Group 1: Erosional history of the Rockies

1
Group 1 Erosional history of the Rockies

• Aspen Anomaly is a composite feature that results
  from buoyancy modification during
• Larmide
• Oligocene
• Plio-Quaternary

2
Group 1 Erosional history of the Rockies

• Laramide
• Thermochronologic questions
• How much denudation during Larmide in AA?
• How does it compare to other regions (Front
  Range, Zuni)?
• Was thermal history anomalous relative to other
  Larmide uplifts?

3
Group 1 Erosional history of the Rockies

• Oligocene
• Thermochronologic questions
• Denudation/Heat flow in High Plains (Denver
  Basin) and Western Slope (Piceance Basin)?
• Geologic questions
• Landscape reconstruction - how did constructional
  edificices of San Juans, West Elks influence
  drainage?

4
Group 1 Erosional history of the Rockies

• Late Miocene-Quaternary
• Thermochronologic questions
• When did rapid incision begin in Gunnison region?
• Drill hole study
• Geologic questions
• Time-space evolution of incision
• Can incision patterns result entirely from
  upstream migration of knickpoints related to
  cutting of Grand Canyon?
• Alternatively, do patterns require additional
  components from isostasy, tectonics?

5
Group 1 Erosional history of the Rockies

• Work plan - Laramide
• Collection of samples along elevation traverses
  in AA region (Kelley)
• Analysis of archive samples (Kelley)

6
Group 1 Erosional history of the Rockies

• Work plan - Oligocene
• Collection of core samples - Denver Basin,
  Piceance Basin (Kelley)
• Incorporate Oligocene horizons in longitudinal
  profile reconstructions (Leonard - Arkansas,
  Sandoval/Karlstrom/Aslan - Gunnison)

7
Group 1 Erosional history of the Rockies

• Work Plan - Late Miocene-Quaternary
• Identify appropriate well locations for thermal
  studies, gain access to core (Aslan, Kelley)
• Burial ages at Gunnison (Sandoval)/Drilling at
  Cactus Park
• Miocene paleotopographic reconstructions - GIS
  development, field surveys, new dates
• Preliminary modeling of incision rates and
  patterns expected from cutting of Grand Canyon
• Testing of incision models against incision
  history in Gunnison region
• Discharge/area data for Colorado watershed
• New incision rate data - gt640 ka and lt640 ka
• Prelminary models of isostatic response

8
Group 1 Erosional history of the Rockies

• Integration
• Microseismic distribution in region - evidence
  for active faulting?
• Role of dissolution in incision
• Strength of lithosphere - isostatic consequences
  of incision
• Large-scale topographic analysis
• Static versus dynamic support of topography

9
Group 1 Erosional history of the Rockies

• Resources
• Web-access to communal products
• Data
• Derivative products
• Bi-annual meetings of subgroups
• Late February - early April working group
  meeting in Grand Junction
• Tutorials on stream profile analysis
• Data compilation
• Field trips

10
Group 1 Erosional history of the Rockies

• Deliverables (1 year)
• Gunnison incision history - thesis/ms
  (Sandoval/Karlstrom)
• Preliminary fluvial incision model (Kirby)
• GIS database
• Compilation of existing incision data
  (Aslan,Karlstrom)
• Digitizing of Miocene basalts (Darling)
• Bibliographic archive (group)
• Arkansas - comparison to S. Platte (Leonard)
• Regional thermochron compilation - CP vs AA
  (Kelley)