Welcome to GeoUnion, the graduate student body of the Department of Earth, Environmental and Planetary Sciences. GeoUnion strives to supplement the overall graduate student experience at Rice and DEEPS. GeoUnion represents DEEPS in the overall Rice grad student community, acts as a liaison between students and faculty and organizes a number of intra- and inter-departmental events throughout the academic year.
Date | Event |
---|---|
August 19-23 | O-Week |
September 6-8 | Overnight Camping at San Marcos |
September 13 | Welcome Barbecue |
Cancelled because of Imelda | Pre-GSA talk |
October 12-15 | Field Trip to Big Bend |
October 25 | Halloween Kickball Tournament |
November 26 | Multicultural Thanksgiving! |
Dec 6 | Pre-AGU practice session |
TBA | Enlightenment |
Here’s a list of the resources that you would need to use frequently as graduate students at Rice. The websites of the Rice Graduate Student Association (GSA), Office of International Students and Scholars (OISS), Graduate and Postdoctoral Studies (GPS) are platforms which graduate students can use to keep track of upcoming events, funding opportunities, changes in rules and regulations, etc.
Living in a vast city like Houston and exploring a new place can also be challenging, and so we have compiled a list of recommendations for housing and fun things to do in the Space City!
Manik Talwani wins 2015 Maurice Ewing Award from the SEG
Our Manik Talwani received the Society of Exploration Geophysicist’s Maurice Ewing Medal this year. From the SEG wiki:
“The 2015 Maurice Ewing Award goes to Dr. Manik Talwani who received his PhD in 1959 from Columbia University under the tutelage of Doc Ewing, who would be justifiably proud of his student. Manik has received an amazing list of awards including the James B. Macelwane Award and the Maurice Ewing award from the American Geophysical Union, the Alfred Wegener Medal from the European Union of Geoscience, the Emile Wiechert award from the German Geophysical Society, the George P. Woollard Award from the Geological Society of America, and the Krishnan Medal from the Indian Geophysical Union, among others. In addition he has been awarded fellowship in several prestigious societies including the Russian and Norwegian Academies of Science, and an Honorary Doctorate of Philosophy from the University of Oslo. He has served in an impressive list of professional positions including Director of the Geotechnology Research Institute of the Houston Advanced Research Center, Chief Scientist at the Gulf Research & Development Company, Director of Lamont-Doherty Geological Observatory, and as Schlumberger Professor at Rice University. He has published more than 150 articles on a wide array of geophysical topics and has edited 7 geophysical books. Manik has served the SEG for many years, most recently as Chair of the SEG Advanced Modeling Corporation (SEAM).”
Combinatorial effects on clumped isotopes and their significance in biogeochemistry
A new paper from Laurence Yeung on the fundamentals of “clumped-isotope” fractionation, was recently accepted in Geochimica et Cosmochimica Acta. It shows, through simple theoretical arguments, the factors influencing the occurrence of rare-isotope pairs in molecules when they are made. One might be able to base future tracers of biogeochemistry on these principles.
One of the findings is also a convenient practical summary: When playing Craps, never bet on snake eyes if you suspect the dice are loaded―it, along with the other hard rolls (double threes, double fours, etc.) are less likely to come up when the dice are not evenly weighted.
doi: 10.1016/j.gca.2015.09.020
Abstract
The arrangement of isotopes within a collection of molecules records their physical and chemical histories. Clumped-isotope analysis interrogates these arrangements, i.e., how often rare isotopes are bound together, which in many cases can be explained by equilibrium and/or kinetic isotope fractionation. However, purely combinatorial effects, rooted in the statistics of pairing atoms in a closed system, are also relevant, and not well understood. Here, I show that combinatorial isotope effects are most important when two identical atoms are neighbors on the same molecule (e.g., O2, N2, and D-D clumping in CH4). When the two halves of an atom pair are either assembled with different isotopic preferences or drawn from different reservoirs, combinatorial effects cause depletions in clumped-isotope abundance that are most likely between zero and –1‰, although they could potentially be –10‰ or larger for D-D pairs. These depletions are of similar magnitude, but of opposite sign, to low-temperature equilibrium clumped-isotope effects for many small molecules. Enzymatic isotope-pairing reactions, which can have site-specific isotopic fractionation factors and atom reservoirs, should express this class of combinatorial isotope effect, although it is not limited to biological reactions. Chemical-kinetic isotope effects, which are related to a bond-forming transition state, arise independently and express second-order combinatorial effects related to the abundance of the rare isotope. Heteronuclear moeties (e.g., C–O and C–H), are insensitive to direct combinatorial influences, but secondary combinatorial influences are evident.
In general, both combinatorial and chemical-kinetic factors are important for calculating and interpreting clumped-isotope signatures of kinetically controlled reactions. I apply this analytical framework to isotope-pairing reactions relevant to geochemical oxygen, carbon, and nitrogen cycling that may be influenced by combinatorial clumped-isotope effects. These isotopic signatures, manifest as either directly bound isotope “clumps” or as features of a molecule’s isotopic anatomy, are linked to molecular mechanisms and may eventually provide additional information about biogeochemical cycling on environmentally relevant spatial scales.
Read more about the research in the Yeung Lab at yeunglab.org.
Mixed Carbonate–Siliciclastic Sedimentation Along the Great Barrier Reef Upper Slope: A Challenge to the Reciprocal Sedimentation Model
MIXED CARBONATE–SILICICLASTIC SEDIMENTATION ALONG THE GREAT BARRIER REEF UPPER SLOPE: A CHALLENGE TO THE RECIPROCAL SEDIMENTATION MODEL
BRANDON B. HARPER, ÁNGEL PUGA-BERNABE, ANDRÉ W. DROXLER, JODY M. WEBSTER, EBERHARD GISCHLER, MANISH TIWARI, TANIA LADO-INSUA, ALEX L. THOMAS, SALLY MORGAN, LUIGI JOVANE, AND URSULA RÖHL
Journal of Sedimentary Research, 85: 1019–1036, 2015.
