The evolution of lithospheric deformation and crustal structure from continental margins to oceanic spreading centers
LocationU.S. East Coast Margin
This thesis investigates the evolution of lithospheric deformation and crustal structure from continental margins to mid-ocean ridges. The first part (Ch. 2) examines the style of segmentation along the U.S. East Coast Margin and investigates the relationship between incipient margin structure and segmentation at the modem Mid-Atlantic Ridge. The second part (Chs. 3-5) focuses on the mechanics of faulting in extending lithosphere. In Ch. 3, I show that the incorporation of a strain-rate softening rheology in continuum models results in localized zones of high strain rate that are not imposed a priori and develop in response to the rheology and boundar conditions. I then use this approach to quantify the effects of thermal state, crustal thickness, and crustal rheology on the predicted style of extension deformation. The mechanics of fault initiation and propagation along mid-ocean ridge segments is investigated in Ch. 4. Two modes of fault development are identified: Mode C faults that initiate near the center of a segment and Mode E faults that initiate at the segment ends. Numerical results from Ch. 5 predict that over time scales longer than a typical earhquake cycle transform faults behave as zones of significant weakness. Furthermore, these models indicate that Mode E faults formed at the inside-comer of a ridge-transform intersection wil experience preferential growth relative to faults formed at the conjugate outside-comer due to their proximity to the weak transform zone. Finally, the last par of this thesis (Ch. 6) presents a new method to quantify the relationship between the seismic velocity and composition of igneous rocks. A direct relationship is derived to relate V p to major element composition and typical velocity-depth profiles are used to calculate compositional bounds for the lower continental, margin, and oceanic crust.
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2002
Showing items related by title, author, creator and subject.
Zhu, Wenlu; Walsh, Joseph B. (2006-03-20)Rock is porous, with a connected network of cracks and pores. The static and dynamic behaviors of a rock sample under load depend on both the solid mineral matrix and the porous phase. In general, the configuration of the ...
Evolution of a Holocene delta driven by episodic sediment delivery and coseismic deformation, Puget Sound, Washington, USA Barnhardt, Walter A.; Sherrod, Brian L. (Blackwell, 2006-08-16)Episodic, large-volume pulses of volcaniclastic sediment and coseismic subsidence of the coast have influenced the development of a late Holocene delta at southern Puget Sound. Multibeam bathymetry, ground-penetrating radar ...
Glaciotectonic deformation associated with the Orient Point–Fishers Island moraine, westernmost Block Island Sound : further evidence of readvance of the Laurentide ice sheet Poppe, Lawrence J.; Oldale, Robert N.; Foster, David S.; Smith, Shepard M. (Springer, 2012-06-29)High-resolution seismic-reflection profiles collected across pro-glacial outwash deposits adjacent to the circa 18 ka b.p. Orient Point–Fishers Island end moraine segment in westernmost Block Island Sound reveal extensive ...