Evaluation of ore deposits potential in the Andahuaylas – Yauri Batholith

104 páginas. INGEMMET through its Resources Mineral and Energy Direction – Metallogenic Program, signed an international cooperation agreement with the Korean Geological Survey (KIGAM) with the purpose of evaluating the ore deposits potential in the Andahuaylas – Yauri Batholith. This investigation includes metallogenetic interpretations using geochronological, isotopic, petromineralogy, structural studies, as well as geochemistry of rocks and sediments. The importance of this area has increased over the years, during which many exploration works were carried out and consequently, many mineral occurrences have been discovered. Considered now as a probable extension of some copper belts of Chile (Perelló et al., 2003); nearly 70% of the area has been granted as mining concessions to different mining companies. Initially, this was considered exclusively a Fe-rich zone, but later on more detailed studies came to the conclusion that it hosts a series of ore deposits related to Cu – Au – Mo porphyry systems. The international cooperation project lasted approximately 9 months, and included three field trips. During this period, mines, projects, prospects and potential areas free from mining claims were evaluated. The Andahuaylas - Batholith domain was divided into two study subzones, known as “A” and “B”. One of the main areas in the subzone “A” was Cotabambas, where a series of porphyry deposits are located and are known collectively as the Cotabamba cluster. In the surroundings of this cluster, the Colca area was recognized, which has some potential to host an ore deposit. The geologic features are very similar to those of the Cotabambas cluster and small outcrops of malachite along fractures can be observed. Several mineral occurrences were visited in zone B, such as: Angostura, Santa Rosa de Virundo, Yuringa, Atacancha, San Diego, Lahuahi, Jara Jara, Utupara and the surrounding areas of Las Bambas. Within this subzone, the Jalaoca area was recognized as an important potential area. This is located about 8 Km west from the Mollebamba city, very close to the inactive mines of San Diego and Lahuani. Polymetallic vein-type mineralization (quartz – molybdenite – hematite – chalcopyrite – bornite and galena) has been identified, as well as stockwork structures with piryte and chalcopyrite probable related to porphyry deposits. Another interesting area in the subzone “B” was Supamarca. This occurrence is located on the left side of the Abancay – Andahuaylas road. Copper suphide mineralization and hematite in thin laminates associated with siliciclastic rocks such as the sandstones of Muñani Formation (Upper Cretaceous – Paleocene) have been identified. These occurrences share some common features with such copper occurrences in red beds in the eastern sector of the Andahuaylas – Yauri Batholith. This document presents new geochemical interpretations based on geochemical analysis of rocks and stream sediments. Geochemical graphic representation of major and trace elements give us an idea about the type of magmatism developed in the area and its associated potential. Isovaloric maps of stream sediments confirm the potential that some areas. Interpretation of the data that polished and thin sections offer, confirm the type of rock and magmatism in the area of study. Finally, using the isotopic data collected from different studies it related the isotopic signatures with the expected tonnage for some porphyry deposits. In this investigation, samples were collected from the Cotabambas cluster for isotopic and geochronology studies. Those samples are being currently analyzed at KIGAM laboratories (Korea). This INGEMMET and KIGAM joint work tries to gather all the information related to the Andahuaylas – Yauri Batholith, and to update the existing geological data with the new data obtained from the field and office work, with the final purpose of providing exploration companies a new regional tool that will help them to better conduct their exploration campaigns. Proyecto GE-24: Evaluación del Potencial de los Depósitos Minerales en el Batolito Andahuaylas – Yauri.