Rock uplift and exhumation of continental margins by the collision, accretion, and subduction of buoyant and topographically prominent oceanic crust

Abstract

Understanding the causes of rock and surface uplift is important because they control the location of mountain building, depocenters, and drainage characteristics and can influence climate. Here we combine previous thermochronological data with field observations to determine the amount of exhumation, rock, and surface uplift that occurs in the upper plate of Central and South American subduction zones during the collision, accretion, and subduction of oceanic plateaus and aseismic ridges. The collision of buoyant and topographically prominent oceanic plateaus and ridges can drive at least 5 km of rock uplift within 2 Ma. Uplift appears to be an immediate response to collision and is generally independent of the slab dip. The amount of rock uplift is controlled mainly by excess topography associated with the ridge (ultimately linked to buoyancy) and erosion, while it is also influenced by the strength of the subduction interface related to the presence of volcanic asperities and overpressured sediments in the subduction channel. The quantity of exhumation is strongly dependant on climate-induced erosion and the lifespan over which the topography is uplifted and supported. Sediment draining into the trench may leave the elevated ridge axis sediment starved, increasing the shear stresses at the ridge subduction interface, leading to positive feedback between ridge subduction, rock uplift, and exhumation. Trench-parallel variations in exhumation have a direct impact on exploration paradigms for porphyry-related metalliferous deposits, and it is likely that porphyry systems are completely eroded by the impingement of plateaus and aseismic ridges within temperate and tropical climates.

Deformation of erosive and accretive forearcs during subduction of migrating and non‐migrating aseismic ridges: Results from 3‐D finite element models and application to the Central American, Peruvian, and Ryukyu margins

“…Among them are the Osa und Burica Peninsulas, which are located about 20–30 km away from the Central American Trench, a thrust belt called Fila Costeña and—separated from the Fila Costeña by a valley—the Talamanca Range, which shows the largest width and highest peaks inboard of the Cocos Ridge (Figure a). The Burica Peninsula coincides with the prolongation of the southeastern edge of the Cocos Ridge as well as with the northern end of the Panama Fracture Zone [e.g., Gardner et al ., ; Morell et al ., ; Spikings and Simpson , ]. A wealth of data exists on the uplift history of the peninsulas and the exhumation history of the Talamanca Range, which many authors attribute at least partly to the subduction of the Cocos Ridge [e.g., Corrigan et al ., ; Sitchler et al ., ; Morell et al ., ; Gardner et al ., ], although the onset of ridge subduction is still under debate.…”

“…Also not considered are erosion and sedimentation of the forearc wedge, with the consequence that our models cannot provide constraints, for example, on rates of rock exhumation above subducting ridges [cf. Wipf et al ., ; Spikings and Simpson , ].…”

“…At deeper levels, ridges and subducted plateaus may contribute to the formation of flat slabs [e.g., Gutscher et al ., ; van Hunen et al ., ; Espurt et al ., ] although the link between ridge subduction and slab flattening is not yet confirmed and other factors like slab rollback and a trenchward advance of a thick overriding plate may also play a role [ van Hunen et al ., ; Manea and Gurnis , ; Manea et al ., ]. From their abundance in the present‐day oceans, it can be assumed that a number of bathymetric highs have also been subducted in the past and probably influenced the topographic and tectonic evolution of the affected margin [e.g., Gutscher et al ., ; Rosenbaum et al ., ; Spikings and Simpson , ].…”

“…Among these effects are the indentation of the frontal part of the upper plate accompanied by a landward shift of the trench [e.g., Bouysse and Westercamp , ; Schnürle et al ., ; Lallemand et al ., ] and uplift of the forearc, which may lead to formation of marine terraces at the coast [e.g., Corrigan et al ., ; Gardner et al ., , ; Hsu , ; Macharé and Ortlieb , ; Saillard et al ., ]. Farther landward, ridge subduction may induce uplift and shortening [e.g., Fisher et al ., ; Sitchler et al ., ; Espurt et al ., ; Regard et al ., ] and enhance the exhumation of rocks [ Wipf et al ., ; Spikings and Simpson , ]. At deeper levels, ridges and subducted plateaus may contribute to the formation of flat slabs [e.g., Gutscher et al ., ; van Hunen et al ., ; Espurt et al ., ] although the link between ridge subduction and slab flattening is not yet confirmed and other factors like slab rollback and a trenchward advance of a thick overriding plate may also play a role [ van Hunen et al ., ; Manea and Gurnis , ; Manea et al ., ].…”

Rapid vertical motions and formation of volcanic arc gaps: Plateau collision recorded in the forearc geological evolution (Costa Rica margin)

“…The impingement of prominent bathymetric features (seamounts, ridges, plateaus) is common in modern convergent margins ( Figure 1) and may cause flattening of the slab dip angle, tectonic erosion/accretion, gaps in arc volcanism and kilometric uplift in the overriding plate (Chuang, Bostock, Wech, & Plourde, 2017;Cloos, 1993;McCann & Habermann, 1989;McGeary, Nur, & Benavraham, 1985;Rosenbaum & Mo, 2011;Spikings & Simpson, 2014). Although the effects of colliding bathymetric relief may depend on the amount of sediment, strength of the overriding plate, convergence velocity and size/orientation of the feature, it appears that the response of forearc areas is similar for oceanic and continental margins (Draut & Clift, 2013;Geist, Fisher, & Scholl, 1993;Trehu, Blakely, & Williams, 2012).…”