Site summaries (continued)

Proposed Site LOUI-2B (Seamount 33.7°S - Suiko equivalent)

Priority: Primary site
Position: 33°41.90′S, 171°26.94′W
Water depth (m): 1259
Target drilling depth (mbsf): ~410 (59 m sediment; ≥350 m basement)
Approved maximum penetration (mbsf): 420 (350 m basement; additional basement penetration must be reviewed by the operator during drilling operations)
Survey coverage: • AMAT02RR (Fig. AF4)
• Line AMAT 32.33-12 (CDP 45442) (Fig. AF5)
• Line AMAT 32.33-13 (CDP 46611) (Fig. AF6)
Objective: (see text for details) 1. Core thin sediment cover and igneous basement until enough igneous units suitable to acquire accurate paleolatitudes and 40Ar/39Ar ages are recovered.
2. Study the geochemical evolution of this guyot.
Drilling, coring, and downhole measurement program: • RCB coring to TD.
• FFF deployment and two bit changes (two reentries).
• Wireline logging (triple combo, FMS-sonic, and magnetometer).
Anticipated lithology (mbsf): • 0–15: pelagic ooze
• 15–59: lithified limestones, volcaniclastics, and minor lava flows(?)
• >59: basalt (~60 m.y. old)
Site characterization: A preliminary 40Ar/39Ar age of 58.5 Ma, based on replicated plagioclase analyses of SO167 sample 154/2, makes this seamount approximately equivalent to the 61 Ma Suiko Seamount in the Emperor Seamount Trail. This relatively small edifice has a smooth pelagic cap between 10 and 15 m thick, based on 3.5 kHz CHIRP data. Also, it is void of any clear posterosional peaks beneath the thin sedimentary sequences. Site LOUI-2B is close to the center of the volcanic structure where a presumed intercalated sequence of volcaniclastic and lava flows is thinnest (~45 m).