Author Archives: Brian Romans

Winter 2019 Update

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:

Welcome new Ph.D. student Natalia Varela

I’m very happy to welcome Natalia Varela to the VT Sedimentary Systems Research group. Natalia arrived in January 2018 as a Ph.D. student.

Natalia is from Santiago, Chile, and received a Bachelor’s in Geology at the Universidad de Concepción in 2009 and earned her professional degree in 2015. She has participated in several stratigraphy-related projects in central Chile, Patagonia, and Antarctica, studying the organic portion of Cretaceous formations and their correlation with the depositional environment. Natalia also has experience working as a geologist for energy, mining, and environmental companies.

Natalia will be working on IODP Expedition 374 (Ross Sea West Antarctic Ice Sheet History) samples and data for her dissertation research. Specifically, Natalia will use the occurrence and character of thin-bedded, overbank turbidites recovered from a core drilled on a continental rise canyon-channel system to investigate the Antarctic Bottom Water (AABW) production history in the Pliocene-Pleistocene. For another project, Natalia will use downhole logs from a continental shelf site in the Ross Sea to characterize ice-sheet-proximal lithofacies and examine ice sheet advance/retreat history over the past ~17 million years.

We are excited to have her on board. ¡Bienvenida Natalia!

New paper on catchment-fan system erosion rates during Pleistocene climate change

We have a new paper out in Earth and Planetary Science Letters led by former Sedimentary Systems Research group Ph.D. student and current post-doc Cody Mason.

Sediment supply has long been considered an important factor in observed depositional patterns and facies in sedimentary basins. Indeed, accommodation and supply are commonly invoked as the two fundamental controls on stratigraphy. However, directly measuring paleo-sediment supply from the stratigraphic record is a significant challenge. In most cases, sediment supply is estimated in a relative sense. Thus, the aim of this study was to calculate sediment supply, in an absolute sense, from outcropping Pleistocene alluvial and lacustrine deposits using cosmogenic radionuclides. We applied the catchment-integrated denudation (erosion) rate methodology that is typically used for modern river sediments to a succession of now-exhumed catchment-outlet deposits in Panamint Valley, California. This approach allowed us to generate a time series of paleo-erosion rates (which we use as a proxy for sediment supply).

The figure below (Fig. 6 from the paper) is a summary of our results. In order to calculate paleo-denudation rate we needed some constraint on depositional age, which we got using 10Be/26Al burial dating techniques. The ~180 m thick succession we studied ranges from ~1.2 Ma to ~0.3 Ma old (part D of the figure below). 

The resultant denudation rates (part E of figure above) show that the sediment supply out of the catchment varied from as low as ~24 mm/kyr to as high as ~54 mm/kyr with a long-term mean rate of ~36 mm/kyr. In the paper, we discuss the potential controls of glacial-interglacial climatic variability and Mid-Pleistocene Transition on source-to-sink dynamics. Additionally, we present an end-member mixing model to explore how sediment storage and/or landslide processes in the upper catchment may have influenced our paleoerosion rate calculations.

If you cannot access the EPSL version, you can get a freely available version on EarthArXiv (or feel free to email us and we can send you a copy).

Additional thanks to Ron Schott for joining us out in the field area during one our trips to take some beautiful GigaPan images of the outcrop (see the images called ‘Ballarat Delta’).

A couple short videos from Exp 374

Here are a couple of short videos I took during IODP Expedition 374 that I wasn’t able to upload last month because of poor internet connectivity.

This first one is from when we were escorted through the sea ice by the R/V Palmer:

This one is of me heading out to the deck with my beginning-of-shift (midnight, in this case) coffee; something I would try to do every day unless the weather was really bad:

Core on Deck

A core being carried onto the catwalk by IODP technicians during Expedition 374

This is the phrase that participating scientists on IODP expeditions love to hear. When a new core is brought up to the rig floor of the JOIDES Resolution (the JR) from beneath the seafloor, the driller’s announcement of “core on deck” comes through the speakers in all the labs. At this point, multiple people leap into action and prepare for the new core. The IODP technicians get ready to accept the (hopefully full) 9.5 meter (~30 ft) long core. The drilling crew lays the core down horizontally on the drill floor, with the base of the core facing the ‘catwalk’, and a technician will get small piece from the base of the core (called the core catcher) and hand it off to one of the paleontologists.

The paleontology lab will immediately start to process the sediment to isolate and identify microscopic fossils and fossil fragments that will provide information about the age of the deposits (an application of paleontology called biostratigraphy). The rest of the core is put on a rack on the catwalk at which point the IODP curator will measure, assign identification to the core, and prepare it to be cut into 1.5 m long sections. Once the sections are created they are carried into the lab and put on a rack to equilibrate to surface temperatures (~4 hours).

