The Ronda high temperature peridotite: Geochemistry and petrogenesis

摘要: Abstract The Ronda peridotite in southern Spain is a large (~300 km2) exposure of upper mantle which provides direct information about processes on scale much larger than that provided by xenoliths basalt. peridotites range from harzburgite to lherzolite, and vary considerably major element content, e.g., Al2O3 0.9 4.8%, trace abundances, Sr, Zr La abundances factors 20 40. These compositional variations are systematic correlate with (pyroxene + garnet)/olivine ratios olivine compositions. data consistent formation residual variable degrees melting (~0 30%) compositionally homogeneous peridotite. None the have geochemical characteristics residues formed extensive (⪢5%) fractional can be explained equilibrium (batch) melting, possibly incomplete melt segregation some samples. Based differences between peridotites, segregated melts were picritic (12–22% MgO) relative rare earth similar mid-ocean ridge basalt (MORB). Prior event body was suitable source for MORB. diapiric rise fertile relatively small near diapir-wall rock interface yielding garnet iherzolite, diapir interior garnet-free Subsequently these rocks recrystallized at sub-solidus conditions ( Obata , 1980), emplaced crust thrusting (Lundeen, 1978).