Seamount, ridge, and transform subduction in southern Central America

Abstract

Understanding the factors that control subduction zone processes is a first-order goal in the study of convergent margins. In southern Central America, a growing body of research reveals strong links between the character of the subducting slab and the mechanics of important processes that include subduction erosion, fluid flow, deformation, and seismogenesis. In this paper, I evaluate the role that seamount, ridge, and transform subduction have in the development of upper plate deformation and volcanism by summarizing previous work across a >500 km long region of Central America where each of these three scenarios are present along strike. The data show that the subduction of short-wavelength bathymetry (e.g., seamounts and faults on the seafloor) produces short-wavelength deformation that persists for relatively short timescales (10 4 -10 5 years), whereas the subduction of longer-wavelength bathymetry (e.g., the aseismic Cocos Ridge) results in longer-wavelength deformation that endures over a longer time scale (10 6 years). The timing and distribution of upper plate deformation are consistent with subhorizontal Cocos Ridge subduction driving upper plate deformation, and the increased crustal thickness (>20 km) of the subducting Cocos Ridge is likely one of the most important factors in the production of upper plate contraction and crustal thickening. The data illustrate a fundamental connection between lower plate properties and upper plate deformation and highlight the profound influence that bathymetry and crustal thickness have in the localization and kinematics of upper plate strain and volcanism in Middle America.

Plio‐Quaternary Outer Forearc Deformation and Mass Balance of the Southern Costa Rica Convergent Margin

“…Geologic map of Costa Rica and western Panama modified from Morell () and references therein. Bathymetric data and bathymetric scale same as Figure .…”

“…(a) Geologic map of the Fila Costeña Thrust Belt, showing ∼75 new bedding orientation data combined with previously published data from Fisher et al (), Sitchler et al (), Morell et al (), Sak et al (), Morell et al (), and Morell (). The décollement beneath the Fila Costeña steps up section in the northwestern portion of the thrust belt and therefore does not expose the Brito Fm.…”

“…The décollement of the Fila Costeña is hypothesized to extend downdip to root beneath the uplifted Cordillera de Talamanca volcanic arc to form an orogen‐scale pop‐up structure together with back thrusts in the Limón backarc basin (Figures and ; Brandes et al, ; Fisher et al, ; Morell, , ). Evidence for uplift of the Talamanca compared to adjacent arc segments has long been suggested because of their anomalously high elevations (de Boer et al, ; Gräfe et al, ).…”

Slip Inversion Along Inner Fore‐Arc Faults, Eastern Tohoku, Japan

“…The fore‐arc regions of subduction zones, like that of Northeast Honshu, Japan, are constructed and deformed over multiphase histories and evolve in response to changes in the subducting bathymetry (e.g., Audin et al, ; Bangs et al, ; Fisher et al, ; Gardner et al, ; Hampel, ; Kington & Tobin, ; Morell et al, ; Regard et al, ; Wang & Bilek, ), convergence rate and obliquity (e.g., Allmendinger & González, ; Morell, ; Regalla, Fisher, et al, ), mechanical properties of the megathrust (e.g., Allmendinger & González, ; Buiterr et al, ; Hassani et al, ; Saffer & Tobin, ), and variations in slab geometry (e.g., Capitanio et al, ; Capitanio et al, ; Royden & Husson, ). Variations in stress state during such deformation events can lead to the development of networks of upper plate faults that can act as structural weaknesses available to be reactivated in response to subsequent changes in boundary conditions at the plate interface.…”

Dots-and-Lines Approach to Subduction Volcanism and Tectonics

“…み断面の描像が示されている (Mibe et al, 1999;Iwamori, 2004Iwamori, , 2007Hasegawa et al, 2009;Kogiso et al, 2009 et al, 1999;Manea et al, 2014;Morell, 2016 Gutscher et al, 1999;Manea et al, 2014;Morell, 2016) . In Kamchatka (c) , the Klyuchevskoy volcanic group, having huge volcanoes, is directly on the subduction trend of the Meiji-Emperor Seamounts (Scholl, 2007) .…”