Congratulations to CU TRaIL graduate student Josh Johnson for successfully defending his M.Sc. thesis entitled “Inverted” zircon and apatite (U-Th)/He dates and interpretation of high-damage zircon from the Southern Rocky Mountains, Front Range, Colorado. After defending, Josh is spending some time doing geoscience outreach in a National Park before deciding what to do with his recently acquired thermochronology skills.
CU TRaIL super-alum Alexis Ault, along with co-authors Becky Flowers and Sam Bowring, recently published a new paper in Earth and Planetary Science Letters detailing their work using thermochronology from cratons, in concert with geologic constraints, to investigate the long history of burial and unroofing experienced by these regions.
Ault, A.K., Flowers, R.M., and Bowring, S.A., 2015, Synchroneity of cratonic burial phases and gaps in the kimberlite record: Episodic magmatism or preservational bias?: Earth and Planetary Science Letters, v. 410, p. 97-104.
A variety of models are used to explain an apparent episodicity in kimberlite emplacement. Implicit in these models is the assumption that the preserved kimberlite record is largely complete. However, some cratons now mostly devoid of Phanerozoic cover underwent substantial Phanerozoic burial and erosion episodes that should be considered when evaluating models for global kimberlite distributions. Here we show a broad temporal coincidence between regional burial phases inferred from thermochronology and gaps in the kimberlite record in the Slave craton, Superior craton, and cratonic western Australia. A similar pattern exists in the Kaapvaal craton, although its magmatic, deposition, and erosion history differs in key ways from the other localities. One explanation for these observations is that there is a common cause of cratonic subsidence and suppression of kimberlite magmatism. Another possibility is that some…
CU TRaIL Ph.D. candidate Jess Stanley, along with co-authors Becky Flowers and David Bell recently published her most recent work in G3, using (U-Th)/He thermochronology to understand patterns of erosion and topographic change across the southern African Plateau.
Stanley, J.R., Flowers, R.M., and Bell, D.R., 2015, Erosion patterns and mantle sources of topographic change across the southern African Plateau derived from the shallow and deep records of kimberlites, Geochem. Geophys. Geosyst. v. 16, doi:10.1002/2015GC005969.
Flow in the sublithospheric mantle is increasingly invoked as a mechanism to explain both modern and past surface topography, but the importance of this phenomenon and its influence at different localities are debated. Southern Africa is an elevated continental shield proposed to represent dynamically supported topography. However, this region is also characterized by a complex lithospheric architecture variably affected by Cretaceous heating, thinning, and metasomatic alteration. We used apatite (U-Th)/He thermochronometry on 15 Cretaceous kimberlites from an ∼600 km long transect across the Kaapvaal Craton, combined with information from xenoliths in these pipes, to determine the plateau interior erosion history. The goal was to determine the relationships with lithospheric modification patterns and thereby better isolate the sublithospheric contribution to elevation. The results document a wave of erosion from west to east across the craton from…
CU TRaIL science was again well-represented at meetings across the country in 2015 with presentations by a whole range of TRaILers, from senior scientists to undergraduate interns. Check out the newest science, hot off the Alphachron!
Flowers, R.M., Arrowsmith, R., Metcalf, J.R., Rittenour, T., Schoene, B.S., Hole, J., Pavlis, T., Wagner, L., Whimeyer, S., and Williams, M.L., 2015, Geology, Geochronology, and EarthScope: The EarthScope AGeS program and a new idea for a 4D-Earth initiative: Invited, Fall AGU meeting, San Francisco, CA, December 2015.
Stanley, J.R. and Flowers, R.M., 2015, Dating kimberlite eruption and erosion phases using perovskite, zircon, and apatite (U-Th)/He geochronology to link cratonic lithosphere evolution and surface processes: Fall AGU meeting, San Francisco, CA, December 2015.
Collett, C., Duvall, A., Flowers, R.M., Tucker, G., 2015, Exhumation history of an oblique plate boundary: Investigating Kaikoura mountain-building within the Marlborough Fault System, NE South Island, New Zealand: Fall AGU meeting, San Francisco, CA, December 2015.
Lease, R., Haeussler, P., Metcalf, J., O’Sullivan, P.O., 2015, Accelerated erosion of high-latitude glaciated terrain in Alaska since 3-4 Ma: Fall AGU meeting, San Francisco, CA, December 2015.
Baughman, J.*, Flowers, R.M., Dhansay, T., Metcalf, J.R., Stoner, R.**, 2015, Influence of radiation damage on titanite (U-Th)/He dates from the Kaapvaal craton, southern Africa: National GSA meeting, Baltimore, MD, November…
Undergraduate RESESS intern Wesley Weisberg, who worked in the TRaIL facility during the summer of 2014, has just been awarded a GSA Rocky Mountain Section Undergraduate Research Grant. These funds will be used so that Wesley can continue his work on the project and visit the TRaIL this spring. Wes’s project focuses on using (U-Th)/He thermochronology to understand the evolution of the Wet Mountains in Colorado.
2014 has been a busy year for CU TRaIL science. Becky, Jim, and all of the students have presented their research at multiple meetings. See for yourself, CU TRaIL people are bolded.
Baughman, J., Flowers, R.M., and Dhansay, T., 2014, Stability of the Kaapvaal craton from titanite (U-Th)/He thermochronology and the strong influence of radiation damage on this underutilized thermochronometer: Fall AGU meeting, San Francisco, CA, December 2014.
Johnson, J.E., Flowers, R.M., Mahan, K.H., Baird, G.B., Metcalf, J.R. 2014, Repeated intracontinental tectonism in the Colorado Front Range: Filling critical gaps in thermal histories with titanite and zircon (U-Th)/He thermochronology: National GSA meeting, Vancouver, Canada, October 2014.
Johnson, J.E., Liefert, D.L., Flowers, R.M., 2014, Understanding our spectacular mountain landscapes: A helium thermochronology study in Rocky Mountain National Park: National GSA meeting, Vancouver, Canada, October 2014.
Landman, R.L., Rosenau, N.A., and Flowers, R.M., 2014, Constraining thermal histories in marine carbonates and black shales: A pilot conodont (U-Th)/He thermochronometry study in the Illinois basin: AAPG, Houston, TX, April 2014.
Landman, R.L., Flowers, R.M., Rosenau, N., Metcalf, J., and Powell, J., 2014,
Constraining thermal histories in carbonates and marine shales: exploring the conodont AHe thermochronometer: Thermo2014, 14th International Conference on Thermochronology, Chamonix, France, September 2014.
*Stanley, J.R., Flowers, R.M.,…
2013 saw two thermochronology short courses led by CU TRaIL personnel. In August, Becky Flowers and Jess Stanley led a 2-day course in Port Elizabeth, South Africa for African students and post-docs as part of the Africa Earth Observatory Network (AEON).
In October, Becky Flowers and Jim Metcalf led a one-day course on He thermochronology in conjunction with the 2013 GSA national meeting. In addition to talks by Becky and Jim highlighting the fundamentals of He thermochronology, the course also included a HeFTy tutorial, lab tour, and 3 invited talks by thermochronology specialists Professor Todd Ehlers (Universität Tübingen), Dr. Joe Colgan (USGS), and Dr. Desmond Patterson (ASI – UT Austin). The course was held in the Benson Earth Sciences Building at CU-Boulder, allowing participants to visit the CU TRaIL lab and see the facilities.
Both of the short courses were fantastic, and included a wide range of participants. We hope to lead more of these in the future, and have been encouraged by the feedback of the participants.