Deep Sea Drilling Project Initial Reports Volume 42, Part 1

IV. GEOPHYSICAL PROFILING, DSDP 42A

Gerald W. Bode, Scripps Institution of Oceanography, Deep Sea Drilling Project, La Jolla, California

INTRODUCTION

We obtained routine geophysical measurements dur-ing Leg 42A of the Deep Sea Drilling Project. Of the841 nautical miles covered from Malaga, Spain, to Is-tanbul, Turkey, geophysical data were collected on allbut the Bosporus Straits, and a short distance ap-proaching them. We were underway 35 per cent of thetime during the 41 days spent at sea. Careful planningand excellent geophysical survey data aided us in locat-ing the sites with a minimum expenditure of time. At afew sites strong winds and currents caused problems inpositioning the ship over the site.

The onboard instrumentation included a precisionecho sounder, magnetometer, seismic reflection pro-filer, and a satellite navigation system. They weremaintained and operated by the Deep Sea DrillingProjects technical staff in cooperation with the scien-tific party and the officers and crew of Global Marine,Inc.

NAVIGATION

A Magnavox Model MX702A-3 Satellite NavigationReceiver with an H-P 2100A computer was the mainsource for navigation information. The unit was used toautomatically obtain edited fixes during the cruise. Ce-lestial fixes were also routinely taken by the ship's of-ficers.

The preliminary ship's track was determined by thebridge officers from readings of the gyro-compass andspeed estimate (dead reckoning techniques) betweensatellite fixes. This track was subsequently edited andsmoothed. The smoothed track was digitized andspeeds and courses-made-good calculated. This infor-mation is listed in Table 1.

The accuracy of the track is variable but is ±40 me-ters in the area of a satellite fix. The accuracy is some-

what less in other areas depending upon the length oftime between fixes, weather and currents, and the ma-neuvering of the ship.

Strong winds and currents in the vicinity of Site 372caused some degregation in the navigational control.The smooth track is shown in Figure 1.

Bathymetry

Bathymetric profiles were obtained with a 16-kHzecho sounder using an EDO recorder. The pulse widthis 0.2 milliseconds and the sweep rate was one second.The topographic profile was drawn on the basis ofdepth readings, taken at 5-minute intervals. This pro-file is found at the bottom of Figure 2.

MagneticsTotal intensity measurements of the earth's mag-

netic field were obtained using a Geometries magne-tometer; the sensor was towed approximately 300 me-ters astern. In addition to an analog record, actualgamma counts were logged at 5-minute intervals.These digited values were then used to calculate the re-sidual anomalies. The magnetic profile is found at thetop of Figure 2.

Seismic Reflecting ProfileThe seismic reflection profiles were obtained utiliz-

ing two (10 cubic inches and 40 cubic inches) Boltpneumatic airguns. The Teledyne hydrophone arraywas towed approximately 330 meters behind the ves-sel. The return signals were passed through two BoltPA6 amplifiers and filter modules before being re-corded on two EDO Western Model 550 PrecisionBathymetric recorders. Our recorder was set on a 10-second sweep; the other on a 5-second sweep. The an-notated 10-second sweep records are shown in Figure3.

1171

TABLE 1 TABLE 1 - Continued

G. W. BODE

1172

GEOPHYSICAL PROFILING

TABLE 1 - ContinuedTABLE 1 - Continued

1173

G. W. BODE

TABLE 1 - Continued TABLE 1 - Continued

Time

201722002308

0 0013802500320040005350544065207300808092809541022123513261508154316181656180418421920194521062220

000

02160330040004200452060206230630063808581050112412561442152815481608175019402010203020402055215622452318

0000052011203260353

Latitude

35° 31.40'N35° 29.50'N35° 28.40'N

35° 27.50'N35° 25.30'N35° 23.20'N35° 22.40'N35° 21.40'N35° 19.10'N35° 18.90'N35° 17.90'N35° 16.70'N35° 15.70'N35° 14.10'N35° 13.60'N35° 12.90'N35° 10.20'N35° 07.70'N35° 02.30'N35° 00.50'N34° 59.00'N34° 57.30'N34° 54.50'N34° 52.80'N34° 50.90'N34° 49.70'N34° 49.90'N34° 48.10'N

