I was recently interviewed by a podcast called People Behind the Science, whose goal is to tell the stories of scientists and researchers from a personal point of view. That is, what path did I take to find myself doing this, what failures and successes have I experienced, and how do I keep motivated? PBtS has interviewed more than 150 scientists, including several National Academy of Science scientists.
Here’s the link to my interview: http://www.peoplebehindthescience.com/dr-brian-romans/
[Note: The below is cross-posted on my long-time, but not very active, blog Clastic Detritus.]
I recently submitted a review paper along with four co-authors on the topic of signal propagation in sedimentary systems across timescales. The idea that landscapes contain within them information about controls such as tectonics and climate has been a part of our science for a very long time. But, recent advances in the measurement/calculation of rates of processes (for example, with cosmogenic radionuclides) as well as theory and modeling related to how such ‘signals’ generate sediment and propagate across the Earth’s surface to be, potentially, encoded into stratigraphy motivated us to write a review. I’ll post more about the paper once it’s gone through the review-and-revise process, but wanted to write a brief post here on the topic.
Let’s start simple. Consider a sedimentary source-to-sink system with erosional uplands (sediment production) connected to depositional lowlands and/or marine basin (sediment accumulation). A tectonic or climatic change can change the rate of sediment production in the uplands that is potentially recorded down-system as a change in deposition. The morphology and length-scales of the system play a huge role in the behavior, which, in turn affects how (or if) that up-system signal is ‘preserved.’
As analogy, consider human-made debris basins. These structures, common in steep and tectonically active mountains such as the west coast of North America, are designed to mitigate debris-flow hazards on communities built on slopes that are prone to mass failure, especially during precipitation events. Debris basins are positioned on failure-prone slopes above concentrated population and/or infrastructure and designed to capture newly liberated sediment as it flows down slope, preventing that sediment from being transferred further down slope where potential damage and/or injury could occur.
Charles Creek Debris Basin, British Columbia, Canada; photo courtesy of B.C. Ministry of Transportation and Infrastructure’s Flickr page
Essentially, these basins are localized sinks that store sediment, thus preventing the signal (in this case, a rain storm) from propagating down system as a mass-wasting event. However, if the magnitude of the event exceeds the storage capacity of the sink, part of the signal will propagate down system anyway. For example, if the volume of liberated material exceeds the volume the debris basin can hold, the excess mass would bypass the basin after it fills to capacity. For debris basins to be effective they must be emptied following an event such that the storage capacity is returned to its maximum. So, in addition, time and the accumulation of multiple events plays a critical role in system behavior. For example, the sediment volume released from a single rain storm may only be enough to fill a debris basin to 10% its capacity. But, material from >10 storms of similar magnitude, if not removed, would effectively erase the signal-stopping action of the basin, which would allow future events (signals) to propagate down system.
What is exciting (and quite daunting) is applying these concepts to much larger length-scales and much longer timescales. Over longer and longer time periods the only evidence remaining of these mass-transfer dynamics is the stratigraphic record.
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See this post from FOP about debris basins. And, if you haven’t already, read John McPhee’s “The Control of Nature,” which has a section about debris flows in the San Gabriel Mtns of southern California.
The VT Sedimentary Systems Research group has a combination of continuing ‘veterans’ and some new faces to start off the 2014-2015 academic year.
Ph.D. candidates Neal Auchter and Cody Mason are starting their 3rd year and are plugging away at their respective research projects. Neal will be working on sample preparation for strontium isotope analysis this semester. Cody is anxiously awaiting cosmogenic radionuclide results from PRIME Lab, where he spent several weeks this summer preparing his samples for analysis. We expect those data to come in any time! In addition, both Neal and Cody will be taking their Ph.D. preliminary examinations (aka ‘prelims’) later this semester.
New master’s candidate, Sarah Jancuska, joined the group this semester and will be part of the Chile Slope Systems consortium examining Cretaceous deep-marine strata in southern Chile. Sarah is diving right into graduate school by helping me teach our undergraduate Sedimentology-Stratigraphy course as a teaching assistant in addition to taking courses and starting research.
Undergraduate researcher Rachel Corrigan started some work last spring semester and will be continuing this semester, which is her last in the department. Rachel is investigating the response of a long-lived abyssal current in the deep North Atlantic Ocean to climate change at the Oligocene-Miocene boundary. She’ll be documenting changes in terrigenous grain size, including amounts of outsized material that is likely ice-rated debris.
New undergraduate researcher Eric Lahart, also in his last semester before graduating, will be doing similar work as Rachel, but over the Eocene-Oligocene boundary.
Finally, sophomore Rob Ulrich will be investigating grain-size and textural differences in thin sections of Cretaceous submarine channel sandstones. Rob will be developing and testing image-analysis methods to detect and quantify differences between sandstone deposits as a function of stratigraphic architecture.
