Technical Note 20/4


LEG 173 PROSPECTUS

Table 1. Proposed Site Information and Drilling Strategy***


SITE:  Iberia-7A	PRIORITY:	1		POSITION: 40°42'N, 11°48'W
WATER DEPTH:5150 m	SEDIMENT THICKNESS: 920 m	TOTAL PENETRATION: 1020 m
SEISMIC COVERAGE:Sonne-75 Line 2, CDP730; Line CAM 134

Objectives:  Sample acoustic basement high on westernmost fault block; refine history of turbidite/contourite sedimentation; measure heat flow

Drilling Program: Wash down and RCB

Logging and Downhole Operations:  Quad, GLT, FMS

Nature of Rock Anticipated: Nannofossil clay, clay, claystone, siltstone and fine sandstone, ooze and chalk; mid/lower continental crust or serpentinized peridotite


SITE: Iberia-8A		PRIORITY:	1		POSITION:  40°42'N, 11°18'W
WATER DEPTH: 4830 m	SEDIMENT THICKNESS: 1050 m	TOTAL PENETRATION:1150 m 
SEISMIC COVERAGE:  Lusigal-12, SP4580; Line CAM 145

Objectives:Sample acoustic basement high (continental crust overlain by syn-rift sediments); refine history of turbidite/contourite sedimentation; measure heat flow

Drilling Program: Wash down and RCB

Logging and Downhole Operations:  Quad, GLT, FMS

Nature of Rock Anticipated: Nannofossil clay, clay, claystone, siltstone and fine sandstone, ooze and chalk; mid/lower continental crust possibly overlain by tilted syn-rift sediments 

OR
SITE: Site 901* PRIORITY: 1 POSITION: 40°42'N, 11°3.6'W WATER DEPTH: 4720 m SEDIMENT THICKNESS: 600 m TOTAL PENETRATION: 700 m SEISMIC COVERAGE: Lusigal Line 12 SP4938 Objectives: Continue Site 901 to basement at east end of OCT to sample and date the pre-rift sediments; refine lithospheric extension rift model; determine sedimentation and subsidence history, measure heat flow Drilling Program: Wash down and RCB to 100 m or bit destruction Logging and Downhole Operations: Quad, GLT, FMS Nature of Rock Anticipated:Nannofossil clay, silt, sandstone, shallow-water sandstones and carbonates; continental crust

SITE: Iberia-9A*	PRIORITY:			POSITION: 40°42'N, 11°36'W
WATER DEPTH: 5150 m	SEDIMENT THICKNESS: 1100 m	TOTAL PENETRATION: 1150 m 
SEISMIC COVERAGE: Sonne-75 Line 21; Lusigal Line 12, SP4020 (-9A), SP4035 (-9B)

Objectives: Drill through the detachment fault

Drilling Program: Wash down and RCB

Logging and Downhole Operations:  Quad, GLT, FMS

Nature of Rock Anticipated: Nannofossil clay, clay, claystone, siltstone and fine sandstone, ooze and chalk; continental crust or gabbro

OR
SITE: Iberia-9B PRIORITY: 1 POSITION:40°42'N, 11°33'W WATER DEPTH: 5040 m SEDIMENT THICKNESS: 1500 m TOTAL PENETRATION: 1550 m SEISMIC COVERAGE: Sonne-75 Line 21; Lusigal Line 12, SP4020 (-9A), SP4035 (-9B); Line CAM 136 Objectives: Drill through detachment fault Drilling Program: Wash down and RCB Logging and Downhole Operations: Quad, GLT, FMS Nature of Rock Anticipated:Nannofossil clay, clay, claystone, siltstone and fine sandstone, ooze and chalk; continental crust or gabbro

SITE: Galice-1A		PRIORITY:	2		POSITION:  42°42'N, 12°48'W
WATER DEPTH: 4500 m	SEDIMENT THICKNESS: 600 m	TOTAL PENETRATION:   700 m
SEISMIC COVERAGE: Lusigal 6, GP03

Objectives: Exploratory hole above S' reflector 

Drilling Program: Wash down through 600 m of sediment and RCB 100 m of basement

Logging and Downhole Operations:  Quad, GLT, FMS

Nature of Rock Anticipated: Pelagic clay, sand, silt, clay turbidites, chalk, continental crust


SITE: Iberia-10A	PRIORITY:	2		POSITION: 40°48'N, 12°42'W
WATER DEPTH: 5500 m	SEDIMENT THICKNESS: 830 m	TOTAL PENETRATION:  930 m
SEISMIC COVERAGE: Sonne-75 Line 16 SP310; Discovery-161 day 234

Objectives: Sample oceanic basement west of known peridotite; refine history of turbidite sedimentation; measure heat flow.e

Drilling Program:  Wash down and RCB to 100 m or bit destruction

Logging and Downhole Operations:   Quad, GLT, FMS

Nature of Rock Anticipated: Nannofossil clay, clay, claystone, fine sand, silt, claystone turbidites, basalt


* First Priority Sites

To Leg 174A

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