17:15 〜 19:15
[SGC37-P15] A geochemical study on mantle xenoliths from the eastern Mediterranean: constraints from noble gas isotope systematics
キーワード：mantle heterogeneity, noble gases, mediterranean
Mantle xenoliths provide a crucial mean of characterizing the mantle, particularly in the Mediterranean region, and offer insights into processes such as wehrlitization, which contributes to CO2 production and release to the atmosphere. In order to characterize the mantle composition in a regional scale, this study focuses on noble gas systematics of the mantle xenoliths from NW Turkey.
NW Turkey is an active continental extensional setting characterized predominantly by transcurrent fault systems. Extension related tectonic and magmatic activity in the region is attributed to lithospheric thinning and asthenospheric upwelling. Mantle-derived ultramafic xenoliths carried to the surface by the Late Miocene mafic alkaline magmas have been identified in a number of localities. These xenoliths are represented mostly by refractory spinel-harzburgites and dunites with a smaller amount of relatively fertile spinel-lherzolites believed to represent the uppermost mantle layer at depths of less than 100 km (Aldanmaz et al. 2005).
This preliminary study involves noble gas isotope systematics (He, Ne, Ar) of 10 mantle xenoliths, including lherzolites and harzburgites. The results indicate a significant variation, particularly in helium isotope ratios (R/Ra), which range from 2 to 7 Ra, the high values being typical of the Sub Continental Lithospheric Mantle (SCLM; 6.1±0.9Ra). In contrast, the isotopic ratios of neon and argon do not remarkably differ from the standard air values, with the exception of a few cases where 40Ar/36Ar peaks just below 700 (air: 296).
Results will be interpreted in light of ongoing analyses of major and trace elements on minerals coupled to the radiogenic isotopes. Above all, an innovative, a detailed investigation of the internal structure of individual minerals (by using X-ray microtomography) can contribute to a comprehensive geochemical characterization of these mantle materials and elucidate how the internal structure of the minerals can play a key role in the interpretations of the origin of the volatiles trapped in minerals of the Earth‘s mantle (e.g., origin of the atmospheric contribution: deep vs shallow sources). Establishing a similar database for this area will provide a valuable reference for future research, enhancing our understanding of mantle heterogeneity, volatile cycling, and magmatic processes in the Mediterranean. The results of this study will offer a new perspective on mantle dynamics and volatile behavior in northern Turkey, a region of considerable scientific interest.
NW Turkey is an active continental extensional setting characterized predominantly by transcurrent fault systems. Extension related tectonic and magmatic activity in the region is attributed to lithospheric thinning and asthenospheric upwelling. Mantle-derived ultramafic xenoliths carried to the surface by the Late Miocene mafic alkaline magmas have been identified in a number of localities. These xenoliths are represented mostly by refractory spinel-harzburgites and dunites with a smaller amount of relatively fertile spinel-lherzolites believed to represent the uppermost mantle layer at depths of less than 100 km (Aldanmaz et al. 2005).
This preliminary study involves noble gas isotope systematics (He, Ne, Ar) of 10 mantle xenoliths, including lherzolites and harzburgites. The results indicate a significant variation, particularly in helium isotope ratios (R/Ra), which range from 2 to 7 Ra, the high values being typical of the Sub Continental Lithospheric Mantle (SCLM; 6.1±0.9Ra). In contrast, the isotopic ratios of neon and argon do not remarkably differ from the standard air values, with the exception of a few cases where 40Ar/36Ar peaks just below 700 (air: 296).
Results will be interpreted in light of ongoing analyses of major and trace elements on minerals coupled to the radiogenic isotopes. Above all, an innovative, a detailed investigation of the internal structure of individual minerals (by using X-ray microtomography) can contribute to a comprehensive geochemical characterization of these mantle materials and elucidate how the internal structure of the minerals can play a key role in the interpretations of the origin of the volatiles trapped in minerals of the Earth‘s mantle (e.g., origin of the atmospheric contribution: deep vs shallow sources). Establishing a similar database for this area will provide a valuable reference for future research, enhancing our understanding of mantle heterogeneity, volatile cycling, and magmatic processes in the Mediterranean. The results of this study will offer a new perspective on mantle dynamics and volatile behavior in northern Turkey, a region of considerable scientific interest.