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FT-02 Unconventional Reservoirs and Stratigraphy of the Southern Denver Basin: Graneros, Greenhorn, Carlile, and Niobrara Formations

Society for Sedimentary Geology (SEPM) - Rocky Mountain Section

Thursday, 30 September – Friday, 1 October 2021, 8:00 a.m.–9:55 a.m.  |  Pueblo, Colorado

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Course Content

This two-day trip will examine classic exposures of the Middle to Upper Cretaceous (Cenomanian to Campanian) strata of the southern Denver Basin near Pueblo, Colorado. Although the focus is on exceptional mudrock and tight sandstone outcrops of the Graneros, Greenhorn, Carlile, and Niobrara formations, currently of great interest for oil and gas exploration, lessons learned are directly applicable to other unconventional systems.

We will compare and contrast depositional and erosional events in these argillaceous, siliceous, and calcareous successions. Both small-scale depositional cycles as well as high-energy event beds are superimposed on large-scale transgressive-regressive successions. We also will observe the structural, stratigraphic, and sedimentological variability at the contact between the Greenhorn and Niobrara cycles. During our trip, we will view another significant feature: the Global Boundary Stratotype Section and Point (GSSP) for the Cenomanian-Turonian boundary. Finally, we will relate parameters important when evaluating unconventional plays – such as lithology, organic-carbon content, chronostratigraphic framework, and mechanical stratigraphy - to the underlying controls of sea-level change, orbital and climatic cycles, and oceanic oxygenation and circulation.


30 People
Ground transportation via air-conditioned bus
Lunches, snacks, and beverages in the field
One night single occupancy lodging in Pueblo, CO
Field trip guidebook

Physical Demands

We will be examining outcrops in a high desert setting. The weather during late September can range from dry and hot to cold, wet, and windy. Average daily highs are about 77°F (25°C), with lows about 45°F (7°C). T-shirts and shorts are sufficient if we have sunny days. However, if you are sun sensitive, a long-sleeve shirt in addition to a hat and sunscreen is a must. If a moist weather system moves in, we could encounter cool, cloudy days and rain. Bring along field pants, a rain jacket, and a sweater or sweatshirt that you can layer as needed.

The physical demands for this trip are MODERATE. We will be examining mudrock and sandstone exposures along hillsides, road cuts, and railroad tracks. Some outcrops have unstable footing, so hiking boots or low-cut hiking shoes are necessary (tennis shoes or open-toed sandals will not be allowed). You must break-in your boots beforehand to prevent blisters. Outcrops are at elevations between 3900 and 6000 ft (1300 and 2000m). The longest walk is approximately 2.5 miles (4 km) along a gravel road. Shorter walks will be along railroad tracks.

Our bus will have a toilet, and there are restrooms at some of our stops. However, we will be some distance from these facilities at a couple locations; bushes or gullies may provide the only cover for a bathroom break.

Items to Bring

If you have a hand lens, definitely bring it. Most grains in mudrocks are below the resolution of the human eye. Yet you can observe diverse sedimentologic and biogenic features with a hand lens. Although beverages will be provided, please bring your own water bottle. Other items to bring: pencil and eraser, small backpack (a must for carrying your water, jacket, and camera). Some stops will be in city and state parks, where a rock hammer is not allowed. At other localities you will be able to use a rock hammer; however, you also must use safety glasses if you plan to break rocks to view a fresh surface.

Here is the list of suggested items to bring:

  1. Sunscreen
  2. Sunglasses
  3. Raincoat or parka
  4. Hat/visor
  5. T-shirts and at least one long-sleeve shirt
  6. Light sweater, sweatshirt, or light jacket
  7. Shorts and long field pants
  8. Hiking boots
  9. Feld notebook
  10. Pencils and eraser
  11. Hand lens
  12. Small backpack
  13. Camera
  14. Water bottle/ canteen
  15. Insect repellent
  16. Rock hammer AND safety glasses


FT-02 Unconventional Reservoirs and Stratigraphy of the Southern Denver Basin:  Graneros, Greenhorn, Carlile, and Niobrara Formations
Pueblo, CO
Pueblo, Colorado
United States