Chicxulub Spherules Reveal Details of Catastrophic K-T Fireball

Paul H bristolia at yahoo.com
Wed Mar 23 12:53:17 EST 2005

"Mystery minerals formed in fireball from colliding
asteroid that destroyed the dinosaurs"
Innovation Report, March 23, 2005

http://www.innovations-report.de/html/berichte/studien/bericht-42101.html

"Scientists at the American Museum of Natural History
and the University of Chicago have explained how a
globe-encircling residue formed in the aftermath of
the asteroid impact that triggered the extinction of
the dinosaurs. The study, which will be published in
the April issue of the journal Geology, draws the
most detailed picture yet of the complicated
chemistry of the fireball produced in the impact."

Extinction Mystery Discovered - Extraterrestrial Cause??

Paul H bristolia at yahoo.com
Wed Mar 9 17:16:36 EST 2005

Mystery Undersea Extinction Cycle Discovered
John Roach, National Geographic News, March 9, 2005
http://news.nationalgeographic.com/news/2005/03/0309_050309_extinctions.html

++++++++++++++++++++++++

Rohde, R. A., and Muller, R. A., 2005, Cycles in
fossil
diversity. Nature. vol. 434, no. 7030, pp. 208-210.

doi:10.1038/nature03339
http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v434/n7030/abs/nature03339_fs.html

++++++++++++++++++++++++

Kirchner, J. W., and Weil, A., 2005, Biodiversity:
Fossils make waves. Nature. vol. 434, no. 7030, pp.
147-148.

"Extinction of the dinosaurs in North America"

Paul H bristolia at yahoo.com
Tue Mar 8 23:35:30 EST 2005

GSA TODAY Science Article:
The extinction of the dinosaurs in North America
http://www.eurekalert.org/pub_releases/2005-02/gsoa-mga022805.php

Fastovsky, D. E., and Sheehan, P. M., 2005, The
Extinction
of the Dinosaurs in North America. GSA Today. vol. 15,

no. 3, pp. 4-10. doi: 10.1130/1052-5173

http://www.gsajournals.org/gsaonline/?request=get-abstract&doi=10.1130%2F1052-5173(2005)15%3C4:TEOTDI%3E2.0.CO%3B2

http://www.gsajournals.org/gsaonline/?request=get-document&doi=10.1130%2F1052-5173(2005)15%3C4:TEOTDI%3E2.0.CO%3B2

"Did the dinosaurs really go abruptly extinct 65
million
years ago at the Cretaceous-Tertiary ("K-T") time
boundary, or was their K-T extinction the end result
of a gradual decline over millions of years? The
imperfect record available from scarce dinosaur
remains has made this question a true enigma
and the source of a long-standing and contentious
debate. David E. Fastovsky and Peter M. Sheehan
conclude, after a careful review of the fossil record
from the best-documented dinosaur sites (in
North America), that the extinction was indeed
geologically instantaneous. The authors argue
that the sudden die-off was different in scope
from previous fluctuations in dinosaur diversity
through the dinosaurs' 160 million years on Earth.
The authors consider the dinosaurs to have been
direct casualties of the K-T impact of an asteroid
with Earth and review several potential explanations
for the mechanism of the extinction. All of these are
concordant with the asteroid impact as the ultimate
cause."

Discovery of distal ejecta from Sudbury impact event

Paul H bristolia at yahoo.com
Tue Mar 8 23:26:46 EST 2005

Discovery of distal ejecta from the 1850 Ma Sudbury
impact event
from "March Geology and GSA TODAY" media highlights
at:

http://www.eurekalert.org/pub_releases/2005-02/gsoa-mga022805.php
http://www.gsajournals.org/gsaonline/?request=get-current-toc&issn=0091-7613

Addison, W. D., and others, 2005, Discovery of
distal ejecta from the 1850 Ma Sudbury impact
event. Geology: Vol. 33, No. 3, pp. 193–196.

Addison et al. announce the discovery of impact
ejecta from the Sudbury, Ontario, Canada,
structure, the second largest and third or fourth
oldest extraterrestrial Earth impact site. At 1.85
billion years old, these Paleoproterozoic ejecta
are three times older than the previous oldest
dated ejecta linked to a specific impact (Acraman,
Australia, 0.59 billion years old). It is also larger
than the well-known Chicxulub, Mexico (0.065
billion years old) impact linked to the extinction
of the dinosaurs and many other species. The
young Chicxulub impact, particularly its well-
preserved worldwide ejecta debris layers, have
produced criteria to judge other large ejecta
deposits. Foremost is the occurrence of sets of
microscopic parallel lamellae in quartz and
feldspar grains produced by the intense shock
generated at the point of impact. Secondarily,
the impact generated a megaplume of vaporized,
melted, and crushed crustal rocks, creating molten
droplets containing bubbles of gas, and larger
accreted balls of dust and rock shards called
impact accretionary lapilli. These features, and
more, are seen in the Sudbury debris. The debris
(ejecta) studied here, landed 650 km west northwest
of Sudbury near Thunder Bay, Ontario, Canada, and
875 km west of Sudbury near Hibbing, Minnesota,
United States. This huge impact likely deposited
debris all around Earth, but it is very difficult to
find because so much of the evidence has been
destroyed in the recycling of Earth's crust by plate
tectonics. Life at the time of the Sudbury impact
was confined to the oceans and consisted of
unicellular and colonial unicellular organisms. So
far, Addison et al. have found no evidence of
extinction of this life. However, future studies may
link this impact and its ejecta with changes in the c
lassic Gunflint Iron Formation unicellular organisms
and their photosynthetic microbial mats, which
helped produce Earth's atmospheric oxygen.