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:

March 2023 Monthly Talk

Speaker: Dr. Graham Banks,  Senior Principal Geologist, WSP Mining Canada

Title: Mapping Mineral Systems Under Sediment Cover: The Right Geophysics and Structural Geology at the Right Scale at the Right Time

Date: Wednesday, March 29, 2023

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

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

Abstract:

This presentation is an expanded version of a seminar given at PDAC 2023 in the session called
Geophysics: Exploration Case Histories:

https://www.pdac.ca/convention/programming/technical-program/sessions/technical-program/geophysics-exploration-case-histories

The objectives of geophysics and structural geology in mineral exploration should be to: (a) formulate exploration hypotheses to then, (b) test the existence of a mineral system, its plays and its deposits under sediment cover by, (c) sequentially narrowing the team’s uncertainty range through province, then play, then prospect, then borehole scales. To make undercover mineral exploration more efficient, the optimal combination of survey types that test objectives a to c should be applied, instead of conducting the most familiar suite of surveys.

The accompanying presentation will summarize how geophysics integrated with structural geology was used by Southern Geoscience Consultants in 2021, to assist Battery Minerals Limited focus its exploration program towards understanding the under cover geology. The project area is in the Stavely-Stawell metallogenic province of gold and base metals in Australia. The interpretation team did a gap analysis and a SWOT analysis of the existing data, built a district-scale geological framework, made a litho-structural interpretation, to then identify areas of further interest for deposit-scale targeting.

Thank you to Battery Minerals Limited and Southern Geoscience Consultants for permission to display this case study.

Bio:

• A senior principal geoscientist with 17 years in industry (copper, lithium, rare earth elements, nickel, gold, petroleum) spanning tectonic to drill core scales.
• Evolved from a structural geologist to advisor of exploration-mining organisations: how to translate a project’s geoscience into probability of success, uncertainty, risk and value.
• Helps clients create success-case and failure-case hypotheses before spending money and effort collecting costly data.
• Integrates structural geology with geophysics: 10 years interpreting reflection 2D and 3D seismic; Interpret borehole image log data; Structural geology maps from aeromagnetic and spaceborne imagery.
• A regional-scale geologist, with years of experience building district-scale geology models.
• Integrates structural geology with mineral deposit-forming processes in sedimentary, igneous, metamorphic regions.
• Creates professional development workshops for exploration-mining companies, geological surveys, policy-makers, universities and governments: exploration risk and value.
• An external advisor on the European Union’s lithium exploration program.
• Senior Principal Geologist, WSP Mining, Canada.
• Director of Route To Reserves Consulting Inc.
• Associate of Southern Geoscience Consultants.
• Ph.D. Structural and igneous geology of VHMS deposits. Cardiff University, U.K.
• BSc. Geology. 1st class with Honours. University of St. Andrews, U.K.

https://www.linkedin.com/in/graham-banks-aba5bb26/

https://www.researchgate.net/profile/Graham_Banks3

https://www.wsp.com/en-ca/sectors/mining

https://sgc.com.au/

https://www.batteryminerals.com/

https://www.route2reserves.com/

Webinar

A recording of this talk is available on our Youtube channel.

BCGS is pleased to support an initiative that provides guidelines for geophysical uses of drone technology. Drone Geoscience LLC has generously prepared a website with guidelines for using drones for geophysics.

See also our “Drones” page, under the “Resources” menu, or review materials from the BCGS drone workshop from May 2022.

Thanks are extended to Ronald S. Bell, Senior geoDRONEologist & Geophysicist with Drone Geoscience LLC.