Neotocite textures as a clue to the exploration of Red Bed type sediment-hosted stratabound copper (SSC) deposits – evidence from Ravar–Tabas–Eshghabad copper belt, Central Iran

Abstract

ABSTRACT Red Bed type sediment-hosted stratabound copper (SSC) deposits consist of replaced, disseminated to veinlets copper sulphides, hosted by thick, haematite-stained sequences of sandstone, conglomerate, and siltstone. More than 120 sediment-hosted stratabound copper (SSC) deposits and occurrences have been reported in Iran. Ravar–Tabas–Eshghabad is the major Red Bed type SSC belt in Iran, with a cumulative tonnage of more than 400 Mt ore at ~1–2% Cu. These deposits are hosted in Garedu Red Bed Formation (including reddish conglomerates and micro-conglomerates, red siltstones and sandstones), and copper sulphides (chalcocite, with minor chalcopyrite and bornite) are concentrated in local reducing conditions that are achieved around plant fossil accumulations, within grey paleochannels in the upper part of the Garedu Red Bed Formation. These deposits are usually explored using geochemical, geophysical, and remote sensing methods. However, the host layers usually extend laterally up to tens of kilometres, and the critical point is to find the paleochannels in the host horizons where organic matter and plant fossils accumulate, especially in underground mining and boreholes. The lateral extension of ore-bearing lenses is usually 50–150 m, so it is not easy to find them within the reduced horizons. Recognizing neotocite textures (including diffusion, radial DLA (diffusion-limited aggregation), cat footprint, and spotty), and distribution in the host rocks of the Red Bed type SSC deposits can be used as a clue to find the ore lenses, organic matter, and plant fossil accumulations.