En analysant finement la composition isotopique de la célèbre météorite martienne ALH84001, un groupe de chercheurs a trouvé des indices en faveur de l’existence d’une activité volcanique continuelle pendant au moins 4 milliards d’années depuis la naissance de la Planète rouge.
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Du volcanisme sur Mars pendant au moins 4 milliards d'années
Modérateurs : Eric, jerome, Travis, Charlotte, marie.m, Magda Dorner, Bull
Pour ceux que cela intéresse, l'abstract de Science :
Science. 2010 Apr 16;328(5976):347-51.
A younger age for ALH84001 and its geochemical link to shergottite sources in Mars.
Lapen TJ, Righter M, Brandon AD, Debaille V, Beard BL, Shafer JT, Peslier AH.
Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX 77204, USA. tjlapen@uh.edu
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.