Manual_Micomine_Drillholes

MICROMINE Version 11.0 Training

Part 7 – Drillholes 1

PART 7 TABLE OF CONTENTS LESSON 1 – PRELIMINARY PRELIMINARY DRILLHOLE DRILLHOLE INVESTIGATION INVESTIGATION ................................. .................................................. ................................ ...............1 INTRODUCTION ................................ ................................................. .................................. ................................... ................................... .................................. ................................. ................ 1 DRILLING STATISTICS ................................. .................................................. .................................. .................................. .................................. .................................. ......................... ........ 1 GETTING MORE (OR LESS) FROM DRILLHOLE D ATA ................................ ................................................. .................................. .................................. ......................... ........ 5 LESSON 2 – SUMMARISING SUMMARISING DRILLING DRILLING RESULTS RESULTS .................... ..................................... .................................. .................................. ...................... .....10 INTRODUCTION ................................ ................................................. .................................. ................................... ................................... .................................. ............................... .............. 10 ONE-RECORD-PER -HOLE SUMMARIES................................. .................................................. .................................. .................................. .................................. ....................... ...... 11 Example Exampless ................................... .................................................... .................................. .................................. .................................. .................................. ............................... .............. 11 MULTIPLE-RECORDS-PER -HOLE SUMMARIES ................................ .................................................. ................................... .................................. ............................... .............. 15 Example Exampless ................................... .................................................... .................................. .................................. .................................. .................................. ............................... .............. 15 LESSON 3 – CREATING DRILLHOLE LOGS LOGS.................................. .................................................... ................................... .................................. ................... .. 22 INTRODUCTION ................................ ................................................. .................................. ................................... ................................... .................................. ............................... .............. 22 Log display vs. extraction ................................................................................................................ 27

SIDEBARS An alternative alternative way way to calculate calculate drillhole drillhole summary summary statistics............... statistics........................ .................. ................... ................... .................. .................. ............. .... 3 Identifying properties with irregular boundaries ......................................................................................... 6

Copyright © Micromine 2009

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Revision 2009-05D1




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Revision 2009-05D1



Lesson 1 – 1 – Preliminary Drillhole Investigation


Notes:

Duration: XX minutes The geologist in charge of a drilling programme is commonly asked one of two questions while the programme is under way: how many holes have been drilled totalling how many metres, and what significant intervals were intersected? This and the following lessons will teach you the tools needed to generate both results. This lesson will teach you to prepare basic summaries of data held in drillhole databases. After this this lesson you will be able able to: •

Create summaries of holes drilled and total depths;

•

Summarise assay statistics;

•

Create distributions of assay data.

Introduction As well as displaying displaying data MICROMINE MICROMINE has many functions that manipulate drillhole data. These functions are located in the Drillhole Drillhole menu mainly in the Calculations and Calculations and Compositing sub-menus. Compositing sub-menus. There are also a number of data manipulation functions, commonly applied to drilling information, that are located in the File | Fields | … menu. … menu. Note that you cannot use any file manipulation functions that create new values and fields on ODBC or Microsoft Access or GBIS linked files. However, these linked files can be saved as DATA files prior to use.

Drilling Statistics In the following exercise you’ll generate basic drillhole summary statistics, comprising the number of holes drilled and their total length.

Exercise 1.1: Generate drillhole summary statistics To count the number of holes and total number of metres found within the Example drillhole data: 1.

Select Drillhole | Calculations Calculations | Extraction from Extraction from the main menu.

1.

Select EXAMPLE_COLLAR as as the Input File. File.


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Notes:


2.

Modify the file to add a CALC field, Numeric, 6 Characters 0 decimals. Enter 1 in the START field of the Modify Form and Close. This will replicate the value in all records.

3.

Set up the dialog as indicated below:

4.

On the Drillhole Extraction dialog note the following:

•

•

•

•

5.

Constant field 1 = CALC. The function reads the file from the top and performs the action selected in the Extraction type window on successive records that have the same value in this field. Extraction type = SUM. This tells the function to calculate the total of all the numeric fields. By checking the Use other extraction types and selecting the CALC field to extract the SUM, the function will total the values in this field, which equals the number of drillholes in the file. If you are operating on the whole file (no Filter set) this step is not strictly necessary as the number of holes in the file will equal the number of records in the file. This step is used to write the total number of holes in the Output file so it can be used as required for other reporting purposes. The Character field output can be any of the options. Run the function and examine the output file, shown here (some fields have been hidden for clarity):

The fields of interest are TDEPTH, which contains the sum of the drillhole depths, and CALC, which contains the number of drillholes in the file.

