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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Geophysical investigations of the Reykjanes Ridge and Kolbeinsey Ridge seafloor spreading centers

Appelgate, Bruce January 1995 (has links)
Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 77-86). / Microfiche. / ix, 86 leaves, bound ill. (some col.) 29 cm
32

Hydrothermally altered basalts from the Mariana Trough

Trembly, Jeffrey Allen January 1982 (has links)
No description available.
33

Magma chamber structure and Moho reflections along the East Pacific Rise /

Babcock, Jeffrey Matthew, January 1997 (has links)
Thesis (Ph. D.)--University of California, San Diego, 1997. / Vita. Includes bibliographical references.
34

Seafloor spreading processes in protoarc-forearc settings eastern Albanian ophiolite as a case study /

Phillips, Charity M.. January 2004 (has links)
Thesis (M.S.)--Miami University, Dept. of Geology, 2004. / Title from first page of PDF document. Includes bibliographical references (p. 126-129).
35

Mass transport processes and deposits in offshore Trinidad and Venezuela, and their role in continental margin development

Moscardelli, Lorena Gina, January 1900 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.
36

Experimental and seismological constraints on the rheology, evolution, and alteration of the lithosphere at oceanic spreading centers

DeMartin, Brian J., 1976- January 2007 (has links)
Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2007. / Includes bibliographical references (p. 194-197). / Oceanic spreading centers are sites of magmatic, tectonic, and hydrothermal processes. In this thesis I present experimental and seismological constraints on the evolution of these complex regions of focused crustal accretion and extension. Experimental results from drained, triaxial deformation experiments on partially molten olivine reveal that melt extraction rates are linearly dependent on effective mean stress when the effective mean stress is low and non-linearly dependent on effective mean stress when it is high. Microearthquakes recorded above an inferred magma reservoir along the TAG segment of the Mid-Atlantic Ridge delineate for the first time the arcuate, subsurface structure of a long-lived, active detachment fault. This fault penetrates the entire oceanic crust and forms the high-permeability pathway necessary to sustain long-lived, high-temperature hydrothermal venting in this region. Long-lived detachment faulting exhumes lower crustal and mantle rocks. Residual stresses generated by thermal expansion anisotropy and mismatch in the uplifting, cooling rock trigger grain boundary microfractures if stress intensities at the tips of naturally occurring flaws exceed a critical stress intensity factor. / (cont.) Experimental results coupled with geomechanical models indicate that pervasive grain boundary cracking occurs in mantle peridotite when it is uplifted to within 4 km of the seafloor. Whereas faults provide the high-permeability pathways necessary to sustain high-temperature fluid circulation, grain boundary cracks form the interconnected network required for pervasive alteration of the oceanic lithosphere. This thesis provides fundamental constraints on the rheology, evolution, and alteration of the lithosphere at oceanic spreading centers. / by Brian J. deMartin. / Ph.D.
37

Structure and evolution of an oceanic megamullion on the Mid-Atlantic ridge at 27N̊

McKnight, Amy R. (Amy Ruth), 1975- January 2001 (has links)
Thesis (S.M.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences and the Woods Hole Oceanographic Institution), 2001. / Includes bibliographical references (leaves 44-48). / Megamullions in slow-spreading oceanic crust are characterized by smooth "turtle-back" morphology and are interpreted to be rotated footwalls of long-lived detachment faults. Megamullions have been analyzed in preliminary studies, but many questions remain about structural and tectonic details of their formation, in particular how the hanging wall develops in conjugate crust on the opposing side of the rift axis. This study compares the structure of an off-axis megamullion complex and its conjugate hanging wall crust on the Mid-Atlantic Ridge near 27 0N. Two megamullion complexes, an older (Ml) and younger (M2), formed successively on the west side of the rift axis in approximately the same location within one spreading segment. Megamullion M1 formed while the spreading segment had only one inside comer on the west flank, and megamullion M2 formed after the segment developed double inside corners west of the axis and double outside corners east of the axis. The older megamullion formed between -22.3 and -20.4 Ma, and the younger megamullion formed between -20.6 and -18.3 Ma; they are presently -200-300 km off-axis. Reconstruction poles of plate rotation were derived and plate reconstructions were made for periods prior to initiation of the megamullion complex (anomaly 6Ar, -22.6 Ma), after the termination of megamullion Ml and during the development of megamullion M2 (anomaly 5E, -19 9 Ma), and shortly following the termination of megamullion M2 (anomaly 5C, -17.6 Ma). These reconstructions were used to compare morphological and geophysical features of both flanks at each stage of the megamullions' development. Megamullion Ml's breakaway occurred at -22.3 Ma and slip along this detachment fault continued and propagated northward at -20.6 Ma to form the northern portion of M2. The exhumed footwall of megamullion M1 has weak spreading-parallel lineations interpreted as mullion structures on its surface, and it forms an elevated plateau between the enclosing segment boundaries (non-transform discontinuities). There was an expansion southward of the detachment fault forming megamullion M2 at -20.1 Ma. It either cut a new detachment fault through megamullion Ml, stranding a piece of megamullion Ml on the conjugate side (east flank), or it linked into the active detachment fault that was forming megamullion M1 or propagated into its hanging wall. The expanded detachment of megamullion M2 and the termination of megamullion M1 occurred during a time when the enclosing spreading segment roughly doubled in length and formed two inside corners. Megamullion M2 developed prominent, high-amplitude (-600 m) mullion structures that parallel the spreading direction for more than 20 km at each inside corner. Its detachment fault was abandoned - 18.6 Ma in the south and ~18.3 Ma in the north ... / by Amy R. McKnight. / S.M.
38

Evolution of the oceanic lithosphere and shear wave travel time residuals from oceanic earthquakes

Duschenes, Jeremy David January 1976 (has links)
Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / Microfiche copy available in Archives and Science. / Bibliography: leaves 51-58. / by Jeremy D. Duschenes. / M.S.
39

The nature and origin of fine-scale sea-floor relief

Shih, John Shai-Fu January 1980 (has links)
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1980. / Microfiche copy available in Archives and Science. / Vita. / Bibliography : leaves 206-213. / by John Shai-Fu Shih. / Ph.D.
40

The crustal structure and subsidence history of aseismic ridges and mid-plate island chains

Detrick, Robert Sherman January 1978 (has links)
Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Science. / Microfiche copy available in Archives and Science. / Vita. / Includes bibliographies. / by Robert Sherman Detrick, Jr. / Ph.D.

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