Deep Sea Drilling Project Initial Reports Volume 1 · 2007. 5. 14. · The term Sigsbee Abyssal Plain will be used in this report to describe all of the deep floor of the Sigsbee

INTRODUCTION1

M. Ewing & J. L. WorzelLamont-Doherty Geological Observatory, Palisades, New York

andC. A. Burk

Mobil Oil Corporation, Princeton, New Jersey

The Glomar Challenger departed Orange, Texas, onJuly 20, 1968, completed acceptance trials on August11,1968, and concluded the work of Leg 1 in Hoboken,New Jersey, on September 23, 1968. During thiscampaign, eleven holes were drilled at seven differ-ent sites. As a result of the pioneering characterof this work, many new records for drilling in deepwater from a dynamically positioned vessel were estab-lished. These include: drilling in a water depth of5354 meters (17;567 feet), use of a drill pipe length of5650 meters (18,523 feet), and penetration beneaththe sea fltfor of 770 meters (2528 feet). Scientificachievements of Leg 1 include the recovery of theoldest rocks (uppermost Jurassic) yet found in thedeep ocean, discovery of petroleum and typical saltdome cap rock in the deep ocean, and demonstrationof the important role of turbidites and radiolarianchert and hard limestone strata in deep-sea sedimentarydeposits.

The planned drilling and coring operations of Leg 1were severely curtailed by a decrease of two weeks inthe time available, owing to a delay in acceptance ofthe vessel and an advance of the termination date inanticipation of labor trouble in the Port of New York.Despite this misfortune, three important areas wereinvestigated-the deep basin of the Gulf of Mexico, the"Horizon A outcrop area" east of San Salvador Island,where the oldest sediments were expected, and theBermuda Rise. The locations of the sites investigatedduring Leg 1 and a summary of the drilling resultsobtained are given in Figure 1 and Table 1.

SUMMARY OF DRILLING OPERATIONSAND RESULTS

Holel

Site: This is in the Gulf of Mexico on the SigsbeeAbyssal Plain2 near the foot of the Sigsbee Scarp,which is a major break in topography between thecontinental slope and the abyssal plain.

Objectives: They were to study the stratigraphy andlithology of deeper sediments of Sigsbee Abyssal Plainnear the Sigsbee Scarp. This hole was drilled mainly toobtain operational practice in deep drilling and coring.

Cores Taken From Hole 1

CoreNo.

123456789

CoreNo.

123456789

Drül String (ft)

9789-981910,274-10,30410,785-10,81510,850-10,88010,880-10,91011,560-11,57411,574-11,60411,760-11,79011,790-11,820

Drill String(meters)

2983.7-2992.83131.5-3140.73287.3-3296.43307.1-3316.23316.2-3325.43523.5-3527.83527.8-3536.93584.5-3593.63593.6-3602.7

Penetration (ft)

497-527982-1012

1493-15231558-15881588-16182268-22822282-23122468-24982498-2528

Penetration(meters)

151.5-160.6299.3-308.5455.1-464.2474.9-484.0484.0-493.2691.3-695.6695.6-704.7752.3-761.4761.4-770.5

CoreRecovered

(ft)

3015708

14303030

164

CoreRecovered(meters)

9.14.62.10.02.44.39.19.19.1

49.8

Results: The whole section sampled was Pleistocenemudstone rich in detrital carbonates. Pelagic fossils areextremely scarce in this great flood of Pleistocene tur-bidites.

Lamont-Doherty Geological Observatory of Columbia Uni-versity contribution No. 1362.The term Sigsbee Abyssal Plain will be used in this report todescribe all of the deep floor of the Sigsbee Basin.

Three logs were made in Hole 1: an in-pipe gamma-ray/neutron log, an open hole gamma-ray and qualita-tive gamma-gamma (density) log, and a conventionalopen-hole resistivity log.

