Dissertations / Theses on the topic 'Sea-floor spreading'
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Bullock, Andrew David. "From continental thinning to sea-floor spreading :." Thesis, University of Southampton, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403883.
Full textBaines, A. Graham. "Geodynamic investigation of ultra-slow spreading oceanic lithosphere Atlantis Bank and vicinity, SW Indian Ridge /." Laramie, Wyo. : University of Wyoming, 2006. http://proquest.umi.com/pqdweb?did=1188873761&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
Full textWhittaker, Joanne. "Tectonic consequences of mid-ocean ridge evolution and subduction." Thesis, The University of Sydney, 2008. http://hdl.handle.net/2123/3971.
Full textWhittaker, Joanne. "Tectonic consequences of mid-ocean ridge evolution and subduction." University of Sydney, 2008. http://hdl.handle.net/2123/3971.
Full textMid-ocean ridges are a fundamental but insufficiently understood component of the global plate tectonic system. Mid-ocean ridges control the landscape of the Earth's ocean basins through seafloor spreading and influence the evolution of overriding plate margins during midocean ridge subduction. The majority of new crust created at the surface of the Earth is formed at mid-ocean ridges and the accretion process strongly influences the morphology of the seafloor, which interacts with ocean currents and mixing to influence ocean circulation and regional and global climate. Seafloor spreading rates are well known to influence oceanic basement topography. However, I show that parameters such as mantle conditions and spreading obliquity also play significant roles in modulating seafloor topography. I find that high mantle temperatures are associated with smooth oceanic basement, while cold and/or depleted mantle is associated with rough basement topography. In addition spreading obliquities greater than > 45° lead to extreme seafloor roughness. These results provide a predictive framework for reconstructing the seafloor of ancient oceans, a fundamental input required for modelling ocean-mixing in palaeoclimate studies. The importance of being able to accurately predict the morphology of vanished ocean floor is demonstrated by a regional analysis of the Adare Trough, which shows through an analysis of seismic stratigraphy how a relatively rough bathymetric feature can strongly influence the flow of ocean bottom currents. As well as seafloor, mid-ocean ridges influence the composition and morphology of overriding plate margins as they are consumed by subduction, with implications for landscape and natural resources development. Mid-ocean ridge subduction also effects the morphology and composition of the overriding plate margin by influencing the tectonic regime experienced by the overriding plate margin and impacting on the volume, composition and timing of arc-volcanism. Investigation of the Wharton Ridge slab window that formed beneath Sundaland between 70 Ma and 43 Ma reveals that although the relative motion of an overriding plate margin is the dominant force effecting tectonic regime on the overriding plate margin, this can be overridden by extension caused by the underlying slab window. Mid-ocean ridge subduction can also affect the balance of global plate motions. A longstanding controversy in global tectonics concerns the ultimate driving forces that cause periodic plate reorganisations. I find strong evidence supporting the hypothesis that the plates themselves drive instabilities in the plate-mantle system rather than major mantle overturns being the driving mechanism. I find that rapid sub-parallel subduction of the Izanagi mid-ocean ridge and subsequent catastrophic slab break o_ likely precipitated a global plate reorganisation event that formed the Emperor-Hawaii bend, and the change in relative plate motion between Australia and Antarctica at approximately 50 Ma
Russell, Simon Mark. "A magnetic study of the west Iberia and conjugate rifted continental margins : constraints on rift-to-/drift processes." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4358/.
Full textSchwartz, Joshua J. "Growth and deformation of oceanic lithosphere Case studies from Atlantis Bank, Southwest Indian Ridge, and the Baker terrane, northeastern Oregon /." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1400957191&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
Full textKönig, Matthias. "Processing of shipborne magnetometer data and revision of the timing and geometry of the Mesozoic break-up of Gondwana = Auswertung schiffsfester Magnetometerdaten und die Neubestimmung des Zeitpunktes und der Geometrie des Mesozoischen Aufbruchs von Gondwana /." Bremerhaven : Alfred-Wegener-Inst. für Polar- und Meeresforschung, 2006. http://www.loc.gov/catdir/toc/fy0704/2006499118.html.
