Workshop & FIELD TRIPS

WORKSHOP

Optech Users Workshop with Emphasis on Fracture Network Analysis.
Canceled.

FIELD TRIPS

1. The Geology and WPX Energy’s Development of the Mesaverde Tight-Gas Petroleum System, Piceance Basin, Colorado, USA.
Canceled.
Elk Mountains
Elk Mountains
2. From Ignimbrite to Batholith, NE San Juan Mountains.
Tues., 14 May. US$90. Max: 19.
Peter Lipman, USGS, plipmanatusgs.gov.
The northeastern San Juan Mountains, the least-studied portion of this well-known volcanic region, are the site of several newly identified and/or reinterpreted ignimbrite caldera systems that overlie a large geophysically imaged granitic batholith. We will (1) view features of the Cochetopa Park caldera, presenting evidence that no large explosive eruptions vented from this morphologically beautifully preserved caldera—rather, Cochetopa Park subsided passively as the >500 km3 Nelson Mountain Tuff vented at 26.9 Ma from an "underfit" caldera 30 km to the SW; (2) traverse the recently recognized North Pass caldera, source of the 32 Ma Saguache Creek Tuff, a regionally distinctive crystal-poor alkalic rhyolite that bridges an apparent gap in the southwestward migration from older explosive volcanism in central Colorado to the culminating locus of Tertiary volcanism in the central San Juan region; and (3) focus on the 33.2 Ma Bonanza caldera, characterized by an array of exceptional features, including exposed levels from near-original rim down through caldera floor, 3.5-km thick caldera-filling ignimbrite and lavas, exceptionally steep resurgent dome, and associated granitic intrusions. New Ar-Ar single-crystal age determinations are critical to these reinterpretations.
3. Quaternary Glacial and Climate History of the Taylor River Basin, Gunnison County, Colorado.
Sat., 18 May. US$75. Max: 20.
Keith Brugger, University of Minnesota Morris, bruggekaatmorris.umn.edu.
This one-day field trip is designed to highlight the glacial and climate history of the Taylor River basin. Particular attention will be given to relative-age criteria used to distinguish between moraines of different ages; cosmogenic ages of moraines from the last glacial maximum (LGM); mapping of ice extent during LGM; the nature or style of glaciation in the area; glacier reconstructions, equilibrium-line altitudes, and their paleoclimate significance; and a local Holocene climate proxy derived by lichenometric dating of rock glacier activity. In addition, several remaining "problems" within the drainage will be discussed.
4. Geology and Mineral Deposits of the Iron Hill (Powderhorn) Carbonatite-Alkaline Complex, Gunnison County, Colorado, USA.
Sat., 18 May. US$45. Max: 20.
Brad Van Gosen, USGS, bvangoseatusgs.gov; Kevin H. Mahan, University of Colorado Boulder, Kevin.Mahanatcolorado.edu.
Participants will spend the day exploring the Powderhorn–Iron Hill carbonatite and associated alkaline intrusives. There will be several short hikes to particular outcrops. Observations and discussion will center on the rock types, the petrology, and the history and potential as an economic mineral deposit (e.g., Ti, Nb, REEs, actinides).

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