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 Department

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

Emma Puetz is a junior at Missouri S&T majoring in Geology, with a focus in Paleontology, and minoring in French. She is the Secretary of C.L Dake Geological Society and an athlete on the S&T Women's Cross Country and Track teams. She is also an Undergraduate Research Assistant in a Materials Department Lab. Her hobbies include running, hiking, travelling, and spending time with her friends and family.

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

Comments

Joint project with Rachel Adcock, Stephan Houser, and Mercedes Lane

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Apr 14th, 1:30 PM Apr 14th, 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.