___________________ __________________
Dr. Jack Baldauf Dr. Carl Richter
Deputy Director Leg Project Manager
of Science Operations Science Services
ODP/TAMU ODP/TAMU

This publication was prepared by the Ocean Drilling Program, Texas A&M University, as an account of work performed under the international Ocean Drilling Program, which is managed by Joint Oceanographic Institutions, Inc., under contract with the National Science Foundation. Funding for the program is provided by the following agencies:

Australia/Canada/Chinese Taipei/Korea Consortium for Ocean Drilling
Deutsche Forschungsgemeinschaft (Federal Republic of Germany)
Institut Français de Recherche pour l'Exploitation de la Mer (France)
Ocean Research Institute of the University of Tokyo (Japan)
National Science Foundation (United States)
Natural Environment Research Council (United Kingdom)

European Science Foundation Consortium for the Ocean Drilling Program (Belgium, Denmark, Finland, Iceland, Italy, The Netherlands, Norway, Portugal, Spain, Sweden, and Switzerland)

Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the National Science Foundation, the participating agencies, Joint Oceanographic Institutions, Inc., Texas A&M University, or Texas A&M Research Foundation.

This Scientific Prospectus is based on precruise JOIDES panel discussions and scientific input from the designated Co-chief Scientists on behalf of the drilling proponents. The operational plans within reflect JOIDES Planning Committee and thematic panel priorities. During the course of the cruise, actual site operations may indicate to the Co-Chief Scientists and the Operations Manager that it would be scientifically or operationally advantageous to amend the plan detailed in this prospectus. It should be understood that any proposed changes to the plan presented here are contingent upon approval of the Director of the Ocean Drilling Program in consultation with the Science and Operations Committees (successors to the Planning Committee) and the Pollution Prevention and Safety Panel.

Technical Editor: Karen K. Graber

Three primary drilling sites and alternatives have been identified to achieve these objectives. The drilling strategy consists of the following:
1.Drill one primary site (Site PBS-2A) on the Prydz Bay continental shelf to core the stratigraphic interval between the deepest Paleogene glacial sediments recovered at Ocean Drilling Program (ODP) Site 742 and the shallowest Cretaceous coal-bearing sediments acquired at ODP Site 741 to date the onset of glaciation in Prydz Bay and assess late Mesozoic and early Cenozoic preglacial environments.
2.Drill one primary site (Site PDB-12B) on the continental rise to sample a section of drift deposits and underlying units that extend back to the earliest time (early Oligocene) when ice reached the continental shelf edge and caused a major change in sedimentation on the rise. Glacial events recorded here will be compared with those seen in slope and shelf drill sites, including those drilled during Leg 119.
3.Drill one primary site (Site PBF-6A) on the continental slope to recover a section through the Prydz Channel Fan that was built by sediment carried in the base of the Lambert Glacier when it advanced to the shelf. Cores from this site should record the number of times the East Antarctic Ice Sheet has expanded to the shelf edge since late Miocene time.

Alternative drilling strategies have been developed to fulfill the Leg 188 objectives in case ice conditions prevent access to preferred drilling areas. If time permits, the leg will acquire a high resolution Holocene environmental record by coring a section of biosiliceous Holocene sediments on the Mac Robertson Shelf west of Prydz Bay. This section should have a resolution comparable to ice cores and similar sediments cored in Palmer Deep during Leg 178.

To address these problems, the Scientific Committee for Antarctic Research supports the ANTOSTRAT committee, which has fostered the development of a series of Antarctic drilling proposals. Each proposal has been designed to address different aspects of Antarctic glacial history. Leg 178 scientists examined the glaciation history of the Antarctic Peninsula, which is covered by small ice masses that developed during the Neogene and respond rapidly to climate changes. Leg 188 is designed mainly to address the history of the East Antarctic Ice Sheet, which is long lived and responds relatively slowly to major climate events. In particular, Leg 188 results, in conjunction with the results of Leg 119, can provide insights into the state of the interior of East Antarctica (Fig. 2).

During some, but not all, Cenozoic glacial episodes, the Lambert Glacier advanced to various points on the shelf, prograding the shelf and building a large trough mouth fan that records these major advances since the late Miocene-middle Pliocene (Figs. 1B, 4). Interglacial sediments are probably preserved on the slope foresets; thus, the Prydz Channel Fan contains a measure of the major sediment pulses caused by peaks in Antarctic ice volume over the last 4-5 m.y.

The continental rise adjacent to Prydz Bay exhibits large sediment drifts deposited under the influence of turbidity currents from the continental shelf and deep currents in the Southern Ocean (Fig. 4). These drifts are a fine-grained distal equivalent to shelf and upper slope sediments and record fluctuations in the ratio of continent-derived terrigenous sediments to oceanic material and record the fluctuations of oceanic current activity (Fig. 5). The amount of terrigenous material rises strongly with major ice expansions so that interbedding of terrigenous-rich and biogenic-rich horizons tend to reflect glacial-interglacial cycles. The longevity of these drifts and the presence of seismic horizons that can be projected back to the continental slope and shelf mean that these drifts can provide a link between continental glaciation and changes in the ocean back through time to the Paleogene.

