Along-strike structure of the Costa Rican convergent margin from seismic a refraction/reflection survey : evidence for underplating beneath the inner forearc
St. Clair, James
Holbrook, W. Steven
Van Avendonk, Harm J. A.
MetadataShow full item record
The convergent margin offshore Costa Rica shows evidence of subsidence due to subduction erosion along the outer forearc and relatively high rates of uplift (∼3–6 mm/yr) along the coast. Recently erupted arc lavas exhibit a low 10Be signal, suggesting that although nearly the entire package of incoming sediments enters the subduction zone, very little of that material is carried directly with the downgoing Cocos plate to the magma generating depths of the mantle wedge. One mechanism that would explain both the low 10Be and the coastal uplift is the underplating of sediments, tectonically eroded material, and seamounts beneath the inner forearc. We present results of a 320 km long, trench-parallel seismic reflection and refraction study of the Costa Rican forearc. The primary observations are (1) margin perpendicular faulting of the basement, (2) thickening of the Cocos plate to the northwest, and (3) two weak bands of reflections in the multichannel seismic (MCS) reflection image with travel times similar to the top of the subducting Cocos plate. The modeled depths to these reflections are consistent with an ∼40 km long, 1–3 km thick region of underplated material ∼15 km beneath some of the highest observed coastal uplift rates in Costa Rica.
Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 17 (2016): 501–520, doi:10.1002/2015GC006029.
Suggested CitationGeochemistry, Geophysics, Geosystems 17 (2016): 501–520
Showing items related by title, author, creator and subject.
Helium, inorganic and organic carbon isotopes of fluids and gases across the Costa Rica convergent margin Barry, Peter H.; Nakagawa, Mayuko; Giovannelli, Donato; de Moor, J. Maarten; Schrenk, Matthew O.; Seltzer, Alan M.; Manini, Elena; Fattorini, Daniele; di Carlo, Marta; Regoli, Francesco; Fullerton, Katherine; Lloyd, Karen G. (Nature Research, 2019-11-25)In 2017, fluid and gas samples were collected across the Costa Rican Arc. He and Ne isotopes, C isotopes as well as total organic and inorganic carbon concentrations were measured. The samples (n = 24) from 2017 are ...
Lizarralde, Daniel (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1997-05)Many of the most important processes that create and modify continental crust occur at continental margins, but recently has the scientific community acquired the necessary intrumentation to image crustal structure across ...
The intertropical convergence zone modulates intense hurricane strikes on the western North Atlantic margin van Hengstum, Peter J.; Donnelly, Jeffrey P.; Fall, Patricia L.; Toomey, Michael R.; Albury, Nancy A.; Kakuk, Brian (Nature Publishing Group, 2016-02-24)Most Atlantic hurricanes form in the Main Development Region between 9°N to 20°N along the northern edge of the Intertropical Convergence Zone (ITCZ). Previous research has suggested that meridional shifts in the ITCZ ...