Geochemical signatures of granitoids associated with skarns in central Anatolia

Many studies have shown systematic correlations between the composition of plutons worldwide and the metal contents of associated skarns. This is the first report of similar correlations between plutons and the skarns of the Akdagmadeni, Akcakisla, and Keskin districts in Central Anatolia. Herein, d ie genetic associations of skarn occurrences are investigated using the geo chemical compositions of the intrusives. In terms of major- and trace-element data, the granitoids associated with s karns show important differences. Three general groups of plutons, are dist inguished, and the distinction among them is based largely on major-element data. In general, the granitoids associated with Pb-Zn skarns in all three districts are classified as subalkaline/calc-alkaline, based on TAS and AF M diagrams, respectively. The Akdagmadeni and Keskin granitoids display S-t ype characteristics, and those of Akcakisla display I-type characteristics. As a whole, the granitoids in all districts display major-element geochemi cal characteristics (Harker diagrams) that typify plutons associated with w orldwide Zn, W, Mo, and Sn skarns. These data probably indicate that some o ther elements, like W in the Akdagmadeni district, and Mo + Sn in the Keski n district, could be associated with these skarns. Similarly, the granitoid s of Akdagmadeni and Akcakisla have trace-element geochemical signatures (Z r versus Ba and Zr versus Rb/Sr diagrams) that typify plutons associated wo rldwide with Zn, Cu, Mo, and W skarns. This also helps to underline the pos sible association of W and Mo skarns in the Akdagmadeni district, and Cu sk arns in the Akcakisla district. The average K2O/Na2O ratios of the plutons also serve to differentiate the granitoids associated with different types of skarns. The average K2O/Na2O ratio of the Keskin pluton it; 1.23, close to that of plutons associated wi th major Mo and Sn skarns. On the other hand, the average K2O/Na2O ratio of Akcakisla granite is very close to 1.0, close to that of plutons associate d with major Cu (and W?) as well as Pb and Zn. Therefore, these skarns shou ld be investigated in terms of the potential for those elements. This sugge sts new exploration possibilities for the Akcakisla, Akdagmadeni, and Keski n districts.