A laser-ablation ICPMS study of Apollo 15 low-titanium olivine-normative and quartz-normative mare basalts
dc.contributor.author | Schnare, Darren W. | |
dc.contributor.author | Day, James M.D. | |
dc.contributor.author | Norman, Marc | |
dc.contributor.author | Yang, Liu | |
dc.contributor.author | Taylor, Lawrence A. | |
dc.date.accessioned | 2015-12-08T22:36:22Z | |
dc.date.issued | 2008 | |
dc.date.updated | 2015-12-08T09:49:48Z | |
dc.description.abstract | Apollo 15 low-Ti mare basalts have traditionally been subdivided into olivine- and quartz-normative basalt types, based on their different SiO2, FeO, and TiO2 whole-rock compositions. Previous studies have reconciled this compositional diversity by considering the olivine- and quartz-normative basalts as originating from different lunar mantle source regions. To provide new information on the compositions of Apollo 15 low-Ti mare basalt parental magmas, we report a study of major and trace-element compositions of whole rocks, pyroxenes, and other phases in the olivine-normative basalts 15016 and 15555 and quartz-normative basalts 15475 and 15499. Results show similar rare-earth-element patterns in pyroxenes from all four basalts. The estimated equilibrium parental-melt compositions from the trace-element compositions of pyroxenes are similar for 15016, 15555 and 15499. Additionally, an independent set of trace-element distribution coefficients has been determined from measured pyroxene and mesostasis compositions in sample 15499. These data suggest that fractional crystallization may be a viable alternative to compositional differences in the mantle source to explain the ∼25% difference in whole-rock TiO2, and corresponding differences in SiO2 and FeO between the Apollo 15 olivine- and quartz-normative basalts. In this model, the older (∼3.35 Ga) quartz-normative basalts, with lower TiO2 experienced olivine, chromite, and Cr-ulvöspinel fractionation at 'crustal levels' in magma chambers or dikes, followed by limited near-surface mineral fractionation, within the lava flows. In contrast, the younger (∼3.25 Ga) olivine-normative basalts experienced only limited magmatic differentiation at 'crustal-levels', but extensive near-surface mineral fractionation to produce their evolved mineral compositions. A two-stage mineral-fractionation model is consistent with textural and mineralogical observations, as well as the mineral trace-element constraints developed by this study. | |
dc.identifier.issn | 1872-9533 | |
dc.identifier.uri | http://hdl.handle.net/1885/35223 | |
dc.publisher | Pergamon-Elsevier Ltd | |
dc.source | Geochimica et Cosmochimica Acta | |
dc.subject | Keywords: chemical composition; fractional crystallization; igneous geochemistry; inductively coupled plasma method; isotopic fractionation; magma; magmatic differentiation; mantle source; mare basalt; olivine; pyroxene; quartz; rare earth element; trace element | |
dc.title | A laser-ablation ICPMS study of Apollo 15 low-titanium olivine-normative and quartz-normative mare basalts | |
dc.type | Journal article | |
local.bibliographicCitation.issue | 10 | |
local.bibliographicCitation.lastpage | 2572 | |
local.bibliographicCitation.startpage | 2556 | |
local.contributor.affiliation | Schnare, Darren W., University of Tennessee | |
local.contributor.affiliation | Day, James M.D., University of Tennessee | |
local.contributor.affiliation | Norman, Marc, College of Physical and Mathematical Sciences, ANU | |
local.contributor.affiliation | Yang, Liu, University of Tennessee | |
local.contributor.affiliation | Taylor, Lawrence A., University of Tennessee | |
local.contributor.authoremail | u4039549@anu.edu.au | |
local.contributor.authoruid | Norman, Marc, u4039549 | |
local.description.embargo | 2037-12-31 | |
local.description.notes | Imported from ARIES | |
local.identifier.absfor | 040203 - Isotope Geochemistry | |
local.identifier.absseo | 970104 - Expanding Knowledge in the Earth Sciences | |
local.identifier.ariespublication | u4027924xPUB122 | |
local.identifier.citationvolume | 72 | |
local.identifier.doi | 10.1016/j.gca.2008.02.021 | |
local.identifier.scopusID | 2-s2.0-43349099600 | |
local.identifier.thomsonID | 000256174500008 | |
local.identifier.uidSubmittedBy | u4027924 | |
local.type.status | Published Version |
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