The aim of this work was to study petrography and mineralogy of mineral associations with magmatic high-Ti hornblendes and micas in MAR spinel harzburgite. It was found that these mineral associations had been formed in a temperature range of 870-950°C as a result of crystallization of a residual highly differentiated (96-98%) mantle magma and its interaction with host peridotite. Based on compositions of pyroxenes and amphibole, the initial mantle magma was in equilibrium with minerals of the restite harzburgite and based on its enrichment in LREE (La/Sm_n = 10-12) can be classified as intraplate OIB magma. Absence of the Sr anomaly in the model composition of the initial magma, evaluated for one of two MAR areas concerned (Site BP16-68), and the negative Sr anomaly characteristic of the model composition of magma, calculated for other MOR area (Site BP16-62), can serve as an independent confirmation of local rock heterogeneity in an region of intraplate magma generation, possibly associated with crustal component recycling.

Supplement to: Bazylev, B A; Silantyev, Sergey A; Dick, Henry J B; Kononkova, N N (2001): Magmatic amphiboles and micas in oceanic peridotites and some specific features of the related magmas: 15°20'N MAR Fracture Zone. Russian Journal of Earth Sciences, 3(3), 219-234