Western North America microcontinent bigger than previously thought?

[CORed]

Obviously, it's Lisa's fault.

Which fault is Lisa's? How exactly does one end up owning a fault?

 

[AlBell]

A question for our geologists:

Is the New Madrid fault zone probably the western-most suture of Appalachian mountain building?

 

[Travis]

Well, North America, except for the Canadian Shield which is partially excepted, is accreted. There are faults everywhere, even in Northern Ohio, and lots of places you wouldn't expect. The Rockies and the Basin and Range are a collection of more faults than anyone knows about. Looking at some of the large mountains you can see faulting along a half-dozen planes. The Southeast has a variety of faults. The west coast has so many faults it's worse than the Rockies.

Then it has Long Valley and Yellowstone, and maybe something going on in Cascadia.

So North America is no Australia, with one nice solid bit of rock under it. It's a collection continent, made up of a whole lot of former continents, with both rifts and subduction faults in unexpected places. I have to say that perhaps that's why it was so uninhabited until after the last ice age. It doesn't go kaboom very often,but when it does...

I live not far from Long Valley.

Needless to say being proximate to a supervolcano is sometimes kinda weird.

 

[jj]

I live not far from Long Valley.

Needless to say being proximate to a supervolcano is sometimes kinda weird.

Yeah. I think "down boy" is the only thing to say to Long Valley. It's rather hot at the minute, with Mammoth Mountain throwing off all that CO2, isn't it?

Then again, I live halfway between Baker and Rainier.

Additionally, analysis of continuous GPS data over the last several months show continued modest inflation within the caldera. Ground motion is directed upward and away from the caldera's center, with a maximum uplift rate between 2 and 3 cm/yr. Horizontal deformation is similar in magnitude, with a N/S extension rate across the caldera's center of about 3 cm/yr. These rates of deformation are comparable to those observed in 2002-2003, and well below the rates seen in the late 1990s.

http://volcanoes.usgs.gov/observatories/calvo/calvo_activity_update_last10.html

 

[Dinwar]

A question for our geologists:

Is the New Madrid fault zone probably the western-most suture of Appalachian mountain building?

I don't believe so. I think it's part of a failed rift. That said, faults do tend to reactivate, so it may be possible that they're somehow related. I'd definitely be interested in what our more hard-rock friends have to say.

 

[Travis]

Yeah. I think "down boy" is the only thing to say to Long Valley. It's rather hot at the minute, with Mammoth Mountain throwing off all that CO2, isn't it?

Then again, I live halfway between Baker and Rainier.


http://volcanoes.usgs.gov/observatories/calvo/calvo_activity_update_last10.html

If Long Valley does ever erupt life for me will get very interesting and scary fast. We have table mountains nearby that are remnants from its last eruption cycle.

 

[GT/CS]

Well then you may find this of interest.

Upswing in Earthquakes in the Long Valley Caldera Region of California

 

[Axxman300]

I grew up with the idea that the area west of the San Joaquin Fault would eventually split off and become a micro continent.

But lately I've stumbled upon the idea that this might not be so. That the rift might actually be further east in an area known as Walkers Lane of which Death Valley serves as part.

I find this an intriguing prospect as the land area that would eventually rift away from North America will be much larger.

How formalized is this hypothesis in the geologic community? Would this account for volcanism in the Sierra Nevada such as that around Mono Lake including the giant volcano at Long Valley?

The driving tectonic engine in California is the San Andreas fault. Everything west of the fault from Baja to just north of San Francisco is moving north. This movement has forced the sea floor upward creating the the mountain ranges to the west. It continues to move north. So in 30 million years (or so) San Francisco will be in the Gulf of Alaska - or stall out around Oregon. It depends on the subduction zone.

The key is the northern motion, nothing will move west unless it's pushed west by a rising land mass.

Anyway, it's doubtful there will be anything resembling humans running around here by the time any of this has played out.