Title Information
Title
BUILDING THE CONTINENTAL LITHOSPHERE: THE HISTORY OF THE CONTIGUOUS U.S. AS PRESERVED IN CRUST AND LITHOSPHERIC MANTLE STRUCTURES
Name: Personal
Name Part
Hopper, Emily
Role
Role Term: Text
creator
Origin Information
Copyright Date
2016
Physical Description
Extent
xx, 235 p.
digitalOrigin
born digital
Note
Thesis (Ph.D. -- Brown University (2016)
Name: Personal
Name Part
Fischer, Karen
Role
Role Term: Text
Director
Name: Personal
Name Part
Forsyth, Donald
Role
Role Term: Text
Reader
Name: Personal
Name Part
Hirth, Greg
Role
Role Term: Text
Reader
Name: Personal
Name Part
Parman, Stephen
Role
Role Term: Text
Reader
Name: Personal
Name Part
Wagner, Lara
Role
Role Term: Text
Reader
Name: Corporate
Name Part
Brown University. Geological Sciences
Role
Role Term: Text
sponsor
Genre (aat)
theses
Abstract
The lithosphere, the plate in ‘plate tectonics’, preserves a record of past and present tectonic processes in its internal structures and its boundary with the underlying asthenosphere. This dissertation uses scattered waves, largely common conversion point stacked Sp converted waves locally supplemented with a more formal wavefield migration, to image such structures in the crust and lithospheric mantle of the contiguous U.S. In the tectonically youngest western U.S. (Chapter 1), a shallow, sharp velocity gradient at the base of the lithosphere suggests a boundary defined by ponded melt. The lithosphere thickens with age of volcanism, implying the lithosphere is a melt-mitigated, conductively cooling thermal boundary layer. Beneath older, colder lithosphere where melt fractions are much lower, the velocity gradient at the base of such a layer should be a diffuse, purely thermal boundary. This is consistent with observations in the eastern U.S. (Chapter 2), where the boundary is locally sharp in areas of inferred enhanced upwelling only; and in the cratonic interior (Chapter 5), where the boundary is transparent to Sp waves. However, observations from the eastern U.S. indicate further complexity. Variations in current lithospheric thickness linked to Proterozoic rift boundaries suggest tectonic inheritance is significant at a lithospheric scale (Chapter 2). The preservation of relict tectonic structures like this gives insight into mechanisms of ancient deformation, with observations presented here emphasizing the importance of lateral accretion. A crustal suture in the southeastern U.S. generated by the final collision in the formation of the Appalachians is observed as a long, low-angle, dipping structure, accommodating several hundred kilometers of shortening (Chapter 3). The geometry of this feature is confirmed using an independent dataset and a wavefield migration technique that more accurately retrieves dips (Chapter 4). Ancient lateral accretion within the lithospheric mantle is preserved as dipping structures associated with relict subducted slabs from Paleoproterozoic continental accretion (Chapter 5). These observations suggest that lateral accretion is integral to the cratonic root formation process.
Subject
Topic
Receiver functions
Subject
Topic
Wavefield migration
Subject
Topic
Asthenosphere
Subject (FAST) (authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/1111306")
Topic
Seismology
Subject (FAST) (authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/1764670")
Topic
Lithosphere
Subject (FAST) (authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/1242475")
Geographic
North America
Record Information
Record Content Source (marcorg)
RPB
Record Creation Date (encoding="iso8601")
20160629
Language
Language Term: Code (ISO639-2B)
eng
Language Term: Text
English
Identifier: DOI
10.7301/Z0DJ5D22
Access Condition: rights statement (href="http://rightsstatements.org/vocab/InC/1.0/")
In Copyright
Access Condition: restriction on access
Collection is open for research.
Type of Resource (primo)
dissertations