During the past several years, ODP has been drilling in the Atlantic ocean to study past changes in Earth's climate. Leg 177 represents the southernmost anchor of sites needed to complete the Atlantic paleoceanographic transect. The strategy during Leg 177 was to drill a series of sites along a latitudinal transect that encompasses the past dynamic range of the Antarctic sea-ice field and frontal boundary movements within the ACC. Sites were selected along a bathymetric gradient, ranging from 2100 to 4600 m, to study changes in deep-water circulation.

The drilling strategy included seven primary sites to recover expanded late Neogene sections across latitude and depth transects in the Subantarctic and Antarctic regions. We specifically targeted sites with high sedimentation rates on sediment drifts and in the region of the circumantarctic biogenic silica belt (Fig. 9). Four of the sites (Sites 1089, 1091, 1093, and 1094) exhibit average sedimentation rates exceeding 100 m/m.y., offering the opportunity for high-resolution paleoclimatic studies. The two southern sites (1093 and 1094) are the first to recover a complete composite section by triple-APC/XCB coring from the circumantarctic silica belt.

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