Highly siderophile element depletion in the Moon
James M D Day1, Richard J Walker2
1Geosciences Research Division, Scripps Institution of Oceanography, La Jolla, CA 92093-0244, USA.
Earth and Planetary Science Letters
|September 1, 2021
Summary
This study analyzed highly siderophile element (HSE) and Os isotope data in lunar mare basalts. Results indicate a homogeneous lunar interior with low HSE abundances, consistent with late accretion before crust formation.
Area of Science:
- Geochemistry
- Isotope Geochemistry
- Planetary Science
Background:
- Lunar mare basalts provide insights into the Moon's mantle composition and evolution.
- Highly siderophile elements (HSEs) are crucial tracers of planetary formation and differentiation processes.
- Osmium (Os) isotopes offer a sensitive tool for tracking mantle evolution and accretion history.
Purpose of the Study:
- To determine the abundance and isotopic composition of HSEs in various lunar mare basalts.
- To constrain the origin and evolution of the lunar mantle.
- To investigate the nature and timing of late accretion on the Moon.
Main Methods:
- Analysis of coupled 187Os/188Os and HSE abundance data.
- Samples include Apollo mare basalts (12, 15, 17) and lunar meteorites (LAP 04841, MIL 05035).
- Modeling of partial melting and fractional crystallization processes.
Main Results:
- Most magnesian samples show chondrite-relative HSE abundances and chondritic initial 187Os/188Os.
- Mare basalts exhibit consistently low HSE abundances (~2x10^-5 to 2x10^-7 chondritic abundance).
- Apollo 12 basalts yield a Re-Os age of 3.0 ±0.6 Ga with an initial 187Os/188Os of 0.109 ±0.008.
Conclusions:
- Lunar mare basalt compositions suggest partial melting of metal-free sources with low HSE concentrations.
- Homogeneous HSE abundances across different lunar sites indicate a well-mixed lunar interior.
- Low HSE abundances and chondritic Re/Os ratios support ~0.02% late accretion prior to lunar crust formation.
Related Concept Videos
01:27Gravity between Spherical Bodies
8.8K
Newton's law of gravitation describes the gravitational force between any two point masses. However, for extended spherical objects like the Earth, the Moon, and other planets, the law holds with an assumption that masses of spherical objects are concentrated at their respective centers.
This assumption can be proved easily by showing that the expression for gravitational potential energy between a hollow sphere of mass (M) and a point mass (m) is the same as it would be for a pair of extended...
This assumption can be proved easily by showing that the expression for gravitational potential energy between a hollow sphere of mass (M) and a point mass (m) is the same as it would be for a pair of extended...
8.8K
03:45Formation of Complex Ions
24.5K
A type of Lewis acid-base chemistry involves the formation of a complex ion (or a coordination complex) comprising a central atom, typically a transition metal cation, surrounded by ions or molecules called ligands. These ligands can be neutral molecules like H2O or NH3, or ions such as CN− or OH−. Often, the ligands act as Lewis bases, donating a pair of electrons to the central atom. These types of Lewis acid-base reactions are examples of a broad subdiscipline called coordination...
24.5K
01:16Gravitation
7.4K
In the years before Newton, a general belief prevailed that different laws governed objects in the sky than objects on Earth. When Kepler wrote down the three laws of planetary motion, explaining in detail the geometrical properties of the planetary orbits around the Sun, there was no immediate idea to discern their connection with more fundamental laws. It was Isaac Newton who, in 1665–66, figured out the connection between planetary motion, the motion of the moon around the Earth, and...
7.4K
01:06Tidal Forces
2.8K
The origin of Earth's ocean tides has been a subject of continuous investigation for over 2000 years. However, the work of Newton is considered to be the beginning of the proper understanding of the phenomenon. Ocean tides are the result of gravitational tidal forces. These same tidal forces are present in any astronomical body; they are responsible for the internal heat that creates the volcanic activity on Io, one of Jupiter's moons, and the breakup of stars that get too close to...
2.8K
00:57The Periodic Table and Organismal Elements
192.0K
Overview
192.0K
01:29Biosynthesis of Lipids
194
Microbial membranes exhibit remarkable diversity in lipid composition, reflecting evolutionary adaptations to various environmental conditions. The three domains of life—Bacteria, Archaea, and Eukarya—synthesize membrane lipids through distinct biosynthetic pathways, leading to fundamental structural differences that impact membrane stability, function, and adaptability.Fatty Acid-Based Lipids in Bacteria and EukaryaBacteria and eukaryotes share a common fatty acid biosynthesis...
194