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24th August, 2008
Dear WM, As part of my "Integrating
Research and Education" project (funded by NSF),
we did a number of "guided discovery exercises" for
students to explore interesting and important topics.
Kent Ratajeski did a nice unit on "Is
Yellowstone Volcanism Caused by a Deep-Seated Mantle
Plume?". Please feel free to
link to our metadata
page about this site if appropriate
on your Mantle Plumes site.–Dave Mogk
22nd August, 2008
Dear WM, I propose that the well-known
acronym “OIB”,
for “ocean island basalts”, is henceforth
used to denote “oceanic
intraplate basalts”.
There are two reasons for my proposal:
(i) Islands are merely the tops of submarine
volcanoes and the term “ocean
island basalt” does not include the thousands
of seamounts that lie scattered throughout the Pacific
and other ocean basins. Most of these seamounts do
not define systematic chains, a fact that is of relevance
to the plume hypothesis (the “galaxy
effect”).
(ii) The term “ocean island
basalt” by itself does not say anything about
the intraplate origin
of the islands in question. There are oceanic island
arcs related to subduction which are a plate boundary
phenomenon. “Ocean
island basalt” should include the basalts of
the oceanic island arcs, inasmuch as they are “oceanic”, “islands”,
and erupt “basalt”.
Thus, OIB and IAB are not really exclusive.
Of course, there are rocks other than basalt in arcs,
and I am happy if even the “B” is replaced
by something general – simply
R for “rocks?”.
But if the term "OIB" is to be continued, then,
to avoid these problems, and to ensure terminological
accuracy, OIB should be used for “Oceanic Intraplate
Basalts”.
If used in this way, the term means that the said basalts
are “oceanic”,
and formed by “intraplate” mechanisms,
and therefore island arc basalts (IABs) would be automatically
excluded.
Comments are welcome.–Hetu Sheth
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