Late Cretaceous coeval acidic and basic magmatism,Karacaali Magmatic Complex,Central Anatolia,Turkey

The Central Anatolia Crystalline Complex (CACC) is characterized by Late Cretaceous high-temperature metamorphic rocks intruded by S-, I-, and A-type granitoids. Coeval basic plutonic and volcanic rocks also crop out in the complex. The NE–SW-trending Karacaali Magmatic Complex (KMC) represents a clear example of synchronous basic and acidic magmatic associations. We present new data on this coeval magmatism. The KMC plutonic rocks mainly consist of monzonite, granite, and gabbro, whereas the associated volcanic rocks are chiefly of basalt and rhyolite. All of the units have been cut by quartz, quartz-tourmaline, and calcite veins and by porphyritic leucogranite, aplitic, and basaltic dikes. The rhyolitic, basaltic, and gabbroic samples yield well-defined ⁴⁰Ar/³⁹Ar plateau ages of 69.1 ± 1.3, 58 ± 10, and 66.4 ± 1 million years, respectively; these data indicate that a younger multiphase basic magma was injected into a partially crystallized monzonitic magma chamber. The basic intrusions added heat to the system and gave rise to the re-fusion of the already crystallized parts of the monzonitic melt, forming the younger leucogranitic magma. The gradational contacts, cross-cutting relationships, trace element contents, trace element patterns, rare-earth element (REE) patterns, and ⁴⁰Ar/³⁹Ar geochronological data of the studied igneous suite clearly demonstrate that the acidic and basic rocks of the KMC were contemporaneous and are produced by partial melting of distinct sources rather than by fractional crystallization of a single source.