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
GEOPHYSICAL PROFILING
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
.' '
25 April '75
s.
\ 18 April '75
•S ITE 371
i i
' ' 1
26 April '751 J>-
V. ^>^^
I I 1
I 1 • I |
27 Apr,, -75 2 9 A p r j , , ? 5
^ ^ SITE 373 ^ s .
>
i i I I 1
i i i
30 April '75r\
\t 1
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
y— 20 May '
•E378
14 May '75
lay '75
1 1 | 1
r TIstanbul
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.
GEOPHYSICAL PROFILING
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
Figure 2 — Continued
i 1 i r i π
1800 1850 1900 1950 2000
Figure 2 — Continued
1178
GEOPHYSICAL PROFILING
500
- 1000
2400 2450 2500 2550 2600 2800 2850 2900 2950 3000 3004
Figure 2 — Continued
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
Figure 2 — Continued
1179
G. W. BODE
-500
-1000
3 6 0 0 3 6 5 0
4000
S
I I !i I t
I I II I I
fe S :
_ l I L J I I I ll l l I 1 I l l I i l l
Figure 2 — Continued
1180
Figure 3
OOto
O
2000Z15 Apr.'75
0000Z16 Apr. '75
0400Z16 Apr.'75
t -3
SITE 371
0800Z16 Apr '75
0800Z18 Apr. '75
Figure 3 — Continued
1200Z18 Apr.'75
1600Z18 Apr.'75
- 6
SITE 372
2000Z18 Apr.'75
0 0
0800Z25 Apr. '75
Figure 3 — Continued
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
Figure 3 — Continued
SITE 373
OOOOZ27 Apr. '75
0400Z27 Apr. '75
1200Z29 Apr. '75
. - 51OOOZ30 Apr. '75
1600Z29 Apr. '75
Figure 3 — Continued
oo- 2
1200Z30 Apr. '75
1600Z30 Apr. '75
2000Z30 Apr. '75
—3
a
SITE 374
0200Z1 May '75
Figure 3 — Continued
1200Z4 May '75
T1600Z4 May '75
2000Z4 May '75
OOOOZ5 May '75
0400Z5 May '75
- 2
0800Z5 May '75
1200Z5 May '75
- 5
- 6
Figure 3 — Continued
Figure 3 — Continued
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
Figure 3 — Continued
o
0400Z13 May'75
0800Z13 May'75
- 2
1200Z13 May'75
1600Z13 May'75
2000Z13 May'75
OOOOZ14 May'75
Figure 3 —Continued
Figure 3 — Continued
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
Figure 3 — Continued
1200Z19 May'75
1600Z19 May '75
- 32000Z19 May'75
Figure 3 - Continued