Scientific Webinars

What can novel mixed sand-mud bedforms tell us about cohesive sediment gravity flow behaviour in the fringe of submarine fans?

Megan Baker – University of Durham

Bedforms are a key tool to reconstruct sedimentary processes in modern and ancient environments. This talk will present novel mixed sand-mud bedforms which have different shapes and sizes compared to pure-sand bedforms, and are found in the fringe of submarine fans. These striking mixed sand-mud bedforms are interpreted to be produced by sediment gravity flows with transient-turbulent fluid dynamics, due to the presence of cohesive clay. The presence and spatial trends in mixed sand–mud bedform types may be an important tool in interpreting fan fringe environments.

A journey through tides in Earth’s History

Professor Mattias Green – Bangor University

The scientific endeavours of the Apollo Lunar missions provided two important, yet apparently contradictory, pieces of information. The lunar rock samples aged the Moon at 4.5Gy, whilst laser ranging measurements of present day lunar recession, facilitated by reflectors left on the Moon, imply an age of only 1.5Gy. It is evident that least one of these estimates must be wrong! We now know that Earth, because of its current continental configuration, has a very energetic tide. Because the dissipation of tidal energy act as a break on Earth’s rotation and thus forces the moon to recede, it is also a first order controller of lunar distance. Is it possible that the motion of continents has changed the tides enough on geological scales to facilitate a weaker tide that can reconcile the two age estimates of the moon? Here, I am hoping to answer this question by going on journey through Earth’s history and estimating the tidal energetics for a series of interesting time slices. I will also touch upon what the consequences may have been for other parts of the Earth system and for other planets.

Microplastics in sedimentary systems. What we know and don’t know about this new type of sediment particle

Dr Florian Pohl – Durham University

The threat posed by plastic pollution to ecosystems and human health is under increasing scrutiny and the amount of mismanaged plastic waste entering the environment is growing at a staggering rate. In particular microplastics (plastic particles <1 mm in size) have been discovered in every sedimentary system on the planet and thus became a new type of sediment particle. As such, sedimentology represents an important and powerful tool to understand and predict the transport, dispersal, and ultimate fate of microplastics in different environments. However, due to the complex shapes and low densities the transport and sedimentation behavior of this new sediment particle may differ significantly from those of natural sediments. The presence of microplastics in the environments poses new challenges for the field of sedimentology, but may also provide opportunities to better understand the dynamics of sedimentary systems. In this talk I will provide an overview on global plastic-pollution, microplastic as a new and unique sediment particle, and on microplastics in seafloor sediments.

Magnitude and drivers of short term sea level fluctuations in the Cretaceous: a review

Dr Franz van Buchem and Dr Andy Davies – Halliburton – Landmark

Based on a recent review of the literature a data base of absolute values of short term (<3my) Cretaceous sea level rises and falls has been created. This shows an overall amplitude range of 5 to >65m, organised in four broad trends. The potential of aquifer eustasy has been investigated using climate modelling which showed a maximum impact of 5 to 10 meters. This leaves Glacio-eustasy as the key driver for short term high magnitude sea level changes in the Cretaceous.

Building big bioherms from humble Halimeda: insights from a modern analogue

Mardi McNeil – Queensland University of Technology

The Halimeda algal bioherms of the Great Barrier Reef, Australia represent the largest living, actively accumulating Halimeda deposits worldwide. Following the Holocene post-glacial marine transgression, these bioherms kicked off the outer-shelf carbonate factory some 2000 years earlier than the nearby coral reefs. Recent multi-disciplinary work has revealed new insights into their surface geomorphology, subsurface architecture and depositional environment that may be of interest to those working on their fossil counterparts.