TARGETING DRILL HOLES It is a truism that ore bodies are rare and hard to locate. If this were not so, they would hardly be worth finding. Explorers search for them by drilling holes into the ground. A single drill hole produces a very small sample […]
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The Three Point Problem In a previous post (see here) I described how quantitative orientation data can be collected from from a single drill hole, even where the core is not oriented. In this post, techniques for collecting orientation data on planes are described when more than one […]
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Measuring Structure in Non-Oriented Drill Core My drill core is not oriented. How do I measure structure? Down-hole orientation surveys record the deviation of a drill hole from its initial azimuth and inclination. However, the solid stick of drill core (sometimes, not so solid) recovered from a […]
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Six rules for alpha beta measurements in drill core It is always better to know the orientation of planar structures at the time of logging rather than at some later date when the structure that was measured is long forgotten and the core returned to its stack in […]
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Visualizing complex objects in three dimensions isn’t easy, although geologists are better at this than most. Two dimensional objects are an order of magnitude easier to comprehend. Where the object under study is complex we can gain an understanding by viewing it on two dimensional slices or […]
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Vergences and fractals Field geologists have long known that the style and relationships of structures seen in a hand specimen, outcrop or drill core can mimic the style and relationships of much larger structures that formed during the same deformation but occur at the scale of a geological […]
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Using Stereonets Cheap, versatile, reliable, compact, robust, ultra lightweight and does not need any batteries: there should be a stereonet in every geologist’s field kit. A stereonet is a tool (a type of nomogram[see footnote 1]) that allows the attitude of planes and lines in three-dimensional space […]
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All metal deposits that have formed later than the rocks that host them (that is, epigenetic deposits) have got there by virtue of fluid transport along faults and their location, shape, size and attitude are largely determined by the strain states that existed within the fault […]
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Strike and dip is a convention for measuring the attitude of a planar structure, such as a bedding plane, fault, joint or vein, in terms of the angles which it makes with the geographic coordinates of the earth’s surface – north-south, east-west and up-down. You probably know […]
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