Regional Setting
Prydz Bay is a re-entrant in the East Antarctic coastline between 68°E and 78°E (Figs. 2, 4). The bay shape and glacier flow patterns reflect the underlying geological structures, the Lambert Graben and Prydz Bay Basin (Fedorov et al., 1982; Stagg, 1985). The Lambert Graben extends about 600 km inland, is as much as 200 km wide, and contains more than 5 km of sediment, based on magnetic and seismic refraction data (Fedorov et al., 1982). The Lambert Graben-Prydz Bay Basin fill consists of two lower sequences of parallel bedded units that onlap or are faulted against basement beneath the northwestern and southeastern sides of the bay (Fig. 6). These sequences were penetrated at Ocean Drilling Program (ODP) Sites 740 and 741 drilled during Leg 119 and consist of Cretaceous coal-bearing nonmarine sediments overlying nonmarine redbeds (Turner and Padley, 1991; Turner, 1991). Cenozoic sequences overlying the Cretaceous have foreset and topset beds that prograde the continental shelf (Cooper et al., 1991a, 1991b).

West of Prydz Bay, the Mac Robertson Shelf is a passive margin that probably formed during the Mesozoic. It is narrow compared to the Prydz Bay shelf and is rugged, having experienced erosion by glaciers during glacial episodes and by iceberg scouring and geostrophic currents during interglacials (Harris and O'Brien, 1996).

Sedimentary Environments
The Prydz Bay continental slope and rise are underlain by thick (more than 6000 m) post lower Cretaceous sediments. Some of the sediment drifts in Prydz Bay are elongated ridges aligned along the margins of deep channels, others have no clear correlation with channels, but all of them are elongate approximately orthogonal to the continental margin (Fig. 4). The features and seismic patterns of sediment drifts suggest that they have been basically deposited as a result of the interaction of downslope mass flow and strong bottom (contour) currents (Fig. 5). The drifts are composed of a mixture of sediment derived from the continent and biogenic material. Drilling of drifts beneath the continental rise during ODP Leg 178 showed that they preserve alternating clastic-rich and biogenic-rich intervals that reflect alternations of glacial and interglacial conditions. Such records can be compared to the proximal records of the continental shelf and upper slope to understand the relationship between oceanographic conditions and the advance and retreat of the ice sheet.

The most conspicuous sediment drifts are developed in the western part of Cooperation Sea between Wilkins and Wild Canyons and are referred to as the Wilkins and Wild Drifts (Figs. 4, 7). Kuvaas and Leitchenkov (1992) recognized two major seismic unconformities (P1 and P2). Additional data and reinterpretation have allowed the mapping of a third surface younger than P1 and P2 and a better understanding of the likely age and paleoceanographic significance of the surfaces (Fig. 8). Surface P1 within these sediments marks the transition from a lower homogenous part of the section with mostly irregular reflectors to an upper heterogenous one in which a variety of well-stratified seismic facies are present. New more distal data suggests that P1 may be as old as Cretaceous. Surface P2 marks a change to submarine canyons and related channel and levee deposits and chaotic seismic facies. This transition appears to reflect a dramatic change in the continental margin depositional environment that resulted from the onset of continental glaciation in the Eocene or the arrival of grounded ice sheets at the shelf edge in the early Oligocene, as indicated by ODP Sites 739 and 742 (Barron et al., 1991). This sedimentation change produced thick, prograding foresets above the P2 unconformity beneath the Prydz Bay outer shelf (Kuvaas and Leitchenkov, 1992).

Surface P3, above P2, represents the base of deposits containing abundant, well-stratified sediment drift facies, including sediment waves. Such features imply that strong, presumably westerly flowing, bottom currents played a significant role in drift formation. The changes at this level could have been related to initiation of the Antarctic Circumpolar Current after the opening of Drake Passage around the Oligocene/Miocene boundary or may relate to the a major ice expansion during the Oligocene or Miocene.

A major change in Prydz Bay shelf progradation took place in the late Miocene to middle Pliocene when a fast-flowing ice stream developed and excavated a channel across the shelf on the western side of Prydz Bay, where a surface can be mapped from the shelf to the continental rise (Surface PP15, Fig. 9; Surface A of Mizukoshi et al., 1988). Basal debris carried to the shelf edge deposited in a trough mouth fan on the upper slope (Fig. 10; Boulton, 1990; Larter and Cunningham, 1993). This change may reflect the earliest growth of thick ice on the Antarctic coast deflecting the Lambert Glacier when it advanced (O'Brien and Harris, 1996). This trough mouth fan must contain a reasonably complete record of glacial history because it received siliciclastic sediment when the shelf eroded during major ice advances and hemipelagic material during interglacials and smaller glaciations. Preliminary optical stimulate luminsecence (OSL) dating of sediments from the surface of the fan and ¹⁴C Atomic Mass Spectrometer (AMS) dating of last glacial maximum grounding zone deposits on the shelf (Domack et al., 1998) suggest that the Lambert Glacier last grounded at the shelf edge at 80-120 ka, indicating that not every glacial episode produces a major expansion of the East Antarctic Ice Sheet. This raises questions as to which glacial episodes produced a major advance and what conditions were necessary to produce a major advance.

The Antarctic continental shelf displays many glacially excavated valleys that reach depths of several hundred to more than 2000 m. Some of these valleys have acted as sediment traps in areas of high biological productivity and have accumulated Holocene sedimentary sections with resolution approaching that of ice cores. These sedimentary sections typically consist of biosiliceous oozes with a minor terrigenous component. These oozes record changes in phytoplankton that reflect sea-surface conditions such as temperature and sea-ice cover (Domack and McClennen, 1996). The first of these sections to be cored by ODP in the Palmer Deep off the Antarctic Peninsula provide a high-latitude record comparable to other important ODP Holocene cores such as the Santa Barbara Basin (Kennett, Baldauf, et al., 1994).

