Applied Geophysics Geology 319 / 829 Professor: Gerhard Pratt pratt@geol.queensu.ca TA’s: Rie Kamei, Drew Brenders Calendar Description: Techniques of geophysics (including gravity, magnetic, electrical, and seismic) applied to engineering problems, including resource exploration and site investigation. Physical principles, instrumentation, field procedures, data interpretation, and design of field programs are covered for each of the major methods. Web Page: geol.queensu.ca/people/pratt/geol319 Username: geol319 To find out the password, send me an email!

Course objectives To train you for your future careers as geoscientists, geological engineers and mineral explorationists To allow you to be informed enough to make use of those geophysical techniques appropriate for your applications To allow you to be able to speak knowledgeably to both your contractors and your managers, about geophysical surveys To allow you to be innovative if there is a new problem that might lend itself to geophysical methods. In some cases, this may be the last applied geophysics course you take --- if so, use this opportunity to consolidate your geophysical knowledge, your career will be enriched as a result. In other cases you may proceed to more advanced courses in which you will learn about geophysics at deeper level --- this course gives you the basis on which to do this.

Geol 249 (Geophysical characterization) Pre-requisites Geol 249 (Geophysical characterization) Math 226, 227 (diff eqs, vector calculus) I don't think that Applied geophysics can be effectively learned without some mathematics. None of the objectives listed above are possible without using a mathematical language to describe the physics of the measurements. The mathematics that are required are at the second year university level (calculus, ordinary differential equations, vector analysis and vector calculus). If you are very unsure about mathematics, there is a good review textbook that will help you to get the required background. It is Mathematics: A simple tool for geologists, by David Waltham (Chapman and Hall, 2000).

Other geophysics courses at Queen’s Geol 249: Geophysical characterization of the Earth. Winter term. Geology 349: Applications of quantitative analysis in geological engineering. Winter term. Geology 409: Applied geophysics laboratory: Fall term, alternate years. Geology 429: Geophysical signal analysis. Winter term, alternate years. Geology 479: Potential field and electromagnetic methods. Winter term, alternate years. Geology 489: Seismic methods: Winter term, alternate years.

Geology 409 Applied Geophysics Lab

Geology 409 Applied Geophysics Lab

Geology 409 Applied Geophysics Lab

Course structure Gravity and magnetic field methods (4 weeks) Gravity: Regional, basin studies, salt diaperism, intrusives, sand and gravel deposits, depth to bedrock Magnetics: Airborne mapping, intrusives, sea floor spreading, mineral deposits, environmental hazards, archeology 1 out of 4

Course structure Electrical methods (4 weeks) 2 out of 4 Resistivity: Mineral prospecting, hydrogeology, contaminants, construction sites, groundwater mapping Induced polarization: Disseminated minerals, aquifer mapping, contaminant mapping Self potential: Mineral prospecting, hydrogeology, geothermal studies 2 out of 4

Course structure Electromagnetic methods (4 weeks) 3 out of 4 Electromagnetic: Deep mineral prospecting, airborne surveys, groundwater studies, subsurface pipes and cables, agricultural studies Radar: Shallow sedimentary structures, water table mapping, depth to bedrock, faulting, contaminant mapping 3 out of 4

Course structure Seismic methods (4 weeks) 3 out of 4 Earthquakes, microseismics: Active seismic zones, structural fabric, imaging Refraction: Mapping and imaging from crustal scales through to engineering scales Reflection: High resolution imaging from crustal scales to engineering scales, primary method in oil and gas exploration, increasingly used in mineral exploration and production 3 out of 4

Assessment Geol 319 Assignments 25% Mid-term exam 15% Final exam 55% Class participation, quizzes etc 5%

Memo to all: come to class!

Textbooks P.V. Sharma, Environmental and Engineering Geophysics. Cambridge University Press. (Suitable for students specializing in Geo-environmental or Geotechnical Engineering. A new, very well written book, at the intermediate level. Examples are specific to environmental and engineering geophysics. This book is so well written that I would encourage all interested students to own a copy). 1 out of 3

Textbooks Kearey and Brooks, Introduction to Geophysical Exploration, Blackwells. (Suitable for students specializing in Mineral Exploration. A less advanced book, but contains well written introductory material to most methods). 2 out of 3

Textbooks Telford, W.M., Geldart, L.P, and Sheriff, R.E. Applied Geophysics, Second Edition. Cambridge University Press, 1990. (Suitable for students specializing in Geophysics. In the past this was considered a very complete reference textbook, but it is becoming somewhat dated. In sections it tends to be overly mathematical, but it does have many examples of geophysical data in a wide range of applications. For descriptions of the engineering principles of geophysical sensors it is unrivaled). 3 out of 3

