+MgO)–Fe₂O₃ ternary diagrams both classify the studied rocks as siliceous listvenites. In SiO₂–LOI space, they plot in the high silica, low LOI field. In the SiO₂–Fe₂O₃–(CaO+MgO) diagram, they lie near the SiO₂ apex along the (CaO+MgO)–SiO₂ edge, reflecting low Fe content and the scarcity of Fe-rich carbonates such as ankerite and siderite. Chondrite-normalized REE patterns distinguish the two listvenite types. Siliceous listvenites are very REE-poor, nearly flat, and show a strong positive Eu anomaly, likely from calcic plagioclase alteration. Siliceous–carbonate listvenites have slightly higher REE contents but no Eu anomaly, probably due to calcite. Their (La/Yb)n ratios indicate gentle to moderate fractionation. Tectonic data place the meta quartz monzodiorite in the VAG field and the meta monzodiorite–meta diorite–meta gabbro in the continental arc field, so neither is a likely ophiolitic source for the listvenites. The most probable source is another, unidentified ophiolitic rock in the area. Acknowledgements The authors sincerely thank all individuals who contributed in any way to this research and the preparation of this article, especially colleagues and reviewers whose constructive comments and suggestions helped improve the quality of the manuscript.

https://ijp.ui.ac.ir/article_30388_f36db9a576da6603e1f23469aabb8820.pdf