Full textMihut, Dona. "Breakup and mesozoic seafloor spreading between the Australian and Indian plates." Phd thesis, Department of Geology and Geophysics, 1997. http://hdl.handle.net/2123/8940.
Full textVan, Avendonk Hermanus Josephus Antonius. "An investigation of the crustal structure of the Clipperton transform fault area using 3D seismic tomography /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1998. http://wwwlib.umi.com/cr/ucsd/fullcit?p9823314.
Full textGrimes, Craig B. "Duration, rates, and patterns of crustal growth at slow-spreading mid-ocean ridges using zircon to investigate the evolution of in situ ocean crust /." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1799840381&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
Full textGreenhalgh, Erica. "A geodynamic model for continental breakup and sea-floor spreading initiation : implications for post-breakup rifted margin hinterland uplift." Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539517.
Full textDrumm, Stephanie Michelle. "Geochemical Modeling of Primary MORB Magmas: Implications for Parental Melting Regimes in Melt Lenses Along-Axis of the Hess Deep Rift." Scholar Commons, 2018. http://scholarcommons.usf.edu/etd/7147.
Full textBabcock, Jeffrey Matthew. "Magma chamber structure and Moho reflections along the East Pacific Rise /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1997. http://wwwlib.umi.com/cr/ucsd/fullcit?p9737307.
Full textDeMartin, Brian J. 1976. "Experimental and seismological constraints on the rheology, evolution, and alteration of the lithosphere at oceanic spreading centers." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/39010.
Full textIncludes 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.
Phillips, Charity M. "Seafloor Spreading Processes in Protoarc-Forearc Settings: Eastern Albanian Ophiolite as a Case Study." Oxford, Ohio : Miami University, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1083687853.
Full textMcKnight, Amy R. (Amy Ruth) 1975. "Structure and evolution of an oceanic megamullion on the Mid-Atlantic ridge at 27N̊." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/59090.
Full textIncludes 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.
Becker, Nathan C. "Recent volcanic and tectonic evolution of the Southern Mariana arc." Thesis, 2005. http://proquest.umi.com/pqdweb?index=1&did=982818821&SrchMode=2&sid=2&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1234310098&clientId=23440.
Full textAppelgate, Bruce. "Geophysical investigations of the Reykjanes Ridge and Kolbeinsey Ridge seafloor spreading centers." Thesis, 1995. http://hdl.handle.net/10125/9867.
Full textSheaffer, Steven D. "Oceanic transform boundaries rheology, dynamics, and the age offset limit /." 1995. http://catalog.hathitrust.org/api/volumes/oclc/40325520.html.
Full textMitchley, Michael. "An investigation into the detection of seafloor massive sulphides through sonar." Thesis, 2012. http://hdl.handle.net/10539/11337.
Full textSea oor massive sulphides are deep sea mineral deposits currently being examined as a potential mining resource. Locating these deposits, which occur at depths in the order of 2km, is currently performed by expensive submersible sonar platforms as conventional sonar bathymetry products gathered by sea surface platforms do not achieve adequate spatial resolution. This document examines the use of so-called high resolution beamforming methods (such as MUSIC and ESPRIT) for sonar bathymetry, together with combinations of parameter estimation techniques, including techniques for full rank covariance matrix estimation and signal enumeration. These methods are tested for bathymetric pro le accuracy using simulated data, and compared to conventional bathymetric methods. It was found that high resolution methods achieved greater bathymetric accuracy and higher resolution than conventional beamforming. These methods were also robust in the presence of unwanted persistent signals and low signal to noise ratios.
Russell, Joshua Berryman. "Structure and Evolution of the Oceanic Lithosphere-Asthenosphere System from High-Resolution Surface-Wave Imaging." Thesis, 2021. https://doi.org/10.7916/d8-33w6-f908.
Full textMoscardelli, Lorena Gina. "Mass transport processes and deposits in offshore Trinidad and Venezuela, and their role in continental margin development." Thesis, 2007. http://hdl.handle.net/2152/3080.
Full textMoscardelli, Lorena Gina 1977. "Mass transport processes and deposits in offshore Trinidad and Venezuela, and their role in continental margin development." 2007. http://hdl.handle.net/2152/13267.
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