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Mass Transfer and Chemical Interactions in Subduction Zones.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Mass Transfer and Chemical Interactions in Subduction Zones./
作者:	Codillo, Emmanuel Avila.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2023,
面頁冊數:	408 p.
附註:	Source: Dissertations Abstracts International, Volume: 85-02, Section: B.
Contained By:	Dissertations Abstracts International85-02B.
標題:	Plate tectonics. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30672253
ISBN:	9798380097048

Mass Transfer and Chemical Interactions in Subduction Zones.
Codillo, Emmanuel Avila.

Mass Transfer and Chemical Interactions in Subduction Zones. - Ann Arbor : ProQuest Dissertations & Theses, 2023 - 408 p.

Source: Dissertations Abstracts International, Volume: 85-02, Section: B.

Thesis (Ph.D.)--Massachusetts Institute of Technology, 2023.

Subduction zones are important sites of material recycling on Earth, with volatiles playing key roles in mass transfer processes and magma formation. This thesis investigates outstanding questions associated with a continuum of interrelated processes that occur as oceanic plates descend in subduction zones by integrating petrological and geochemical constraints from exhumed high-pressure rocks and erupted arc magmas, high pressure-temperature laboratory experiments, and thermodynamic calculations. Chapters 2 and 3 investigate the fluid-mediated reactions between mafic and ultramafic rocks at conditions relevant to the slab-mantle interface and show that Mg-metasomatism of mafic rocks to form chlorite-rich assemblages is favored and is likely more pervasive in subduction zones than in oceanic settings. Contrary to common belief, talc is unlikely to form in high abundance in ultramafic rocks metasomatized by Si-rich slab-derived fluids. This means that talc-rich assemblages formed via Si-metasomatism along the slab-mantle interface are less likely to be playing prominent roles in volatile transport, in facilitating slow-slip events, and in controlling the decoupling-coupling transition of the plate interface. Chapter 4 experimentally investigates the phase equilibria, melting, and density evolution of melange rocks that formed by mixing and fluid-rock interactions. Results show that melting of melanges is unlikely to occur along slab-tops at pressures ≤ 2.5 GPa. Accordingly, diapirism into the hotter mantle wedge would be required to initiate melting. The density contrast between melanges and the overlying mantle would allow for buoyancy-driven diapirism at relatively low pressures and melting could subsequently occur in the hotter mantle wedge during ascent. However, diapir buoyancy may be limited at higher pressures due to the formation of abundant garnet especially in melange rocks with peraluminous composition. Chapter 5 experimentally investigates the compositions of melts and mineral residues from melting of a mantle wedge hybridized with small amounts of melange rocks to simulate an end-member scenario where solid melange diapirs dynamically interact with the mantle wedge. Results from laboratory experiments show that melting of a melange-hybridized mantle wedge can produce melts that display compositional characteristics similar to arc magmas. Finally, Chapter 6 presents new interpretations on the evolution of slab-to-mantle transfer mechanisms from subduction initiation to arc maturity. Analyses of published magma compositions from global arcs reveal that melting of melange plays an increasingly important role in magma formation as slab-tops cool and arcs mature over time. This trend is attributed to the deepening of the decoupled plate interface during subduction where melange zones can form more extensively and contribute to the melting process more significantly. Taken together, this thesis highlights (i) the dynamic connection between mechanical mixing of different lithologies and fluid-rock interactions along the slab-mantle interface, (ii) how these processes modify the petrophysical and geochemical properties of subducted materials, and (iii) how these processes collectively influence the mechanisms of slab-to-mantle transfer, elemental cycles, and the formation of arc magmas worldwide.

ISBN: 9798380097048Subjects--Topical Terms:

542702
Plate tectonics.

Mass Transfer and Chemical Interactions in Subduction Zones.
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