DRILLING STRATEGY
The drill plan includes six primary sites that span water depths from 2100 to 4600 m (Tables 1, 2).
Targets will be drilled from north to south (TSO-2B, SubSAT-1B, TSO-3C, TSO-5C, TSO-6A,
and TSO-7C). Alternate sites were selected for TSO-6A and TSO-7C in the event an iceberg is
sitting atop the primary target. Because of time constrains, three alternate sites (TSO-4B, SubSAT
3B, and SubSAT-4B/C) cannot be included in the proposed one-leg effort of 56 days; however,
these alternate sites will serve as backups to the primary targets. If time is saved as a result of early
departure from port or conservative drilling time estimates, additional time will be used to enhance
the scientific objectives with the following priorities: (1) insure continuous sections at high
resolution triple-cored intervals (i.e., recover a fourth hole if needed to complete a composite
section), (2) maintain the latitudinal transect composed of four high-resolution sites, (3) deepen site
TSO-7C, and (4) deepen other sites to approved target depth or drill alternate sites.
Successful recovery at the primary sites will provide the following:
- Two deep holes (700 m) at Sites TSO-2B and TSO-6A that will complete a Cenozoic
latitudinal transect between 35° and 72°S when combined with ODP Site 704 (Meteor
Rise, as well as other Leg 114 sites), Sites 689 and 690 (Leg 113, Maud Rise), and DSDP
Site 360 (South African Continental Rise, Leg 40).
- A depth transect on the Agulhas Ridge around 43°S that includes Sites TSO-2B (2104
m), TSO 3C (3718 m), SubSAT-1B (4620 m) and one site on the Meteor Rise around
47°S when Site TSO-5C (4418 m) is combined with Site 704 (2532 m).
- Complete composite sections of the late Neogene with moderate sedimentation rates by
triple APC/XCB penetration to 200 m at Sites TSO-3C (3 cm/k.y.) and TSO-5C (8
cm/k.y.).
- One ultra-high-resolution transect between 41° and 53°S (SubSAT-1B, TSO-6A, and
TSO-7C) recovered by triple APC/XCB.
Criteria for discontinuing operation at a particular site will include poor recovery, inability to
construct a composite section at high-resolution sites, massive sediment disturbance (i.e., mass
flows, turbidites, etc.), extremely slow penetration rate, drilling into sediment ages that are beyond
the scope of the scientific objectives, and persistent heavy weather that prevents drilling or leads to
unproductive operations.
To 177 Proposed Primary Sites
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