2023
DOCUMENTING
KINEMATICS IN
EXPLORATION AND
MINING PROJECTS – WE
NEED TO DO BETTER!
COMMENTS ON THE NECESSITY FOR HIGHCONFIDENCE RECORDING OF KINEMATIC
RELATIONSHIPS
BRETT DAVIS – OLINDA GOLD PTY LTD
Contents
Contents..........................................................................................................................................................1
Introduction ....................................................................................................................................................2
Apparent movement.......................................................................................................................................2
Documenting kinematics ................................................................................................................................4
DOCUMENTING KINEMATICS IN EXPLORATION AND MINING PROJECTS – WE NEED TO DO BETTER!
| Comments on the necessity for high-confidence recording of kinematic relationships
Introduction
Structural geology is top of the pile when it comes to forming ore deposits. In the exploration and mining
industry, there are many things we do really well, and many things we don’t, with regard to documenting
structural geological relationships. One of the things we don’t do well is the resolution of kinematics.
Understanding the kinematics of structures should be a fundamental skill, and the documentation of the
interpreted kinematics should be a fundamental task. They aren’t.
Knowing the movement history of your structures over time is as important as collecting good quality
planar and linear data. Sadly, the collection of linear data is something else we don’t do well, and
commonly don’t do at all. But I digress. This post is about documenting kinematics. However, very very
very few companies capture this information, and virtually none have the facility to record it in their
databases, other than as a comment.
Apparent movement
Apparent movement and the resultant interpretations vary depending on the direction of viewing and on
the dip of the structures. Apparent movements are a function of not knowing the orientation of the
movement vector and can develop as shown in the figure below.
Development of apparent movement relationships
DOCUMENTING KINEMATICS IN EXPLORATION AND MINING PROJECTS – WE NEED TO DO BETTER!
| Comments on the necessity for high-confidence recording of kinematic relationships
Structures are never planar, so they can go from hosting an apparent reverse sense to hosting an
apparent normal sense if the dip direction changes. The incorrect terminology will hinder the correlation
of structures. For example, the same fault is less likely to be correctly linked if it is called a reverse fault at
one location and a normal fault at another one. I’ve posted on this before and unashamedly repeat the
diagrams here. Clearly, the same fault is present in each of the diagrams. However, the interpretations
vary markedly, depending on location.
Faults are never straight. Use of 'normal' and 'reverse' terminology is not good practice wihen
dealing with steep structures that change dip direction.
DOCUMENTING KINEMATICS IN EXPLORATION AND MINING PROJECTS – WE NEED TO DO BETTER!
| Comments on the necessity for high-confidence recording of kinematic relationships
The use of terminology that doesn't include a unique movement sense (e.g. top-side-south) can
complicate understanding models, tectonic understanding etc
Documenting kinematics
To resolve the movement sense, we require well developed kinematic indicators and the orientation of
the movement vector. The photo collage posted below shows asymmetric foliations in gold-chlorite schist
(bottom left), asymmetric distribution of chalcopyrite-bearing strain shadows adjacent to gold-bearing
pyrite (top right), and asymmetric gold-bearing pyrite grains in non-coaxial shears (top left and bottom
right). These are just a few of the many kinematic indicators that don’t get documented.
Some microstructural kinematic indicators from West Australian gold deposits. The bottom left
image is from Sunrise Dam, the other three are from Kanowna Belle.
DOCUMENTING KINEMATICS IN EXPLORATION AND MINING PROJECTS – WE NEED TO DO BETTER!
| Comments on the necessity for high-confidence recording of kinematic relationships
To document kinematics unambiguously in our database, we need to divide the kinematic information
into two separate columns – one for movement in plan and one for movement in section. We then need
to say which way one block has moved relative to the other e.g. E-block-down, S-side-up, top-to-thenorth etc. To document structures as reverse or normal is not good practice, because this apparent
movement can change over short distances. So, someone’s reverse fault can be the same as someone
else’s normal fault, as shown above.
The division of kinematics into consistent relative motions allows for filtering of the information. For
example, it may only be S-side-up structures that accommodated movement in a particular deformation
that are mineralised. Similarly, if we see movements nominated in both columns, we know we are
dealing with oblique movement at that point and we can check to see if there is a lineation/movement
vector that supports this.
I have included an extract from one of my spreadsheets, showing kinematics documented in plan (Sin =
sinistral) and section (S-dn = south-side-down) in the box on the right-hand side of the figure.
Division of kinematic information into sectional and map movement senses.
At the end of the day, people may differ on how to capture this information. However, currently 99% of
databases haven’t even gotten to that point. It’s something we really should improve on.
DOCUMENTING KINEMATICS IN EXPLORATION AND MINING PROJECTS – WE NEED TO DO BETTER!
| Comments on the necessity for high-confidence recording of kinematic relationships