Chemical composition of minerals and rocks from the 15°20'N Transform Fault, Atlantic Ocean

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.