An oriented drill hole is one where the inclination and azimuth of all sectors of the hole axis are known, usually by means of a special down-hole survey. This data provides the inclination and azimuth of the longitudinal axis (the Core Axis, CA) of the cylindrical core of rock that […]
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Summary Measuring the attitude of structures in drill core requires fully oriented core. But the tools for orienting core that are currently available to drillers often fail, especially with small core diameters (NQ or less) and where the rock has fissile surfaces within it. As these failures […]
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Here’s the thing You know what Australia looks like. You would recognise it on a map: its general shape, the peninsulas, the great gulfs. You could draw it from memory, probably, and if you did, it might look something like this: Figure 1 That’s a pretty […]
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The definition of a geological fault, and why most dictionaries get it wrong One of the most important structures for any mineral explorer to understand are faults. What, exactly, is a fault? To geologists the answer seems so obvious that few of them (even the writers of many […]
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The movement of faults Faults are not mathematical planes (2D surfaces with length and depth but no thickness) but 3D tabular zones of deformed rock. The length and depth of a fault is always much greater than its thickness, but fault width can vary through many orders […]
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Stereonet solutions for non oriented drill core Shawn Harvey of Saskatchewan sent me this email earlier this year: Hello again Roger, You previously helped me out with some alpha-beta stereonet solutions which worked great (thanks again!!). I am now looking into a slightly more complex stereonet issue. […]
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Using a stereonet to calculate strike and dip from alpha-beta angles in oriented drill core The attitude of a surface in oriented drill core can be determined by the measuring two internal core angles known as alpha (α) and beta (β). These numbers are then normally entered […]
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Sense of Movement Structures in Fault Zones. Part 3: Identification criteria Within or adjacent to a fault zone, various minor structures can be present that enable the sense of movement across the fault to be determined. These structures are often called kinematic indicators. In Part 1 of […]
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Sense of Movement Structures in Fault Zones : Part 2 – Examples Within or adjacent to fault zones, various minor associated structures can be present that enable the sense of movement across the fault to be determined. These structures are often called kinematic indicators. This is the […]
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