Heat flow measured over the Juan de Fuca Ridge: Evidence for widespread hydrothermal circulation in a highly heat transportive crust

Journal Article · Mon Oct 10 00:00:00 EDT 1977 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JB082i030p04845· OSTI ID:7293230

Davis, E E; Lister, C R.B.

One hundred twelve heat flow measurements were made on a 100-km-square grid of seismic reflection profiles centered over the intersection of the northern Juan de Fuca ridge and the Sovanco fracture zone. Profile spacing was roughly 10 km, and heat flow stations were located at each track line intersection. South of the fracture zone the crust is young (0--1.8 m.y.), sediment cover is incomplete, and on average, heat flow is very low in comparison with that predicted by any reasonable model for lithosphere creation. Station to station heat flow variability is high and uncorrelated with local topography or structure, and the nature and magnitude of variability cannot be accounted for by the thermal effects of either heat flow refraction or rapid sedimentation. On the Explorer ridge flank, north of the fracture zone, the crust is older (3.3--6.6 m.y.) and fully sedimented. Large local variability in heat flow values still exists, but a relationship between heat flow and sediment thickness can be detected. On average, heat flow increases with decreasing sediment thickness, and although the variation is in the proper sense, the magnitude of the observed heat flow variation cannot be explained by simple conductive mechanisms, such as deposition of cold sediments. A similar relationship between heat flow and sediment thickness is observed for the sediment-filled axial valley on the Juan de Fuca ridge, and basement temperatures estimated there range between about 100/sup 0/ and 300/sup 0/C. On the Explorer ridge flank, open circulation is prevented by the thick and continuous sediment cover, and the heat flow average over the area (5.7 HFU, where 1 HFU=1..mu..cal cm /sup 2/s/sup -1/) should be a reliable estimate of the total conductive heat flux for this age crust (4.5 m.y. on average). This, with other reliable data points from the Pacific, supports a simple dependence of heat flow upon age of heat flow (HFU) =12.0/age/sup 1/2/ (m.y.).

• Research Organization: Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
• OSTI ID: 7293230
• Journal Information: J. Geophys. Res.; (United States), Vol. 82:30
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
58 GEOSCIENCES
EARTH CRUST
HEAT FLOW
HYDROTHERMAL SYSTEMS
OCEANIC CRUST
PACIFIC OCEAN
REFRACTION
SEDIMENTATION
SEISMIC WAVES
THERMAL CONDUCTION
TOPOGRAPHY
ENERGY TRANSFER
GEOTHERMAL SYSTEMS
HEAT TRANSFER
SEAS
SURFACE WATERS
150301* - Geothermal Exploration & Exploration Technology- Geophysical Techniques & Surveys
580202 - Geophysics- Volcanology- (1980-1989)