The BC Geophysical Society will be hosting Dr. James Macnae, the inaugural Len and Genice Collett Distinguished Visiting Lecturer in Geophysics, who will be presenting a half-day short course titled:

“Integrated interpretation of airborne electromagnetic surveys: Determination and use of appropriate geophysical models”

Dr. James Macnae, RMIT University, Melbourne, Australia.

This half-day (AM) course will cover:

1)      The basics of geophysical electromagnetics (EM), time and frequency domain
2)      Airborne EM systems, trade-offs and recent advances
3)      The physical limits of conductivity resolution with AEM
4)      Detectable geology: Earth conductivity variations
5)      Consideration of computed geophysical models, direct and inverse

• Stitched 1D for quasi-layered environments
• 2D and 2&1/2D
• 3D, parametric and voxellated

6)      Case histories: Using computed AEM models to guide geological interpretation: Successes, limitations and failures
7)      Where might AEM be in 10 years?

REGISTRATION IS OPEN
(Deadline 5:00pm, Tuesday, March 26, 2019)

Payment will be accepted through PayPal. Click on the “Pay Now” button below.

To register as a student, please email us at info@bcgsonline.com.

BCGS Technical Talk – February 20, 2019

This month we have two exciting speakers.

1. Sarah Devriese, Condor North Consulting
2. Shawn Letts, Anglo American plc

Date/Time: Wednesday, February 20, 2019 @ 4:30pm PST

Location: 4th Floor Conference Room, Room 451, 409 Granville St. (UK Building at Granville and Hastings), Vancouver

Title & Abstracts:

Sensitivity-based data reduction of large 3D DC/IP Surveys
Sarah G. R. Devriese*, Robert Ellis, Ken E. Witherly, Condor North Consulting ULC, Geosoft

Survey companies are increasingly favouring large 3D DC resistivity (DC) and induced polarization (IP) surveys to aid in exploration programs. We present a sensitivity-based data winnowing algorithm that can reduce the amount of data from 3D DC/IP surveys to decrease the inversion computation time but retain similar levels of resolution in the final model. The method is based on the sensitivity of the data to the model space and designed to retain equal sensitivity coverage throughout the model space. The algorithm is tested on both synthetic and field examples.

Interpretation and Benefits of Full-Tensor Squid-Magnetometer Data
 Shawn Letts^1* Joel Jansen¹, Louis Polomé³, Anre Vorster^2
1Anglo American plc
²De Beers Group of Companies
³Spectrem Air Pty Ltd

Anglo American and De Beers have been supporting the development of low-temperature Super-conducting Quantum Interference Device (SQUID) magnetometers for over 15 years, with most of the research undertaken by the Leibniz Institute of Photonic Technology (IPHT) in Jena, Germany.  This partnership lead to the development of a TEM sensor able to measure precisely the late-time step-response of the earth.  The principal advantages of SQUID sensors for TEM surveys are: direct measurement of the magnetic field (hence the step-response of a transmitted square-wave), high magnetic field resolution at low frequencies, and a flat frequency response from DC to 10kHz.

Early research also focussed on passive magnetic-field measurements, including the development of a Full-Tensor Magnetic Gradiometer (FTMG).  Advantages of measuring the full tensor over the total-field include:  higher spatial resolution; a five-fold increase in information about the earth’s magnetic field, including information about magnetic remanence; and insensitivity to diurnal effects.

Standard cryogenic Dewars (cryostats) are vertical cylinders for ease of use, but this shape is not optimal for airborne surveys owing to the high-drag of the vessel.  To overcome this drawback, De Beers and Anglo American funded IPHT to develop and construct a horizontal-cylinder cryostat that easily and aerodynamically fits into a fixed-wing pod or a conventional rotary-wing towed bird.  The new system was trialed by De Beers over four projects during 2018, totaling ~ 17,000 line-km.
The results of these surveys corroborate the advantages predicted by forward modelling, being increased spatial resolution and a much-improved interpretational capability of the causative geology.  The accompanying presents survey results from a highly complex terrain in southern Africa to illustrate the aforementioned advantages of FTMG.

Interpretation of gravity and magnetic data: from geophysics to geology
A short course offered in collaboration with the BCGS

Presented by: Dr. Yaoguo Li
Centre for Gravity, Electrical, and Magnetic Studies,
Department of Geophysics, Colorado School of Mines

A 1-day short course presenting the state of art and practice in 3D inversion-based quantitative interpretation of gravity and magnetic data. With a focus on mineral exploration the course will present the basic concepts of 3D inversion and discuss the interpretation of gravity, gravity gradient, and magnetic data to extract geologic information,

Course Flyer: Poster_Yaoguo_ShortCourse_v2.pdf

A recent article in The Leading Edge by Dr. Yaoguo Li discusses the importance of quantitative geophysical interpretation in mineral exploration indicated by the below quote.
(Li, et al., The Leading Edge, January 2019, Vol. 38. No. 1: pp. 60-66.)

