Lecture Programme

Lecture meetings are held on the second Thursday of every month from October until May at 7:30 pm in the Gregory Building's lecture theatre. The lectures usually last about an hour, and are followed by tea/coffee and biscuits, with a chance to chat to members of the society and to look at the publications in the society's bookshop. The meetings finish at around 9:30 pm.
 
11th October 2018
Professor Alasdair Skelton, University of Stockholm
Is mountain building a sink or source of atmospheric CO2? A case study of metamorphic fluid flow from the SW Scottish Highlands
Summary
 
8th November 2018
Professor Ian Alsop, University of Aberdeen
Unravelling soft sediment deformation in earthquake-triggered mass transport deposits
Summary
 
13th December 2018
Dr Roddy Muir, Midland Valley Exploration
Ben Nevis - remnant of a lost volcanic landscape
Summary
 
10th January 2019
Dr Jim Morrison (Retiring Presidential Address)
A broader view of the Moine Thrust
Summary
 
14th February 2019
Dr Nick Fraser, National Museum of Scotland
Joint lecture with the Glasgow Natural History Society
The Heath Robinson world of the Triassic
Summary
 
20th February 2019
Dr Tim Dempster, University of Glasgow
Clough Medal and Joint Celebrity Lecture with the Geological Society of Edinburgh, to be held in Edinburgh
Sideways views of Scottish garnets: insights into metamorphic processes
Summary
 
14th March 2019
Dr Bernard Besley, Besley Earth Science Ltd
Basin evolution in the Variscan foreland in southern Britain
 
11th April 2019
Dr Nick Schofield, University of Aberdeen
Hydrocarbon exploration in volcanic-affected basins
 
9th May 2019
Members’ Night
 
 

Lecture Summaries

11th October 2018
Professor Alasdair Skelton, University of Stockholm
Is mountain building a sink or source of atmospheric CO2? A case study of metamorphic fluid flow from the SW Scottish Highlands
 
In global carbon cycle models, mountain building is often viewed as a sink for atmospheric CO2, acting on tectonic timescales. However, recent attempts to quantify fluxes for CO2 produced by metamorphic reactions and released to the atmosphere suggest that these are an order-of-magnitude greater than CO2 uptake by chemical weathering of silicate minerals, and that metamorphic CO2 is released on millennial timescales. These hypotheses have gained support from both measurements of CO2 emissions from present-day mountain hot springs in the Himalaya and studies of metamorphic rocks from the SW Scottish Highlands. This talk will focus on findings from three decades of work in the SW Scottish Highlands.
 
Further reading: Skelton, 2013: Is orogenesis a net sink or source of atmospheric CO2Geology Today 29 (3), 102-107.
 
 
8th November 2018
Professor Ian Alsop, University of Aberdeen
Unravelling soft sediment deformation in earthquake-triggered mass transport deposits
 
Text books frequently suggest that sedimentary slump folds are “characteristically chaotic” and display “little symmetry” (Van der Pluijm & Marshak 2004) or that “folds do not propagate .... in any systematic predictable manner” (Davis & Reynolds 1996). However, is this really the case? Using examples from the Late Pleistocene (70-15 ka) Lisan Fm. exposed around the present Dead Sea, a number of fundamental questions regarding mass transport deposits (MTDs) will be addressed in this talk, including:
 
(i) What controls transport directions of basin-scale mass transport patterns?
 
(ii) What is the structural sequence of deformation during formation of MTDs?
 
(iii) Why do some fold hinges rotate and others roll during slumping?
 
(iv) Is it possible to recognise multiple events and reworking within MTDs?
 
(v) Why do some fold hinges verge back up slope?
 
(vi) Are existing models of MTDs adequate to explain the observations?
 
 
13th December 2018
Dr Roddy Muir, Midland Valley Exploration
Ben Nevis - remnant of a lost volcanic landscape
 
For three summers between 2014 and 2016, field geologists worked alongside professional climbers and botanists to undertake a new survey of the geology and Alpine flora found on the North Face of Ben Nevis, Britain’s highest mountain. The survey was co-ordinated by the Nevis Landscape Partnership, a charitable trust established in 2003 to help guide and manage opportunities for visitor enjoyment and appreciation of the wider Nevis area. Data on the geology and botany was gathered on iPhones using a digital compass clinometer FieldMove Clino, and the data was then transferred to the software application Move for further analysis and model building.
 
In 2015, geological field mapping was extended to include the whole of the late Caledonian Ben Nevis Igneous Complex (~430 Ma) and the late Precambrian Dalradian metasedimentary country rocks. The results of the new field mapping and 3D model building have provided important insights into the geometry, emplacement and preservation of the plutonic and volcanic rocks in this classic area of world renowned geology.
 
