We would like to bring to your attention the following upcoming events within the community that may be of interest to you and your colleagues. Additional details are below.

• UBC will be hosting the 7th International Symposium on Three-Dimensional Electromagnetics (3DEM-7) from Nov 13 to 17th. DETAILS BELOW
• MDRU & DMEC are organizing a one day short course titled “EM for Geologists” to be held on Nov 17. DETAILS BELOW
• BCGS Monthly talk – next item.

November 23, 2023 – Monthly Talk

Speaker: Jorge Lopez-Alvis, University of British Columbia

Title: Using convolutional neural networks to classify UXO with multi-component electromagnetic induction data

Date: Thurs, Nov 23, 2023

Time: 4:30pm to 5:30pm PDT

Location: In-person: Room 111 – 409 Granville Street, Vancouver, BC, V6C 1T2

Virtual: via Zoom, to be announced.

Note: This will be an in-person meeting

Abstract

Electromagnetic induction (EMI) methods are commonly used to classify unexploded ordnance (UXO) in both terrestrial and marine settings. Modern time-domain systems used for classification are multicomponent which means they acquire many transmitter-receiver pairs at multiple time-channels. Traditionally, classification is done using a physics-based inversion approach where polarizability curves are estimated from the EMI data. We developed a convolutional neural network (CNN) that classifies UXO directly from EMI data. The architecture of our CNN produces high-resolution results and can handle the multiple transmitter-receiver pairs and the per-line acquisition of multicomponent systems. The CNN is trained using synthetic data generated with a dipole forward model considering all possible UXO and clutter objects. In this presentation, we will discuss how we structure the data to be input into a neural network, how we design the network, and how training is performed. Our approach was tested on data acquired with the UltraTEMA system in the Sequim Bay marine test site. For this test dataset, our CNN-based approach detects all UXOs and classifies more than 90% as the correct type while also discriminating ~70% of the clutter. An overview of our workflow applied to this dataset and some discussion of the classification results will be presented.

Bio:

Jorge is a Postdoctoral Fellow from the Geophysical Inversion Facility (GIF) group at UBC. He has a background in near-surface geophysics and using machine learning in geophysics. His current research involves developing an approach for using neural networks to classify UXO directly from electromagnetic data. He completed a joint PhD program at Ghent University and University of Liège where he explored the use of deep generative models (or generative A.I.) to produce geologically realistic images from geophysical data.

3DEM-7 Symposium: Nov 13-17, 2023,   https://3dem-7.geosci.xyz/

The 7th International Symposium on Three-Dimensional Electromagnetic (3DEM-7) will be held on Nov 13-15, 2023 and we are looking forward to welcoming the EM community to Vancouver!

Registration is open at https://3dem-7.geosci.xyz/#registration and the abstract submission deadline has been extended to Oct 20: https://3dem-7.geosci.xyz/#abstracts-call. If you plan to attend, we appreciate early registration so that we can orchestrate the catering.

We are still seeking sponsors, so if your organization is interested in sponsoring 3DEM-7, please reach out to Lindsey Heagy (lheagy@eoas.ubc.ca) and Eldad Haber (ehaber@eoas.ubc.ca).

If you are in Vancouver and are willing to billet students / postdocs for the event, please contact Lindsey (lheagy@eoas.ubc.ca). There are some folks with limited travel funds who would like to attend, but require additional support.

Workshop: EM for Geologists (MDRU/DMEC): Nov 17, 2023

A one day short course covering electromagnetic methods, case studies, etc. See below link for the schedule and to register.

https://www.mdru.ubc.ca/training/sc125-em-for-geologists-workshop/

STUDENTS NOTE: Condor Consulting will cover the registration fee ($60) for any student who wants to attend. DMEC will cover $200 for any out-of-town student who attends to defray expenses (receipts required).

