Climate change and the formation of nickel laterite deposits

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One of the major controls on nickel laterite deposit formation is climate. A comparison of climatic data for regions where ultramafic rocks are exposed shows that areas currently conducive to nickel laterite formation receive >1000 mm/yr precipitation, have cold month mean (CMM) temperatures between 15 and 27 °C, and warm month mean (WMM) temperatures between 22 and 31 °C. Using a compilation of paleoclimatic data and the defined climatic window of nickel laterite deposit formation allows an assessment of the timing and duration of paleo–nickel laterite formation in ancient terrains. To illustrate the potential of this technique, we show that the formation of the Caldag nickel laterite deposit of western Turkey most likely initiated when the ultramafic protolith of Cretaceous age was exposed in the Early Eocene, and that the majority of the deposit formed during the Eocene. In contrast, the formation of the Bitincke deposit, south Albania, was mostly complete by the Early Eocene, after which CMM temperatures dropped below the optimum for laterite formation.