|Basic information||Name: Creston|
This is an OFFICIAL meteorite name.
Abbreviation: There is no official abbreviation for this meteorite.
Observed fall: Yes, confirmed fall
Year fell: 2015
Country: United States
Mass: 688 g
This is 1 of 9874 approved meteorites (plus 3 unapproved names) classified as L6. [show all]
Search for other: L chondrites, L chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
|Comments:||Approved 23 Nov 2015|
Writeup from MB 104:
Creston 35°34’13"N, 120°28’21"W
California, United States
Confirmed fall: 2015 Oct 23
Classification: Ordinary chondrite (L6)
History: (Robert Ward, Anne Marie Ward, Robert Matson, Marc Fries) On 23 October at 22:47 PDT (24 October 2015, at 05:47 UTC) a large fireball lit up the rolling hills of wine country east of Paso Robles. The bolide displayed a multitude of colors as it broke up. The fireball was captured on at least four all-sky cameras in Parker, Arizona; Riverside, California; El Segundo, California; and the SETI Institute CAMS all-sky system in Sunnyvale, California. Dozens of witnesses close to the ground path heard sonic booms shortly after the fireball terminated. Confirming these accounts, sonic boom signatures were recorded by three California seismic stations, allowing triangulation of the approximate fall zone. Six Doppler radar returns acquired from the NOAA NEXRAD weather radar network were used to further constrain the fall location. The earliest radar signature appears in imagery from the KVTX (Los Angeles, California) radar at an altitude of 16.2 km above sea level (ASL) at 05:47:57.6 UTC - just 12 s after the meteor first appears in the Riverside video. KVBX (Vandenberg AFB, California) recorded signatures of falling meteorites at 05:49:40.3, 05:51:08.9 and 05:53:43.3 UTC at altitudes of 5.6 km, 6.7 km and 1.2 km, respectively; KHNX (San Joaquin, California) recorded several returns at 05:51:57.3 at an altitude of 3.9 km. Finally, KMUX (San Francisco) recorded a pair of returns at 16.2-km altitude at 06:00:41.7. This last return is likely the signature of fine dust, given its altitude and timing, which correlates with eyewitness accounts of a visible smoke trail left by the fireball. Based on the relative timing and altitude of the earlier five radar returns, the estimated masses of falling meteorites at those locations vary from sub-gram to as much as 10 kg for the earliest return. Equipped with the radar-cued search area, Robert and Anne Marie Ward located the first stone on 27 October, along the road (California Route 41), 7.3 km northeast of Creston, San Luis Obispo County. The stone broke upon impact, with a total mass of 395.7 g. As of 10 November, 108 g, 102 g and 82 g stones have also been recovered.
Physical characteristics: Stone covered with matte to shiny black fusion crust up to 1 mm thick. Exterior rounded with a few broad regmaglypts. Interior is light grey and sprinkled with small (<1 mm metal and troilite). Chondrules not visible. Stone criss-crossed with shock veins, some to 2 mm thick. Sample also broke along well-developed slickenside surfaces that are shiny and black.
Petrography: (L. Garvie, ASU) A polished microprobe section shows dominantly coarse-grained recrystallized minerals. Only two BO chondrules were recognizable in the section. Plagioclase abundant to 200 μm. Chromite grains to 300 μm are anhedral with rounded outlines. Troilite grains to 300 μm and largely single crystal and lacking shock lamellae except where near shock veins. Scattered Ca-Cl and Ca-Mg-Na phosphates to 200 μm. Fe-Ni metal grains to 400 μm. Metal grains range from kamacite with weakly developed Neumann bands, to polycrystalline, to those with tetrataenite rims and cores of dark-etching plessite or acicular kamacite. Section shows a well-developed 1-mm thick shock vein with 50-μm blebs and spheres of Fe/Fe-S. Fine-grained melt pockets are present but rare.
Geochemistry: (L. Garvie, ASU) Olivine, Fa24.8±0.4 (n=11), Fe/Ni=47.3±2.5, and low Ca pyroxene, Fs21.1±0.2Wo1.3±0.2 (n=14), Fe/Mn=28.1±1.3.
Classification: Ordinary chondrite, L6.
Specimens: 21 g and one polished mount at ASU.
ASU: Center for Meteorite Studies, Arizona State University, Tempe, Arizona 85287-1404, United States; Website (institutional address; updated 14 Jan 2012)
SETI: SETI Institute, Carl Sagan Center, 189 Bernardo Avenue, Mountain View, California 94043, United States (institutional address; updated 22 May 2012)
Ward: No contact information provided. (private address)
|References:||Published in Meteoritical Bulletin, no. 104, in preparation (2015)|
This is 1 of 253 approved meteorites from California, United States (plus 24 unapproved names)
This is 1 of 1787 approved meteorites from United States (plus 352 unapproved names) (plus 28 impact craters)
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