Previous   |    Next

doi:10.2204/iodp.proc.342.201.2017

Introduction

A robust record of the regional variation in biogenic sediment accumulation rates is needed to understand how climatic and oceanic changes through the Cenozoic may have affected biological productivity and export processes and to better resolve the relationships between climate change and the global carbon cycle. Biogenic opal is a widely used proxy for primary production (e.g., Moore et al., 2008) but is often hard to reliably distinguish from other sources of silica in hemipelagic sediments. Moreover, biogenic silica accumulation is a function of nutrient availability and opal preservation on the seafloor, both of which may vary independently over time (Moore et al., 2014). As with all proxies, it is inadvisable to use this proxy in isolation. Biogenic silica accumulation rate may prove to be a complementary guide to productivity when combined with other proxies, such as trace element geochemistry and benthic foraminifers.

This report combines shipboard data from smear slides with shipboard and shore-based data from radiolarian micropaleontology to provide a general guide to the occurrence and abundance of siliceous microfossils (radiolarians and diatoms) in the cores recovered during Integrated Ocean Drilling Program (IODP) Expedition 342 (see the “Expedition 342 summary” chapter [Norris et al., 2014b]). Expedition 342 investigated the Cretaceous–Cenozoic ocean history of the northwest Atlantic (latitude ~41˚N) through the recovery of expanded sequences of sedimentary drift deposits deposited in the flanks of J-Anomaly and southeast Newfoundland Ridges (Fig. F1). It is hoped that this overview will improve our understanding of the general controls on biosiliceous sedimentation in this region through the Cenozoic and serve to guide future studies into trends in biogenic sediment accumulation patterns.

The correlation with radiolarian zones has also been reviewed and updated for Sites U1403–U1410 (Figs. F2, F3, F4, F5, F6, F7, F8, F9).

Top of page   |    Previous   |    Next