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The other numbers are meaningless and may be hidden or removed as required.


Notes:

Note that you cannot perform this operation on the EXAMPLE_ASSAY interval file and get the correct answer. The maximum TO value is not necessarily the total depth of a drillhole. This information is only located in a properly verified collar file. In the next exercise you’ll use the statistical tools of MICROMINE to calculate some basic information about the assay data.

Exercise 1.2: Generate basic assay statistics Before commencing any detailed analysis of an assay interval file you can use the basic statistics functions to determine the range of values and various estimates of the median and mode of the values. This is a basic part of the data validation process. Validation of a drillhole database checks the relationship between files and interval values; it does not check the assay values. This process is concerned with discovering gross errors in the data, i.e. that no values in a percentage field are outside the range 0-100. 1.

Select Stats | Descriptive | Normal/Ln from the main menu.

2.

Select EXAMPLE_ASSAY as the Input File.

3.

Click the Fields... button, set the Weighting field to INTERVAL and the first two Field Names to AU1 and AG. There is no need to set Min, Max, or Cut Values.

4.

Click the Numeric Exceptions button and set all three exceptions.

5.

Enter EXAMPLE_ASSAY_DES_STATS as the Output file and Run the function.

6.

MICROMINE will calculate and display a range of statistics for each field, which you can browse by clicking the Next or Previous buttons.

7.

Close the Descriptive Statistics dialog and then right-click the Output file response. Note the contents of the file, which reproduce the information originally displayed on the dialog.

An alternative way to calculate drillhole summary statistics You can also use Descriptive Statistics to generate the holes and metres report from Exercise 1.1. In this case, use EXAMPLE_COLLAR as the Input File and TDEPTH as the Field Name. No. of points represents the number of holes, and the Sum the total metres drilled. The disadvantage of this method is the output cannot be used as th e input for any other report or calculation, whereas the output from Drillhole Extraction can.


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Notes:


In the workplace you should examine the values for each field to determine if they are within the expected range. In the next exercise you’ll display a histogram of the assay data, which will reveal the statistical distribution of the values.

Exercise 1.3: Generate distribution statistics of assay data Further examine the EXAMPLE_ASSAY file by graphically displaying the distribution of values. This is another way of validating data, and a preliminary step in the resource calculation process. To do this: 1.

Select Stats | Distribution from the main menu.

2.

Set the Input File to EXAMPLE_ASSAY and the Graph field to AU1.

3.

Click the Numeric Exceptions button and set all three exceptions.

4.

Set the Graph type to HISTOGRAM and the Values used to NATURAL LOG.

5.

Click the Graph Limits button and set the options as listed here: Prompt

Setting

Graph min:

[Double-click to set]

End first bin:

blank

Bin size:

3

Graph max:

[Double-click to set]

Graph increment:

blank

6.

Click the Graph Options button set Graph colour and Line colour to red, the Normal curve colour to green, set all options, set Display mode to LINE and Line type to SOLID.

7.

Click the Analysis button, select any six Population colours, and set a contrasting Model colour.

8.

Save the form and Run the function. Your display should resemble the diagram on the following page.

9.

Optionally experiment with different values to see their effect on the display.

You can improve the display of NATURAL LOG data by manually setting the Graph min to the lowest data value (usually the detection limit). Notice also that from the graphic display a new menu line is displayed at the top of the screen. The Mode menu allows you to switch between Histogram, Cumulative Frequency (Cum freq) and Probability Plot (Prob plot) displays.

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Notes:

Clicking on the graph will display the Bin number, Min and Max value for the bin, its Centroid value and the number of Points in the bin within the Information Box at the right of the screen. The Model menu option allows you to statistically Decompose the data into the separate populations that may be contained within it, or to fit a 3 Parameter model to remove bias from NATRAUL LOG values. A histogram allows you to determine if there is more than one population within the sample. This in turn requires you to identify the limits of each population, either geographically of statistically, so each can be modelled separately for anomaly definition, or for resource calculation. Further detailed analysis of the distribution of samples is beyond the limits of this course. For more information on using the histogram, refer to Part 14 – Statistical Essentials, which is part of the Advanced Exploration or Block Modelling course.

