1 / 31

The Wyoming Craton is no longer a craton Part I

This study explores the relationship between plate flexure, subsidence, and volcanic activity in Wyoming during the late Cretaceous period. It investigates the effect of crustal material beneath the basins on the width and depth of the Western Interior Basin (WIB) and analyzes the presence of the flat Farallon slab and oceanic plateau beneath Wyoming. The study also models tomography and sedimentation to understand the placement of segments during this time.

berniceg
Download Presentation

The Wyoming Craton is no longer a craton Part I

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Wyoming Cratonis no longer a cratonPart I Suzan van der Lee

  2. 1997: 2005:

  3. IRIS EMC

  4. IRIS EMC

  5. IRIS EMC

  6. IRIS EMC

  7. IRIS EMC

  8. Wyoming, Part II Heather Bedle and Suzan van der Lee

  9. Bedle & Van der Lee, includes early USArray data from W US, unpublished

  10. Bedle & Van der Lee, unpublished

  11. Bedle & Van der Lee, unpublished

  12. Wyoming, Part III Trevor Bollmann Brad Sageman, Craig Jones Suzan van der Lee

  13. Motivation • Overriding plate can flex and form foredeep. • WIB is a textbook flexural basin until it widens excessively. • Flat Farallon “sucked” down a wide section of overriding plate (WIB).

  14. Questions • Does WIB widening coincide with a change in the pattern of volcanism? • Does the crustal material beneath the basins have an effect on the depth/width of the WIB? • Did the point of maximum subsidence stay constant or move with the Farallon plate over time? • Was the flat Farallon slab beneath the WIB during its widening? • Was a particular oceanic plateau beneath Wyoming when the WIB widened? • Model sub-WIB slab fragments forwards in time and compare to tomography. • Model tomography backwards in time to find segment placement in late Cretaceous

  15. Sedimentation vs. Pattern of Volcanism Cenomanian Turonian Coniacian-Santonian Campanian I Campanian II Maastrichtian

  16. WIB: Cumulative depocenters not significantly different from era depocenters.

  17. Shatsky Rise Conjugate (SRC) Backwards modeling Hess Rise Conjugate (HRC)

  18. SRC Add shapes of flat slab segment or oceanic plateau SRC tracks with Flat Slab box SRC tracks with Oceanic Plateau box

  19. SRC Add shapes of flat slab segment or oceanic plateau HRC tracks with Flat Slab box HRC tracks with Oceanic Plateau box

  20. Turonian Slab Locations with Isopach Flat Slab Oceanic Plateau

  21. Coniacian-Santonian Slab Locations with Isopach Flat Slab Oceanic Plateau

  22. Campanian I Slab Locations with Isopach Flat Slab Oceanic Plateau

  23. Campanian II Slab Locations with Isopach Flat Slab Oceanic Plateau

  24. Maastrictian Slab Locations with Isopach Flat Slab Oceanic Plateau

  25. Forwards modeling Campanian I Depo-center 80 m.y.a Campanian II Depo-center 75 m.y.a Point of Maximum Deposition in Campanian I Point of Maximum Deposition in Campanian I

  26. Campanian I Depo-center Forwards modeling Campanian II Depo-center

  27. S362ANI+M (Vs km/s) - 1200 km depth Location of modeled slab *This model is in velocity, not velocity difference from the background model like the previous examples.

  28. GYPSUM (dVs %) - 1200 km depth Location of modeled slab

  29. Conclusions • The point of maximum subsidence and deposition did not move significantly during the late Cretaceous. • There are slab fragments that were beneath the basin at the right time to interact with the crust and deepen the basin. • The Seton et al. 2012 model is a better fit to the basins in the isopach • A Flat Slab window sized slab seems to be a better spatial match to the isopachs • Flat-slab fragments would have been effective at hydrating/metasomatizing the Wyoming lithosphere from below.

  30. Further Work Needed (From others) • Recreate the regional isopachs using all available data • The last were completed 20 years ago • 3-D crustal flexural modeling • Some 2-D modeling has been completed but 3-D with crustal properties from different provinces could be useful • Plotting the reconstructed slab locations on a palinspastic reconstruction of North America • Would change the locations shown earlier. How much is unclear.

  31. References for workshop • Bedle, PhD thesis • Carlson 2014 • P. V. Doubrovine, B. Steinberger, and T. H. Torsvik. Absolute plate motions in a reference frame defined by moving hot spots in the Pacific, Atlantic, and Indian oceans. Journal of Geophysical Research: Solid Earth, 117(B9), 2012. • R. Dietmar Müller, J.-Y. Royer, and L. A. Lawver. Revised plate motions relative to the hotspots from combined atlantic and indian ocean hotspot tracks. Geology, 21:275, 1993. • Hoffmann 1988 • Kirschbaum and Rogers • Porter et al. • M. Seton, R. Müller, S. Zahirovic, C. Gaina, T. Torsvik, G. Shephard, A. Talsma, M. Gurnis, M. Turner, S. Maus, et al. Global continental and ocean basin reconstructions since 200Ma. Earth-Science Reviews, 113(3):212–270, 2012. • VdLee and Nolet JGR 1997 • Gypsum • Sigloch? (Shatsky Rise?)

More Related