- Title Information
- Title
- Transitions in Earth’s Convective Regimes: Causes, Styles, and Consequences
- Type of Resource (primo)
- dissertations
- Name:
Personal
- Name Part
- Al Asad, Manar
- Role
- Role Term:
Text
- creator
- Name:
Personal
- Name Part
- Lau, Harriet
- Role
- Role Term:
Text
- Advisor
- Name:
Personal
- Name Part
- Huber, Christian
- Role
- Role Term:
Text
- Reader
- Name:
Personal
- Name Part
- Fischer, Karen
- Role
- Role Term:
Text
- Reader
- Name:
Personal
- Name Part
- Evans, Alex
- Role
- Role Term:
Text
- Reader
- Name:
Personal
- Name Part
- Buffett, Bruce
- Role
- Role Term:
Text
- Reader
- Name:
Personal
- Name Part
- Hirth, Greg
- Role
- Role Term:
Text
- Reader
- Name:
Corporate
- Name Part
- Brown University. Department of Earth, Environmental, and Planetary Sciences
- Role
- Role Term:
Text
- sponsor
- Origin Information
- Copyright Date
- 2025
- Physical Description
- Extent
- xv, 145 p.
- digitalOrigin
- born digital
- Note:
thesis
- Thesis (Ph. D.)--Brown University, 2025
- Genre (aat)
- theses
- Abstract
- Earth's mantle governs the transfer of heat, the generation of the magnetic field, the cycling of key elements, and the style of tectonic deformation at the surface. Because mantle convection is the primary mechanism linking Earth's deep interior to the surface, changes in convective regime can reshape a planet's thermal, chemical, and tectonic evolution. This dissertation examines the physics and implications of transitions in mantle convection regimes, with emphasis on their underlying stability (Chapter 1), their role in sustaining a long-lived magnetic field (Chapter 2), and their coupling to the deep water cycle (Chapter 3).
Building on the semi-analytical framework of Crowley and O’Connell (2012), Chapter 1 constructs a regime diagram for multi-solution mantle convection and performs a bifurcation and linear stability analysis. I identify a new dimensionless parameter, analogous to a plate resistance number, that controls the emergence of multiple steady-state solutions and, along with the Rayleigh number, constructs the phase space where convection can switch between sluggish-lid and active-lid behavior.
Chapter 2 couples this convection framework with a model of core thermochemical evolution to explore the viability of a dynamo before inner core formation. I show that a sluggish-lid regime, where surface plates are mobile but partially decoupled from the mantle, allows sufficient core cooling to sustain a magnetic field throughout the Precambrian. This result bridges longstanding gaps between geologic constraints on mantle temperature and magnetic field persistence.
Chapter 3 introduces a coupled model for mantle water evolution and its feedbacks on convection. By tracking water cycling through melting, dehydration, regassing, and redistribution, I show that transitions in tectonic regime can arise from feedbacks among melt production, water retention, and asthenospheric viscosity. These transitions drive transient behavior in plate speeds, melt depth, and mantle cooling rates.
Taken together, this work highlights the dynamic role of the asthenosphere in planetary evolution and the importance of water in shaping Earth's interior and surface history. It also opens a framework for understanding the deep water cycle's influence on planetary habitability on Earth and beyond.
- Subject (fast)
(authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/00940406")
- Topic
- Geodynamics
- Subject (fast)
(authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/00917265")
- Topic
- Evolution
- Subject (fast)
(authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/01860481")
- Topic
- Earth (Planet)
- Subject
- Topic
- Earth
- Subject (fast)
(authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/01764670")
- Topic
- Lithosphere
- Subject
- Topic
- Asthenosphere
- Subject
- Topic
- planetary interiors
- Subject (fast)
(authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/00900729")
- Topic
- Earth sciences
- Subject
- Topic
- geodynamo
- Subject (fast)
(authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/00953797")
- Topic
- Heat--Convection, Natural
- Subject (fast)
(authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/00878940")
- Topic
- Core-mantle boundary
- Subject (fast)
(authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/01171689")
- Topic
- Water cycles
- Language
- Language Term (ISO639-2B)
- English
- Record Information
- Record Content Source (marcorg)
- RPB
- Record Creation Date
(encoding="iso8601")
- 20251201