Getting More (or Less) from Drillhole Data Sometimes you need to divide your drillhole data in a way that makes it easier to separate different groups of drillholes by a parameter such as their coordinate values, the name of the property they’re within, or their drill date. In the next two exercises you’ll learn how to set up your data for this kind of use.


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Notes:


Exercise 1.4: Use more than one drillhole database In this exercise you’ll learn to prepare different drillhole databases from the same data files in order to accomplish different objectives.

Step 1: determine how to classify the drillhole data Assume that a large amount of drilling data is available over a large landholding. In the process of exploring this area, prospects in separate geographical areas have been discovered and drilled in detail. It makes sense to create separate drillhole databases for these different areas. The EXAMPLE_COLLAR file contains a PROPERTY field, which is currently empty. You’ll use that to classify the drillholes according to their coordinate. 1.

Open EXAMPLE_COLLAR and apply a filter (Filter | Edit Filter from the Editor menu) that defines North >= 15880. Be sure to set the Condition as Numeric.

2.

Click Save and Close to apply the filter, and then select Filter | Use Filtered Records (or press Ctrl+F4) to restrict the following step to just the filtered records.

3.

Enter the text NORTH in the first filtered PROPERTY record and press Ctrl+R to replicate that value to the end of the file. All collars north of 15880 are now marked in the PROPERTY field.

4.

Invert the filter and use the same technique to enter SOUTH into the remaining PROPERTY records.

Identifying properties with irregular boundaries In the workplace, different property boundaries are usually stored as polygons in either a GIS application or MICROMINE. You can use those polygons to assign the property names to the collar file using the Modelling | Assign Outlines function.

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5.

Select Drillhole | Database | Create from the main menu to set up a database called PROSPECTS using the settings in the diagram on the following page.

6.

Optionally, Use EXAMPLE_EVENTS as an Event File.

7.

Use EXAMPLE_ASSAY and EXAMPLE_LITH as interval files.




Notes:

8.

Click OK to create the PROSPECTS database.

This database is different from the EXAMPLE database because it uses an attribute in the file to allow definition of two different prospects (NORTH and SOUTH), which can be selected on the Drillhole Trace dialog in Vizex. To display the different prospects do the following: 9.

Double-click Drillhole Trace in the Vizex Form Sets pane and select PROSPECTS as the Database. Set up a simple plan trace display using the EXAMPLE_LITH file, and save it as a form set with the Title Drillholes by prospect.

10. After displaying the plan, double-click the Drillholes by prospect Display layer to reopen the Drillhole Trace dialog. 11. Switch to the Input Data tab and set the Filter checkbox. Right click the blank filter response to display the DHDB Filter Setup dialog. 12. If a filter has already been created, select New from the pop-up menu. 13. Pull down the first Field Name list and select ATTRIBUTE FIELD 1, which you previously configured to contain the PROPERTY information. 14. Enter NORTH in the Value field and Save this as a form set with the Title North Prospect.


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Notes:

15. Repeat the process to define another filter that uses SOUTH as the Value, and save that as a form set titled South Prospect. Now that you’ve defined how the drillholes will be separated into the NORTH and SOUTH prospects, you’ll display holes from the individual prospects in the next exercise.

Exercise 1.5: Filter drillhole data Exercise 1.4 took the drilling data and separated it into two geographical areas. All that’s needed to display the different prospects is to use one of the database filters you just created.

Switch between the NORTH and SOUTH displays A database filter is similar to an ordinary MICROMINE filter. It is only applied to the collar file used when the database is defined; this means you only have to select the database name when applying a filter. To apply the database filter:

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1.

Reopen the Drillholes by prospect form if it is not already open.

2.

Set the Filter checkbox (if it is not already set), double-click the filter response, and select the North prospect form set.

3.

Click OK to display only the drillholes north of 15880N.

4.

Repeat the above steps to display the drillholes south of 15880N.




Notes:

Lesson 1 Summary This lesson has shown you how to use a drillhole database to selectively display data. A collection of drill data can be grouped or classified in a variety of ways depending on the outcome required. The topics covered are: Using more than one drillhole database definition. Identifying what data to display. Define classification values in the collar file. Setting filters using the classifications. Displaying different database views. Filters are only applied to the collar file. Move between displays by selecting different filters.

