STATISTICAL ANALYSIS OF GEOCHEMICAL DATA: A TOOL TO DISCRIMINATE THE ORIGIN OF KAOLIN DEPOSITS IN PATAGONIA, ARGENTINA

CRAVERO FERNANDA; MARFIL SILVINA; MAIZA PEDRO

CLAY MINERALS (PRINT)

MINERALOGICAL SOC

Año: 2009

0009-8558

The numerous kaolin deposits located in Patagonia, Argentina, have been formed by hypogene or supergene processes. The primary origin has been established from O18 and D isotopic composition of the main minerals, kaolinite and/or dickite and from the behavior of certain elements during the alteration. The aim of this paper was to find if there is a tool, other than oxygen-deuterium data, to discriminate the origin of Patagonian kaolin deposits. To handle the large amount of variables per sample, a statistical multivariate study was used. The Principal Component method permits defining, on one hand the variables that better characterize each deposit and, on the other hand, the correlation between them. Once worked with the 57 elements, those that were not explained in the first two components (which represent 75% of the total variance of the model) were discarded. Therefore, the contents of Fe2O3, P2O5, LOI, Sr, Y, Zr, V, Pb, Hf, Rb, S and REE were used. The results show that the first two components separate the deposits in two fields that are consistent with the process of formation. The first component indicates that Fe2O3, Y, Rb, U and HREE are more abundant in the supergene deposits, whereas, Sr, Pb, S and V are more abundant in the hypogene ones. The second component shows that S, P2O5 and the LREE are enriched in the hydrothermal deposits, whereas Zr is more abundant in those formed under weathering conditions.