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SGA 9th Biennial Meeting, Dublin 2007: Report by Megan Hough

From the cobblestones of Trinity College Dublin, to the mud of Northern Ireland gold mines
Student Grant Report by Megan Hough on the 9th Biennial SGA Meeting

I would like to thank the Society for Geology Applied to Mineral Deposits (SGA) for their SGA Student Grant (via sponsorship by the Specialist Group in Economic Geology) that allowed me to attend the Ninth Biennial SGA Meeting held at Trinity College in Dublin during August 2007. My attendance to the SGA Meeting in Dublin was also funded by a Monash Postgraduate Travel Grant and an AIG-SMEDG Postgraduate Bursary.

At the “Mineral Exploration and Research: Digging Deeper” meeting, I had the opportunity to present my PhD research on the gold deposits of the Walhalla – Woods Point region in Victoria, in the “Gold Metallogenesis: Americas & Australiasia” session.

My research project is supported by ARC Linkage funding, in collaboration with Goldstar Resources NL and Geoscience Victoria. The aim of the research is to apply predictive 3D modeling to gold exploration for anomalously large deposits associated with a Devonian dyke swarm within the Walhalla-Woods Point Goldfield in eastern Victoria. This unique goldfield within Victoria allows the comparison of (i) western and eastern Victorian gold mineralization; (ii) sediment-hosted, dyke-associated and dyke-hosted gold mineralization; and (iii) structural and geochemical factors for gold mineralization.

The ten highest yielding deposits within the goldfield are either hosted within, or spatially associated with, intrusions of the Woods Point Dyke Swarm, due to the high chemical reactivity of the dolerite dykes, and the high rheological contrast between the dolerite dykes and surrounding greenschist facies meta-sedimentary units. Based on current research, consistently favourable sites for gold mineralisation in the Walhalla-Wood’s Point Goldfield are dyke-hosted quartz breccia zones. Historical production concentrated on visible gold within the shear-zone hosted laminated reef systems, although recent assay results have highlighted the increased levels of visible gold, and also the presence of disseminated gold, especially along dyke margins.

Attending the Orogenic Gold Workshop by Professor David Groves from the University of Western Australia was extremely beneficial. The short course reviewed the nature of orogenic gold provinces around the globe and deposits at different crustal levels, and then applied this understanding to gold exploration. I was particularly interested in Professor Groves’ work on the host-rock and structural controls on orogenic gold deposits, and the methods of quantifying the chemical reactivity of host rocks and rheological contrasts between the lithologies within the rock sequence.

The two day field trip to the Northern Ireland Gold Deposits was organized by Garth Earls of the Geological Survey of Northern Ireland. The group first visited Cashel Rock of the Ordovician Tyrone Igneous Complex, north of Omagh in Northern Ireland. The next day the group visited the Galantas Gold Open Cut Mine near Cavanacaw, 5 km WSW of Omagh, followed by the Tournigan Gold Project near Curraghinalt, 15 km NE of Omagh. The Cavanacaw and Curraghinalt orogenic gold deposits are hosted within an inlier of Neoproterozoic Dalradian metasediments. The gold mineralization is associated with the later stages of the Caledonian Orogeny (~470 – 400 Ma), and is structurally controlled by the N-S Omagh lineament and the NE-SW trending Omagh Thrust (an extension of the Caledonian Highland Boundary Fault in Scotland).

Cashel Rock of the Ordovician Tyrone Igneous Complex is a brecciated rhyolite surrounded by tuff, and hosts volcanogenic massive sulfide mineralization. It is part of an ophiolite complex which obducted due to the closing of the Iapetus Ocean during the Caledonian Orogeny. The Neoproterozoic inlier of Dalradian meta-sediments which host the gold mineralization, was thrust over the Ordovician Tyrone Igneous Complex.

The Curraghinalt gold deposit is a high-grade mesothermal quartz-sulphide gold vein system, with visible gold and negligible arsenopyrite. The gold mineralization formed close to the surface, and is highly oxidized, is copper-rich and the wallrock alteration extends no more than 0.5 metres from the veins. The lower temperature Cavanacaw gold deposit is characterized by gold-bearing sulphides and clay gouge associated with steeply east-dipping quartz veins. The largest and most continuous mineralized structure is the Kearney Structure. Most gold is associated with pyrite, arsenopyrite and galena, with little to no visible free gold.

The opportunity to attend the Ninth Biennial SGA Meeting, and associated short course and field trip, allowed me to meet and learn from world-renowned gold researchers, and to visit differing styles of orogenic gold deposits. I have learnt more on the structural and host rock controls on gold mineralization, which I can now apply directly to my research. On the fieldtrips, I was also able to view drillcore from both deposits and to access two mines - many photos were taken of the geology and mineralization for comparison with my field area!


Group photo at the Galantas Open-Cut Gold Mine near Cavanacaw. Megan Hough stands centre back.

SGA 9th Biennial Meeting, Dublin 2007: Report by Leon Bagas

Where am I? A student’s view of the 9th Biennial SGA Meeting in Dublin
By Leon Bagas (Centre for Exploration Targeting, University of Western Australia) 1

1 Leon was supported by a travel grant from the Specialist Group in Economic Geology, via student sponsorship of the SGA

Waking from adventures in the tropical jungles in memories of the distance past, I thought I was home in bed on a Sunday morning anticipating Macca on the radio in 'Australia all over'; some would say that this must have been a nightmare. Opening my eyes to the first light of the morning, I was disorientated by the unexpected sight of the inside of my swag and thinking, "Where am I?". Reality quickly returned me to the Tanami Desert, which is a strange place in northern Australia, where many hidden treasures are waiting to be discovered.

