Detrital peridotite minerals reveal recycled arc mantle beneath Marion Rise, Southwest Indian Ridge

The recycling of subcontinental lithospheric mantle back into the asthenosphere during continental breakup is potentially a major but underappreciated process in plate tectonics. Here, we report major and trace elements for detrital peridotite minerals in carbonate breccias dredged from the Marion Rise, Southwest Indian Ridge. With an emphasis on the trace elements of the relatively abundant orthopyroxene detrital grains, the results show that a portion of pyroxene grains was likely derived from a mantle source that experienced hydrous melting and slab-derived melt metasomatism above a subduction zone. This finding provides a novel view into the mantle geochemistry at midocean ridges, as well as evidence that Marion Rise is at least partially supported by chemically buoyant recycled refractory mantle wedge material.