| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
|
| Initial Amendment Date: | July 21, 2010 |
| Latest Amendment Date: | July 21, 2010 |
| Award Number: | 1019440 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Jennifer Wade
jwade@nsf.gov (703)292-4739 EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | August 1, 2010 |
| End Date: | July 31, 2015 (Estimated) |
| Total Intended Award Amount: | $350,001.00 |
| Total Awarded Amount to Date: | $350,001.00 |
| Funds Obligated to Date: |
|
| History of Investigator: |
|
| Recipient Sponsored Research Office: |
1109 GEDDES AVE STE 3300 ANN ARBOR MI US 48109-1015 (734)763-6438 |
| Sponsor Congressional District: |
|
| Primary Place of Performance: |
1109 GEDDES AVE STE 3300 ANN ARBOR MI US 48109-1015 |
| Primary Place of
Performance Congressional District: |
|
| Unique Entity Identifier (UEI): |
|
| Parent UEI: |
|
| NSF Program(s): | Petrology and Geochemistry |
| Primary Program Source: |
|
| Program Reference Code(s): |
|
| Program Element Code(s): |
|
| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
One of the fundamental questions for understanding volcanic and deep magmatic processes is how fast minerals grow or dissolve in a magma under a given condition. However, the seemingly simple question has only begun to be addressed recently. This award will allow the investigator to continue to undertake an experimental and theoretical modeling study of mineral dissolution and growth in silicate melts. Diffusive and convective crystal dissolution of plagioclase and quartz (two of the most major minerals) in magmas will be investigated in the next grant period. This study will provide predictive methods to calculate dissolution rates of specific minerals in silicate melts as a function of temperature, pressure and other conditions. Furthermore, the crystallization history of magma oceans during early evolution of Moon and Earth will be modeled.
Mineral dissolution and growth are a fundamental process in igneous petrogenesis. In a magma conduit, chamber or ocean, entrained crystals and xenoliths and newly crystallized minerals would sink or rise depending on their density relative to the melt. The relative motion induces convection. Upon descent or ascent, each mineral grain would undergo dissolution (if the ambient melt is undersaturated with respect to the mineral) or growth (if there is oversaturation) in the presence of convection. This study's ultimate aim is to provide a practical method for estimating convective mineral dissolution and growth rates. It is proposed to obtain the necessary data and develop relations to directly calculate diffusive and convective dissolution rates of two mafic minerals: olivine and clinopyroxene, in basaltic melts as a function of temperature, pressure, and melt composition. In this next grant period, the investigator and his team will investigate the dissolution kinetics of two felsic minerals: plagioclase in basaltic melts and quartz in felsic melts, including the relative role of interface reaction and mass transport in controlling the dissolution rates. Furthermore, with experimental data and theoretical understanding accumulated over the years, they will develop models for the crystallization history and evolution of lunar and terrestrial magma oceans. The new work will significantly improve our fundamental understanding of magmatic processes and magma ocean evolution.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
Note:
When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external
site maintained by the publisher. Some full text articles may not yet be available without a
charge during the embargo (administrative interval).
Some links on this page may take you to non-federal websites. Their policies may differ from
this site.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Igneous rocks are complicated multimineralic materials formed by the crystallization of magmas. The thermodynamics of magma crystallization has been systematically studied by experiments for about 100 years, so that given a melt composition it is now possible to roughly predict the crystallization sequence, the crystallization temperature of each mineral, as well as the proportion of the minerals at a given temperature assuming equilibrium. On the other hand, the kinetics of magma crystallization has not been investigated much, meaning that the rate of crystal growth and the size distribution of crystals in a rock cannot be predicted given initial composition and cooling history, or conversely, cooling history cannot be inferred from initial conditions and crystal size distributions of different minerals. For these goals to be reached, systematic experiments on mineral growth and dissolution kinetics are necessary. Our study supported by the last NSF grant was a part of the long-term systematic kinetic study. Because it is easier to conduct and treat controlled dissolution experiments than growth experiments, we have investigated the dissolution kinetics of two major minerals – plagioclase and quartz, and a trace but ubiquitous and important mineral – zircon. The experiments also provide diffusion data, essential for understanding mineral growth kinetics. Our previous studies of olivine growth and dissolution kinetics have been applied to quantify post-entrapment evolution of melt inclusions in olivine.
One difference between experiments and natural magmatic processes is that crystals sink or rise in a magma chamber, but experiments do not have the large space dimension for crystal motion and hence are typically controlled to be diffusive for accurate treatment. Crystal descent or ascent often leads to layering in a magmatic body. One example of such layering is the collection of sulfide liquid droplets in the lower part of a magma body, forming magmatic sulfide ore deposits. These deposits are critical resources for industry, accounting for about 60% of the world's Ni and 40% of the world's platinum-group elements. Theories for crystal or liquid drop growth rates during descent or ascent are available but need to be applied to natural processes by incorporating the growth kinetics and descent dynamics during cooling. We have developed a model to quantify sulfide droplet growth and settling in a magma chamber to understand the conditions for magmatic sulfide ore formation.
Our achievement under this grant also includes a theoretical contribution to treat diffusion in heterogeneous media. Examples of heterogeneous media include multimineralic rocks, single-mineral rocks with grain boundaries, soil, concrete, paint, textile, plant, etc. We found that previous treatment was erroneous, and discovered a simple way to correctly treat the problem. Although somewhat esoteric, this is one of our more lasting contributions to science.
The grant also supported our research on early Earth evolution, infrared measurement of H2O contents in apatite, and water in magmas and rocks. We have also had the opportunity to publish review articles to communicate our research to the broader scientific community.
Last Modified: 10/11/2015
Modified by: Youxue Zhang
Please report errors in award information by writing to: awardsearch@nsf.gov.