Article: YaoguoLi_2019_TLE.pdf

Furthermore, what is required is a mindset that may be described by the following adage: “No one cares about geophysics unless it can solve geology problems.” Thus, the focus should be on geology and not necessarily on geophysics by itself. Adopting this mindset logically requires geophysicists in research and practice to think and act as geoscientists with some understanding of the geologic and mineral systems in which we explore, of mineralogy, and of geochemistry. Consequently, we cannot focus primarily on geophysical methods in a semivacuum setting.”

REGISTRATION NOW AVAILABLE
(Deadline 12:00pm, Wednesday, Jan 23, 2019)

Payment will be accepted through PayPal. Click on the “Pay Now” button below.

Course Outline:

Gravity and magnetic data are among the most widely available geophysical data in mineral exploration and arguably have the most extensive areal coverage among all geophysical data with large depths of investigation. 3D inversion techniques have emerged as a major tool kit in the quantitative interpretation of these data over the last two decades. The ability to reconstruct the distribution of density or magnetic properties in various geological units through inversions has shifted interpretations from the data domain to the model domain and, thereby, transformed the interpretation from bump hunting in data displays to imaging structure and composition in 3D representations of the subsurface. More recently, the integration of inversion techniques is also poised to make major contributions to the emerging field of geology differentiation, which seeks to differentiate and characterize different lithology units, mineralized zones, or alteration zones by constructing quasi-geology models.

This course presents the state of art and practice in 3D inversion-based quantitative interpretation of gravity and magnetic data. The course will review the data acquired for mineral exploration with focus on newer data types, present the basic concepts of 3D inversion and the use of inverted models in the interpretation of gravity, gravity gradient, and magnetic data to extract geologic information, and demonstrate the power of integrated interpretation through joint inversion with petrophysical constraints and geology differentiation. The six topic areas covered in the course are as follows:

– Basic Theory: magnetic, gravity, and gravity gradiometry data in mineral exploration
– 3D Inversion: A means to image subsurface geology
– Gravity and Gravity Gradiometry: data processing and case studies
– Remanent Magnetization Inversion: new information about geology
– Joint Inversions: connecting to geology through property data
– Geology Differentiation: moving geophysics to geology interpretation

Dr. Yaoguo Li is a Professor in the Department of Geophysics at the Colorado School of Mines, and Director of the center for Gravity, Electrical and Magnetic Studies (CGEM). He currently leads the Gravity and Magnetics Research Consortium (GMRC) sponsored by the petroleum and mining industry. He is specialized in geophysical inversion methods for potential-field, DC/IP, and electromagnetic data and in geology differentiation with a focus on applications in mineral and petroleum exploration and production. He is an Associate Editor for the journal GEOPHYSICS. He is a member of AGU, EAGE, and SEG.

KEGS/BCGS Roundup Breakfast – Tuesday, January 29, 2019

Speaker: Dr. Glyn Williams-Jones, Centre for Natural Hazards Research, Department of Earth Sciences, Simon Fraser University

Title: Mt. Meager volcano – a complex and active multi-hazard system

Date/Time: 2019-01-29 @ 7:30am – 9:00am

Location: Princess Louisa Room, The Fairmont Waterfront Hotel
900 Canada Place, Vancouver, BC V6C 3L5

Registration: Online at www.kegsonline.org (Deadline Jan 27, 2019)

Abstract:

Climate change is causing the retreat of glaciers throughout the Canadian Cordillera, including at volcanoes. Glacial retreat can lead to unloading at the base of steep slopes, which coupled with the often wide spread hydrothermal alteration of volcanic massifs, can facilitate large landslides capable of traveling tens of kilometres and impacting population centres and infrastructure. Increasing summer temperatures can further heighten snowmelt that is capable of infiltrating slopes and triggering landslides.

The Mount Meager Volcanic Complex (MMVC), a large volcanic system located 65 km northwest of Pemberton, BC, is the site of long-lived volcanic activity. Mt. Meager was the site of Canada’s largest recent explosive event, ~ 2430 years ago, with the eruption of 0.8 km³ of material sending ash 530 km east to Calgary. It currently hosts actively degassing fumaroles that have formed melt caves in the Job Glacier on the northern flank of massif. The long-lived activity of Mt. Meager has also made it the target of extensive geothermal energy exploration and important nearby infrastructure exists in the form a run-of-river hydroelectric project on the upper Lillooet river.