Good Practice Using filters on a database is better practice than trying to maintain separate collar and other data files for different prospects. There is only one version of the collar file for a large area. Areas that are initially recognised as separate prospects can overlap with further drilling. All that is necessary to reclassify drillholes is to change the values in the collar file that identify the prospect.

Help Topics For information on:

See:

Creating a Drillhole Database

Drillholes > Drillhole databases > Using drillhole databases

Filtering a Drillhole Database

Drillholes > Drillhole databases > Filtering drillhole databases


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Notes:


Lesson 2 – Summarising Drilling Results Duration: XX minutes This lesson will teach you to prepare single record and multiple record summaries from different drillhole files. Exploration drilling results are commonly manipulated prior to display. After this lesson you’ll be able to: •

Extract bottom of hole assays;

•

Determine minimum, maximum and weighted average values;

•

Merge extracted data from assay or geology files back to collar files.

Introduction The techniques described here are some examples of the calculations and extractions that can be made using the Drillhole |Calculations | Extraction function. This is an extremely versatile function; its use is not confined to drillhole interval data files but can be used on any suitably sorted file. Drillhole interval data must be sorted by HOLE ID, then by ascending FROM values. When Drillhole Extraction is used on a drillhole interval file the HOLE ID field (e.g. HOLE) is used as Constant field 1. When you run this function to, say, extract the highest assay in a field for every hole, MICROMINE reads through every record in the file from the top and finds, for each hole, the record with the maximum value. When the HOLE ID changes the record with the highest assay is written to the Output file. This process is repeated with variations as changes are made to the form. If a lithology field is selected as Constant field 2 and the function is Run to extract average values, it will calculate the average grade of each lithology interval for each hole and write that to the output file. Special handling is available for character fields. Special handling can also be applied to individual numeric fields; the function can extract any mix of extraction types for different fields. Other data files, such as block model files, can be examined through this function. If you wanted to extract the top and bottom elevation of columns of equal sized blocks in order to create a DTM surface you would first sort the block model by North, East and RL, in that order. Then use North as Constant field 1, East as Constant field 2 and extract successively the Maximum and Minimum RL to different files. Now add and subtract half the block size to the Top and Bottom RL values and use these points to create a DTM or Grid. Page 7.10



One-record-per-hole Summaries


Notes:

The following exercises extract one-record-per-drillhole by performing the selected action sequentially from the start of the file on every record in the file (unless a filter is applied). The grouping, or classification, is created by constant values in successive records in one or more of the Constant fields. The most common examples of one-record-per-hole summarise include: •

End-of-hole values Extracts the record from the bottom sample in each drillhole. Commonly used to plot Bottom_of_Hole geology from exploration drilling.

•

Minima, maxima, or weighted averages Extracts the record with the maximum value of a selected field for each drillhole. Commonly used to generate grids or contours of geochemical data.

Merging extracted data with collar coordinates The initial step of a process with the object of adding values to a field in a collar or other file based on some value in an assay, lithology or event file. For example, prior to block modelling it is necessary to identify the holes that contain samples that are part of a particular domain. Domains are commonly defined by wireframes, which are Assigned to interval files. Extraction of single records that identify these domains is necessary so that they can either be applied as a Filter or merged to a file that identifies multiple records that can be used as input to a process.

Exercise 2.1: Extract the end-of-hole L I T H Typical of this type of extraction is creating plan displays of bottom of hole lithology. 1.

Select Drillhole | Calculations | Extraction form and select or enter values shown in the diagram on the following page.

Although this is an interval file it is not necessary to enter the From and To field names.


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Notes:

2.

Run the function and examine the Output file, which will resemble this:

3.

Notice that record 2 has a blank LITH value. This is caused by a missing value in the original file.

4.

To overcome this set the filter shown on the following page in the Drillhole Extraction dialog.

This filter forces the extraction to operate on records that have a LITH value. This means the value extracted is not the lithology of the bottom of the hole but rather the last record in each hole with a LITH value.

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Notes:

5.

Re-Run the function and inspect the modified Output file.

6.

Save the Drillhole Extraction form as a form set Titled EOH Lith.

Exercise 2.2: Extract maximum AU 1 from the EXAMPLE_ASSY file: 1.

Modify the Drillhole Extraction form and select or enter values as follows:


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Notes:


2.

Examine the Output file. This extraction writes the complete record that contains the maximum AU1 value for each hole.

