MODAL ANALYSIS OF SEDIMENTARY ROCK THROUGH HYPERSPECTRAL IMAGING ANALYSIS: APPLICABILITY TO GEOLOGICAL AND PALEONTOLOGICAL/PALEOENVIRONMENTAL STUDIES

The mineralogy of a sediment of rock specimen can provide a variety of valuable information on its origin, modes of transportation to its present locality, depositional environment, and paleoenvironmental conditions. Such findings are valuable in themselves, and provide evidence of changes in sediment sourcing, as well as paleoecological information about fossil taxa present. However, the methods commonly available to petrologists, such as radiochronology, scanning election microscopy, and optical petrographic microscopy, tend to be either difficult, time-consuming, or expensive in their application.

As an alternative, we investigated a rapid application of hyperspectral imaging to sediment modal analysis. Previous applications of hyperspectral imaging to sedimentology and lithology have generally been large-scale qualitative and mapping studies, mainly facilitated with airborne sensors. This study tested the viability of small scale modal testing of sediments (and ultimately, sedimentary rocks.)

We utilized a backpack mounted hyperspectral camera suitable for field study to produce spectra of controlled samples containing a variety of mineralogical compositions that are commonly observed in a field setting. We made qualitative observations concerning the presence of a mineral as a major modal component of a prepared sediment sample, as well as the quantitative modal (mass) percentage of those components. We then compared the results with other samples to identify how multiple minerals with different characteristic reflectance patterns can be used to determine modal composition. This study demonstrates that hyperspectral imaging has potential to act as a method to determine the modal composition of a sediment or sedimentary rock sample quickly and accurately, particularly with respect to sandstones and other siliceous sediments and rock.