Implications of paleomagnetic data on the collision related bending of island arcs

Abstract

Paleomagnetic studies from

Collisional model for rapid fore‐arc block rotations, arc curvature, and episodic back‐arc rifting in subduction settings

“…Wallace et al [2005] suggested that the rapid fore-arc rotations are produced by a torque induced by the along-strike change from subduction to collision and that the collision acts as a ''pinning point'' [Mann et al, 2002] for the rotating fore-arc block relative to the lower plate ( Figure 3). The quantitative GPS-based results of Wallace et al [2005] provide further support for McCabe's [1984] concept that back-arc opening can be influenced by collision-induced block rotation.…”

“…[6] In this paper, we further document the compelling spatial and temporal relationship between transition from subduction to collision, plate boundary curvature, rapid tectonic rotations, and the occurrence of back-arc rifting [McCabe, 1984;Wallace et al, 2005;Martin, 2007]. Using our compilation from 23 active and ancient plate margins (detailed in Appendix A, Table 1, and section 4), we demonstrate that most active and many ancient back-arc rifts and curved plate margins are (or were previously) associated with rapid fore-arc rotation and nearby collisions.…”

“…McCabe [1984] pointed out that bending and rotation of subduction plate boundaries often occurs in the absence of back-arc rifting. These observations of active Pacific arc systems led McCabe [1984] to propose that the rotation and bending are triggered at crustal levels by the collision itself, and that the associated large-scale tectonic rotations provide a tectonic mechanism to initiate back-arc rifting (Figure 2b). …”

“…[3] McCabe [1984] advanced the understanding of the spatial relationship between collision in subduction settings and strongly curved plate boundaries by documenting that large paleomagnetic rotations are associated with arc curvature and buoyant indentor collision, and that strongly curved subduction margins are commonly associated with large-scale rigid body rotation of fore-arc microplates within the convergent plate boundary zone. McCabe [1984] pointed out that bending and rotation of subduction plate boundaries often occurs in the absence of back-arc rifting.…”

“…[2] Earth scientists have puzzled for decades over the tectonic origin of strongly curved subduction and collision boundaries including those found in the Alpine-Himalayan orogenic belt, and island arc systems of the southwestern Pacific, Caribbean Sea, Mediterranean Sea and Scotia Sea [e.g., Carey, 1955;Frank, 1968;Vogt et al, 1976;McCabe, 1984;Hsui and Youngquist, 1985] (Figure 1). Carey [1955] and Marshak [1988] postulated that buoyant indentors on the subducting plate play an important role in producing strongly curving trends mapped in older orogenic belts like the Alps and Appalachians.…”