34° 47.30'N34° 46.30'N34° 45.40'N14° 44.90'N34° 44.70'N34° 44.30'N34° 43.70'N34° 43.50'N34° 43.50'N34° 43.40'N34° 41.80'N34° 40.60'N34° 40.60'N34° 39.90'N34° 39.80'N34° 39.30'N34° 39.00'N34° 38.70'N34° 37.00'N34° 35.90'N34° 35.80'N34° 35.70'N34° 35.50'N34° 34.20'N34° 34.30'N34° 34.10'N34° 34.20'N

34° 34.20'N34° 34.30'N34° 34.20'N34° 34.10'N34° 34.10'N

Longitude

20°20°21°

21°21°21°21°21°22°22°22°22°22°22°22°23°23°

23°23°24°24°24°24°24°24°24°24°25°

25°25°26°26°26°26°26°26°26°26°27°27°27°27°28°28°28°28°28°29°29°29°29°29°29°29°29°

29°30°30°30°30°

39.60'W58.00'W10.10'W

Distance(miles)

1416.31431.41441.4

(5 May 1975)

18.90'W35.50'W47.60'W52.50'W59.20'W15.70'W17.20'W28.60'W34.70'W41.30'W54.90'W59.50'W04.80'W28.90'W37.70'W54.90'W01.00'W07.30'W14.00'W26.10'W32.90'W39.30'W43.90'W59.20'W13.10'W

1448.61462.31472.41476.41482.01495.61496.91506.21511.41516.81528.11531.91536.21556.11563.71578.81584.21589.51595.31605.61611.41617.01620.91633.51645.0

(6 May 1975)

30.90'W55.20'W08.10'W13.60'W17.00'W22.70'W35.10'W39.00'W39.60'W41.10'W05.10'W25.80'W32.00'W50.20'W09.60'W17.90'W21.60'W25.20'W42.80'W03.80'W09.10'W12.80'W14.60'W16.80'W28.00'W37.00'W43.00'W

1659.61679.61690.21694.81697.61702.31712.51715.71716.21717.41737.21754.31759.41774.41790.31797.21800.21803.21817.81835.11839.51842.51844.01846.21855.51862.81867.8

(7 May 1975)

51.00'W00.80'W04.60'W28.50'W33.30'W

1874.41882.51885.61905.31909.3

Speed(knots)

8.88.78.4

8.48.48.18.38.68.38.38.18.78.48.79.49.08.9

8.99.29.29.19.1.9.28.89.49.49.38.8

8.88.69.18.48.88.79.14.49.18.59.19.09.89.08.99.28.98.69.48.79.19.09.09.19.09.09.4

9.49.48.88.88.9

Course(degrees)

979697

99102102100100100

96104101

98989998

110111110106107106107110107

949493

93959694959393949395949093909496969794919199

12689918990

90929090

102

Time

0402040505120530065206550707173608360846085909521000103010461132120012081223123212551255

14441444150715461559161016201620

1830183018551953201022302332

000

0030011602100354041405420602094010001058123212521318141815001650171018582050225623152328

Latitude

34° 33.80'N34° 33.70'N34° 34.10'N34° 34.20'N34° 34.10'N34° 34.10'N34° 32.60 N34° 32.60•N34° 32.10^34° 30.90 fa34° 30.80"N34° 34.80^34° 35.40'N34° 36.90^34° 37.80^34° 42.40^34°45.50'N34° 46.40^34° 48.50^34° 47.70^34° 45.70'N34° 45.70'N

34° 45.70'N34° 45.70'N34° 48.10'N34° 52.30'N34° 54.00'N34° 53.20'N34° 52.30'N34° 52.30'N

34° 52.30'N34° 52.30'N34° 52.30'N34° 52.20'N34° 52.10'N34° 51.60'N34° 51.50'N

34° 51.7θ'N34° 51.9θ'N34° 51.9θ'N34° 52.00'N34° 51.90'N34° 51.90'N34° 51.60'N34° 51.60'N34° 51.60'N34° 51.50'N34° 50.90'N34° 50.10'N34° 49.90'N34° 49.70'N34° 49.40'N34° 49.20'N34° 49.20'N34° 49.20'N34° 48.90'N34° 48.40'N34° 47.40'N34° 46.90'N34° 48.70'N

Longitude

30°30°30°30°31°31°31°31°31°31°31°31°31°31°31°31°31°31°31°31°31°31°

31°31°31°31°31°31°31°31°

31°31°31°31°31°31°30°

30°30°30°30°30°30°29°29°29°29°28°28°28°28°28°28°27°27°27°27°26°26°26°

34.90'W35.40'W47.60'W50.90'W05.80'W06.40'W07.70'W13.00'W23.80'W24.90'W27.20'W35.40'W36.80'W40.70'W42.60'W45.30'W46.30'W46.30'W46.80'W46.40'W45.60'W45.60'W

