Uncertainty analysis in geophysical and remote sensing data acquired in the Tapajos gold province, Amazon, Brazil

• Grant number: 12/25479-4
• Support type: Scholarships abroad - Research Internship - Post-doctor
• Effective date (Start): February 25, 2013
• Effective date (End): May 24, 2013
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geophysics
• Principal researcher: Caetano Juliani
• Grantee: Cleyton de Carvalho Carneiro
• Supervisor abroad: Michael J. Friedel
• Home Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Research place: U.S. Geological Survey, Denver (USGS), United States
• Associated to the scholarship: 10/10498-8 - GEOLOGY AND GOLD METALLOGENY OF THE TAPAJOS PROVINCE, ITAITUBA REGION, PARA STATE, BRAZIL: APPROACH BASED IN AEROGEOPHYSICAL MAGNETOMETRY AND GAMMASPECTROMETRY IMAGES., BP.PD

Abstract

The Tapajós Gold Province, or Tapajós Mineral Province, is located in the South-Central part of the Amazon Craton. The geological and economic importance of this province can be highlighted by the production of gold in mines, which according to unofficial estimates, may reach more than 750 t. However, recently, were recognized in the province many occurrences of copper, lead, zinc and molybdenum in epithermal and porphyry types (Juliani et al. 2012), which increases the province mineral potentiality. Access to outcrops in the Tapajós region is limited by factors common in the Amazon, such as the presence of vast and dense vegetation and thick weathering mantle. The latest geological maps of this area were made in the 1:1,000,000, 1:500,000 and 1:250,000 scales in most part of the province (Almeida et al. 2000; Bahia & Frames, 2000, Ferreira et al. 2000 , Vasquez & Klein, 2000; Vasquez & Klein, 2000; Santos et al. 2000, Costa-Rosa Vasquez & 2008b). To compile these maps, in face of the difficulty of access, geophysical data with low spatial resolution and limited sampling density along the flight lines were used. However, studies of this approved postdoctoral have also used newer, higher sampling density data from the geophysical survey, which has led to the identification, by the technique Self-Organizing Maps, of a greater geological complexity, as well as changes associated with hydrothermal mineralization mentioned above. This project aims to complement the studies already made by the candidate, through the analysis of the uncertainty of the results obtained by the SOM technique, with different combinations of airborne geophysical and remote sensing variables in the Tapajós region. This analysis has fundamental importance for statistical validation of the lithogeophysical units already identified as well as areas of hydrothermal alteration associated with mineralization. The uncertainty analysis uses data already processed in previous phases of the postdoctoral project, which this sub-project is linked. It is expected, with the development of this work, to quantify the uncertainties related to geological information that support the advancement of the models of the genesis and evolution of the Tapajós Gold Province, as well as the origin and spatial distribution of mineralization and their associations with rocks. This project is part of the study involving the genesis and evolution of the Uatumã magmatism and the characterization of associated gold mineralization, in development by the supervisor's team. (AU)