Project highlights

  • Reconstruct first orbital-resolution Pliocene Indian monsoon dynamics
  • Training in multi-proxy geochemical and micropaleontological reconstructions
  • International collaboration with IODP expedition scientists.

Overview

The Indian Monsoon (IM) precipitation is the main seasonal driver of water availability, supporting billions of people. The future projection of mean annual ISM rainfall is highly variable under different warming scenarios and an increase in the frequency of extreme precipitation has been suggested if global mean temperature increases ≥ 3 °C1. Our ongoing proxy and modelling work suggest multiple competing controls on IM dynamics (precipitation and wind) during the Plio-Pleistocene linked to atmospheric carbon dioxide (CO2), global cooling, orbital forcing factors and gateway closure2. Nevertheless, the past evolution of IM remains elusive since it is grossly under-represented in Asian monsoon palaeoclimate proxy records. This project aims to produce new proxy records to test competing forcing factors affecting IM dynamics during the early to mid-Pliocene (3 to 5 Ma), capturing the prevailing warm, high atmospheric CO2 conditions and gateway closure3.

This project will apply a multi-proxy approach to reconstruct ISM rainfall/runoff, seasonality of monsoon rainfall/runoff and marine productivity in response to ISM wind variability (by collecting pollen data) on orbital timescales from the core ISM region of the Bay of Bengal (BoB). The selected International Ocean Discovery Programme (IODP) sites boasts from X-Ray Fluorescence (XRF) elemental ratios and foraminifera assemblage data (collaborator Robinson).  New records from this project will be compared with published monsoon and climate records to identify the nature of the linkage between Asian Monsoon subsystems and global climate. This project will primarily utilise continuous sedimentary successions from the BoB (IODP Expedition 353, Sites U1444, U1445 and U1443 and legacy ODP site 722 in the Arabian Sea) to address some of the key questions: what is the response of ISM dynamics during the evolving boundary conditions of early- and mid-Pliocene? How are ISM dynamics linked to the other tropical monsoon regions?

Graphic showing wind and rainfall in monsoon in Northern hemisphere regions in summer and winter
Figure 1: Modern rainfall superimposed with wind stress in Asia during the northern hemisphere summer and winter showing different monsoon regions (modified after Wang et al., 2003). Samples are available from IODP Exp 353 Sites (yellow stars) and ODP site 722 (blue star) for this project.

Host

The Open University

Theme

  • Dynamic Earth

Supervisors

Project investigator

Pallavi Anand, The Open University ([email protected])

Co-investigators

  • Kate Littler, University of Exeter
  • Phil Holden, The Open University
  • Clara Bolton, CEREGE
  • Mel Leng, BGS
  • Marci Robinson, USGS
  • Masafumi Murayama, Kochi University, Japan

How to apply

Methodology

The deep-sea mud samples will be washed and the coarse fraction (>150 mm) will be used for picking foraminifera for geochemical work (oxygen and carbon isotopes measurements) and investigating pollen from the same sample in the fully equipped laboratories at The Open University. Benthic foraminifer oxygen isotope measurements will be used to extend the ongoing work on Pliocene stratigraphy (to the early Pliocene). The study sites already have XRF scanned bulk sediment geochemical data which will be coupled with coccolithophore and foraminifera assemblage data (in collaboration) to infer changes in surface water stratification, productivity and runoff in response to variability in monsoon dynamics. Further, targeted intervals will be used for multi-species planktic foraminifera geochemical (coupled trace element and oxygen isotope) data to reconstruct ISM runoff and pollen data for continental vegetation and wind strength. Additionally, multi-proxy data will be utilised to infer orbital and/or seasonal scale variations in rainfall/runoff and wind strength to be put in context with model output4. The project offers a variety of proxies exploration depending upon candidate’s interest.

Training and skills

Students will be awarded CENTA2 Training Credits (CTCs) for participation in CENTA2-provided and ‘free choice’ external training. One CTC equates to 1⁄2 day session and students must accrue 100 CTCs across the three years of their PhD.

In addition, the student will receive specific training on coccolithophore assemblage data collection and interpretation from Dr Bolton (at CEREGE) and work closely with collaborators.

The student will receive project specific training with supervisors (PA and PBH) and additional OU training.

Specific skills that will be acquired during this project include:

  • Foraminifera taxonomy and geochemical analyses
  • Data handling and interpretation from a wide variety of sources
  • Scientific communication through writing, poster and oral presentations to academic and non-academic audiences
  • Co-supervision on your own devised OU’s master’s project and teaching research methods to A level Nuffield funded summer students.

Partners and collaboration

This project will benefit from international collaborations and networking opportunities with IODP 353 expedition scientists. In particular, there will be collaboration with scientists working on the Pliocene for stratigraphy, foraminifera assemblage (Marci Robinson, USGS) and productivity proxies (Emmeline Gray, OU).

Further details

If you wish to apply to the project, applications should include:

  • A CV with the names of at least two referees (preferably three and who can comment on your academic abilities)

Applications to be received by the end of the day on Wednesday 11th January 2023.

 

Possible timeline

Year 1

Obtain training in sample processing of core material for microfossils (taxonomy), inorganic geochemical and stable isotope techniques. Generate benthic oxygen isotope stratigraphy and collate coccolithophore productivity data and interpret together with existing XRF data. Present at UK-IODP annual meeting.

Year 2

Prepare a manuscript based on age model, productivity and XRF data. Generate planktic geochemical data to support preliminary observations (yr 1) from the BoB sites. Present geochemical data at the Geochemistry Research in Progress meeting or Palaeopercs seminar.

Year 3

Carry out data-motel integration work after remaining data analyses, and present results at an international conference and write up thesis and manuscripts.

Further reading

  1. Bhowmick, M. Sahany, S., and Mishra, S. K. (2019) Projected precipitation changes over the south Asian region for every 0.5C increase in global warming, Environmental Research Letters, 14, https://doi.org/10.1088/1748-9326/ab1271.
  2. Thomson., , Holden P., Anand, P., Harris, NWB, Porchier, C, and Edwards, N. (2021) Tectonic and climatic drivers of the Asian Monsoon evolution, Nature Communications, 4022 (12), doi.org/10.1038/s41467-021-24244-z
  3. Dowsett, H. J., Robinson, M. M., Stoll, D. K., Foley, K. M., Johnson, A. L. A., Williams, M. and Riesselman, C.R. (2013) The PRISM (Pliocene palaeoclimate) reconstruction: time for a paradigm shift, Philosophical Transaction of Royal Society, 371, p. 20120524
  4. Nilsson-Kerr, K., Anand, P., Holden, P. B., Leng, M. J., and Clemens, S.C. (2021) Dipole patterns in tropical precipitation were pervasive across landmasses throughout Marine Isotope Stage 5, Communications Earth and Environment, 2, doi.org/10.1038/s43247-021-00133-7

COVID-19

We will have a binocular microscope available for student to work from home. Lab protocols video will be available for online training and support via skype/teams. Also, we have a proven online method for training student for foraminifera taxonomy which we will continue to use for training if covid restrictions continue. The project boasts from availability of washed samples, equipment/microscope to take home and online training for washing and taxonomy, providing mitigations for covid restrictions. Once the samples are picked, it will be delivered for oxygen isotope measurements at the British Geological Survey following OU risk assessment for travel.