(10 May

45.60'W45.60'W47.80'W48.70'W49.80'W49.00'W48.5 0'W48.50'W

(12 May

48.50'W48.50'W45.10'W35.00'W32.10'W08.00'W57.30'W

(13 May

52.30'W46.90'W38.70'W28.70'W10.40'W07.00'W51.20'W47.60'W09.90'W06.40'W56.40'W40.60'W37.40'W32.90'W23.00'W15.80'W56.20'W52.60'W33.30'W13.50'W51.30'W47.80'W47.10'W

Distance(miles)

1910.61911.01921.11923.81936.11936.51938.31942.71951.61953.21955.11963.01964.21967.81969.61974.71977.91978.81981.01981.81984.01984.0

1975)

1984.01984.01986.61991.01993.01994.11995.11995.1

1975)

1995.11995.11997.82006.12008.52028.32037.1

L975>

2041.22045.62052.32060.52075.62078.42091.32094.32125.22128.12136.32149.32151.92155.62163.82169.72185.82188.72204.62220.82239.12242.02243.9

Speed(knots)

9.09.09.09.09.09.29.08.99.48.98.99.67.16.76.76.86.88.75.65.67.20.0

0.76.86.89.05.85.97.50.0

0.86.78.68.38.58.58.8

8.88.89.18.7

8.48.88.98.5

8.58.5

8.37.98.58.18.4

8.88.98.88.78.79.18.79.1

Course(degrees)

100888890

100143

9093

14593596365612515

210

198199202

0

219222028

219204210

0

95269270268268270272

272

270271270270269270270269266266266267268

268270270269268267260

342260

1174


TABLE 1 - Continued TABLE 1 - Continued

Time

000002800480208024803040320035404400450051006520710074508350842101210431142114413301336135514171540171017522146221022302342

000000

010202420246031503200402043205500711073607480808083508440844

173617361749180219502138223023002348

0000008003001340218

Latitude

34°34°34°34°34°34°34°34°34°34°34°34°34°34°34°34°34°34°34°34°34°34°34=34°34°35°35°35°35°35°35°

35°35°35°35°35°35°35°35°35°35°35°35°35°35°35°35°35°

35°35°35°35°35°35°35°35°35°

35°35°35°35°35°

47.90'N47.40'N47.10'N46.30'N46.00'N46.10'N46.20'N46.70'N47.60'N47.70'N47.90'N49.70'N50.00'N50.40'N50.60'N50.60'N50.30'N50.00'N52.70'N52.80'N56.80'N57.00'N57.40'N57.80'N59.60'N01.20'N01.50'N02.20'N02.50'N02.60'N03.80'N

04.20'N04.20'N05.70'N07.60'N07.60'N07.90'N07.90'N08.50'N08.80'N09.90'N10.70'N10.40'N10.30'N10.30'N09.80'N09.70'N09.70'N

09.70'N09.70'N10.00'N10.40'N14.90'N19.10'N20.80'N22.30'N24.30'N

24.80'N25.20'N26.20'N29.50'N31.80'N

Longitude

26°26°26°26°26°26°26°25°25°25°25°25°25°25°25°25°24°24°24°24°24°24°24°24°24°23°23°23°23°22°22°

22°22°22°22°22°22°22°22°22°21°21°21°21°21°21°21°21°

21°21°21°21°21°22°22°22°22°

22°22°22°22°22°

(14 May

41.30'W36.20'W32.60'W17.70'W10.10'W07.00'W04.00^57.60^49.70'W48.00'W44.10^25.10'W21.70'W15.10'W05.70'W04.4 0'W49.10^44.50'W36.20'W35.90'W20.70'W19.8CW16.70'W14.40'W01.00'W46.80'W40.10'W04.60'W00.80'W57.70'W46.50'W

(15 May

43.90^43.9CW34.30'W19.80^19.20^14.60^13.80'W07.20'W02.60^5 0.5 0'W38.10^34.20'W32.8CW30.10^26.60^25.60'W25.60'W

(16 May

25.60'W25.60'W27.1CW29.40^46.50'W05.90'W13.00'W20.00'W28.30'W

(17 May

30.50'W31.90'W35.60'W46.30'W53.30'W

Distance(miles)