The Iceberg Alley shelf valley is a U-shaped glacial valley crossing the Mac Robertson Shelf at 63°E offshore from Mawson Station (Fig. 11). It is as deep as 500 m, and part of the valley on the outer shelf is floored by about 50 m of unconsolidated sediments (Fig. 12). Gravity cores from this area recovered siliceous mud and ooze, some of which show decadal-scale fluctuations in diatom floras (Taylor, 1999).

1.Date the earliest evidence of glacial activity in Prydz Bay and obtain evidence of the Paleogene environment of Antarctica.
2.Link events in the East Antarctic Ice Sheet with changes in the Southern Ocean by drilling Oligocene and younger sediments beneath the continental rise that are distal counterparts of sediments beneath the Prydz Bay continental shelf and slope.
3.Acquire a record of late Miocene and younger ice advances to the shelf edge and interglacial deposits from the Antarctic continental slope by penetrating sequences in the trough mouth fan built by advances of the Lambert Glacier-Amery Ice Shelf.

Site PBS-2A
The Mesozoic and Paleogene sediments beneath outer Prydz Bay form a series of seaward dipping sequences (Figs. 6, 14). Cooper et al. (1991a) recognized sequence PS.2A as Cenozoic glacial sediments and the underlying Sequence PS.2B as preglacial, mostly nonmarine Mesozoic sediment. Site 742 reached middle Eocene-lower Oligocene glacial sediments in Sequence PS.2A without reaching the base of the sequence or nonglacial facies (Hambrey et al., 1991). Hambrey et al. (1991) suggest that the base of the glacial interval was close because they interpreted preglacial alluvial sediment mixed into the lowermost unit in the hole by subglacial deformation.

Proposed Site PBS-2A was chosen to recover core from the Cenozoic sediments below the horizon reached in Site 742 into the top of Sequence PS.2B, the uppermost Mesozoic sediments identified at Site 741. This site should provide an age for the arrival of glaciers in Prydz Bay, a record of changes in depositional environments with the onset of glaciation, and an indication of changes in biota. Site PBS-2A is the primary site because of its thin Quaternary diamict section and a slightly thicker Paleogene section than at Site 742 and should be a more complete record. Site PBS-2A is expected to encounter a thin Quaternary section of diamict and mud overlying an interval of upper Eocene-lower Oligocene stratified diamictite with sandstone and mudstone interbeds similar to sediments in Site 742 below 173 mbsf. Below the interval equivalent to the lower part of Site 742, the lithologies are unknown, but the presence of reworked dinoflagelates and pebbles of ferruginous marine marl, both of Eocene age, at ODP Sites 739 and 742 (Jenkins and Alibert, 1991; Truswell, 1991) suggests a section containing shallow marine sediments. This site should reach Cretaceous nonmarine sediments.

Site PBD-12B
Drilling beneath the Antarctic Peninsula continental rise during Leg 178 showed that the drifts are likely to provide fine-grained equivalents to continental slope and rise sediments. They should also have microfossils for age estimates and interpretation of paleoceanography. Site PBD-12B was selected to acquire a reasonably complete section of the drift record that includes Oligocene and younger sediments. The site is located on the western flank of the Wild Drift (Fig. 14) where Surface P3, which is thought to represent the arrival of grounded ice at the shelf edge during the late Oligocene to early Miocene?, can be reached at about 1000 mbsf. It will also intersect Surface PP.15 that marks the major late Miocene?-late Pliocene? change in glaciation on the shelf and the base of the Prydz Channel Fan. The sediments expected at Site PBD-12B are fine grained hemipelagic clays and distal turbidites with a higher biogenic component in intervals deposited in interglacial periods compared to glacial intervals. Ice-rafted detritus should also be present.

Site PBF-6A
The slope site is aimed at the clinoforms of the Prydz Channel Trough Mouth Fan (Fig. 14). Construction of the fan started in the late Miocene to middle Pliocene when the Lambert Glacier formed a fast-flowing ice stream on the western side of Prydz Bay. The fan grew most during episodes when the Lambert Glacier grounded at the shelf edge, delivering basal debris to the fan apex. This material was then redistributed by sediment gravity flows and meltwater plumes. Between such ice advances, the fan surface has received hemipelagic sediment. Thus, the alternation of facies recovered from the fan should reflect the number of times the East Antarctic Ice sheet has expanded to the shelf edge since late Miocene time. The age of inception of the trough mouth fan will also indicate the time of a major change in glaciation style, probably related to a major increase in the importance of coastal ice masses caused by cooling.

Gravity cores from the fan surface indicate that the section should consist of mud, turbidites, and some debris flows deposited during glacial advances separated by finer, more biogenic intervals. Microfossils present in gravity cores are diatoms and planktonic foraminifers. The optimum position for drilling is in the mid fan, where mapped sequences are all present but not excessively thick. Proposed Site PBF-6A is the primary site in this area.

Contingency Drilling
The development of climatic models and the prediction of future short-term climate changes requires detailed records of past climates to determine what processes operated in the oceans and atmosphere and to document the natural variability of global climate for the Holocene. Ice cores have been the only source of such detailed information. Recent ODP drilling in Saanich Inlet, the Santa Barbara Basin, Cariaco Basin, and Palmer Deep have yielded sedimentary sections with annual resolution comparable to ice cores. Other sites around Antarctica have the potential to provide similar sections. Having more than one sedimentary section from Antarctica would provide the opportunity to study decadal and interannual variability of such climatic features as the Circumpolar Wave and El Niño-Southern Oscillation. Deep valleys on the Mac Robertson Shelf west of Prydz Bay (Fig. 11) contain thick Holocene ooze deposits that probably have such resolution (Fig. 12). Therefore, if time permits, we will try to recover a high-resolution Holocene environmental record by coring biogenic deposits on the outer Mac Robertson Shelf (proposed Site PBS-3A).

