Quantifying marine redox during the Triassic–Jurassic mass extinction

This project is available from the academic year 2020/21 onwards.

Theme: Past Life & Environments

Primary Supervisor:

Alex Dickson

Department of Earth Sciences, RHUL

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Secondary Supervisor:

Martin King

Department of Earth Sciences, RHUL

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Project Description:

The Triassic–Jurassic boundary event, c.201.5 million years ago, coincided with one of the largest mass extinctions in Earth’s history. It also occurred during the largest volcanic event of the Phanerozoic, the Central Atlantic Magmatic Province, which was directly associated with the breakup of Pangaea, the formation of an ancestral Atlantic Ocean, and significant perturbations in the global carbon cycle. Numerous mechanisms have been proposed to account for the Triassic–Jurassic mass extinction, including the spread of low-oxygen marine water masses onto shallow continental shelves, that subsequently became poisonous to marine life. However, three problems currently exist with this model: firstly, the timing of de-oxygenation relative to the mass extinction event is not well understood; secondly, the heterogeneity in the timing of de-oxygenation at different locations is not well constrained; and thirdly the prevalence (or not) of de-oxygenation in the deep ocean is relatively unknown.

This PhD project will attempt to answer some of the questions posed above. The student will use the isotopic composition of molybdenum and cadmium in organic-rich mudrocks and carbonates to reconstruct the pattern and magnitude of redox change in the oceans across an interval of the Late Triassic to Early Jurassic. They will use samples from a variety of locations across the world, some of which will need to be obtained through fieldwork to South and/or North America and Europe. The student will also receive training in the preparation of geological samples for isotopic measurements, and in the mass-spectrometry techniques required to produce these data.

Policy Impact of Research:

Understanding the effects of rapid climate change on the marine environment is a critical challenge for predicting the effects of future deoxygenation on marine ecology and ecosystems. By elucidating the pattern of marine redox change during one of the most profound episodes of rapid environmental change of the past 250 million years, this project will help to address this challenge.

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