I am teaching Sedimentology-Stratigraphy, as I do every fall, and co-teaching a graduate Basin Analysis course with colleague Dr. Ken Eriksson. In the meantime, I’m also working with co-authors on a review paper for the journal Earth-Science Reviews that discusses the propagation of tectonic and climatic signals through sedimentary systems at different timescales. We are within a few weeks of submitting and excited about the contribution.
A quick summer update from the Sedimentary Systems Research group.
We say farewell to Patrick Boyle who finished his master’s degree in May and is soon starting a career as an applied geoscientist in Houston, Texas. Pat and I are still working together this summer, along with some collaborators, to prepare a manuscript based on his thesis for submission to a journal by the end of the summer. At the same time, we welcome new master’s student, Sarah Jancuska, who will join the department next month. Sarah will be doing her research as part of the Chile Slope Systems project. So, one student out, but another student in — we remain at steady state!
Ph.D candidate Neal Auchter is away this summer doing an internship in Houston, Texas. Ph.D candidate Cody Mason spent a few intense weeks at the PRIME Lab at Purdue University last month preparing his samples for cosmogenic radionuclide (10Be and 26Al) analysis. If all goes according to plan, we should have some initial results this fall.
I’ve been spending my time working on multiple manuscripts, including a review paper to be submitted to Earth-Science Reviews next month on the topic of signal propagation in sedimentary systems across a wide range of timescales. I’m also working on some new/updated exercises for my Sed-Strat course as well as some content for a Basin Analysis course I’ll be co-teaching this fall.
I’m co-chairing a session (along with David Van Rooij from Ghent University) at the 2014 AGU Fall Meeting titled The Paleoceanographic Value of Contourite Archives. If you work on the sedimentary dynamics of contourites and/or use them to reconstruct paleoceanographic conditions, please consider submitting to the session. Abstract deadline is August 6th.
Congratulations to Sedimentary Systems Research group member Patrick Boyle on the successful completion of his master’s degree. Pat is the first student to graduate from this new research program and will be moving to Houston, Texas this summer to start a full-time job with ConocoPhillips as a geoscientist.
Pat’s thesis was focused on the investigation of the Cenozoic history of the Deep Western Boundary Current in the North Atlantic Ocean. Pat used seismic-reflection data constrained by Integrated Ocean Drilling Program (IODP) Expedition 342 cores to map the spatial and temporal distribution of deep-sea ‘contourite’ deposits and their relationship to global climatic changes. We are now finishing up a manuscript to be submitted to a journal, which will happen in the next month or so. Stay tuned for the paper!
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Also, the broader sedimentary geology group here at Virginia Tech just got back from a six-day, grad-student-run field trip examining various Paleozoic sedimentary successions in the central Appalachians. This trip was the culmination of a semester-long seminar where each student chose a topic of interest and researched potential outcrops to visit. The students then worked together to produce a field guide and planned the trip. We saw a lot of great geology and had a great time.
My collaborators and I have a new paper out in the journal GSA Bulletin about sediment transfer across deep-marine slopes as recorded in the stratigraphy of submarine channel deposits. (It’s worth mentioning that this paper is also open access!)
Deep-sea channels, as we can map them on the modern Earth surface, extend for 1000s of km into ocean basins and rival the planet’s biggest rivers as conveyors of sediment and other material. Much progress has been made in recent years in tools and technology for mapping and studying the ocean floor. Additionally, numerical modeling of the physics of sediment transport in the submarine realm is advancing our understanding of turbidity currents. However, ancient sedimentary deposits that are now exposed in outcrop provide the opportunity to examine the relationships of individual turbidity current event beds to the larger-scale stratigraphy that they construct. Examining the stratigraphic architecture allows for reconstruction of longer-term evolution of the depositional system.
With examples from exceptionally exposed strata from the Magallanes Basin in southern Chile, we emphasize the importance of the fine-grained and thin-bedded deposits that are preserved at the margins of sedimentary bodies we interpret as channels. Although the thick-bedded and coarse-grained deposits make up most of the volume of the composite features, it’s the margin deposits that contain the history of sediment transfer through the channel.
The annual American Association of Petroleum Geologists (AAPG) conference and exhibition is next week (April 6-9) in Houston, Texas, and the Virginia Tech Sedimentary Systems Research group will be there in full force.
M.S. candidate Patrick Boyle is giving a talk on his thesis research on Tuesday afternoon at 2:20pm in the ‘Turbidites and Contourites’ session. Pat is nearly ready to defend his thesis (less than a month from now!), and this talk will be his chance to show off the work he’s done to the AAPG community.
