25. DOWNHOLE TEMPERATURE AND SHIPBOARD THERMAL CONDUCTIVITY MEASUREMENTSABOARD D/V GLOMAR CHALLENGER IN THE RED SEA

Ron W. Girdler, School of Physics, The University, Newcastle upon Tyne , United Kingdomand

Al J. Erickson and Richard Von Herzen, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts

ABSTRACT

Successful downhole temperature measurements were made atSites 225, 227, and 228, enabling reasonably good estimates ofthe temperature gradient at Sites 225 and 227 and a less reliableestimate at Site 228. In addition, an estimate of the minimumtemperature gradient was obtained for Site 229 by measuring thetemperatures of sediments in the core catchers.

On the cores of soft carbonate nanno oozes, 53 thermalconductivity measurements were made (18 for Site 225, 12 forSite 227, and 23 for Site 228). The mean of all the measurementsis 1.315 Wm-1 K-l.

The temperature gradients and conductivities enable the heatflow to be estimated at four of the six DSDP sites in the Red Sea.Heat flow values are all higher than the world mean, ranging from105 to more than 251 mWπr2.

These new measurements increase the total number of heatflow values for the Red Sea to 21. A new listing is given togetherwith an updated map of heat flow values.

INTRODUCTION

During Leg 23, it was possible to obtain useful estimatesof heat flow at four of the six sites drilled in the Red Sea.These increase the number of heat flow measurements inthe Red Sea to 21. Previous work has been reviewed byGirdler (1970) who listed 12 measurements made with heatflow probes from survey ships and 5 estimates fromtemperature data taken in exploration boreholes. All butone of the 17 values show that the Red Sea has higher thannormal heat flow. The axial, deep trough seems to haveparticularly high heat flow, the highest value being greaterthan 3306 mWm-2 (Erickson and Simmons, 1969). Thehigh heat flow also seems to extend over the margins, thevalues for the five exploration boreholes all being abouttwice the world mean.

Downhole temperatures were measured at Sites 225(two values), 227 (four values), and 228 (three values) usinga temperature probe designed at the Woods Hole Oceano-graphic Institution and described by Erickson (1973). Itwas not possible to obtain any measurements at Site 226because of the early penetration of hard basalt. It alsoproved impossible to obtain temperature measurements atSites 229 and 230 mainly because of bad weather (windspeeds of 50 mph). An attempt was made to obtain ameasurement at 108 meters below bottom at Site 229, butthe probe bent because of the presence of hard volcanictuffs, and the recorder failed to switch on. The bumpersubs became sanded up and further attempts to obtainmeasurements with the probe were abandoned. A minimumestimate of the heat flow was obtained at Site 229 by

making crude measurements of the temperature of thematerial in the core catcher using a very simple thermom-eter as soon as the cores arrived on deck. Site 230 had to beabandoned prematurely because of bad weather so notemperature estimates were possible.

A total of 53 measurements of thermal conductivity ofthe soft sediments from Sites 225, 227, and 228 was madeaboard the D/V Glomar Challenger using a needle-probemethod. Measurements of thermal conductivities of theanhydrite and halite found beneath the soft sediments aredescribed in an accompanying paper (Wheildon et al., thisvolume).

The measurements of down-hole temperatures andthermal conductivities aboard ship enabled reasonableestimates of the geothermal heat flux to be obtained forSites 225, 227, and 228 and a very rough minimumestimate for Site 229.

DOWNHOLE TEMPERATURE MEASUREMENTS

The temperature probe was generally lowered to thebottom of the drill string on the sand line during a pause indrilling operations. The instrument is designed such that atemperature measurement may be obtained at the sametime as a core. On this leg, the heat flow probe was foundto be too delicate to withstand the rigors of the coringoperations, and it was altogether more satisfactory to makea separate operation of the heat flow measurement. Thiswas economically feasible because of the relatively shallowwater depths at the drill sites (less than 2 km).

879

R. W. GIRDLER, A. J. ERICKSON, R. VON HERZEN

A description of the instrument and its operation can befound in the DSDP Leg 19 Initial Report (Erickson, 1973).It is sufficient to mention here that the instrument has aprobe containing a thermistor and a recording device whichenables temperature to be recorded as a function of timewhile the thermistor probe is in the thermally undisturbedsediment at the bottom of the hole. The latter facilityenables the quality of the data to be assessed for eachdownhole measurement.

