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Identifying spatial heterogeneity in the elemental concentration of Early Jurassic dinosaur bones

Sample localities, Early Jurassic Kayenta Formation near Gold Spring, AZ.

Adam Marsh – Ph.D. candidate

Supervisor: Tim Rowe

Fossil bone records a wealth of data used to explore the evolutionary history of vertebrate life, the growth and development of individuals during their lifetime, and the taphonomic processes that occur before organismal remains become a part of the fossil record. As geochemical technology advances, fossil bone is becoming increasingly useful in investigating how organic and inorganic chemistry affect the interaction between the rock and fossil records. Direct in-situ techniques like LA-ICP-MS allow researchers to ask questions surrounding groundwater interactions, provenance, trace element uptake, and even radiometric dates of fossil bones. These Early Jurassic dinosaur bones, belonging to the long-necked Sarahsaurus aurifontanalis and meat-eating Dilophosaurus wetherilli, are built from hydroxylapatite that comprises the mineral phase of bone tissue, providing structure to the collagen, osteocytes, blood vessels, and nerves in the bone that has long since decomposed. Five line scans were performed on each of the two thin sections of dinosaur bones while analyzing for 29Si , 31P, 55Mn, 57Fe, 86Sr, 89Y, 137Ba, 208Pb, 232Th, and 238U.

Inverse distribution of Mn (blue) and Fe (red) along a laser line traverse.  Altered (oxidized) bone areas are Fe-rich.

Inverse distribution of Mn (blue) and Fe (red) along a laser line traverse. Altered (oxidized) bone areas are Fe-rich.

Elemental concentrations generally decrease moving towards the centers of each bone. The decrease in the concentration of P towards the middle of the bone may suggest differing degrees of recrystallization in the fossil bone. Higher concentrations around the outside of the bone indicate more recrystallization and hence, a higher degree of fossilization. Phosphorus is the most abundant isotope in the bone (between 150,000 and 180,000 ppm), which is to be expected, as it is a major component of bioapatite. Strontium easily substitutes for Ca in bioapatite, and the relative ratios of P and Sr behave similarly through each line. The permineralized pore spaces are filled with calcite and are depleted in Mn, Fe, Y, Ba, and U.  The relative concentrations of Mn and Fe share an inverse relationship throughout the analyses. Reflected light microscopic images confirm that highly oxidized regions of the bones are bright red where oxidized iron is found in high concentrations. Barium is enriched in the meduallary cavity of the bones where secondary barite has crystallized. Thorium is the least concentrated analyte measured in the bones and is found almost exclusively in the outer centimeter and in larger vacuities. Uranium concentrations are fairly uniform across the bone thin sections but are quite enriched at about 1,000 ppm. The concentration of Pb is much more variable, which would cause direct U-Pb dating of the bioapatite in fossil bone to result in inaccurate dates. These line scans highlight the open-system behavior of bone and provide insight into the preservational history of these organismal remains since their burial in the Early Jurassic.

REE Analysis of Anhydrite Veins in Porphyry Copper Deposits

Microsampling anhydrite veins from an exploration core sample.  Through the use of a low uptake rate nebulizer, we are able to obtain complete elemental surveys (including the REEs) by solution mode ICP-MS from small (milligram) samples.

Microsampling anhydrite veins from an exploration core sample. Through the use of a low uptake rate nebulizer, we are able to obtain complete elemental surveys (including the REEs) by solution mode ICP-MS from small (milligram) samples.

Mark Cloos – Advisor

Aaron Hantsche – Undergraduate, Jackson School of Geosciences

Porphyry copper deposits are created by hydrothermal mineralization as fluids from the intrusive body precipitate metal-rich minerals. These sulfur rich systems have anhydrite in the veined mineral assemblage, as well as quartz, pyrite, and chalcopyrite. Using dissolved anhydrite from veins from the Ertsberg Mining District, Papua, Indonesia, we have conducted a solution ICP-MS study to obtain rare earth element (REE) concentrations. The concentrations, normalized to chondrite, have been compared with REE patterns from the intrusive bodies in the district.

My study is focused on the REE evolution of the fluid and how that can be used to determine relative distance between a vein and a source body. Anhydrite patterns with higher La/Yb appear to be further removed from the source.  Anhydrite REE patterns also show distinct positive and negative europium anomalies. This occurs because at high temperatures in aqueous solutions, europium occurs in a divalent state; at low temperatures, europium is more stable in a trivalent state. Anhydrite takes available divalent europium into its structure creating positive anomaly. At lower temperatures, further from the source, europium concentrations have been depleted resulting in a negative anomaly.

This means that REE patterns in anhydrite can be used as exploration tools for tracking intrusions in porphyry mining districts. Anhydrite sampling could provide an easy method to indicate preferential direction for exploratory drilling for ore prospects.

Fish Otoliths as Natural Geochemical Records

Sectioned polished otolith with faint horizontal line showing laser transect from core to edge.

Sectioned polished otolith with faint horizontal line showing laser transect from core to edge.

Walther Fish Ecology Lab

John Mohan, UT Marine Science Institute

Otoliths (oto=‘ear’; lith=‘stone) are biogenic carbonates that functioning as hearing organs in teleost fish and accrete permanent growth bands on daily to annual timescales.  The elemental composition of fish otoliths are derived from the ambient environment and influenced by physiology, providing detailed chemical chronologies of specific life stages and the types of environments fish encounter.  The trace elements Sr and Ba are thought to be incorporated into otoliths by substituting for Ca during precipitation of the CaCO3 crystal lattice.  Dissolved Sr:Ca and Ba:Ca ratios vary with salinity and differ between freshwater, estuarine, and marine environments.  The Walther Lab measures dissolved elemental ratios in water samples using solution-based ICP MS to characterize spatial and temporal variation in the environment.  Laser ablation ICP MS is then used measure elemental ratios in carbonate otoliths to obtain chemical chronologies that span the entire life of individual fish.  Understanding relationships between otoliths and water chemistries, allows us to test hypothesis related to fish migration at the individual and population level.  This research combines the natural time-keeping properties of fish otoliths and the analytical capabilities of ICP MS to address research questions in the field of fisheries ecology.

