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SITE SUMMARIES (continued)

Site NNB-03A

Priority: 2
Position: 45°19.6'N; 44°37.9'W
Water Depth: 4553 m
Sediment Thickness: 1240 m, from stacking and wide-angle velocity models
Target Drilling Depth: 1340 mbsf
Approved Maximum Penetration: 1600 mbsf; drill without coring to 500 mbsf

Seismic Coverage: Ewing 00-07 line 2 MCS; SP 28731 (CMP 230858) (see Figs. F3, F5, F8)


  1. Primary objective: Composition and igneous/tectonic history of basement. Subsidence history of the stratigraphic sequence immediately above basement.
  2. Secondary objective: Age of a prominent reflection (horizon Au?) marks the initiation of abyssal current-controlled deposition in the basin, implications for a northern Atlantic gateway, and sedimentary characteristics of subsequent current-controlled sedimentation. Stratigraphic sequence development compared to development of synchronously deposited, formally defined formations that are widely developed in the western North Atlantic.

Operational Program: The drilling/logging plan consists of a two–casing string strategy with a 103/4-in casing liner as contingency to ensure we can obtain deep sediments and basement. We will drill 20-in casing in to ~80 mbsf and then 16-in casing to ~475 mbsf. RCB coring will extend from 500 mbsf down to, and into, basement. Logging will consist of the two standard logging strings and a checkshot with the WST. After the primary deep objectives have been achieved, if time permits, we will core the upper ~500 m of section in order to obtain a complete sedimentary record at this site. See "Alternate Sites: Proposed Site NNB-03A" section and Table T2.

Logging and Downhole: Three logging runs (1) triple combo tool string, (2) FMS-sonic tool string, and (3) checkshot with WST. Core orientation and temperature tools if alternate plan for shallow coring occurs.

Nature of Rock Anticipated: From top to base: clays, silty clays, and claystones (equivalent to Blake Ridge formation); siliceous and/or cherty claystones (equivalent to Bermuda Rise formation); multicolored claystones (equivalent to Hatteras formation).

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