TRANSTRAÇÃO E TRANSPRESSÃO AO LONGO DO LINEAMENTO CINZENTO (REGIÃO DA SERRA DOS CARAJÁS)

Abstract

The sinistrai strike-slip Cinzento lineament is formed by compressional and extensional segments and represents a small fraction of the Itacaiunas shear belt. From west to east these structures are identified as the Igarapé Salobo extensional duplex, the Curuni compressional duplex and the Serra Pelada compressional horsetail. The eliptical geometry of the Igarapé Salobo structure is defined by a major normal shear zone mat converge to the E-W strike-slip detachment zone; the internal geometry consists of a set of NW-SE oblique normal Tones. Its kinematic evolution includes transtension followed by transpression and then transtension. The Cururu duplex is a rhomboedric structure related to E-W Y or D zones and NW-SE P zones interaction. Its internal geometry comprises oblique thrust zones linked to the major strike-slip zones, and its kinematic evolution involves transtension followed by transpression and strike-slip displacements. The Serra Pelada horse-tail includes NE-SW oblique thrust zone wich diverge from the master E-W strike-slip zone. Its kinematic history includes transtension, transpression and displacements in R* zones. Important deposits of gold, sulphides, rock crystal and amethyst are associated to the Cinzento lineament evolution.