Faizan Sabir TahirKheli is sedimentary geologist interested in reconstructing paleoclimate evolution, recent glacial-interglacial events, physical sedimentology processes, and understanding related stratigraphic record.  

Faizan’s research will focus on recent glacial and interglacial episodes by applying physical sedimentology techniques on deepwater sediments. His project will consider the complete depositional history of sediment from source to sink and link past climate trends with current/future global warming patterns. Faizan will center his work on core samples and data from IODP Exp 400 (NW Greenland Margin).

Faizan has a BS in Paleontology and Advanced Stratigraphy and a MPhil degree specializing in Sedimentology. His background includes extensive research on carbonate and siliciclastic rocks, including microfossil studies and diagenesis analysis using thin sections. Faizan’s broader experience spans sedimentology-stratigraphy, geo-mapping, groundwater surveys, and lab work involving sediment analysis and thin sections from various sedimentary rocks. 

In addition to his academic and professional work, Faizan enjoys collecting rocks to prepare tumble stones and studying fossils and grains in rock sections under the microscope. 

Welcome to the Sedimentary Systems Research Group Faizan!!

Congratulations to (now former) SSR graduate student Michala Puckett on successfully defending her thesis in May 2024 and officially graduating from the program and obtaining her M.S. degree! Michala, originally from Mooresville, North Carolina and a graduate of Appalachian State University, joined the SSR group in August 2022 and worked on a project as part of the Chile Slope Systems research program for her master’s thesis.

Michala’s thesis, titled Variability of sedimentary texture in deep-marine channel sandstones: Insights from petrographic characterization of Cretaceous Tres Pasos Formation, Chile, leveraged spectacular outcrops of submarine channel deposits we’ve studied for many years in the Upper Cretaceous Tres Pasos Formation in the Magallanes Basin. Multiple Ph.D. and M.S. projects from over the years provided the stratigraphic and architectural context for Michala’s work, which focused on micro-scale texture (specifically grain size and sorting).

Michala analyzed 57 samples of the medium- to thick-bedded structureless sandstone facies that is dominant in the channel-fill deposits. The samples were organized into transects of several well-documented channel-fill exposures with the idea to investigate trends and patterns in grain size and sorting that aren’t quantifiable through field observation alone. The results are intriguing and we are designing a follow-up study to characterize the composition of these sandstones in more detail.

It was such a pleasure having Michala in the group and we will miss seeing her in the lab. A master’s degree goes so fast! Michala has already landed a job in the environmental consulting industry in North Carolina. Congratulations Michala!

The first bit of news in this update is to congratulate Dr. Natalia Varela on successfully completing her Ph.D.! Natalia passed her defense in December 2023 and submitted the dissertation and officially finished the degree in January 2024. Natalia’s research focused on sediment samples and data from two International Ocean Discovery Program (IODP) expeditions: Exp 374 in the Ross Sea (which I sailed on in 2018) and Exp 396 along the Norwegian margin (which Natalia got to participate on in 2021).

Stay tuned for some fantastic papers in the coming year led by Natalia and based on her dissertation research, including the Pliocene-Pleistocene history of turbidite sedimentation offshore West Antarctica. Natalia is now at University of Virginia (just ‘up the road’ from Blacksburg) to continue her work on Antarctic margin sedimentation as part of a post-doctoral fellowship in Dr. Lauren Miller‘s lab.

I’d like to also acknowledge Natalia’s contributions to the department’s education mission. Natalia was not only an excellent TA for several different courses and levels, but was instrumental in helping design and develop a brand new course, an introductory paleoclimate course for any major/year called Climate History. Natalia won a much-deserved teaching award from the department in 2023 acknowledging these achievements. It’s been such a privilege to work with Natalia these past years, we miss her already!

Last month, I traveled to southern Chile to co-lead a field workshop for the sponsors of our Chile Slope Systems project. I realized that this year is my 20th anniversary of first visiting these amazing outcrops (my first field season as a new Ph.D. student in 2004). Time flies! We had a small, but enthusiastic, group for this year’s field workshop. Along with the co-directors of CSS, Lisa Stright (Colorado State Univ) and Steve Hubbard (Univ of Calgary), and SSR alum Sebastian Kaempfe, we showed off some of the ‘classic’ Tres Pasos Formation submarine channel-fill outcrops as well as sharing some of our newest results.

Although she didn’t make the trip to Patagonia this year, we presented results from Michala Puckett‘s M.S. thesis research, which examines the grain-scale textural characteristics of these sandstones. Michala is on track to finish her master’s in the next several weeks. Below is a photo of Michala presenting her research at the department’s Geoscience Student Research Symposium (GSRS) event a couple of weeks ago.

