Linked from
The 13 pages that link to Gabbro, each with the reason it gives.
Oceanic crustRelated: Gabbro forms much of the lower crust beneath the basaltic lavas.
PyroxeneRelated: Its abundant pyroxene records slow crystallization deep in the crust.
AmphiboliteRelated: Gabbro is another common mafic protolith for amphibolite.
AugiteRelated: Visible augite crystals commonly occur with plagioclase in gabbro.