Tectonic erosion and consequent collapse of the Pacific margin of Costa Rica: Combined implications from ODP Leg 170, seismic offshore data, and regional geology of the Nicoya Peninsula

Vannucchi, Paola; Scholl, David W.; Meschede, Martin; McDougall-Reid, Kristin

doi:10.1029/2000tc001223

Cited by 138 publications

(179 citation statements)

References 45 publications

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“…This diversity is best explained through the severe damages caused by the ridge to the margin, as suggested by the disrupted topography . Moving south from Nicoya Peninsula, where the subducting plate is smoother and the trench retreat has been estimated to be $50 km since 16 Ma [Vannucchi et al, 2001], to Osa Peninsula the slope has retreated up to 20 km (Figure 1a). In Osa, upper plate thinning by subduction erosion is counteracted by horizontal shortening and internal deformation of the wedge to produce uplift.…”

Section: From Tectonic Accretion To Tectonic Erosion: Discussionmentioning

confidence: 99%

“…Ridge subduction caused contrasting consequences as uplift inboard of the Cocos Ridge and subsidence recorded offshore Nicoya Peninsula, $300 km to the northwest [Vannucchi et al, 2001], both in a subduction erosion regime. This diversity is best explained through the severe damages caused by the ridge to the margin, as suggested by the disrupted topography .…”

Section: From Tectonic Accretion To Tectonic Erosion: Discussionmentioning

confidence: 99%

“…The 60 -25 Ma Quepos and Osa terrains, in fact, are interpreted to reflect rocks accreted from subducted edifices generated by the Galapagos hot spot [Hauff et al, 1997[Hauff et al, , 2000 (Figures 1a and 2). Crucially there is no evidence that the Costa Rican forearc is composed of an accretionary complex of tectonized sediments offscraped from the currently subducting plate Vannucchi et al, 2001;Fisher et al, 2004]. Plate reconstructions indicate that the Cocos-Nazca-Caribbean triple junction migrates to the southeast at a rate of $50 km/Myr, implying that the Nazca plate was subducting beneath southeast Costa Rica in the late Neogene [Gardner et al, 1992].…”

Section: Tectonic Setting and Previous Studymentioning

confidence: 99%

“…This subduction front extends for about 1100 km from Mexico along Guatemala, El Salvador and Nicaragua to Costa Rica. Deep sea drilling [Vannucchi et al, 2001 and geophysical exploration of the margin Ranero and von Huene, 2000] indicate subduction erosion as the main process shaping the outer fore arc.…”

Section: Tectonic Setting and Previous Studymentioning

confidence: 99%

“…Unfortunately active processes taking place in the outer part of the forearc are submarine and not easily accessible, while exposed fossil systems are rare, because erosive processes inherently do not lead to material preservation. However, on Osa Peninsula (Figure 1a), along the erosive plate boundary of the Middle America Trench (MAT) in Costa Rica Vannucchi et al, 2001Vannucchi et al, , 2004, the outermost fore arc is exposed, providing a window into the tectonic evolution of the area. The greatest uplift and unroofing is occurring in the region inboard of prominent bathymetric highs on the subducting plate, most notably the Cocos Ridge [Gardner et al, 1992;Fisher et al, 1998] (Figure 1a).…”

Section: Introductionmentioning

confidence: 99%

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From seamount accretion to tectonic erosion: Formation of Osa Mélange and the effects of Cocos Ridge subduction in southern Costa Rica

Vannucchi¹,

et al. 2006

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The Costa Rica portion of the Middle America Trench (MAT) is characterized by active tectonic erosion, a process that causes the removal of material from the base of the upper plate as the plate boundary migrates upward. Offshore studies demonstrate accelerated subduction erosion starting at the Miocene‐Pliocene boundary, as the result of subduction of thickened Galapagos related crust, as presently represented by the Cocos Ridge. The subduction of the Cocos Ridge also caused uplift and exposure of the outer forearc on the Osa Peninsula, which offers a window to explore the tectonic evolution of the area. The rocks outcropping on Osa Peninsula are a middle Eocene–middle Miocene mélange dominated by basalt, chert, and limestone resulting from accretion of seamounts. The accretion‐dominated period of the MAT evolution ended at the Miocene‐Pliocene boundary, when thickened crust, a paleo‐Cocos Ridge, produced at the Galapagos hot spot arrived at the trench. The thick crust caused uplift and severe tectonic erosion of the accretionary edifice allowing exhumation of the Osa Mélange. The change from accretion to erosion caused the outer forearc to be offset along subvertical faults that define small (kilometer to tens of kilometers size) blocks that are going through differential vertical movements in response to the morphology of the subducting ridge. Subduction accretion and erosion are two processes that can alternate in time and space or coexist along the same margin, so that mass removal can develop on a previously growing margin and completely remove an accretionary prism.

