Sedimentology, Stratigraphy and Palaeoenvironments

How, and why, have Earth's surface environments and climates varied over geological time? 

Much of the research in Oxford in sedimentology and stratigraphy is motivated by this question and the desire to understand Earth history. We apply geochemical proxies for climate and environments to the sedimentary record and, consequently, need to understand depositional and diagenetic processes as well as the spatial and geographic context of our study sites; thus, our research covers many broad aspects of sedimentology and stratigraphy but all with a general focus on reconstructing environmental and climatic change in the geological past. Between us we have worked on geological time periods spanning from the Precambrian to the Quaternary. A related area of research is the nature of bias in the sedimentary record due to depositional, and, in particular, preservational processes. 

We work closely with other research groups and themes in Oxford, including Palaeobiology, Noble Gas, Volcanology, Physical Oceanography. and Earth Resources.

Past DPhil students and PDRAs

Dr Sietske Batenburg

Dr Alex Dickson

Dr Brooke Johnson

Dr James Lucas

Dr Tin Tin Naing

Dr Charlotte O’Brien

Dr Lauren O’Connor

Dr Micha Ruhl

Dr James Scaife

Dr Ritwika Sengupta

Dr Marisa Storm

Dr Tim Sweere

Dr Weimu Xu

 

 

Research focus: warm climates of the past

Over the last 540 million years, Earth has, for long intervals of time, lacked large ice sheets like those we see today on Greenland and Antarctica. Warmer intervals in Earth history are called “greenhouse” climates and were characterised by a lack of polar ice, the presence of tropical and sub-tropical floras and faunas at high latitudes and low equator-to-pole temperature gradients.

The most recent greenhouse period of Earth history occurred during the Mesozoic and early Cenozoic, and is the focus for research at Oxford. This interval of time is also characterised by geologically brief perturbations of the carbon cycle such as the ‘oceanic anoxic events’ (OAEs) and the hyperthermals of the early Cenozoic (including the Paleocene–Eocene Thermal Maximum, PETM). Such greenhouse intervals of time provide insights into Earth’s natural climate variability, climate sensitivity to CO2. Furthermore, the late Mesozoic and early Cenozoic were important intervals in the early evolution and radiation of key aspects of modern ecosystems, including the flowering plants, and siliceous and calcareous phytoplankton.

We seek to address questions such as…

  • How warm was the greenhouse world?
  • Was there significant polar ice during the time of the Mesozoic greenhouse?
  • How and where did deep-water masses form?
  • How did the hydrological cycle operate?
  • What triggered OAEs and hyperthermals and how did they affect ocean chemistry and environments?
  • How rapid was carbon-cycle and climate change during OAEs?

Current research includes a NERC-funded collaboration ("PaleoGradPhan") with Professors Helen Johnson (Oxford Earth Sciences), Dan Lunt (University of Bristol) and Paul Valdes on the mechanisms by which latitudinal climate gradients changed over the Phanerozoic.

Techniques and facilities we use

The group uses a broad range of techniques to study sediments, including optical microscopy, SEM and geochemistry. Much of our geochemical work is focused on the application and development of inorganic and organic proxies for past climatic, oceanographic and environmental conditions (including stable isotopes, organic biomarkers, bulk organic geochemistry, elemental concentrations and metal-isotopes). We often collaborate with other groups and laboratories, including the Department's geochemical laboratories, clean-suite facilities, e-beam labs and geofacilities. You can find out more about our capabilities on the Research Facilities webpage.

In addition to the facilities hosted by the Department, we also oversee facilities for solvent extraction of organic molecules and for analysing organic matter by Rock-Eval 6 and GC/MS.