Tagish Lake (meteorite)

Coordinates: 59°42′16″N 134°12′5″W / 59.70444°N 134.20139°W / 59.70444; -134.20139
Source: Wikipedia, the free encyclopedia.
Tagish Lake
Observed fall
Yes
Fall dateJanuary 18, 2000
08:43:42 pst
TKW>10 kilograms (22 lb)
, the site of the "Tagish Lake" meteorite fall

The Tagish Lake meteorite fell at 16:43 UTC on 18 January 2000 in the Tagish Lake area in northwestern British Columbia, Canada.

History

Fragments of the Tagish Lake

seismographs
.

The local inhabitants described the smell in the air following the airburst as

sulfurous and many first thought the blast was caused by a missile.[3]

Meteoroid

The Tagish Lake meteoroid is estimated to have been 4 meters in diameter and 56

noctilucent clouds to the northwest of Edmonton
at sunset, some 12 hours after the event. Of the 1.3 tonnes of fragmented rock, somewhat over 10 kilograms (22 lb) (about 1%) was found and collected.

Specimens

Tagish Lake is classified as a carbonaceous chondrite, type C2 ungrouped. The pieces of the Tagish Lake meteorite are dark grey to almost black in color with small light-colored inclusions, and a maximum size of ~2.3 kg.[2] Except for a greyish fusion crust, the meteorites have the visual appearance of a charcoal briquette.[4] The fragments were transported in their frozen state to research facilities after they were collected by a local resident in late January, 2000. Initial studies of these fresh fragments were done in collaboration with researchers from NASA. Snowfall covered the remaining fragments until April 2000, when a search effort was mounted by researchers from the University of Calgary and University of Western Ontario. These later fragments were mostly found to have sunk into the ice by a few cm to more than 20 cm, and had to be collected out of meltwater holes, or cut in icy blocks from the frozen surface of Tagish Lake.

Fragments of the fresh, "pristine" Tagish Lake meteorite totaling more than 850 g are currently held in the collections at the Royal Ontario Museum and the University of Alberta. "Degraded" fragments from the April–May 2000 search are curated mainly at the University of Calgary and the University of Western Ontario.

Analysis and classification

Analyses have shown that Tagish Lake fragments are of a primitive type, containing unchanged stellar dust granules that may have been part of the cloud of material that created the Solar System and Sun. This meteorite shows some similarities to the two most primitive carbonaceous chondrite types, the CI and CM chondrites; it is nevertheless quite distinct from either of them. Tagish Lake has a much lower density than any other type of chondrite and is actually composed of two somewhat different rock types. The major difference between the two lithologies is in the abundance of carbonate minerals; one is poor in carbonates and the other is rich in them.[5]

The meteorite contains an abundance of

organic materials, including amino acids.[6] The organics in the meteorite may have originally formed in the interstellar medium and/or the solar protoplanetary disk, but were subsequently modified in the meteorites' asteroidal parent bodies.[7]

A portion of the carbon in the Tagish Lake meteorite is contained in what are called nanodiamonds—very tiny diamond grains at most only a few micrometers in size. In fact, Tagish Lake contains more of the nanodiamonds than any other meteorite.[8]

As with many carbonaceous chondrites,

Type 2 specimens in particular, Tagish Lake contains water. The meteorite contains water-bearing serpentinite and saponite phyllosilicates;[10][11] gypsum has been found, but may be weathering of meteoritic sulfides. The water is not Earthly contamination but isotopically different from terrestrial water.[12][13]

The age of the meteorite is estimated to be about 4.55 billion years thus being a remainder of the period when the solar system was formed.

Origin

Based on eyewitness accounts of the

Whitehorse, Yukon accurately constrained the ground track azimuth from either side. It was found that the Tagish Lake meteorite had a pre-entry Apollo type orbit that brought it from the outer reaches of the asteroid belt. Currently,[when?
] there are only eleven meteorite falls with accurately determined pre-entry orbits, based on photographs or video recordings of the fireballs themselves taken from two or more different angles.

Further study of the reflectance spectrum of the meteorite indicate that it most likely originated from 773 Irmintraud, a D-type asteroid.

Comparisons

The double, and not the expected single, plume formation of debris, as seen in video and photographs of the 2013 Chelyabinsk meteor dust trail and believed by Peter Brown to have coincided near the primary airburst location, was also pictured following the Tagish Lake fireball,[14] and according to Brown, likely indicates where rising air quickly flowed into the center of the trail, essentially in the same manner as a moving 3D version of a mushroom cloud.[15]

See also

References

  1. ^ a b Meteoritical Bulletin Database: Tagish Lake
  2. ^
    PMID 11030647
    .
  3. ^ "Morning Light - The Secret History of the Tagish Lake Fireball by MASSACHUSETTS INSTITUTE James Scott Berdahl B.S.Geology Massachusetts Institute of Technology,2008" (PDF). Archived from the original (PDF) on 2014-04-04.
  4. ^ Geological Survey of Canada. Meteorite fragment photo
  5. Bibcode:2002psrd.reptE..68M
    . Retrieved 2009-05-02.
  6. ^ NASA, Asteroid Served Up "Custom Orders" of Life's Ingredients, June 9, 2011 (accessed 23 November 2013)
  7. S2CID 526440
    .
  8. S2CID 129629587
    .
  9. S2CID 206542013
    .
  10. doi:10.1111/j.1945-5100.2010.01043.x
    .
  11. S2CID 15242427
    .
  12. ^ Gilmour, C; Herd, C; Cloutis, E; Cuddy, M; Mann, P (2016). Water abundance in the Tagish Lake meteorite from TGA and IR spectroscopy: Evaluation of aqueous alteration. 47th LPSC.
  13. doi:10.1111/j.1945-5100.2002.tb00870.x
  14. ^ "Hypervelocity reentries".
  15. ^ "WGN, the Journal of the IMO 41:1 (2013) A Preliminary Report on the Chelyabinsk Fireball/Airburst Peter Brown" (PDF).
  • Universe: The Definitive Visual Dictionary, Robert Dinwiddie, DK Adult Publishing, (2005), pg. 222.
  • Mittlefehldt, D.W., (2002), Geochemistry of the ungrouped carbonaceous chondrite Tagish Lake, the anomalous CM chondrite Bells, and comparison with CI and CM chondrites, Meteoritics and Planetary Science 37: 703–712. See summary of the article.

External links

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