The Holocene sequence in Iceberg Alley north of Mawson Station (Site PBS-3A) consists of a flat lying fill within a U-shaped valley cut in older sediments and metamorphic basement (Harris and O'Brien, 1996). Holocene sediments have been imaged by 3.5-kHz echo sounder and intermediate resolution seismic and sampled by gravity coring (Fig. 12). The gravity cores recovered laminate biosiliceous ooze showing laminations, some of which represent monospecific algal or resting spore concentrations. Taylor (1999) interpreted down-core changes in diatom floras as reflecting decadal-scale changes in productivity and water column characteristics during the Holocene. Seismic data indicate that the ooze is about 50 m thick along the valley axis so that cores extending through the full thickness of the deposit should have close to annual resolution. Site PBS-3A is the primary contingency site, but there are a number of locations along the valley axis that contain similar sediments (Fig. 12).

Average conditions in Antarctic waters can be predicted with reasonable confidence; however, interannual variability can be high and the situation at a specific location can vary dramatically. Therefore, we have several layers of contingencies. The primary drilling strategy consists of three sites (Table 1; Fig. 14) with alternates fairly close by that will allow drilling in case of small scale ice problems and drilling difficulties (Fig. 15). We propose an additional strategy to meet the objectives in a less than ideal way in case very heavy ice conditions are encountered on the Prydz Bay shelf. Proposed Site PBD-15A was selected to drill to a depth at which Eocene sediments are thought to occur. A second site was selected on the Mac Robertson Shelf (proposed Site PBS-5A) at which middle Eocene fossils were recovered by gravity coring. If the primary objectives are achieved, time is still available, and ice conditions permit, the Holocene sequence in Iceberg Alley will be cored.

The Prydz Bay shelf site (proposed Site PBS-2A) will be cored by rotary core barrel (RCB) from the outset because poor results were achieved during Leg 119 using the advanced hydraulic piston corer (APC) on the shelf. For the slope and rise sites (Sites PBF-6A and PBD-12B), coring will be with APC to refusal then extended core barrel (XCB) coring to refusal. A new hole will be drilled for RCB coring to total depth. If time permits, we will attempt to triple APC the Mac Robertson Shelf site (Site PBS-3A).

The logs will provide continuous in situ records of the physical and chemical properties of the sediment, which can be interpreted in terms of sediment lithology. This information can be used to complement core data, fill gaps in core recovery, and enable core data to be located at its correct depth position. The continuous nature of the log data makes it ideal for studies of cyclicity (where every cycle counts). The GHMT is likely to provide a magnetic polarity stratigraphy at the drift site, and possibly also at the fan site (depending mostly on the sediment grain size). The FMS resistivity images can be used to identify diamictites, fine-scale bedding, and fabric, including orientation. Synthetic seismograms (and WST check shots, if taken) can be used to correlate hole depths with travel times on the seismic section.

All sampling to be conducted during Leg 188 must be approved by the sampling allocation committee (SAC), consisting of the co-chiefs, staff scientist, and curatorial representative. Sampling plans are subject to modification depending upon the actual material recovered and collaborations that may evolve between scientists during the leg.

Figure 2. A. Overview map of the proposed primary Leg 188 drill sites in respect to port of origin (Freemantle) and final port (Hobart). B. Map of the East Antarctic coastline between 50°E and 90°E, showing the location of Prydz Bay, the Mac Robertson Shelf, Mawson Station, Leg 119 drill sites (squares), and proposed priority one (red circles [web]/black circles [print]) and contingency (white circles [web]/gray circles [print]) drill sites for Leg 188.

Figure 3. Map of Antarctic ice sheets showing drainage divides and flow lines. Prydz Bay is the downstream end of the Lambert Glacier-Amery Ice Shelf drainage basin, which originates entirely in the East Antarctic Ice Sheet. The convergent flow lines feeding the Amery Ice Shelf mean that it responds more sensitively to changes in the interior than other parts of the east Antarctic coast.

Figure 4. Location of Prydz Channel Trough Mouth fan and Wilkins and Wild Drifts. Arrows indicate flow lines of Lambert Glacier during major ice advances.

Figure 5. Model of sediment drift formation along the Antarctic continental margin (Rebesco et al., 1997). During glacial maxima, till transported to the shelf edge slumps, forming sediment gravity flows. Turbidity currents thus formed move down the slope to the rise, where suspended fine sediments are entrained by west-flowing bottom currents and deposited in the drifts west of the submarine canyons.

Figure 6. Interpretation of seismic line through Leg 119 drill sites in Prydz Bay (Cooper et al., 1991a). Shaded area is the part of seismic Sequence PS.2A not sampled by Site 742. Sequence PS.2B comprises Cretaceous nonmarine sediments and Site 742, which bottomed in Eocene glacial sediment. Thus, the lower part of Sequence PS.2A will be drilled to date the oldest glacial sediments in Prydz Bay and to sample any preglacial Cenozoic deposits.

Figure 7. Map showing bathymetry of the Wild Drift, seismic lines, and proposed drill sites.

Figure 8. Seismic section across Wilkins Drift. Seismic horizons:
P3 ­ Onset of current influenced drift deposition (Oligocene?)
P2 ­ Onset of Antarctic glaciation? (Eocene?)
P1 ­ Cretaceous?

Figure 9. Seismic section (north-south) through the Prydz Channel trough mouth fan showing Surface PP.15, which marks the start of trough mouth fan sedimentation and the first cutting of the Prydz Channel.

