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The paper presents the first data on geochemistry (major and trace elements, isotopes) of the Late Devonian–Early Carboniferous basalts of the Char suture-shear zone in East Kazakhstan, and includes detailed analysis of their geological relations and petrogenesis (fractional crystallization/melting modeling). Three groups of oceanic basalts coexist in the Char zone. Group 1 basalts are associated with oceanic siliceous sediments and have medium TiO2, relatively flat REE patterns (La/Smn = 0.7, Gd/Ybn = 1.3), Zr/Nbav. = 42 and eNdav. = 6.3. They formed at high degrees of melting of a depleted mantle source and were erupted in a mid-oceanic ridge setting. Group 2 basalts are associated with both chert and carbonate and have higher TiO2, Hf, Y, Zr and P2O5 than the rocks of Group 1. They are similarly characterized by low Nb (Nb/Lapm 2) stability fields. They possibly represent fragments of oceanic islands/seamounts formed in relation to mantle plume. |
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