Determinación e incidencia del fondo geoquímico de las pizarras areniscosas del Tremadociense sobre las concentraciones minerales. Zócalo de la rama sur de la Ibérica. (Prov. de Soria y Zaragoza)

Abstract

The metallogenic study carried out in the upper formations of the Tremadocian on the occidental branch of the bedrock of the Iberian Range, has allowed us to classify as sinsedimentary - epigenetic many of the mineral occurrences of Pb, Cu, Zn, Ag and Sb present. As these occurrences are associated with the sandy shales ("micropsammofilitas-psammitas"), their geochemical background (in Pb, Cu, Zn, Ag and Sb) could be determined as well as their infIuence on the concentration of minerals present. The elements, were anaIysed in more than 240 sandy shales fram: La Alameda (Soria); Embid de Ariza, Bubierca and Pardos (Zaragoza). The background on these clements was shown to be higher than that of the sandstones; compared with the shales, the concentration of Pb and Zn was slightly higher (16-25 p.p.m. and 92-115 p.p.m. respectively) and substantially so in the case of Ag (0.31-0.77 p.p.m.) and Sb (6-15 p.p.m.). The concentration of Cu was the same. The Iines of regression corroborate the evidence of the metallogenic studies. The geochemical metallotect, together with the tectonic and stratigraphical metallotects represent necessary, but not sufficient conditions to justify the mineral concentrations in La Alameda and Bubierca; we must also employ the paleogeographical metallotect resulting in the formation of shallow.