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Dynamics of Flat Slab Subduction ben...

Eakin, Caroline Mary.

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Dynamics of Flat Slab Subduction beneath Peru.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Dynamics of Flat Slab Subduction beneath Peru./
作者:	Eakin, Caroline Mary.
面頁冊數:	253 p.
附註:	Source: Dissertation Abstracts International, Volume: 76-11(E), Section: B.
Contained By:	Dissertation Abstracts International76-11B(E).
標題:	Geophysics. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3663526
ISBN:	9781321941241

Dynamics of Flat Slab Subduction beneath Peru.
Eakin, Caroline Mary.

Dynamics of Flat Slab Subduction beneath Peru. - 253 p.

Source: Dissertation Abstracts International, Volume: 76-11(E), Section: B.

Thesis (Ph.D.)--Yale University, 2015.

Many aspects of plate tectonics, the fundamental expression of the dynamic Earth, and the processes that have shaped the interior and surface of the planet we live on, remain to be fully understood. One aspect in which our knowledge is particularly lacking is that of flat subduction zones, which have often been linked to anomalous seafloor features with thickened, and therefore buoyant, oceanic crust. Flat subduction zones also have a potentially important impact upon the earth's surface, due to increased coupling between the subducting and overriding plates. Examples of these impacts include widespread uplift and deformation, increased seismic energy release, and heightened ore deposit formation.

ISBN: 9781321941241Subjects--Topical Terms:

535228
Geophysics.

Dynamics of Flat Slab Subduction beneath Peru.
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245 1 0 $a Dynamics of Flat Slab Subduction beneath Peru.
300 $a 253 p.
500 $a Source: Dissertation Abstracts International, Volume: 76-11(E), Section: B.
500 $a Adviser: Maureen D. Long.
502 $a Thesis (Ph.D.)--Yale University, 2015.
520 $a Many aspects of plate tectonics, the fundamental expression of the dynamic Earth, and the processes that have shaped the interior and surface of the planet we live on, remain to be fully understood. One aspect in which our knowledge is particularly lacking is that of flat subduction zones, which have often been linked to anomalous seafloor features with thickened, and therefore buoyant, oceanic crust. Flat subduction zones also have a potentially important impact upon the earth's surface, due to increased coupling between the subducting and overriding plates. Examples of these impacts include widespread uplift and deformation, increased seismic energy release, and heightened ore deposit formation.
520 $a In this work I study the dynamics of the Peruvian flat slab and the subducting Nazca Ridge, and how they affect deformation both at the surface and in the deep upper mantle, using geodynamical modeling and observations of seismic anisotropy. In chapter one I consider the history and development of flat subduction beneath Peru and its effect on uplift, flexure and dynamic topography at the surface above. I show that flat slabs are associated with a pulse of dynamic subsidence that propagates with the subduction leading edge. This long wavelength dynamic subsidence can explain widespread sedimentary deposits in western Amazonia both in space and time. Overall the change in subduction style beneath Peru during the Miocene appears to be closely linked to the evolution of the modern day Amazon River and drainage basin.
520 $a In chapter two, I report on the conduct of a detailed shear wave splitting analysis of a long running seismic station above the Peruvian flat slab. I find that the results vary with the incoming polarization of the shear wave and its frequency content, which can both be explained by multiple layers of anisotropy beneath the station. Modeling of the results returns a lower layer with fast directions that are generally trench normal. Further constraints from source-side splitting techniques indicate that this lower layer is likely to be generated by trench normal mantle flow beneath the flat slab.
520 $a In chapter three, I characterize seismic anisotropy above the Peruvian flat slab via splitting on local S phases. These reveal that the thin mantle layer that connects the flat slab to the continental crust above is seismically anisotropic and the pattern of deformation within it is strongly influenced by the southwards migration of the Nazca Ridge over time.
520 $a Following the isolation and description of anisotropy and mantle deformation above and below the flat slab in chapters two and three, I study shear wave splitting on SKS phases, which provide a vertically averaged signal through the whole subduction zone, in chapter four. These phases are recorded by an array of 49 seismic stations across southern Peru and provide the best illumination of spatial variability in the regional anisotropic structure. I find a sharp transition in seismic anisotropy across the northern edge of the subducting Nazca Ridge, with a previously unobserved and intriguing region of predominantly null splitting in the south. The buoyant Nazca Ridge therefore appears to play a key role in the mantle dynamics of the Peru flat slab system, as evidenced by the seismic anisotropy.
520 $a Lastly in chapter five, I present observations of splitting on deep local S and source-side phases that seem to directly constrain anisotropy within the steeply dipping section of the subducting Nazca slab. The fast directions found appear to correlate well with slab contours and therefore are most likely influenced by the slab morphology. Modeling of the geometry of anisotropy frozen-in at the paleo-spreading ridge and preserved within the oceanic lithosphere, does not provide a satisfactory explanation of the results. This leaves the conclusion that seismic anisotropy within the Nazca slab must be modified by subduction processes.
590 $a School code: 0265.
650 4 $a Geophysics. $3 535228
650 4 $a Plate tectonics. $3 542702
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773 0 $t Dissertation Abstracts International $g 76-11B(E).
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791 $a Ph.D.
792 $a 2015
793 $a English
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