Did you say ‘fast’? Early diagenetic modification of climatic signals in lacustrine sediments (Advert Reference: RDF21/EE/GES/KWIECIENOla)

Semiarid regions are disproportionally responsive to the impact of anthropogenic climate change and credible projections of water availability in global warming scenarios rely on an accurate recording and understanding of past climate change. Yet, climate reconstructions are only as reliable as the validity of the assumptions and the quality of the proxies applied. Isotopic composition of carbonates from alkaline lakes (modern and ancient) is a common climate proxy in semiarid regions, but while carbonates from these lakes display variable mineralogical composition, their nature is only rarely verified in detail (McCormack et al. 2018; 2019). Working with sub-recent Lake Van sediments McCormack et al. (2018) have documented hitherto overlooked early diagenetic carbonate fractions and their impact on interpretation of sedimentary records. The early diagenetic fraction includes deep water, low temperature dolomite forming in the sediment pores, and aragonite encrustation of ostracod valves and organic remains. Diagenetic processes producing these carbonates take place ‘fast’ in terms of geological timescales (one of them likely within hours to days) but act selectively and their underlying mechanisms are not yet well understood. Addressing these issues calls for a wholistic approach to lacustrine carbonate system involving a combination of field data and geochemical modelling.

Lake Van, world’s largest alkaline lake, originated as a freshwater basin but transformed into alkaline water body early in its history. This project takes advantage of ICDP PALEOVAN legacy (Kwiecien et al., 2014) and aims at 1) systematic documentation of Lake Van carbonates, 2) resolving environmental factors leading to early diagenetic changes, 3) providing environmental narrative for the hydrological evolution of the world’s largest alkaline lake from its freshwater beginning ca 600 ka ago.

Successful candidate will work with already available pore water data and sediment samples, and perform analyses involving XRD, SEM, traditional stable isotope analyses (18O, 13C) on inorganic and biogenic carbonates, and state-of-the art Confocal Raman microscopy and clumped isotope geothermometry. Analytical results will be compared with those by geochemical modelling. The results of this study will provide unique insights into early carbonate diagenesis and, per extension, into strengths and limitations of carbonate-based lacustrine proxies. Additionally, this project will shed light on long-term evolution of alkaline lakes.

This PhD project offers unique opportunities for training in frontier isotope techniques, carbonate geochemistry and multi-proxy-based palaeolimnology. Our international team of geochemists and palaeolimnologists will provide mentoring, networking and dissemination possibilities through online meetings, conferences, and workshops.

We are looking for an enthusiastic, and focused candidate with a strong background in environmental sciences and a passion for discovery. Experience in carbonate sedimentology and chemistry would be advantageous.
The principal supervisor for this project is Dr. Ola Kwiecien.

Eligibility and How to Apply:
Please note eligibility requirement:
• Academic excellence of the proposed student i.e. 2:1 (or equivalent GPA from non-UK universities [preference for 1st class honours]); or a Masters (preference for Merit or above); or APEL evidence of substantial practitioner achievement.
• Appropriate IELTS score, if required.
• Applicants cannot apply for this funding if currently engaged in Doctoral study at Northumbria or elsewhere.

For further details of how to apply, entry requirements and the application form, see
https://www.northumbria.ac.uk/research/postgraduate-research-degrees/how-to-apply/

Please note: Applications that do not include a research proposal of approximately 1,000 words (not a copy of the advert), or that do not include the advert reference (RDF21/EE/GES/KWIECIENOla) will not be considered.
Deadline for applications: 29 January 2021
Start Date: 1 October 2021
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