JGP 438 OPTIONAL EXPERIMENTS SECTION (Done as last experiment)
Choices for optional experiments
This demonstrates how gravity or magnetic profiles across anomalous features
can be interpreted quantitively. Specific
instructions are in the handout entitled
P2 Gravity and Magnetic Modelling/Interpretation
Background information is in the Lab Manual: - Gravity and Magnetics chapter (already distributed)
This technique is used a good deal in engineering and environmental studies to
study the layering of shallow strata. Clays, sands and gravels, impermeable igneaous metamorphic rocks, etc., have very different
abilities to conduct electricity, and this makes it possible to differentiate
and locate the formations by electrical measurements made on the earth's
surface.
The field technique is demonstrated on a small scale model in the lab. Data from the experiment and archive data from field surveys are interpreted using the ResInverse computer program.
Read the section Electricity Theory p1-5 in the E and EM Lab notes for background.
This is a scale model simulation of mineral exploration using the resistivity/IP method. An electrical profiling survey is
carried out on the surface of a water + sandbox which contains some hidden
objects. This is somewhat more labour intensive than
the other choices.
The Instruction sheet is entitled:- A resistivity and Induced Polarization Survey of a Laboratory model
Read the E and EM Lab notes Electricity Theory (P1-5) and Electrical Conduction in Rocks (P1-7) sections for background
See the Exercise instructions EM1: - Horizontal Loop EM Method
A scale model study is made of how the HLEM system responds to known conductive objects. Then the model system is used to detect and delineate conductors hidden inside an enclosed space that simulate sulphide mineralized formations.
Read the E and EM Lab Notes Electromagnetic Exploration Methods (P17-29) and A Model of the Horizontal Loop EM Method (P30-31) for background.