Speaker: Brendan Howe, Teck Resources Limited

Title: An Empirical Geophysical Model for Porphyry Copper Deposits in the Laramide Copper Province

Date: Thurs, August 24, 2023

Time: 4:30pm to 5:30pm PDT

Location: Room 111 – 409 Granville Street, Vancouver, BC, V6C 1T2

Abstract:

The Laramide copper province is located in southwestern North America, covering parts of Arizona, New Mexico, and Texas in the U.S, in addition to Sonora, Chihuahua, Sinaloa and Baja California in Mexico. Porphyry copper mineralization is associated with Laramide age (~80-45 Ma) magmatism and has been estimated to represent ~300 million tonnes of copper metal, making it a globally significant accumulation of the red metal. The geological and geochemical manifestation of these mineralizing systems have been well documented. Specifically, exploration models based on alteration zonation and trace element geochemistry have been developed and successfully deployed in the province since the late 1960’s. As a result of post Laramide extension and deposition, much of the province is covered by post-mineral rocks or sediments, and it can be argued that the greatest residual potential for future discoveries is located within the covered regions. Consequently, geophysical datasets are playing a more prominent role in integrated targeting of porphyry systems. In this extended abstract, we present a series of observations and interpretations of geophysical data from various deposits in the province with the goal of developing an empirical model to guide selection of geophysical method, interpret subsequent results and ultimately contribute to future exploration success.

Bio:

Brendan Howe is the Technical Manager of Exploration at Teck Resources. Prior to joining Teck he worked for Barrick Gold as a Senior Geophysicist. He completed a combined BSc. / B.Comm in Geology-Finance from the Australian National University. Brendan is a past chair of the BC Geophysical Society.

Webinar:

Speaker: Peter Fullagar, Fullagar Geophysics Pty Ltd.

Title: Beyond Plates – fast TEM inversion using conductive ellipsoides

Date: Thursday, May 25, 2023

Time: 4:30pm to 5:30pm PDT

Location: Room 111 – 409 Granville Street, Vancouver, BC, V6C 1T2

Abstract:

Interpreting TEM anomalies in terms of conductive rectangular plates is effective in many situations. However, not all conductors are thin and planar. Triaxial ellipsoid conductors represent an attractive alternative: geometrically simple (corner-free), mathematically tractable at early and late time limits, and able to encompass shapes ranging from poddy to tabular to lensoidal to elongate. Accordingly a fast  magnetostatics-based algorithm has been developed to compute ellipsoidal conductor responses in both resistive and inductive limits. Focusing on TEM data close to the resistive or inductive limit is attractive not only because it simplifies both the physics and the computations, but also because in many cases the late time or early time response is of particular interest in mineral exploration. Inversion of measured data entails adjustment of selected ellipsoid parameters, subject to user-imposed upper and lower bounds. The methodology is suitable for downhole, ground, or airborne TEM, either impulse or step response. In this presentation the conductive ellipsoid forward and inverse algorithms are briefly described and illustrated via application to TEM field data.

Bio:

Peter Fullagar holds a PhD in geophysics from UBC. He has over 40 years experience in base metal and precious metal exploration, and in metalliferous and coal mining geophysics. He worked for a total of 14 years with Western Mining Corporation (WMC) and Rio Tinto in Australia. Peter has also held academic and research positions, at Ecole Polytechnique in Montreal and with CSIRO Exploration & Mining in Brisbane. Since his tenure as Chief Geophysicist for WMC in the early 1990s he has promoted utilisation of geophysics in operating mines. He established Fullagar Geophysics Pty Ltd in Brisbane in 1998 and has consulted privately for the past 25 years. During that time he has developed geophysical modeling and inversion software, mostly for EM, potential fields and borehole logging, with a focus on integrated interpretation of geophysics and geology. He has also supervised several MSc and PhD students, and has taught undergraduate courses in potential fields, and electrical and EM methods, at the University of Queensland. He is currently based in Noosa, Queensland.

