[meteorite-list] Mysterious Circular Structure Near Chemult, Oregon not so mysterious anymore

From: Thaddeus Besedin <endophasy_at_meteoritecentral.com>
Date: Sat, 13 Oct 2007 02:44:52 -0700 (PDT)
Message-ID: <857543.40855.qm_at_web62504.mail.re1.yahoo.com>

List,
This structure is a spreading zone, in an extensional
basin, and most of its morphology is due to the
chemult graben fault system, a normal (in geologic
terms, as opposed to a reverse fault system) fault
system which makes the structure a horst/volcanic arc
(see calderas in images).
The Western portion seems to be known as Walker Rim,
but I could be wrong.
Spreading of crust allowed basaltic flows to emerge,
not an impact (the entire Great Basin is structurally
a parallel series of normal faults and Horst/Graben
blocks). The
ring of extinct basaltic cones,emerged from a single,
very ancient primary caldera, intruded later during a
second period of volcanic activity, probably
synchronically corresponding to flood basalt extrusion
on the Columbia Plateau. Palinspastic reconstruction
may show a rotational tendency for this axial
structure as a tensional center, erupting as the
valley floor spread.
I worked for a few hours in Global Mapper 8.3 on
these, with most of the time spent waiting for
photobucket uploads (painfully slow). These are
digital elevation model images, Landsat 7 images,
fault and lithologic overlays, topographic profiles,
and 3D image compilations of the above. Enjoy.
http://i237.photobucket.com/albums/ff316/endophasy/ORstruct30m1wlitho.jpg
http://i237.photobucket.com/albums/ff316/endophasy/ORstructlandsat7wlitho.jpg
http://i237.photobucket.com/albums/ff316/endophasy/vert65withLandsat7andlitho.jpg
http://i237.photobucket.com/albums/ff316/endophasy/profileW-E.jpg
http://i237.photobucket.com/albums/ff316/endophasy/W-EprofileonLANDSAT7.jpg
http://i237.photobucket.com/albums/ff316/endophasy/N-SprofileonLANDSAT-1.jpg
http://i237.photobucket.com/albums/ff316/endophasy/N-SprofileonLANDSAT.jpg
http://i237.photobucket.com/albums/ff316/endophasy/faultslabelslithoTN.jpg
http://i237.photobucket.com/albums/ff316/endophasy/vert65viewS3Dlithofaultslabels.jpg
http://i237.photobucket.com/albums/ff316/endophasy/faults30mDEMnolabels.jpg
-Thaddeus Besedin
--- Thaddeus Besedin <endophasy at yahoo.com> wrote:

>
> I'm downloading DOQQ and DEM data from the USGS
> seamless server (I was going to make some 3D images
> of
> Mt. Hood for a friend anyway). I'll try to post
> links
> to my images, including a simple profile analysis
> and
> vertically exaggerated 3D images. I hope that the
> data
> is available in 1/3-arc second resolution. At 3-arc
> second resolution, the structure does have a
> prominent
> sidewall, but is still, according to a lithological
> GIS layer I have currently loaded, within the
> boundaries of "mafic volcanic flow," e.g. basalts,
> and
> not material associated with pyroclastic, siliceous
> lavas (dacite, andesite) that form the Cascade
> stratovolcanoes. Mt. Mazama, the name given to the
> former stratovolcano that currently we call crater
> lake, was radically altered by its last major
> eruption, 7,627 BP
>
(http://geology.geoscienceworld.org/cgi/content/abstract/27/7/621).
> Its tephra layer is an important chronological
> constraint in geochronology and in archaeology, and
> is
> present in various thicknesses (following monotonic
> decrement, but distributed much more extensively
> NNE)
> from Northern California to Saskatchewan to Montana.
> ... off to work.
> Thaddeus --- Jerry <grf2 at verizon.net> wrote:
>
> > Cool news ie. impact causing HOT SPOT. Sooooo
> Cool.
> > If we generalize [which
> > I presume we must not without scientific data to
> > support the supposition]
> > Yellowstone, Sunset Crater, etc. are all impact
> > sites caused when the crust
> > was so deeply wounded the mantle material persists
> > in melting whatever
> > crustal material attempts to scab the wound!
> > SUPER COOL!!
> > Jerry Flaherty
> > ----- Original Message -----
> > From: <pkmorgan at ctcweb.net>
> > To: "Stefan Brandes" <brandes at gmx.at>
> > Cc: <meteorite-list at meteoritecentral.com>
> > Sent: Friday, October 12, 2007 5:01 PM
> > Subject: Re: [meteorite-list] Mysterious Circular
> > Structure Near Chemult,
> > Oregon
> >
> >
> > > Looks like something fun to check out either
> way.
> > I've been meaning to
> > > get over and explore that general area. Of
> course
> > it would have to be
> > > pretty obvious for me to notice anything :-)
> > >
> > > By the way, I have heard a theory that there was
> a
> > large strike at some
> > > point in central Oregon causing a "hot spot" in
> > the mantle (?) which has
> > > since migrated through the Snake River plain in
> > southern Idaho and now
> > > lies beneath Yellowstone National Park resulting
> > in all of the geothermal
> > > activity in that area.
> > >
> > > Thanks for sharing!
> > >
> > > Phil
> > >
> > >
> > >> Interesting formation :
> > >>
> > >>
> >
>
http://epod.usra.edu/archive/epodviewer.php3?oid=382976
> > >>
> > >> any ideas?
> > >>
> > >> Stefan
> > >> ______________________________________________
> > >> Meteorite-list mailing list
> > >> Meteorite-list at meteoritecentral.com
> > >>
> >
>
http://six.pairlist.net/mailman/listinfo/meteorite-list
> > >>
> > >
> > >
> > > ______________________________________________
> > > Meteorite-list mailing list
> > > Meteorite-list at meteoritecentral.com
> > >
> >
>
http://six.pairlist.net/mailman/listinfo/meteorite-list
> >
> >
> > ______________________________________________
> > Meteorite-list mailing list
> > Meteorite-list at meteoritecentral.com
> >
>
http://six.pairlist.net/mailman/listinfo/meteorite-list
> >
>
>
>
>
>
____________________________________________________________________________________
> Shape Yahoo! in your own image. Join our Network
> Research Panel today!
>
http://surveylink.yahoo.com/gmrs/yahoo_panel_invite.asp?a=7
>
>
>
> ______________________________________________
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
>
http://six.pairlist.net/mailman/listinfo/meteorite-list
>



      ____________________________________________________________________________________
Catch up on fall's hot new shows on Yahoo! TV. Watch previews, get listings, and more!
http://tv.yahoo.com/collections/3658
Received on Sat 13 Oct 2007 05:44:52 AM PDT