Article
 

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

Public Deposited

Downloadable Content

Download PDF
https://ir.library.oregonstate.edu/concern/articles/zs25xf04w

Descriptions

Attribute NameValues
Creator
Abstract
  • Bulk mineral assemblages of sediments and igneous basement rocks on the incoming Cocos Plate 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 m³/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 ∼100°C, 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.
  • This is the publisher’s final pdf. The article is copyrighted by American Geophysical Union and published by John Wiley & Sons, Inc. It can be found at: http://agupubs.onlinelibrary.wiley.com/agu/journal/10.1002/%28ISSN%291525-2027/
  • Keywords: Costa Rica margin, diagenesis, CRISP, seismicity
  • Keywords: Costa Rica margin, diagenesis, CRISP, seismicity
Resource Type
DOI
Date Available
Date Issued
Citation
  • Kameda, J., Harris, R. N., Shimizu, M., Ujiie, K., Tsutsumi, A., Ikehara, M., ... & Kimura, G. (2015). Hydrogeological responses to incoming materials at the erosional subduction margin, offshore Osa Peninsula, Costa Rica. Geochemistry, Geophysics, Geosystems, 16(8), 2725-2742. doi:10.1002/2015GC005837
Journal Title
Journal Volume
  • 16
Journal Issue/Number
  • 8
Rights Statement
Publisher
Peer Reviewed
Language
Replaces

Relationships

Parents:

This work has no parents.

Items

Thumbnail Title Date Uploaded Visibility Actions
file details HarrisRobertCEOASHydrogeologicalResponsesIncoming.pdf 2017-10-27 Public Download