In the following discussion of the downhole tempera-tures at the various sites, the temperature-time plots(Figures 1 to 3) are presented for each measurement. Onthe figures, temperature estimates are given to 0.01°C andin the text these are rounded to 0.1 °C. Errors are given inthe text and are estimated from consideration of thetemperature-time records and calibration uncertainties.

It is noted that the temperatures recorded with thedownhole temperature probe for the bottom water (22.3°to 22.4°C at Sites 225, 227, and 228) seem a little high.For example, Siedler (1969) gives temperatures of about21.8°C for similar water depths. It is thought the discrep-ancy might be due to some confusion concerning thethermistor coefficients. As the other downhole tempera-tures would be similarly affected, the small discrepancy hasa negligible effect on the estimates of the temperaturegradients.

Site 225

Site 225 (latitude 21.31°N, longitude 38.25°E) has awater depth of 1228 meters, and downhole temperatureswere obtained at 19 and 78 meters subbottom. An attemptto obtain a temperature measurement at 45 meters failed,the apparatus not switching on. The temperature-timeplots for the two successful measurements are shown inFigure 1.

For the first measurement (19 m), the apparatus wasswitched on before penetrating the sediment to gain an ideaof the full cycle of the operation. The graph shows thedecrease in temperature as the probe is lowered down tothe bottom of the drill string, a steady temperature near thebottom (22.3 ± 0.1°C), and then the increase in tempera-ture as the probe is lowered into the sediment. Thesediment temperature is read to be 24.2 ± 0.1 °C.

For the measurement at 78 meters, the instrumentswitched on later giving a bottom temperature of 22.3 ±0.1°C. A small portion of the record was lost, probablybecause of the unusually large accelerations during penetra-tion due to rock fragments in the sediments. A maximumtemperature of 29.2 ± 0.2°C was recorded and this is takento be the minimum temperature of the sediment, as thetemperature curve suggests there was some slight disturb-ance after penetration.

The temperatures are plotted against subbottom depthsin Figure 4 and lie on a straight line giving a thermalgradient of 92 K km-l.

Site 227

Site 227 (latitude 21.33°N, longitude 28.13°E) has awater depth of 1795 meters. Four downhole temperatureswere obtained at 37, 73, 82, and 159 meters. Thetemperature-time curves for these are shown in Figure 2.

3 0 -

2 8 -

26

2 4 -

2 2 -

3 0 -

_

—Probeloweredon line

\

1

Loweronto ibottom/

S1

24l8βC

IjPenetration

22 35°Ci

TE

19

i

225

m.

iI0 20 30

T I M E (min)

4 0

UJ 2 8er

Si 2 6 -

2 4 -

2 2 -

-

-

-

Loweronto

- bottom\j

29I7°C

J

j—Penetration

/22•32°C

I i

s TE 225

78 m.

i i

I0 20 30

TIME (min)4 0

Figure 1. Temperature-time graphs for downhole tempera-tures recorded at subbottom depths of 19 and 78 metersat Site 225.

Some difficulty was experienced with penetration of theprobe due to the hardness of the bottom, the Master CoreInventory having descriptions such as "firm gray ooze" (36m), "stiff gray mud, slow coring" (72 m), and "hard mud"(82 m).

The temperature-time curve for the measurement at 37meters illustrates this problem; the curve suggests the probewas disturbed and there are three possible temperatures toread. As there is little decay after reaching the highest value(26.2 ± 0.1 °C) it seems that the probe finally penetratedrelatively undisturbed sediment having previously recordeddisturbed temperatures. It therefore seems logical to choosethe highest reading.

The temperature-time curve for 73 meters shows thatthe equilibrium temperature of the sediment was notreached. It seems likely the probe was pushed up into thecore barrel as evidenced by the sudden decrease intemperature after the maximum of 29.72°C was reached.The sediment temperature is therefore greater than29.72°C. Possible confirmation of this comes from thetemperature subbottom depth plot in Figure 5 where it isseen that the temperature for 73 meters plots below theline joining the sea bottom and deeper downholetemperatures.

880

30

28

<er.

£26üJ

2 4 -

2 2 -

SITE 227

37 m

DOWNHOLE TEMPERATURE AND SHIPBOARD THERMAL CONDUCTIVITY MEASUREMENTS

31 97°C

30

2490βC

Penetration

' 22-32 to 22-41 °C

I0 20 30TIME (min)

40

3 0 -

£28

2 4 -

22

- 29 72°C

\ Probe sucked into

/—Penetration

ontobottom J

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73

227

m.

