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