Date of Award

5-2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Geology

First Advisor

William Gosnold

Abstract

Using the spatiotemporal record of the 2.1–0 Ma ignimbrite flare-up of the Yellowstone Plateau Volcanic Field (YPVF) as a proxy for batholith formation at depth, this dissertation develops and applies the Finite Difference Heat Flow Simulation (FDHFS) program to model crustal thermal evolution beneath the supervolcano. FDHFS, a modular C++ numerical simulator, solves the transient heat equation incorporating variable thermal conductivity, radiogenic heat production, and directional advection in three-dimensional Cartesian grids. Validation against analytical benchmarks and seafloor-spreading analogs confirms its fidelity for combined conduction-advection processes in heterogeneous crustal settings.

High-resolution volume–time analysis of major ignimbrite pulses (Huckleberry Ridge, Mesa Falls, and Lava Creek Tuffs) reveals episodic extrusion rates (0.003–0.0245 km³ yr⁻¹) up to an order of magnitude higher than the long-term average (0.002 km³ yr⁻¹). Inversion using 3:1 to 5:1 plutonic:volcanic ratios yields peak intrusion rates of 0.009–0.1225 km³ yr⁻¹, documenting the incremental assembly of an estimated 12,990–21,650 km³ of granitic material in the upper crust (5–17 km depth).

Two-dimensional FDHFS simulations illustrate how sustained plume-driven heat input elevates geotherms, crosses the rhyolite solidus at shallow depths, and shallows the brittle–ductile transition through progressive crustal weakening. These results establish a positive thermomechanical feedback between mantle power input, temperature elevation, mechanical failure, and the accumulation of larger rhyolitic magma bodies. The nested caldera architecture further records composite pluton construction over multi-million-year timescales.

Collectively, the findings reinforce the generality of episodic, thermally modulated batholith construction across tectonic settings and provide a robust framework for interpreting active magmatic systems, volcanic hazards, and geothermal resources.

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