Figure 10. Model of trough mouth fan sedimentation. A. When the ice stream extends to the continental shelf edge, debris in basal ice and the mobile debris layer at the glacier sole mostly bypass the shelf and are delivered to the shelf edge, where they are redistributed by debris flows and turbidity currents. Fine sediment is entrained in buoyant meltwater plumes and settles on the fan surface. B. During interglacials, the ice has retreated inshore from the shelf edge. Biogenic sedimentation, ice rafting, and minor reworking by slope processes predominate. Ice keel ploughing at the shelf edge results in some remobilization of glacial sediment.

Figure 11. Bathymetric map showing the location of Iceberg Alley, proposed ODP sites, seismic lines, and gravity cores.

Figure 12. A. Seismic line collected with a generator-injector (GI) gun source (Line 186/1901) along the axis of Iceberg Alley. Siliceous mud and ooze appears as a faint horizontally layered unit overlying dipping Paleogene sediments. Proposed ODP sites are indicated. B. A 3.5-kHz echo sounder line collected along the axis of Iceberg Alley. The sediments show horizontal layering in sileceous mud and diatom ooze (SMO) deposits. Proposed ODP sites and existing gravity cores indicated.

Figure 13. Generalized section across Prydz Bay illustrating the Leg 188 drilling strategy. The strategy consists of (1) one hole (Site PBS-2A) drilling the lower part of the Paleogene section (Sequence PS.2A); (2) one hole (Site PBF-6A) drilling the Prydz Channel trough mouth fan to date the development of cross-shelf channels and trough mouth fans and determine the number of times the Lambert Glacier reached the shelf edge from the late Miocene? to the present; and (3) one hole (Site PBD-12B) to investigate glacial-interglacial variations in continental rise sedimentation from the Oligocene to Pleistocene.

Figure 14. Location of primary drill sites on the Prydz Bay shelf, slope, and rise.

Figure 15. Location of alternate sites on the Prydz Bay shelf, slope, and rise.
Table 1. Drill sites

	Shelf (Paleocene section)	Rise (Oligocene Pleistocene)	Slope (late Miocene and younger)	Mac Robertson Shelf (Holocene section)
Primary sites	PBS-2A	PBD-12B	PBF-6A
Alternate sites	PBS-1A	PBD-13A	PBF-5A	PBS-3A
	PBS-6A		PBF-4B	PBS-4A
	PBS-7A		PBF-7A
	PBD-15A
	PBS-5A

blank
Figure 1. Figure 2. Figure 3.
Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Table 2A. Site Time Estimate Table Primary Sites Table 2B. Site Time Estimate Table Alternate Sites Seismic PBD-12B line SAE 33006

Priority: 1
Position: 64°22´46.5"S, 067°13´7.5"E
Water Depth: 3525 m
Sediment Thickness: >2 km
Target Drilling Depth: ~1020 mbsf
Approved Maximum Penetration: 1140 mbsf
Seismic Coverage: SAE 33006 SP 855 (Moved from intersection with SAE 33007 to avoid closure formed by drift topography)

Objectives: To obtain a cored section to the base of the sediment drift on the continental rise to date the major change in sedimentation that led to drift formation (Oligocene?) and to compare the history of sedimentation on the shelf and slope with oceanic sedimentation on the rise.

Drilling Program: APC Hole A to refusal (~200 mbsf), continue with XCB to refusal (~570 mbsf) then RCB Hole B to ~1020 mbsf.

Logging Program: Quad combo (BHC, HLDT, DITE, and sonic) and GHMT

Nature of Rock Anticipated: Mud, ooze, fine sand, and ice-rafted pebbles

PBD-12B Line SAE 33007 Site: PBF-6A

Priority: 1
Position: 66°24.036´S, 072°17.064´E
Water Depth: 1695 m
Sediment Thickness: >2 km
Target Drilling Depth: ~620 mbsf
Approved Maximum Penetration: 620 mbsf
Seismic Coverage: AGSO 149/0901, SP 3957; AGSO 186/2300 SP 545

Objective: Document the number of major advances of the East Antarctic Ice Sheet to the shelf edge since late Miocene to middle Pliocene time by coring a succession of sediments comprised of siliciclastic intervals deposited by output from the Lambert Glacier when it was grounded at or near the shelf edge. The siliciclastic intervals are separated by ooze and hemipelagic mud deposited when the ice was further inshore.

Drilling Program: APC Hole A to refusal (~150 mbsf), continue with XCB to refusal (~350 mbsf) then RCB Hole B to ~620 mbsf.

Logging Program: Quad Combo (BHC, HLDT, DITE, and sonic) and GHMT; LWD-light

Nature of Rock Anticipated: Mud, ooze, diamict, and sand interbeds
PBF-6A Line AGSO 49/0901 PBS-2A Line BMR 33-57 P2
Site: PBS-2A

Priority: 1
Position: 67°41.45´S, 072°13.08´E
Water Depth: 697 m
Sediment Thickness: 1700 m
Target Drilling Depth: ~600 mbsf
Approved Maximum Penetration: 698 mbsf
Seismic Coverage: BMR 33-57P2 SP 493, AGSO 186/1200 SP 3038

Objective: Sample the oldest glacial and youngest preglacial Cenozoic sediments in Prydz Bay.

Drilling Program: RCB Hole A to ~600 mbsf. Hole B will be drilled to ~100 mbsf using the logging-while-drilling-light (LWD-L) tool, which contains resistivity and natural gamma.

Logging Program: Hole A will use the triple combo, FMS-sonic, and GHMT tools; LWD-light in Hole B.

