Early-diagenetic carbonate concretions are the product of localized mineral precipitation from alkaline pore fluids migrating through soft and still not compacted sediments. The cementation produces a rigid, compaction-resistant framework that prevents mechanical and chemical destruction of primary biotic and sedimentary features. Therefore, such rocks represent containers of paleoenvironmental data enabling reliable and detailed reconstruction of the depositional and environmental settings, especially in cold seeps, where carbonate precipitation is fostered by oxidation of methane. Concretions are often associated with ichnofossils, i.e. traces of past benthic activity becoming preserved, in particular when authigenic minerals precipitated within and/or around burrows. Moreover, concretionary cements are key archives of past biogeochemical reactions and fluid composition shallow in sediment. Despite extensive research, many fundamental issues regarding the relationship between bioirrigation and concretion formation remain poorly addressed. The main goal of this PhD project is to investigate the mutual relationship between benthic activity, fluid circulation, fluid composition, and biogeochemical processes taking place close to the sediment-water interface at ancient cold seeps.
Research material collected during several fieldwork campaigns will be studied with the use of quantitative X-ray diffractometry, optical microscopy, cathodoluminescence microscopy, scanning electron microscopy, electron probe microanalysis, computed microtomography, and δ13C and δ18O analyses. These standard methods will be the foundations for basic considerations and for the selection of samples for advanced geochemical investigations. U-Pb dating of carbonate cements will constrain the timing of the consecutive stages of carbonate precipitation and durability of burrow-derived fluid conduits. In-situ C and O isotope measurements using ion microprobe will be employed to understand the influence of bioturbational structures and associated mucus lining on the precipitation of carbonate cements around them.
Bioirrigation in cold seeps plays an important role in regulating emissions of methane, which is a much more efficient greenhouse gas than CO2. Yet, burrowing organisms are susceptible to environmental conditions at the seafloor. Abrupt climate-induced changes of these conditions modify abundance and diversity of benthic biota, which in turn affect fluid circulation. This project offers a comprehensive, interdisciplinary research on seep carbonates through ichnological, mineralogical, petrographic, and geochemical investigations, which is designed to recognize the interplay between biota, environmental parameters, and carbonate precipitation and their possible impact on paleoclimate.
Project acronym: “Ichnocretions”
Funding source: National Science Centre (NCN), OPUS 27 Programme
NCN project title: Carbonate ichnocretions as a record of the interaction between benthic activity, fluid circulation and biogeochemical processes taking place in marine clastic sediments
Principal investigator: Dr. hab. Maciej Bojanowski (e-mail: mbojan@twarda.pan.pl)
Scientific supervisor: Dr. hab. Maciej Bojanowski, Prof. Dr. Andreas Wetzel
Project summary:
Application deadline: 10.02.2025
Announcement of recruitment results: until 10.03.2025
Start of the employment: 1.04.2025
Duration of the employment: 48 months
Remuneration: gross-gross 5 000 PLN/month (ca. net 3800 PLN) during the first 24 months, gross-gross 6500 PLN/month (ca. net 5000 PLN) during the next 24 months
Location: Institute of Geological Sciences, Polish Academy of Sciences, Warsaw, Poland
We offer:
Please note that apart from basic scholarship there is a variety of possibilities to increase the amount of your scholarship by applying for internal and external grants. Please discuss this issue with your supervisor.
Please be aware that the Institute of Geological Sciences does not participate in costs of your relocation to Poland and settling down here. Therefore you should be financially prepared to cover the travelling costs, renting a flat/room and for living for a few weeks until first money will top up your Polish account (we try to be as fast as possible, but we cannot overcome unexpected administrative problems).
Requirements / Expectations:
Duties / Responsibilities:
Form of submitting documents:
Applications should be submitted in one PDF file to rekrutacja_ingpan@twarda.pan.pl and to the principal investigator of the project, Dr. hab. Maciej Bojanowski: mbojan@twarda.pan.pl. In the title of the message, please indicate the acronym "Ichnocretions". For additional information please contact:
Dr. hab. Edyta Zawisza – Coordinator of the GeoPlanet Doctoral School: ezawisza@twarda.pan.pl
Dr. hab. Maciej Bojanowski – Principal investigator of the project: mbojan@twarda.pan.pl