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SITE SUMMARIES (continued)

Site NNB-04A

Priority: 2
Position: 45°11.8'N; 44°22.6'W
Water Depth: 4624 m
Sediment Thickness: 135 m, from stacking and wide-angle velocity models
Target Drilling Depth: 235 mbsf
Approved Maximum Penetration: 500 mbsf

Seismic Coverage: Ewing 00-07 line 2 MCS; SP 29227 (CMP 234827) (see Figs. F3, F5, F8)


  1. Primary objective: Composition and igneous/tectonic history of basement. If Site NNB-01 samples continental basement, then Sites NNB-03A to NNB-06A will systematically sample basement eastward to define the maximum seaward limit of continental crust, landward limit of ocean crust, and the character of any intervening transition. If this basement high is serpentinite, this hole might be deepened to bit destruction in order to investigate the variation in composition, alteration, and possible melt interaction with depth.

Operational Program: see "Alternate Sites: Proposed Site NNB-04A" 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 and silty clays.

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