Costa Rica Seismogenesis Project, Program A Stage 1 (CRISP-A1)

Vannucchi, P.; Ujiie, Kohtaro; Stroncik, Nicole A.; Malinverno, Alberto

doi:10.2204/iodp.proc.334.2012

Cited by 25 publications

(35 citation statements)

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“…The chalk layer was also cored and sampled at nearby Site 1253. More recent drilling has been initiated as the Costa Rica Seismogenesis Project (CRISP) during IODP Expeditions 334 (Vannucchi et al, 2012) and 344 (Harris et al, 2013b) offshore Osa Peninsula to the southeast. Two input sites have been drilled in this location: Site U1381 during Expedition 334, and Site U1414 during Expedition 344, both located ~5 km from the deformation front.…”

Section: Middle America Trench Costa Rica Geologic Settingmentioning

confidence: 99%

Lithologic control of frictional strength variations in subduction zone sediment inputs

et al. 2018

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At convergent margins, marine sediments deposited seaward of the subduction zone forearc on the incoming plate (the "subduction inputs") represent the initial condition for geomechanical processes during subduction. The frictional strength of these sediments is a key parameter governing deformation during subduction, which is controlled to first order by lithologic composition. We combine here the results of laboratory friction experiments and quantification of mineral assemblage for scientific drilling samples recovered from three particularly well-studied subduction zones: the Nankai Trough (southwestern Japan), the Japan Trench (northeastern Japan), and Costa Rica. In the Japan Trench, frictionally weak smectite-rich pelagic clay contrasts sharply with stronger, more siliceous hemipelagic material. This strength contrast dictates the stratigraphic position of initial plate boundary formation and influences slip behavior of the shallow megathrust. In the Costa Rica subduction zone, relatively weak clay-rich hemipelagic sediment overlies frictionally strong pelagic nannofossil oozes and chalks, which could be a factor for the development of features such as a small amount of offscraping near the toe and subduction erosion where ooze or chalk dominates. In the Nankai Trough, however, a wide range of frictional strength values is observed that does not correlate with clay mineral content. In this case, mechanical behavior at Nankai is likely influenced by other factors related to diagenesis or fluid overpressuring.

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Section: Middle America Trench Costa Rica Geologic Settingmentioning

confidence: 99%

Lithologic control of frictional strength variations in subduction zone sediment inputs

et al. 2018

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“…IODP Expedition 334 cored four sites along the CRISP transect [Vannucchi et al, 2012]. Three of these sites are located on the trench slope of the forearc prism and one site (U1381A) on the Cocos plate seaward of Geochemistry, Geophysics, Geosystems 10.1002/2015GC005837 the trench (Figure 1a) [Vannucchi et al, 2012]. Drilling at U1381A (8825.7150 0 N, 848 9.4690 0 W) recovered approximately 100 m of sedimentary cover and 70 m of oceanic basement.…”

Section: Geological Background and Iodp Site U1381amentioning

confidence: 99%

“…The Costa Rica Seismogenesis Project (CRISP) offshore the Osa Peninsula, was undertaken to better understand erosional convergent margins and the role of fluids [Vannucchi et al, 2012]. In this study, we use X-ray diffraction (XRD) to quantify the mineral composition of material recovered at Site U1381, the sedimentary Special Section:…”

Section: Introductionmentioning

confidence: 99%

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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“…The MSR offshore Osa is distinct from the unconformity developed above the mafic units offshore Nicoya Peninsula to the north [e.g., Kimura et al, 1997;Vannucchi et al, 2001], and the variability along the trench could possibly be due in part to the effect of Cocos Ridge subduction to the south. This fractured margin is also an active region of vigorous fluid flow focused along faults and permeable zones inferred from geophysical surveys [e.g., Ranero et al, 2008;Sahling et al, 2008;Kluesner et al, 2013], pore water geochemistry studies [e.g., Vannucchi et al, 2012;Harris et al, 2013bHarris et al, , 2013c, and the zeolite assemblages in this study. This paper has tested and revealed the impact of pore-filling minerals (e.g., zeolite) resulting from this fluid flow on the sediment consolidation and porosity difference across the MSR.…”

Section: Integration Of Resultsmentioning

confidence: 82%

Normal faulting and mass movement during ridge subduction inferred from porosity transition and zeolitization in the Costa Rica subduction zone

Hamahashi

Screaton

Tanikawa

et al. 2017

Geochem Geophys Geosyst

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Subduction of the buoyant Cocos Ridge offshore the Osa Peninsula, Costa Rica substantially affects the upper plate structure through a variety of processes, including outer forearc uplift, erosion, and focused fluid flow. To investigate the nature of a major seismic reflector (MSR) developed between slope sediments (late Pliocene‐late Pleistocene silty clay) and underlying higher velocity upper plate materials (late Pliocene‐early Pleistocene clayey siltstone), we infer possible mechanisms of sediment removal by examining the consolidation state, microstructure, and zeolite assemblages of sediments recovered from Integrated Ocean Drilling Program Expedition 344 Site U1380. Formation of Ca‐type zeolites, laumontite and heulandite, inferred to form in the presence of Ca‐rich fluids, has caused porosity reduction. We adjust measured porosity values for these pore‐filling zeolites and evaluated the new porosity profile to estimate how much material was removed at the MSR. Based on the composite porosity‐depth curve, we infer the past burial depth of the sediments directly below the MSR. The corrected and uncorrected porosity‐depth curves yield values of 800 ± 70 m and 900 ± 70 m, respectively. We argue that deposition and removal of this entire estimated thickness in 0.49 Ma would require unrealistically large sedimentation rates and suggest that normal faulting at the MSR must contribute. The porosity offset could be explained with maximum 250 ± 70 m of normal fault throw, or 350 ± 70 m if the porosity were not corrected. The porosity correction significantly reduces the amount of sediment removal needed for the combination of mass movement and normal faulting that characterize the slope in this margin.

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Costa Rica Seismogenesis Project, Program A Stage 1 (CRISP-A1)

Cited by 25 publications

References 0 publications

Lithologic control of frictional strength variations in subduction zone sediment inputs

Lithologic control of frictional strength variations in subduction zone sediment inputs

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

Normal faulting and mass movement during ridge subduction inferred from porosity transition and zeolitization in the Costa Rica subduction zone

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