Finally, I’m very pleased that our research on the response of deep ocean circulation in the North Atlantic to significant climate change at the Eocene-Oligocene Transition (EOT; ~34 Ma) is now out in Paleoceanography and Paleoclimatology. This study goes back several years, starting with Kristin Chilton (M.S., 2016) with the foundational work on Site U1411 and then Drew Parent (Ph.D., 2022) generated data from a second site (Site U1406) and led the integrated analysis. We applied the terrigenous grain-size proxy ‘sortable silt’ to the fine-grained contourite drift deposits on the Newfoundland ridges to investigate the physical bottom-current history during this pivotal transition in Earth’s climate. The samples for this work came from IODP Exp 342, which I sailed on back in 2012. I’ll also note that this new work with sample-based proxy data is an appropriate follow-up to the regional seismic-stratigraphic research of these drift systems led by Patrick Boyle (M.S., 2014), summarized in our 2017 paper in Marine Geology.

Congrats to Drew, Kristin, and the rest of the author team!

This post provides an update on the activities of the Sedimentary Research Group over the last year or so. Despite the challenges that the COVID-19 pandemic has caused — most notably, the inability to travel for field work, sample collection, and some lab work — the group is thriving and making advancements in our research. Also, SSR director Brian Romans is looking for a new graduate student to join the group (starting in August 2022) at either the M.S. or Ph.D. level. Please contact Brian to learn more (contact info here).   

SSR Group Member Activities:

PhD student Drew Parent presented preliminary results from his project on detrital zircon geochronology along the U.S. Atlantic passive margin at the virtual GSA 2020. (See a video recording of this talk here.) This work is part of a broader collaboration with students and faculty at UT-Austin as well as SSR alum Cody Mason, ultimately aimed at reconstructing the evolution of sediment dispersal systems during and after the rifting of Pangea. Drew worked as an intern with the Clastic & Seismic Stratigraphy group at Chevron this summer and will be starting full-time at Shell in Houston, TX in January 2022.

PhD student Sebastian Kaempfe will be presenting some of his research at the SEG-AAPG IMAGE conference in September 2021. His presentation is titled “Early-stage slope-channel fill deposits preserved at the base of an interval levee succession, Late Cretaceous Tres Pasos Formation, Chile” and will summarize some of the results from his research in southern Chile as part of the Chile Slope Systems program. This specific project is one chapter of Sebastian’s dissertation and presents new insights into deposits interpreted to have accumulated in an active sediment pathway that was subsequently abandoned, thus preserving a phase of channel development that is commonly observed in modern seafloor, but not in the stratigraphic record. 

PhD student Natalia Varela participated in two virtual conferences this past summer (2021 SEPM ISGC Virtual Student and Early Career Sessions and the U.S. Scientific Conference Antarctic Research [SCAR]) where she shared her work on the sedimentology of the turbidite record on the levee of the Hillary Canyon, a submarine channel that is a conduit for Antarctic Bottom Water (AABW) formation in the Ross Sea, Antarctica. This research is part of IODP Exp 374, which Brian Romans sailed on in early 2018, and focuses on ocean and ice-sheet interactions in the Pliocene-Pleistocene. All the SEPM talks, including Natalia’s, can be viewed on their YouTube channel. Natalia is right now in the North Atlantic Ocean participating as a shipboard scientist on IODP Exp 396 (Mid-Norwegian Continental Margin Magmatism) — the photo below was taken aboard the JOIDES Resolution drillship a few days after they left port to begin the expedition.

New Publications From the SSR Group:

PhD student Drew Parent and SSR director Brian Romans are co-authors on a new paper out in Sedimentology summarizing a collaborative study with Kyle Strom and students in the Civil & Environmental Engineering department to test the physical paleoceanographic proxy known as ‘sortable silt’. Our study generated grain-size data from deposits produced in a controlled setting (laboratory flume) and shows that mean sortable silt (10-63 µm) correlates well with flow velocity (see figure below), suggesting that under certain conditions this proxy is a reliable indicator of bottom-current speed. We have a follow-up paper, led by Drew Parent, in the works that dives into more details about how our experimental results compare to studies that measured bottom currents and grain size in natural systems. Stay tuned!

Brian Romans is a co-author on a new paper out Frontiers in Earth Science titled Times Associated with Source-to-Sink Propagation of Environmental Signals During Landscape Transience that proposes a common conceptual language and definition for aspects related to how signals (e.g., climate, tectonic, anthropogenic) are transferred and preserved in stratigraphic archives. We focus on the various temporal aspects and hope to engage with different Earth science disciplines involved in these ideas (e.g., geomorphologists, hydrologists, sedimentologists, climatologists, and more). For example, the figure below discusses how signals associated with specific grain-size (hydraulic) fractions may have different signal arrival times, which could impact how we interpret stratigraphic archives.    

