Paleomagnetic constraints on the kinematic relationship between the Guerrero terrane (Mexico) and North America since Early Cretaceous time

Abstract

The North American Cordillera has been shaped by a long history of accretion of arcs and other buoyant crustal fragments to the western margin of the North American plate since early Mesozoic time. The southernmost accreted terrane is the Guerrero terrane of southwestern Mexico, a latest Jurassic-Cretaceous volcanic arc built on a Triassic accretionary prism. Interpretations of the origin of the Guerrero terrane vary: Some authors consider it a far-traveled, exotic intra-oceanic island arc, while others view it as the (par)autochthonous, extended North American continental margin. We present new paleomagnetic and U-Pb zircon data from Lower Cretaceous sedimentary rocks of the Guerrero terrane. These data show that the Guerrero terrane has a latitudinal plate-motion history equal to that of the North America plate, both before and after accretion. This confirms paleogeographic models in which the Guerrero arc successions formed on North American crust that rifted away from the Mexican mainland by approximately east-west opening of a back-arc basin above an eastward-dipping subduction zone. Additionally, it renders alternative paleogeographical models in which the Guerrero terrane is considered to be exotic to the North American continent unlikely. The phase of back-arc spreading resulted in the short-lived existence of an additional "Guerrero" tectonic plate between the North American and Farallon plates and, upon closure of the back-arc basin, the growth of the North American continent.

The Dynamic History of 220 Million Years of Subduction Below Mexico: A Correlation Between Slab Geometry and Overriding Plate Deformation Based on Geology, Paleomagnetism, and Seismic Tomography

“…The terrane became temporarily separated from North America as a result of Late Jurassic to Early Cretaceous Arperos backarc basin opening, which was subsequently inverted to close in mid‐Cretaceous time, all within the overriding plate of an eastward dipping subduction zone below North America (Cabral‐Cano et al, ; Centeno‐García, ; Centeno‐García et al, , ; Elias‐Herrera et al, ; Martini et al, ). Boschman et al () recently showed that the paleolatitudinal motion of the Guerrero terrane follows North American plate motion since Early Cretaceous time, confirming the latter hypothesis.…”

“…Arperos lithosphere may have merged with the main Cocos slab anomaly, such that it became indistinguishable from subducted Farallon lithosphere ( G ). Paleomagnetic data had already shown that opening and closure of the back‐arc basin was not associated with significant paleolatitudinal motion (Boschman et al, ) and the absence of an identifiable slab now suggests that also paleolongitudinal motions were limited. This indicates that overriding North American plate margin extension or shortening since Triassic time was probably limited to a few hundreds of kilometers during each event.…”

“…Both arcs are underlain by a basement of Triassic‐Jurassic rocks, in the Guerrero area interpreted as an accretionary prism that formed at the continental margin (Centeno‐García et al, , ; Schmidt et al, ; Talavera‐Mendoza et al, ). In Early Cretaceous time, the arcs terranes separated from the continent and did not receive cratonal sedimentary detritus until after their mid‐Cretaceous collision with North America (Alsleben et al, ; Boschman et al, ; Busby et al, ; Talavera‐Mendoza et al, ).…”

“…Our new paleomagnetic data from the Vizcaíno-Cedros region yield a paleolatitudinal plate motion history equal to that of the North American Plate since Late Triassic time. We follow the argumentation of Boschman et al (2018) on the kinematic relationship between the Guerrero terrane and North America: latitudinal (northward) plate motion relative to the North American continent is expected for an accreted exotic terrane that formed in an intraoceanic setting on one of the oceanic plates of the eastern Panthalassa Ocean (e.g., Farallon, Kula). A latitudinal plate motion history equal to that of the North American Plate, on the other hand, indicates that the "accreted" terrane formed within the (deforming by forearc or backarc spreading and subsequent shortening) upper plate.…”

Paleomagnetism and Geochronology of the Early Cretaceous Dipilto Batholith (NW Nicaragua): Chortís Block Large Rotation With Respect to SW North America

“…Second, the western margin of Mexico was completing a process of extension and westward arc migration (Centeno‐García, ; Ortega‐Flores et al, ), and beginning diachronic compression and closure from north to south of the Arperos back‐arc basin (Martini et al, ). Penecontemporaneously, the convergent system of NW of Mexico (Baja California) was undergoing the Alisitos arc assembly and formation of an accretionary complex, as a result of the Farallon plate subduction below NAM (Alsleben et al, ; Boschman et al, ; Schmidt et al, ). On the other hand, the accretionary complex is absent it the southwestern part of Mexico (i.e., SW of the Guerrero Terrane) and was probably truncated by geodynamics of the Farallon‐Cocos‐NAM plates or the Chortís block (Ferrari et al, ; Schaaf et al, ).…”