Nature of Rock Anticipated: Diamict, diatom ooze, sand, and mud. Possible sandstone and mudstone in preglacial section.
PBS-2A Line AGSO 186/1200 PBD-13A Line RAE 40006

Priority: 2 (alternative to PBD-12B)
Position: 63°59.807´S, 070°56.519´E
Water Depth: 3450 m
Sediment Thickness: >2 km
Target Drilling Depth: ~1020 mbsf
Approved Maximum Penetration: 1150 mbsf
Seismic Coverage: SAE 33007 SP 429, RAE 40006 SP 117.

Objectives: To obtain a cored section to the base of the sediment drift on the continental rise to date the major change in sedimentation that led to drift formation (Oligocene?) and to compare the history of sedimentation on the shelf and slope with oceanic sedimentation on the rise.

Drilling Program: Same as for PBD-12B.

Logging Program: Same as for PBD-12B.

Nature of Rock Anticipated: Mud, ooze, fine sand, and ice rafted pebbles

See Figure 8 for cross line
PBD-15A Line RAE 40001 Site: PBD-15A

Priority: 2 (alternate to PBS-2A should Prydz Bay be inaccessible)
Position: 63°00´S, 067°38´E
Water Depth: 4125 m
Sediment Thickness: ~4000 m
Target Drilling Depth: ~850 mbsf
Approved Maximum Penetration: 850 mbsf
Seismic Coverage: RAE 40001 SP 100, RAE 40006 SP 117

Objective: Alternate to PBS-2A should Prydz Bay be inaccessible. Seismic surfaces thought to mark the onset of Cenozoic glaciation can be drilled in the relatively thin distal drift section at this location.

Drilling Program: Same as for PBD-12B

Logging Program: Triple Combo, FMS-sonic, GHMT

Nature of Rock Anticipated: Mud, silt, biogenic ooze, and rare sand
PBF-4B Line JNOC TH84/9-1-SMG Site: PBF-4B

Priority: 2 (alternate to PBF-6A)
Position: 66°30.5652´S, 072°24.0954´E
Water Depth: 1305 m
Sediment Thickness: ~4000 m
Target Drilling Depth: ~699 mbsf
Approved Maximum Penetration: 699 mbsf
Seismic Coverage: JNOC 84/9-1-SMG SP 10700, AGSO 149/0901 (site moved from intersection by PPSP to avoid potential hydrocarbon trap)

Objectives: Same as for PBF-6A.

Drilling Program: Same as for PBF-6A

Logging Program: Same as for PBF-6A

Nature of Rock Anticipated: Mud, ooze, diamict, and sand interbeds

See seismic line for PDF-6A PBF-4B Line AGSO 149/0901 Site: PBF-5A

Priority: 2 (alternate to PBF-6A)
Position: 66°19.003´S, 072°16.618´E
Water Depth: 1920 m
Sediment Thickness: ~4000 m
Target Drilling Depth: ~578 mbsf
Approved Maximum Penetration: 578 mbsf
Seismic Coverage: AGSO 149/0901 SP 4463, AGSO 186/2400 SP 976

Objective: Same as for PBF-6A.

Drilling Program: Same as for PBF-6A

Logging Program: Same as for PBF-6A

Nature of Rock Anticipated: Mud, ooze, diamict, and sand interbeds

See seismic line for PDF-6A
PBF-7B Line BMR 33-32P1 Site: PBF-7B

Priority: 2 (alternate to PBF-6A, chosen to be further away from PBF-6A than other alternates as suggested by ODP)
Position: 66°05.267´S, 072°07.297´E
Water Depth: 3775 m
Sediment Thickness: ~4000 m
Target Drilling Depth: ~417 mbsf
Approved Maximum Penetration: 417 mbsf
Seismic Coverage: RAE 40005A SP 2872, BMR 33-32P1 SP 304

Objective: Same as for PBF-6A. Thinner section would make for a less complete record and structural position might make the section sandier.

Drilling Program: Same as for PBF-6A

Logging Program: Same as for PBF-6A

Nature of Rock Anticipated: Mud, ooze, diamict, and sand interbeds
PBF-7B Line RAE 40005A PBS-1A Line AGSO 186-0900 Site: PBS-1A

Priority: 2 (alternate to PBS-2A if PBS-2A site is inaccessible)
Position: 67°36.95´S, 073°18.34´E
Water Depth: 600 m
Sediment Thickness: 2000 m
Target Drilling Depth: ~648 mbsf
Approved Maximum Penetration: 648 mbsf
Seismic Coverage: BMR 33-27P2 SP3850, AGSO 186/0900 SP 6013

Objectives: Same as for PBS-2A

Drilling Program: Same as for PBS-2A

Logging Program: Same as for PBS-2A

Nature of Rock Anticipated: Same as for PBS-2A
PBS-1A Line BMR 33-27-P2 Site: PBS-3A

Priority: 2
Position: 66°56.55´S, 063°6.93´E
Water Depth: 470 m
Sediment Thickness: >1 km (ooze section = 50 m)
Target Drilling Depth: ~50 mbsf
Approved Maximum Penetration: 50 mbsf
Seismic Coverage: AGSO 186/1901 SP 4450

Objective: To obtain a continuous cored section to the base of the thick Holocene biosiliceous ooze section to provide a marine sedimentary record of environmental change with similar resolution to that of ice cores.

Drilling Program: Three APC holes to TD to provide a complete succession.