Variations on this extraction could include using the LITH field as Constant field 2; which would output the maximum AU1 value for each separate lithology. 3.

Save the Drillhole Extraction form as a form set Titled Max AU1.

The extracted file records may contain coordinates but these will not correspond to the collar of the associated drillhole. Even vertical holes will contain elevation differences. In the next exercise you’ll merge the extracted information back into the collar file so you can create a plan display showing the distribution of values.

Exercise 2.3: Merge extractions to the collar coordinates One record per hole summaries are usually merged back to the collar file for display purposes. 1.

Open and then Modify the EXAMPLE_COLLAR file to add the following fields: BOH_LITH C 10 0 MAX_AU1 N 8 2

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2.

Select Edit | Tools | Merge | MM from the Editor menu, or click the Merge Menu button followed by MM, to display the Merge dialog, and fill it out as shown here:

3.

Click the Merge Fields button and select the following:




Notes:

4.

Click the Merge button to write the EOH_LITH values to the BOH_LITH field in the EXAMPLE_COLLAR file.

5.

Repeat the above steps to merge the AU1 value from the NVG_MAX_AU1 file into the MAX_AU1 field in the EXAMPLE_COLLAR file.

6.

Optionally, display the collars as a Vizex Points layer, colouring by BOH_LITH (using the Lithology colours colour set) or MAX_AU1 (using the Drillhole Au1 statistical colour set) as desired.

Multiple-records-per-hole Summaries Examples of multiple-records-per-hole summaries are: •

Simplified lithology Generates a simplified lithological file from typical field logging in which logging is carried out at fixed sample intervals, causing long geological intervals to be repeated over several samples.

•

Significant intersections Extracts composited intersections above a specified cut-off or threshold value. Minimum interval length and inclusion of waste material can be used to finely control the output.

•

Gram-metre values Uses the extracted average grade and accumulated interval length to calculate a length-grade product.


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Notes:

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Exercise 2.4: Create a lithology file from field sample records 1.

Select Drillhole | Calculations | Extraction from the main menu and fill out the form as follows:

2.

Open EXAMPLE_FIELD_LOG to view the input file.

3.

This is a typical field log as prepared with the Micromine FIELD MARSHAL program, or imported from another file editor.



The geologic fields LITH and ALT will be used to create the lithology log file. The LITH field contains the rock type codes and is the primary field, the ALT field contains codes for the weathering intensity.


Notes:

The INTERVAL field does not have values entered. This type of file normally contains regular intervals as defined by the FROM-TO values, the field is only used for the composited output file. 4.

The form as shown above will generate composited records from samples where both the values in the LITH and ALT fields are the same in successive records.

5.

Note that the INTERVAL value has been calculated and written to the file. The SAMPLE value written to the file will be the character string from the FIRST record of the group.

6. An interesting feature of this dialog is that it will produce the same output regardless of the Extraction type selection ( SUBUNIT excepted). 7.

If there is only one geology interval use the Drillhole | Compositing | Geology menu with the following setup:


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Notes:

8.

Note that this dialog does not have the exception handling or calculation functions of the Drillhole | Extraction menu. This process will create the following output:

9.

Once this and other files of this type are created it is good practice to modify the files to delete the spurious and incorrect fields such as SAMPLE so they will not be used improperly.

Exercise 2.5: Extract AU1 assays over 0.8 g/t To a significant intersections file, write each contiguous interval to a separate record. Calculate the gram-metre values for each output interval.

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1.

Select Drillhole | Calculation | Extraction from the main menu and select or enter values as follows:

2.

The filter in this case is set to Au1 > 0.8 with the Numeric checkbox set. This will calculate intersections where all the intervals are greater than 0.8 g/t.

3.

Setting the Maximum gap length to a value less than the smallest sample interval causes the function to exclude intervals that are excluded by the filter.

4.

The thickness of each interval will be calculated and written to the INTERVAL field. This is done by entering the following in the Use other extraction types More....



Notes:

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Notes:


5.

Note that the above process is not compositing assays, it is extracting selected records and doing various mathematical operation on them. Compositing is examined in detail in Part 12 – Drillholes 2.

Exercise 2.6: Calculate the gram-metre product of the extraction intervals Once the calculation is complete, open the Output file for editing in order to calculate the gram - meter product.

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1.

Click on the Calculator icon to open the following form:

2.

