What are geological structural measurements?
Geological structural measurements record the orientation of features in the Earth's crust, such as bedding planes, faults, folds, fractures, contacts, and foliations. These measurements are fundamental in understanding the spatial distribution of different domains, geological history and the stress regime of an area. They help geologists interpret the geometry and evolution of rock formations, crucial for assessing mineralization controls and structural traps. The structural measurements collected in the field are the backbone of creating geological maps, where these in situ (in place) measurements aid the geologist in creating high confidence maps, while interpreting across areas without exposed outcrop.
How is the data collected?
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Data is typically gathered during fieldwork using instruments like a compass clinometer to measure strike and dip (for planar features such as bedding or faulting) or plunge and trend (for linear features such as fold hinges or mineral lineations on a fault surface) on outcrops, which represent the surface expression of geological features.
Some commonly used terms are:
Strike: refers to the direction of the line formed by the intersection of a geological plane (such as a rock layer, fault, or bedding surface) with a horizontal plane. It is expressed as an angle relative to true north.
Dip: the angle at which the geological plane is inclined from the horizontal. It is measured perpendicular to the strike and indicates how steeply the plane is sloping, along with the direction in which it dips (the dip direction).
Dip direction will always be perpendicular to the strike. A common convention in the geological community is to assume the “Right Hand Rule” (RHR) for dip, whereby if you place your right hand so your fingers point down the dip, your thumb will then point in the direction of the strike.
Sometimes geological data can be recorded with a dip direction and dip, instead of strike and dip. Subtracting 90° from the dip direction will give you your azimuth.
Structural data can also be derived from geophysical interpretations, core logging, or drone and satellite-based photogrammetry, depending on the scale. Recent advancements in LiDAR and photogrammetry allow for the collection of large structural datasets through remote sensing.
What is the support of the data?
Structural measurements are typically documented as point data. Each measurement is taken at a specific location (point) with documentation of the coordinates, elevation, type of structural feature being measured, and orientation (ex. strike and dip). Collectively, these points can be used to generate vectors in 3D space by connecting the individual measurement stations to generate a geological and structural map.
How is this data typically displayed in geoscientific software?
In software like ArcGIS, Geoscience Analyst, or QGIS, geological structural data is displayed as point data (often symbolized with arrows or lines which indicate strike and dip direction) representing the orientation of planar or linear features.
Modifiable display elements:
Vector thickness and color (to highlight certain features).
Orientation symbol (e.g., arrows for dip direction).
3D visualization can be used to project structural data in space, often visualized as discs (see image below).
Data can be filtered by feature type (faults, fractures, folds) or orientation class.
An example of structural point data with strike and dip symbols on a geological map in 2D GIS software:
An example of structural point data with discs representing the strike and dip and classified by geological unit in 3D GIS software:
What does it mean for geologists targeting mineral systems?
Structural measurements are critical in mineral exploration as they often control the emplacement of mineral deposits.
Faults and fractures can act as conduits for hydrothermal fluids, which may precipitate minerals as they cool or react with host rocks. Mineralized veins (often in the form of quartz + sulphides) are critical structures to understand in order to most effectively drill test these targets.
Bedding planes or foliations may serve as markers for geological deformation, helping to target areas where mineralizing fluids are likely concentrated.
Structural data allows geologists to predict the movement of fluids within a system and identify potential traps or dilation zones where mineralization is likely to occur.
The mineral systems approach positions structural data as a fundamental control on fluid flow, metal transport, and deposition. This dataset provides a key layer for building a robust structural framework, crucial for refining exploration targets in mineral-rich environments. For geologists targeting mineral systems, the integration of structural measurements—at both regional and deposit scales—enables the identification of key geological features that control where mineralization occurs. This approach allows for more predictive exploration, reducing uncertainty and guiding geologists towards higher-potential areas within broader mineral systems. By mapping and analyzing structural data, geologists can pinpoint critical areas where ore-forming processes have been concentrated and predict where these processes may have been most effective in forming economic mineral deposits.
How is this used in the DORA targeting workflow?
Structural point data is compiled into a vector shapefile with each data point containing coordinates and elevation (x,y,z), structure type, azimuth/strike, and dip. This data is then used in the preliminary Feature Engineering step to extrapolate the structural orientation fields to areas where no structural data was collected.
The resultant output is a raster map across the area of interest for AI modeling which represents the strike fields of each structural type (faults, bedding, etc.). These rasters are then incorporated into the Data Stack which Predictive Modelling will utilize to generate the VPS (VRIFY Prospectivity Score).
Still have questions?
Reach out to your dedicated DORA Contact or email Support@VRIFY.com for more information.