Eltanin - part 1 of 2

[Bernd Pauli HD <bernd.pauli@lehrer1.rz.uni-karlsruhe.de>]

Hi again!

J.A. Bostwick et al. (1995) Asteroid sample return mission II: Eltanin
recovered (abs. Meteoritics 30, 490 ): The Late Pliocene impact of the
Eltanin asteroid produced a truly unique deposit in the known
sedimentary record. It is the only known impact into a deep-ocean basin.
Evidence of this impact was first discovered as an Ir anomaly in
sediments from core El 3-3 recovered by the USNS Eltanin in 1964.
Further examination of these sediments revealed that Ir was largely
contained (ca. 50%) within mm-sized grains of vesicular impact melt and
that  several % of the impact debris consists of unmelted meteorite
fragments. The unmelted fragments are from a meteoritic basalt similar
to howardites and mesosiderites and have been named the Eltanin
meteorite. Trace components of the impact debris include rare metal
grains and glassy spherules containing megnesioferrite spinel. The
spherules may be impact vapor condensates. Thus the impact debris
contains materials derived from the unaltered projectile, an impact melt
(a simple mixture of projectile and salts from the seawater target), and
an impact vapor cloud. Assuming that the impact site was near core El
3-4 (57° 47.2' S and 90° 47.6' W), the site with the most debris, a
conservative estimate of the minimum asteroid diameter was about 500 m,
although it could have been as large as 2 km.


Regards,

Bernd



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