167 Preliminary Report


The main objectives for drilling Leg 167 were to investigate the evolution of oceanogaphic conditions in the North Pacific Ocean and to document changes in flow of the California Current system and associated changes in coastal upwelling. These data will be used to reconstruct North Pacific climate conditions through the Neogene, concentrating upon the time period since the advent of Northern Hemisphere glaciation, about 2.5 Ma to the present. Four of the drill sites (Sites 1010, 1011, 1014, and 1016) sampled middle to upper Miocene sediments to reconstruct a Neogene history of the California Current. The results of Leg 167 drilling will also be used to better understand the links between climates of the North Pacific Ocean and western North America, particularly in terms of temperature change and changes in precipitation.

The 13 sites are organized into three transects across the California Current (Baja Transect, ~30°N; Conception Transect, ~35°N; and Gorda Transect, ~40°N) and one coastal transect extending from northern Baja California to the California/Oregon border, 30°N to 42°N. Each of the three transects across the California Current compares deep-water sites near the core of the California Current to coastal upwelling sites near shore. The coastal transect examined variations in upwelling and productivity along the California Margin, and also intermediate-water properties in many of the basins of the California Continental Borderland.

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