@article {Kluesner2013, title = {{High density of structurally controlled, shallow to deep water fluid seep indicators imaged offshore Costa Rica}}, journal = {Geochemistry, Geophysics, Geosystems}, volume = {14}, number = {3}, year = {2013}, month = {mar}, pages = {519{\textendash}539}, abstract = {We used high-resolution mapping to document 161 sites of potential fluid seepage on the shelf and slope regions where no geophysical seep indicators had been reported. Identified potential seabed seepage sites show both high-backscatter anomalies and bathymetric expressions, such as pockmarks, mounds, and ridges. Almost all identified seabed features are associated with bright spots and flat spots beneath, as mapped within the 3-D seismic grid. We obtained EM122 multi-beam data using closely spaced receiver beams and 4-5 times overlapping multi-beam swaths, which greatly improved the sounding density and geologic resolvability of the data. At least one location shows an acoustic plume in the water column on a 3.5 kHz profile, and this plume is located along a fault trace and above surface and subsurface seepage indicators. Fluid indicators are largely associated with folds and faults within the sediment section, and many of the faults continue into and offset the reflective basement. A dense pattern of normal faults is seen on the outer shelf in the multi-beam bathymetry, backscatter, and 3-D seismic data, and the majority of fluid seepage indicators lie along mapped fault traces. Furthermore, linear mounds, ridges, and pockmark chains are found on the upper, middle, and lower slope regions. The arcuate shape of the shelf edge, projection of the Quepos Ridge, and high density of potential seep sites suggest that this area may be a zone of former seamount/ridge subduction. These results demonstrate a much greater potential seep density and distribution than previously reported across the Costa Rican margin. {\textcopyright}2013. American Geophysical Union. All Rights Reserved.}, keywords = {Costa Rica, fluid flow, fluid seepage, Marine Geology and Geophysics, subduction zones}, issn = {15252027}, doi = {10.1002/ggge.20058}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84879641763\&partnerID=tZOtx3y1}, author = {Kluesner, Jared W. and Silver, Eli A. and Bangs, Nathan L. and McIntosh, Kirk D. and Gibson, James and Orange, Daniel and Ranero, Cesar R. and von Huene, Roland} } @article {Harris2010a, title = {{Thermal regime of the Costa Rican convergent margin: 1. Along-strike variations in heat flow from probe measurements and estimated from bottom-simulating reflectors}}, journal = {Geochemistry, Geophysics, Geosystems}, volume = {11}, number = {12}, year = {2010}, month = {dec}, pages = {n/a{\textendash}n/a}, abstract = {The thermal structure of convergent margins provides information related to the tectonics, geodynamics, metamorphism, and fluid flow of active plate boundaries. We report 176 heat flow measurements made with a violin bow style probe across the Costa Rican margin at the Middle America Trench. The probe measurements are collocated with seismic reflection lines. These seismic reflection lines show widespread distribution of bottom-simulating reflectors (BSRs). To extend the spatial coverage of heat flow measurements we estimate heat flow from the depth of BSRs. Comparisons between probe measurements and BSR-derived estimates of heat flow are generally within 10\% and improve with distance landward of the deformation front. Together, these determinations provide new information on the thermal regime of this margin. Consistent with previous studies, the margin associated with the northern Nicoya Peninsula is remarkably cool. We define better the southern boundary of the cool region. The northern extent of the cool region remains poorly determined. A regional trend of decreasing heat flow landward of the deformation front is apparent, consistent with the downward advection of heat by the subducting Cocos Plate. High wave number variability at a scale of 5-10 km is significantly greater than the measurement uncertainty and is greater south of the northern Nicoya Peninsula. These heat flow anomalies vary between approximately 20 and 60 mW m-2 and are most likely due to localized fluid flow through mounds and faults on the margin. Simple one-dimensional models show that these anomalies are consistent with flow rates of 7-15 mm yr-1. Across the margin toe variability is significant and likely due to fluid flow through deformation structures associated with the frontal sedimentary prism. Copyright 2010 by the American Geophysical Union.}, keywords = {fluid flow, heat flow, Middle America Trench, subduction zones}, issn = {15252027}, doi = {10.1029/2010GC003272}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-78650544794\&partnerID=tZOtx3y1}, author = {Harris, Robert N. and Grevemeyer, Ingo and Ranero, Cesar R. and Villinger, Heinrich and Barckhausen, Udo and Henke, Thomas and Mueller, Christian and Neben, Soenke} } @article {Harris2010, title = {{Thermal regime of the Costa Rican convergent margin: 2. Thermal models of the shallow Middle America subduction zone offshore Costa Rica}}, journal = {Geochemistry, Geophysics, Geosystems}, volume = {11}, number = {12}, year = {2010}, month = {dec}, pages = {n/a{\textendash}n/a}, abstract = {At the Costa Rica margin along the Middle America Trench along-strike variations in heat flow are well mapped. These variations can be understood in terms of either ventilated fluid flow, where exposed basement allows fluids to freely advect heat between the crustal aquifer and ocean, or insulated fluid flow where continuous sediment cover restricts heat advection to within the crustal aquifer. We model fluid flow within the subducting aquifer using Nusselt number approximations coupled with finite element models of subduction and explore its effect on temperatures along the subduction thrust. The sensitivity of these models to the initial thermal state of the plate and styles of fluid flow, either ventilated or insulated, is explored. Heat flow measurements on cool crust accreted at the East Pacific Rise are consistent with ventilated hydrothermal cooling that continues with subduction. These models yield much cooler temperatures than predicted from simulations initialized with conductive predictions and without hydrothermal circulation. Heat flow transects on warm crust accreted at the Cocos-Nazca spreading center are consistent with models of insulated hydrothermal circulation that advects heat updip within the subducting crustal aquifer. Near the trench these models are warmer than conductive predictions and cooler than conductive predictions downdip of the trench. Comparisons between microseismicity and modeled isotherms suggest that the updip limit of microseismicity occurs at temperatures warmer than 100{\textdegree}C and that the downdip extent of microseismicity is bounded by the intersection of the subduction thrust with the base of the overriding crust. Copyright 2010 by the American Geophysical Union.}, keywords = {fluid flow, subduction zones, thermal model}, issn = {15252027}, doi = {10.1029/2010GC003273}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-78650528793\&partnerID=tZOtx3y1}, author = {Harris, Robert N. and Spinelli, Glenn and Ranero, Cesar R. and Grevemeyer, Ingo and Villinger, Heinrich and Barckhausen, Udo} }