ABSTRACT: Results of studies involving numerous cores and ODP holes along the Great Barrier Reef (GBR) margin and adjacent Queensland Trough and Queensland Plateau have challenged the use of a reciprocal sedimentation model to describe the sedimentary response of slope and basin settings to glacioeustatic sea-level fluctuations. Upper-slope sedimentation results from the relationships between sea-level fluctuations, antecedent topography, and regional climate that play an important role in the type and amount of sediment deposited on the upper slope during glacial, deglacial, and interglacial times. During the Last Glacial Maximum (LGM, . 20 ka ago) upper-slope sediments generally lacked siliciclastic material and are characterized by very low accumulation rates, whereas early deglacial-time (Termination I, TI) deposits are dominated by a siliciclastic and neritic carbonate pulse. Siliciclastic sedimentation was significantly reduced in the Holocene, while carbonate sedimentation remains elevated. A new borehole, IODP Expedition 325 Hole M0058A (Hole 58A), recovered 82% of a 40.4 m hole on the upper slope east of Noggin Passage on the central GBR margin near Cairns, Australia. Hole 58A provides a detailed sedimentary record during Termination II (TII), Marine Isotope Stage 6/5e (MIS-6/5e), deglacial transition, and through most of interglacial MIS-5. This hole, along with two others (ODP Leg 133 Holes 820A and 819A from the upper slope east of Grafton Passage), show carbonate–siliciclastic cyclicity as the result of glacioeustatic change with the GBR shelf. Sedimentation at Hole 58A is consistent with that of previous studies along the GBR margin (focusing on the LGM to present), and extends the upper-slope sedimentary record back to TII and interglacial MIS-5. A siliciclastic pulse similar to the one during TI occurred during the penultimate deglaciation, TII; however, the maximum neritic aragonite export to the upper slope occurred not during peak MIS-5e highstand when sea level was a few meters above modern position, but subsequently during a time (MIS-5d to 5a) when lowered sea level fluctuated between 30 and 50 m below present sea level. Siliciclastic sediments were reworked and exported to the upper slope when the lowstand fluvial plain was re-flooded, whereas neritic carbonate export to the slope reached a maximum when sea level fell and much of the mid to outer shelf re-entered the photic zone, subsequent to a drowning interval. Thus, this analysis refines the mixed-sedimentation models of upper-slope sedimentation along the central GBR margin during the penultimate deglacial transgression and subsequent interglacial early and late highstand. This study provides further evidence that mixed carbonate–siliciclastic margins do not always behave in a predictable manner and that mixed margins both modern and ancient would benefit from detailed study of sediment transport in the context of sea-level rise and fall.
IMPORTANT NOTICE
Because of COVID-19, the field trip is being postponed to later (date TBD) this year. The seminar will continue via remote meetings through the end of the Spring 2020 semester.
As earth scientists we seek to understand the natural processes that have shaped the world around us through time. The most fundamental requirement to acquiring a deeper understanding of these mechanisms is through observation. EEPS has a strong heritage in field-based research that when combined with analytical excellence, produces skilled scientists with a broad view of Earth as a system. While Rice University is well placed to take advantage of a broad array of research resources, students in Houston do not always have immediate access to nearby geological sites that represent Earth as a system.
A generous gift from Mike Johnson enables EEPS students the opportunity to observe classic and fundamental geologic concepts in the field. Students are in charge of proposing, selecting and managing a field excursion that will benefit everyone in the department. A year-long seminar-based class run by the students prepares them to visit the locality they have selected. Papers are selected, presented and discussed, followed by activities that educate the students on how to run a field-based project. During the field excursion, elected stops will be led and presented by individual students. The knowledge gained before and during the field trip will cumulate into a multi-media field guide that will be made available to the department and public following the trips conclusion.
A significant benefit of a department-wide field excursion is the interaction of students with scientists from various disciplines. Many earth scientists only carry out field work with specialists in their own field. The real discoveries in modern earth science occur when the different disciplines are part of a collective discourse. This trip will have scientists with different backgrounds observe the same outcrops; fostering fruitful discussion that results in the generation of new and unique questions. In addition, this trip may inspire fellowship among EEPS graduate students that will hopefully create life-long collaborations and a cohesive department.
General route starting in Albuquerque, New Mexico
This year, EEPS elected to utilize Mike Johnson’s gift to lead graduate students on a 7 day field expedition to observe some of the most diverse and economically important geologic terrains in the United States.
In early June of 2020, EEPS will travel through New Mexico, Colorado and Utah, which have easily accessible exposures of metamorphic, sedimentary, and igneous rocks. Starting from Albuquerque, New Mexico they will explore the Rio Grande Rift, the San Juan Volcanic field, and the well exposed Mezozoic stratigraphy on the Colorado Plateau. Observing these diverse geologic terrains will give EEPS graduate students a chance to see how their research interests dovetail with what they observe in nature and provide opportunities to create new ideas.
Pre-Trip planning seminars
Fall semester: The graduate student of the winning field trip proposal organizes a weekly reading group focusing on the regional geology of the four corners region and come up with potential stops.
Spring semester: The weekly reading group continues. Students pick the final outcrops that they would like to visit. Each student is assigned to be an expert on 1-3 stops. Before the field trip, each student will submit their description(s) of their stop for the field guide.