Prospecção geológica e geofísica das ocorrências de Cu-Fe-P do tipo IOCG, borda oeste do arco magmático de Santa Quitéria, Ipaporanga/CE

Abstract

IOCG type deposits attracts much attention from academia and the mining companies, because in addition to an interesting mineral association, form high tonnage deposits. On the western border of the Magmatic Arc of Santa Quiteria there are some ore occurrences of Fe-Cu-P which show similar characteristics to this type of deposit. This dissertation aims to describe the geological characteristics of the ore to classify it or not, as IOCG, in addition to an assessment of the prospective potential using geological and geophysical data of the magnetometry and induced polarization. Host ore rocks consist of metarhyolites, metabasalte-andesites, albitized metadiorites, gabros, belonging to the Estreito Unit, which are interspersed with gneisses with garnet and calcissilicates of Canindé unit, cut by biotite granite, diorite porphyritic, whose age remains to be seen. Depending on the host rock and ore type, can be classified occurrences in five distinct types, which can have different genesis: 1) apatite-magnetite ore stratabound; 2) magnetic-apatite ore, isotropic fine-grained; 3) disseminated ore and veins in quartz dioritic intrusion hydrothermalized; 4) massive hematite ore formed by hematite; 5) massive magnetite skarn type ore. The geophysical data were of great use to perform the analysis of the prospective potential, since most of the rocks and minerals are covered by unconsolidated sediments of Ibiapaba Sierra. Considering the types of ore integrated geophysical methods allowed to select possible areas of concentration of three types of mineralization, according to the following parameters: anomalous high values of chargeability and magnetometry may be related to rocks composed of sulfides disseminated copper and iron with associated magnetite; Anomalous high values of chargeability can only be related to disseminated sulphides bodies of copper and iron nonmagnetic; anomalous high values of magnetometry must be associated only with the presence of polarizable weakly magnetic minerals. The geological characteristics of the five types of mineralization enriched in iron suggest that mineralization are owned there is a magmatic/hydrothermal system IOCG type and skarn. The geophysical 3D environment showed that the induced polarization anomalies have lateral continuity following the preferred direction N-S. There are also massive hematite bodies that are not detectable by geophysical methods because hematite not polarize and is not magnetic, making the area even more interesting there be prospected. To confirm the potential of the study area, an initial drilling campaign is necessary to intercept the main geophysical anomalies, thus identifying anomalous sources.