Schedule 2024

Wednesday, 1/17: Overview of class, themes in Cordilleran history

• 17 January's overview figures (pdf, 14.2 Mb)

Friday, 1/19: Precambrian terranes, U-Pb dating, Sm-Nd model ages
Reading:

• slides from class
• sec. 10-3 and 10-4 of Turcotte and Schubert (10-1 and 10-2 are helpful). 
• Radiometric dating handout
• Ch. 1 of Baldridge is relevant
• Reed, J. C., Jr., T. T. Ball, G. L. Farmer, and W. B. Hamilton, A broader view, in Precambrian: Conterminous U. S., The Geology of North America, vol. C-2, edited by J. C. Reed, Jr. and others, pp. 614-622 (Farmer's section), Geol. Soc. Amer., Boulder, Colo., 1993

Wednesday, 1/24: Precambrian sediments, late pC rifting, possibly thermal subsidence material (likely bleeds into Friday)

• Detrital zircon handout (draft, really, at present)
• slides for class (pC seds)
• Gehrels, G., 2014, Detrital Zircon U-Pb Geochronology Applied to Tectonics: Annual Review of Earth and Planetary Sciences, Vol 42, v. 42, p. 127-149, doi: 10.1146/annurev-earth-050212-124012.
  • (for reference, an example of double dating, in this case with Lu-Hf: Gehrels, G., and Pecha, M., 2014, Detrital zircon U-Pb geochronology and Hf isotope geochemistry of Paleozoic and Triassic passive margin strata of western North America: Geosphere, doi: 10.1130/GES00889.1).
• Yonkee, W. A., Dehler, C. D., Link, P. K., Balgord, E. A., Keeley, J. A., Hayes, D. S., Wells, M. L., Fanning, C. M., and Johnston, S. M., 2014, Tectono-stratigraphic framework of Neoproterozoic to Cambrian strata, west-central U.S.: Protracted rifting, glaciation, and evolution of the North American Cordilleran margin: Earth-Science Reviews, v. 136, no. C, p. 59-95, doi: 10.1016/j.earscirev.2014.05.004.

Friday, 1/26: Late pC rifting, thermal subsidence. Goals: Know the relationships in space and time between lithospheric thinning and elevation and sedimentation; be able to interpret a tectonic subsidence curve and know how this differs from a stratigraphic thickness curve; be aware of the impact on North American lithosphere from the terminal rifting event, be able to articulate the relationship between rifting and the passive margin (miogeoclinal) sedimentary rocks.

• Notes on thermal subsidence and backstripping
• Images used in class
• Turcotte and Schubert, sec. 4-15, 4-16, 4-23, 4-25, last is most relevant, earlier readings provide background. [An alternative that is more compact and comes from a more geologic point of view is in Stüwe's text, sections 6.1.3 & 6.1.4; this also includes a description of how backstripping works missing from Turcotte and Schubert] 
• Bond, G. C., and M. A. Kominz, Construction of tectonic subsidence curves for the early Paleozoic miogeocline, southern Canadian Rocky Mountains; implications for subsidence mechanisms, age of breakup, and crustal thinning, Geological Society of America Bulletin, 95, (2), 155-173, 1984.  
• Chs. 2 and 3 of Baldridge are relevant

Wednesday 1/31: Ancestral Rockies. Goals: Identify uplifts and basins using geologic maps. Identify tectonic features like uplifts and basins from likely variations in facies (sedimentary rock characteristics indicative of the depositional environment, e.g. fluvial conglomerates indicating rapidly moving rivers and stream fairly heavily laden with sediment).

• Figures in class from 1/31 and 2/2

Friday, 2/2: Homework 1 due. Ancestral Rockies. Goals: Recognize differences in basin geometry and subsidence depending on tectonic environment. Able to use plate flexure to interpret geology.

• Xie, X., & Heller, P. (2009). Plate tectonics and basin subsidence history. Geological Society of America Bulletin, 121(1/2), 55–64. doi:10.1130/B26398.1
• Flexure notes or equivalent sections in Turcotte and Schubert, 3-9, 3-13, 3-14 to 3-18

Wednesday 2/7: Antler orogeny. Goals: Apply elastic plate theory to a mysterious orogeny. Consider novel ideas for this orogeny. Examine detrital zircon observations for the origin of the allocthon. (So no new tools per se, but a better grouding in the use of some).