Definitions of Geophysics The study of the earth by quantitative physical method, especially by seismic reflection and refraction, gravity, magnetic, electrical, electromagnetic, and radioactivity methods. The application of physical principles to studies of the earth. Includes the branches of (a) seismology … (b) geothermometry …); (c) hydrology … (d) physical oceanography; (e) meteorology; (f) gravity and geodesy … (g) atmospheric electricity and terrestrial magnetism … (h) tectonophysics … and (i) exploration and engineering geophysics. Exploration geophysics is the use of seismic, gravity, magnetic, electrical, electromagnetic, etc., methods in the search for oil, gas, minerals, water, etc., with the objective of economic exploitation. Source: Robert E. Sheriff (an explorationist!)

Definitions of Geophysics Geophysics is: The subsurface site characterization of the geology, geological structure, groundwater, contamination, and human artifacts beneath the Earth's surface, based on the lateral and vertical mapping of physical property variations that are remotely sensed using non-invasive technologies. Many of these technologies are traditionally used for exploration of economic materials such as groundwater, metals, and hydrocarbons. Geophysics is: The non-invasive investigation of subsurface conditions in the Earth through measuring, analyzing and interpreting physical fields at the surface. Some studies are used to determine what is directly below the surface (the upper meter or so); other investigations extend to depths of 10's of meters or more. Source: Environmental and Engineering Geophysical Society (not explorationists!)

Definitions of Geophysics “… the application of physical theories and measurements to discover the properties of the earth.” (Society of Exploration Geophysics)

Is this Geophysics? “… the application of physical theories and measurements to discover the properties of the earth.”

Gravity field central Britain Gravity data respond largely to areas of uplift, low gravity over sedimentary basins

Magnetic field central Britain Magnetic field data respond to tectonic fabric, due to the redistribution of magnetite rich rocks near major fault zones Highland boundary fault separates the Scottish Highlands in the North, from the lowlands. The highlands are rugged areas of Cambrian and Precambrian rocks, uplifted during the Caledonian orogeny.

Landfill siting by electrical conductivity High conductivity glacial clays have been scoured, resulting in a decrease in conductivity.

Sedimentary structures Subaerial unconformity – underlying cross-stratified shoreface deposits, and overlying fluvial deposits

Sedimentary structures: Seismic reflection images Subaerial unconformity (red line) – truncation of underlying refressive shallow-marine strata. From Catuneaunu “Principles of Sequence stratigraphy”

Three dimensional seismic surveys in oil and gas exploration Gulf of Mexico survey, showing a salt dome with associated “rim syncline”

Seismic “time slices” in oil and gas exploration Seismic time slice from a 3-D survey in the Gulf of Thailand, showing a meandering stream channel.

Interpretation and identification of drilling targets in oil and gas exploration Prograding delta system within the Gulf of Thailand, based on interpretation of seismic time slices

Sedimentary structures: Seismic reflection images Subaerial unconformity at the base of the Early Cretaceous Mannville Group. High sinuosity fluvial channels are incised into the underlying carbonate structures.

Gravity imaging of impact craters The impact crater on the right is buried below 1 km of sedimentary cover

Gravity imaging of sedimentary basins The Weald basin in Southern England (courtesy Black Rock Petroleum Co)

Gravity imaging of mineral deposits The Darnley Bay anomaly, Northwest Territories, thought to be caused by an intrusive ultramafic body, hosting a major Nickel / Copper deposit

Magnetic field imaging of mineral deposits The Darnley Bay anomaly, Northwest Territories, thought to be caused by an intrusive ultramafic body, hosting a major Nickel / Copper deposit

Magnetic field imaging of mineral deposits The Sudbury basin is now thought to have been caused by a meteorite impact more than 2 billion years ago.

Gravity imaging at an abandoned building site An example of the location of a suspected building foundation

Applied Geophysics Geology 319 / 829 Professor: Gerhard Pratt pratt@geol.queensu.ca TA’s: Rie Kamei, Drew Brenders Calendar Description: Techniques of geophysics (including gravity, magnetic, electrical, and seismic) applied to engineering problems, including resource exploration and site investigation. Physical principles, instrumentation, field procedures, data interpretation, and design of field programs are covered for each of the major methods. Web Page: geol.queensu.ca/people/pratt/geol319 Username: geol319 To find out the password, send me an email!