HR: 1330h
AN: T52B-0260    [PDF]
TI: Patterns of Heat Loss and Hydrothermal Recharge and Discharge Within 20-24 Ma Seafloor Offshore of the Nicoya Peninsula, Costa Rica, From Collocated Thermal and Seismic Data
AU: * MacKnight, R B
EM: bmacknight@es.ucsc.edu
AF: Earth Sciences Department University of California, Santa Cruz, 1156 High St, Santa Cruz, CA 95064
AU: Fisher, A T
EM: afisher@es.ucsc.edu
AF: Earth Sciences Department University of California, Santa Cruz, 1156 High St, Santa Cruz, CA 95064
AU: Hutnak, M
EM: mhutnak@es.ucsc.edu
AF: Earth Sciences Department University of California, Santa Cruz, 1156 High St, Santa Cruz, CA 95064
AU: Silver, E
EM: esilver@es.ucsc.edu
AF: Earth Sciences Department University of California, Santa Cruz, 1156 High St, Santa Cruz, CA 95064
AU: Stein, C
EM: cstein@uic.edu
AF: Dept. of Earth and Environmental Sciences (M/C 186) University of Illinois at Chicago, 845 West Taylor St., Chicago, IL 60607
AU: Harris, R
EM: rnharris@mines.utah.edu
AF: Dept. of Geology and Geophysics University of Utah, 717 W.B.B., Salt Lake City, UT 84112
AU: Costa Pisani, P
EM: patrizia@hawaii.edu
AF: University of Hawaii Geology and Geophysics Dept., 1680 East-West Rd., POST 807, Honolulu, HI 96822
AU: Deshon, H
EM: hdeshon@es.ucsc.edu
AF: Earth Sciences Department University of California, Santa Cruz, 1156 High St, Santa Cruz, CA 95064
AU: Hasterok, D
EM: dhasterok@mines.utah.edu
AF: Dept. of Geology and Geophysics University of Utah, 717 W.B.B., Salt Lake City, UT 84112
AU: Ellsworth, C
EM: cindy.ellsworth@hotmail.com
AF: Pacific Geoscience Center, GSC, 9860 W. Saanich Rd., Sydney, B.C V8L4B2 Canada
AB: The TicoFlux II expedition investigated seafloor hydrothermal activity in the Cocos Plate offshore the Nicoya Peninsula, Costa Rica, and its influence on the thermal state of the upper lithosphere prior to subduction. This program focused on the role of seamounts in guiding hydrothermal recharge and discharge, and complements a regional study completed a year earlier in which the nature of the thermal transition between East Pacific Rise-generated and Cocos-Nazca-generated seafloor was documented. In this presentation, we analyze seismic and heat flow data to illustrate characteristic thermal patterns associated with rapid fluid flow in upper basement rocks. Fluid flow can perturb the thermal state of the oceanic crust, depending on flow rate, flow depth, and proximity to points of recharge or discharge. Hydrothermal recharge and discharge in this area is strongly guided by seamounts and other basaltic outcrops that penetrate regionally thick and continuous sediments. Areas of recharge are characterized by low heat flow values and subsequently low basement temperatures, with both heat flow and basement temperatures increasing with distance from recharge points. Areas of discharge are characterized by higher heat flow values, particularly in the vicinity of basement outcrops, and basement temperatures that remain relatively constant as the sediment-basement interface rises towards the seafloor. We also observe sites where local convection, confined to sediment-covered basement, homogenizes upper basement temperatures.
DE: 1744 Tectonophysics
DE: 9355 Pacific Ocean
SC: Tectonophysics [T]
MN: 2003 Fall Meeting