The elusive Rivera-Cocos plate boundary: not diffuse
Por:
Alvarez, Roman, Yutsis, Vsevolod
Publicada:
1 ene 2016
Resumen:
Inland and offshore gravimetric determinations in the Southern Colima
rift in western Mexico allowed for the construction of a Bouguer anomaly
map of the area. Four submarine canyons of tectonic relevance are
located in the offshore area. Gravimetric models of the oceanic
subducting slab were calculated from the residual Bouguer anomaly along
six trench-parallel lines and three trench-perpendicular lines including
the area of the canyons. The former lines show considerable distortion
of the slab that we attribute to compression, while the latter show
distinct dipping angles of the oceanic slab at distances of around 75 km
from the trench: the westernmost line shows a dip angle of 558 between
depths of 20 and 70 km, while the easternmost shows a dip angle of 328
at depths between 18 and 50 km. We submit that the former represents a
section of the subducting Rivera plate, and the latter represents a
section of the Cocos plate. Extracting coordinates of representative
points on the surface of the nine slab models allowed for a
reconstruction of the slab surface: the transition from the Rivera to
the Cocos plate is marked by topographic gradients in the modelled slab
surface suggesting the trajectory of the boundary between the plates. We
propose a tectonic model that includes a transpression zone involving
the marine platform and the Southern Colima rift and a transtension zone
in the Northern Colima rift: the Colima Volcanic Complex is located in
the transition zone between them.
Filiaciones:
Univ Nacl Autonoma Mexico, Inst Invest Matemat Aplicadas & Sistemas, Ciudad Univ, Mexico City 04510, DF, Mexico
Inst Potosino Invest Cient & Tecnol, Camino Presa San Jose 2055,Lomas 4a Secc, San Luis Potosi 78216, SLP, Mexico
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