Priority: 2 (alternate to APRIS-02A)
Position: 65°55.04'S, 77°13.55'W
Water Depth: 3900 m
Sediment Thickness: >2000 m
Approved Maximum Penetration: 700 mbsf
Seismic Coverage: Line AI95-136A SP 5550
Objectives: The objectives of Site APRIS-04A are to:
1. Sample the deeper part of the stratigraphic section not drilled at Site APRIS-03A.
2. Obtain a high-resolution history of Antarctic Peninsula glaciation for the last 6-10 m.y.
3. Determine the onset of drift formation by sampling the base of Unit M4.
Drilling Program: Double APC until refusal (about 200 m) then XCB. The site is offset by ~110 km from main Site APRIS-03A. Offset required if stratigraphic control seriously degraded below silica diagenetic BSR at ~670 m at main site.
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.
To 178 Site APRIS-05
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