Hoernle, Kaj; Abt, David; Fischer, Karen M; Nichols, Holly; Hauff, Folkmar; Abers, Geoffrey A; van den Bogaard, Paul; Heydolph, Ken; Alvarado, Guillermo; Protti, Marino; Strauch, Wilfried (2008): Geochemistry of oceanic crust beneath Costa Rica. PANGAEA, https://doi.org/10.1594/PANGAEA.773166, Supplement to: Hoernle, K et al. (2008): Arc-parallel flow in the mantle wedge beneath Costa Rica and Nicaragua. Nature, 451(7182), 1094-1097, https://doi.org/10.1038/nature06550
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Resolving flow geometry in the mantle wedge is central to understanding the thermal and chemical structure of subduction zones, subducting plate dehydration, and melting that leads to arc volcanism, which can threaten large populations and alter climate through gas and particle emission. Here we show that isotope geochemistry and seismic velocity anisotropy provide strong evidence for trench-parallel flow in the mantle wedge beneath Costa Rica and Nicaragua. This finding contradicts classical models, which predict trench-normal flow owing to the overlying wedge mantle being dragged downwards by the subducting plate. The isotopic signature of central Costa Rican volcanic rocks is not consistent with its derivation from the mantle wedge (Feigenson et al., 2004, doi:10.1029/2003GC000621; Herrstom et al., 1995, doi:10.1130/0091-7613(1995)023<0617:VILCAW>2.3.CO;2; Abratis and Woerner, 2001) or eroded fore-arc complexes (Goss and Kay, 2006, doi:10.1029/2005GC001163) but instead from seamounts of the Galapagos hotspot track on the subducting Cocos plate. This isotopic signature decreases continuously from central Costa Rica to northwestern Nicaragua. As the age of the isotopic signature beneath Costa Rica can be constrained and its transport distance is known, minimum northwestward flow rates can be estimated (~63-190 mm/yr) and are comparable to the magnitude of subducting Cocos plate motion (approx85 mm/yr). Trench-parallel flow needs to be taken into account in models evaluating thermal and chemical structure and melt generation in subduction zones.
Median Latitude: 9.575414 * Median Longitude: -84.916831 * South-bound Latitude: 7.470000 * West-bound Longitude: -86.200000 * North-bound Latitude: 11.059300 * East-bound Longitude: -81.447000
Date/Time Start: 1996-11-08T14:00:00 * Date/Time End: 1996-11-18T12:00:00
170-1039C * Latitude: 9.639700 * Longitude: -86.200000 * Date/Time Start: 1996-11-08T14:00:00 * Date/Time End: 1996-11-11T01:15:00 * Elevation: -4351.4 m * Penetration: 448.7 m * Recovery: 37.65 m * Location: Costa Rica subduction complex, North Pacific Ocean * Campaign: Leg170 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 11 core; 85.6 m cored; 0 m drilled; 44 % recovery
170-1040C * Latitude: 9.661600 * Longitude: -86.178900 * Date/Time Start: 1996-11-11T05:30:00 * Date/Time End: 1996-11-18T12:00:00 * Elevation: -4177.9 m * Penetration: 665 m * Recovery: 377.28 m * Location: Costa Rica subduction complex, North Pacific Ocean * Campaign: Leg170 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 53 cores; 505.7 m cored; 0 m drilled; 74.6 % recovery
Datasets listed in this publication series
- Hoernle, K; Abt, D; Fischer, KM et al. (2008): (Table S1) Nd-Pb isotope ratios of oceanic crust beneath Costa Rica. https://doi.org/10.1594/PANGAEA.773163
- Hoernle, K; Abt, D; Fischer, KM et al. (2008): (Table S1) Nd-Pb isotope ratios of oceanic crust in ODP Hole 170-1039C and 170-1040C. https://doi.org/10.1594/PANGAEA.773165