Assessment of Biogenic and Abiogenic Mineralization Processes in Sediment-Hosted Metal Deposits of the Upper Red Formation, Mahneshan Region, NW Iran
Authors
1
School of Geology, College of Science, University of Tehran,Tehran, Iran
2
Department of Geology, Faculty of Science, University of Zanjan, Zanjan, Iran
10.30470/zpaleo.2024.732532
Abstract
The Upper Red Formation in the Mahneshan region (Zanjan province, northwestern Iran) consists of Miocene detrital sequences that are of interest in terms of sedimentology, paleontology, and economic geology. Most of the metal mineralization in the detrital layers of this Formation consists of copper-bearing minerals, which are often represented by three distinct color zones (red-oxidizing, white-bleaching, and green-reducing). The association of ore-bearing layers with plant remains and vertebrate or invertebrate trace fossils, suggests the role of biogenic processes in this type of mineralization. In this study, based on field observations, sedimentary petrology, and paleontological evidences, the possible relationship between organic matter and copper mineralization was investigated. The results show that under local reduction conditions, organic carbon from plant remains played a very important role in the absorption and concentration of Cu minerals, which are observed in the green-reducing sedimentary zones of anoxic conditions. Also, the discovery of the invertebrate traces with the concentration of metal ores in the burrow sediments fills suggests the hypothesis that biological activities played a role in metal mineralization. Despite such evidence, it shows the importance of paying attention to biological signs in mineralization processes and emphasizes the need for future research with a geochemical and isotopic approach.
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