The whole-round core sections will then go through a series of measurements (natural gamma radiation, magnetic susceptibility, P-wave velocity, bulk density) that aid the science party in characterizing the sediments even before they are split. The IODP techs will then split the cores, creating a ‘working’ half and an ‘archive’ half. The working half is sampled for additional measurements (density, moisture content, porosity, paleomagnetics, geochemistry, paleontology) and the archive half is thoroughly described. By the time any single core makes it through this process, the biostratigraphy lab team will have a preliminary age for that core. (In some cases, they have an age within 10 minutes of getting the core catcher!) The paleomagnetism lab team will also generate an age model based on magnetostratigraphy, which can be compared with the paleontology team. After ~24 hours of that core coming on deck, the geochemistry lab team will have initial results about general composition (e.g., % of calcium carbonate). This shipboard characterization provides the foundation for research that is done several years or even decades after the expedition.

Photo from a drone during Exp 374 taken by IODP photographer and imaging specialist Bill Crawford

The JOIDES Resolution (JR) is a unique science vessel. There are many ships that can perform any number of tasks for oceanographic and marine science. But, the JR is different because it’s a time machine. Only through deep coring into the seabed can we extract the record of past processes and environments.  The sound of “core on deck” is music to the ears of geoscientists on board excited to make new discoveries about how the Earth works.

More photos of Exp 374 here: https://iodp.tamu.edu/scienceops/gallery/exp374/

The Transit from New Zealand (43°S) to the Ross Sea (76°S)

We left port at Lyttelton, New Zealand just over a week ago and have been cruising almost due south ever since. In ~36 hours we will rendezvous with the R/V Palmer, a polar-class icebreaker, who will escort us through some sea ice. The sites we plan to drill are in ice-free areas (called polynyas) but we need the icebreaker escort to get us to those areas. At some point before our rendezvous with the Palmer, we will cross both the Antarctic Circle (66°33′,47”S) and the International Date Line. (However, we will be staying on NZ time to avoid mass confusion!)

The transit included a few days of some high winds and up to 6 m high waves. The Southern Ocean (the ocean surrounding the Antarctic continent) is notorious for this kind of weather and, although it wasn’t as bad as it can get, it was still a rough ride. Thankfully, I do not get seasick, but several others in the science party weren’t feeling particularly well. Here’s a video from the bridge of the JR the other day showing the ~6 m waves (with bonus albatross).

The seas have calmed down a bit and the science party has begun moving on to their shifts (either noon-to-midnight or midnight-to-noon). I’m writing this post as I try to remain awake after staying up all night in an attempt to transition to the midnight-to-noon shift. Up until today, the science party has been all in a normal day shift and working in their lab teams to learn procedures. It’s a challenge to effectively ‘practice’ what we’ll be doing without core actually coming up, but it’s still a good idea to get some familiarization with the equipment and overall workflow. I’ll write more about what analyses are done and what data are collected in a future post.

We’ve also spent time during the long transit to learn more details about the coring operations (via tours and presentations; photos below) and to write/edit the methods sections for the expedition report that we, as a collective, will be creating as we go.

When we get to our first drilling location we will have traveled 33 degrees of latitude (from 43°S to 76°S), or approximately 3,660 km (2,270 miles) during this transit. The Earth’s oceans are vast, the JR is designed for long transits to get to where we need to go.

Getting ready to set sail

I’ve been in Lyttelton, New Zealand (port town close to Christchurch) the past few days during our port call. The science party typically boards and moves onto the JOIDES Resolution (the JR) during port call to begin getting familiar with the ship, the labs, the people, and more before we actually depart. Meanwhile, the crew for the ship is offloading cores (and other freight) from previous expedition and preparing for the new expedition. All this typically takes a few days, which allows the scientists to get off the ship in the afternoons/evenings.

We set sail in just a few hours and it will be an ~8-day transit to our first coring site in the Ross Sea. During this transit we will continue to work in our lab groups (more about all that in a subsequent post) and get ourselves ready for the first core on deck.

Being able to get off the ship also allows getting a view looking back at the JR from off the ship, which is something we won’t be able to do for two months. What a beauty!

Finally, just wanted to point to this very nice story by the College of Science communications team that was posted on Virginia Tech News the other day. This is a wonderful overview of the objectives of the expedition.

Brian Romans to sail on IODP Exp 374 to study West Antarctic Ice Sheet history

I’m very excited to announce that I will be participating as a shipboard scientist on International Ocean Discovery Program (IODP) Expedition 374. This expedition leaves Christchurch, New Zealand on January 4th and will spend several weeks in the Ross Sea, offshore western Antarctica.

