Triassic Fluvial Systems, Colorado Plateau

Moenkopi Formation at Lees Ferry, Arizona

Chinle Formation at Paria (ghost town), Utah



Introduction

Triassic rocks on the Colorado Plateau comprise two well-known formations, the Lower and Middle Triassic Moenkopi Formation and the Upper Triassic Chinle Formation. Both consist of several members that vary in nature and distribution. Fluvial systems range from very large, perennial systems in both formations to ephemeral, small streams and associated dunes and sabkhas. Most streams flowed northwestward to northward from highlands south and east of the present Plateau (including mountains of Pangaea, the source of some of the really large rivers). Triassic rocks form some spectacular badlands including the beautiful Painted Desert.


Triassic Fluvial System graphics

The paleogeography of Triassic fluvial rocks on the Colorado Plateau is fairly well known. The following maps show moderately detailed hypothetical paleogeography for the Moenkopi and Chinle formations. The former is based on Blakey, Basham, and Cook (1993 -- see my list of refs above) and the later is based on Blakey and Gubitosa (1983). Most of the patterns and colors should be fairly intuitive so no separate key is provided.



  • Triassic Outcrops
  • Triassic Tectonic Settings
  • Moenkopi Stratigraphic Columns

    Triassic Fluvial Paleogeography

    Moenkopi Formation

  • Moenkopi 1
  • Moenkopi 2
  • Moenkopi 3
  • Moenkopi 4
  • Moenkopi 5
  • Moenkopi 6
  • Moenkopi 7
  • Moenkopi 8
  • Moenkopi 9
  • Moenkopi 10

    Chinle Formation

  • Chinle Shinarump
  • Chinle Monitor Butte
  • Chinle Moss Back
  • Chinle Petrified Forest
  • Chinle Owl Rock
  • Chinle Church Rock

    Outcrop Photos of Triassic Fluvial Rocks

    All photos were take by me and cannot be used for any commercial purposes withuot my permission.

  • Moenkopi and Chinle, Vermilion Cliffs
  • Moenkopi and Chinle, Paria
  • Moenkopi and Chinle, Orange Cliffs
  • Moenkopi near Winslow
  • Moenkopi near Cameron (type section)
  • Moenkopi near Cameron
  • Chinle (near type section) at Rock Point
  • Chinle at Lees Ferry
  • Chinle in Painted Desertl

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