1. The Wyoming Craton is no longer a craton Part I
Suzan van der Lee
Craton = lithosphere with long-term stability

2. 1997:
2005:

3. IRIS EMC

4. IRIS EMC

5. IRIS EMC

6. IRIS EMC

7. IRIS EMC

8. Heather Bedle and Suzan van der Lee
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unpublished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 Bedle & Van der Lee, unpublished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 Bedle & Van der Lee, unpublished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. Trevor Bollmann Brad Sageman, Craig Jones Suzan van der Lee
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
Green circles: volcanism within the time period
Blue dashed line: Sevier front (line of zero sedimentation)

16. WIB: Cumulative depocenters not significantly different from era depocenters.
Replaces hidden slide 15

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

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

19. Add shapes of flat slab segment
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 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?)