The result field, G_M will be created by the function and the product will be written to this field.




Notes:

Lesson 2 Summary This lesson has shown you how to extract required records from an interval file and use the extracted records to calculate required values. Extractions are based on Numeric or Character fields and can be performed with any suitable file. Topics covered are: Calculate significant intersections: Set a filter to identify the values to be extracted; Use the other extraction type dialog to perform different operations on some fields; Calculate further values from extracted files: Extracted values can be used to derive values that are not present in the original files by using the editor Calculator or similar tools.

Good Practice Use this dialog any time you have to create summaries from existing files. Among the output you can produce is: •

Maximum assay value per hole

•

Maximum assay values in different lithologies for each hole

•

Sums of values for selected holes

•

Weighted averages across various intervals

Help Topics For information on:

See:

Drillhole Calculations

Drillhole extractions >Drillhole extraction calculations

Drillhole Calculations

Drillhole extractions > Example Extractions


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Notes:


Lesson 3 – Creating Drillhole Logs Duration: XX minutes This lesson will teach you how to display values of individual drillholes on the screen and interactively identify, calculate and display intersection values. After this lesson you’ll be able to: •

Display individual drillholes as graphic logs;

•

Calculate multiple intersections and write them to a file;

•

Output individual logs as plots.

Introduction There are many ways to calculate and display drillhole intersections, automatic compositing is covered in Part 12 – Drillholes 2. This lesson allows you display individual holes and values on the screen and graphically select the intervals to be composited. Results are written to a separate file, which can then be displayed beside the individual holes. Multiple intersections can be interpreted for each hole but must be arranged from the top to the bottom of the hole, and intersections cannot overlap.

Exercise 3.1: Set up a log display Select Drillhole | Log | Intersections from the main menu. This function allows you to totally control the display of individual drillholes. The following display is but one example that can be displayed. A can be made between Hatch, Graph, Intersection and Multi-field Once displayed a new menu line opens that allows starting and depths to be selected while MICROMINE calculates and displays average interval intersections.

selection displays. stopping weighted

Additionally there is a Strip Log dialog that enables users to display up to ten different fields in a choice of formats. Plots of all these displays can be prepared.

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Notes:

This display is prepared using the following dialog:

Because of the number of choices available the preferred method of laying out the display is to create the hole trace with its reference scale, then add Copyright © Micromine 2009

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Notes:


the required selection of values, events, hatches graphs, intersections and multi-field displays. The display does not reference a Vizex drillhole database so the required files must be individually selected. 1.

The Collar file and Collar Fields identify hole location and hole depth.

2.

Hole ID identifies the drill hole to be displayed. If no list file is selected the holes will be displayed in the order they appear in the Collar file.

3. A List file can be selected. If used this controls the sequence in which the holes are displayed. It can contain as little as one field, to contain the Hole ID. If selected, the Collar file must also be selected as this contains the coordinate and depth information. 4.

The Downhole reference scale enables the display of downhole depths.

Display limits 5.

The Min and Max depth fields contain the range of downhole depths to be displayed. The Min is commonly blank and the Max should be equal to the depth of the deepest hole.

6.

The X range field defines the relative horizontal width of the display. The left hand margin of the display is always at a value of zero. Commonly a value of 100 is used, the position of the other display features are then defined using values between 0 and 100.

7.

The Trace X location requires a value for the position of the vertical drillhole trace. In the above display 10 is used.

Display 8.

The Hole Annotation dialog controls the parameters of the top and bottom hole information . Collar coordinate displays can be suppressed by inserting the @ symbol in the relevant field.

9.

The Trace, Value, Events, Hatch and Graph dialogs allow you to select information to be displayed. These are standard MICROMINE objects and will not be described in detail. Each requires an offset location measured from the reference position followed by display values.

Exercise 3.2: Interactively measure significant intersections Once the basic display is prepared you can interactively calculate and display intersections on screen and write them to a separate file, as well as write a code identifying the intersection back to the interval file.

Calculate intersections 1.

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To calculate and display length-weighted intersections check the Calculate intersections prompt and open the dialog.




Notes:

2. •

•

•

•

There are four possible Run modes: OUTPUT INTERSECTION: Calculated intersection written only to the Output File. Code field in Input File is disabled. ASSIGN CODE: Output File disabled, Code is written to the Code field of the Input File. OUTPUT & ASSIGN: Calculated intersection is written to the Output File and Code is written to Code field in Input File. DISPLAY ONLY : Output to screen only.

