Planetary science: Origins of one of the oldest martian meteorites identified

The origins of one of the oldest martian meteorites to be found on Earth, which contains the oldest martian igneous material that has been dated so far, are described in a paper published in Nature Communications this week.

Clues to the formation of Earth may be obtained from other terrestrial planets, such as Mars. However, so far the only available samples that appear to have recorded the early conditions on Mars are the meteorite Northwest Africa (NWA) 7034 and its paired stones. This meteorite contains the oldest martian igneous material dated so far (at approximately 4.5 billion years old). However, the original source of this meteorite is unknown.

Using the size and spatial distribution of more than 90 million impact craters detected using the Crater Detection Algorithm, Anthony Lagain and colleagues sought to identify the most likely ejection site from Mars for this material. The authors found that the oldest fragments of NWA 7034 were excavated approximately 1.5 billion years ago from an impact that formed the Khujirt crater — a 40km crater, from the north east of the Terra Cimmeria-Sirenum province, in the southern hemisphere of Mars. The ejected material from this impact were then subsequently ejected from Mars by a second impact, which formed the Karratha crater, 5–10 million years ago.

The authors suggest that this region of Mars constitutes a unique record of the first tens of millions of years of the history of Mars and should be a target for orbital analyses and exploration in the future.