This work intention is to stand out a sistematic study on the chemical elements dispersion in soils and duricrust, developed over, diversified geological environments lithotypes, under humid tropical climate in the Amazon region-. Two target areas were chosen for soil sampling( Serra dos Carajás-N-5 and Serra do Tiracambu TN-6); the former, a gibbsite rich latosoil, is situated in the southwest part of Pára State; the latter, has a predominartee- of kaolinite and iron oxi-hydroxides overling a bauxite layer, situated in the western border of Maranhão State. Two other areas were selected for duricrust studies, Pirocaua iron-phosphate crust, surrounded by latosoil ( NW of Maranhão State) and Serra dos Carajás target N-1 feruginous crust. The methodology assumed was the same for all targets for both soil and duricrust, as follow: a - sampling grid of 200x200m; b - Three parts separation of soil samples (bulk,<200-14 and -80-F200- mesh- )-for duricrusts were only considered bulk samples; - X-ray difratometric analysis were carried out to determine mineralogical composition and atomic absortion for determination of Ni,Co,Cr,Cr,Mn,V,As and Bi and, Au, through fire assay; d X-ray fluorescence analysis were taken for SiO2,Fe2O3,Al2O3,TiO2,Ba,Y,Nb,Zr,Ga and Sc; PGE (Pt,Pd,Rh) and REE analysis were obtained by aplicai emission spectrography after pre concentration and ICP, respectively. Mineralogical and chemical data were processed in order to obtain basic statistical parameters by using compatible PC-IBMIXT through Geoquant System CPRM 3.1 version, as well as some other complementary softwares CONVERT and QPRO) both in the statistical studies and graphic data display, besides CLUSTER R MOD and Q MOD analysis. Target TN-6 X-ray difratometry soil samples analysis showed a mineralogical homogeneous character as predominantly composed by kaolinite,A1-goethite and anatase. This homogeneity is also present in bulk sample chemical composition and in the analized fractions as well,revealing a distribution of three main geochemical association-SiO2-Al2O3-Cu-Mn-Sr; Fe2O3-V-Cu-Ba-Cr-As-Sc-REE and TiO2-Y-Nb-Zr-Ga-Sc-REE as a reflect of kaolinite, iron oxi-hydroxide and anatase,respectively. On the other hand target N-5 latosoils are made out by gibbsite followed by goethite-hematite and in minor content, kaolinite and anatase. Although this target, from the mineralogical point of view, does not present much difference from the TN-6 except for the presence or gibbsite, it outstands the association of TiO2- Al2O3-Ga-Zr-Sc-Sr as well as Fe2O3-Mn-V-Cr-Sc-As. The former association representing gibbsite and anatase, besides being more consisterrt, surrounds the Fe2O3 association wich in turn reflect iron oxi-hydroxides and, indirectly, the contribution of basic rocks in the latosoils origin. Regarding target N-1duricrust, which presents differents textures (stratified,pisolitic and cavernous), the results obtained showed independently, similar concentration for Mn, Sr,Nb and Ga. Small difference characterize the cavernous duricrust in the gibbsite content and the predominantly presence of Au and Pt. In target N-1, as a whole, the most significant geochemical association was defined by Al2O3-TiO2-Cr-V-Sr-Nb-Zr-Ga-Sc-As. Low concentration of trace elements in this association reflects its origin from sedimentary nature Fe-Mn silicate deprived rocks, with low mafic/ultramafic contribution correlation matrix and groupment analysis in the Pirocaua target stablished two great geochemical associations with equal importance for soils and duricrust. The first, Fe2O3-V-Ga-Ni-Cu-Cr-As, indicates iron minerais, chiefly goethite and hematite, while the second, P2O5-Al2O3-(TiO2)-Sr-Y-Zr-REE reflects the crandallite-goyazite group of phosphates. The iron association is more frequent, occuping great extension of the plateau, not discerning soils or duricrust. So does the Au disperssion which presents indistinctly qualified values for 13 samples averaging 0.2 ppm and 1.01 ppm as maximum value. Arsenic concentratiton achieved an average of 188 ppm in duricrusts and 273 ppm in soils to which are associated the presence of tourmaline (dravite) in soil derived from hydrothermal zones noticiable in some outcrops fractures. Regarding PGE,qualified values for PT ( 0.1 to 0.4ppm) are directly associated to high concentration of Cr ( 1235 ppm in duricrust) and high values of P2O5 ( 11.85% soil to 15.05%-duricrust), this geochemical landscape is an evidence a basic composition vulcanosedimentary bedrock, rich in phosphates for the Serra do Pirocaua. The studies carried out were important in characterizing soils and duricrusts under a geological, mineralogical and chemical pooints of view, considering that, in both sample categories a surface sampling reflects, till certain extent and accuracy, trough geochemical association, the bedrock nature from which these covers had derived, as observed in the Pirocaua and N-5 targets the contribution of basic rocks as well as in the TN-6 and N-1 sedimentary rocks influence. This fact shows an importance to.consider.in the geochemical surveys, in characterizing concealed bedrock lithotypes by sampling their autochthonous covers, developed under humid tropical climate regions as the Amazon, taking into account that these rocks are not easily identified due the morphological condition involved and the consequent thicknes of the overburden. This is most outstanding inasmuch that the widrespread distribution frequency of those lithotypes in this region plus the scarcety of outcrops and their relationship to host environments of mineral deposits.
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