A5039460564- Paleontology and Stratigraphy of Fossils
- Marine and coastal ecosystems
- Methane Hydrates and Related Phenomena
- Microbial Community Ecology and Physiology
- Geochemistry and Elemental Analysis
- Geology and Paleoclimatology Research
- Atmospheric and Environmental Gas Dynamics
- Marine Biology and Ecology Research
- Hydrocarbon exploration and reservoir analysis
- Geological and Geochemical Analysis
- Protist diversity and phylogeny
- Metallurgy and Cultural Artifacts
- Origins and Evolution of Life
- Geological Studies and Exploration
- Marine Bivalve and Aquaculture Studies
- Geophysics and Gravity Measurements
- Marine and environmental studies
- Biocrusts and Microbial Ecology
- Cephalopods and Marine Biology
- Groundwater and Isotope Geochemistry
- Genomics and Phylogenetic Studies
- Archaeology and Historical Studies
- Earth Systems and Cosmic Evolution
- Radioactivity and Radon Measurements
- Astro and Planetary Science
University of Exeter
2014-2024
Ocean acidification and mass extinction The largest in Earth's history occurred at the Permian-Triassic boundary 252 million years ago. Several ideas have been proposed for what devastated marine life, but scant direct evidence exists. Clarkson et al. measured boron isotopes across this period as a highly sensitive proxy seawater pH. It appears that, although oceans buffered acidifiying effects of carbon release from contemporary pulses volcanism, buffering failed when volcanism increased...
The progressive oxygenation of the Earth's atmosphere was pivotal to evolution life, but puzzle when and how atmospheric oxygen (O2) first approached modern levels (∼21%) remains unresolved. Redox proxy data indicate deep oceans were oxygenated during 435-392 Ma, appearance fossil charcoal indicates O2 >15-17% by 420-400 Ma. However, existing models have failed predict at this time. Here we show that earliest plants, which colonized land surface from ∼470 Ma onward, responsible for...
Abstract The nature of the last universal common ancestor (LUCA), its age and impact on Earth system have been subject vigorous debate across diverse disciplines, often based disparate data methods. Age estimates for LUCA are usually fossil record, varying with every reinterpretation. LUCA’s metabolism has proven equally contentious, some attributing all core metabolisms to LUCA, whereas others reconstruct a simpler life form dependent geochemistry. Here we infer that lived ~4.2 Ga...
It is unclear why atmospheric oxygen remained trapped at low levels for more than 1.5 billion years following the Paleoproterozoic Great Oxidation Event. Here, we use models erosion, weathering and biogeochemical cycling to show that this can be explained by tectonic recycling of previously accumulated sedimentary organic carbon, combined with sensitivity oxidative weathering. Our results indicate a strong negative feedback regime when concentration order pO
The controls on the 'Redfield' N : P stoichiometry of marine phytoplankton and hence ratio deep ocean remain incompletely understood. Here, we use a model for ecophysiology growth, based functional traits resource-allocation trade-offs, to show how environmental filtering, biotic interactions, element cycling in global ecosystem determine biogeography, growth strategies macromolecular composition. Emergent capture major observed patterns biomes. Using new synthesis experimental RNA protein...
Abstract Tectonic drivers of degassing and weathering processes are key long‐term controls on atmospheric CO 2 . However, there is considerable debate over the changing relative importance different carbon sources sinks. Existing geochemical models have tended to rely indirect methods derive tectonic drivers, such as inversion seawater 87 Sr/ 86 Sr curve estimate uplift or continental basalt area. Here we use improving geologic data update representation in COPSE biogeochemical model. The...
A 'Neoproterozoic oxygenation event' is widely invoked as a causal factor in animal evolution, and often attributed to abiotic causes such post-glacial pulses of phosphorus weathering. However, recent evidence suggests series transient ocean events ∼660-520 Ma, which do not fit the simple model monotonic rise atmospheric oxygen (pO2). Hence, we consider mechanisms by evolution marine eukaryotes, coupled with biogeochemical ecological feedbacks, potentially between alternate stable states,...
Here we describe a new trait‐based model for cellular resource allocation that use to investigate the relative importance of different drivers small cell size in phytoplankton. Using model, show increased investment nonscalable structural components with decreasing leads trade‐off between size, nutrient and light affinity, growth rate. Within most extreme nutrient‐limited, stratified environments, competition theory then predicts trend toward larger minimum increasing depth. We demonstrate...
The balance of evidence suggests that oxygenic photosynthesis had evolved by 3.0–2.7 Ga, several hundred million years prior to the Great Oxidation ≈2.4 Ga. Previous work has shown if spread globally Oxidation, this could have supported widespread aerobic ecosystems in surface ocean, without oxidising atmosphere. Here we use a suite models explore implications for carbon cycling and Oxidation. We find recycling oxygen within early marine would restricted balanced fluxes methane escaping from...
Abstract. We present the first version of OMEN-SED (Organic Matter ENabled SEDiment model), a new, one-dimensional analytical early diagenetic model resolving organic matter cycling and associated biogeochemical dynamics in marine sediments designed to be coupled Earth system models. explicitly describes (OM) most important terminal electron acceptors (i.e. O2 , NO3, SO4) methane (CH4), related reduced substances (NH4, H2S), macronutrients (PO4) pore water quantities (ALK, DIC). Its reaction...
ABSTRACT In order to assess observational evidence for potential atmospheric biosignatures on exoplanets, it will be essential test whether spectral fingerprints from multiple gases can explained by abiotic or biotic-only processes. Here, we develop and apply a coupled 1D atmosphere-ocean-ecosystem model understand how primitive biospheres, which exploit sources of H$_2$, CO, O$_2$, could influence the composition rocky terrestrial exoplanets. We this Earth at 3.8 Ga TRAPPIST-1e. focus...
Abstract. Drilling for the International Continental Scientific Program (ICDP) Early Jurassic Earth System and Timescale project (JET) was undertaken between October 2020 January 2021. The drill site is situated in a small-scale synformal basin of latest Triassic to age that formed above major Permian–Triassic half-graben system Cheshire Basin. borehole located recover an expanded complete succession complement legacy core from Llanbedr (Mochras Farm) drilled through 1967–1969 on edge...
With the characterisations of potentially habitable planetary atmospheres on horizon, search for biosignatures is set to become a major area research in coming decades. To understand atmospheric characteristics that might indicate alien life we must abiotic planet and how interacts with its environment. In field biogeochemistry, sophisticated models life-environment coupled systems demonstrate many assumptions specific Earth-based life, e.g. ATP maintenance costs, are unnecessary accurately...
Methane is thought to have been an important greenhouse gas during the Archean, although its potential warming has found be limited at high concentrations due shortwave absorption. We use Met Office Unified Model, a general circulation model, further explore climatic effect of different Archean methane concentrations. Surface peaks pressure ratio CH$_4$:CO$_2$ approximately 0.1, reaching maximum up 7 K before significant cooling above this ratio. Equator-to-pole temperature differences also...
The co-evolution of life and environment is a dynamic system feedbacks. Much the evolution took place in localized shelf sea environments where evolving biota redox conditions created feedbacks which are hypothesized to have increased ecospace for radiate - sometimes perhaps brought about its own demise. Models can suggest hypotheses test ecosystem dynamics effects changes or on other. A particular modelling challenge connect these global Earth over long timescales. hierarchy models needed...