Sedimentary Systems Research group alum Neal Auchter (Ph.D. 2016) has a new paper out in Geology based on one of his dissertation chapters.

In this study, we use strontium isotope stratigraphy on reworked fossil fragments from the Cretaceous Tres Pasos Formation (southern Chile) to document sediment recycling. Strontium isotope stratigraphy is an established method to determine numerical ages of primary calcium carbonate from the 87Sr/86Sr ratio. This works better in some periods of Earth history than others, and the Late Cretaceous is one of those periods. Check out this 2012 review by McArthur and co-authors to learn all about this method.

However, we apply strontium isotope stratigraphy in a different way. Instead of determining 87Sr/86Sr from shelly fossils found in situ (e.g., in growth position), we made this measurement on fossil fragments found in coarse-grained turbidite deposits. In other words, the fossils were eroded, transported, and deposited some time after they formed. The conceptual diagram below (Fig. 1 from the paper) puts into context our use of strontium isotope ages with commonly used zircon (U-Pb) dating methods. The important difference between detrital zircon and detrital strontium, however, is that the latter helps constrain recycling from within the marine basin.

Over the course of a few field seasons, Neal and others in the Chile Slope Systems team collected shell-fragment samples from across the ~100 km-long Tres Pasos outcrop belt. The figure below (Fig. 3B from the paper) summarizes the detrital strontium isotope stratigraphy data (n=94 ages). The samples are organized on the horizontal axis by sample sets (L1-L13), which represent stratigraphic units whose depositional age generally youngs southward (to the right). The gray rectangles are maximum depositional age ranges as defined by our published detrital zircon work. The strontium ages are color/symbol-coded by specimen type (inoceramid, oyster, gastropod, and bivalve).

The primary observation in the data plot above is that very few of the strontium ages are within the gray rectangles. In other words, most of the strontium ages are older than depositional age and, in some cases, >10 Myr older. We interpret these fossil fragments to have been recycled during Tres Pasos deposition. For example, downcutting by a submarine canyon could have tapped into the underlying older deposits that were then transported further into the basin via turbidity currents. Considering the tectonically active setting, even minor uplift along the basin margin, could have contributed to the exhumation of shallowly buried deposits then available to be reworked further into the basin.

Although there is uncertainty about the exact mechanism (or combination of mechanisms) that led to the recycling we emphasize that with this method we can (1) document that intrbasinal recycling is occurring and (2) constrain the residence time of shelly fossils between initial calcium carbonate precipitation and eventual deposition. The figure below (Fig. 4 from the paper) depicts the regional stratigraphy and our interpretation of how proportions of specimen type (namely, inoceramid versus oyster) represent intrabasinal source terranes. Check out the paper — it’s open access! — for all the details.

Congrats to Neal on getting this work out there! It can take a lot of effort to get a thesis/dissertation chapter refined, submitted, and eventually published after graduate school is officially done (for example, when life events and new opportunities become the priority).

It’s been an exciting several months since the last update. The Sedimentary Systems Research group and collaborators are busy working on a bunch of different projects.

First off, some papers that have been published so far in 2019:

• SSR group alum (PhD student and post-doc) Cody Mason, now an assistant professor at University of West Georgia, led a paper published in Geology about our work on the Amazon sediment routing system: Detrital zircons reveal sea-level and hydroclimate controls on Amazon river to deep-sea fan sediment transfer
• Collaborators Allie Jackson and Lisa Stright (co-PI of Chile Slope Systems project) led a paper that is in the ‘ahead of print’ section for AAPG Bulletin summarizing a study using detailed outcrop data to examine reservoir characteristics: Static connectivity of stacked deep-water channel elements constrained by high-resolution digital outcrop models
• Chile Slope Systems PhD student (at University of Calgary), Ben Daniels, led a paper in Journal of South American Earth Sciences that presents an updated chronostratigraphic framework for the strata we’ve been working on in southern Chile for many years now: Revised chronostratigraphic framework for the Cretaceous Magallanes-Austral Basin, Ultima Esperanza Province, Chile
• Brian Romans contributed to a study led by James Spray (based on his PhD work at University of Southampton) published in Paleoceanography and Paleoclimatology examining the characteristics of sand grains within dominantly muddy contourite drifts offshore Newfoundland to address long-standing questions about timing of initiation of significant land ice in the Northern Hemisphere: North Atlantic evidence for unipolar icehouse state at the Eocene-Oligocene Transition

We have a couple other papers currently in review and several others in the pipeline for 2020.

Here’s a brief update of what we’ve been up to so far in  2019 (this is just a sampling):

Sebastian Kaempfe (PhD student) had another successful field season in southern Chile in February-March, collecting loads of data for all three chapters of his PhD dissertation. He presented a poster at the AAPG Annual Meeting in San Antonio in May 2019 as well as presenting an update to the sponsors of the Chile Slope Systems program. The biggest highlight of the past several months for Sebastian is successfully passing his PhD preliminary examination, congrats SK!!

