Author ORCID Identifier

https://orcid.org/0000-0002-0615-9181

Semester

Spring

Date of Graduation

2026

Document Type

Dissertation

Degree Type

PhD

College

Eberly College of Arts and Sciences

Department

Geology and Geography

Committee Chair

Kathleen Benison

Committee Member

Amy Weislogel

Committee Member

Jaime Toro

Committee Member

Ember Morrissey

Committee Member

Francesco Dela Pierre

Abstract

Knowledge of gypsum textures and the processes that yield them is important for interpreting the history of environments, climates, and life on Earth. This is because gypsum textures are products of specific environmental, microbiological, and diagenetic processes, and because gypsum is relatively common in the Earth’s sedimentary record. Despite this significance, gypsum is relatively understudied. The fundamental goal of this dissertation is to advance our understanding of gypsum textures by presenting detailed, petrography-based investigations of Permo-Triassic gypsum from the continental interior of Pangea.

Gypsum is typical in the Permo-Triassic sedimentary record of tropical Pangea, where it is associated with red beds and halite. A growing body of work investigating these red bed-hosted evaporite deposits reveals parts of Pangea were characterized by saline lake and groundwater systems during a time of profound climate change and significant biological loss. This dissertation presents two new localities of Permo-Triassic continental saline environments, improving our understanding of this widespread and long-lived environmental system.

The first chapter of my dissertation, “Saline lake deposition and complex diagenesis in the Permian Cloud Chief Formation, Texas Panhandle, U.S.A.,” is published in Journal of Sedimentary Research. This manuscript interprets red bed-hosted Permian gypsum from Texas as extensively neomorphosed continental saline lake deposits. In particular, the products of “gypsum dedolomitization,” or partial dolomite replacement of gypsum and subsequent gypsum replacement of dolomite, are documented for the first time in the literature.

The second chapter of my dissertation, “Stromatolite-bearing gypsum lake deposits from the Triassic Red Peak Formation (Chugwater Group) of Wyoming, U.S.A.,” is under revision at Sedimentology. This manuscript interprets red bed-hosted Triassic gypsum from Wyoming as desert saline lake and mudflat deposits; a special focus is given to gypsum stromatolite boundstones, which are described for the first time from the Triassic of Wyoming. In addition to the first petrographic descriptions of Permo-Triassic gypsum lake stromatolites, this manuscript presents the first documentation of syndepositional anhydritization of ancient gypsum.

The third chapter, “Mars-analog sulfate veins host cells and other organic matter,” will be submitted to Journal of Geophysical Research – Planets. This manuscript documents cells and organic compounds preserved within gypsum vein cements from Permo-Triassic red beds.

These chapters together represent several major advances in gypsum sedimentology, including (1) the first documentation of gypsum dedolomitization; (2) the first petrographic descriptions of gypsum stromatolites from Permo-Triassic saline lake deposits; (3) the first documentation of syndepositional anhydritization in ancient saline environments; and (4) the first documentation of cellular material and organic compounds in Mars-analog gypsum veins. In general, this dissertation demonstrates the remarkable textural heterogeneity of ancient gypsum, including micron-scale heterogeneity of complex diagenetic fabrics that had previously been poorly understood. This work highlights the importance of thin section petrography in any future investigation of chemical sedimentary rocks, which are texturally sensitive to environmental and diagenetic conditions.

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