1975)

2248.72252.92255.92268.22274.52277.02279.52284.72291.32292.72295.92311.62314.42319.82327.52328.62341.22345.02352.32352.52365.62366.42369.02370.92382.02393.82399.32428.32431.52434.02443.2

1975)

2445.42445.42453.42465.42465.92469.72470.32475.82479.52489.52499.72502.82504.02506.22509.12509.92509.0

1975)

2509.92509.92511.22513.12528.62544.22550.22556.12563.2

1975)

2565.02566.22569.42578.72584.9

Speed(knots)

9.18.99.29.49.49.39.38.58.59.69.29.39.39.39.38.47.47.57.47.48.18.15.18.17.87.87.57.87.77.77.2

7.77.77.27.27.87.87-87.57.77.67.55.86.66.55.36.70.0

1.05.88.88.68.78.68.88.89.2

9.28.78.78.48.7

Course(degrees)

263264266268272272276278275274277277275271268269266292288288287279280279278273271276272277281

281281279275274272276275276274265265269261262260

0

2217877737474767373

7372696867

Time

032403540404042405200600064008101102112011401248130813181336140614141429143014411441

0455045505090558073008521005111011171205121012191257132413381422145415261608'173018062038213021422218224123102330

00000300042010002460250033207500834

08570918

1250

Latitude

35°35°35°35°35°35°35°35°35°35°35°35°35°35°35°35°35°35°35°35°35°

35°35°35°36°36°36°36°36°36°36°36°36°36°36°36°37°37°37°37°37°37°37°38°38°38°38°38°38°

38°38°38°38°38°38°38°39°39°

39°39°

41°

35.60'N37.20'N37.70'N38.70'N41.60'N43.10'N44.70'N46.00'N50.20'N50.60'N50.90'N51.70'N51.90'N52.00'N52.00'N52.30'N52.30'N54.50'N54.60'N55.70'N55.70'N

55.70'N55.70'N56.70'N01.40'N10.20'N20.20'N30.10'N39.10'N40.00'N46.10'N46.80'N47.90'N52.10'N55.70'N57.60'N03.30'N07.50'N11.70'N17.30'N28.30'N33.10'N53.60'N00.30'N01.90'N06.80'N09.80'N13.70'N16.30'N

20.50'N24.60'N26.30'N28.90'N44.00'N44.60'N50.70'N44.60'N53.60'N

56.80'N59.50'N

34.00'N

Longitude

23°23°23°23°23°23°23°23°24°24°24°24°24°24°24°25°25°25°25°25°25°

25°25°25°25°25°25°25°25°25°25°25°25°25°25°25°25°25°25°25°25°25°25°25°25°25°25°25°25°

25°25°25°25°25°25°25°25°25°

25°25°

28°

04.10'W09.10'W10.80'W14.20'W24.40'W31.90'W39.40'W57.00'W30.20'W33.60'W37.40'W50.30'W54.30'W56.10'W59.30'W04.70'W06.40'W06.50'W06.50'W07.00'W07.00'W

(19 May

07.00'W07.00'W08 .30^14.60^26.10'W32.60'W35.40^37.50^37.80^40 .30^40 .60^41.30'W45.lOW45.6CW45.30^44.30^44 .20^44.50'W44.90^46.50'W46 .90^46.70'W46.40^46.30'W45 .80^46.50'W45.90^45 .50^

(20 May

45.00'W44.50'W44.50'W44.40'W44.50'W44.50'W44.6 0'W43.80'W45.30'W

47.80'W5 0.7 0'W

(21 May

45.80'W

Distance(miles)

2594.42598.82600.32603.22612.02618.32624.62638.92666.22668.92672.02682.52685.82687.22689.92694.22695.62697.82698.02699.12699.1

1975)

2699.12699.12700.62707.52720.32731.62741.82750.92751.92758.32759.02760.22765.42769.12770.92776.72780.92785.12790.82801.82806.62827.12833.82835.42840.32843.42847.32849.9

1975)

2854.12858.32859.92862.52877.62878.22884.32938.22947.3

2951.02954.6

1975)

3117.4

Speed(knots)

8.88.88.89.49.49.59.59.59.39.39.39.78.78.78.7

10.68.98.96.16.70.0

1.36.38.58.38.38.48.48.18.18.18.28.28.08.17.97.97.98.18.18.18.17.87.88.18.18.17.98.4

8.48.48.78.58.78.7

12.512.49.7

10.15.9

3.3

Course(degrees)

68717071767585818284868685908691

16

2010

0

2114847472813101618162935

7352352359

3373

360358356356

10353353355

355359358

0359

1359

732

3954

113

1175

O

43°N

40°

35°

-

-

i i I •

15 April '75

1

19 April '75

SITE 372 W

\

116 April '75

\

1 i 1 1

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25 April '75

s.

