Abstract
Abstract. Isotope stratigraphy has become the method of choice for investigating both past ocean temperatures and global ice volume. Lisiecki and Raymo (2005) published a stacked record of 57 globally distributed benthic δ18O records versus age (LR04 stack). In this study LR04 is compared to high-resolution records collected at all of the sites drilled during ODP Leg 154 on the Ceara Rise, in the western equatorial Atlantic Ocean. Newly developed software is used to check data splices of the Ceara Rise sites and better align out-of-splice data with in-splice data. Core images recovered from core table photos are depth and age scaled and greatly assist in the data analysis. The entire splices of ODP sites 925, 926, 927, 928 and 929 were reviewed. Most changes were minor although several were large enough to affect age models based on orbital tuning. A Ceara Rise composite record of benthic δ18O is out of sync with LR04 between 1.80 and 1.90 Ma, where LR04 exhibits two maxima but Ceara Rise data contain only one. The interval between 4.0 and 4.5 Ma in the Ceara Rise compilation is decidedly different from LR04, reflecting both the low amplitude of the signal over this interval and the limited amount of data available for the LR04 stack. A regional difference in benthic δ18O of 0.2 ‰ relative to LR04 was found. Independent tuning of Site 926 images and physical property data to the Laskar et al. (2004) orbital solution and integration of available benthic stable isotope data from the Ceara Rise provides a new regional reference section for the equatorial Atlantic covering the last 5 million years.
Highlights
Sedimentary archives retrieved by ocean drilling since 1968 by the Deep Sea Drilling Program (DSDP, 1968–1983), the Ocean Drilling Program (ODP, 1983–2003), the Integrated Ocean Drilling Program (IODP, 2003–2013) and the International Ocean Discovery Program (IODP, since 2013) provide key records needed to better understand processes and interactions of the Earth system
Sites drilled during ODP Leg 154 on the Ceara Rise have played a significant role in creating age models for the Neogene based on astrochronology
We have demonstrated a new system for capturing core images as data using newly developed CODD software
Summary
Sedimentary archives retrieved by ocean drilling since 1968 by the Deep Sea Drilling Program (DSDP, 1968–1983), the Ocean Drilling Program (ODP, 1983–2003), the Integrated Ocean Drilling Program (IODP, 2003–2013) and the International Ocean Discovery Program (IODP, since 2013) provide key records needed to better understand processes and interactions of the Earth system. Over almost 5 decades of coring, ocean drilling samples and data have contributed significantly to major breakthroughs in our understanding of Earth history – including such basic tenets as seafloor spreading, a detailed history of reversals of the Earth’s magnetic field and evolution/extinction of marine species. Included in this list is the advancement of stable isotope stratigraphy and the recognition of the critical part played by variations in the Earth’s orbital parameters in climate history. It has been demonstrated (e.g., Hays et al, 1976) that variations in 18O enrichment (δ18O) coincide with periodicities of the orbital parameters of eccentricity, obliquity, and precession and their influence on the distribution and in-
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