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T I M E (mm)

40

Q. V

y 26

24

22

A MA SITE 227

82 m.

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R. W. GIRDLER, A. J. ERICKSON, R. VON HERZEN

SITE 22826

2 24

22

- 24 72°C

I—Penetration

2 5 m

0 I0

à4

22

2667°C

/—Penetration

J---22Z5"C1

20TIME

1

30(min)

SITE

61

4 0

228

m

iI0

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oLU

a: 3 6 -t-<

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| 32LUI -

28

24

20 30TIME (min)

Probe suckedinto core barrel ?

40

offbottom

SITE 228

97 m

I0 20 30TIME (min)

4 0

Figure 3. Temperature-time graphs for downhole tempera-tures recorded at subbottom depths of 25, 61, and 97meters at Site 228.

TEMPERATURE (°C)20 „ 30 40

kI0 l 5 2 0

E 50

100

150

92 K km"1

\

SITE 225

Figure 4. Temperatures plotted against subbottom depthsfor Site 225 together with thermal conductivities overthe depth range of the temperature measurements.

Three further attempts at measuring temperatures at thissite (subbottom depths of 133,174, and 228 meters) failed

20

3 50

100

150

\

TEMPERATURE (°C)30 40

1 r

k (Wm->K-1)

I0 l 5 2 0

o\

\\ 117 K km"1

\

\

\

\

SITE 227\

\\

°\

Figure 5. Temperatures plotted against subbottom depthsfor Site 227 together with thermal conductivities overthe depth range of the temperature measurements.

due to malfunctioning of the apparatus. This was mostunfortunate as it is seen from the temperature-depth plot(Figure 6) that, unlike for the previous sites, the points donot lie on a line, and the data do not seem sufficientlyunambiguous to exclude the possibility of nonlineargradients due to possible hydrothermal circulations at thissite. The best that can be done is to accept the maximumtemperature gradient (186 K km- 1 ) obtained by taking thebottom water temperature and the maximum temperatureof 40.4°C obtained at 97 meters subbottom depth. Asexpected from the temperature-time curve, the temperaturefor 61 meters plots below this line confirming that theprobe was disturbed. It is noted that the gradient is thehighest recorded for all the sites.

Site 229As mentioned in the introduction, it was hazardous to

use the downhole temperature probe at Site 229 (latitude14.77°N, longitude 42.19°E) because of the adverseweather conditions and the shallow water depth of 852meters. The one attempt to use the probe at a subbottomdepth of 109 meters failed, the probe becoming bentpossibly due to the presence of hard volcanic tuffs (the siteis near Zebayir Island). It was noticed that the sediment inthe core catcher felt warm to the touch; therefore, threetemperature measurements were made by inserting a crudethermometer into the core catcher sediment as soon as thecores arrived on deck. These gave temperatures of 29°C at74 meters, 28°C at 83 meters, and 39°C at 212 meterssubbottom depths. These temperatures are plotted againstsubbottom depths in Figure 7 and give reasonable gradients.It is probably safe to conclude that the minimum tempera-ture gradient at Site 229 is 99 K km"1.

THERMAL CONDUCTIVITIES

Thermal conductivities of the soft sediments from Sites225, 227, and 228 were measured aboard D/V GlomarChallenger using the needle-probe method (Von Herzen and

882

DOWNHOLE TEMPERATURE AND SHIPBOARD THERMAL CONDUCTIVITY MEASUREMENTS

20

50

I O O -

150

TEMPERATURE (°C)30 40 2 0

W

? o \\

186 K km"1

99Kkm"' \\

SITE 228

Figure 6. Temperatures plotted against subbottom depthsfor Site 228 together with thermal conductivities overthe depth range of the temperature measurements.

Maxwell, 1959). The cores from the other sites provedunsuitable—Site 226 cores yielding igneous rocks, coresfrom Site 229 having a high gas content, and Site 230 coresyeilding only one and a half core barrels of disturbedsediment.

Strip-chart recordings of needle-probe temperatureversus time were digitized and the times and temperaturesfitted to a curve of the form

where T is the temperature, t is the time, and A, B, C arecoefficients determined using a nonlinear regressionprogram.

