WHOLE-ROCK AND MINERAL CHEMISTRY OF MAFIC CUMULATES FROM THE LOW-Ti OPHIOLITE IN THE SOUTHERN PART OF KAHRAMANMARAS, TURKEY
M. Tanirli, T. RД±zaoДџlu
Kahramanmaraş Sütçü İmam University, Department of Geological Engineering, Kahramanmaras 46100, Turkey
Keywords: Suprasubduction, Low-Ti ophiolite, cumulate, KahramanmaraЕџ, Turkey
Abstract
A Late Cretaceous dismembered ophiolite unit in the south of Kahramanmaraş belongs to the Peri-Arabian ophiolite belt in southern Turkey. The ophiloitic rocks include, from bottom to top, metamorphic sole (plagioclase-amphibole schist and plagioclase amphibolite), mantle tectonites (serpentinized dunite and harzburgite), ultramafic cumulates (mainly websterite), mafic cumulates (olivine gabbro, gabbro, and olivine gabbronorite), and isotropic gabbros (olivine gabbronorite). The whole-rock geochemistry of the cumulates suggests that they can mainly be classified as Low-Ti ophiolite and cumulate rocks derived from an island-arc tholeiitic magma source. Chondrite-normalized REE and N-MORB-normalized multielement patterns and tectonomagmatic discrimination diagrams show that fractional crystallization was important during the formation of the cumulate rocks. The presence of highly magnesian olivines (Fo78.24-81.89), clinopyroxenes (Mg#71.46-85.82), and orthopyroxenes (Mg#62.63-87.18) as well as highly calcic plagioclases (An81.88-97.40) in the mafic cumulates indicates a subduction-related tectonic environment. The geochemical, petrographical, and field data suggest that the ophiolitic rocks in the studied region formed in a suprasubduction zone environment in the southern branch of Neotethys in the Late Cretaceous.
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