Lecture Synopsis:
Gases in rocks may be present as vapour bubbles in fluid inclusions, gas molecules adsorbed onto mineral surfaces, or accumulated within fractures, voids and pore spaces. Gases may also be produced by a number of mechanisms – biogenically (i.e., microbial processes) or abiogenically (e.g., by mineral alteration and reaction). Many mines in South Africa are prone to gas outbursts and the number of flammable gas reports and accidents are steadily rising. For example, methane is recognized as a hazard in gold and platinum mines as well as coal mines. Gases and volatiles present in some lithologies are sensitive to physical changes of the host rock, such as excavation that causes depressurisation of the surrounding rock mass. This can cause a release of gas and is an important consequence of any mining or underground construction activity. In cases of outburst, the release of gas may be very sudden and the sources and pathways of gases must be understood in order to facilitate and implement appropriate health and safety criteria and mine operation regulations.

In this talk, we will look at a case study of a underground platinum mine in South Africa suffering numerous gas outbursts and see how applied mineralogy, petrology, fluid inclusion studies and novel in situ gas analyses together with time-lapse mapping can be used to identify the causes and mechanisms of gas outbursts. Equipped with this knowledge, we hope to be able to forecast the risk of outbursts in the future and thereby help to safeguard miners from injury as well as saving the mine the financial burden caused by these events.

Speaker Bio:
Hannah is an economic geologist and geochemist at the Camborne School of Mines, University of Exeter. Her research interests include the metal budget of the mantle, the underlying controls (in space and time) for mineralisation in the crust, the 'fingerprints' of metallic mineralisation and the ancient histories of the oldest portions of the Earth's lithosphere (cratons).

Hannah has further research pursuits in the generation and mitigation of gases in igneous rocks, particularly hazardous in some underground mines, and it is this that she talks about in this lecture.

Schedule:
18.00 - Start of Livestream
18.00 - Welcome and Start of Lecture
18.50 - Question and Answer session
19.30 - End of stream

Note on Q&A session:
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