• Read: Burchfiel, B. C., and L. H. Royden, Antler Orogeny: A Mediterranean-type orogeny, Geology, 19, (1), 66-69, doi 10.1130/0091-7613(1991)019%3C0066:AOAMTO%3E2.3.CO;2, 1991. This is a compact paper that points out a lot of the strange aspects of the Antler orogeny. Note the appeal to modern analogs.
• This is probably also worth your time (and is short but much denser): Cashman, P. H., and Sturmer, D. M., 2023, The Antler orogeny reconsidered and implications for late Paleozoic tectonics of western Laurentia: Geology, 51 (6), p. 543-548, doi: 10.1130/G50977.1.
• slides from class

Friday 2/9: Antler orogeny conclusion, truncation event. Goals: Consider novel ideas for this orogeny and try to determine compatibility with observations.

• (papers from Wednesday still relevant)
• Homework 2 will be distributed...

Wednesday, 2/14. Let's examine a paper closely for clues about the Roberts Mtn allocthon and a possible truncation event as well as some issues in detrital zircons...(so post meeting, some things you might want to take away: how do we identify concordent zircons for detrital work? What does lead loss do to zircon ages?

• Clemens-Knott, D., and Gevedon, M., 2023, Using discordant U-Pb zircon data to re-evaluate the El Paso terrane: Late Paleozoic tectonomagmatic evolution of east- central California (USA) and intense hydrothermal activity in the Jurassic Sierra Nevada arc: Geosphere, v. 19, no. 2, p. 531-557, doi: 10.1130/Ges02547.1.

Friday, 2/16. Sonoman orogeny. Yes, we're still messing with detrital zircons, but this is now starting to see arcs somewhere in northern Nevada. Just how exotic are things getting?

• Lawton, T. F., Cashman, P. H., Trexler Jr., J. H., and Taylor, W. J., 2017, The late Paleozoic Southwestern Laurentian Borderland: Geology, v. 45, no. 8, p. 675-678, doi: 10.1130/G39071.1.
• slides from class

Wednesday, 2/21. How exotic is it? We'll look at the zircon story for the Sonoma orogeny (and others) a bit to try and decide how believable different interpretations are. So the two papers below have very different views of the sources for some of those zircons, namely the northern Sierra and Klamath terranes. So you might skim these before class

• Colpron, M., and Nelson, J.L., 2009, A Palaeozoic Northwest Passage: incursion of Caledonian, Baltican and Siberian terranes into eastern Panthalassa, and the early evolution of the North American Cordillera, in Cawood, P.A. and Kröner, A. eds., Earth Accretionary Systems in Space and Time, Geological Society, London, Special Publications, v. 318, p. 273-307, doi: 10.1144/SP318.10.
• Attia, S., Paterson, S.R., Cao, W., Chapman, A.D., Saleeby, J., Dunne, G.C., Stevens, C.H., and Memeti, V., 2018, Late Paleozoic tectonic assembly of the Sierra Nevada prebatholithic framework and western Laurentian provenance links based on synthesized detrital zircon geochronology, in Tectonics, Sedimentary Basins, and Provenance: A Celebration of the Career of William R. Dickinson, Geological Society of America Special Paper, v. 540, p. 267–295, doi: 10.1130/2018.2540(12).
• Images used in class

Friday, 2/23. Details depend on Wednesday, but Snir Attia is talking about Sierran geology and Laurentia, which sounds a lot like an update on the paper from Wednesday, so hoping we'll eavesdrop on that talk starting at noon. Prior to the noon talk, we'll polish off the last little bits of the detrital zircon stuff and go over paleomagnetic work.

• Paleomag overview
• Slides from paleomag lecture

Wednesday, 2/28. Meet with Basil Tikoff (lunch) and attend or watch talk.

Friday, 3/1. Homework 3 due. Finish going over paleomag. Other details to come.

• Tikoff's paper that was the bulk of the talk: Tikoff, B., Housen, B. A., Maxson, J. A., Nelson, E. M., Trevino, S., Shipley, T. F., Whitmeyer, S. J., Williams, M. L., Kellett, D. A., and Tikoff, B., 2023, Hit-and-run model for Cretaceous–Paleogene tectonism along the western margin of Laurentia, Laurentia: Turning Points in the Evolution of a Continent: v. 220, Geological Society of America, p. 0, doi: 10.1130/2022.1220(32).
• Paleomag that Tikoff highlighted is in this paper Enkin, R. J., Mahoney, J. B., Baker, J., Riesterer, J., and Haskin, M. L., 2003, Deciphering shallow paleomagnetic inclinations: 2. Implications from Late Cretaceous strata overlapping the Insular/Intermontane Superterrane boundary in the southern Canadian Cordillera: Journal of Geophysical Research: Solid Earth, v. 108, no. B4, p. 1-19, doi: 10.1029/2002JB001983. We might look at this a bit [actually a 2006 paper is what he was alluding to, not online]
• Paleomag overview
• Slides from paleomag lecture

Wednesday, 3/6. Exotic terranes: how we know they exist (mainly last time), how we determine where they come from, and how we estimate when they arrive.

