Autor Thema: Meteor mit Fragmentation und Detonation, 17.10.12, 19'42 PDT, California  (Gelesen 13343 mal)

Offline karmaka

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Re: Meteor mit Fragmentation und Detonation, 17.10.12, 19'42 PDT, California
« Antwort #60 am: August 11, 2014, 17:06:02 Nachmittag »
 :smile:

Hier ist das Oeuvre als PDF in Gesamtlänge:

Fall, Recovery and Characterization of the Novato L6 Chondrite Breccia

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Offline karmaka

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Re: Meteor mit Fragmentation und Detonation, 17.10.12, 19'42 PDT, California
« Antwort #61 am: August 14, 2014, 09:57:24 Vormittag »
Records of the Moon-forming impact and the 470 Ma disruption of the L chondrite parent body in the asteroid belt from U-Pb apatite ages of Novato (L6)

Yin, Q.-Z., Zhou, Q., Li, Q.-L., Li, X.-H., Liu, Y., Tang, G.-Q., Krot, A. N. and Jenniskens, P. (2014)
Meteoritics & Planetary Science. doi: 10.1111/maps.12340

LINK

Zitat
Abstract

Novato, a newly observed fall in the San Francisco Bay area, is a shocked and brecciated L6 ordinary chondrite containing dark and light lithologies. We have investigated the U-Pb isotope systematics of coarse Cl-apatite grains of metamorphic origin in Novato with a large geometry ion microprobe. The U-Pb systematics of Novato apatite reveals an upper intercept age of 4472 ± 31 Ma and lower intercept age of 473 ± 38 Ma. The upper intercept age is within error identical to the U-Pb apatite age of 4452 ± 21 Ma measured in the Chelyabinsk LL5 chondrite. This age is interpreted to reflect a massive collisional resetting event due to a large impact associated with the peak arrival time at the primordial asteroid belt of ejecta debris from the Moon-forming giant impact on Earth. The lower intercept age is consistent with the most precisely dated Ar-Ar ages of 470 ± 6 Ma of shocked L chondrites, and the fossil meteorites and extraterrestrial chromite relicts found in Ordovician limestones with an age of 467.3 ± 1.6 Ma in Sweden and China. The lower intercept age reflects a major disturbance related to the catastrophic disruption of the L chondrite parent body most likely associated with the Gefion asteroid family, which produced an initially intense meteorite bombardment of the Earth in Ordovician period and reset and degassed at least approximately 35% of the L chondrite falls today. We predict that the 470 Ma impact event is likely to be found on the Moon and Mars, if not Mercury.

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Re: Meteor mit Fragmentation und Detonation, 17.10.12, 19'42 PDT, California
« Antwort #62 am: August 28, 2014, 00:41:38 Vormittag »
Novato jetzt auch als ein 'Research Highlight' in der neuesten Ausgabe von Nature:

Collision history written in rock

Nature 512, 350 (28 August 2014) doi:10.1038/512350c

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