Geochemical Characteristics of Sedimentary Manganese Deposit of Binkılıç, Trache Basin, Turkey

Abstract

The Binkilic manganese deposit, occurring in the Congeria and Fish Series of the Oligocene in Thrace Basin, is associated with relatively rapid marine transgressions and regressions across older basement rock and is called as shallow-marine basin-margin deposit. The geochemical characteristics of the deposit were examined by means of major oxide, trace and rare elements (REE) contents and the origin of mineralization was discussed. The deposit contains lower Mn / Fe ratios than those of hydrothermal and sedimentary exhalative deposits. The concentrations of Ba, Co, Sr, Cu, Zn and Ni are closely related to the increase of manganese content and indicate the element’s nature in various manganese minerals. According to trace element spider diagram normalized to shale composite NA, the ore is clearly enriched in Sr, Ni while distinctly depleted in Rb. The chemical analysis results indicated that total REE contents of the samples are relatively low and the ratio of ΣLREE/ΣHREE shows a primary enrichment for LREE that has occurred during the Mn oxidation process. The increase in total LREE is mainly associated with the amount of terrigenous material that was transported in the depositional environment. The chondrite-normalized REE patterns are remarkably similar, yielding HREE-depleted curves with a small negative Ce and middle positive Eu anomalies and reflect their same origin of ore source. The Ce values and Ce/Ce* ratios show that the Binkilic deposit is mainly associated with the marine basin and the ore is formed in both anoxic and oxic conditions. The major oxide, trace element and REE assessments indicated that the Binkilic Mn deposit occurred as a diagenetic type of Mn deposit with terrigenous material addition, but some manganese oxides are related to the upwelling of reducing waters containing abundant organic matter and dissolved Mn to the shallow-marine areas.