Deep Sea Drilling Project geothermal measurements; a review

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doi: 10.1029/RG025i008p01563
Author(s): Hyndman, R. D.; Langseth, M. G.; Von Herzen, R. P.
Author Affiliation(s): Primary:
Geol. Surv. Can., Pac. Geosci. Cent., Sidney, BC, Canada
Lamont-Doherty Geol. Obs., United States
Woods Hole Oceanogr. Inst., United States
Volume Title: Reviews of Geophysics
Source: Reviews of Geophysics, 25(8), p.1563-1582. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 8755-1209 CODEN: RGPSBL
Note: In English. Geol. Surv. Can.; Contrib. No. 16386. 85 refs.; illus. incl. 1 table, sketch map
Summary: In this article the geothermal measurements made from the scientific drilling ship Glomar Challenger are evaluated, edited, and reviewed. For a number of sites the heat flow values given in the Initial Reports of the Deep Sea Drilling Project have been revised; less than half of the boreholes in which thermal measurements were attempted gave reliable data. By the end of the Deep Sea Drilling Project (DSDP) in 1983, reliable borehole heat flow measurements had been obtained at some 80 sites in all of the world oceans except the Arctic. The reliable values are considered to represent the deeper heat flux to within 20%; for a few the accuracy is within 5%. Most temperature measurements have been obtained using probes penetrating the undisturbed sediments at the bottom of the hole at subbottom depths of between 75 m and 250 m, although some data have been obtained at depths less than 30 and over 1000 m. Temperatures have been obtained a significant distance into the crust in eight holes. The main general conclusions are as follows: (1) There are no large or systematic differences between borehole heat flow values and oceanographic probe values obtained nearby. Such a test of shallow-penetration oceanographic probe measurements was one of the first objectives of the DSDP heat flow program. (2) There are very few clear, smooth changes of borehole heat flow with depth in areas with thick sedimentary sections that are indicative of either long-term bottom water temperature changes (tens to thousands of years) or large heat production in the sediments. Vertical migration of sediment interstitial pore water is suggested by nonlinear temperature-depth profiles at a few sites, particularly where the sediment is relatively thin and the temperature gradient is high. (3) Temperatures in the crustal parts of deep-sea drill holes exhibit a wide range of behavior, generally indicating hydrothermal circulation in the upper crust. At five sites, seawater is inferred to be moving down the holes into the crust, indicating low formation pressures and very high permeability in the upper crust. In two deep holes, however, such flow is limited to above several hundred meters into the crust, and heat fluxes close to theoretical cooling lithosphere values for the age of the crust (6 and 7 Ma) are found at greater depth. These sites suggest that hydrothermal circulation may be concentrated at shallow depths in the crust. Summary tables are presented of the heat flow data considered to be reliable after review and revision, and an appendix provides detailed comments on all the measurements for which data are available. Geothermal measurements are continuing on the new Ocean Drilling Program ship JOIDES Resolution.
Year of Publication: 1987
Research Program: DSDP Deep Sea Drilling Project
Key Words: 07 Marine Geology and Oceanography; 18 Geophysics, Solid-Earth; 20 Geophysics, Applied; Catalogs; Crust; Deep Sea Drilling Project; Deep-sea environment; Geothermal gradient; Global; Heat flow; Hydrothermal conditions; Marine environment; Marine sediments; Measurement; Observations; Ocean floors; Oceanic crust; Programs; Review; Sediments; Tectonophysics; Temperature; Temperature logging; Thermal conductivity; Thermal properties; Well-logging; World ocean
Record ID: 1988015363
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.

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