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.
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.
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.
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.
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.
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.
The Cambrian Explosion marks the rise of diverse animal groups ca. 540 million years ago, but the triggers for this revolution remain poorly understood. The roots of the Cambrian Explosion are in to be found in the preceding Ediacaran, and we can now document a series of pulses of enhanced seawater oxygen stability over the Ediacaran to Cambrian interval. These coincide with pulses of diversification and increased body size in animals, and the biological control of carbonate production was driven by the rise of predation.
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.
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.
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.
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.