A fragment of inherited Archaean lithospheric mantle rules the metallogeny of central Mexico

Abstract

ABSTRACT Mantle xenoliths from Santo Domingo, Ventura-Espíritu Santo and Durango volcanic fields (Mesa Central in Mexico) experienced low degrees of partial melting in the stability fields of garnet (⁓ 2%) and spinel peridotites (⁓ 2–4%), and interacted with hydrous alkaline melts possibly during the Basin and Range extensional tectonism since Late Oligocene. Enclosed and intergranular grains of monosulfide solid solution (mss) in Santo Domingo peridotites are residues after the extraction of 0.1–0.5 fractions of Ni-Cu-rich sulphide melt during mantle melting events. On the other hand, glo˜bular sulphides (pentlandite ± chalcopyrite) hosted in glass veinlets in the Ventura-Espíritu Santo and Durango peridotites crystallized from Ni-Cu-rich droplets of sulphide melt, immiscible in the Quaternary silicate magmas that brought the xenoliths to the surface. Rhenium-depletion model ages of these sulphide populations indicate that part of the subcontinental lithospheric mantle (SCLM) of the Oaxaquia terrane (beneath Santo Domingo and Ventura-Espíritu Santo) originated in the Archaean-Paleoproterozoic as the southernmost extension of the Laurentia craton, and was assembled with the Central terrane (beneath Durango) during the Grenville orogeny (⁓ 1.0 Ga). Early Palaeozoic (⁓ 500 Ma) model ages common to sulphides from the peridotite xenoliths of the three volcanic fields suggest that the Oaxaquia-Central composite block split away from North America during the Rodinia break-up and experienced the Pan-African-Brasiliano orogeny that led to Gondwana assembly. During the Cenozoic, the reactivation of translithospheric faults bounding this composite old SCLM provided preferential pathways for focusing the ascent of ore-productive magmas/fluids associated with the subduction-related metallogeny of the Pacific active margin of Mexico.