Rapakivi Granites and Associating Magmatism during the Aptian Development Phase of the Siberian Craton Active Continental Margin (Northeast Asia).

New data on the U–Th–Pb geochronology, mineralogy, geochemistry, and Sm–Nd and Rb–Sr isotopes for granitoids and the associated subalkaline rocks of the Tarbagannakh pluton of the Allakh-Yun tectonic zone in the Verkhoyansk fold-and-thrust belt are presented. These rocks, including trachyandesibasalt dikes, combined into the Uemlyakh complex, were formed about 120 Ma from a continental crust source probably with input from an enriched mantle component. Rapakivi granites are reported for the first time among them; their origin is reference for understanding the geodynamic conditions of formation of rocks in this complex. A tectonic model for the formation of these rocks due to slab break-off during the development of the active continental margin in the Aptian age is proposed. It is discussed that this magmatism was conducive for the widespread development of metasomatic processes until the end of the Aptian age and was at the same time a source of the coinciding spatially gold mineralization of the Okhotsk–Koryak metallogenic belt. [ABSTRACT FROM AUTHOR]