Kinetic processes of mantle minerals
type: CreativeWork
description: This dissertation discusses the experimental results designed to constrain the processes of MORB generation. The main focus of this study is to investigate the location and the related processes of the transformation boundary from spinel to garnet peridotite facies at subsolidus conditions, because the presence of garnet in melting residues has significant influence to the conclusion drawn from geochemical/geophysical observations. Using an approach that monitors the rate of reaction progresses, the experimental results confirmed the presence of a region that garnet and spinel coexist in peridotite compositions. The trace element distribution among the product phases (opx and cpx) subsequent to the garnet breakdown reaction is in disequilibrium, due to the differences of diffusivity between major and trace elements. The presence of disequilibrium distribution in nature may be used to infer time scales of geodynamic processes. Diffusion coefficients of A1 in diopside are experimentally determined, and used for modeling the equilibration of major elements in pyroxene during MORB genesis. In summary, this dissertation contributes two major inferences: the location of the transformation boundaries of the gamet-spinel peridotite; the presence of disequilibrium trace elements distribution with equilibrium major elements distribution in mantle pyroxenes.
abstract: This dissertation discusses the experimental results designed to constrain the processes of MORB generation. The main focus of this study is to investigate the location and the related processes of the transformation boundary from spinel to garnet peridotite facies at subsolidus conditions, because the presence of garnet in melting residues has significant influence to the conclusion drawn from geochemical/geophysical observations. Using an approach that monitors the rate of reaction progresses, the experimental results confirmed the presence of a region that garnet and spinel coexist in peridotite compositions. The trace element distribution among the product phases (opx and cpx) subsequent to the garnet breakdown reaction is in disequilibrium, due to the differences of diffusivity between major and trace elements. The presence of disequilibrium distribution in nature may be used to infer time scales of geodynamic processes. Diffusion coefficients of A1 in diopside are experimentally determined, and used for modeling the equilibration of major elements in pyroxene during MORB genesis. In summary, this dissertation contributes two major inferences: the location of the transformation boundaries of the gamet-spinel peridotite; the presence of disequilibrium trace elements distribution with equilibrium major elements distribution in mantle pyroxenes.
author: Koga, Kenneth T.
language: en_US
keywords: Pyroxene, Peridotite
date published: 1999-09
date modified: 2026-07-27T22:05:21Z
provider: Woods Hole Oceanographic Institute
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Massachusetts Institute of Technology and Woods Hole Oceanographic Institution

PropertyValue
property ID: Handle
value: https://hdl.handle.net/1912/4106

PropertyValue
property ID: DOI
value: 10.1575/1912/4106