• Slides from class.

Friday, 3/8. Plate reconstructions. How do we know how two plates moved relative to one another. Hot spot vs. plate circuit vs. "deep time" reconstructions. HW 4 (paleomag).

• Plate reconstruction handout
• Images used in class
• A couple of papers extending plate reconstructions back into the early Mesozoic and beyond. Really reading in detail both is a big ask; instead you probably want to look to see what the criteria are being used. Merith et al. has a nicer presentation of the "how we built this"; Müller et al. addresses the problem of what to do when your plates are deforming.
  • Müller, R. D., Zahirovic, S., Williams, S. E., Cannon, J., Seton, M., Bower, D. J., Tetley, M. G., Heine, C., Le Breton, E., Liu, S., Russell, S. H. J., Yang, T., Leonard, J., and Gurnis, M., 2019, A Global Plate Model Including Lithospheric Deformation Along Major Rifts and Orogens Since the Triassic: Tectonics, v. 38, no. 6, p. 1884-1907, doi: 10.1029/2018TC005462.
    • Animations of this model (250 Ma on) can be found here.
  • Merdith, A. S., Williams, S. E., Collins, A. S., Tetley, M. G., Mulder, J. A., Blades, M. L., Young, A., Armistead, S. E., Cannon, J., Zahirovic, S., and Müller, R. D., 2021, Extending full-plate tectonic models into deep time: Linking the Neoproterozoic and the Phanerozoic: Earth-Science Reviews, v. 214, doi: 10.1016/j.earscirev.2020.103477.
  • And then there is the tomo-tectonic model Basil mentioned, should you want to go there: Clennett, E. J., Sigloch, K., Mihalynuk, M. G., Seton, M., Henderson, M. A., Hosseini, K., Mohammadzaheri, A., Johnston, S. T., and Müller, R. D., 2020, A Quantitative Tomotectonic Plate Reconstruction of Western North America and the Eastern Pacific Basin: Geochemistry, Geophysics, Geosystems, v. 20, no. 8, p. 25, doi: 10.1029/2020GC009117.
    • Their video (mp4, 15Mb) is online. (It is embedded in the Müller 2019 global model).

Wednesday, 3/13. Franciscan complex. What is a melange? How can we tell sedimentary from tectonics melanges, and why might we care? What do blueschists represent?

• Slides from lecture
• Take a look at this, keeping in mind the significance of melanges. Wakabayashi, J., 2021, Subduction and exhumation slip accommodation at depths of 10–80 km inferred from field geology of exhumed rocks: Evidence for temporal-spatial localization of slip, in Wakabayashi, J., and Dilek, Y., eds., Plate Tectonics, Ophiolites, and Societal Significance of Geology: A Celebration of the Career of Eldridge Moores: GSA Special Paper: v. 552: Boulder, Colorado, Geol. Soc. Amer., p. 257-296, doi: 10.1130/2021.2552(12).

Friday, 3/15: Snow day

Wednesday, 3/20, Class project discussion first. (We really need that settled). Fold-and-thrust belts. How and why do they develop as is usually observed? What is a "Coulomb wedge" and how does it help to understand fold-and-thrust belts.

• Coulomb wedge handout
• Turcotte and Schubert, section 8-6 (also Stüwe, pp. 294-298 1st ed, 308-315 (section 6.2.3) 2nd ed)
• Baldridge sections 6.6, 7.2
• application: DeCelles, P. G., and G. Mitra, History of the Sevier orogenic wedge in terms of critical taper models, Northeast Utah and Southwest Wyoming, Geological Society of America Bulletin, 107, 454-462, 1995
• Slides from class and movie of shovelling snow

Friday, 3/22: No meeting in person. Term project targets should be submitted. What are key observables related to the hit-and-run hypothesis? Some of these will be points the authors bring out, but some might be questions you might have about the implications of the model. Send in at least 2 possible targets for a term project.

