STUDENT’S VOICE
The Importance of Utilizing Geospatial Technology and Learning New Technological Skills as a Future Geologist
Danny Foley, SA-8517
df467@nau.edu
With the world and today’s job market changing at an ever- increasing rate, geologists must adapt to stay competitive. As all of the easy geologic problems have been solved and readily available resources have been found, in the future geologic jobs will involve complex problems involving big datasets. Even for aspects of geology that traditionally have been rather straightforward such as field mapping, to shed light on more enigmatic regional scale problems geologists will need a bet- ter understanding of geospatial relationships. Therefore, the merging of geographic and geological sciences will be of key interest to those geoscientists who, early in their career, are trying to make an impact on the field. This purpose of this article is to demonstrate how learning new technological skills such as Geographic Information Systems (GIS) can be a power- ful tool for geologists to develop a better field strategy before ever setting foot on the ground.
My research was on the Ancestral Rocky Mountains (ARM), whose formation remains one of the most poorly understood major tectonic episodes in the Phanerozoic geologic his- tory of North America. Several researchers have presented wide-ranging hypotheses concerning the structural style and tectonic setting of the ARM system. The two main models to explain the ARM are: (1) continental-continental collision along the Ouachita-Marathon Gondwana suture, inferred to cause compressional deformation from the east and southeast (Kluth and Coney, 1981), or (2) an Andean style convergent subduction zone under the Pacific margin of North America causing deformation proceeding from the southwest (Ye et al., 1996). Although there are several uncertainties with ARM formation, mountain uplift and associated basin formation is accepted to be Pennsylvanian to early Permian in age and to be coeval with a major deformational event. My hypothesis was to test whether the major deformation mechanism was from the southeast or from the southwest by determining if a trend in timing of uplift across the region can be measured.
To determine which hypothesis is correct by looking for evidence of the relative east-west or west-east trend of ARM uplift and basin formation, I proposed to radioisotopically date Pennsylvanian-Permian sedimentary rocks shed from the core ARM region. The use of detrital zircon geochronology coupled with thermochronology using U-Pb and U-Th-He methods may help to constrain the timing of ARM tectonics. However, most of the ARM uplifts and basin deposits have been buried, eroded away, and tectonically reactivated, with significant thermal alteration during more recent igneous events. This
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thermal alteration makes selecting sample location sites prob- lematic for radioisotopic study and I therefore learned how to incorporate GIS-based geospatial analytical techniques into sample selection.
To reduce cost and time in locating the Pennsylvanian- Permian siliciclastic rocks within Colorado and adjacent mountain states best suited for ARM radioisotopic study, I developed a sampling strategy utilizing GIS to facilitate selection of the most ideal rocks for analysis. This first involved vector analysis to isolate all Pennsylvanian-Permian siliciclastic rocks and all Pre-Cambrian Basement rocks in the ARM region. Then, the distance of Pennsylvanian-Permian strata from ARM Precambrian basement rock was measured. From this knowledge proximal and distal zones were identi- fied using buffer spatial analytical tools. Next, the proximity to more recent igneous activity was mapped to help avoid radiometric thermal alteration complications for radioisotopic study. In preparation for efficient field analysis, the vector data in sample area was combined with raster based analysis to prioritize the most accessible locations. This was done by using high resolution Digital Elevation Model (DEM) data of key sample zones to assess the least hazardous slopes in the desired terrain. Then the slope spatial analytical tool was used to calculate percent gradient from the DEM at 30 m resolu- tion. The gradient map was output using a color ramp, and this map was used as an overlay on geologic maps to enable increased field productivity.
This comprehensive geospatial analysis will help to effi- ciently identify future sample locations having a robust ARM signature and help to reduce the likelihood of taking samples with thermal alteration complications that may inhibit radio- isotopic analysis. In addition, the remote sensing methodology used in this study may further help other geology related stud- ies beyond the Pennsylvanian-Permian and southern Rocky Mountain region.
Initial results from this study were used to identify medi- um to course grained siliciclastic rock within the western Ancestral Uncompahgre and eastern Ancestral Front Range uplift zones. Taking into account the presence of accessible slopes, as well as proximity to post-Permian surficial igneous activity, I have selected the area around Pitkin, CO as an ideal sample locality to begin field work to test whether ARM defor- mation proceeded from east to west or west to east (Figure 1). With this knowledge in advance of fieldwork, I can prioritize sampling of the Maroon and Gothic formations in this area
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