This study presents structural data undertaken during geological mapping (1:2.000) on
an area of about 5 km2 located on the Projeto Predra Branca do Amapari (AP), under
the Anglo Ferrous mining control. The research was based on structural mapping
(geometrical and kinematics analysis). The regional tectonic framework is
characterized by sets of holomorphic folds starting, in the E of the region, with a
isoclinal synform plunging 15/340 with flanks dipping moderately towards SW. This set
shows a NE vergence (mass flow from SW towards NE). Towards SW occurs a
kilometer-scale open antiform, showing low-angle parasitic folds (M geometry). Two
main iron-rich rocks are identified on the mines: (1) continuous milimetre-scale banded
rocks with typical silica/iron intercalations; these rocks are folded in parasitic sets
suggesting a flexural folding mechanism. The second rock type is characterized by
(2) an anastomosed myloniic foliation, NW-SE oriented, with dips that vary from 20° to
subvertical . The folds on the foliation show low-angle plunges (subhorizontal to 20°)
towards NW. A later ductile brittle E-W shear zone cuts all the mine rocks. Pegmatite
bodies are present in almost all the rocks. They are very irregular im shape, reflecting
their late emplacement along dilational spaces formed due the deformation of the
rocks. At the end of this work, a geometrical and kinematics model is presented based
on the partially sheared fold flanks, in different scales.
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