Testing solid earth climate connections through mid ocean ridge time series

Introduction

A central problem of understanding the Earth system is quantifying climate-solid Earth feedback that requires time-series studies. One important time series is the climate (sea level) record that shows transitions between ice ages and warm periods for the last millions of years, involving vast mass transfer between continents (ice load) and oceans.

Volcanism and Glacial Cycles

Volcanism is sensitive to such pressure changes, but its response to glacial cycles is largely unknown for the global mid-ocean-ridge (MOR) system, where 80% of Earth's volcanism occurs. Models of MOR response to sea-level fluctuations predict changes in:

1. Crustal thickness
2. Chemistry of lavas
3. Hydrothermal activity

Challenges in Data Collection

Establishing high-resolution time series on MORs, however, has previously not been possible because the sea floor is rapidly covered by sediment as it moves away from the MOR and thus cannot be directly sampled.

Recent Advances

Recent studies, however, show that MOR eruptions deposit samples of lava as glass on nearby sediments for up to 100 ka. These carbonate-rich sediments can be precisely dated by oxygen isotope stratigraphy and provide an archive of:

• Ridge eruptions (glasses)
• Hydrothermal activity (trace metals)

These sediments can be sampled by gravity coring.

Proposed Methodology

Through closely spaced new cores to be retrieved during multiple research cruises, a high-resolution time series of volcanism and hydrothermal activity can be achieved and directly linked to the climate record. Additionally, seismic techniques can be used to determine variations in crustal thickness over time.

Objectives

We propose to obtain integrated data sets for all these processes from slow, intermediate, and fast spreading ridge segments over the past 1.5 Ma in unprecedented detail.

Expected Results

The results of these glass, sediment, and crustal thickness time series will allow us to unequivocally test the influence of glacial cycles on MOR processes and will provide the first high-resolution time series of ocean ridge magmatism, opening up a new frontier of scientific exploration.