[meteorite-list] Eltanin - Part 1 of 2

From: bernd.pauli_at_paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: Wed Sep 6 14:14:55 2006
Message-ID: <DIIE.0000008800000CB0_at_paulinet.de>

Bostwick J.A. 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.
Received on Wed 06 Sep 2006 02:13:10 PM PDT