3.

The Input File is an interval file that contains values to be calculated and a Code field to which an identifier will be written. Up to six fields can be selected for calculation.

4.

When you select Gaps = missing the length of the sample of any missing value in any field over an interval is treated as NULL for averaging. When you clear it, the interval is included in the averaging and treated as if it had a value of zero.

5.

The Output File must exist. It is usually created by copying the structure if the Input File. The Thick field will receive the width of the intersection.

Display output To display the results of the calculation you must check at least one of the Intersect/MF 1 boxes in the Display group. There are two possible Display mode settings. The MULTIFIELDS option is only used for displaying existing data; select the INTERSECTIONS option to display the results of the calculations. 1.

The Input File will normally be the Output File that was defined in Calculate Intersections dialog.


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Notes:


2.

In the Thickness Annotation box enter the text that will follow the thickness value i.e. metres.

3.

The Side list controls placement relative to the trace.

4.

The Field box allows selection of the values to display. This can include character fields to enable constructions like 3.2 metres at 23.5 g/t Au to be created where the metres at and the g/t Au components are contained in different fields. Use the Justify options and the Width values to format the output.

5.

The Label box controls the delimiters that appear between the values and their Colour, the Offset distance and the Size factor. The Size factor will not be reflected on the display screen but will be written to any plot file and will be reflected in the output.

6.

The Ticks box enables control and placement of ticks for the calculated intersections. A vertical line joining the left side of the tick marks serves to distinguish intersection displays from multi-field displays.

Making the Calculation 7.

Click on the Run button. MICROMINE will display the graphic log of the hole and a new menu and icon bar.

Regardless of the length of the hole the complete range as defined in the Max depth field will be displayed. To zoom to the complete hole click on the Zoom Hole icon. You can also zoom to any part of the hole using the Zoom menu function which will allow you to click on the upper and lower limits as required. When zoomed in so that not all of the hole is displayed triangles appear at the top and bottom of the trace. The PgUp and PgDn menu items move the display at the current scale when not all the hole is displayed. Prev and Next move to the adjacent holes in the List file (if used). To make a calculation select the Intersect menu. A horizontal red line will appear; use the mouse to move the line to the upper limit of the intersection. Notice that the line will only attach itself to an interval boundary, you cannot subdivide the intervals. Left click to fix the upper boundary then repeat the process to define the lower limit of the interval. Notice that as you move the mouse after the upper limit is selected the Hole, From and To values and the Interval are displayed on the right hand side of the display with the calculated values for each field defined. Left click on the lower boundary. An Output intersection to file? Query appears. Select Yes to write the complete intersection to the Output File. A Key in code prompt appears, enter the identifier of the interval then OK . This will add the code to the Output File and prompt for Another Intersection? Continue to add intersections as required. Note that you should create the intersections from the top down. You are creating a new interval file; these files must be arranged in order of increasing From values. If you enter intersections out of order they will be written to the Output file, which must then be sorted by Hole and From before it can be used. Page 7.26



Intersections should not overlap. If you require different calculations that will produce overlaps they must be put in different intersection files.


Notes:

Viewing the result Once the intersections have been digitised click on the Refresh button in the Icon bar. This will regenerate the display using the contents of the Output file as defined in the Intersect/MF 1 dialog. The result should resemble the image at the start of the lesson. Click the Next menu item to move to the next drillhole in the List file and select Intersect to process that hole. If you close the Drillhole Intersection Display then run the function again you will be prompted to Overwrite or Append the existing Output file. The default is Append, which will add any new intersections to the existing file. If you select Overwrite the current contents of the file will be deleted.

Log Display vs. Drillhole Extraction The log display is totally under the users control so can be used as an interpretation tool. It allows the user to be somewhat subjective by using any of the displayed information to decide where intersection boundaries to be set. The contrasts with the Drillhole | Calculations | Extraction process that uses a rigorous process of calculating intersection intervals based on fixed values of minimum output thickness and maximum gap lengths, plus other parameters. This loss of interpreted input is balanced by the speed of the extraction process. Hundreds of holes can be calculated quickly whereas the log display requires each intersection to be selected manually. The extraction process provides a consistent set of conditions to the calculation of intersections.


Page 7.27

Manual_Micomine_Drillholes

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