These computed values are for the pressure and tempera-ture conditions of the laboratory, and it is necessary toconvert these to the conditions at the appropriate depth inthe drill hole. This is done using the correction factors givenby Ratcliffe (1960) and modified for use in drill holes byErickson (1973). The relationship is:

Corrected _ MeasuredConductivity Conductivity X

1 +W + pH

U82900;

Tw +— -

400

where

W = water depth (rri)p = mean sediment density (g/cm3)H = drill hole depth (m)Tw = bottom water temperature (°C)dt/dz = mean geothermal gradient (°Cm-!)^lab = laboratory ambient sediment temperature (°C)

50

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100

150

2 0 0

TEMPERATURE (°C)30 40r

w

\ v\ *76Kkm- v ~

\ \\ \ \

\\

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\82K km"1

\\

\

\

SITE 229

Figure 7. Crude temperature measurements of the materialin the core catcher giving minimum estimates for thetemperature gradient at Site 229.

The parameters used for Sites 225, 227, and 228 aregiven in Table 1. The environmental corrections are only afew percent and uncertainties in these parameters arenegligible for most purposes.

The environmentally corrected conductivities for thethree sites (225, 227, and 228) are shown plotted as afunction of depth in Figure 8, and numerical listings ofboth uncorrected and corrected values are given in Tables 2,3,and 4.

The description of the lithologies are for Site 225,"detrital clayey silt rich carbonate nanno ooze and chalk";for Site 227, "carbonate nanno ooze and chalk"; and forSite 228, "silty nanno-foram carbonate ooze and chalk andcalcareous siltstone." The ages range back into the earlyPliocene. It is seen from Figure 8 that the thermalconductivities for Site 225 show much less scatter than forSites 227 and 228 suggesting the sediments are morehomogeneous at Site 225. For Site 228 the thermal

883

R. W. GIRDLER, A. J. ERICKSON, R. VON HERZEN

THERMAL CONDUCTIVITY (Wm^K"1)

15 20 I 0 15 2 0 I0 15 2 0

TABLE 2Thermal Conductivities for Site 225

(m.)

I

tüJQ

lI0

CDCDZ)co

50

100

150

200

250

I I

_•

••

_225 227 228 "

Figure 8. Thermal conductivities plotted against sub-bottom depths for Sites 225, 227, and 228.

TABLE 1Site Parameters for Environmental Corrections

WaterDepth

Site (m)

WaterTemperature

°

Geothermal SedimentGradient Density(°C/m) (g/cm3)

225 1228

227 1795

228 1038

21.6

21.6

21.6

0.089

0.118

0.186

1.8

1.9

1.9

conductivities are somewhat higher, and the plot shows atendency for the conductivity to increase with depth. Themean conductivities (with standard deviations) for the threesites are given in Table 5.

HEAT FLOW

With the above experimental data, estimates can beobtained for the heat flow at Sites 225,227, 228, and 229.As the heat flow is the temperature gradient multiplied bythe thermal conductivity, these are shown together inFigures 4, 5, and 6 for Sites 225, 227, and 228,respectively. Figure 7 shows the estimates of the minimumtemperature gradients for Site 229; no thermal conductivitymeasurements are available due to the degassing of thecores from this site.

The values of the temperature gradients and conduc-tivities used to determine the heat flow at the four sites arelisted in Table 6. It is somewhat difficult to assign realisticestimates of the errors associated with these values. Theestimates for the four sites are discussed in turn.

For Site 225 (Figure 4) the temperature gradient isestimated as 92 ± 4 K k m - 1 , but it is noted that thisdepends on only three measurements. The thermal conduc-tivity for the depth range corresponding to the tempera-

Core

45689

10111213151617181920212223

Core

268

131520212223242526

Section

555252515223332232

Section

211213431622

Position(cm)

10010080

1008080408075777778686878

1016560

SubbottomDepth

(m)

30344348616578778497

106117126135142146162169

TABLE 3

MeasuredConductivity(Wm l K"1)

1.0641.2141.2111.2110.9801.1891.1231.1171.0381.1431.2311.2381.2611.2001.0871.0971.1051.097

Thermal Conductivities for Site 227

Position(cm)

8015015081

105477773

140959080

SubbottomDepth(m)

38476592

109152158162169184187196

MeasuredConductivity(Wirr1 K'1)

1.2811.5171.4661.1081.0981.2801.1531.0030.8491.2851.3350.907

CorrectedConductivity(Wm-1 K"1)

1.0741.2171.2221.2180.9931.2031.1431.1381.0581.1701.2621.2721.2951.2391.1231.1351.1451.135

CorrectedConductivity(Wm•l K-1)

1.3011.5511.5091.1401.1361.3411.1561.0050.8521.3641.4150.965

tures is taken as the mean of the top 10 measurementsgiving 1.144 ± 0.075 Wm•l K-1, i.e., somewhat less than themean value of 1.171 ± 0.079 Wm"1 K"1 for all the valuesfrom Site 228 (Table 5). The heat flow is thus 105 ± 11mWm-2.

