O Lineamento Sismo-Tectônico De Cabo Frio

Abstract

o L1 NEA MENTO SISMO-TECTONICO DE CABO FR IO GEO RG ROB ERT SA DOWS KI' e CO RIO LANO DE M. D IAS NETO' ABS TRACT The Cabo Frio lineament was defined as a co ntinental expression of a ridge offset Fo rmed-du ri ng the separatio n of the co ntinents. It coi ncides with a line o f seismic act ivit y, with several alkalincs of Seno nian and Paleocene age, and with disruptive structures. Historical and recent ear thquakes were located by intensity and instrumental data. The alkaline lineament co incides "vith a Scno mian-Paleocenc plate trajectory obtained thro ugh back rotation of the co ntinents alo ng the pole s defined by Ladd (1975). Geoc hrono logica lly th e a lkalines show a trend of lo wer ages to wards the cast. The se features indica te a possible existence of a ho t spo t type mechanism in this area associated with the major mesozo ic thermal Pont a Grcss ac-Mossamedes swell.

Hot spot volcanic tracks and their implications for south American plate motion, Campos basin (Rio de Janeiro state), Brazil

“…In this respect, their view concurs with those of Herz (1977), Cordani and Teixeira (1979), Sadowski and Dias Netto (1981), Fletcher and Litherland (1981), Fodor et al (1983Fodor et al ( /1984, and Thompson et al (1998). Important supporting evidence for this view is the decrease in the K/ Ar radiometric ages from west to east (Fig.…”

Influence of pre-salt alignments in post-Aptian magmatism in the Cabo Frio High and its surroundings, Santos and Campos basins, SE Brazil: An example of non-plume-related magmatism

“…Almeida (1991) suggests that both the Brazilian volcanic islands and the seamounts of the Abrolhos volcanic complex/Vitó ria-Trindade fracture zone and the magmatic alignment of Poc ßos de Caldas (82 Ma, Ar/Ar)-Cabo Frio (53 Ma, Ar/Ar) are located over extensive fracture zones, where the magma ascended during reactivations. However, several authors attribute such alignments to mantle plumes and hotspots (e.g., Sadowski and Dias Netto, 1981;Herz, 1987;Thompson et al, 1998;Szatmari et al, 2000;Cobbold et al, 2001;Assumpc ßão et al, 2004;Thomaz Filho et al, 2005). In carefully analyzing the strike-slip faults inferred by Cobbold et al (2001), we conclude that the igneous bodies are placed at the intersections of the SE-NW-trending strike-slip faults with the SW-NE-trending normal ones.…”

Geochronology (Ar/Ar and K–Ar) of the South Atlantic post-break-up magmatism

“…7) occurs as plugs, stocks, dykes and sills that present several trends, from a general ENE direction for the dykes to NW-SE and east -west lineaments, as evidenced by the geological and geophysical datasets in the continental crust adjacent to the Santos and Campos basins (e.g. Sadowski & Dias Neto 1981). These alkaline complexes most probably represent the roots of extinct Cretaceous volcanoes (Motoki et al 2008d).…”

“…In the State of Rio de Janeiro and its adjacent areas, along the longitude 428W-ESE lineament, there are a dozen felsic alkaline intrusive rock bodies forming a WNW-ESE lineament called the Poços de Caldas -Cabo Frio alkaline rock alignment (Sadowski & Dias Neto 1981;Thomáz-Filho & Rodrigues 1999;Riccomini et al 2004). This lineament includes several intrusions, such as Itatiaia (Brotzu et al 1979), Morro Redondo (Brotzu et al 1989), Tinguá (Derby 1897), Mendanha (Motoki et al 2007c), Itaúna (Motoki et al 2008d), Tanguá, Rio Bonito, Soarinho , Morro dos Gatos, Morro de São João (Brotzu et al 2008;Mota et al 2009) and Cabo Frio Island Motoki et al 2008a).…”