Geology and Hydrothermal Alteration of the Chapi Chiara Prospect and Nearby Targets, Southern Peru, Using ASTER Data and Reflectance Spectroscopy

Autor(es)

Carrino, Thais Andressa ^[1] ; Crosta, Alvaro Penteado ^[1] ; Bemfica Toledo, Catarina Laboure ^[2] ; Silva, Adalene Moreira ^[2] ; Silva, Johann Lambert ^[1]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas, Inst Geosci, BR-13083870 Campinas, SP - Brazil

^[2] Univ Brasilia, Inst Geosci, BR-70910900 Brasilia, DF - Brazil

• Tipo de documento: Artigo Científico
• Fonte: ECONOMIC GEOLOGY; v. 110, n. 1, p. 73-90, JAN-FEB 2015.
• Citações Web of Science: 7

Resumo

Southern Peru contains several small- and medium-sized epithermal Au-Ag (+/- base metals) deposits related to Miocene-Pliocene metallogenetic belts. Specifically, the characterization of the geology and mapping of hydrothermal alteration zones of the Chapi Chiara prospect, Canahuire deposit, and Cerro Millo and San Antonio de Esquilache targets were done with data acquired by Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) spaceborne sensor. ASTER mapping techniques included (1) band ratio and principal component analysis (Crosta technique) applied to the visible and near-infrared and short-wave infrared bands to produce a regional hydrothermal alteration map (alunite and/or kaolinite, illite-muscovite and/or smectite, iron-bearing minerals) and (2) spectral indices and selective principal component analysis applied to the thermal infrared bands to detect quartz- and carbonates-bearing targets, respectively. These methods were used to establish a hydrothermal zoning pattern in paleostratovolcanoes, where the Chapi Chiara, Cerro Millo, and San Antonio de Esquilache targets are located. This zoning pattern was used to infer erosion conditions and the potential for metal deposits based on the mineralogy, which was also analyzed using reflectance spectroscopy and petrography. In addition, ASTER data were used to characterize the carbonate host rocks, the quartz-bearing units of the Yura Group, and the quartz-poor unit associated with the phreatic and phreatomagmatic breccias in the Canahuire deposit region. This characterization led to the development of a favorability model for the occurrence of ``Canahuire-type{''} deposits based on spatial analysis using the fuzzy logic technique. (AU)

• Processo FAPESP: 11/00106-8 - Geologia e alteração hidrotermal do prospecto aurífero chapi chiara e adjacências, sul do peru, a partir de dados geológicos, de sensoriamento remoto, geoquímicos e magnéticos
• Beneficiário: Thais Andressa Carrino
• Modalidade de apoio: Bolsas no Brasil - Doutorado