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Fig. 33 | Progress in Earth and Planetary Science

Fig. 33

From: The Atlantis Bank Gabbro Massif, Southwest Indian Ridge

Fig. 33

Pyroxene-poor harzburgite and dunite samples from Atlantis Bank indicative of late-stage melt transport in the shallow mantle. a Deeply weathered, pyroxene-poor harzburgite cut by a stockwork of olivine gabbro veins from Dredge JR31-6 on the northern secondary detachment fault surface (Fig. 3). All olivine is altered to orange clay, whereas the plagioclase in the veins appears to be altered to prehnite and hydrogrossular garnet. b Talc schist with enclaves of deeply weathered, pyroxene-poor harzburgite from the normal fault face on the eastern flank of Atlantis Bank at 57° 21′ E (Fig. 29b). The paragenesis is that of high-temperature fault gouge initially intruded up a shear zone due to formation of talc with infiltration of water into the mantle above serpentine stability field with subsequent serpentinization. c Cobble of massive statically serpentinized harzburgite crosscut by dunite dredged from the intersection of the primary detachment fault with the 57° 18′ E Normal Fault face on the eastern edge of the wave-cut platform (Fig. 3). d Dunite block with local spinel stringers cut by a metagabbro vein from 46 m below the gabbro-mantle contact high on the transform wall at 54° (Fig. 44)

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