PRELIMINARY REPORT OF GEOPHYSICAL AND GEOLOGICAL SURVEYS IN THE AMUNDSEN SEA, WEST ANTARCTICA

• Main Authors: ヤマグチ カズオ, タムラ ヤスオ, ミズコシ イクロウ, ツル テツロウ, Kazuo YAMAGUCHI, Yasuo TAMURA, Ikuro MIZUKOSHI, Tetsuro TSURU
• Format: Report
• Language: English
• Published: Technology Research Center, Japan National Oil Corporation 1988
• Subjects: Antarctic; West Antarctica; Amundsen Sea; Bellingshausen Sea; Pacific; Antarc*; Antarctica
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=2562; http://id.nii.ac.jp/1291/00002562/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=2562&item_no=1&attribute_id=18&file_no=1

Geophysical and geological surveys in the Amundsen Sea, West Antarctica were conducted during the 1986-1987 Antarctic summer season. The study area covers the continental rise and the abyssal plain. The surveys revealed the existence of the sedimentary basin in the Amundsen Sea as the westward extension of the Bellingshausen Sea Basin. The basement of the basin becomes shallow in depth and rough in topography toward the west in a manner of stepwise change along the continental rise and the abyssal plain, which are clearly observed in seismic sections. In the continental rise, the presence of thick sediments which exceeded about 2.0s in two-way time was recognized. Characteristic sedimentary facies patterns in the continental rise such as dunes, channels, buried channels and migrating waves were observed in the upper parts of the sediment columns. In the abyssal plain, the acoustic basement showed remarkably complex relief and distorted reflections were observed in the sediments deposited on structural lows of the basement. The sediments were generally thin, about 0.5s in two-way time. From the viewpoint of depth, location, configuration, reflection pattern of the acoustic basement and thickness of total sediments, the study area can be divided into three parts, i.e., eastern part, central part and western part. The boundaries between them may be assumed to correspond to fracture zones which extend from the Pacific-Antarctic Ridges.