Importantly, Mt. Meager is the also site of Canada’s largest historic landslide in 2010 with a total failure volume of 53 ± 4 x 10⁶ m³. Field mapping and terrain analysis suggests that it was likely weakened due to substantial changes in the hydrological system associated with loss of glacier ice (~1.3 km³ of ice loss since 1987). Continued InSAR monitoring has identified numerous hydrothermally altered slopes (27 at >5 x 10⁵ m²) that are actively deforming; some of these slopes are moving at up to 36 ± 10 mm per month during the summer and have volumes > 300-500 x 10⁶ m³. As such, there is a significant and imminent threat to infrastructure and communities downstream.

This talk will present an overview of the volcanic history, ongoing and future research projects as well as the current status, geohazards and new monitoring initiatives on the Mt. Meager Volcanic Complex.

About the Author:

Dr. Glyn Williams-Jones,

B.Sc. U. Montréal, 1994; M.Sc. U. Montréal, 1997; Ph.D. Open University (UK), 2001; Postdoc U. Hawaii Manoa, 2003.

Glyn is a Professor in the Department of Earth Sciences at Simon Fraser University and co-Director of the Centre for Natural Hazards Research. The Centre for Natural Hazards Research has a broad mandate to conduct innovative training and research on geophysical processes that are a threat to the population and economic infrastructure of Canada.

Glyn is a physical volcanologist whose multidisciplinary research involves geochemical and geophysical modelling in conjunction with terrestrial and satellite remote sensing to investigate the processes responsible for triggering volcanic eruptions as well those controlling persistently active volcanism. The principal focus of his research is the investigation through active monitoring and retrospective studies of the interaction between the intruding magma and that already residing in the reservoir. The goal of this work is to gain insight into the precursory signals of volcanic activity and the mechanisms that trigger volcanic eruptions.

Gravity and Magnetic Methods for Mineral Exploration, Dr. Yaoguo Li.

Presented by EAGE and hosted by the BC Geophysical Society.

This 1-day workshop covers the concepts and methodologies of gravity, gravity gradiometry, and magnetic surveys. This course will focus on the methodology, numerical computation, solution strategy, and applications of 3D physical property inversions of gravity and magnetic data sets.

Course Flyer: EAGE Short Course Flyer

PRE-REGISTRATION NOW AVAILABLE
Email info@bcgsonline.org
to secure your spot for only CAD 115
Only ten early-bird spots available!

Click on the link for the EAGE course page. EET11 – Gravity and Magnetic Methods

Course Outline
Part-I: Common concepts and methodologies
Fundamentals of potential-field data observed in gravity, gravity gradiometry, and magnetic surveys
Data processing methods based on equivalent source technique and inverse formulation
3D gravity and magnetic inversions and the practical strategies for their efficient solution and applications to large-scale problems
Binary inversion potential-field data in 3D
Gravity gradiometry

Part-II: Mineral exploration
Inversion and interpretation of magnetic data affected by remanent magnetization
Case histories from mineral exploration

Participants’ profile
We anticipate the geoscientists in the following areas will benefit from the course:
Potential-field methods
Mineral exploration
Integrate interpretation
Reservoir monitoring
Groundwater hydrology

Prerequisites
Participants are expected to have basic background in applied geophysics and some knowledge of potential-field methods.

Yaoguo Li received his B.Sc. in geophysics from the Wuhan College of Geology (currently China University of Geosciences) in 1983, and a Ph.D. in geophysics from the University of British Columbia in 1992. He worked with the UBC-Geophysical Inversion Facility at UBC from 1992 to 1999, first as a Post-doctoral Fellow and then as a Research Associate. He is currently an Associate Professor of Geophysics at the Colorado School of Mines and leads the Center for Gravity, Electrical, and Magnetic Studies (CGEM) and the Gravity and Magnetics Research Consortium (GMRC). He is a co-recipient of the 1999 Gerald W. Hohmann Award, SERDP 2007 Project of the Year Award, and 2010 ASEG-PESA Laric Hawkins Award. His research interests include inverse theory; inversion of gravity, magnetic, and electrical & EM data arising from applied geophysics; and their application to resource exploration, environmental, and geotechnical problems. He has been doing research in these areas and has developed or co-developed a number of program libraries for inverting different types of geophysical data. These include DCIP2D, DCIP3D, GRAV3D, MAG3D, GG3D, BININV3D, and AMP3D.