Webinar:

Speaker: Heather Schijns, Global Principal Geophysicist, Seismic Geophysics, BHP

Title: 3D Seismic Feasibility Study of Olympic Dam

Date: Wed, May 10, 2023

Time: 4:30pm to 5:30pm PDT

Location: Room 111 – 409 Granville Street, Vancouver, BC, V6C 1T2

Abstract:

Olympic Dam is a world-class IOCG (iron-oxide copper gold) deposit located in Southern Australia, and is the flagship deposit for the IOCG deposit-style. It is one of the largest known copper deposits and single largest uranium deposit in the world. Mineralisation at Olympic Dam is disseminated in nature, and is hosted in hydrothermal breccia within Roxby Downs Granite. Between the gradational nature of the contacts between the iron-oxide rich breccia and the altered granite, and the small-scale heterogeneity of the breccia itself, few apparent opportunities exist to generate coherent seismic reflectivity. The feasibility of hard rock reflection seismic to effectively image IOCGs, and more broadly, deposits with disseminated mineralisation, has been unclear to date, with few examples in the literature. In 2021, BHP undertook an in depth 3D seismic feasibility study of Olympic Dam. Utilising a physical property model that included representative 3D geometry and geological variability, the feasibility study allowed detailed examination of the impact of various seismic acquisition and processing decisions on successfully imaging this complex geology. Here we present the feasibility study process and results.

Bio:

Heather Schijns joined BHP in 2017 and works out of Vancouver, Canada as Global Principal Geoscientist, Seismic Geophysics.  In this role Heather provides technical guidance and strategy for application of seismic methods and R&D across global copper, nickel, coal, iron ore and potash assets for purposes ranging from resource exploration/targeting to geotechnical characterisation. 
Prior to joining BHP, Heather worked in exploration-focused roles at companies including MMG, Aurora Geosciences and TerraNotes using a broad range of geophysical methods. Work took her across 5 continents and offshore, including major projects in arctic Canada, Brazil and Tanzania.  Heather is a graduate of the University of Alberta, where she completed an MSc and a PhD in geophysics with a focus on seismic rock physics of metamorphic rocks. 

Speaker: Ken Witherly, President, Condor Consulting Inc.

Title: What Lies Beneath? A Reflection on the Porphyry Copper Exploration Model

Date: Thursday, April 20, 2023

Time: 4:30pm to 5:30pm PDT

Location: Room 111 – 409 Granville Street, Vancouver, BC, V6C 1T2

Abstract:

Electrical methods have been applied to the search for porphyry copper and IOCG deposits since the early 1950s. While there  is a generally accepted model of disseminated sulfides giving rise to a chargeability response, no clear association has been attached to what EM surveys may be responding to. Work in the early 1990s (Nickson 1993) showed the well-developed supergene blankets over a porphyry copper could be conductive; this observation was however, never applied formally to generally accepted porphyry targeting models. The presence of other conductive zones associated with porphyry copper deposits is even less well studied. On the geological side, while there is a vast body of literature describing porphyry copper deposits and how to discover them, in very few cases do these studies even speculate if anomalous concentrations of sulfides could be conductive. On the geophysical side, observations of unexpected conductivity associated with porphyry systems is sometimes noted but these observations typically stop short of suggesting that there could be a more general observation made that a new class of geophysical feature should be defined. The present study is felt to have gathered a sufficient number of case studies which show that a significant number of porphyry copper deposits posse a mineralogical character which can be identified with EM techniques. This thesis can have significant implications as to how porphyry copper are explored for, especially those at depths >500 m, a generally accepted cut-off for IP techniques.

This presentation is based on a similar talk given in AEGC 2019 in Australia. The talk has been updated several times since. The abstract from the 2019 talk can be downloaded below and forms a good summary.

http://www.bcgsonline.org/download/2099/?tmstv=1681224608

Bio:

Ken Witherly graduated from UBC (Vancouver Canada) with a BSc in geophysics and physics in 1971. He then spent 27 years with the Utah/BHP Minerals company during which time as Chief Geophysicist, he championed BHP’s programs in airborne geophysics which resulted in the development of the MegaTEM and Falcon technologies. In 1999, Ken helped form a technology-focused service company that specializes in the application of innovative processing and data analysis to help drive the discovery of new mineral deposits. In 2017, he helped establish the Women Geoscientists of Canada, a group dedicated to support early career women in the minerals industry.

Webinar: