STRATMODEL MANUAL - FAULT MODELS This Manual is designed as a guide to assist in the creation and interpretation of a Fault Model using Minescapes Stratmodel package.

1.0 Collection of Fault Data in the Field

All faults that are mapped in the field, that is, original outcrop locations prior to any man-made disturbances, or those mapped in disturbed areas, such as road cuttings and mining areas, must be appropriately named, measured (strike, dip and offset recorded), surveyed, sketched and photographed.

The fault data collected from a particular area needs to be collated into a

single Data Table similar to that shown on the next page.

This table can be used for reference during data entry and modeling.

2.0 Presentation of Fault Data

All this fault data must then be recorded into an Outcrop Log (for each individual fault or sets of faults) similar to that shown on page 3.

These detailed Outcrop Logs can later be used as an interpretative guide

for those persons responsible for fault data entry and modeling.

These logs may also serve as a great guide to those who may not have visited the field or mine location, but are responsible for reviewing the computer modeling and carrying out mine planning.

3.0 Fault Conventions used in Stratmodel

Before creating faults, one should be aware of some simple fault conventions used by Stratmodel.

These conventions are as follows:

a. A fault is line string element, which can contain up to 500 vertices; b. Associated with each vertex are throw and dip values; c. A dip angle must be entered for each vertex or a dip of 90o is assumed; d. The throw need only be entered for vertices which have existing data;

Excel Spreadsheet

Outcrop Log

e. The change in throw values along a fault should be gradual to prevent stepping effects in the modeling;

f. The upthrown block is always to the right hand side of the first point entered, looking from start to end of the fault (see below);

g. If the dip angle entered is less than 90o then a Reverse Fault is created

and if the dip angle entered is greater than 90o then a Normal Fault is created (see below);

Dip >90o

Down Up Down

Up

Dip

h. In order for conventions (f) and (g) to work positive throws (see below) must always be entered, because if not, then the opposite will apply. Unless a fault is known to be regional then a value of 0 (null) should be entered for the fault end point vertices or else Minescape will continue the extrapolation (to infinity) and this may then interfere with areas known to be undisturbed by faulting;

i. In the case of Branch Faults care should be taken to assign exactly the

same coordinate at the junction of the two faults. When two faults share the same trace, a cumulative throw is calculated (see below);

j. All faults which are created must also be included in the Model Schema.

Fault 1 and 2 must have the same coordinate

0

8

49

9

59

0

Fault 1

0 3

5

0

Fault 2

Cumulative Throw = 14m

Throw = 8m

End Point

End Point

0 4

5

0

4.0 Creating Faults in Stratmodel There are various methods that can be used to create faults using Stratmodel.

The preferred method involves the following steps:

i. In Stratmodel click on the Open Write File icon which will reveal the Open Current Write window as shown below, you will need to select the Surface Design File and click OK.

ii. Right click on the Current Design Layer window, and then left click on

Create to open the Create Design File Layer window. You will then need to enter a Layer name, e.g. Faults. You should also create a layer called Blank, which is to remain empty.

iii. At the top of the Stratmodel page you should then click on Faults, followed by Create (as shown below).

This will open the following form:

Under the Fault Header sub-divider you must enter the following: Faults Design File. The design file in which the faults are stored,

namely the Surface Design File. Fault Name. Enter the name of the fault. A preferable naming

method is to use an abbreviated name of a deposit or pit area, followed by a number, e.g. Kresna Pit, Fault 22 = K_F22.

Description. This is optional. Fault Layer. The output layer name, which was defined in the

previous step, e.g. Faults. Fault Extent. This is optional. Fault Era. This is optional. Fault Strike. This is optional.

Under the Fault Vertices sub-divider you must remember: That a fault can be maintained by a list of X, Y, and Z coordinates

with a throw and dip at each vertex. To apply the Stratmodel Fault Conventions (as were discussed on

previous pages).

Under the Fault Vertices sub-divider you must enter the following: Easting. Fault X coordinate. Northing. Fault Y coordinate. Elevation. Fault Z coordinate. This is very important for inclined

faults, not so for vertical faults. Throw. Fault offset (in current units of DEPTH). Optional. Dip. The dip of the fault. You must remember the Stratmodel Fault

Conventions.

Survey data (X, Y, Z coordinates) can either be manually entered into the Fault Vertices columns or you chose the Pick Vertex option if you wish to select known points (previously inputted/ imported from another source). Manual data entry: Generally, most faults will only have a single reference point representing the location at which the fault was mapped and surveyed in the field (refer to the Data Table on page 2). The quickest way to create a fault having a single data point is as follows:

Refer to the Data Table for the X, Y and Z coordinates. Enter the known coordinates in Row 2 and then enter a vertex

100m north and south of that point, i.e. use the same Easting and add/ subtract 100m from the known Northing (see below).

Enter the same Elevation for the three vertices. Then click OK to create the fault and the following will appear on

the screen (click V to highlight the fault vertices).

Left click on the Draw Line icon and then right click on the known vertex of the fault (second vertex). This will reveal as shown below.

Select the Keyin Angle option to reveal the following data entry

box at the base of the page.

Enter the known strike of the fault in the Angle box, e.g. 45.

Then left click anywhere on the Stratmodel page to reveal:

You can then create a line running through the known vertex by left clicking either side of the vertex. The length of this segment will depend upon intended length of fault extrapolation.

Then click the letter Q twice to terminate the process (see end

result below).

You then have to move the end point vertices so that they align with the newly created line segment. Left click on the Edit icon followed by the Vertices icon to reveal the following.

Then click on the top of the Vertices window, so this window will

tear off on its own (see below).

Left click on Move to reveal the prompt, Pick a vertex to move, then double click on an end point and then move (drag) this point so that it aligns with the line segment.

.

Repeat this process for the second end point, so that the fault now aligns with the line segment. Delete the line segment.

Select Fault, then Edit to open the window shown below.

You can now update the Elevation data so that all 3 vertices are the same, plus you can enter the Throw (use 0 for the end points, as explained in the Fault Conventions) and Dip (use positive numbers and remember that for Reverse Faults you must enter a dip 90o) data as well.

Left click OK to complete. You can then click on the icon to show the fault annotations (see below).

To understand what these annotations mean in relation to the various fault conventions, please refer to the following examples: Reverse Fault Strike of 045o, dipping 50oNW

Normal Fault Strike of 045o, dipping 50oNW

Reverse Fault Strike of 045o, dipping 50oSE

Normal Fault Strike of 045o, dipping 50oSE

In each of the four examples given on the previous two pages it is important to observe the vertices order (from start to finish) plus the inputted dip angle (less than or greater than 90o) used to produce either a normal or reverse fault having the correct dip direction.

Please note if you create a fault and then realise that the fault vertices order is inappropriate for the fault you wish to model you can reverse the vertices direction by using the Reverse command in the Vertices Tear-off box.

Simply left click on Reverse then double click the fault trace and the

vertices order will be reversed, as will the fault annotation.

An Important Note: As mentioned previously for most faults you generally only have a single reference point at which you can create the fault trace. However, on occasions especially within a mining environment you will be able to map the same fault at several locations, e.g. down a pit highwall, across the pit floor, in the side walls of advancing blocks, in road cuttings or in creek / river diversion channels. It is important to remember the following:

Always use the same fault name for the same fault, e.g. K_F22. You can add fault vertices by clicking Insert in the Vertices Tear-off. In the case of inclined faults make allowances for dip variations (at

different elevations) when trying to create or extend a fault along strike.

5.0 Modeling Faults Using Stratmodel Upon the completion of creating or updating faults in the Surface Design File, the Model Schema must then be updated:

i. Left click on Schemas, then activate the Edit command.

ii. In Edit a Schema left click on the Faults Tab-divider.

iii. Under the Faults Tab-divider you must enter the following:

Fault Sequence. The name of the conformable sequence to be entered. If the Top Unit or Bottom Unit are entered this is not required.

Top Unit. Name of the Top Unit to which a given fault applies. If top and

bottom units are defined then the fault is applied to these and all the intermediate units. If only the Top Unit is defined then the fault is only applied to that unit. If no units are defined the fault will be applied to all units within the Fault Sequence.

Bottom Unit. Name of the Bottom Unit to which a given fault applies. If top and bottom units are defined then the fault is applied to these and all the intermediate units. If only the Bottom Unit is defined then the fault is only applied to that unit. If no units are defined the fault will be applied to all units within the Fault Sequence.

Fault Name. The name of each individual fault. Faults are applied by

conformable sequence and faults affecting multiple sequences must be defined for each conformable sequence intersected by the fault.

iv. Once you have completed editing the Model Schema click on Apply or OK.

v. You will then need to re-process the Stratigraphic Table Model

followed by the Stratigraphic Grid Model (as per normal modeling procedure) in order to create a new Fault Model.

Once the Grid Model has completed running you are now ready to interpret and edit the Fault Model.

6.0 Interpreting and Editing a Fault Model Prior to commencing any Fault Model interpretation and editing work there are some very important points to consider:

The Stratmodel computer operator must have a solid 3-D geological understanding of a particular deposit or mine site before being able to interpret and edit a computer generated Model that contains faults, especially a model that contains multiple faults.

Such an understanding of a deposit or mine area will only come about by

having being present in the field either during the exploration drilling program or by having made regular visits to a pit or underground area during the actual mining process.

The reason being is that the computer operator ultimately has to interpret, edit and generate a 3-D model that reflects both the stratigraphical (sedimentary bedding) and structural (faults and folds) features of the deposit that are observed in the field.

Personnel not involved in the collection of field data may find it very difficult to generate a realistic model without the assistance of those who were present on the actual work site and were responsible for drilling or mining supervision plus data collection.

Competent Geological Reports, Outcrop Logs and Data Tables supplied by the geological field team as well as constructive conversations with site-based personnel will also be of valuable assistance to those not present in the field.

Please note that the ability of the Stratmodel operator to develop or possess sound 3-D geological interpretative skills is imperative towards being able to successfully use software to create a representative Fault Model.

A suggested method on how to interpret a Fault Model is as follows: A. Compare the Fault Traces with Topographical Features

i. Open the Faults layer within the Surface Design File and then attach the Topography Design File by clicking on the icon to reveal the Attach Reference window (below).

ii. Scroll down to the required Source File e.g. topo_oct03, then click Next.

iii. Nominate the topography layer(s) that you wish to include in the model

review and then click Finish.

iv. The Stratmodel Page should now be similar to that shown below.

By observing the page above you will be able to recognise several topographical trends/ lineaments plus river and creek locations that may in fact relate to structural features such as folding and faulting. It is very important to recognise distinct topographical features as they may in fact be the surface expression of sub-surface fault zones.

v. For an example, a close-up of the window on the previous page shows that there is a relationship between the interpreted strike of three fault traces and different topographical features, as shown below. Field visits to areas such as those shown below will also assist in identifying such relationships between topography and fault traces.

vi. Left click on the icon to reveal the Detach Reference window

(below).

Left click on the Topography Design File and then OK. This will clear the screen, leaving just the Surface Design File.

B. Compare Fault Traces with Drill Hole Locations

i. Attach the Drill Holes Design File by clicking on the icon to reveal the Attach Reference window (below).

ii. Scroll down to the required Source File e.g. dholes, then click Next.

iii. Nominate the drill hole layer(s) that you wish to include in the model

review and then click Finish.

iv. The Stratmodel Page should now resemble as shown below.

v. By observing the page above you will be able to identify potential drill holes in which coal seam intersections that may be transected by faults.

vi. Another way of recognising whether or not faults may intersect drill

holes is to check the Daily Field Reports or the individual drill hole geology and geophysical logs which may also indicate the presence of faulting in drill holes. A good example is coal seam repetition within a drill hole which is indicative of reverse faulting.

C. Create Cross Section Lines

i. The next important step is to create a set of cross section lines (may have already done so prior to adding faults to the geological model). Whilst still in the same Stratmodel Page as that shown on the previous

page, click on the Open Write File icon, to reveal the following:

ii. Select the section Design File and OK. If these section lines have already been created the following the will appear if the appropriate layer(s) is chosen.

If no layer(s) exist within the Sections Design File, then you will need to create a layer(s). Please note that these cross section lines should be approximately perpendicular to the strike of the deposit being modeled and the spacing between these sections (usually 100-200m) will depend upon the drill hole spacing and the total strike length of the deposit.

iii. In order to create a set of section lines you must firstly draw a single

line, by clicking on the icon and then draw a line perpendicular to the strike of the deposit along a drill hole section using the mouse (click the Q letter-key to terminate the line) as shown below:

iv. Then click Edit > Copy > Parallel as shown below:

v. Double click on the section line created above and then drag the cursor (mouse) in the direction you wish to create the set of section lines:

vi. Left click when you have dragged the cursor the required distance and

this will the following box in the lower corner of the Stratmodel Page:

vii. You will need to enter the required Spacing between each section line

(in metres) and the number of section Replications. Once you have done this left click on the CAD Window and the following will appear:

viii. In the bottom right corner of the Stratmodel Page there is a command to Select element to copy, you must do this by double-clicking on the section line created previously. As a result the following will appear:

Once you have created a set of section lines, using the method described on the previous pages you are now ready to generate a set of geological cross sections. D. Generate a Set of Geological Cross Sections i. This is done by selecting Graphics > Section > Stratmodel at the

top of the Stratmodel Page:

ii. This reveal the Create a Section through a Schema window:

iii. You must then enter data into each of the Tab-dividers. IO Tab-divider

The relevant Schema information. Input information such as Topography, the name of the Drill Hole

Design File and the Drill Hole Search Layers (need to select all layers you wish to correlate with the geology model).

Output information, namely the Design File (e.g. sect2d) and

Default Layer (e.g. xsects) in which the cross sections are to appear.

Sections tab-divider The ID or Section Name, which can be found by right clicking on

the blank ID box, then left clicking Pick which will revert to the CAD Window (shown on the previous page) in which you can select each section line on a one-by-one basis.

As these section lines are numbered you can also manually enter

each ID, however be careful as sometimes Stratmodel can change the numbering sequence, so it is better to Pick this sections to make sure the correct IDs are entered.

Output Layer this is layer in which cross sections will appear (it

is the same as that nominated under the IO Tab-divider.

Append enter Yes for the first section line and No for all remaining section lines.

2D X Origin/ 2D Y Origin the output Design File is 2D and as a

result the bottom left corner of each section is assigned an x, y coordinate. To stack the sections on top of each other, keep the x coordinate constant and increment the y origin slightly greater than the section elevation range.

Controls Tab-divider

Section Controls

Select the Orientation grids by ticking the box.

Z Exaggeration used to exaggerate the vertical component of each section.

Grid Z Interval spacing of the horizontal grid lines of each

section.

Grid XY Interval spacing of the vertical grid lines of each section.

Minimum / Maximum Level elevations used to truncate the

surfaces at the top and bottom of each section.

Model Controls

Number of Steps leave blank. Step size if several sections are being created in the same

execution and the section line elements are of varying length, enter a value e.g. 10, to ensure that the sampling increment for all sections is equal.

Drill Hole Controls

Corridor width the search width for each section line, which is generally the same as the section line spacing.

Hole display width preferred width for the display of drill holes.

Use lithologies optional.

Display hole name select this check box to display hole/ unit

names of the graphics as text.

Hole text offset offset distance between the collar and the start of the hole name text in current length units; default is hole collar.

Display unit name select this box to display the name of the

various units as text.

Unit text offset offset distance between the hole and the start of the interval or surface text string in current length units.

Minimum spacing between text for units minimum spacing

between the text names of units, to prevent overplotting of closely drawn units.

Display Tab-divider Section Display

Major grid display definition controlling the graphics attributes

for the major divisions of the orientations grid.

Minor grid display definition controlling the graphics attributes for the minor divisions of the orientations grid.

Model Display

These are sensitised if when the Model check box is selected in the IO Tab-divider.

Fault for a fault model, faults are displayed using a display

definition that controls the graphics attributes for faults. All remaining attributes are optional.

Drill Hole Display

These are sensitised if when the Drill Hole check box is selected in the IO Tab-divider.

Front holes display definition colour used to display holes in the

front of each section line, typically these are displayed as green.

Back holes display definition colour used to display holes behind of each section line, typically these are displayed as red.

Parting optional.

Hole name text display definition controlling the graphics

attribute for the hole name.

Unit name text display definition controlling the graphics attribute for the interval and surface text.

iv. Select OK or Apply to create the cross sections. Stratmodel will commence to generate the geological cross sections.

E. Edit Geological Cross Sections

i. In order to edit the set of geological cross sections, you must now open a new Stratmodel Page. This is done by left clicking on Page > Open Product > Stratmodel, which will reveal a blank page:

ii. The next step is to left click on the Open Write File icon, to reveal the following:

iii. Select the sect2d Design File and OK.

iv. The next step is to left click on the Layers On/ Off icon, to reveal the following:

v. Select the required Search Layer and click OK.

vi. A page similar that shown below will appear:

vii. By moving the mouse to any point on the CAD Window and then selecting the W letter-key followed by moving the mouse once more you can create a box defining an area to be enlarged. When you have defined the necessary enlargement left click again and the zoomed-in area will automatically be revealed, for example:

viii. By clicking on the icon, the fault and seam annotations will be revealed as follows:

Please Note: These annotations will assist in making interpretations between the surface trace of the various faults and the sub-surface offsetting of the coal seams, i.e. you will have to check that the fault modeled is behaving as required (normal or reverse displacement).

ix. It will now be necessary to scroll through all the geological cross

sections created, especially taking note of those sections where drill hole coal seam intersections are located near the sub-surface projection of a fault or faults, as shown in the example below:

x. Another way of checking the cross sections is to generate an A0-size paper plot (or plots) so that you can review several cross sections simultaneously. It is much easier to view and correlate multiple cross sections on a paper plot than it is to do so, on a computer screen. This paper plot method will greatly assist in recognising zones that may have been disturbed by faulting and is recommended as opposed to scrolling through the sections individually on the computer screen.

At this point it is very important to remember the following:

A. In order to achieve the desired interpretation for each cross section and the Fault Model as a whole it may be necessary to:

Slightly change the position of the faults surface trace by using the mouse to drag a fault vertex(s) to a new position in the Surface Design File; or

By using the Faults > Edit function to change either the dip angle

and/ or the throw of a fault so that both the fault and drill hole data correlate.

B. That this stage of model interpretation work will take considerable time to achieve the necessary results. The actual time taken will depend upon:

The validity of the drill hole data supplied from the field (given that valid seam names were applied to the various coal seams);

The total number of drill holes in the model database;

Actual coal seam continuities (which is related to the depositional

and sedimentation processes);

The accuracy and validity of the supplied fault data;

The number of faults in the model database;

The number of drill holes intersected by faults (indicated either by coal seam repetitions, missing coal seams or variations in over-/ interburden thicknesses);

The number of cross sections generated (this relates to the strike

extent of the deposit and the drill hole spacing); and

Ultimately the interpretative skills of the personnel responsible for Fault Model interpretation and modification.

C. Further steps that may need to be used to achieve model success:

Drill holes containing coal seam repetitions need to be split into A and B composites, i.e. these holes need to be split into two separate holes in order to model coal seam repetitions above and below a reverse fault.

This is done by creating a second hole which has the same easting

and northing as the original hole but a different elevation (the Depth From and Depth To values also need to be adjusted accordingly). See the example shown below:

Apart from creating a second hole to model the seam repetitions, either the surface trace or the dip and throw of the fault intersecting the split drill holes must also be adjusted to suit the model:

This adjustment process may take several attempts i.e. you have to re-run the cross sections each time to see the changes you have made and whether or not they are acceptable.

Another method that can be used achieve model success is to

generate a set of long sections (use the same procedures as described previously to create a set of section lines and then a set of vertical sections). This enables the user to view a deposit along strike and also assists in recognising structural features that may be orientated perpendicular to the strike of the deposit as shown below:

xi. After all checks are completed and you are confident that the

interpreted Fault Model reflects the actual geological structure of the deposit you are modeling then it is necessary to re-process the Stratigraphic Table Model followed by the Stratigraphic Grid Model (as per normal modeling procedure) in order to produce a final Fault Model.

xii. This Fault Model is now ready to be used for calculating mining

resource and reserve estimates plus it can also be used for short, medium and long term mine planning purposes.