CALFRAC: Programa que quantifica o processo de cristalização fracionada e sua aplicação ao estudo de soleiras da Bacia do Paraná (Estado do Paraná) / CALFRAC: Program to quantify fractional crystallization processes and your application in the study Paraná Basin sills (Paraná).

AUTOR(ES)

Luciano Galdino

DATA DE PUBLICAÇÃO

2010

RESUMO

CALFRAC is a computer program written in C++ programming language developed to quantify fractional crystallization processes in igneous systems. Major, minor and trace element concentrations are used as input for calculations. The new algorithm enhances and makes the program more efficient than those published in the literature. Besides it is capable to automatically calculating all possible rock sample combinations involving differentiation by fractional crystallization process, using in addition trace element concentrations to corroborate the results obtained by the fitting of major and minor element abundances. CALFRAC calculates the total fraction subtracted from the original magma and the percentage of each fractionated mineral by solving least-squares mass balance equations based on major and minor element concentrations. The methods of maximum likelihood estimate and Lagrange multipliers are used to solve the equations, whereas for the quantification of trace elements the program uses the Rayleigh Equation. In both cases the mean relative percentage errors is used as an indication of the best results. The program CALFRAC was applied to investigate the possibility of differentiation by fractional crystallization of diabase samples from Paraná Basin sills, which outcrop nearby Salto do Itararé, Ponta Grossa, Prudentópolis, Rebouças, Irati, Reserva and Jaguariaíva towns (PR). The 33 collected samples were analyzed for major, minor and trace elements, including rare earths, employing X-Ray Fluorescence and Neutron Activation methods. The program output was not satisfactory, since it was not possible to establish a differentiation sequence from the more primitive to the more differentiated rocks of the intrusions. This is probably due to the fact that many rock samples are the result of mixing of magmatic melts with mineral accumulation zones, which were formed by the in situ fractional crystallization process.

ASSUNTO(S)

análise por ativação neutrônica computer program cristalização fracionada fractional crystallization major and minor element modeling modelagem de elementos maiores e menores modelagem de elementos traços neutron activation analysis paraná magmatic province programa computacional província magmática do paraná sills soleiras trace element modeling

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