For Site 227 (Figure 5) the temperature gradient isestimated as 117 ± 8 K km-1; this is slightly weighted infavor of the higher values (cf. the straight line drawn inFigure 5). There are seven thermal conductivity measure-ments over the 160-meter depth range of the temperaturemeasurements and these give a mean of 1.305 ± 0.161Wm-1 K-l. The heat flow is thus 153 ± 29 mWπr^ theexperimental error of just less than ±20% is consideredreasonable and acceptable.

For Site 228 there is the problem of the choice oftemperature gradient as evidenced by the temperature-subbottom depth graphs in Figure 6. Following thediscussion in the section on downhole temperaturemeasurements, the higher gradient is chosen as the mostlikely. The thermal conductivity over the depth range ofthe measurements is taken as 1.348 ± 0.108 Wm"1 K"1.

884

DOWNHOLE TEMPERATURE AND SHIPBOARD THERMAL CONDUCTIVITY MEASUREMENTS

TABLE 4Thermal Conductivities for Site 228

Core

4567

10111314151618192022232425262728293031

Section

32424322222334232424444

Position(cm)

79788583

077

07872767777767079559349

10538657465

Site

225

227

228

SubbottomDepth i

(m)

28354754748298

107116126146154159178184195202214221232241250259

TABLE 5

MeasuredConductivity(Wm-1 K"1)

1.1941.2521.491

-1.3871.2131.3101.0351.4271.3491.5431.3801.4881.2401.4431.6081.5391.7401.3291.7081.6081.4911.592

Site Mean ThermalConductivities

Conductivities(Wπr1 K"1)

1.171 ± 0.079

1.252 ± 0.205

1.522 ± 0.219

(N = 18)

(N = 12)

(N = 23)

CorrectedConductivity(Wm-1 K-1)

1.2081.2721.523

-1.3951.2611.3061.0891.5031.4251.6411.4641.5841.3371.5361.7531.6911.9251.4791.9051.7921.6681.788

These values give a somewhat questionable heat flow of 251mWπr2. It is not realistic to quote an experimental error onthis value because of the difficulty with the temperaturegradient.

For Site 229, only the rough minimum temperatureestimates are available. From Figure 8, it is reasonable toassume that the temperature gradient is greater than 100 Kkm-1. As there are no thermal conductivity measurementsfor this site, the mean thermal conductivity of 1.266 Wirr1

K-l for Sites 225, 227, and 228 calculated from the valuesin Table 6 is assumed. The heat flow at Site 229 is thusgreater than 127 mWnr2.

The heat flow results are summarized in Table 6.

TABLE 6Heat Flow for Red Sea Deep Sea Drilling Sites

TemperatureGradient

Site (K km"1)Conductivity(Wm"1 K"1)

Heat Flow(mWm-2)

225

227

228

229

92 ±

117 ±

?186

>IOO

4

8

1.144 ± 0.075

1.305 ± 0.161

1.348 ± 0.108

1.266

105+11

153 ± 29

?251

>127

DISCUSSION AND CONCLUSIONS

It is seen from Table 6 that the heat flow for all the RedSea drilling sites is considerably higher than the world meanof 63 mWm-2. The value for Site 225 is about 1.7 times;for Site 227, about 2.4 times; for Site 228, about 4 times;and for Site 229, at least 2 times the world mean. Thispattern is consistent with previous heat flow measurementsin the Red Sea listed by Girdler (1970). The list is updatedto include the D/V Glomar Challenger sites in Table 7,while Figure 9 shows a map of all the Red Sea heat flowvalues (complete to the end of 1972). The D/V GlomarChallenger sites are marked with solid circles. Perhaps themost interesting result is Site 229 (>127 mWπr2) whichshows for the first time that high heat flow is observed inthe southern part of the Red Sea (south of 15°N). It is seenthat the other results also conform to the pattern of thehighest values being near the central axis of the Red Sea. Itmay be safely concluded that in spite of the variousdifficulties, the heat flow at four of the six D/V GlomarChallenger drilling sites in the Red Sea is appreciably higherthan normal.

