Comportamento geoestatístico de ouro em solos e sedimentos de corrente associados às mineralizações auríferas da região de Princesa Isabel-PB.

Abstract

The present study deals with the geostatistical analysis of soil samples and auriferous stream sediments from the municipality of Princesa Isabel (PB). Gold occurs in quartz veins of Higher Formations metasedimentary of the Precambrian. This metal is currently being explored in the region and the large geochemical survey by CDRM / PB ended up discover new additional deposits. The large sample coverage of soils and sediments associated with the region's gold deposits yielded a large amount of data about the occurrences of this metal. The goals of this study were to verify the nature of the metal distribution in soil and sediment, know the geochemical behavior of the element, and also develop a systematic model of their distribution. From a total of 129 samples analyzed, gold present in sediments ranges from 0 to 184.71 ppb, with average value of 9.44 ppb, and variance high of 841.49. The coefficient of variation tends to fluctuate around 307.24%. Soil samples, 571 data were considered, with contents ranging from 8 ppb to 950 ppb, with average content of 52.08 ppb, variance of 10858.45 and variability irregular of 200%. The distribution of gold in soil and sediment assumes a lognormal behavior. Soil and sediment sample contents were used to develop the variograms, thus discovering the structure and continuity of the metal distribution. The average variograms elaborated did not show a very satisfactory structure, however, the Directional model indicated a good structure with a 7 m drainage sediments, and 1800 m, for soil. These variograms still showed a pattern hole effect with vertical oscillation where the curve represents irregular sedimentation and / or periodic regarding the occurrence of gold. The effect of removing samples with extremes was also investigated. Soil and sediment samples were grouped associated with each mineralized shaft to separate structures from the general variogram. This resulted in significant structures that showed the influence of mineralized veins gold distribution patterns in sediment and soil.