Petrology and geochemistry of the late Mesozoic Dzheltula alkaline igneous complex, Aldan–Stanovoy Shield, Russia: constraints on derivation from the ancient enriched mantle source

Petrological, whole-rock major and trace element, and Sr–Nd–Pb isotopic data are reported for the late Mesozoic Dzheltula alkaline igneous complex in the Aldan–Stanovoy Shield, Russia. The alkaline rocks are emplaced into the Tyrkanda mélange zone. The Dzheltula complex consists of monzonites, foid monzonites, and alkaline syenites; granite dykes intrude the complex. All alkaline rocks have high LILE contents (e.g., Ba and Sr), high light REE/HFSE ratios, strongly fractionated REE patterns, and typically lack Eu anomalies. Granite shows different major and trace-element characteristics in comparison to monzonites and syenites. The major and trace-element characteristics of the Dzheltula complex rocks and minerals are consistent with formation by combined assimilation and fractionation processes of an alkaline parental magma of lamproitic composition. The alkaline rocks have moderately radiogenic Sr ( 87 Sr/ 86 Sr( t ) = 0.7057–0.7065) and unradiogenic Nd ( ɛ Nd( t ) = − 11.3 to − 15.2) and Pb ( 206 Pb/ 204 Pb = 17.17–17.26); granite has more enriched 87 Sr/ 86 Sr( t ) value (0.707408) but similar ɛ Nd( t ) = − 12.93 The trace element and Sr–Nd–Pb isotopic data for the Dzheltula complex indicate its mantle source experienced ancient metasomatic enrichment, probably associated with subduction.