Ph.D. candidate Cody Mason is also presenting a poster and, like Neal, has some brand new data to share from recent field work in California. This poster is a chance for Cody to present preliminary ideas about the depositional evolution of the stratigraphic succession he’s been investigating.
Ph.D. candidate Neal Auchter is presenting a poster on his research on the Upper Cretaceous slope deposits of the Tres Pasos Formation in southern Chile. Neal recently returned from six weeks of field work down there and has much to share.
Finally, I will be giving a brief, and hopefully provocative, talk at the SEPM evening research session on Monday evening. If you’ve never attended the SEPM evening sessions, they tend to be more lively and informal than the ‘normal’ technical sessions during the day. In the past these have been quite fun. This year the organizers invited me, Mike Blum (Univ of Kansas), Kyle Straub (Tulane), and Ashley Harris (Chevron) to discuss allogenic and autogenic controls on deep-water stratigraphy.
Hope to see you there!
Much of the research the VT Sedimentary Systems Research group is currently conducting requires going to where the rocks/sediments are. What this mean is: travel, travel, and more travel.
Ph.D. student Neal Auchter and I spent several weeks in southern Chile doing field work on the Cretaceous Tres Pasos Formation. The photo below is from Neal’s primary field locale and highlights the stunning exposures of these submarine slope deposits. We spend so much time down there because (1) it’s very far away, so we only go once a year and (2) we need to build in days for the inevitable poor weather and the occasional logistical hurdle (e.g., vehicle trouble).
Neal had a very productive field season and is coming home with tons of data, samples, and lots of ideas about these strata.
The other field-based project going on currently is related to a component of Cody Mason’s Ph.D. research. This work is out in desert of southeastern California and is focused on mid-Pleistocene alluvial and lacustrine deposits now cropping out on at the base of the west flank of the Panamint Range. The primary goal of this trip was to collect samples for cosmogenic radionuclide analysis, which involved power tools and a lot of sieving of sand in the field.
I flew from South America to California to join Cody and his field assistant for the final couple days in the field. All went well and Cody will be moving on to the next phase of this project this spring and summer.
A quick update on happenings with the VT Sedimentary Systems Research group for winter 2014.
Ph.D. candidate Neal Auchter has been working hard the past couple weeks to prepare for the upcoming field season in Chilean Patagonia, which will be his second field season down there. Lots and lots of logistical tasks to do to prep for these international field expeditions. Neal will be down there for ~6 weeks this year.
Ph.D. candidate Cody Mason is also in field-prep mode, although he doesn’t head out to Panamint Valley, California until mid-March. He’s using this time to work up sedimentological data from the past two field seasons. The main goal of the upcoming field work is a sampling campaign, which is informed by the sed-strat information. Cody is also continuing to work up bedrock thermochronologic data for a tectonics project he’s working on with VT professor Jim Spotila.
M.S. candidate Patrick Boyle is in the final stretch of his master’s degree. After a very successful poster presentation at the AGU Fall Meeting in December, Pat now has all his data in good order and is busy writing up the results. He’s planning on defending in April. Pat will be the first graduate of this relatively new research group!
Undergraduate researcher Sarah Ault has moved on from Virginia Tech but is still working up some of the data she generated in my lab last summer and through the fall. Current undergrad researcher Chris Matthews is now helping with the final steps in the analysis of this data set, which the three of us will write up in a paper. Rachel Corrigan is a new undergrad researcher starting this semester and will be looking at the grain-size record of deep-sea sediments across the Oligocene-Miocene boundary.
Developing and refining the workflow for the particle size analysis research has taken a bit longer than anticipated, but I think we are getting really close to being able to generate a bunch of great data over the next couple of months. I’m really excited to see it all come together after all this hard work by me and these talented undergraduates.
Earlier this month I participated as a panelist on the International Ocean Discovery Program (the new IODP program) Science Evaluation Panel. This was my first experience reading/reviewing new ocean drilling proposals. I learned a ton, it was a really good experience. I will soon be heading down to Patagonia for nearly a month of field work with Neal (and some of my own) and to interact with the sponsor’s of that research as well. From Chile I will be flying straight to California to meet up with Cody in the desert for a couple of days of field work before heading home. The rest of the spring will be busy with co-teaching a grad seminar that will culminate in a six-day field trip, continuing the lab work, and guiding Pat through the end of his master’s.
A few of us from Virginia Tech Sedimentary Systems Research group will be attending and presenting at the 2013 American Geophysical Union meeting in San Francisco in a few weeks. Here’s a run-down of our activities:
Monday (morning):
Thursday (afternoon):
Friday (morning):
Friday (afternoon):
Looking forward to interacting with our friends and colleagues during the meeting. See you in San Francisco!