TABLE 1Summary of Holes Drilled on Leg 1

Hole PositionNo. Lat. Long. Dates of Drilling

Water Water Penetration Penetration No.Depth Depth (Subbottom (Subbottom ofFeet Meters Feet) Meters) Cores

Footage MetersFootage Meters of Core of CoreCored Cored Recovered Recovered

1 25°51.5'N 92°11.0'W

2 23°27.3'N 92°35.2'W

3 23°0r.0'N 92°01.4'W

4 24°28.68'N 73°47.52'W

4A 24°28.68'N 73°47.52'W

5 24°43.59'N 73°38.46'W

5A 24°43.59'N 73°38.46'W

6 30°50.39'N 67°38.86'W

6A* 30°50.39'N 67°38.86'W

7 30°08.04'N 68°17.80'W

7A 30°08.04'N 68°17.8θ'W

August 12-16

August 19-21

August 21-23

August 29-31

September 1-2

September 4-5

September 6-10

September 12-14

September 14-15

September 16-17

September 18-19

9275

11,720

12,294

17,452

17,452

17,589

17,589

16,815

16,815

17,013

17,013

2827.0

3572.3

3747.2

5319.4

5319.4

5361.1

5361.1

5125.2

5125.2

5185.6

5185.6

2528

472

2059

849

680

263

914

842

78

775

972

770.5

143.9

627.6

258.8

207.3

80.2

278.6

256.6

23.8

236.2

296.3

9

6

11

5

3

3

7

6

1

2

3

254

117

320

190

61

90

129

153

30

32

65

77.4

35.7

97.5

57.9

18.6

27.4

39.3

46.6

9.1

9.8

19.8

164.00

43.50

154.00

48.00

19.00

21.00

5.75

93.00

28.00

32.00

15.00

50.0

13.2

46.9

14.6

5.8

6.4

1.7

28.4

8.5

9.8

4.6

* Did not involve a trip to surface-merely a bottom surface core taken while coming out of Hole 6.

ATLANTICOCEAN

BERMUDA

Figure 1. Deep-Sea Drilling Project-Leg 1-12 August to 23 September 1968.t-/1

Hole 2

Site: This hole is on one of the Sigsbee Knolls in thecentral part of the Gulf of Mexico. The Sigsbee Knolls,of which there are now more than 150 recorded, areknown to extend along a southwestern trend to theTabasco-Campeche Saline Basin in Mexico. This site isnear the northeastern extremity of the belt.

This knoll, named by the shipboard scientific staff ofthe "Challenger Knoll," was chosen on the basis ofprior surveys by Lamont-Doherty Geological Observa-tory because a sediment cover at about 450 to 500 feetwas observed over the piercement material.Objectives: The objectives of drilling here were tosample what was believed to be diapiric material underthe knoll and to establish a pelagic Pleistocene strati-graphic sequence.

Cores Recovered From Hole 2Core

Recovered(ft)

CoreNo. Drill String (ft) Penetration (ft)

123456

11,817-11,84711,942-11,97211,972-11,98612,086-12,11212,200-12,20712,215-12,225

64-94189-219219-233333-359447-454462472

11.04.0

12.09.06.51.0

43.5

CoreNo.


Penetration(meters)

CoreRecovered

(meters)

3601.8-3611.03639.9-3649.13649.1-3653.33683.8-3691.73718.6-3720.73723.1-3726.2

19.5-28.757.6-66.866.8-71.0

101.5-109.4136.3-138.4140.8-143.9

3.41.23.72.72.00.3

13.3

Results: Below 136 meters of Pleistocene and Pliocenepelagic sediments, a typical cap rock with gypsum,sulfur, limestone, oil, gas and traces of anhydrite wasfound. The presence of jdeep salt beds, probably Juras-sic in age, is strongly suggested. This hole was aban-doned and plugged, since there were rigid instructionsto avoid any possibility of an uncontrolled flow of oil.

Hole 3

Site: This is on the Sigsbee Abyssal Plain near theChallenger Knoll.Objectives: This site was drilled to obtain samples inthe vicinity of the knoll of the sequence of normal

basin sediments—for comparison with the sectionfound on the knoll—and for identification of theextensive seismic reflectors of this basin.

CoreNo.