The significance of such results has been discussed byGirdler (1970). It is sufficient to mention here that the highheat flow is probably associated with a widening intrusivezone down the central axis of the Red Sea associated withthe movement apart of Arabia and Nubia and consequentsea floor spreading.

35 40 45

4 0 45

Figure 9. Heat flow map of the Red Sea from Girdler(1970) updated to include the Glomar Challengermeasurements.

885

R. W. GIRDLER, A. J. ERICKSON, R. VON HERZEN

Stationor Well

Designation

Co 9-113CH 43-24CH 61-167CH 61DSDP 227DSDP 2255234CH 61-153CH 61-154CH 61-155DSDP 228Durwara 1,25232Mansiyah 1Amber 1Co 9-112Co 9-1115231Dhunishub 1Secca Fawn 1DSDP 229

Latitude(°N)

25.4725.4023.3321.3721.3321.3120.4519.7219.5719.3819.0918.8118.4017.2216.3516.3416.2215.9715.7215.3914.77

TABLE 7Red Sea Heat Flow Measurements

Longitude(°E)

35.4936.1737.3338.0838.1338.2537.9238.6838.9838.9039.0037.6439.7842.3740.0140.4741.2141.5240.6240.1642.19

WaterDepth(km)

1.3352.2050.8262.01.7951.2280.8702.7041.2762.2071.038Shelf1.480ShelfShelf1.2230.9411.735ShelfShelf0.852

Heat Flow(mWm-2)

267>96176

>3306153105

?134335107

63?251

12644

111122

90180175140125

>127

Reference

Langseth and Taylor (1967)Birch and Halunen (1966)Erickson and Simmons (1969)Erickson and Simmons (1969)This paperThis paperSclater (1966)Erickson and Simmons (1969)Erickson and Simmons (1969)Erickson and Simmons (1969)This paperGirdler (1970)Sclater (1966)Girdler (1970)Girdler (1970)Langseth and Taylor (1967)Langseth and Taylor (1967)Sclater (1966)Girdler (1970)Girdler (1970)This paper

ACKNOWLEDGMENTS

We are most grateful to Lloyd Russill and Kirk van Allyn(electronics technicians) for invaluable help aboard the D/VGlomar Challenger and to Jane Dunworth (computerassistant at Woods Hole Oceanographic Institution) fordigitizing records and computing the thermal conduc-tivities. The development of instruments for this project issupported by National Science Foundation Grant GA28504.

REFERENCES

Birch, F. S. and Halunen, A. J., 1966. Heat flow measure-ments in the Atlantic Ocean, Indian Ocean, Mediter-ranean Sea and Red Sea. J. Geophys. Res., v. 71, p.583-586.

Erickson, A., 1973. Initial report on downhole temperatureand shipboard conductivity measurements, Leg 19, theDeep Sea Drilling Project. In Creager, J. S., Scholl,D.W., et al., Volume XIX: Washington (U.S. Govern-ment Printing Office), p. 643.

Erickson, A. and Simmons, G., 1969. Thermal measure-ments in the Red Sea hot brine pools. In Hot brines andrecent heavy metal deposits in the Red Sea: Degens,E. T. and Ross, D. A. (Eds.), New York (Springer-Verlag), p. 114-121.

Girdler, R. W., 1970. A review of Red Sea heat flow: Phil.Trans. Roy. Soc. Lond., A., v. 267, p. 191-203.

Langseth, M. G. and Taylor, P. T., 1967. Recent heat flowmeasurements in the Indian Ocean. J. Geophys. Res., v.72, p. 6249-6260.

Ratcliffe, E. H., 1960. The thermal conductivities of oceansediments. J. Geophys. Res., v. 65, p. 1535-1541.

Sclater, J. G., 1966. Heat flow in the north west IndianOcean and Red Sea. Phil. Trans. Roy. Soc. Lond., A., v.259, p. 271-278.

Siedler, G., 1969. General Corculation of Water Masses inthe Red Sea. In Hot brines and recent heavy metaldeposits in the Red Sea: Degens, E. T. and Ross, D. A.(Eds.), New York (Springer-Verlag), p. 131-137.

Von Herzen, R. and Maxwell, A. E., 1959. The measure-ment of thermal conductivity of deep-sea sediments by aneedle-probe method. J. Geophys. Res., v. 64, p.1557-1563.

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