ALTERATION AND MINERALIZATION OF A LOW SULFIDATION SYSTEM TO A PORPHYRITIC CU-AU SYSTEM IN THE SAYAPULLO DEPOSIT TRUJILLO-PERU

The Sayapullo Epithermal Deposit is located NE of Trujillo-Peru. In the Chicama-Yanacocha structural corridor, which has generated a metallogenic strip where different porphyritic systems have been emplaced, one of them is the Sayapullo porphyry which, due to its Pb-Ag-Zn mineralization, is within a Low Sulfuration system. . Geologically it is located in a sandstone box rock of the Chimú geological formation, forming mineralized bodies of 10 to 50 cm of economic mineralization which is located in Galena-Esfalerita and Argentita. The alteration in the bedrock is weak to incipient since the samples taken with Terraspec and analyzed with the TSG software result in traces of Paragonite.

At the levels of the underground workings, there have been evidences of different intramineral pulses, of a calcosilicate nature, the early intramineral porphyries are of dacitic composition while the late intramineral porphyries and dikes are Rhyolitic, the samples taken for alteration assemblages resulted in an Alteration Phyllic with a Quartz-Muscovite+-Paragonite assemblage in the early porphyries, while the late porphyries have an Argillic alteration with a Montmorillonite assemblage and the dikes have a Propilitic alteration with Chlorite assemblage. The texture of the rock is porphyritic with hypidiomorphic crystals, in the early intramineral porphyries type B veinlets of Qz are observed. In the late intramineral porphyries it presents type D veinlets and in the dikes only Py dissemination is observed. The metallic mineralization is of Au-Cu which is concentrated in the intrusives, the Cu is in Cpy < 1000 ppm. Evidence suggests that there is a porphyritic system that is the generator of low sulfidation mineralization in the Sayapullo Deposit.