Olivine-rich Troctolites from Ligurian Ophiolites (Italy): Evidence for Impregnation of Replacive Mantle Conduits by MORB-type Melts

Melt/rock reaction at oceanic peridotite/gabbro transition as revealed by trace element chemistry of olivine

“…Similar textures have been already documented in ophiolites and in layered intrusions (e.g. O'Driscoll et al, 2007;Renna and Tribuzio, 2011), and interpreted as primary magmatic disequilibrium texture related to open-system episodic melt influx. Subsequent olivine-gabbro lenses and thin dykelets intruded both peridotites and troctolites, crosscutting the peridotite foliation and the magmatic layering in the troctolite body .…”

“…Similar granular to hopper to harrisitic textures in olivine are described in the literature in layered intrusions and ophiolites (e.g. Donaldson et al, 1982;O'Driscoll et al, 2007;Renna and Tribuzio, 2011), and are considered to result from opensystem processes causing variations in melt composition and, consequently, in the degree of undercooling (e.g. Faure et al, 2003).…”

“…Several lines of evidence have stressed that melt/rock reactions acting at the oceanic mantlecrust boundary play an important role in the chemical evolution of MORBs and the formation of the primitive (olivine-rich) lower oceanic crust (Bedard et al, 2000;Coogan et al, 2000;Drouin et al, 2009Drouin et al, , 2010Gao et al, 2007;Dick et al, 2008;Lissenberg and Dick, 2008;Kvassnes and Grove, 2008;Eason and Sinton, 2009;Godard et al, 2009;Collier and Kelemen, 2010;Renna and Tribuzio, 2011;Tribuzio, 2011, 2012;Lissenberg et al, 2013;Sanfilippo et al, 2013Sanfilippo et al, , 2014Sanfilippo et al, , 2015aSaper and Liang 2014). Specific chemical features in MORBs, such as the spread in MgO contents at given CaO values, cannot be easily reconciled with processes of fractional crystallization of heterogeneous parental melts occurring at variable pressure.…”

“…Parallel chemical and microstructural studies on olivine-rich intrusive rocks (troctolites, werhlites, olivine gabbros) from modern ridge settings and ophiolites (Lissenberg and Dick, 2008;Drouin et al, 2009Drouin et al, , 2010Renna and Tribuzio, 2011;Tribuzio, 2011, 2012;Lissenberg et al, 2013;Sanfilippo et al, 2013Sanfilippo et al, , 2014Sanfilippo et al, , 2015a have suggested a composite "hybrid" origin of these rocks, likely related to open-system melt impregnation of an olivine crystal…”

Experimental petrology constraints on the recycling of mafic cumulate: a focus on Cr-spinel from the Rum Eastern Layered Intrusion, Scotland

“…Similar recrystallized melt inclusions have been documented in layered intrusions and oceanic lower crust gabbro (e.g. Irvine, 1975;Arai et al, 1997;Spandler et al, 2005;Renna and Tribuzio, 2011). Spinel itself hosts recrystallized melt inclusions consisting of olivine, plagioclase, apatite and Ti-spinel.…”