pgleissner

Dr. Philipp Gleißner

Freie Universität Berlin - Geochemistry

Postdoc

Malteserstraße 74-100, Room B221, 12249 Berlin, Phone: +49-30-838-70904

 

Project B1: Origin of the depletion of volatile metals in lunar rocks

The mantle of the Moon has many compositional and isotopic similarities to the mantle of the Earth, but is believed to be considerably more depleted
in volatile elements than Earth’s mantle. Therefore, volatile loss (e.g., degassing) and delivery processes (e.g., late accretion) are keystones to our
understanding of the Earth-Moon system. However, the details of depletion and enrichment in lunar reservoirs are not understood, and the abundances
of some siderophile volatile elements such as S, Se, Te, Zn, Cd, In and Tl are quite variable in highland rocks and in mare basalts. Thus, to trace the
composition of material accreted on the Moon prior to 3.8 Ga, in our previous work on lunar impactites and some pristine highland samples (i.e.,

endogenous igneous rocks that have very little or no contamination with impactor material) we applied isotope dilution methods to obtain highly
siderophile element and siderophile volatile element abundance data (B1 2016-2019). In contrast to the highly siderophile elements, the budget of
most siderophile elements in lunar impactites appears to be predominantly controlled by target rock compositions and not by impactors. However,
assessing the role of different fractionation processes of the siderophile volatile elements has been a major challenge, because both lunar core formation
(e.g., metal-silicate or sulfide-silicate partitioning), degassing of lunar magmas and presumably the moon-forming event have affected abundances of these
elements in lunar rocks. To address these challenges, here we will investigate the coupled behavior of mass-dependent stable isotope variations of Zn, Cu,
K and S in various lunar lithologies. The isotopic and concentration data will be compared to complementary experimental volatilization studies in subproject B7.

 

Current work: Origin of fractionations of siderophile volatile elements in pristine lunar highland rocks and mare basalts

For lunar samples we still rely on older mass fraction data (mainly radiochemical neutron activation analysis), which have not been tested by isotope dilution
inductively coupled plasma mass spectrometry methods. Furthermore, some key elements like S and Cu were often not included in early studies of lunar rocks.
In the current project we determined new isotope dilution data for mass fractions of siderophile volatile elements in lunar highland rocks and mare basalts.

Figure 1

(Fig. 1) Petrographic characterization of a basalt subsample before analysis at Geochemistry Laboratory, Freie Universität Berlin.

In a chondrite normalized diagram low-Ti and high-Ti mare basalts display almost parallel patterns with variable depletions when compared to Cu (the least volatile
element in our study). The analyzed elements are characterized by variable metal-sulfide-silicate partition coefficients, ranging from 101 to 103 and the observed
distribution most likely reflects a combination of partition and volatility driven processes. Thus, the distribution of siderophile volatile elements in mare basalts can reveal
insights into fractionation processes which occurred during their formation, in the source regions of the magmas or even before the mantle sources were formed.

Figure 2

(Fig. 2) Results: Mass fractions of siderophile volatile elements in lunar mare basalts normalized to abundances in average CI chondrite. Elements are
displayed in the order of decreasing 50% condensation temperature form a gas of solar composition.

 
 
 
 
Publications

2020

Gleißner, P. and H. Becker, 2020: New constraints on the formation of lunar mafic melt breccias from S-Se-Te and highly siderophile elements. Meteoritics & Planetary Science, 55, Nr 9, 244-2065. 10.1111/maps.13557

2019

Gleißner, P., 2019: The Earth–Moon late-accretion conundrum. Nature Geoscience, Vol. 12, pp. 683–684. 10.1038/s41561-019-0445-0

Gleißner, P. and H. Becker, 2019: Origin of lunar fragmental matrix breccias - Highly siderophile element constraints. Meteoritics & Planetary Science, 54, Nr 9, 2006-2026. 10.1111/maps.13363

2017

Gleißner, P. and H. Becker, 2017: Formation of Apollo 16 impactites and the composition of late accreted material: constraints from Os isotopes, highly siderophile elements and sulfur abundances, 200, 1-24, Geochimica et Cosmochimica Acta. 10.1016/j.gca.2016.12.017

 
Conferences

Gleißner, P., Salme, J. and Becker, H. (2021): Magmatic fractionation and degassing of siderophile volatile elements in lunar magmatic rocks. 52nd Lunar and Planetary Science Conference

Gleißner, P. and Becker, H. (2019): Siderophile elements in lunar granulitic impactites – Constraints on pre 4 Ga late accretion. Paneth Kolloquium

Gleißner, P. and Becker, H. (2019): The composition of basin forming impactors and large-scale impact gardening in the lunar highlands. 50th Lunar and Planetary Science Conference

Gleißner, P. and Becker, H. (2018): Siderophile elements in lunar granulitic impactites: constraints on the composition of pre 4 Ga late accretion. American Geophysical Union, Fall Meeting

Gleißner, P. and Becker, H. (2018): The composition of lunar basin forming impactors: Constraints from siderophile elements in ancient impactites. 49th Lunar and Planetary Science Conference

Gleißner, P. and Becker, H. (2017): Origin of non-chondritic highly siderophile element patterns in lunar fragmental matrix breccia. Paneth Kolloquium

Gleißner, P. and Becker, H. (2017): Combining S-Se-Te and highly siderophile element abundances in ancient lunar impactites – New constraints on impactor composition, mixing and lunar differentiation. Interdisciplinary workshop "Accretion and Early Differentiation of the Earth and Terrestrial Planets"

Gleißner, P. and Becker, H. (2017): Late accreted material on the lunar surface: Constraints from highly siderophile and chalcophile elements in ancient lunar impactites. New Views of the Moon 2 — Europe

Gleißner, P. and Becker, H. (2017): Combining S-Se-Te and highly siderophile element abundances in ancient lunar impactites – New constraints on impactor composition, mixing and lunar differentiation. 48th Lunar and Planetary Science Conference

Gleißner, P. and Becker, H. (2016): Highly siderophile and chalcophile elements in lunar impact rocks; Constraints on the composition of late accreted material. 79th Annual Meeting of the Meteoritical Society

Gleißner, P. and Becker, H. (2016): Highly siderophile element fractionations in Apollo 16 impact melt rocks: Large-scale fractionation processes. 47th Lunar and Planetary Science Conference

Gleißner, P. and Becker, H. (2016): Highly siderophile element fractionations in Apollo 16 impact melt rocks: Effects of small-scale processes. 47th Lunar and Planetary Science Conference