GEOCHEMICAL CHARACTERISTICS OF GRANITOIDS ALONG THE WESTERN MARGIN OFTHE CENTRAL ANATOLIAN CRYSTALLINE COMPLEX AND THEIR TECTONIC IMPLICATIONS

The closely related assemblage of igneous and metamorphic rocks that l ie within a triangular area approximately bounded by the Tuzgolu Fault , the Ecemis Fault and the Izmir-Ankara-Erzincan Suture and between th e lines connecting Ankara, Sivas and Nigde is called the Central Anato lian Crystalline Complex (CACC). The granitoids cropping out within th e CACC can be divided areally into three groups: (1) a large number of individual small plutons which form an arcuate set and curve from NE- SW to NW-SE and extend from Sulakyurt to Nigde along the western margi n; (2) a relatively narrow and smaller set of disconnected plutons ext ending from Sivas to Camardi along the eastern margin; and (3) a very large batholith along the northern margin exposed around Yozgat. This study deals only with the first group of rocks. Geochemical data have been used to classify the granitoids, to determine their chemical char acteristics, and to estimate the possible source regions and tectonic environment of magma generation and emplacement. The geochemical data indicate that these western margin granitoids range in composition fro m monzonitic to granitic-granodioritic varieties, belong to the alumin a-cafemic and cafemic associations and possess either a metaluminous o r peraluminous character. All granitoid types display features which m ay indicate the presence of both S- and I-type igneous rocks. Interpre tation of the trace element data suggests a syn-collisional to late/po st-collisional tectonic setting and a continental crustal source for t he granitoids.