Transcript 2. Summarize results from the CD-ROM experiment

Goals (and conclusions)
1. Summarize the evolution of the Laurentian craton:
segmented and heterogeneous nature of the lithosphere
the need for 4-D integrated studies within EarthScope.
2. Summarize results from the CD-ROM experiment:
pose alternative hypotheses for reddite and blueite
the need for 3-D deployments of the flexible array.
3. Summarize the Southwestern U.S. EarthScope
“superexperiment” proposal:
a new paradigm for integrated and inclusive regional
experiments within EarthScope.
4. Muse about the best targets for a Northern Rockies
“Superexperiment”:
towards a single integrated EarthScope experiment in the
northern Rocky Mountains.
History and structure of the Wyoming Archean province–
oldest parts of North American lithosphere
secular change in lithospheric processes?
Extent of ~ 2.0 Ga Paleoproterozoic juvenile crust?
Nature of Paleoproterozoic rifting in creating long-lived
lithospheric boundaries
Great Falls Tectonic Zone and Vulcan Structure as
parts of the greater Trans-Hudson:~1.9-1.8 Ga
continent- continent collisions; “birth” of Laurentia
Extent of Trans-Hudson age tectonism beneath
Proterozoic accreted terranes
Yavapai and Mojave provinces: interaction of collisional
and accretionary orogens ~1.8 -1.7 Ga
Figure 3
Quartzite-rhyolite successions
occur late in Yavapai orogeny
Mazatzal province:
~1.65 Ga juvenile crust,
includes the Labradorian province
~1.65 Ga Mazatzal plutons
stitch pre-1.65 Ga accreted crust
1.45-1.35 Ga Belt Basin
related to accretion in south??
Assembly of Rodinia:
1.3-1.0 juvenile crust
accreted during the
Grenville orogenic cycle,
1.1 Ga Midcontinent
and related rifts:
mafic dike swarms,
Grenville-aged extension
& widespread normal faulting
Western margin of Laurentia
formed via 780-685 Ma breakup
of Rodinia, Gunbarrel Dikes
& Windermere Supergroup
Long-lived accretionary
plate margin in southern
Laurentia: 1800 - 1000 Ma
The nature and origin of mantle
heterogeneity– a problem
best solved in the Rockies
Figure 3
Body Wave
Tomography:
RISTRA
Small-scale
convection?
Small-scale
convection?
Comparing
CD-ROM and
RISTRA:
anomalies align
along
Precambrian
structures? The
need for 3-D
EarthScope
Southwestern U.S.
Superexperiment:
Diverse tectonic
elements
in the Southwest
require
a 3-D seismic
experiment
integrated with
geology
EarthScope
Southwestern U.S.
Superexperiment:
Densification of
Bigfoot (blue grid)
to achieve 3-D
resolution of
regional tectonic
provinces and 10km-scale
mantle velocity
contrasts, and 4-D
understanding of
lithospheric
evolution
MT images need to be integrated with seismic, geodetic,
and geologic datasets
What is the
extent to
which
topography is
influenced by
crustal versus
mantle density
variations and
when and how
did the density
structure
develop?
The nature and origin of mantle
heterogeneity– a problem
best solved in the Rockies
Mantle to groundwater interconnections via analysis of deeply sourced
CO2 springs containing mantle-derived helium
Conclusions
1. The crust and upper mantle are segmented
and highly heterogeneous and cannot be well
understood without a 4-D integrated approach
within EarthScope.
2. There are two models to explain large velocity
transitions (redite and blueite): 1) small scale
asthenospheric convection, versus 2)
preservation of old compositional provinces:
We need 3-D deployments of the flexible array
to resolve the relative importance of each
model.
Goals and Conclusions
3. EarthScope needs to forge a new paradigm for
large integated, collaborative, and inclusive
regional experiments.
4. A Northern Rockies “Superexperiment”:
could propose a single integrated experiment
that addresses an integrated set of uniquely
well-posed problems in the northern Rocky
Mountains: Yellowstone, Archean Wyoming
province, west edge of Laurentia, and
neotectonics of the northern Rockies.