Recovered(ft)Drill String (ft) Penetration (ft)

123456789

1011

12,409-12,43912,444-12,47412,984-13,01413,014-13,04513,377-13,40713,410-13,44013,577-13,60713,736-13,76614,079-14,10914,327-14,35714,362-14,387

82-112117-147657-687687-718

1050-10801083-11131250-12801409-14391752-17822000-20302035-2060

101354

2410202830

64

154

CoreNo.


Penetration(meters)


1234567891011

37823792395739664077408741384186429143664377

3-3791.49-3802.15-3966.77-3976.13-4086.54-4096.53-4147.47-4195.93-4300.49-4376.05-4385.2

25.0-34.135.7-44.8

200.3-209.4209.4-218.9320.0-329.2330.1-339.2381.0-390.1429.5-438.6534.0-543.2609.6-618.7620.3-627.9

3.14.01.51.27.33.16.18.59.11.81.2

46.9

Results: Pleistocene sediments were brown to gray siltyclays from the Mississippi Cone over a northeasterly-dipping calcareous section interbedded with calcareousturbidites. These were overly conformably, thick,carbonate Pliocene turbidites. The Miocene sedimentsto 2060 feet were mudstones rich in volcanics. Thehole was abandoned on the basis of an order stat-ing that 2000 feet penetration was the maximumpermitted.

Hole 4

Site: Hole 4 is sited east of the Bahamas within theoutcrop of the seismic reflecting Horizon A, at a placewhere Horizon 0 appears to be about 50 feet andHorizon B about 1200 to 1400 feet subbottom-supposedly, well within the reach of the GlomarChallenger drill.

6

Objectives: A major objective of the JOIDES programis to locate and recover the oldest sediments in theocean basins. The primary objective of Site 4 was toobtain a sample of Horizon ß and Horizon B.

CoreNo.



1234--5

17,485-17,51517,827-17,85717,924-17,95418,111-18,14118,238-18,26818,268-18,29218,304-18,334

0-30342-372439469626-656753-783783-807819-849

30755

No recoveryNo recovery

148

CoreNo.


Penetration(meters)

CoreRecovered

(meters)

1234--5

5329.4-5338.65433.7.5442.85463.2-5472.45520.2-5529.45558.9-5568.15568.1-5575.45579.1-5588.2

0-9.1104.2-113.4133.8-143.0190.8-200.0229.5-238.7238.7-246.0249.6-258.8

9.12.11.51.5

0.314.5

Results: Below about 600 feet penetration, the drillwith increasing frequency encountered resistant andabrasive chert beds which wore out the bit, andcaused operations at this hole to be terminated. Theroller bit used here was completely destroyed by thechert.

Hole 4A

Site: This is the same as Hole 4.Objectives: These were the same as for Hole 4.

CoreNo.

Cores Recovered From Hole 4ACore


1 17,724-17,7542 17,860-17,8903 18,164-18,165

239-269 15375-405 4679-680 Pieces of chert

19

CoreNo.


Penetration(meters)


5402.3-5411.45443.7.5452.95536.4-5536.7

72.9-82.0114.3-123.4207.0-207.3

4.61.2

Results: A drag bit was used in the hope that it mightdo better in the chert than the roller bit. Hole 4Apassed through the same succession as Hole 4, andencountered the same hard abrasive cherts below 600feet. At a depth of approximately 680 feet, the corebarrel jammed and operations at this site were curtailed.After the pipe was pulled, it was found that the dragbit had been destroyed by the chert. These cores andthose from Hole 5 may be discussed as a unit.

Hole 5

Site: Site 5, a short distance from Site 4, was chosenat the locality where Neocomian sediments, the oldestrecovered in the deep ocean so far, had been recoveredin piston core samples by Lamont-Doherty GeologicalObservatory. A smooth seismic reflector called HorizonB, which is normally deeply buried, was believed to beexposed at this locality; but, all of the beds are foldedand distorted here, so the exact setting will not beknown until a detailed site survey can be made.Objectives: These were to obtain samples of the oldestrocks and sediments yet recovered from the oceans.


