Drilling Strategy | Table of Contents

CONTINGENCY PROGRAM
(Kuroshio Current)

The Kuroshio Current (Black Current) is the biggest western boundary surface current in the western Pacific. It plays an important role in the meridional transports of heat, mass, momentum, and moisture from the western Pacific warm pool (WPWP) to high latitudes of the north Pacific. Its role in the Pacific is as important as the Gulf Stream in the north Atlantic, yet little is known about its long-term evolution. The lack of knowledge of this important current system has hindered the construction of a complete scenario of climatic evolution for the Pleistocene, if not the entire Cenozoic of the west Pacific. Thus, if time permits, we are planning to drill shallow holes (410 m) on the southern slope of the southernmost Okinawa Trough. The main objective is to study the Pleistocene history of the Kuroshio Current on glacial-interglacial and millennial time scales.

A long record of the Kuroshio Current of the past 2 m.y. will offer a unique opportunity to study the roles of the Kuroshio in relation to sea-level fluctuation, global climatic variation, local tectonic development, and terrestrial environmental changes in East Asia at different time scales. The Kuroshiro Current site is designed to: (1) identify patterns of long-term climate change associated with the western Pacific boundary current during the past 2.0 m.y.; (2) examine the western Pacific component of long-term changes due to orbital forcing in the mid-Pleistocene (0.7 Ma) when Earth's climate system switched from a regime of dominant 41-k.y. cycles to 100-k.y. cycles; (3) explore any long-term El Niño/La Niña type of climate oscillation in the low-latitude Pacific over the late Pleistocene glacial-interglacial cycles by comparing the Kuroshio record to other Pacific ODP records; and (4) document the temporal and spatial variability of millennial climate changes in the Kuroshio.

The proposed drilling Site KS-1 is located at 24°48.24'N, 122°30.00'E in 1270 m deep water at the intersection of three seismic reflection profiles shot by the R/VM Ewing in 1995 (Fig. 11). The selection of this site is based on data collected recently during several international cooperative programs and multidisciplinary integrated programs such as Kuroshio Edge Exchange Processes (KEEP) and Southernmost Part of Okinawa Trough (SPOT) (Lee et al., 1998).

Drilling Strategy | Table of Contents