New Mexico Geological Society
Fall Field Conference Guidebook – 68
The Geology of the Ouray-Silverton Area


Karl E. Karlstrom, David A. Gonzales, Matthew J. Zimmerer, Matthew Heizler, and Dana S. Ulmer-Scholle, [editors]
2017, 219 pages.

The 2017 NMGS Fall Field Conference examines the geologic history exposed in the Ouray-Silverton area of southwestern Colorado. The diverse and extensive geologic record in this area reveals events that span nearly 2 billion years. Many aspects of the geologic record exposed here are similar to northern New Mexico, such that "across the border" comparisons are important for understanding regional geology. Past NMGS field conferences to the western San Juan Mountains were held in 1957 and 1968. This 2017 conference serves as a retrospective of geologic advances over this timeframe and a snapshot of future research directions. Proterozoic basement in the San Juan Mountains include 1.8-1.7 Ga metamorphic and igneous rocks of the Yavapai province, and the overlying Uncompahgre Group, both of which may have correlatives in northern New Mexico. Paleozoic and Mesozoic stratigraphic units of the San Juan Mountains are uplifted to 3-km elevations in a dome-shaped uplift that borders the northern San Juan basin where correlative units are as much as 3 km below sea level. In the Oligocene, caldera-forming rhyolite and dacite ignimbrite eruptions of the San Juan Volcanic Field formed a volcanic highland composed of an extensive volcaniclastic apron that extended across northern New Mexico. Young (post-15 Ma) uplift and magmatism in the San Juan Mountains continues to shape the topography. World class ore deposits of southwestern Colorado reflect the same range in ages observed in the uplift and magmatic history with Laramide, mid-Tertiary, and post-15 Ma components. Quaternary geomorphology involves glacial records and deep incision along the Animas and Uncompahgre rivers. TheSan Juan Mountains are the headwaters for radial rivers, the Rio Grande, Rio Chama, Rio San Juan, and Rio Dolores systems, and snowpack variations dramatically influence surface water supply for the Four Corners region. Human history involves early native populations, historic mining rushes, and present-day skiing and recreation communities.

There are two versions of this guidebook available, the complete guidebook (219 pages), and a version with just the road logs that is spiral bound (82 pages).

ISBN: 978-1-58546-106-6

Softcover: $65.00 Buy Now
Softcover: $19.95 Buy Now
Contains road logs and mini-papers only, spiral bound.

Table of Contents:

Note —Downloads of the papers below are only available to current members (you must login first). Road logs mini-papers, maps, and other sections are only available in print.

  1. Day 0 Pre-Trip Hiking Log: Molas Lake to the Animas River and Train Ride on the Durango-Silverton Railroad to Silverton
    — K.E. Karlstrom and D.A. Gonzales, pp. 1-11.
  2. Day 1 Hiking Log: Ouray Perimeter Trail
    — D.A. Gonzales, K.E. Karlstom, L. Crossey, M. Heizler, and S.G. Lucas, pp. 11-23. [SUMMARY]
  3. Day 2 Road Log from Ouray to South of Animas Forks Via Silverton: Geology Along the Million Dollar Highway and of the Western San Juan Calderas
    — M.J. Zimmerer, D.A. Gonzales, and K.E. Karlstrom, pp. 23-46. [SUMMARY]
  4. Day 3A Road Log: From Ouray to Rico Hot Springs of the San Juan Region
    — J. Hrncir, B. Holt, D.A. Gonzales, A. Aslan, K.E. Karlstrom, L. Crossey, and M. Heizler, pp. 47-59. [SUMMARY]
  5. Day 3B Road Log: Gold King Mine Release and Environmental Concerns
    — J.M. Blake and S. Timmons, pp. 59-67. [SUMMARY]
  6. Papers:

    Note — To download papers from this guidebook, current members must login first.

  7. 40Ar/39Ar age constraints on the deposition and metamorphism of the Uncompahgre Group, southwestern Colorado
    — K.E. Karlstrom, D.A. Gonzales, M. Heizler, and A. Zinnser, pp. 83-90. [ABSTRACT] Supplemental Data:
  8. A review and revision of Late Mesozoic to Cenozoic pluton chronology in the Rico Mountains, southwestern Colorado
    — D.A. Gonzales, pp. 91-96. [ABSTRACT] Supplemental Data:
  9. Thermal and structural history of Paleozoic and Proterozoic rocks in the vicinity of Molas Pass, northern Needle Mountains, southwestern Colorado
    — S. A. Kelley and Karlstrom K.E., pp. 97-102. [ABSTRACT] Supplemental Data:
  10. Geochemical and geochronological characterization of Grand Mesa Volcanic Field, western Colorado
    — R. Cole, A. Stork, W. Hood, and M. Heizler, pp. 103-113. [ABSTRACT] Supplemental Data:
  11. An improved new age for the C33n-C32r paleomagnetic reversal, San Juan Basin, NW New Mexico and SW Colorado
    — J.E. Fassett and M.T. Heizler, pp. 115-121. [ABSTRACT] Supplemental Data:
  12. Heavy mineral, beach-placer sandstone deposits at Apache Mesa, Jicarilla Apache Reservation, Rio Arriba County, New Mexico
    — V.T. McLemore, pp. 123-132. [ABSTRACT] Supplemental Data:
  13. An overview of the mineral deposits of the Red Mountain mining district, San Juan Mountains, Colorado
    — D.A. Gonzales and R.A. Larson, pp. 133-140. [ABSTRACT]
  14. New insight into the history of clastic dikes in the western San Juan Mountains, southwestern Colorado
    — D.A. Gonzales and J.L. Koch, pp. 141-147. [ABSTRACT]
  15. Triassic-Jurassic stratigraphy in southwestern Colorado
    — S.G. Lucas, pp. 149-158. [ABSTRACT]
  16. Facies changes across a deforming salt shoulder, Chinle Formation, Gypsum Valley, Colorado
    — E.E. Heness, J. McFarland, R. Langford, and K. Giles, pp. 159-167. [ABSTRACT]
  17. Laramide and Cenozoic structural and paleotopographic history of the Ouray area and the northwestern flank of the San Juan Mountains, Colorado
    — T.E. Ewing, pp. 169-178. [ABSTRACT]
  18. New age constraints on Late Pleistocene glacial outwash deposits near Ridgway, Colorado, northern San Juan Mountains
    — D. Jarrin, A. Aslan, S. Mahan, and P.R. Hanson, pp. 179-186. [ABSTRACT]
  19. Geomorphic characteristics of fens in the San Juan Mountains, Colorado
    — K. Jeon, J.R. Giardino, and B.K. M. Gonzalez, pp. 187-194. [ABSTRACT]
  20. Glaciations of the San Juan Mountains: A review of work since Atwood and Mather
    — B. Johnson, M. Gillam, and J. Beeton, pp. 195-204. [ABSTRACT]
  21. Rock glaciers in the San Juan Mountains
    — B. Johnson, pp. 205-208. [ABSTRACT]
  22. Analysis of the Impact of Changing Weather Phenomena on the Timing and Discharge of the Uncompahgre, San Miguel, and Animas Rivers, Colorado
    — K.A. Kelkar, J.R. Giardino, J. Vitek, and G. Gamache, pp. 209-217. [ABSTRACT]