Trace-element partitioning between immiscible lunar melts: An example from naturally occurring lunar melt inclusions
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C.K. Shearer
,
J.J. Papike
Abstract
Evidence for liquid immiscibility on the Moon has been documented in melt inclusions in minerals that crystallized from mare basalts, within mesostasis in mare basalts and in at least one sample of a lunar plutonic rock. This study focuses on trace-element partitioning between immiscible melt pairs occurring as inclusions in plagioclase. These inclusions are blade-like in shape and range in length from 2 to 150 μm. They consist of two coexisting glasses separated by a sharp meniscus. The colorless, low-index glass (felsite) is spherical and immersed in a dark-brown, high-index glass (high-Fe basalt). The Fe-rich basaltic component of the inclusion is quartz + hypersthene normative with low Mg/(Mg + Fe) and variable SiO2 content (between 34 and 45 wt%). The felsic component has a SiO2 content between 72 and 82 wt% and variable K2O (4.4 to 8.5 wt%)
In most cases, the partitioning behavior of the trace elements agrees with behavior either predicted or measured in experimental and natural systems. The high charge density elements preferentially partition into the basaltic component. High P2O5 and a wider solvus increase the Dbasalt/felsite for these elements. In contrast to many experimental studies and in agreement with studies of natural silicate liquid immiscibility, the Dbasalt/felsite for Ba indicates a preference for the felsic component. This difference in Ba behavior between experimental and natural samples has been attributed to differences in melt polymerization and compensation for charge unbalance within the polymerized melt structure. The apparent differences in Dbasalt/felsite for Sr and divalent Eu between the Apollo 11 high-Ti basalts and Apollo 12 low-Ti basalts may be a result of either subtle differences in bulk composition or the extent of plagioclase plating on inclusion walls. Based on our partitioning data from melt inclusions and the chemical characteristics of lunar felsites, the latter cannot be a product of simple fractional crystallization. Silicate liquid immiscibility can account for fractionation of Ba/ La, K/U, and Ba/U in the lunar felsites and the limited variation in Zr/La. However, it cannot account for the REE pattern of the lunar felsites or the fractionation of U/La. These characteristics must be attributed to whitlockite crystallization prior to the onset of liquid immiscibility.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
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- Trace-element partitioning between immiscible lunar melts: An example from naturally occurring lunar melt inclusions
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- Assemblages with titanite (CaTiOSiO4), Ca-Mg-Fe olivine and pyroxenes, Fe-Mg-Ti oxides, and quartz: Part II. Application
- The stability of clinopyroxene in the system CaO-MgO-SiO2-TiO2 (CMST)
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- Al,Si order in the crystal structure of α-eucryptite (LiAlSiO4)
- TEM-EDX study of weathered layers on the surface of volcanic glass, bytownite, and hypersthene in volcanic ash from Sakurajima volcano, Japan
- Electron microscopic study of the dehydration of diaspore
- Crystal properties and energetics of synthetic kaolinite
- Structures and energies of AlOOH and FeOOH polymorphs from plane wave pseudopotential calculations
- XPS measurement of fivefold and sixfold coordinated sulfur in pyrrhotites and evidence for millerite and pyrrhotite surface species
- Structure of synthetic 6-line ferrihydrite by electron nanodiffraction
- Atomic structures of planar defects in oxybiotite
- Potassium hydrogen disilicate: A possible model compound for 17O NMR spectra of hydrous silicate glasses
- Strain analysis of phase transitions in (Ca,Sr)TiO3 perovskites
- Triclinic liddicoatite and elbaite in growth sectors of tourmaline from Madagascar
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Articles in the same Issue
- Partitioning of Sr between coexisting minerals of the hollandite- and piemontite-groups in a quartz-rich schist from the Sanbagawa metamorphic belt, Japan
- Crystallization processes in migmatites
- Amblygonite-montebrasite solid solutions as monitors of fluorine in evolved granitic and pegmatitic melts
- Reduction of water loss from gold-palladium capsules during piston-cylinder experiments by use of pyrophyllite powder
- Trace-element partitioning between immiscible lunar melts: An example from naturally occurring lunar melt inclusions
- Assemblages with titanite (CaTiOSiO4), Ca-Mg-Fe olivine and pyroxenes, Fe-Mg-Ti oxides, and quartz: Part I. Theory
- Assemblages with titanite (CaTiOSiO4), Ca-Mg-Fe olivine and pyroxenes, Fe-Mg-Ti oxides, and quartz: Part II. Application
- The stability of clinopyroxene in the system CaO-MgO-SiO2-TiO2 (CMST)
- Ordering kinetics of Mg-Fe2+ exchange in a Wo43En46Fs11 augite
- Al,Si order in the crystal structure of α-eucryptite (LiAlSiO4)
- TEM-EDX study of weathered layers on the surface of volcanic glass, bytownite, and hypersthene in volcanic ash from Sakurajima volcano, Japan
- Electron microscopic study of the dehydration of diaspore
- Crystal properties and energetics of synthetic kaolinite
- Structures and energies of AlOOH and FeOOH polymorphs from plane wave pseudopotential calculations
- XPS measurement of fivefold and sixfold coordinated sulfur in pyrrhotites and evidence for millerite and pyrrhotite surface species
- Structure of synthetic 6-line ferrihydrite by electron nanodiffraction
- Atomic structures of planar defects in oxybiotite
- Potassium hydrogen disilicate: A possible model compound for 17O NMR spectra of hydrous silicate glasses
- Strain analysis of phase transitions in (Ca,Sr)TiO3 perovskites
- Triclinic liddicoatite and elbaite in growth sectors of tourmaline from Madagascar
- Letter. A simple inorganic process for formation of carbonates, magnetite, and sulfides in martian meteorite ALH84001
