A megafalha de Cubatão no sudeste brasileiro

Abstract

The Cubatão Megafault System represems an extensive strike slip system exposed along about 800 km wilh a minimum breadth of about ISO km and a maximum oC 350 km wben considered as part oC the Socorro-Guaxupé thrust wedges. The maio fault zone is represented by the Cubatão-Além Parafba and Lancinha faults. lhe enension of tbis faull zone has been detected beneath the sediments oC lhe Paraná Bas.in for ai leas! an additional 1,200 km impl:ying a lenglh of more then 2,000 km, which is longer than lhe San Andreas fault. The fault affects difl"erent structural leveis of the crust and has exhibited different behaviour throughout its history of activity. lt was essentially ductile at depth during lhe Proterozoic where deep granulites were dragged about 40 km along the Além ParaIba fault segmento The mylonites are Colded and shaw an overprinted schistosity marked by neocrystallized biolites of Proterozoic age. The draga shaw the effect of rigbt lateral IUncmatics during this phase; however left lateral activation is suggested by the distribution of a pattem of secondary faults related 10 later events. The faull .system is offset aI its intersection with the NW striking Guapiara, Ubatuba and Cabo Frio-Poços de Caldas Lineaments. The Cubatão fault sensu .strictu shows a controversial thrust·strike s.lip pair envolving a wedge oC low grade metamorphic rocks. Oblique slip and transtensional basin formation envolved lhe fauIt system during the Tertiary and originated lhe Serra do Mar Rift. Plots oC earthquai:e activity shaw lhal NW striking fauIts whlch cut the system transversally are still being activated. The origin of tbis enormoUtl transcurrency may be related to a collision between Protecozoic cratonic masses and oonsequent escape tectonics or, oblique subduction effocts