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Overview

The Indian Monsoon (a subsystem of the Asian Monsoon) is one of the best examples of coupling between solid Earth and atmospheric processes. Its evolution during the late Pliocene (~3.5–2.5 Ma), when Earth witnessed dynamic global change as a result of the intensification of Northern Hemisphere Glaciation (NHG) and significant reduction in CO2, is poorly constrained. Although changes in the intensity of the Asian monsoon have been linked to the NHG from terrestrial records [1, 2], a clear association has not yet been demonstrated. This project will apply multi-proxy methods to reconstruct vegetation, aridity and monsoon runoff records for the Plio-Pleistocene transition from the core monsoon region of the Bay of Bengal (BoB). These records will address the key question: how were vegetation, aridity (related to northeast monsoon) and Indian summer monsoon runoff linked before, during and after the onset of NHG? The new Indian monsoon records from this project will be compared with published terrestrial records from northern Tibet [2] to identify the nature of the linkage between the Indian and Asian Monsoons. Further comparison of the timing of significant change in the Indian monsoon and active uplift of northern Tibetan plateau in the NE during the Plio-Pleistocene transition [1] will provide valuable information about the linkages between tectonics and monsoon evolution. 

This project will primarily use newly drilled continuous sedimentary successions from the BoB (IODP Expedition 353, Sites U1444 and U1445). Additional legacy samples (from ODP Site 758) may also be included if required to answer key scientific questions.   

The student will reconstruct past environmental change during the onset of the NHG at ~4 kyr resolution, focusing on the following parameters:

  • vegetation history using fossil pollens and spores
  • macro and micro-charcoal abundances
  • bulk sediment/carbonate elemental and organic carbon compositions
Critical regions of monsoon precipitation [1]. This project will analyse samples from the Bay of Bengal (IODP Exp. 353, Sites U1444 and U1445) and compare data from the Indus Fan (IODP Exp. 355) and IODP site 1148 in the north China Sea site [3].

Methodology

Macro-charcoal (>180 mm), microfossils, pollens, micro-charcoal and spores will be extracted from different size fractions of the deep-sea samples in the fully equipped laboratories at The Open University using acid digestion techniques, and will be examined and classified using transmitted light microscopy.

Bulk sediment XRF and geochemical work (carbonate oxygen and carbon, total organic carbon and nitrogen isotopes measurements) will be analysed on another split of the same sample. Coupled palynological and bulk sediment elemental composition records will be utilised to infer changes in vegetation on land and runoff due to monsoon variation. Detailed charcoal work will be carried out to reconstruct fire history. 

Training and Skills

The student will gain experience in a wide variety of laboratory techniques including deep-sea sample processing, palynology (pollen identification; Dr Bhagwat and Dr Mander) and geochemical techniques (stable oxygen and carbon isotopes and bulk sediment) at the state of the art facilities at The Open University. In addition, the student will receive specific training on charcoal work (Dr. Belcher) and stratigraphy and comparison with organic (Dr Littler) and siliceous microfossils (Dr. Romero) proxies. Finally the monsoon records will be placed in context with Plio-Pleistocene tectonics and climate.

CENTA students will attend 45 days training throughout their PhD including a 10-day placement. In the first year, students will be trained as a single cohort on environmental science, research methods and core skills. Throughout the PhD, training will progress from core skill sets to master classes specific to the student's projects and themes. 

Through the project partnership all relevant training will be provided in well-equipped labs. Specific skills that will be acquired during this project include:

  • Conducting research on newly discovered deep-sea sediments (IODP Expedition 353) and working with an international team
  • Palynology 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-supervise on your own devised OU’s master’s project and online teaching opportunities via the Open University Virtual Learning Environment are also available, including teaching on the new Massive Open Online Courses (MOOCs).

Timeline

Year 1: Obtain training in sample processing of core material for palynology (taxonomy), inorganic geochemical and light isotope techniques. Generate pxrf data from Sites U1445 and U1444 and process samples to generate a vegetation change record using elemental data. Attend UK IODP workshop and present results at the Exp 353 Science meeting in India.

Year 2: Present elemental results at IODP and Geochemistry Research in Progress meetings and prepare manuscripts. Generate vegetation and aridity records from two sites. Two week-long placement learning field work/other skills. Carry out statistical analyses of generated data set and draft one manuscript. Present results at Geochemistry Group Research in Progress meeting and international conference.  

Year 3–3.5: Finish remaining analytical work, data analyses, and present results at an international conference and write up thesis and manuscripts. 

Partners and collaboration (including CASE)

This project will benefit from international collaborations and networking opportunities with IODP 353 expedition scientists. In particular there will be collaboration with co-chief scientists Steve Clemens (USA) and Wolfgang Kuhnt (Germany) and scientists working on the Plio-Pleistocene transition for stratigraphy (Marci Robinson, USGS), grain size and tectonics (Priyank Jaiswal, OSU, USA) and productivity proxies (Oscar Romero, MARUM, Germany). 

Further Details

Students should have an interest in earth system processes, and enthusiasm for learning new proxies and their application in palaeoclimate. The student will join a well-established team researching palaeoenvironmental change at the Open University and Exeter University.

Please contact Dr Pallavi Anand (Pallavi.anand@open.ac.uk) for further information.