Tectonic significance of paleomagnetic data from northern Venezuela

Abstract

A paleomagnetic study, mostly of basic intrusive rocks of Cretaceous and Tertiary age from northern Venezuela, includes 153 samples from 31 sites, of which only 6 sites failed to give consistent results. Fifteen sites within the Caribbean Mountains have easterly declinations with shallow, mixed positive and negative inclinations. These anomalous vectors are interpreted to be the result of tectonic rotation about vertical axes rather than to reflect anomalous magnetic field orientations associated with a polarity transition. Although these sample sites are within igneous intrusive bodies with no control on the original attitude during acquisition of the natural remanent magnetization, the relative conformity of data from numerous separate intrusions requires an average 90 ø megatec-

Clockwise rotation of the Santa Marta massif and simultaneous Paleogene to Neogene deformation of the Plato-San Jorge and Cesar-Ranchería basins

“…RR2, Bayona et al, this issue) but ignored here due poor structural control. These new paleomagnetic data lend further support to the overall vertical-axis rotation of the Santa Marta massif, but with moderate values, instead of intermediate to large values found in the southern Caribbean region (Hargraves and Shagam, 1969;MacDonald and Opdyke, 1984;Skerlec and Hargraves, 1980;Gose et al, 2003). The discrepancy in the magnitude of rotation needs to be investigated further.…”

“…In the previous sections, we have presented evidence for: (1) incipient early Eocene mild deformation related to thrust sheet Feininger (1970), Schubert and Sifontes (1970), Tschanz et al (1974), Skerlec andHargraves (1980), andSchamel (1991) . Fig.…”

“…8) region suggest intermediate (50°) to large (90°) vertical-axis rotation values (Hargraves and Shagam, 1969;MacDonald and Opdyke, 1972;Skerlec and Hargraves, 1980;Gose et al, 2003). Counterclockwise vertical-axis rotations have also been also reported in the Perijá range (Maze and Hargraves, 1984), but the dispersion value reported (a-95 of 64) of these analyses is too large to be considered a reliable data point.…”

Plate-kinematics and crustal dynamics of circum-Caribbean arc-continent interactions: Tectonic controls on basin development in Proto-Caribbean margins

“…Joyce and Aronson, 1989;Draper and Nagle, 1991;Krebs et al, 1999Krebs et al, , 2003Perfi t and McCulloch, 1982;Gonçalves et al, 2000;Catlos and Sorensen, 2003 Duarte Lapierre et al, 1999;Lewis, 1989, 1991 Amina-Maimón late Aptian-Albian plutonism and volcanism, also of "primitive island arc" character. Snoke et al, 1990;Speed and Smith-Horowitz, 1998 La Rinconada Smith et al, 1999;Hebeda et al, 1984;Skerlec and Hargraves, 1980;Kohn et al, 1984 Continued on July 1, 2015 specialpapers.gsapubs.org Downloaded from spe394-01 page 19 history into the late Cenozoic Blueschist metamorphism probably occurred at westdipping subduction zone, as also inferred for Margarita and Villa de Cura HP-LT rocks. Relationships of HP-LT rocks to greenschist-grade "passive margin" protoliths are not clear, nor is the original depositional location of these "passive margin" rocks: are they paraautochthonous parts of the central Venezuelan margin or do they derive from farther west?…”

Tectonics, basin subsidence mechanisms, and paleogeography of the Caribbean-South American plate boundary zone

“…3) do not show large, active rotations of forearc areas in the collisional zone between the Caribbean arc and northern South America. However, paleomagnetic data from across the collisional zone does reveal that large, vertical-axis rotations up to 90 degrees in a clockwise sense have occurred since Cretaceous (Skerlec and Hargraves, 1980), providing some support for the Wallace et al (2005Wallace et al ( , 2009) rotation model.…”