Ocean Drilling Program, United States

More than 7 km of long and relatively continuous sediment sequences from 11 sites in the southeast and equatorial Pacific were recovered during Leg 202 for the study of the Earth's climate and biogeochemical systems on scales that range from tectonic (millions of years) to orbital (tens to hundreds of thousands of years) and centennial to millennial (hundreds to thousands of years). These materials will be used to test a broad set of hypotheses on (1) the evolution of the South Pacific Ocean as it responds to and modulates the effects of major tectonic and climatic events, such as the opening of the Drake Passage, uplift of the Andes Mountains, closure of the Isthmus of Panama, and major expansion of polar ice sheets; (2) linkage between climate and biogeochemical changes in the high latitudes and the equatorial Pacific, related to rhythmic changes in Earth's orbit, and the relationship of such changes to well-known glacial events of the Northern Hemisphere; and (3) global and regional changes in climate, biota, and ocean chemistry on timescales of centuries to millennia to millions of years. Three sites (1236, 1237, and 1241) targeted sequences with relatively low sedimentation rates of <30 m/m.y. to obtain long records of climate and oceanographic change representing the Neogene and, in some cases, the late Paleogene that are not subject to severe burial diagenesis. Two sites (1238 and 1239) targeted moderate sedimentation rates of 30-80 m/m.y. to assess orbital-scale climate and biogeochemistry oscillations at a resolution suitable for the tuning of timescales and examination of changing responses to orbital forcing during the late Neogene.