Priority: 2 (alternate to APRIS-01A)
Position: 64°35.06'S, 69°24.26'W
Water Depth: 2850 m
Sediment Thickness: >2000 m
Approved Maximum Penetration: 1320 mbsf
Seismic Coverage: Line IT92-114 SP 2250; Lines intersect at AI97-235A SP 9300 and AI97
236 SP 291
Objectives: The objectives of Site APRIS-05A are to:
1. Obtain a high-resolution history of Antarctic Peninsula glaciation for the last 6-10 m.y.
2. Determine the onset of drift formation by sampling the base of Unit M4.
Drilling Program: Double APC until refusal (about 200 m), continue with XCB until refusal (about 800 m), and then either RCB from 750 m to base of target section at the same site or single APC and XCB to base of target section at Site APRIS-06A. Site APRIS-06A is offset about 90 km from APRIS-05A and is located where the upper part of the section is thinner and the base of the target section is at only about 800 mbsf. Offset of the site is required if the stratigraphic control seriously degrades below the silica diagenetic BSR at about 590 mbsf at Site APRIS-05A.
Logging and Downhole Operations: Standard suites IPLT-DLT and FMS-sonic, plus GHMT.
Nature of Rock Anticipated: Alternating (interglacial) biosiliceous clay and (glacial) laminated
barren gray clay, becoming claystone downhole.
