Heat Flow Measurements, DSDP Leg 37

Hyndman, R. D.; Herzen, R. P. Von; Erickson, A.J.; Jolivet, Joël

doi:10.2973/dsdp.proc.37.108.1977

Cited by 22 publications

(20 citation statements)

References 36 publications

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“…However, deep borehole observations of temperature and hydrologic processes within the oceanic crust are limited to a few sites, namely Deep Sea Drilling Project (DSDP) Holes 504B and 395A (Hyndman et al, 1976(Hyndman et al, , 1977Becker et al, 1983Becker et al, , 1984. Fine-scale observations of boreholes in the oceanic environment have recently become available with the advent of high-resolution temperature logging tools (TLTs).…”

Section: Introductionmentioning

confidence: 99%

Thermal and Hydrologic Properties of Old Oceanic Crust in Hole 765D, Argo Abyssal Plain, Indian Ocean

Castillo¹

1992

Proceedings of the Ocean Drilling Program

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With a few exceptions, our knowledge of heat flow within the oceanic lithosphere comes from seafloor measurements using techniques that include sediment probes and coring. Borehole temperature-logging technology has been remarkably successful in continental boreholes, and has only recently been exploited by the ODP community. Borehole temperature measurements are valuable because the data gathered allow us to investigate how heat transfer (conductive and/or convective) varies with depth. For this reason, fine-scale, high-resolution temperature profiles were measured in Hole 765D to document the thermal and hydrologic properties of 140-Ma-old oceanic crust in the Indian Ocean near the northwestern shelf of Australia. Three complete temperature logging runs were conducted employing the new temperature logging tool (TLT), which is now standard logging equipment aboard JOIDES Resolution. The results indicate an average heat flow for the sediment section (0-932 mbsf) of 52.8 ± 5.7 mW/m 2 . This heat flow is slightly higher (~9 mW/m 2 ) than both regional heat-flow measurements and the heat flow predicted by a conductive cooling model. Temperature profiles for the basalt section (932-1195 mbsf) are each associated with temperature inversions and intervals (10-50 m) of near-constant temperatures. The computed equilibrium temperature profile is thermally depressed in excess of a few degrees Celsius compared with an expected profile assuming a conductive and steady-state heat-flow regime. The major source of this thermal perturbation appears to be formation fluid that enters the borehole near the sediment/basalt interface and eventually flows downhole and into the basalt formation, presumably through open fractures. The flow is generally restricted to the upper 150 m of the basalts. Based on these thermal and hydrologic observations, the shallow section of the oceanic crust at this site is believed to be permeable and slightly underpressured (fluid pressure less than hydrostatic).

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Section: Introductionmentioning

confidence: 99%

Thermal and Hydrologic Properties of Old Oceanic Crust in Hole 765D, Argo Abyssal Plain, Indian Ocean

Castillo¹

1992

Proceedings of the Ocean Drilling Program

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“…48C). The samples from the igneous rocks cluster about the model curve for a grain thermal conductivity of 1.7 W/m K, which is typical for relatively fresh basaltic rocks (Hyndman et al, 1977). The thermal conductivities of the sediments, on the other hand, appear to require grain thermal conductivities as high as 4 W/m K. Calcite has a grain thermal conductivity of about 5 W/m K, and quartz has a grain thermal conductivity of 10 W/m K. A significant component of carbonate and/or quartz is indicated.…”

Section: Physical-property Correlationsmentioning

confidence: 99%

Site 797

1990

Proceedings of the Ocean Drilling Program

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1 Tamaki, K., Pisciotto, K., Allan, J., et al., 1990. Proc. ODP, Init. Repts., 127: College Station, TX (Ocean Drilling Program). Principal results: The objectives at Site 797, located in the southern Yamato Basin, were (1) to determine the age and nature of acoustic basement, (2) to measure the direction and magnitude of the present stress field, and (3) to characterize the sedimentation, subsidence, and oceanographic evolution of the area. The results at Site 797 are summarized below and in Figure 1. The principal results at Site 797 are as follows:1. Acoustic basement and an overlying seismic interval at this site comprise basalts and dolerites and interlayered volcaniclastic sandstones, siltstones, and silty claystones. The age of the sediments which overlie the shallowest basalt layer is estimated to be about 19 Ma. Based on paleodepth estimates using microfossils within these sediments and the sedimentologic interpretation of the underlying volcaniclastic sediments, this part of the Yamato Basin probably subsided rapidly during the early Miocene. The uppermost basalts most likely represent submarine lava flows, whereas the bulk of the underlying igneous units are sills and dikes. The upper nine units are high-Al basalt in composition, consistent with generation during the early stages of arc rifting. However, the units below these are mildly alkaline basalts and enriched tholeiites, which are unrelated to the overlying basalts and were probably derived from a different mantle source.2. The in-situ stress field could not be determined, because poor hole conditions precluded packer/hydro fracture tests. A borehole televiewer log over one basalt interval showed fractures but no borehole breakouts for stress directions.3. The lithologic and paleontological data indicate at least four principal stages in the evolution of this part of the Yamato Basin: (a) an early Miocene period of submarine basaltic volcanism and concomitant deposition of gravity-flow and current-reworked volcani- 323 SITE 797clastic sandstones and siltstones on a shelf or slope, probably outboard of a delta; (b) a late early to early middle Miocene phase of diminishing submarine volcanic activity, warm surface waters, and deposition of calcareous and slightly phosphatic hemipelagic claystones at lower middle bathyal depths (1500-2000 m) in a poorly oxygenated basin; (c) a late Miocene to late Pliocene cooling period beginning with an interval of anomalously slow sedimentation (5 m/m.y.) or a hiatus and characterized by dominant but variable diatomaceous sedimentation at lower middle bathyal depths (1500-2000 m); and (d) a latest Pliocene to Holocene stage during which diatomaceous sedimentation diminished volcanic-ash production and terrigenous input increased, subsidence continued, and climate oscillated to produce a sequence of interlayered light-and dark-colored silty clays having variable organic-carbon contents. In contrast with the more northern sites drilled during Leg 127, the sediments at Site 797 contain more carbonate suggesting ...

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“…Figure 44 shows the conductivity values plotted vs. porosity. The basement values (solid dots) are best fit by a solid component conductivity of 1.7 W/m K, which is typical for basaltic rocks (e.g., Hyndman et al, 1977). On the other hand, Figure 44 suggests that the thermal conduc- tivity of the solid component of the silty claystone is 3-4 W/m • K, indicating that these sediments may contain significant amounts of quartz and/or carbonates, which are common rockforming minerals with high conductivities.…”

Section: Physical Properties Of the Igneous Unitsmentioning

confidence: 94%

Site 795

1990

Proceedings of the Ocean Drilling Program

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Heat Flow Measurements, DSDP Leg 37

Cited by 22 publications

References 36 publications

Thermal and Hydrologic Properties of Old Oceanic Crust in Hole 765D, Argo Abyssal Plain, Indian Ocean

Thermal and Hydrologic Properties of Old Oceanic Crust in Hole 765D, Argo Abyssal Plain, Indian Ocean

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