Core Summary

Approximately 4000 m of sediment ranging in age from middle Eocene to Holocene was recovered during Leg 177. To the extent possible, composite records were constructed at each site from cores in multiple holes by aligning features in the signals of core-logging data. Successful recovery was made of the following:

1.A latitudinal transect of Pleistocene sections across the ACC (41°-53°S), including Sites 1089 (41°S), 1091 (47°S), 1093 (50°S), and 1094 (53°S) (Fig. 11). Average sedimentation rates vary between 130 and 250 m/m.y., permitting studies at millennial-scale resolution (Fig. 12). Close to the base of three of these sites (1089, 1091, and 1093) upper Pliocene sequences with sedimentation rates between 30 and 84 m/m.y. were recovered.

2.Several Pliocene-Pleistocene sections with lower sedimentation rates averaging between 7 and 33 m/m.y., including Sites 1088 (41°S), 1090 (43°S), and 1092 (47°S).

3.Two relatively complete upper Miocene sequences at Sites 1088 (41°S) and 1092 (47°S) with sedimentation rates between 7-17 and 30-38 m/m.y. in the late to middle late Miocene and in the early late Miocene, respectively (Fig. 13). In conjunction with Leg 113 Sites 689 and 690, these sites represent an upper Miocene latitudinal transect across the Southern Ocean.

4.A lower Miocene to middle Eocene sequence (~18 to 46 Ma) at Site 1090 (43°S) that has a superb polarity reversal stratigraphy and was recovered in multiple holes to ensure a verifiably complete section.

5.Two depth transects of cores that intersect each of the major deep water masses in the Southern Ocean: (1) the Agulhas Ridge transect that includes Sites 1088 (2083 m), 1090 (3699 m), and 1089 (4624 m); and (2) the Meteor Rise transect that includes Site 1092 (1976 m), Leg 117 Site 704 (2532 m), and Site 1091 (4620 m).

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