Nakhlites are a group of

Martian meteorite A Martian meteorite is a rock that formed on Mars, was ejected from the planet by an impact event, and traversed interplanetary space before landing on Earth as a meteorite. , 277 meteorites had been classified as Martian, less than half a percen ...

s, named after the first one,

Nakhla meteorite Nakhla is a Martian meteorite which fell in Egypt in 1911. It was the first meteorite reported from Egypt, the first one to suggest signs of aqueous processes on Mars, and the prototype for Nakhlite type of meteorites. History The Nakhla mete ...

. Nakhlites are

igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma o ...

s that are rich in

augite Augite is a common rock-forming pyroxene mineral with formula . The crystals are monoclinic and prismatic. Augite has two prominent cleavages, meeting at angles near 90 degrees. Characteristics Augite is a solid solution in the pyroxene group ...

and were formed from

basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natura ...

about 1.3 billion years ago. They contain

and

olivine The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers qui ...

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macro ...

s. Their crystallization ages, compared to a crater count chronology of different regions on Mars, suggest the nakhlites formed on the large volcanic construct of either

Tharsis Tharsis () is a vast volcanic plateau centered near the equator in the western hemisphere of Mars. The region is home to the largest volcanoes in the Solar System, including the three enormous shield volcanoes Arsia Mons, Pavonis Mons, and As ...

Elysium Elysium (, ), otherwise known as the Elysian Fields ( grc, Ἠλύσιον πεδίον, ''Ēlýsion pedíon'') or Elysian Plains, is a conception of the afterlife that developed over time and was maintained by some Greek religious and philos ...

, or

Syrtis Major Planum Syrtis Major Planum is a "dark spot" (an albedo feature) located in the boundary between the northern lowlands and southern highlands of Mars just west of the impact basin Isidis in the Syrtis Major quadrangle. It was discovered, on the basis o ...

.Treiman, A.H.
"The nakhlite meteorites: Augite-rich igneous rocks from Mars"
- (PDF) Chemie der Erde 65, p. 203-270, (2005). URL accessed July 30, 2011.

History

A 2017 study dated them to at least four different eruptions from 1416 ± 7 Ma to 1322 ± 10 Ma. It has been shown that the nakhlites were suffused with liquid water around 620 million years ago and that they were ejected from Mars around 10.75 million years ago by an asteroid impact. They fell to Earth within the last 10,000 years.

Possible source crater in Elysium

A 6.5 km diameter crater at in the volcanic plains to the northwest of Elysium Mons has been identified as a possible source. Based on the crater dimensions, the inferred growth rate of the source volcano during that interval is 0.4–0.7 m per Ma, far slower than would be expected for a terrestrial volcano, and implying that Martian volcanism had slowed greatly by that point in history.

Samples

The following samples of nakhlites are known. *

(about 40 samples, total estimated weight ), vicinity of Nakhla, Abu Hommos district, Alexandria Governorate, Egypt, 1911 * Governador Valadares meteorite"Mineralogy of nakhlite Martian meteorites: Implications for their relative burial depths "
Mikouchi, T.; McKay, Gordon; Miyamoto, M., 2006, NASA Technical Reports Server * Lafayette meteorite, 800g, before 1931 *NWA817, 104g, Morocco, 2000 *NWA998, 456g, Morocco, 2001 NWA 998 – 456 grams Nakhlite
/ref> * Y000593 (Yamato 593), NASA.gov
/ref>Imae N., Okazaki R., Kojima H. and Nagao K. (2002a) The first Nakhlite from Antarctica (abs#1483). Lunar Planet. Sci. XXXIII. Lunar Planetary Institute, Houston *Y000749, Imae N., Ikeda Y., Shinoda K., Kojima H. and Iwata N. (2002c) Two Nakhlites from Antarctica: Y000593 and Y000749 (abs). Antarctic Meteorites XXVII, 45-47. Nat. Inst. Polar Res., Tokyo *Y000802, 22g *MIL 03346

Miller Range The Miller Range () is a mountain range extending south from Nimrod Glacier for along the western edge of the Marsh Glacier in Antarctica. Named for J.H. "Bob", now Sir Joseph Holmes Miller, a member of the New Zealand party of the Commonwealth T ...

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...

*MIL 090030, MIL 090032, and MIL 090136, Miller Range, Antarctica

External links

Aerolite Meteorites (Martian meteorites)

References

{{Portal bar, Solar System, Astronomy, Biology Martian meteorites Igneous rocks

History

Possible source crater in Elysium

Samples

See also

External links

References