Site summaries (continued)

Proposed Site LOUI-3B (Seamount 36.9°S - Nintoku equivalent)

Priority: Primary site
Position: 36°54.26′S, 169°47.91′W
Water depth (m): 982
Target drilling depth (mbsf): ~415 (65 m sediment; ≥330 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. AF7)
• Line AMAT 36.9-1 (CDP 19406) (Fig. AF8)
• Line AMAT 36.9-2 (CDP 20564) (Fig. AF9)
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 one bit change (one reentry). Only one bit change is planned at this site because of time constraints.
• Wireline logging (triple combo, FMS-sonic, and magnetometer).
Anticipated lithology (mbsf): • 0–10: pelagic ooze
• 10–65: lithified limestones, volcaniclastics, and minor lava flows(?
• >65: basalt (~54 m.y. old)
Site characterization: Site LOUI-3B is placed toward the center of the 36.9°S guyot and away from a thick seaward-dipping sequence of volcaniclastics. Posterosional volcanism was not identified on this seamount based on bathymetry and seismic data. Seamount 35.8°S (located 1.1° south) has a magnetic anomaly pattern that yields a paleopole of ~49° ± 7°S, indicative of indiscernible hotspot motion since 59 Ma, and may serve as a direct comparison to drilling results at Site LOUI-3B (Fig. F10). Multichannel seismic reflection profiles show a relatively thin pelagic cap at Site LOUI-3B (compared to other places on this guyot platform) that is estimated to be ~10 m thick based on 3.5 kHz CHIRP data.