title: A younger age for ALH84001 and its geochemical link to shergottite sources in Mars.
abstract: Martian meteorite ALH84001 (ALH) is the oldest known igneous rock from Mars and has been used to constrain its early history. Lutetium-hafnium (Lu-Hf) isotope data for ALH indicate an igneous age of 4.091 +/- 0.030 billion years, nearly coeval with an interval of heavy bombardment and cessation of the martian core dynamo and magnetic field. The calculated Lu/Hf and Sm/Nd (samarium/neodymium) ratios of the ALH parental magma source indicate that it must have undergone extensive igneous processing associated with the crystallization of a deep magma ocean. This same mantle source region also produced the shergottite magmas (dated 150 to 570 million years ago), possibly indicating uniform igneous processes in Mars for nearly 4 billion years.
authors.affiliation: Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX 77204, USA. tjlapen@uh.edu
authors.forename: T J
authors.initials: TJ
authors.lastname: Lapen
authors.forename: M
authors.initials: M
authors.lastname: Righter
authors.forename: A D
authors.initials: AD
authors.lastname: Brandon
authors.forename: V
authors.initials: V
authors.lastname: Debaille
authors.forename: B L
authors.initials: BL
authors.lastname: Beard
authors.forename: J T
authors.initials: JT
authors.lastname: Shafer
authors.forename: A H
authors.initials: AH
authors.lastname: Peslier