Clinopyroxene thermobarometry of the Çatak pillow basalts, Maden Complex (Eastern Anatolia): Implications for magma storage and mantle melting
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Abstract
The tectonomagmatic affinity of the Maden Complex within the southeastern Anatolian orogenic belt remains debated, with interpretations ranging from intraoceanic arc and back-arc basin development to post-collisional and MORB-type mantle derivation. However, quantitative mineral-scale constraints on magma storage conditions are limited. This study presents new clinopyroxene major-element data from submarine pillow basalts exposed in the Çatak area (Eastern Anatolia) and applies established clinopyroxene-based thermobarometric formulations to constrain crystallization pressures and temperatures. Clinopyroxenes are compositionally restricted to the augite field and display moderate Mg# values (≈ 68–77), with negligible calculated Fe³⁺ contents, indicating relatively reduced crystallization conditions. Discrimination diagrams show dominant E-MORB to ocean-floor basalt affinities, without systematic Ti depletion, typical of strongly fluid-fluxed arc-front settings. Thermobarometric calculations yield crystallization temperatures of ≈ 1100–1190 °C and pressures predominantly between ≈ 4–8 kbar, consistent with intermediate crustal magma storage conditions. The inferred pressure–temperature regime is compatible with crystallization from basaltic melts derived from spinel-facies mantle sources proposed in previous regional studies. Integration of mineral chemistry and thermobarometric data suggests magma evolution under transitional MORB-like to supra-subduction extensional conditions. These results provide new quantitative constraints on the mantle melting regime and magma storage depth in the Çatak segment and support the interpretation of tectonomagmatic heterogeneity within the Maden Complex.
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