New technology explores Earth’s Tectonic Hot Spots
By: Veronica Pineda
Acting
as a historian, an observer, and futurist of our planet's movements, University
of Utah Researcher Marie Green uses Magnetotelluric (MT) data to map out the
thermal structure and fluidity underneath the surface of the US Pacific
Northwest Region.
The
Pacific Northwest Region is the most geologically diverse and active area
of our continent to observe due to the dynamics of plate tectonics.
According
to J. Figge’s publication Evolution of
the Pacific Northwest, “The unique characteristic of this region is that
it did not exist prior to Mid-Jurassic time. It consists of
volcanic island
belts and scraps of
ocean floor rocks, which have been
added to the edge of
the continent
over the past 200 million years, and
overprinted by several
episodes of
volcanism and mountain building.”
This
area is situated at the junction of three major tectonic plates (the Gonda, the
Pacific, and the North American plate), otherwise known as the Mendocino Triple
Junction, that slide, sub duct and collide in relation to one another.
“Prior
to the breakup of Pangea and migration of subsequent land masses, Idaho defined
the coastline of what became the North American Plate,” said Green.
As
one continental plate clashes into the next, it sets off a chain reaction of
geological transformation. The Cascadian Mountain Range, the Cascadian Volcanoes,
the Columbia Basin, the geysers of Yellowstone, and the San Andreas Fault among
many other geologic spectacles are evidence of these interactions
MT
data allows scientists to see the anatomy of these features. It acts
as a super detector of oil, mineral deposits, and the physical process of
volcanic and earthquake eruptions.
“For
such a complex region, definitive structural interpretation based purely on
siesmological data may not be sufficient for reliable study of the deep earth
interior,” said Green.
The
obtained MT data can actually look at the changes of Earth’s substructure due
to heat, molten fluidity, and other factors that fluctuate the resistivity.
Green’s
research with the Consortium
for Electromagnetic Modeling and Inversion at the U consists of placing
temporary stations that measure the electric and magnetic field variations from solar winds at any particular time and
location.
These
stations record how long that electric signal takes to reach the receptor,
measuring the rate of decay on the field of that area’s subsurface.
The
time at which it takes the signal to reach the other receptor determines how
resistive the rocks are in the crust and upper mantle.
If
the layer underneath shows low-resistivity, the rock underneath probably has
enough fractures to have had fluid transport.
This
fluid, or molten rock, would act as a lubricant for the tectonic plates to slide and
push against each other causing earthquakes, volcanoes and other hiccups in Earth’s cycle.
Organizations
such as; Earth Scope, US Array, National Science Foundation as well as Oregon
State University are funding this worldwide project to observe and measure the
motions of the Earth's surface, revealing the Earth’s geologic evolution. Also, over 300 stations have been deployed 70
km apart in a grid-like pattern to map the thermal structure of the crust and
upper-mantel from the Pacific Coast to the Rocky Mountain range.
Recently
Green’s Group has found evidence that the heat source of Yellowstone is not
directly underneath. Instead, this channel of heat called a plume is located
40 to 80 km beneath the Snake River Plain and slowly moving further northwest.
"It’s migrating in the subsurface and is
helping break up the crust all through here,” said Green.
The
Snake River Plain extends
400 miles westward from Northwest Wyoming to the Idaho-Oregon border. It
is a broad, flat bowed depression that covers one quarter of the states.
According
to Green, the crust is moving over the upwelling mantle, causing expressions of
basalt, a porous black igneous rock from volcanic activity that cools rapidly
after lava drizzles on the surface.
Under
the measured area, scientists can see the plume’s path as it breaches the Earth’s
crust.
"It
has these wormlike confutes coming from the surface of Yellowstone,” She said.
Scientists
believe that these plumes are the driving mechanism for continental plate
movement.
“From
the data we're analyzing, it now seems like a regional phenomenon,” said Green.
The
images from the MT data systems have mapped the Snake River Plane as the
continuous source of magma from the mantle to Yellowstone—one that continues to
be moving into other fault lines, changing the structure of our earth.
MT data research has only been around since the 1950s, and as it and alternative geological technology develops, scientists can catch another glimpse into the events that that make up the
present world we live in.
 |
| This poster explains in depth the Green's MT research. |
No comments:
Post a Comment