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.

The BC Geophysical Society and Geoscience BC are proud to present the 2018 BCGS Fall Symposium “Geophysics for Mineral Systems Thinking”

Many world-class mineral deposits are known to lie above geophysical and geochemical anomalies in the lithospheric mantle. The new paradigm in mineral exploration for such large-scale deposits, driven primarily by the Australian experience, is to image the whole lithosphere looking for those geophysical and geochemical anomalies and in particular to map the fluid pathways through which mantle derived fluids pass upwards through the crust. This approach, of mapping the whole mineral system, is one that leads very effectively to discovery of significant deposits through developing understanding of the whole system. In this new paradigm large-scale geophysics has a crucial role to play in the identification and definition of geologic systems on a regional scale, which can have an enhanced expectation of being the location of resources:  minerals, petroleum, diamonds and geothermal.

Symposium Schedule: BCGS 2018 Fall Symposium Schedule

Symposium Abstract Booklet: BCGS 2018 Fall Symposium Abstracts

Please register in advance of the symposium. Your registration can only be guaranteed once payment has been received. The attendee name must be entered for registration to be complete.

Thank you for your strong support. We have sold out! Registration is now closed.

Co-Chairs: Joel Jansen, Anglo American and Alan Jones, Complete MT Solutions

Introduction By: Gavin Dirom, President and CEO, Geoscience BC

Speakers:

Katherine Boggs, Mount Royal University – From LITHOPROBE through EarthScope to the new pan-Canadian EON-ROSE Research Initiatives; Geologic Implications for Mineral Exploration across North America

Fred Cook, University of Calgary (emeritus) – Geophysical, Geochemical and Geological Targeting Potential Mineral Deposits: From Lithospheric Scale to a 5-cm Drill Core

Fiona Ann Darbyshire, Université du Québec à Montréal – Regional-scale natural-source seismology and the cratonic lithosphere

David Eaton, University of Calgary – Tectonic architecture in the Canadian Cordillera: Potential insights from CCArray seismological studies

Randy Enkin, GSC-Pacific, NRCan – Petrophysics for Mineral Exploration: Linking Geophysics and Alteration Geology

Alan Jones, Complete MT Solutions  – Keynote: Mineral systems mapping using magnetotellurics: Examples from Canada and Australia

Henry Lyatsky, Exploration Consultant – Exploration Uses of Regional Gravity and Magnetic Data: Examples from Province-Scale Work in Alberta

Ben Murphy, Oregon State University – How Long-Period EarthScope MT Data Might Inform Targeted Mineral Exploration in the Central United States

Andrew Schaeffer , GSC-Pacific, NRCan – Probing the diamond potential of the North American Lithosphere using seismic tomography

Adam Schultz, Oregon State University – Detailed studies of geothermal and volcanic systems by combining EarthScope long-period MT USArray data with higher-resolution wideband MT arrays embedded in the larger array

Richard Smith, Laurentian University – Geophysical exploration for mineral systems: highlights from the NSERC-CMIC Footprints Project and CFREF Metal Earth Project

Martyn Unsworth, University of Alberta – Lithospheric resistivity structure of Western Canada from long-period magnetotelluric data

BCGS Technical Talk – March 15, 2018

Speaker: Obone Sepato, Anglo American

Title: Density and magnetic susceptibility data of the Bushveld Complex, South Africa

Date/Time: Wednesday, March 15, 2018 @ 4:30pm PST

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

Abstract:

The Bushveld Complex (BC) is the largest known layered intrusion. This suite of rock crop out in northern South Africa to form the Western, Eastern and Northern Limbs. Most research carried out focuses on the mineralized horizons in the Rustenburg Layered Suite (RLS) of the BC. This study presents a large database of wireline geophysical logs across a substantive part of the stratigraphy of the RLS of the West- and Eastern Limbs. These consist of density and magnetic susceptibility datasets sampled at 1 cm. The major lithologies of the RLS intersected in the boreholes presented are gabbro, gabbronorite, pyroxenite, norite and anorthosite whose density histograms reveal that they are predominantly normally distributed, with density averages of 2.86-3.2 g/cm³. The magnetic susceptibility for these lithologies has a large variation from 10^-7 to 13.2 SI with distributions that are multi-modal and asymmetric, which is typical of large layered mafic intrusions. Cross-correlation plots between density and magnetic susceptibility for several boreholes show that the above-mentioned lithologies form clusters (circular to elliptical), which typically overlap. This has been further investigated using k-means classification, to automatically detect these to create a semi-automatic lithology logging system, which has been particularly successful in boreholes from the Eastern Limb.

The final analysis carried out was using wavelet analysis across individual locations in the BC. This has revealed multi-scale cyclicity in all of the boreholes studied, which is attributed to subtle layering created by variations in modal proportions between plagioclase and pyroxene. In addition to this, since layering is generally ubiquitous across layered intrusions, this cyclicity can be assumed to be present across the entire BC. This technique may become increasingly important should the cyclicity in physical property data correlate with reversals in fractionation (demonstrated in the Northern Limb thus far) trends since this may suggest zones of magma addition, challenging the current perspective of four major magma additions as opposed to smaller periodic influxes of magma for the creation of this intrusion.