Logging Program: None

Nature of Rock Anticipated: Biosiliceous ooze, silt, clay, and ice-rafted pebbles.
PBS-3A Line #-needed blank Site: PBS-4A

Priority: 2 (alternate to PBS-3A).
Position: 67°07.92´S, 062°59.57´E
Water Depth: 555 m
Sediment Thickness: >1 km (ooze section 50 m)
Target Drilling Depth: ~50 mbsf
Approved Maximum Penetration: 50 mbsf
Seismic Coverage: AGSO 186/1901 SP 2901

Objectives: Same as PBS-3A

Drilling Program: Three APC holes to TD to provide a complete section

Logging Program: None

Nature of Rock Anticipated: Biosiliceous ooze, silt, clay, and ice-rafted pebbles

See Figure 12 for seismic cross section PBS-5A Line AGSO 186-1800 NS Site: PBS-5A

Priority: 2 (alternate to PBS-2A should Prydz Bay be inaccessible)
Position: 66°47.808´S, 063°15.597´E
Water Depth: 315 m
Sediment Thickness: ~1 km
Target Drilling Depth: ~50 mbsf
Approved Maximum Penetration: 50 mbsf
Seismic Coverage: AGSO 186/1800 SP 883, BMR 33-5P2 SP 11760

Objectives: Alternate to PBS-2A if Prydz Bay is inaccessible. Gravity cores containing Paleogene marine fossils indicate that a shallow hole at PBS-5A may recover mid-Eocene sediments.

Drilling Program: RCB to TD

Logging Program: None

Nature of Rock Anticipated: Diamict at surface, then siltstone, sandstone, and mudstone

PBS-5A Line BMR 33-5P2 Site: PBS-6A

Priority: 2 (alternate to PBS-2A should that hole be unable to reach total depth TD)
Position: 67°46.638´S, 072°11.529´E
Water Depth: 697 m
Sediment Thickness: 1400 m
Target Drilling Depth: ~294 mbsf
Approved Maximum Penetration: 294 mbsf
Seismic Coverage: AGSO 186/0900 SP 2939, AGSO 186/1300 SP 678

Objectives: Alternate to PBS-2A should that hole be unable to reach TD. PBS-6A is updip from PBS-2A and intersects the lower part of the Cenozoic section to be drilled at PBS-2A.

Drilling Program: Same as for primary site

Logging Program: Same as for primary site

Nature of Rock Anticipated: Diamict, mud, mudstone, and sandstone
PBS-6A Line AGSO 186/0900 PBS-6A Line AGSO 186/1300 PBS-7A Line BMR 33-27-P2 Site: PBS-7A

Priority: 2 (alternate to PBS-1A or PBS-2A should that hole be unable to reach TD)
Position: 67°42.91´S, 073°26.112´E
Water Depth: 592 m
Sediment Thickness: 1460 m
Target Drilling Depth: ~276 mbsf
Approved Maximum Penetration: 276 mbsf
Seismic Coverage: BMR 33-27P2 SP 3393, SAE 3308 SP 403.23

Objectives: Alternate to PBS-2A or PBS-1A should we be unable to reach TD at those sites. PBS 7A is updip from PBS-1A and intersects the lower part of the Cenozoic section to be drilled in PBS-1A.

Drilling Program: Same as for PBS-2A or PBS-1A

Logging Program: Same as for PBS-2A or PBS-1A

Nature of Rock Anticipated: Clay, silt, biosiliceous ooze, sand, and diamict. Possible sandstone and mudstone in preglacial section PBS-7A Line SAE 33008

Co-Chief
Alan K. Cooper
Office of Marine Geology
United States Geological Survey
345 Middlefield Road, MS 999
Menlo Park, CA 94025
U.S.A.
Internet: alan@octopus.wr.usgs.gov
Work: (650) 329-5157
Fax: (650) 329-5190

Co-Chief
Philip E. O'Brien
Petroleum and Marine Division
Australian Geological Survey Organisation
GPO Box 378
Canberra, ACT 2601
Australia
Internet: pobrien@agso.gov.au
Work: (61) 2-6249-9409
Fax: (61) 2-6249-9920

Staff Scientist
Carl Richter
Ocean Drilling Program
Texas A&M University
1000 Discovery Drive
College Station , TX 77845-9547
U.S.A.
Internet: carl_richter@odp.tamu.edu
Work: (409) 845-2522
Fax: (409) 845-0876

Paleontologist (Diatom)
Steven M. Bohaty
Department of Geosciences
University of Nebraska, Lincoln
214 Bessey Hall
Lincoln, NE 68588-0340
U.S.A.
Internet: sbohaty@unlgrad1.unl.edu
Work: (402) 472-2648
Fax: (402) 472-4917

Paleontologist (Diatom)
Jason M. Whitehead
Department of Geology
Hamilton College
198 College Hill Road
Clinton, NY 13323
U.S.A.
Internet: jwhitehe@hamilton.edu
Work: (315) 859-4699
Fax: (315) 859-4807

Paleontologist (Foraminifer)
Patrick G. Quilty
School of Earth Sciences
University of Tasmania
GPO Box 252-79
Hobart, Tasmania 7001
Australia
Internet: p.quilty@utas.edu.au
Work: (61) 3-6226-2814
Fax: (61) 3-6223-2547

Sedimentologist
Michele A. Rebesco
Geofisica Della Litosfera
Osservatorio Geofisico Sperimentale
PO Box 2011
Trieste 34016
Italy
Internet: mrebesco@ogs.trieste.it
Work: (39) 40-2140252
Fax: (39) 40-327307

