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James M Flaherty Research Scholarship 2018/19 Visit Report

Name:                              Dr Aoife Blowick

Home Institution:     National University of Ireland, Galway, Ireland.

Visited Institution:   Saint Mary’s University, Halifax, Nova Scotia, Canada.

Date of Visit:                1st-30th June 2019

Title of Research:
Pb isotopic fingerprinting of sands, offshore Nova Scotia: a novel approach to unravelling sand sources in the Scotian Basin

Field of Research:     Geoscience, provenance, geochemistry

 

Visit Details:

Research and development conducted:

Upon arrival, a meeting between all collaborators was held to review the results of the analysis completed to date. This meeting was key as it was the first face-to-face discussion of the results in which we took an in-depth look at specific results and their implications for the subsequent publication. In addition, it was an important opportunity for me to ask pertinent questions about previous work that my collaborators had completed that could potentially affect the interpretation of the results of the current study. At that a meeting, a plan for the following weeks was devised. Given the results collected to date and the retrieval of samples previously thought to be unavailable, it was decided that fieldwork to collect additional samples was no longer necessary and would simply incur unnecessary expense. Instead, it was agreed that the time would be better spent writing the first manuscript prior to my return, rather than afterward. The following weeks therefore involved continued discussion and collaboration on the first manuscript including the design of all figures and tables. As part of the write-up, screening of scanning electron microscopy (SEM) images was undertaken to characterise any link between the Pb isotopic composition of grains and their optical appearance.

My visit also involved a number of highly productive meetings discussing two additional future collaborations. The background for each project is given in the following section but for the purposes of describing activities undertaken during the visit the following is a short summary for each project.

For the first project, a small number of test samples had been analysed. Discussions therefore focussed on the implications of the results and how they would be used to produce a second publication written by myself and Dr Georgia Pe-Piper in the coming months. The preliminary results are sufficient for us to investigate further and additional samples are now being sought from other international collaborators elsewhere in Canada and the United States. During the visit, I wrote a summary of the Pb isotopic results acquired for the samples analysed to date which form part of the publication. Without these face-to-face discussions, continuing and expanding this collaboration would have been highly unlikely.

For the second project, discussion focused on the use samples collected by both Dr Pe-Piper and myself, from Canada, Ireland and beyond, to investigate the preservation of Pb isotopic fingerprints in authigenic grains (i.e. grains which grow after deposition by precipitation from pore fluids) and grains altered during burial and diagenesis. Hot cathodoluminescence imaging were used to identify most suitable samples for analysis in the Scotian Basin, whilst secondary electron images were used to identify potential samples from datasets I had previously analysed for Pb isotopes.

During my visit, I was hosted in the Geology Department at Saint Mary’s University and specifically within a postgraduate room. The benefit of this was that I was introduced to a number of postgraduate students all of whom where working on the Scotian Basin. As a result, one of the most rewarding aspects of the visit was discussions with these researchers, who by looking at different aspects of the basin, provided me with even more insight into the Canadian margin and its links to basins lying offshore of Ireland.

During my final week I visited the Bedford Institute of Oceanography (BIO) where I presented an hour-long overview on the uses, strengths and limitations of the Pb isotopic technique to over twenty researchers. As part of my visit I toured the facilities including the core store and had incredibly useful conversations with members of the Geological Survey, including a number of potential future collaborators.

 

Contacts made:

During my time in Halifax I was very fortunate to be introduced to a wide range of researchers both at Saint Mary’s University and the Bedford Institute of Oceanography (BIO). In particular, I met a number of researchers based at the Geological Survey of Canada at BIO which are important contacts for future research and employment opportunities.

Other notes:

I thoroughly enjoyed my visit and feel that it was critical to the success of the project and the production of a publication now submitted to one of the highest impact journals in geoscience. I also got to enjoy Canadian hospitality and learn about their culture, including their history of immigration, diversity, local artists and love for science.

Future/Continuing Collaboration (opportunities/plans):

Having successfully worked together on this project, there is immediate potential to collaborate on two new projects:

Project 1: Provenance of Athabasca Oil Sands:

The first project aims to investigate the sources and pathways of Alberta’s oil sands, the third largest oil reserve in the world. Previous provenance studies suggest that sand deposited ~115 million years ago in SW Alberta may have been supplied from as far east as Quebec and/or as far south as Texas. At the same time, in the Scotian Basin, offshore of Nova Scotia, there was a dramatic decline in the abundance of sand delivered to the offshore, suggesting that rivers were diverted away from the basin, most likely to the west or southwest. Hence this raises the question whether rivers previously draining to the Scotian Basin were diverted westward all the way to Alberta at this time, and whether Pb isotopic fingerprinting of K-feldspar can resolve this. Preliminary samples have been analysed and demand analysis of additional samples to resolve this issue. As such, a number of samples are being sought from additional collaborators. This work has important implications not just for the sources and pathways of the Alberta oil sands and therefore the evolution of the drainage network, but also the applications of specific provenance tools including U-Pb detrital zircon dating and Pb isotopic fingerprinting of K-feldspar. The project aims to produce at least one high-impact publication.

Project 2: Pb isotopic fingerprints of authigenic and diagenetically altered feldspar:

Again stemming from the research already undertaken in the Scotian Basin, this project aims to investigate the Pb isotopic composition of feldspar grains and overgrowths which have been altered or formed after burial. In particular, authigenic grains (i.e. grains formed after burial typically by precipitation from pore fluids) are important, and sometimes highly abundant features in sandstones around the world. In the Scotian Basin, the circulation of brines and subsequent alteration and loss of primary feldspars is well recorded. Using samples from the Scotian Basin in which altered grains and authigenic overgrowths have been previously identified by Dr Pe-Piper, we therefore aim to characterise the Pb isotopic composition of these grains and compare them to the Pb signatures of primary feldspar grains. This work is critical to refining the Pb-in-feldspar approach and will lead to at least one publication.

Conclusion:

My visit to Saint Mary’s University was highly productive and key to the continued and enhanced collaboration between researchers on either side of the Atlantic. As well as submitting the manuscript ahead of schedule, we now have plans for two additional projects, with one already started, demonstrating the usefulness of such a visit. In addition to the scientific aspect of my visit, I was also able to savour Canadian culture, explore the surrounding area of Halifax and create a network of contacts spanning both academic and governmental bodies.