The Late Cretaceous Goft manganese deposit, southwest Sabzevar basin, Iran: geological, geochemical, and modelling evidence for a low-temperature exhalative origin into an oxic seafloor basin

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中文题名伊朗Sabzevar盆地西南部晚白垩世Goft锰矿床:有毒海底盆地低温呼气成因的地质、地球化学和建模证据
作者Shaghayegh Sadat Hashempour
作者单位Department of Geology, Faculty of Basic Sciences, Tarbiat Modares University, Tehran, Iran
刊名Arabian Journal of Geosciences
2023
16
01
摘要
The Cretaceous was an important period of manganese deposition in Iran, as evidenced by a series of medium-sized manganese deposits along the edge of the Neotethys ocean. This study characterizes representative example that occurs in Late Cretaceous volcanic rocks in the Goft deposit. This manganese deposit is typically volcanic hosted, with manganese-containing minerals, such as pyrolusite, psilomelane, cryptomelane, braunite, and manganite. The ore bodies hosted by red tuff are predominantly layered and usually have nodular structures. Replacement of Cretaceous foraminifers and radiolarians fossils by manganese minerals is also frequently observed in the Goft deposit. This deposit is a high-quality ore characterized by low P and Fe grades and an average Mn grade of approximately 14%. The average Mn/Fe, Co/Ni, Co/Zn, and V/(V + Ni) ratios in the Goft manganese deposit are 9.73, 0.24, 0.18, and 50, respectively. The overall REE contents are among 17.7 to 181 ppm, with an average of 87 ppm. The Ce/Ce* values of manganese ores vary from 0.26 to 0.99, with the mean of 0.53. The Eu/Eu* anomalies of the manganese oxide-hydroxide ores are close to 1 with a range of 0.70 to 1.22. Most manganese samples show negative Ce anomalies, indicating that the ore formation environment was predominantly oxide and cold conditions. The geochemical behavior of trace elements, including the REEs of the manganese oxide, provides clear evidence a low-temperature hydrothermal origin. The mineralogical and geochemical characteristics presented in this study strongly suggest a volcanogenic-exhalative genesis for Goft manganese deposit.

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