Petrographical and geochemical insights into gabbroic rocks in ophiolitic occurrences from Kınık-Kütahya (Türkiye)

Abstract

The ophiolitic rocks within the Tavşanlı zone offer valuable insights into the closure period of the Neotethys and subsequent geological processes. This study focuses on the petrographic and geochemical characteristics of gabbroic rocks from the Kınık Ophiolite in Kütahya, Turkey. Petrographic observations show that the main constituents of gabbroic rocks are plagioclase (labradorite, bytownite), orthopyroxene, clinopyroxene, and hornblende. Hydrothermal alterations such as uralitization, chloritization, and carbonization are commonly observed in ophiolitic rocks. The mafic rocks are part of a differentiated tholeiitic magma series, emphasizing their co-magmatic evolution within the context of the ophiolitic complex. Despite variations in Large Ion Lithophile Elements (LILEs; K, Sr, Rb, and Ba) due to low-temperature hydrothermal alteration (e.g., saussuritization of plagioclase, uralitization of pyroxene, and chlorite–prehnite vein formation), the geochemical signature of the Kınık gabbroic rocks suggests island arc tholeiitic (IAT) characteristics. Additionally, their rare earth element (REE) patterns strongly indicate a supra-subduction zone (SSZ) affinity. The development of the Kınık ophiolite, involving magmatic crystallization, occurred during the final stages of island arc evolution in the Neotethyan Ocean within a supra-subduction, fore-arc tectonic setting.