\ 18 April '75

•S ITE 371

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26 April '751 J>-

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27 Apr,, -75 2 9 A p r j , , ? 5

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30 April '75r\

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SITE 374

4 M

1 |

May '75/

ay '75

1

5 May '75

SITE 377 • *

1 i

17 May

15 May

1

1

19 May"75

'75

1 ' '

21 May '75\

;

;

3d6 ^

I

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•E378

14 May '75

lay '75

1 1 | 1

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7 5

13 May '75

• • , . | | f l.it.

7 May '75

1 1 1

12 May '75

^i SITE 376% SITE 37510 May '75

10° 15° 20" 25° 30° 35°E

Figure 1.


N. MILES60 100 150 200 250 300 350 400 450 500 550 600 604

i r i ri r

500 550 600 60450 100 150 200 260 300

Figure 2.

Figure 2 — Continued

1177

G. W. BODE

1250 1300 1350

~i i r ~i r1600 1650 1700 1750 1800 1804

i o

I I

1750 1800 18041250 1300 1350 1400 1450 1500 1550 1600 1650 1700


i 1 i r i π

1800 1850 1900 1950 2000


1178


500

- 1000

2400 2450 2500 2550 2600 2800 2850 2900 2950 3000 3004


N. MILES

3000 3050 3100 3150 3200 3250 3300 3350 3400 3450 3500 3550 3600 3604

500

a500

-1000

i i i I

-

- v/-^ ^ —

3000 3050 3100 3150 3200 3250

N. MILES

3300 3350 3400 3450 3500 3550 3600 3604

-

I I I

I

r

I

28 M

ay 7

5

I i ' ' i i I m u m i I I il I I I I I


1179

G. W. BODE

-500

-1000

3 6 0 0 3 6 5 0

4000

S

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I I II I I

fe S :

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1180

Figure 3

OOto

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2000Z15 Apr.'75

0000Z16 Apr. '75

0400Z16 Apr.'75

t -3

SITE 371

0800Z16 Apr '75

0800Z18 Apr. '75


1200Z18 Apr.'75

1600Z18 Apr.'75

- 6

SITE 372

2000Z18 Apr.'75

0 0

0800Z25 Apr. '75


0400Z25 Apr. '75 25 Apr. '75

1200Z25 Apr. '75

1600Z25 Apr. '75

Owo•oX><CΛ

n>r1

o

rZo

I l l l i I - 0 o

1600Z26 Apr. '75

2000Z26 Apr. '75


SITE 373

OOOOZ27 Apr. '75

0400Z27 Apr. '75

1200Z29 Apr. '75

. - 51OOOZ30 Apr. '75

1600Z29 Apr. '75


oo- 2

1200Z30 Apr. '75

1600Z30 Apr. '75

2000Z30 Apr. '75

—3

a

SITE 374

0200Z1 May '75


1200Z4 May '75

T1600Z4 May '75

2000Z4 May '75

OOOOZ5 May '75

0400Z5 May '75

- 2

0800Z5 May '75

1200Z5 May '75

- 5

- 6



1600Z6 May '75

2000Z6 May '75

1ooooz7 May

S'75

-60400Z7 May '75

SITE 376 12 km NESITE 375 OF SITE 375

0800Z7 May '75

1200Z7 May '75

2000Z12 May'75


o

0400Z13 May'75

0800Z13 May'75

- 2

1200Z13 May'75

1600Z13 May'75

2000Z13 May'75

OOOOZ14 May'75

Figure 3 —Continued



0500Z15 May'75

0700Z15 May'75

Figure 3 - Continued

ooooz17 May'75

0330Z17 May'75

O>

JOO

SITE 378

0400Z17 May '75

0800Z17 May'75

1200Z17 May'75

0600Z19 May'75

- 3

- 4

Q

0800Z19 May '75


1200Z19 May'75

1600Z19 May '75

- 32000Z19 May'75

Figure 3 - Continued

Documents

Deep Sea Drilling Project Initial Reports Volume 42, Part 1