Congratulations to (now former) SSR graduate student Sebastian Kaempfe on successfully defending his dissertation in May 2022 and officially graduating from the program and obtaining his Ph.D.! Sebastian (who is originally from Punta Arenas, Chile) and I first met back in 2014, when he approached us asking if he could be a field assistant for the Chile Slope Systems research group. Sebastian joined us each February-March the next couple of field seasons, both helping us out and learning about the work we were doing. The result of this interaction was Sebastian coming here to Blacksburg, VA in January 2016 to start a Ph.D. and develop research projects on the geology of a region he grew up exploring.
Sebastian’s dissertation is titled Multi-scale deep-marine stratigraphic expressions in the Cretaceous Magallanes Basin, Chile: Implications for depositional architecture and basin evolution, comprising three chapters that span a range of scales, from detailed (bed-scale) sedimentology to basin-scale paleogeography. All three projects involved extensive field work in the Cerro Toro and Tres Pasos Formations of southern Chile:
(1) The Stratigraphic Expression of Early Channel-fill Deposits During the Evolution of Submarine Slope Channels in the Upper Cretaceous Tres Pasos Formation, Magallanes Basin, Chile
This work summarizes Sebastian’s work on a truly unique and exceptional outcrop exposure of submarine channel system deposits. While the outcrop belt that this location is part of contains abundant quality exposures of sandstone-rich channel-fills that our group has worked on for many years, this particular location reveals details of dominantly fine-grained elements of the system (mud-filled channels and levee overbank) that are typically poorly constrained in outcrops. Sebastian collected a tremendous amount of detailed sedimentological data over a few field seasons. In this paper, which we plan to submit very soon, we present ideas about how stacking patterns in submarine channel systems change through time and also share results about deposits associated with channels in their “young” phase, which are rarely preserved.
(2) Stratigraphy and Syn-Depositional Faulting of an Overbank Succession in a Large Submarine Channel-Levee System, Upper Cretaceous Cerro Toro Formation at El Chingue Bluff, Southern Chile
This chapter presents new findings about another outcrop in the Magallanes Basin that has been visited numerous times over the years, but lacked sufficient amount and type of data to be fully understood. The ~500 meter-thick exposure of dominantly fine-grained and thin-bedded turbidites also contains numerous normal faults that had previously been interpreted to be syn-sedimentary in nature. Sebastian generated an amazing field data set that integrated sedimentological information with structural measurements (e.g., fault orientation/attitude) to finally test these ideas. These new data, combined with previously published age control from our group, suggest that most of this succession is part of a slope system associated with the overbank of the very large Cerro Toro channel-levee system. The paper that summarizes this study discusses the possible controls of this depositional-deformational interaction and will be submitted later this year, so look for it in 2023!
(3) Deciphering the Depositional Age of Coarse-Grained Deep-Marine Sedimentation in a Previously Undocumented Location in the Magallanes Foreland Basin, Southern Chile
Sebastian’s final chapter ‘zooms out’ in scale and considers regional paleogeography of generally similarly aged depositional units in the region south of Puerto Natales, Chile, which was essentially frontier territory (geologically speaking). The relationship to the better-studied units to the north had been assumed for decades based on large-scale geologic mapping, but there wasn’t any actual age control. Sebastian led multiple excursions to this very-difficult-to-access location to collect samples for detrital zircon geochronology. Due to the relatively high abundance of nearly contemporaneous zircons in Magallanes Basin strata, we’ve been able to constrain depositional ages of stratigraphic units much more accurately than previously known. Sebastian’s work shows that the conglomeratic deposits that make up the bulk of this location are actually younger than similar-looking units to the north and, therefore, likely represent a wholly different sediment-routing system.
As I mentioned in the recent post about Drew Parent finishing, it’s always so bittersweet — when graduate students succeed, that means they leave! I am so happy to have worked with Sebastian on these projects and look forward to future collaborations (and getting these papers out!). Sebastian has moved back to Chile and will be working on numerous interesting educational, public outreach, and research projects as an independent consultant. Congratulations Sebastian!!
