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Geological Features of Mariscal Canyon in Big Bend National Park

Discover the unique geological structures of Mariscal Canyon in Big Bend National Park, including contractional and extensional deformations, rhyolite ignimbrites, stratigraphy, faults, and more. Explore the diverse formations and formations in this stunning canyon.

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Geological Features of Mariscal Canyon in Big Bend National Park

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  1. Mariscal Canyon, Southernmost Big Bend National Park: Contractional and Extensional Deformation and A Recently Exhumed Rhyolite Ignimbrite Patricia Wood Dickerson South-Central GSA, March 2012

  2. Mariscal Canyon — Talley to Solis

  3. Lower Cretaceous Stratigraphy Santa Elena - massive limestone cliff-former Sue Peaks - shale & thin limestone slope-former Del Carmen - massive limestone cliff-former Confirmed exposures of Kdc and Ksp in Mariscal Mountain. Ksp somewhat thinner than in Sierra del Carmen, Santa Elena Canyon.

  4. WSW-Striking Fault & Thrust Detail

  5. Rio Grande Flooding, September 2008 Boquillas Hot Springs - note bathhouse

  6. Thrust Fault in Central Canyon North riverbank – exhumed by flooding Ksp and Kse are thrust, overturned to E Thrust is cut by N-striking normal fault; thin-bedded, overturned Ksp against massive, near-horizontal Kse; thick breccia carapace Ksp is oldest unit at river level on N bank

  7. Thrust Fault & Normal Fault, Central Canyon River flows in WNW-striking normal fault that cuts thrust. South bank is upthrown, exposing thrusted Kdc, Ksp & Kse. Kdc is not present on north riverbank and was not seen east of this reach of the Canyon.

  8. Cross Canyon Detail

  9. Cross Canyon - View NW Kse rolling over along thrust crest, dips to ~30° E Kbo folded to east of thrust

  10. Newly Exhumed Ignimbrite (gray, foreground) • Densely welded rhyolite tuff • Dips 25 degrees SSW • Discordant with respect to • deformed Cretaceous strata • N contact buried beneath sand • and gravel; E, S & W contacts • submerged • Probable remnant of more • extensive deposit, preserved • in depression in K rocks • Foundered into a solution- • collapse cavity? (common on • Mariscal Mt.) • Let down due to undercutting • by the river & removal of • fractured, less resistant K rock?

  11. Solution Collapse Features – Foundered Rhyolite Sill, NE Flank of Mariscal Mt. (Dickerson et al., 2010, BEG Misc. Map 48)

  12. Cross Canyon — Fold in Footwall of N-Striking Thrust Kbu in fold flank Kbu and folded Kbo

  13. Slickenside Camp — Flower Structure

  14. Slickensided Fault Wall, Flower Structure L-L fault, striae rake 40° SE Fault breccia at striated wall

  15. Eastern Flower Structure Fault Kse dips 11º SW east of fault, 21º WSW on west Contractional fault at cliff base Undulating shear planes 

  16. Western Flower Structure Fault Variable S and W dips on slabs between shears 1 or 2 m vertical offsets Contractional fault at lower left Horizontal Kse approaching flower structure from W 

  17. Flower Structure Diagram (Goetz in Goetz & Dickerson, 1985)

  18. Eastern Range-Front Fault Kbo downdropped against Kse on normal fault Kse dips 12° E, Kbo dips 14 ° E

  19. Mariscal Canyon – more to explore… Thanks to Commander & Crew: Marcos Paredes, NPS Jim Bones Mary Bridges Bones

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