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SITE SUMMARIES (continued)

Site NNB-01B

Priority: 2
Position: 45°23.5'N; 44°45.5'W
Water Depth: 4563 m
Sediment Thickness: 2180 m, from stacking and wide-angle velocity models
Target Drilling Depth: 2280 mbsf
Approved Maximum Penetration: 2600 mbsf; drill without coring to 800 mbsf

Seismic Coverage: Ewing 00-07 line 2 MCS; SP 28486 (CMP 228893) (see Figs. F3, F5, F7)


  1. Primary objective: Composition and igneous/tectonic history of basement. The nature of the U reflection and the composition and origin of the high-velocity interval between U and basement. Subsidence history of the stratigraphic sequence immediately above reflector U.
  2. Secondary Objective: Age of a prominent reflection (horizon Au?) which 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: Same as at proposed Site NNB-01A, but with a three-casing string. See "Alternate Sites: Proposed Site NNB-01B" 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 claysontes (equivalent to Hatteras formation); possible limestone beds (?Blake-Bahama formation).

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