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Section: From Tectonic Accretion To Tectonic Erosion: Discussionmentioning

confidence: 99%

Section: From Tectonic Accretion To Tectonic Erosion: Discussionmentioning

confidence: 99%

Section: Tectonic Setting and Previous Studymentioning

confidence: 99%

Section: Tectonic Setting and Previous Studymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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From seamount accretion to tectonic erosion: Formation of Osa Mélange and the effects of Cocos Ridge subduction in southern Costa Rica

Vannucchi¹,

et al. 2006

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The impact of splay faults on fluid flow, solute transport, and pore pressure distribution in subduction zones: A case study offshore the Nicoya Peninsula, Costa Rica

Lauer

Saffer

2015

Geochem Geophys Geosyst

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Observations of seafloor seeps on the continental slope of many subduction zones illustrate that splay faults represent a primary hydraulic connection to the plate boundary at depth, carry deeply sourced fluids to the seafloor, and are in some cases associated with mud volcanoes. However, the role of these structures in forearc hydrogeology remains poorly quantified. We use a 2-D numerical model that simulates coupled fluid flow and solute transport driven by fluid sources from tectonically driven compaction and smectite transformation to investigate the effects of permeable splay faults on solute transport and pore pressure distribution. We focus on the Nicoya margin of Costa Rica as a case study, where previous modeling and field studies constrain flow rates, thermal structure, and margin geology. In our simulations, splay faults accommodate up to 33% of the total dewatering flux, primarily along faults that outcrop within 25 km of the trench. The distribution and fate of dehydration-derived fluids is strongly dependent on thermal structure, which determines the locus of smectite transformation. In simulations of a cold end-member margin, smectite transformation initiates 30 km from the trench, and 64% of the dehydration-derived fluids are intercepted by splay faults and carried to the middle and upper slope, rather than exiting at the trench. For a warm end-member, smectite transformation initiates 7 km from the trench, and the associated fluids are primarily transmitted to the trench via the decollement (50%), and faults intercept only 21% of these fluids. For a wide range of splay fault permeabilities, simulated fluid pressures are near lithostatic where the faults intersect overlying slope sediments, providing a viable mechanism for the formation of mud volcanoes.

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Hydrogeological responses to incoming materials at the erosional subduction margin, offshore Osa Peninsula, Costa Rica

Kameda

Harris

Shimizu

et al. 2015

Geochem Geophys Geosyst

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Bulk mineral assemblages of sediments and igneous basement rocks on the incoming CocosPlate at the Costa Rica subduction zone are examined by X-ray diffraction analyses on core samples. These samples are from Integrated Ocean Drilling Program Expedition 334 reference Site U1381, 5 km seaward of the trench. Drilling recovered approximately 100 m of sediment and 70 m of igneous oceanic basement. The sediment includes two lithologic units: hemipelagic clayey mud and siliceous to calcareous pelagic ooze. The hemipelagic unit is composed of clay minerals (50 wt.%), quartz (5 wt.%), plagioclase (5 wt.%), calcite (15 wt.%) and 30 wt.% of amorphous materials, while the pelagic unit is mostly made up of biogenic amorphous silica (50 wt.%) and calcite (50 wt.%). The igneous basement rock consists of plagioclase (50-60 wt.%), clinopyroxene (>25 wt.%), and saponite (15-40 wt.%). Saponite is more abundant in pillow basalt than in the massive section, reflecting the variable intensity of alteration. We estimate the total water influx of the sedimentary package is 6.9 m 3 /yr per m of trench length. Fluid expulsion models indicate that sediment compaction during shallow subduction causes the release of pore water while peak mineral dehydration occurs at temperatures of approximately 1008C, 40-30 km landward of the trench. This region is landward of the observed updip extent of seismicity. We posit that in this region the presence of subducting bathymetric relief capped by velocity weakening nannofossil chalk is more important in influencing the updip extent of seismicity than the thermal regime.

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Tectonic erosion and consequent collapse of the Pacific margin of Costa Rica: Combined implications from ODP Leg 170, seismic offshore data, and regional geology of the Nicoya Peninsula

Cited by 138 publications

References 45 publications

From seamount accretion to tectonic erosion: Formation of Osa Mélange and the effects of Cocos Ridge subduction in southern Costa Rica

From seamount accretion to tectonic erosion: Formation of Osa Mélange and the effects of Cocos Ridge subduction in southern Costa Rica

The impact of splay faults on fluid flow, solute transport, and pore pressure distribution in subduction zones: A case study offshore the Nicoya Peninsula, Costa Rica

Hydrogeological responses to incoming materials at the erosional subduction margin, offshore Osa Peninsula, Costa Rica

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