Natalia Varela (PhD student) had another busy spring semester, taking multiple classes and TAing our department’s “Resources” course for non-majors. During the semester and into this summer, she has been hard at work in our lab processing samples from IODP Exp 374 (West Antarctic Ice Sheet History, Ross Sea) and generating grain-size data. Natalia also attended the Antarctic Core Workshop in June 2019 organized by IODP and held at Texas A&M University.

Drew Parent (PhD student) is juggling multiple research projects this summer, making significant progress on finalizing the data set of terrigenous grain-size data from Newfoundland contourite drifts (IODP Exp 342), which we are using to reconstruct the history of deep-ocean circulation in the North Atlantic in response to the Eocene-Oligocene Transition. Additionally, he and Brian Romans visited the Maryland Geological Survey in May 2019 to sample cores of Early Cretaceous sandstones for detrital zircon work. Drew visited Danny Stockli’s (UT Austin) lab in August 2019 to generate U-Pb ages from detrital zircons from U.S. Atlantic continental margin sandstones.

Brian Romans (director of SSR) finished the second half of a speaking tour for the IODP Discovery Lecture Series in the early part of 2019 with visits to Scripps Institution of Oceanography, University of Cincinnati, Colorado School of Mines, University Texas Austin, University Nebraska-Lincoln, and University of Arkansas. In the spring semester, Brian led a graduate student seminar on deep-marine depositional systems where eleven students chose topics, readings, gave a presentation, and led a discussion. Thanks to the enthusiasm and efforts of the participating students we also ran a field trip to outcrops in the region to view sediment gravity flow deposits in Paleozoic strata.

It’s been quite a while since I provided an update on what the Virginia Tech Sedimentary Systems Research group is up to. Here’s a rundown of our activities over the past several months:

First, although it’s always sad to see a member of the group leave, I am also filled with joy to see them move on to the next stage. Former PhD student and post-doc of the group, Cody Mason, is now an Assistant Professor at the University of Western Georgia. Cody finished up his post-doc in summer 2018 and started at UWG that fall. We have some results from detrital zircon studies of the Amazon submarine fan we shared in this EarthArXiv pre-print, with the peer-reviewed paper (hopefully) coming very soon. I’m looking forward to collaborating with Professor Mason in the years to come!

Ph.D. student Natalia Varela has finished her first full year in the program and has hit the ground running. In summer 2018, Natalia attended the IODP Petrophysics Summer School in Leicester, UK and, later that summer, participated in the IODP Expedition 374 sampling party at the Gulf Coast Repository at Texas A&M University. Natalia’s dissertation research is focused on Miocene through Pleistocene continental slope deposits recovered during IODP Exp 374 in the Ross Sea, Antarctica (read the Exp 374 Preliminary Report). In addition to her research activities, Natalia has also been a teaching assistant for Sedimentology-Stratigraphy and Natural Resources courses.

Ph.D. student Sebastian Kaempfe is in southern Chile right now for his third field season. His dissertation research is part of the industry-funded Chile Slope Systems project, a multi-institution collaboration with colleagues and students at the University of Calgary and Colorado State University. Sebastian presented preliminary results of the first chapter of his dissertation work at the AAPG Annual Convention and Exhibition in May 2018 and also participated in the annual Chile Geological Congress in Concepcion, Chile in November 2018. Sebastian TA’d the Sedimentology-Stratigraphy course in fall 2018.

Ph.D. student Andrew Parent has been quite busy both leading and contributing to various different projects. A lot of progress was made in generating a late Eocene-mid Oligocene terrigenous grain-size record from IODP Site U1406 (Newfoundland Ridge drifts) to complement former SSR student Kristin Chilton’s record from Site U1411. Drew presented a poster with these new data at the AGU Fall Meeting in Washington, D.C. in December 2018. Drew and I have also been collaborating with researchers in the Civil & Environmental Engineering department on an American Chemical Society-funded grant on ‘sortable silt’ flume experiments. CEE master’s student Jeff Culp presented a poster of our preliminary results at AGU. Finally, Drew worked with collaborators in the Mining Engineering department to help with seismic stratigraphic characterization of the South Carolina Trough for a Dept. of Energy-funded project to characterize offshore carbon storage potential.

As for me, I’ve been traveling around the U.S. as one of the IODP distinguished lecturers for the 2018-2019 academic year. I’m honored to be among the six lecturers for this year and have been having tons of fun sharing our IODP science. My talk summarizes our work on the Newfoundland drifts (Exp 342) and previews the research to come from the Ross Sea (Exp 374). Here’s a 4-minute video that science communicator Kim Kenney produced as both a summary and advertisement of the talk: