New marine heat flow measurements at the Costa Rica Rift, Panama Basin

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Author(s): Harris, R. N.; Kolandaivelu, K. P.; Gregory, Emma P. M.; Alshafai, Redha; Lowell, R. P.; Hobbs, R. W.
Author Affiliation(s): Primary:
Oregon State University, Corvallis, OR, United States
Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
University of Durham, Durham, United Kingdom
Volume Title: AGU 2016 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2016; American Geophysical Union 2016 fall meeting, San Francisco, CA, Dec. 12-16, 2016. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: We report new heat flow measurements collected along the southern flank of the Costa Rica ridge. This ridge flank has been the site of numerous seismic, heat flow, and ocean drilling experiments and has become an important type location for investigations of off-axis hydrothermal processes. These data were collected as part of an interdisciplinary NERC and NSF-funded collaboration entitled: Oceanographic and Seismic Characterization of heat dissipation and alteration by hydrothermal fluids at an Axial Ridge (OSCAR), to better understand links between crustal evolution, hydrothermal heat loss and the impact of this heat loss and fluid mass discharge on deep ocean circulation. The heat flow measurements are collocated with a newly acquired high-resolution seismic profile collected using a GI-gun source to image the sedimentary and upper crustal section. The profile is tied to ODP Hole 504B and provides robust estimates of the sediment thickness as well as its internal structure. In total five heat flow stations consisting of 67 new heat flow measurements were made, spanning crustal ages between 1.3 and 5.4 Myr. The full spreading rate of ≈66 mm/yr gives rise to abyssal hill basement relief between ≈500 and 250 m. Sediment cover is relatively incomplete in this region and varies between 0 and 290 m. The majority of heat flow values fall below half-space cooling models indicating that significant amounts of heat are removed by hydrothermal circulation. Low heat flow values are observed in sediment ponds between abyssal hill relief and high values are generally associated with ridge-ward dipping faults bounding abyssal hills. These faults are likely high permeability pathways where heated fluids are discharging, providing an example where large-scale faulting and block rotation plays a major role in ventilated ridge flank fluid circulation. The heat flow fraction (qobs/qpred) varies between varies between 0.01 and 4.1 and has a mean of 0.3 indicating that on average 70% of the expected heat is advected. The mass flux associated with this heat advection is ≈5 x 10-6 kg/m2-s assuming temperature discharge on the ridge flank is 10° C above ambient.
Year of Publication: 2016
Research Program: ODP Ocean Drilling Program
Key Words: 18 Geophysics, Solid-Earth; Costa Rica Rift; DSDP Site 504; East Pacific; Equatorial Pacific; Heat flow; North Pacific; Northeast Pacific; Ocean Drilling Program; Pacific Ocean; Panama Basin
Coordinates: N011335 N011338 W0834348 W0834357
Record ID: 2017066534
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