Sedimentologist
Kari O. Strand
Department of Geology
Oulun Yliopisto
Linnanmaa
Oulu 90570
Finland
Internet: strand@babel.oulu.fi
Work: (358) 8-553-1451
Fax: (358) 8-553-1484

LDEO Logging Scientist
Trevor Williams
Lamont-Doherty Earth Observatory
Columbia University
Borehole Research Group
Palisades, NY 10964
U.S.A.
Internet: trevor@ldeo.columbia.edu
Work: (914) 365-8626
Fax: (914) 365-3182

Schlumberger Engineer
Steve Kittredge
Schlumberger Offshore Services
369 Tristar Drive
Webster, TX 77598
U.S.A.
Internet: kittredge@webster.wireline.slb.com
Work: (281) 480-2000
Fax: (281) 480-9550

Operations Manager
Michael A. Storms
Ocean Drilling Program
Texas A&M University
1000 Discovery Drive
College Station, TX 77845-9547
U.S.A.
Internet: michael_storms@odp.tamu.edu
Work: (409) 845-2101
Fax: (409) 845-2308

Laboratory Officer
Bill Mills
Ocean Drilling Program
Texas A&M University
1000 Discovery Drive
College Station, TX 77845-9547
U.S.A.
Internet: bill_mills@odp.tamu.edu
Work: (409) 845-2478
Fax: (409) 845-0876

Marine Lab Specialist: Yeoperson
Jo Ribbens
Ocean Drilling Program
Texas A&M University
1000 Discovery Drive
College Station, TX 77845-9547
U.S.A.
Internet: jo_ribbens@odp.tamu.edu
Work: (409) 845-8482
Fax: (409) 845-0876

Marine Lab Specialist: Chemistry
Erik Moortgat
Ocean Drilling Program
Texas A&M University
1000 Discovery Drive
College Station, TX 77845-9547
U.S.A.
Internet: erik_moortgat@odp.tamu.edu
Work: (409) 845-7716
Fax: (409) 845-0876

Marine Lab Specialist: Chemistry
Anne Pimmel
Ocean Drilling Program
Texas A&M University
1000 Discovery Drive
College Station, TX 77845-9547
U.S.A.
Internet: anne_pimmel@odp.tamu.edu
Work: (409) 845-8482
Fax: (409) 845-0876

Marine Lab Specialist: Core
Johanna M. Suhonen
Ocean Drilling Program
Texas A&M University
1000 Discovery Drive
College Station, TX 77845-9547
U.S.A.
Internet: johanna_suhonen@odp.tamu.edu
Work: (409) 845-9186
Fax: (409) 845-0876

Marine Lab Specialist: Curator
Erinn McCarty
Ocean Drilling Program
Texas A&M University
1000 Discovery Drive
College Station, TX 77845-9547
U.S.A.
Internet: erinn_mccarty@odp.tamu.edu
Work: (409) 845-8482
Fax: (409) 845-0876

Marine Lab Specialist: Downhole Tools, Thin Sections
Sandy Dillard
Ocean Drilling Program
Texas A&M University
1000 Discovery Drive
College Station, TX 77845-9547
U.S.A.
Internet: edgar_dillard@odp.tamu.edu
Work: (409) 845-2481
Fax: (409) 845-0876

Marine Lab Specialist: Paleomagnetics
Matt O'Regan
Ocean Drilling Program
Texas A&M University
1000 Discovery Drive
College Station, TX 77845-9547
U.S.A.
Internet: matthew_o'regan@odp.tamu.edu
Work: (409) 845-2483
Fax: (409) 845-0876

Marine Lab Specialist: Photographer
Roy Davis
Ocean Drilling Program
Texas A&M University
1000 Discovery Drive
College Station, TX 77845-9547
U.S.A.
Internet: roy_davis@odp.tamu.edu
Work: (409) 845-8482
Fax: (409) 845-4857

Marine Lab Specialist: Physical Properties
Patrick Riley
Ocean Drilling Program
Texas A&M University
1000 Discovery Drive
College Station, TX 77845-9547
U.S.A.
Internet: patrick_riley@odp.tamu.edu
Work: (409) 845-2480
Fax: (409) 845-0876

Marine Lab Specialist: Underway Geophysics
Steve Prinz
Scripps Institution of Oceanography
University of California, San Diego
Ocean Drilling Program
West Coast Repository
La Jolla, CA 92093-0231
U.S.A.
Internet: steve_prinz@odp.tamu.edu
Work: (858) 534-1657
Fax: (858) 534-4555

Marine Lab Specialist: X-Ray
Jaquelyn Ledbetter
Ocean Drilling Program
Texas A&M University
1000 Discovery Drive
College Station, TX 77845-9547
U.S.A.
Internet: jaque_ledbetter@odp.tamu.edu
Work: (409) 845-8482
Fax: (409) 845-0876

Marine Electronics Specialist
John Pretorius
Ocean Drilling Program
Texas A&M University
1000 Discovery Drive
College Station, TX 77845-9547
U.S.A.
Internet: john_pretorius@odp.tamu.edu
Work: (409) 845-5135
Fax: (409) 845-0876

Marine Electronics Specialist
Pieter Pretorius
Ocean Drilling Program
Texas A&M University
1000 Discovery drive
College Station, TX 77845-9547
U.S.A.
Internet: pieter_pretorius@odp.tamu.edu
Work: (409) 845-5135
Fax: (409) 845-0876

Marine Logistics Coordinator
John Dyke
Ocean Drilling Program
Texas A&M University
1000 Discovery Drive
College Station, TX 77845-9547
U.S.A.
Internet: john_dyke@odp.tamu.edu
Work: (409) 845-2424
Fax: (409) 845-2380