• Tikoff, B., Housen, B. A., Maxson, J. A., Nelson, E. M., Trevino, S., and Shipley, T. F., 2023, Hit-and-run model for Cretaceous–Paleogene tectonism along the western margin of Laurentia, in Whitmeyer, S. J., Williams, M. L., Kellett, D. A., and Tikoff, B., eds., Laurentia: Turning Points in the Evolution of a Continent: Geol. Soc. Am. Memoir: v. 220: Boulder, Colo., Geological Society of America, p. 0, doi: 10.1130/2022.1220(32).
  • The original paper (citations to it might prove helpful in identifying papers making points that are still relevant): Maxson, J., and Tikoff, B., 1996, Hit-and-run collision model for the Laramide orogeny, western United States: Geology, v. 24, no. 11, p. 968-972.
• A relevant paper that might be of use: Trevino, S. F., and Tikoff, B., 2023, Two phases of Cretaceous dextral shearing recorded in the plutonic rocks of NW Nevada (USA): A tectonic link between intra-arc shearing in the Sierra Nevada and Idaho batholiths: Geosphere, v. 19, no. 6, p. 1539-1564, doi: 10.1130/Ges02682.1.

Wednesday, 4/3: Hinterland, paleobarometers and their interpretation. What is a geobarometer? What is necessary for it to work? What is the significance of changes in paleopressure?

• Hodges, K. V., and Walker, J. D., 1992, Extension in the Cretaceous Sevier Orogen, North-American Cordillera: Geological Society of America Bulletin, v. 104, no. 5, p. 560-569, doi: 10.1130/0016-7606(1992)104%3C0560:EITCSO%3E2.3.CO;2.
• Zuza, A. V., Levy, D. A., and Mulligan, S. R., 2022, Geologic field evidence for non-lithostatic overpressure recorded in the North American Cordillera hinterland, northeast Nevada: Geoscience Frontiers, v. 13, no. 2, 101099, doi: 10.1016/j.gsf.2020.10.006.
• Stuwe, section 7.2.1-7.4.1 (pp. 346-363) is a helpful reference on techniques
• Images from class.

Friday, 4/5: Revise/confirm term project topics. Arcs and "mohometry".

• For term project prep, please reread Tikoff et al. and read Cowan et al. which, despite age, should help to clarify elements of Baja-BC that are relevant for hit-and-run.
  • Tikoff, B., Housen, B. A., Maxson, J. A., Nelson, E. M., Trevino, S., and Shipley, T. F., 2023, Hit-and-run model for Cretaceous–Paleogene tectonism along the western margin of Laurentia, in Whitmeyer, S. J., Williams, M. L., Kellett, D. A., and Tikoff, B., eds., Laurentia: Turning Points in the Evolution of a Continent: Geol. Soc. Am. Memoir: v. 220: Boulder, Colo., Geological Society of America, p. 0, doi: 10.1130/2022.1220(32).
  • Cowan, D., Brandon, M., and Garver, J., 1997, Geologic tests of hypotheses for large coastwise displacements—A critique illustrated by the Baja British Columbia controversy:American Journal of Science, 297, p.117-173, 1997.
  • Reminder that the different research aids are described here.
• Reference for "Mohometry":
  • Luffi, P., and Ducea, M. N., 2022, Chemical Mohometry: Assessing Crustal Thickness of Ancient Orogens Using Geochemical and Isotopic Data: Reviews of Geophysics, v. 60, no. 2, e2021RG000753, doi: 10.1029/2021RG000753.

Wednesday, 4/10: Arcs & mohometry; fold methodology and limitations.where were arcs over time, and what is the significance of arc movement? Do arcs wax and wane, and if so, why? How might we know, and what biases are present? What (if any) connection exists between the arc and the foreland fold-and-thrust belt?

• Reference for "Mohometry":
  • Luffi, P., and Ducea, M. N., 2022, Chemical Mohometry: Assessing Crustal Thickness of Ancient Orogens Using Geochemical and Isotopic Data: Reviews of Geophysics, v. 60, no. 2, e2021RG000753, doi: 10.1029/2021RG000753.
• Images used in class for Mesozoic-Cenozoic magmatism, crustal thickness
• Images for Laramide structure intro (mainly Suppe-style fault-fold models)

Friday, 4/12: Structural style of Laramide, trishear fold models, paleostress. What geometrical models allow interpretation of basement-cored uplifts? How might we know the stress state during the Laramide? What is total shortening across the Laramide Rockies, and how does that vary between ranges? Was Laramide deformation one long event or several subevents?

• Stress inversion handout
• Images from class
• For Laramide structures: Erslev, E. A, Trishear fault-propagation folding, Geology, 19 (6) pp. 617-620, 1991.
• We might get to some dynamic topography discussion, in which case reviewing the dynamic topo handout would be helpful.

