Resumo

LASTRA-RIVERO, José Francisco  e  GARCIA-CRESPO, Maria Elisabet. Factor analysis and multifractal concentration-area modeling for the delimitation of complex pedogeochemical anomalies in the Loma Roja-Loma Hierro sector, Western Cuba. Bol. geol. [online]. 2022, vol.44, n.2, pp.145-160.  Epub 18-Jul-2022. ISSN 0120-0283.  https://doi.org/10.18273/revbol.v44n2-2022007.

The Loma Roja-Loma Hierro sector is located in the northern part of the Dora-Francisco metallogenic district, Northwestern Cuba. This study was aimed at delimiting the complex pedogeochemical anomalies related to Sedex-type mineral deposits through the combined application of factor analysis and multifractal modeling. The analytical results of 1801 soil samples were used, those selected correspond to different indicator and pathfinder elements (Ag, As, Ba, Bi, Cu, Pb, Sb and Zn). Prior to the application of statistical methods, the conversion of closed to open data was required by means of an additive log-ratio transformation (alr), to avoid the correlations between the elements that were spurious. The application of correlation analysis and factor analysis to these transformed geochemical variables allowed us to define the links between indicator and pathfinder elements, as well as to obtain two complex geochemical variables, each one of them representative of a certain style of mineralization. The scores assigned to these complex geochemical variables were converted to values in ranges [0-1] using a fuzzy logistic function. The estimation of the anomalous thresholds was derived from the concentration-area diagrams generated from the application of fractal analysis to the transformed complex geochemical variables, previously interpolated with ordinary kriging. The multi-elemental geochemical maps show two mineralized zones with distinctive characteristics: one located to the north represented by pedogeochemical anomalies of Bi-Cu-As, associated with the roots of quartz-cupriferous stockwork, and another located in the southern half with pedogeochemical anomalies of Ba-Ag-Zn-Sb-Pb, related to pyrite-polymetallic stratiform mineralization.

Palavras-chave : Sedex deposits; Pedogeochemical anomalies; Compositional data analysis; Log-ratio transformation; Factor analysis; Multifractal modelling.

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