IODP Proposal 626: "Cenozoic Equatorial Age Transect – Following the Palaeo-equator"

Pälike, H., Lyle, M.W., Moore, T.C., Mitchell, N.C., Backman, J., Rea, D.K. and Tauxe, L. (2004) IODP Proposal 626: "Cenozoic Equatorial Age Transect – Following the Palaeo-equator". Southampton, UK, University of Southampton, 48pp.


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As the largest ocean, the Pacific is intricately linked to major changes in the global climate system
that took place during the Cenozoic. Throughout the Cenozoic the Pacific plate has had a northward
component. Thus, the Pacific is unique, in that the thick sediment bulge of biogenic rich deposits
from the currently narrowly focused zone of equatorial upwelling is slowly moving away from the
equator. Hence, older sections are not deeply buried and can be recovered by drilling. Previous ODP
Legs 138 and 199 were designed as transects across the paleo-equator in order to study the changing
patterns of sediment deposition across equatorial regions, while this proposal aims to recover an
orthogonal “age-transect” along the paleo-equator. Both previous legs were remarkably successful in
giving us new insights into the workings of the climate and carbon system, productivity changes
across the zone of divergence, time dependent calcium carbonate dissolution, bio- and
magnetostratigraphy, the location of the ITCZ, and evolutionary patterns for times of climatic
change and upheaval. Together with older DSDP drilling in the eastern equatorial Pacific, both Legs
also helped to delineate the position of the paleo-equator and variations in sediment thickness from
approximately 150°W to 110°W.
As we have gained more information about the past movement of plates, and where in time “critical”
climate events are located, we now propose to drill an age-transect (“flow-line”) along the position
of the paleo-equator in the Pacific, targeting selected time-slices of interest where calcareous
sediments have been preserved best. Leg 199 enhanced our understanding of extreme changes of the
calcium carbonate compensation depth across major geological boundaries during the last 55 million
years. A very shallow CCD during most of the Paleogene makes it difficult to obtain well preserved
sediments, but we believe our siting strategy will allow us to drill the most promising sites and to
obtain a unique sedimentary biogenic carbonate archive for time periods just after the Paleocene-
Eocene boundary event, the Eocene cooling, the Eocene/Oligocene transition, the “one cold pole”
Oligocene, the Oligocene-Miocene transition, and the Miocene, contributing to the objectives of the
IODP Extreme Climates Initiative, and providing material that the previous legs were not able to

Item Type: Monograph (Project Report)
Additional Information: This document contains the original IODP Drilling Proposal 626Full2, and was submitted to the IODP in revised form in 2004.
Related URLs:
Subjects: Q Science > QE Geology
Divisions : University Structure - Pre August 2011 > School of Ocean & Earth Science (SOC/SOES)
ePrint ID: 46418
Accepted Date and Publication Date:
Date Deposited: 27 Jun 2007
Last Modified: 31 Mar 2016 12:21

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