Structural data indicate that the plutonic rocks forming the Ben Nevis Igneous Complex have a laccolithic (blister like) form with a gently domed roof and was fed by magma rising up steep-sided NE-SW trending fissures in the core of the Appin Syncline. The summit region of Ben Nevis consists of late Silurian to Early Devonian age volcanic rocks originally interpreted as a thick sequence (>600m) of andesite lavas and agglomerates that were down-faulted during caldera subsidence. New field mapping has revealed that the volcanic rocks consist largely of volcaniclastic debris flows, and extensive block and ash flow deposits with minor air-fall tuff units. There is no evidence of any andesite lava flows or a volcanic vent. The volcanic detritus was derived from a volcanic centre situated to the NW of Ben Nevis, perhaps several tens of kilometres away. The rocks forming the summit region of the mountain have been re-interpreted as a large roof pendant or keel of the former late Silurian to Early Devonian volcanic land surface that once covered much of the SW Highlands of Scotland. Without the granites of the Ben Nevis Igneous Complex surrounding and protecting the volcanic rocks from recent glacial erosion, there would have been no evidence for the remnant landscape now preserved at the summit of the highest mountain in Britain.
 
 
10th January 2019
Dr Jim Morrison (Retiring Presidential Address)
A broader view of the Moine Thrust
 
The Moine Thrust (MT) marks the edge of the rocks – mainly schists of the Moine Supergroup - which were carried WNW over the Foreland of mainly Lewisian gneisses during the Scandian orogeny (440-420 Ma) when Scandia was pushed towards the eastern margin of Laurentia, probably by more than 100km.
 
There are other contemporaneous thrusts and faults to the E and W of the MT and to the E lies the Great Glen Fault (GGF) which plays a role in the overall geometry of the MT and the associated Northern Highland Terrane. Rocks now to the E of the GGF – including the modern Grampian Terrane – lay some distance to the SW at the time of thrusting.
Most interest in the MT has been in the mainland from Sleat in Skye to the N coast of Sutherland near Tongue and Faraid Head, but the MT also lies undersea to the S, where it passes to the W of Mull and eventually intersects the GGF or one of its splays. Beyond Faraid Head it continues towards Shetland, where it probably intersects the Walls Boundary Fault (northern extension of the GGF).
The talk will cover aspects of the mainland MT, and go on to consider what is known about the undersea sections.
 
 
14th February 2019
Dr Nick Fraser, National Museum of Scotland
Joint lecture with the Glasgow Natural History Society
The Heath Robinson world of the Triassic
 
The Triassic (~250-200 Mya) is a critical period in earth’s history. It saw the origin of many of the major groups of modern animals, for example mammals, crocodiles, turtles and true flies and is sometimes referred to as the Birth of the Modern World. It was also the time when the first dinosaurs walked the planet. But it was much more than this – the Triassic World was a strange mix of “conventional-looking” reptiles alongside truly bizarre Heath-Robinson contraptions. In this presentation Nick will explore the depths of the Triassic Tethys Sea, extending from the modern-day Alps and southern China, to the ancient rift basins of Pangaea, now exposed in the vicinity of Dulles airport and the Mid-Atlantic States.
 
Background reading: Fraser, N.C. and H.-D. Sues. 2011. The Beginning of the Age of Dinosaurs: a brief overview of terrestrial biotic changes during the Triassic. Earth and Environmental Transactions of the Royal Society of Edinburgh 101, 189-200.
 
 
20th February 2019
Dr Tim Dempster, University of Glasgow
Clough Medal and Joint Celebrity Lecture with the Geological Society of Edinburgh, to be held in Edinburgh
Sideways views of Scottish garnets: insights into metamorphic processes
 
Garnets are capable of recording original compositions during growth and hence allow determination of pressure-temperature paths and durations of metamorphic events. However, studies of garnet from the Scottish Highlands have questioned some key concepts of metamorphic equilibrium. Surface and internal zoning patterns reveal a failure to equilibrate at both staurolite and sillimanite isograds, and question assumptions about fluid availability and rates of intergranular transport. This emphasises the importance of kinetic controls on metamorphic reactions. Individual porphyroblasts may have a unique response to prograde metamorphism and control both subsequent reaction pathways and index mineral distribution.
 
Background reading: Dempster, T. J., La Piazza, J., Taylor, A. G., Beaudoin, N. and Chung, P. (2017) Chemical and textural equilibration of garnet during amphibolitefacies metamorphism: The influence of coupled dissolution-reprecipitation. Journal of Metamorphic Geology, 35, 1111-1130.