A moment later, a yet deeper reality dawned on me when I remembered I had a presentation to prepare for my first international conference on the other side of the world at Dublin in a place called Eireann (Ireland). This is the place where summer was more like winter in Perth of Western Australia, yet the locals walked the streets in summer clothing while I wore my wind-proof jumper.

This was the presentation that mysteriously morphed from a beautifully designed poster into an oral presentation; a true mystery that escapes explanation. I felt like a bunny that had my workload increased while in the desert; oops, bunnies are unwelcome visitors to Australia and the politically correct term there is the endangered marsupial called bilby (members of the Peramelemorphia biological order and the largest of the bandicoots) that vaguely looks like a bunny; yes I am the 'bilby'.

As the days approached for my journey to one of Australia's European ancestral lands, the level of anxiety exponentially increased. Having a Pure Mathematics Degree, as well as a Master's Degree in Economic Geology, I can use mathematical terminology like 'exponentially' and, what is more, understand them. Many times I have wondered why I ever took an interest in the sciences of improbability known as Abstract Algebra and Geology and have consistently concluded. "Because I can". Yet in my lifelong pursuit of science like a rare treasure (even as a 'mature-aged' student that doesn't understand what it means to act my age), I cannot overcome the anxiety that builds up with the seemingly never-ending reproducing butterflies that infest my stomach before delivering a paper (any paper) in front of an audience (any audience).

On a Monday morning, in Eireann during the beginning of August in the year 2007 of our Lord, in the land of the O'Calliaghs, whom Ned Kelly made famous in the state of Victoria in Australia, I was numb. This form of stoicism started with a sleepless night and built up to a crescendo when introduced to the audience by my PhD supervisor Frank Bierlein. We have a mutual respect for each other and we take each other's requests seriously by completing our tasks well before time (sometimes even before asked).

Months earlier, Frank told me that my second paper, to be delivered during the 9th Biennial Conference, would be an oral presentation because of its importance. The topic was on mineral deposits in Proterozoic rocks of Australia, and the exiting part was that it was to delivered in front of hundreds of geoscientists from throughout the world. Furthermore, the talk was not to be one hour, not 30 minutes, not 20 minutes, but a quick 15 minutes. Yes, 15 minutes, and the co-author, who suggested I should give it orally while he was having fun in Russia, promised to help me by giving me prepared slides. Exactly five minutes after seeing what he prepared, it became obvious that I had to start from scratch. So, every night for many weeks in the Tanami Desert I was busy for an hour rewriting the presentation (including the drafting of figures).

Back on the day that Frank introduced me to the audience in Eireann, I stepped up to the podium, took three deep breaths, and thanked him for the introduction. This was a strange moment mid-between when everything was in an excruciating pain of anxiety to what felt like seconds from the time I started until the time Frank held up a sign saying I had run out of time. This was the impossible task I was volunteered to try in a 15 minute talk.

Afterwards, Frank told the audience that the presentation was based on a 60 page 'door-stopper' paper in a special volume of Precambrian Research soon to be published. Returning to my seat in relief I noticed someone sitting in front of me who looked far more anxious than I was moments before. It dawned to me that she was suffering from the same infestation of stomach butterflies. Leaning forward, I touched her shoulder saying, "Relax, you will do fine". Turning towards me, she smiled with appreciation.

Concluding another adventure (or trial) in my life, I had four days on a downhill journey to my next paper that I was to deliver. It is so hard to be introverted, but someone has to do it.

Later that same day, Dr Pietro Guj, the former Director of the Geological Survey of Western Australia, whom I once regarded as unapproachable, approached me saying that I succeeded in completing the impossible task (putting forward my points and that the slides were superb). Soon afterwards, a lecturer from a university in the USA requested a copy of the paper. I felt honoured and grateful.

Thus ended my first day of a conference in the land of the O'Calliaghs and the book of Kells, which was written in the ancient land of Eireann. This is a place of beautiful and hospitable people with a welcoming smile who are happy to be friendly.

This is also a token of my thanks to people like Sabine Lange, Colin Andrew, Anna Vymazalova and many others who, through sponsorship by SGA, made it easier for me to visit a beautiful edge of Europe. To all these people, I give gratitude with the hope that I can give, as they did, and not just take. With this in mind, I have resolved to be a life-long member of SGA so that this will help students of the future to attend SGA biennial conferences.

 

SGEG-GSAWA Komatiite Debate, University of Western Australia, Perth 2007: Report by Marco Fiorentini

The Mini-Symposium – A New Forum for Discussion of Hot, Controversial Topics
By Marco Fiorentini, Non-Executive Member, SGEG Committee

Over 50 people attended the recent hot-topic-debate “Do you prefer your komatiites wet or dry?” that took place at the University of Western Australia on May 01, 2007. In this debate Dr Steve Barnes (advocate of the dry hypothesis) and Marco Fiorentini (advocate of the wet hypothesis) discussed the role of volatiles in ultramafic melts and offered their opinions and thoughts on this highly controversial topic.

The format for this new discussion forum was put forward by SGEG. The purpose of the mini-symposium was to bring together in an informal environment geoscientists with contrasting viewpoints on controversial topics and have them discuss the scientific evidence that backs their thinking. Even though we did not resolve the controversy, the komatiite debate was very beneficial and informative for all attendees and stimulated ample discussion about the role of volatiles in the genesis of Ni-Cu-(PGE) deposits.

The drinks and nibbles that were offered after the session enticed many people to stay on and continue the discussion. The komatiite debate was so successful that SGEG will organise a second mini-symposium on another controversial topic in the near future.

 

 

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