Recovered(ft)


17,600-17,63017,702-17,73217,833-17,858

0-30102-132233-263

- 144

2\

CoreNo.


Penetration(meters)


5364.5-5373.65395.6-5404.75435.5-5443.1

0-9.131.1-40.271.0-80.2

4.31.20.96.4

Results: A diamond bit was used here. The drill bitplugged at 260 feet of penetration, and drilling andcoring were terminated.

Hole 5A

Site: This is the same as Hole 5.Objectives: These were the same as for Hole 5.

7

Cores Recovered From Hole 5AUsing Same Diamond Bit as for Hole 5

CoreCore RecoveredNo. Drill String (ft) Penetration (ft) (ft)

1234567

17,880-17,90017,921-17,95018,076-18,10618,206-18,20718,357-18,36218,373-18,40318,500-18,514

280-300321-323476-506606-607757-762773-803900-914

0.252.000.501.001.00*0.500.505.75

*cobble

CoreNo.


Penetration(meters)


Results: Cores of coccolith ooze, cherty radiolarianmudstones, and gray and white chalk were recovered.Except for the topmost core, they are barren of foram-inifera, but nannofossils indicate that they range in agefrom Cenomanian (upper cores) to Tithonian (UpperJurassic, lowermost core). Layer B was not reached.

Once again the chert layers brought drilling to a halt.The plan had been to take an eighth core, and then tolog the hole. However, while this was being attempted,the sand line parted and that plan was abandoned.When the diamond bit was recovered, it was found tobe completely worn down, and with the edges of thecenter hole peened over.

At Sites 4 and 5, Tithonian sediments of open oceansfacies were reached. The considerable thickness ofunderlying sediments shown by the seismic surveyssuggests that this sedimentary regime had prevailed atleast back to early Jurassic time. Turbidites, abundantRadiolaria, mudstones and cherts from late Jurassic tolate Cretaceous are significant when compared to theradiolarian fauna of the same age found earlier in theCaribbean in Lamont-Doherty piston core samples, andthen mentioned as suggesting a connection betweenthe Caribbean and the Pacific. The cherts and hardlimestones found in the Horizon A outcrop area wereclear signals that deep-sea drilling might involve pene-tration of very resistant beds.

Hole 6

Site: This hole was drilled on the flank of the BermudaRise in an area where the profiler records indicatedthat Horizons A and ß would be within reach of thedrill. The site was far enough above the HatterasAbyssal Plain that younger turbidites were not expected.Piston cores from the general area had indicated thatgood pelagic faunas might be obtained despite thedepth of water.Objectives: The objectives of drilling this hole were:to document the faunal changes across the Mesozoic-Cenozoic boundary, to determine the natures of Hori-zons A and |3, and to examine Mesozoic-Cenozoicpelagic sedimentation.

Cores Recovered From Hole 6Using Christensen Drag Bit

1234567

5449.8-5455.95462.3-5471.25509.6-5518.75549.2-5549.55595.2-5596.75600.1-5609.25638.8-5643.1

85.3-91.497.8-98.5

145 1-154.2184.7-185.0230.7-232.3235.6-244.8274.3-278.6

0.080.610.150.300.300.150.151.74

123456

CoreNo. Drill Strings(ft) Penetration (ft)

CoreRecovered

(ft)

16,979-17,00917,344-17,37417,470-17,50017,597-17,62717,654-17,66217,662-17,687

134-164499-529625-655752-782809-817817-842

1830151479

93

CoreNo.


Penetration(meters)


1234

6

5175.2-5184.35286.5-5295.65324.9-5334.05363.6-5372.75380.9-5383.45383.4-5391.0

40.8-50.0152.1-161.2190.5-199.6229.2-238.4246.6-249.0249.0-256.6

5.59.14.64.32.12.7

28.3

Results: The drillers reported surprisingly hard drillingfor the first 20 feet, after which the formations weresoft. The first core was 134 to 164 feet of barren deep-sea clay. After penetration of the barren red clay overmuds, clays and turbidites containing cocct>liths, dia-toms and Radiolaria totaling 842 feet were obtained.Progress was then stopped; the bit was destroyed byradiolarian cherts.

