Show simple item record

dc.contributor.advisor Weeraratne, Dayanthie S en
dc.contributor.author Brand, Danielle en
dc.date.accessioned 2014-07-30T23:32:12Z en
dc.date.available 2014-07-30T23:32:12Z en
dc.date.copyright 2014 en
dc.date.issued 2014-07-30 en
dc.date.submitted 2014-05 en
dc.identifier.uri http://hdl.handle.net/10211.3/123509 en
dc.description Includes bibliographical references (pages 55-58) en
dc.description California State University, Northridge. Department of Geological Sciences. en
dc.description.abstract The gravitational settling dynamics of molten iron droplets through silicate material is an important process during the early impact history of the Earth where settling may have occurred within magma oceans or within metal plume conduits descending rapidly to form the metallic cores in terrestrial bodies. Implications for equilibration of liquid metal in the silicate mantle are key in aiding our understanding of the thermo-chemical evolution of Earth. To simultaneously meet geochemical constraints for rapid core formation as well as siderophile trace element distribution throughout the upper mantle, an emulsion of iron droplets or an emulsion metal plume may be important. Previous experiments have shown that descending metal silicate plumes entrain magma ocean material in trailing conduits that travel to the core-mantle boundary. It has also been shown that the style of metal emulsions will descend through these conduits in two stages, as a coalesced group within the plume head and later settling through the conduit column. However, the nature of iron settling through a magma ocean and within conduits is only understood in a rudimentary way. Here, I consider physical fluid models which study the settling of liquid iron droplets through silicate melts using liquid gallium emulsions and glucose solutions. I test the effect of several physical properties including the metal volumetric ratio, density difference, fluid viscosity, metal droplet diameter, and liquid versus solid metal spheres. Three stages are observed during gravitational settling. Regime 1 reveals rapid sinking of liquid metal droplets and entrainment of low-density (light element) fluids into a metal pond and into the core itself, regime 2 is characterized by upward migration of entrained fluid and regime 3 couples slow compaction of metal droplets at the base with final segregation of residual glucose solution. Results show that high volumetric ratios and low viscosity ratios of metal to magmas will have faster sinking velocities and metal pond or core formation times. I find that increased metal volumetric ratio and liquid (versus solid) metal spheres demonstrates more entrainment of magma into a metal pond or into the core. Higher levels of entrainment predicts the presence of light elements in the core during its formation and suggests “bottom-up” migration of light elements and metal-silicate segregation at high pressures during post core forming events. Upward migration of light elements will leave behind higher bulk density metals that initiate overturn in the outer core and can assist in powering the geodynamo. Finally, the settling process of emulsion metal droplets through magma oceans, plume conduits, and entrainment into the core provide a large surface areas and longer residence time for metal-silicate equilibration to address the excess siderophile observation while still descending rapidly enough to form the Earth's core in 30 My. I observe a metal sediment layer that forms above the metallic core after settling. If this sediment layer is stable, it may be entrained in upwelling mantle plumes over the Earth’s history and contribute towards mixing of siderophile elements with mantle minerals. en
dc.description.statementofresponsibility by Danielle Brand en
dc.format application/pdf en
dc.format.extent viii, 59 pages en
dc.language.iso en en
dc.publisher California State University, Northridge en
dc.rights.uri http://scholarworks.csun.edu/xmlui/handle/10211.2/286 en
dc.subject Core formation en
dc.subject Siderophile en
dc.subject Droplets en
dc.subject Settling en
dc.subject Conduit en
dc.subject Magma ocean en
dc.subject.other Dissertations, Academic -- CSUN -- Geology. en
dc.title Settling of metal droplets through a magma ocean and metal plume conduits during core formation en
dc.type Thesis en
dc.date.updated 2014-07-30T23:32:12Z en
dc.contributor.department Geological Sciences en
dc.description.degree M.S. en
dc.contributor.committeemember Simila, Gerald W en
dc.contributor.committeemember Tabidian, Mohamad A en
dc.rights.license By signing and submitting this license, you the author grant permission to CSUN Graduate Studies to submit your thesis or dissertation, and any additional associated files you provide, to CSUN ScholarWorks, the institutional repository of the California State University, Northridge, on your behalf. You grant to CSUN ScholarWorks the non-exclusive right to reproduce and/or distribute your submission worldwide in electronic or any medium for non-commercial, academic purposes. You agree that CSUN ScholarWorks may, without changing the content, translate the submission to any medium or format, as well as keep more than one copy, for the purposes of security, backup and preservation. You represent that the submission is your original work, and that you have the right to grant the rights contained in this license. You also represent that your submission does not, to the best of your knowledge, infringe upon anyone's copyright. If the submission contains material for which you do not hold copyright, or for which the intended use is not permitted, or which does not reasonably fall under the guidelines of fair use, you represent that you have obtained the unrestricted permission of the copyright owner to grant CSUN ScholarWorks the rights required by this license, and that such third-party owned material is clearly identified and acknowledged within the text or content of the submission. If the submission is based upon work that has been sponsored or supported by an agency or organization other than the California State University, Northridge, you represent that you have fulfilled any right of review or other obligations required by such contract or agreement. CSUN ScholarWorks will clearly identify your name(s) as the author(s) or owner(s) of the submission, and will not make any alterations, other than those allowed by this license, to your submission. en


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record

Search DSpace


My Account

RSS Feeds