Scientific Webinars

Join us as we explore the diverse world of Sedimentology. Drawing from a tranche of past BSRG talks and more, examples will be presented of sedimentary structures in ice and snow, the desert, the sky as well as more conventional settings. Prepare to be baffled by some real head scratchers and wowed by some of Earth’s largest ever structures, and finally head into space to speculate on the sedimentology of exoplanets.

Kathleen is a science team member for Mars 2020, This talk will give an overview of halite and gypsum on Mars and describe their potential to host microorganisms and organic compounds as solid inclusions and within fluid inclusions – as salt minerals on Earth do. The talk will place the search for life in salt minerals on Mars in context of the sample return plan for the Perseverance rover.

In the present day, Mars’ mid-to-high latitudes host abundant water ice within diverse and stunning glacial landscapes. In this talk, I will explore the recent history of glaciation and glacial meltwater on Mars, and discuss some of the morphological mysteries that remain.

During the webinar we shall report our recent studies to survey and sample the ultra-deep water hadal trenches that allow an unravelling the earthquake history of subduction zones and provide new insight into sediment mass and carbon transfer into the hadal trench – one of the least-explored sedimentary environments on our planet.

Strata may contain a signal that records the history of the tectonic and climatic forcing that controls how they form, and many conceptual models tie themselves in logical knots by assuming that these signals are always present in the strata. More interesting than assuming that a signal is present is testing what the signal might look like if it was present, and exploring how it can be extracted from the noise and autogenic patterns that may also be present. This presentation will show some results from numerical experiments using Lobyte3D, a simple stratigraphic forward model of a deep-water fan system, to investigate how an external signal is recorded, and how it can be distinguished, or not, from the autogenic patterns also present in the strata.

Geology has traditionally been a descriptive science with a significant portion of the data coming from observations of features at a range of scales. Modern practices in the oil industry still rely in a large part on this legacy of observational data, for instance when rock facies are used to derive regional stratigraphic trends from core data, or as a building block for petrophysical classifications. However, a recent study has shown that even experienced carbonate sedimentologists will often classify the same facies using different textural names. This problem is compounded in industry by large teams often collaborating on a project, resulting in a heterogeneous attribution of facies to similar rocks despite the use of a common classification scheme. This problem reduces the reliability of descriptive data. In this presentation, I will talk about our research applying machine learning to automatic identification of carbonate facies using the Dunham classification scheme. We used high-resolution core images from the Integrated Ocean Discovery Program (IODP) Leg 194. Core images are used to train a model written in the Python programming language using the TensorFlow machine learning library. Specifically, we used Google’s Inception V3 network as a pre-trained Convolutional Neural Network (CNNs), and applied a method called ‘transfer learning’ to train Inception V3 to recognize carbonate core images. Results show that our CNN can achieve up to 90% accuracy for identification of Mudstone to Rudstone and Crystalline Dolomite. The main misclassifications were between matrix and grain supported facies, and fine and coarse-grained facies, textures also commonly misclassified by control tests with geologists. Interestingly, the bias observed in core description by the algorithm is very similar to human biases: a tendency to give a greater weight to grains as they stand out from the matrix, called ‘saliency’. But the CNNs were able to identify facies 60 times faster than humans, and with a much greater consistency. The results of our study demonstrate the potential of artificial neural networks to reliably interpret and quantify descriptive data for the oil and gas industry, in a fast, automated, high-resolution manner. Current and future work will focus on acquiring a larger dataset of core and thin section images, improving the training of the neural network, and coupling image recognition with logging and petrophysical data estimation.

Two types of currents dominate sediment transport and deposition on continental slopes: sediment gravity flows that travel down the slope through submarine canyons, channels, and gullies; and bottom currents that are part of the ocean circulation and commonly flow along the slope. Continental slope morphologies reported from mixed sediment gravity flow – bottom current systems across the planet reflect various degrees of interaction between sediment gravity flows and bottom currents. Unfortunately, two communities of researchers have historically specialized in either gravity driven sediment transport or bottom current sediment transport. Consequently, the processes governing sediment transport and deposition in mixed systems are not clearly established and interpretations of mixed-system deposits in literature remain hypothetical and sometimes appear contradictory. In this seminar we will present the first measurements of combined contour-current and turbidity-current flows, which were obtained in laboratory experiments. The measurements demonstrate that contour currents flowing at 10 % of the turbidity current speed can pervasively deflect the turbidity current flow and prove for the first time that hybrid bottom-turbidity currents can be at the origin of asymmetric channel-levee systems. These first experiments are the starting point for discussions on the themes that need to be addressed by the deep water community to achieve an integrated understanding of sediment deposition in deep water environments by contour currents and turbidity currents.

Carbonate sedimentary rocks form through the accumulation of organisms and chemically precipitated calcium carbonate, usually on the sea floor. They preserve fragments of marine organisms, which are sensitive to temperature, salinity and seawater chemistry during their growth, and they therefore provide an exceptional record of evolutionary and climatic change through Earth’s history. Carbonate sediments are also highly reactive, dissolving and precipitating in surface water. For these reasons, despite their simple mineralogy, they have a reputation for being difficult to understand and many clastic sedimentologists approach them with caution! Nevertheless, carbonate sedimentary rocks are important for many reasons. They have been exploited for millenia for their minerals, water resources and, more recently, for cement, roadstone and hydrocarbon. Now, as we face the effects of climate change, we can use carbonate strata to understand how Earth responds to environmental stress and use this knowledge to better predict the effect of climate change on modern ecosystems. There is also growing interest in how carbonate sedimentary rocks can be used to good effect for carbon storage and geothermal heat production. This talk will provide an introduction to ‘novices’ of carbonate sedimentology to the principle processes that govern their formation and modification during lithification. It will illustrate their importance to our modern landscape and heritage and demonstrate how ancient carbonate systems can hold warnings, and solutions, to the effects of anthropogenic environmental impact.

“To see the World in a grain of sand… hold infinity in the palm of your hand and eternity in an hour” might be one of the best poetic descriptions for Luminescence Dating… sure, back in 1803, William Blake could not have imagined such scientific achievement! As a matter of fact, Optical Dating or OSL (Optically Stimulated Luminescence) has been one of the fastest growing dating methods since its development in 1985, in terms of protocol development, instrumentation and use. Who would have thought that a single ray of sunshine and the natural radioactive decay ever present in the environment would be allies for OSL signals to shine! As it uses two of the most abundant mineral grains available on the surface of the Earth (quartz & feldspars), OSL has a multitude of applications in addition to the ability to assign numerical ages to numerous environments and sedimentary deposits from the depths of the ocean to the highest peaks. In this presentation we will go over the basics of OSL Dating, and consider some of the major challenges, as well as the advantages. We will have a glimpse at the latest developments and applications, with a special focus on sedimentological and stratigraphical issues. One thing to bear in mind: OSL might not be used only for dating! The in-depth analysis of luminescence signals may give unforeseen insights into transport-deposition processes and events of both natural and anthropogenic origin.

If there were a guide book for the intergalactic sedimentologist then this would be the heavily-read chapter on terrestrial carbonates (principally those formed in soils, lakes, streams and springs). A reviewer might say that the examples used – although spanning a huge time range – are rather Earth-focussed. This largely reflects the travel budget of the author. But they would hopefully also say that this chapter is much more widely applicable to other planets, and that it contains beautiful pictures of all types of terrestrial carbonates. Readers would agree that hot-springs are great for holidays, but even the humble calcrete nodule can be invaluable for studying the co-evolution of life and environments on a planet.