Hole 6A

Site: This is the same as Hole 6.Objecitves: After the abandonment of Hole 6, this holewas drilled, without a trip to the surface to test a veryhard layer that had been reported by the drillers asforming the first 20 feet of the section at Hole 6.Results: The drill pipe was pushed into the bottomwithout rotation to 50 feet of penetration without

8

encountering any resistant strata. Then a core was cutfrom 50 to 78 feet. It was found to consist of browndeep-sea clay. The nature of the topmost formation atHole 6 remains an even greater mystery than before.

Hole 7Site: This is about 50 miles from Site 6, on the flankof the Bermuda Rise in an area where it was hopedthat Horizon ß could be sampled, because the intervalbetween Horizons A and ß appeared to be less thannormal.Objectives: It was hoped that Horizon ß could bereached and penetrated to recover samples of the under-lying sediment.

Cores Recovered From Hole 7Using a Diamond Bit

CoreNo. Drill String;(ft) Penetration (ft)

CoreRecovered

(ft)

17,033-17,06317,803-17,806

0-30773-775

30

__32

CoreNo.


Penetration(meters)

CoreRecovered

(meters)

5191.7-5200.85426.4-5427.3

0-9.1235.6-236.2

9.10.69.7

Results: A brown deep-sea clay was encountered atsurface as at Site 6. Below this was the expectedmid-Eocene cherty turbidite section. The hole wasterminated in pre-mid-Eocene, but otherwise undated,deep-sea clays. Drilling and coring operations wereterminated because of damage to the core barrel whenthe vessel was allowed to roll in the trough of a mod-erate swell. A trip to the surface was necessary toretrieve the core barrel and modify another one to fitthe same diamond bit. Core 7, Section 2, was a middleEocene turbidite with chert, similar to that found atSite 6.

Hole 7A

Site: This is the same as Hole 7.Objectives: These were the same as Hole 7—to try topenetrate the cherts and find the age of the sedimentbelow.

Cores Recovered From Hole 7AUsing Same Diamond Bit as for Hole 7


CoreRecovered

(ft)

123

17,905-17,91017,945-17,97517,975-18,005

872-877912-942942-972

078

15

CoreNo.


Penetration(meters)


5457.4-5459.05469.6-5478.85478.8-5487.9

265.8-267.3278.0-287.1287.1-296.3

0.02.12.44.5

Results: The hole penetrated the mid-Eocene chertyturbidites, after much time spent at a slow drilling rate.At Core 7A, Section 1, the diamond center bit, badlychamfered by chert, was replaced. Very slow progresscontinued until much softer formations were foundat 272 meters (902 feet) subbottom. Two cores be-tween 912 and 972 feet each yielded 30 feet of barrendeep-sea clays, considerably different in coloration andbanding than any seen before. Ages from early Ceno-zoic to late Cretaceous have been suggested on thebasis of extrapolation. The hole was abandoned atthis point on orders from the Captain, who favoreda safe margin of travel time to ensure arrival in portat a stated deadline.

REFERENCES

JOIDES, 1967. Deep-Sea Drilling Project. Bull. Am.Assoc. Petrol. Geologists. 51 (9), 1787.

1967. Deep-Sea Drilling Project. Am. Geo-phys. Union Trans. 48, 817.

1965. Ocean drilling on the continentalmargin. Science. 150 (3697), 709 (prepared by E. T.Bunce, K. O. Emery, R. D. Gerard, S. T. Knótt,L. Lidz, T. Saito, and J. Schlee).

Worzel, J. L., Leyden, R. and Ewing, M., 1968. Newlydiscovered diapirs in Gulf of Mexico. Bull. Am.Assoc. Petrol. Geologists. 52, 1194.

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Documents

Deep Sea Drilling Project Initial Reports Volume 1 · 2007. 5. 14. · The term Sigsbee Abyssal Plain will be used in this report to describe all of the deep floor of the Sigsbee