Petrogenesis of picritic mare magmas: Constraints on the extent of early lunar differentiation

Details Petrogenesis of picritic mare magmas: Constraints on the extent of early lunar differentiation Petrogenesis of picritic mare magmas: Constraints on the extent of early lunar differentiation

Dec 2006

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006gecoa..70.5919l&link_type=abstract

Geochimica et Cosmochimica Acta, Volume 70, Issue 24, p. 5919-5934.

Computer Science

9

Scientific paper

Calculations of isobaric batch, polybaric batch, and polybaric fractional melting have been carried out on a variety of proposed lunar and terrestrial source region compositions. Results show that magmas with a generally tholeiitic character—plagioclase and high-Ca pyroxene crystallize before low-Ca pyroxene reflecting relatively high Al2O3 concentrations (>12 wt%)—are the inevitable consequence of anhydrous partial melting of source regions composed primarily of olivine and two pyroxenes with an aluminous phase on the solidus. Low-Al2O3 magmas (<10 wt%), as typified by the green picritic glasses in the lunar maria require deep (700 1000 km), low-Al2O3 source regions without an aluminous phase. The difference between primitive and depleted mantle beneath mid-ocean ridges amounts to less than 0.1 wt% Al2O3, whereas formation of the green glass source region requires a net loss of between 1.5 and 2.5 wt% Al2O3. Basalt extraction cannot account for fractionations of this magnitude. Accumulation of olivine and pyroxene at the base of a crystallizing magma ocean is, however, an effective method for producing the necessary Al2O3 depletions. Both olivine-rich and pyroxene-rich source regions can produce the picritic magmas, but mixing calculations show that both types of source region are likely to be hybrids consisting of an early- to intermediate-stage cumulate (olivine plus enstatite) and a later stage cumulate assemblage. Mass balance calculations show that refractory element-enriched bulk Moon compositions contain too much Al2O3 to allow for the deep low-Al2O3 source regions even after extraction of an Al2O3-rich (26 30 wt%) crust between 50 and 70 km thick.

Affiliated with

Also associated with

No associations

Rating

Petrogenesis of picritic mare magmas: Constraints on the extent of early lunar differentiation does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Petrogenesis of picritic mare magmas: Constraints on the extent of early lunar differentiation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Petrogenesis of picritic mare magmas: Constraints on the extent of early lunar differentiation will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1544005