The Occurrence of Corundum-Rich Metabauxite in the Qaradash District, NW Iran

Abstract

The corundum-rich metabauxites were, very rare worldwide, reported in the Attic-Cycladic metamorphic complex in Greece and the southern and western margins of the Menderes Massif in southwestern Turkey. The Qaradash bauxite deposit is located in the Iran-Himalayan karst bauxite belt, 25km northwest of Shahindezh city, northwestern Iran (Figure 1a). The rock units in the Qaradash district mainly occur in an asymmetric fold and in the core of an anticline (Figure 1b). They, from the oldest to youngest, include the Permian carbonates of the Ruteh Formation, the Triassic sandstone and carbonate of the Elika Formation, and the Plio-Quaternary sandy conglomerate. Carbonates of the Ruteh Formation are dark grey in color that were intruded by the Oligocene monzonite and quartz monzonite intrusions. The marbles occur at the contact of these intrusions with carbonates of the Ruteh Formation. The bauxite horizons occur as 7-15-m-thick layers along the contact of carbonates of the Ruteh Formation (Permian) and sandstone and carbonate of the Elika Formation (Triassic) that were also affected by these intrusive masses and were partially converted to metabauxite. The analysis of the whole powered samples was carried out by powder X-ray diffraction (PXRD) using a Siemens D5000 at the Geological Survey of Iran, Tehran under the following conditions: Cu-K α radiation, 40kV, 30mA, scanning speed 8° per minute, and scan range 2°-60°. Whole-rock chemical analyses of the bauxites analyzed at the Activation Laboratories Ltd. Chemex, The analysis was performed on approximately 0.25g of the powdered samples, digested with lithium tetraborate and lithium metaborate