Structural control and timing of evaporite-related Mississippi Valley-type Zn–Pb deposits in Pucará Group, northern central Peru

Abstract

The South America MVT belt comprises the deposits of San Vicente, Shalipayco, Florida Canyon, and some minor Zn–Pb occurrences hosting in the carbonates and evaporites of the Pucará Group, in an extension of more than a thousand kilometers from the center to the north of Peru. Structural constraints of the MVT Peruvian deposits are conditioned by deep sub-vertical secondary extension structures with general N, NNE or NNW direction related to strike-slip movements superimposed on previous Andean NW thrust structures. Recent studies on Shalipayco and Florida Canyon deposits point to similar processes of rock formation, diagenesis and mineralization acting in province scale. New isotopic data of Pb–Pb and Rb–Sr in sulfides summed with a compilation of the available data for the evaporite-related MVT deposits and studies on the structural and tectonic evolution of the Peruvian Andes allowed establishing correlations of local process of the deposits to the regional Andean tectonic events. The Florida Canyon saline dome structure was attributed to Juruá Orogeny (157–152 Ma). The stage of dolomitization forming the porous dolostone and evaporite breccia during burial diagenesis is attributed to the period between Juruá and Mochica stages. The oil migration to these reservoir rocks occurred probably during Mochica event (100–95 Ma). The Rb–Sr dating of sphalerite from the Florida Canyon deposit together with temporal field relations indicated that the Zn–Pb sulfide ore formed in or just after Peruvian Orogeny (86-83 Ma).