Here is a detailed description of the scientific objectives of this expedition (copied from the expedition webpage):

The Ross Sea West Antarctic Ice Sheet (WAIS) History Expedition will investigate the relationship between climatic/oceanic change and WAIS evolution through the Neogene and Quaternary. Numerical models indicate that this region is highly sensitive to changes in ocean heat flux and sea level, making it a key target to understand past ice sheet variability under a range of climatic forcings. The proposed drilling is designed to optimize data-model integration for improved understanding of Antarctic Ice Sheet mass balance during climates warmer than present. Core and log data from a transect of six sites from the outer continental shelf to rise in the eastern Ross Sea will be used to: (1) evaluate WAIS contribution to far-field ice volume and sea level estimates; (2) reconstruct ice proximal atmospheric and oceanic temperatures to identify periods of past polar amplification and assess forcings/feedbacks; (3) assess the role of oceanic forcing (e.g., sea level, temperature) on WAIS instability; (4) document WAIS sensitivity to Earth’s orbital configuration under varying climate boundary conditions; and (5) reconstruct eastern Ross Sea bathymetry to examine relationships among seafloor geometry, ice sheet instability, and global climate.

I am thrilled to be participating in this exciting expedition and looking forward to expanding the scope of the Sedimentary Systems Research group into ice sheet and glacially influenced marine sedimentary processes as well as investigating paleoceanographic records of the Miocene and Pliocene.

I will be posting to this site throughout the expedition, so stay tuned for updates from the JOIDES Resolution.

New paper on timing of deep-marine slope system evolution using zircon geochronology

We are pleased to share our newest publication coming out of the Chile Slope Systems project. This paper is led by Univ. of Calgary Ph.D. student Ben Daniels and is now online in the journal GSA Bulletin.

This study reports >6,600 new U-Pb zircon ages from the Upper Cretaceous Tres Pasos Formation in southern Chile. We’ve been investigating the sedimentology and stratigraphic architecture of these exceptional outcrops of slope strata for many years, but haven’t had a robust understanding of the timing until now.

Ben (with the help of others in the group) collected numerous sandstone samples for detrital zircons as well as two volcanic ash deposits. Together, the new geochronologic data constrain the age of distinct “phases” within the Tres Pasos Formation across a ~100 km long by ~2 km thick outcrop belt. With this framework, we discuss rates of progradation/aggradation, comparison to other well-studied slope/margin systems, and potential external controls on the basin-scale architecture. Additionally, we also include a discussion on the use of detrital zircon to calculate maximum depositional ages (MDAs) that will be of interest to anyone using detrital zircon geochronology for sedimentary system analysis.

The figure below (Fig. 2 from the paper) is a regional stratigraphic cross section showing the large-scale architecture, paleocurrent data, and these new U-Pb ages all in one chronostratigraphic framework.  

Huge congrats to Ben on spearheading this effort!

Welcome new Ph.D. student Drew Parent

I’m very happy to welcome Drew Parent to the VT Sedimentary Systems Research group. Drew is starting his Ph.D. in the department and his dissertation research will investigate the history and patterns of deep-sea sedimentation in the western North Atlantic Ocean in response to Cenozoic climate change. Drew will employ multiple methods, including: quantitative grain-size analysis of late Eocene through Oligocene cores from the Newfoundland Ridges obtained from IODP Exp 342, experimental (flume) investigation of fine-grained sediment transport (a collaboration with Dr. Kyle Strom and students from Virginia Tech Civil & Environmental Engineering), and regional seismic stratigraphic mapping of the U.S. Atlantic continental margin.

Drew is from Springfield, Massachusetts and received a Bachelor’s of Science in Geological Sciences from Salem State University in 2015. His undergrad thesis combined seismic sonar, stable isotopes, and radiocarbon dating to reconstruct the late Quaternary paleoenvironment of a glacial lake in northwest Iceland; this geophysical-geological approach fueled his interest in these types of investigations (similar to the research that will make up his Ph.D. here at Virginia Tech). Drew then went on to graduate school at Wright State University in Dayton, OH, where he finished a Master’s of Science in Earth and Environmental Sciences this past April (2017). Drew’s M.S. thesis is titled “Pre-Mt. Simon seismic sequences below west-central Indiana: local interpretation and regional significance”. This research employed regional 2-D seismic reflection and potential field data to assess the composition and deformational history of the poorly understood pre-Mt. Simon below the eastern U.S. mid-continent.

Welcome to the department and Sedimentary Systems Research group Drew! Check out Drew’s website here.