Site summaries

Site SCS-6A

Priority: Primary (high)
Position: 18°21.117′N, 116°23.45′E
Water depth (m): 3843
Target drilling depth (mbsf): 1930
Approved maximum penetration: Approved to basement + 100 m with full coring. Drilling through the top 900 m without coring is pending EPSP approval. (Estimated total depth = 1930 mbsf)
Survey coverage (track map; seismic profile): Bathymetric sketch and site track map (Figs. AF1, AF2) Deep-penetration seismic reflection:
• Primary line: 08ec1573 (SP400) (Fig. AF3)
• Crossing line: 08ec2678 (SP6149) (Fig. AF4)
Objectives: • Date the oldest oceanic crust near the continent/ocean boundary of the South China Sea
• Measure magnetization, mineralization, and geochemical compositions of basement rocks
• Obtain basement rocks to ascertain the causes of sharp magnetic contrasts between different sub-basins
• Study the paleoceanographic response to the opening of the South China Sea
Drilling program: Hole A (APC/XCB coring will only be completed if full coring is required by EPSP):
• APC to refusal with nonmagnetic core barrels, core orientation (FlexIT tool), and APCT-3
• XCB to refusal
Hole B:
• Jet-in test for reentry system
Hole C:
• Reentry system (20, 16, and 10¾ inch casing to ~900 mbsf)
• RCB with nonmagnetic core barrels to 1930 mbsf (one bit change at ~1830 mbsf)
Downhole logging program: Hole A:
• Triple combo
• FMS-sonic
Hole C:
• Triple combo
• FMS-sonic
• VSI if time and hole conditions allow
• UBI/MMM if time and hole conditions allow
Nature of rock anticipated: (Calcareous) mudstone, siltstone, sandstone, basalt