Wednesday, 4/17: Dynamic topography, basins, and Laramide hypotheses. How does dynamic pressure work? What is dynamic topography, and how might it be related to basins? Just how did sedimentation change from Sevier to Laramide time? Why is a flat slab attractive? What problems does it face? What alternatives are out there?

• The dynamic topo handout would be helpful.
• A nice overview of all the pieces to a Laramide model are in Bird, P., 1984, Laramide crustal thickening event in the Rocky Mountain foreland and Great Plains: Tectonics, v. 3, no. 7, p. 741-758, doi: 10.1029/TC003i007p00741.
• Images used in class (plus some for Friday)

Friday, 4/19: Shatsky Conjugate, Alternative models. How do we know there was a Shatsky conjugate? How can we decide where it was? How do we determine its effect on the surface? What should alternative models predict? What options are there?

• Please read and be ready to discuss: Liu, L., Gurnis, M., Seton, M., Saleeby, J., Müller, R. D., and Jackson, J. M., 2010, The role of oceanic plateau subduction in the Laramide orogeny: Nature Geoscience, v. 3, no. 4, p. 1-5, doi: 10.1038/ngeo829. Note there is a supplement that can be of some use.
• If you are curious, a recent paper with some challenges for the Shatsky story: Schwartz, J. J., Lackey, J. S., Miranda, E. A., Klepeis, K. A., Mora-Klepeis, G., Robles, F., and Bixler, J. D., 2023, Magmatic surge requires two-stage model for the Laramide orogeny: Nature Communications, v. 14, no. 1, 3841, doi: 10.1038/s41467-023-39473-7.
• Another resource. How much should we believe a specific seismic tomographic model? One thing you can do is compare a bunch of models...which would be daunting except that there are tools at IRIS that allow one to make these plots fairly easily. You might want to fist identify models relevant for your concerns (hit the "Earth Models" link, where models are listed by extent) and then, armed with the shorthand ID of the models of interest, you can make arbitrary cross sections, stacked sections, stacks of map views at different depths, etc.

Wednesday, 4/24: Paleoelevation. What approaches work for getting ancient elevations? What are the assumptions? What are the weaknesses? Focus will be on "Nevadaplano"; consider the differences in interpretations of these two papers and why they do differ:

• Lechler, A. R., Niemi, N. A., Hren, M. T., & Lohmann, K. C. (2013). Paleoelevation estimates for the northern and central proto-Basin and Range from carbonate clumped isotope thermometry. Tectonics, 32(3), 295–316.
• Snell, K. E., Koch, P. L., Druschke, P., Foreman, B. Z., & Eiler, J. M. (2014). High elevation of the “Nevadaplano” during the Late Cretaceous. Earth and Planetary Science Letters, 386(C), 52–63.
• This week's colloquium touches on related issues, so for instance Kelson, J. R., Petersen, S. V., Niemi, N. A., Passey, B. H., and Curley, A. N., 2022, Looking upstream with clumped and triple oxygen isotopes of estuarine oyster shells in the early Eocene of California, USA: Geology, v. 50, no. 7, p. 755-759, doi: 10.1130/G49634.1 uses datasets based on work of the speaker this week, like Wostbrock, J. A. G., Cano, E. J., and Sharp, Z. D., 2020, An internally consistent triple oxygen isotope calibration of standards for silicates, carbonates and air relative to VSMOW2 and SLAP2: Chemical Geology, v. 533, 119432, doi: 10.1016/j.chemgeo.2019.119432.
• Images used in class
• Paleoelevation handout

Friday, 4/26: Gravitational potential energy, Basin and Range extension and Core Complexes. What are the sources of stress necessary to drive deformation? How does lithospheric structure affect those stresses? What is a core complex, and how might they form? What is the relationship between Basin and Range extension and the evolution of magmatism?

• Forces acting on the lithosphere (handout) (might note new paleoelevation handout covering some of Wednesday's class material)
• Turcotte and Schubert, pp. 226-229 (section 6-1, 6-2); (Baldridge sec. 8.4)
• Buck, W. R., Modes of continental lithospheric extension, J. Geophys. Res., 96, 20,161-20,178, doi: 10.1029/91JB01485,1991.
• Images used in class

Wednesday, 5/1: Term project presentations. Please send whatever PowerPoint/Keynote you intend to show prior to class so they can all be on one computer. Everybody gets 15 minutes, but aim for less so there can be some Q and A and discussion.

GEOL5690 home | C. H. Jones | CIRES | Dept. of Geological Sciences | Univ. of Colorado at Boulder

Last modified at April 26, 2024 5:47 PM