Department
Geosciences and Geological and Petroleum Engineering
Major
Geology and Geophysics
Research Advisor
Wronkiewicz, David J.
Advisor's Department
Geosciences and Geological and Petroleum Engineering
Funding Source
Geology and Geophysics Program
Abstract
The weathering of rocks is dependent on the mineral composition, climate, and tectonic environment. Goldich (1938) determined the relative weathering rate of minerals in igneous rocks was inversely proportional to their crystallization temperature (i.e. Bowen's Reaction Series). To test this relationship, we sampled weathered and unweathered granite, rhyolite and basalt rocks from the St. Francois Mountains, MO area. The samples were crushed, pulverized, and pressed into pellets suitable for X-ray diffraction (XRD) and X-ray fluorescence (XRF) analysis. XRD and microscopic analysis showed that the K-feldspar within the granite and rhyolite samples weathered to illite and kaolinite clays. From unweathered to weathered granite, our XRF data showed there was a residual enrichment of Al (from 15 to 27 wt.%), the Si content was conserved (from 70 to 65 wt.%), the K content decreased slightly (from 6.8 to 5.1 wt.%), and the presence of Na and Mn were below detection. XRD and microscopic analysis on the basalt sample showed an unusual enrichment of K, which weathered to illite and smectite, and the presence of weathered TiO2 product, anatase. Analytical results of XRF on the basalt and rhyolite will be discussed later in the report. The purpose of this research is to observe the changes of mineral compositions during modern weathering. This can reveal how weathering processes alter over time and during climate change.
Biography
Stephen Houser is a sophomore in geology with a focus in exploratory geology. Stephen is an avid collector of rocks and minerals. He likes the hands on activities related to research in the geological field. This includes the gathering of samples of rocks from mountains and lakes.
Research Category
Sciences
Presentation Type
Poster Presentation
Document Type
Poster
Award
Sciences – section 2 poster presentation, First place
Location
Upper Atrium
Presentation Date
14 Apr 2022, 1:30 pm - 3:00 pm
Mineral Compositional Changes During Weathering
Upper Atrium
The weathering of rocks is dependent on the mineral composition, climate, and tectonic environment. Goldich (1938) determined the relative weathering rate of minerals in igneous rocks was inversely proportional to their crystallization temperature (i.e. Bowen's Reaction Series). To test this relationship, we sampled weathered and unweathered granite, rhyolite and basalt rocks from the St. Francois Mountains, MO area. The samples were crushed, pulverized, and pressed into pellets suitable for X-ray diffraction (XRD) and X-ray fluorescence (XRF) analysis. XRD and microscopic analysis showed that the K-feldspar within the granite and rhyolite samples weathered to illite and kaolinite clays. From unweathered to weathered granite, our XRF data showed there was a residual enrichment of Al (from 15 to 27 wt.%), the Si content was conserved (from 70 to 65 wt.%), the K content decreased slightly (from 6.8 to 5.1 wt.%), and the presence of Na and Mn were below detection. XRD and microscopic analysis on the basalt sample showed an unusual enrichment of K, which weathered to illite and smectite, and the presence of weathered TiO2 product, anatase. Analytical results of XRF on the basalt and rhyolite will be discussed later in the report. The purpose of this research is to observe the changes of mineral compositions during modern weathering. This can reveal how weathering processes alter over time and during climate change.
Comments
Joint project with Rachel Adcock, Mercedes Lane, and Emma Puetz