Structural Mapping Techniques and Tools
In Chapter 2 we ‘find our bearings’ in order to locate outcrops in the field and construct maps of geological structures. Geographic coordinates are used by the Global Positioning System (GPS) for location (see above) and the Universal Transverse Mercator (UTM) projection is used to project geographic information from Earth's curved surface onto a piece of paper. We describe a modern mapping campaign that utilized GPS technology to create a precise structure contour map in a region where four sets of faults intersect to disrupt and fold the surrounding strata. The mapping was accomplished in a fraction of the time and with much greater control than previously possible. We anticipate a new generation of structural maps that will provide the impetus for more specific modeling of tectonic processes and the data to better constrain those models.
Concepts from Chapter 2
These exercises explore concepts from Chapter 2 including the gnomonic and Mercator projections, 2- and 3-dimensional transformation of coordinates, and use of the equal angle stereonet to plot the orientations of planar and linear structural elements.
Mapping dikes at Ship Rock
This exercise introduces the position vector for mapping geological contacts and the translation and rotation of a local coordinate system to a map with standardized coordinates. The thickness variations along a dike also are examined to investigate physical mechanisms operating during emplacement of the magma.
Mapping faults at Chimney Rock
In this exercise we consider basic concepts and tools for mapping geological structures and for analyzing the orientations of linear and planar structural elements. Both structural maps and stereographic projections are prepared using ten data sets for faults from Chimney Rock, Utah. The spherical variance is used to evaluate the clustering of orientation data.
Kinematics of faulting at Chimney Rock
The kinematics of faulting are examined at Chimney Rock, Utah. Slickenlines on exposed fault surfaces are used to analyze the direction of slip and to investigate how these directions vary along a fault. Structure contours are constructed from GPS data for the Carmel and Navajo formations and these are used to identify faults and to measure the magnitude of slip.
The following button links to a folder in Box where images from the text and images that are supplementary to those found in the text live.
The following button links to a folder in Box where MATLAB scripts (.m) geared for the MATLAB editor live.