 

a.)  Atlantic croaker Micropogonias undulatus, b.) croaker otolith with dashed redline showing transverse sectioning plane, c.)  sectioned polished otolith with dashed yellow line showing laser transect from core to edge, d. lifetime elemental profile of Sr:Ca (blue) and Ba:Ca (red) with life stage- specific habitats indicated above, e.) dissolved Sr:Ca and f.) Ba:Ca ratios versus salinity for estuarine (squares) and marine (diamonds) water samples.

a.) Atlantic croaker Micropogonias undulatus, b.) croaker otolith with dashed redline showing transverse sectioning plane, c.) sectioned polished otolith with dashed yellow line showing laser transect from core to edge, d. lifetime elemental profile of Sr:Ca (blue) and Ba:Ca (red) with life stage- specific habitats indicated above, e.) dissolved Sr:Ca and f.) Ba:Ca ratios versus salinity for estuarine (squares) and marine (diamonds) water samples.

Assessing Migratory Habits of Southern Flounder Using Otolith Chemistry

LA-ICP-MS analysis of fish otoliths ("earstones") such as the one pictured at left (in cross section) is used to extract information about the age and growth history of fish, much as scientists use tree rings to learn about trees.

LA-ICP-MS analysis of fish otoliths ("earstones") such as the one pictured at left (in cross section) is used to extract information about the age and growth history of fish, much as scientists use tree rings to learn about trees.

Benjamin Walther & Megan Nims, UT Marine Science Institute

Project summary:

Because some trace elements vary predictably across salinity gradients, and these elements can be reliably incorporated into biogenic carbonates such as fish ear stones (otoliths), we can reconstruct fish movements in estuaries using laser ablation ICP-MS.  This project examined movements of southern flounder, an ecologically and economically important species in the Gulf of Mexico.  We sampled estuarine and fresh waters to quantify spatiotemporal variations in trace element composition for numerous tributaries in the South Texas Coastal Bend using solution-based ICP-MS, and then used laser ablation to characterize elemental variability across otoliths for approx. 260 southern flounder.  Contrary to prior expectations, a large proportion of flounder do not move into low salinity waters during their early life histories.  Laser ablation thus allows us to refine our understanding of life history strategies for important migratory species.

Link to CNS article:

http://web5.cns.utexas.edu/news/2012/10/secret-lives-fish-otolith-chemisty/

High Field Strength Element Partitioning in Peridotites and its Implications for the Interpretation of Hf Isotopic Compositions

Four-phase spinel lherzolite from the Rio Grande Rift, New Mexico olivine (transparent), clinopyroxne (green), orthopyroxene (tan), spinel (brown/opaque).

Four-phase spinel lherzolite from the Rio Grande Rift, New Mexico olivine (transparent), clinopyroxne (green), orthopyroxene (tan), spinel (brown/opaque).

Benjamin Byerly and John Lassiter, UT Austin

Clinopyroxene is generally regarded as the primary host of incompatible trace elements in spinel peridotites. This is reflected in the general agreement between cpx and whole-rock trace element patterns in peridotite xenoliths. Clinopyroxenes in peridotite xenoliths from Cerro Chato, NM, USA are LREE-enriched and have large negative HFSE anomalies with respect to the rare earth elements (Ti/Ti*, Hf/Hf*, and Zr/Zr* <1) (Byerly and Lassiter in prep.). Whole-rock trace element patterns generally reflect these trends. However, HFSE anomalies are not always present in whole-rock trace element patterns in the Cerro Chato xenoliths. Disparities in HFSE anomalies between cpx and whole rock may reflect partitioning of HFSE into other phases within the peridotite. Alternatively cpx may not be in equilibrium with the host peridotite because it may have been precipitated from a melt with negative HFSE anomalies relative to REE (e.g. carbonatite or subduction-related magma) percolating through the lithosphere. Disparities between the Lu/Hf ratios of bulk-xenoliths and cpx can have major implications for the use of cpx alone to interpret the Hf isotopic evolution of mantle xenoliths.

LA-ICP-MS is being used to determine the trace element concentrations of cpx and opx. With this data we seek to understand the partitioning between these two minerals and determine whether equilibrium has been achieved between the two phases. The size of the cpx and opx allows us to perform analyses with 150µm spot sizes to acquire high-quality data despite the low trace element concentrations in opx.

Monitoring Gold Nanoparticle Labeled Mesenchymal Stem Cells For Ischemic Repair

Figure 1. Dark field image of mesenchymal stem cells (MSCs) labeled with gold nanoparticles. Scale bar = 100 µm.

Figure 1. Dark field image of mesenchymal stem cells (MSCs) labeled with gold nanoparticles. Scale bar = 100 µm.

Laura Ricles, Seung Yun Nam, Stanislav Emelianov, and Laura Suggs (Dept. of Biomedical Engineering)

Cardiovascular diseases are the leading cause of death globally. Current research is focused on using stem cell-based therapy for cardiovascular diseases in order to promote neovascularization and rescue ischemic tissue. However, a major challenge to the development of these cellular therapies is the lack of efficient stem cell tracking methods in order to monitor the extent of cell engraftment, mechanisms of vascular regeneration, and participation and role of administered stem cells in vascular repair. To address these issues, we monitor and track mesenchymal stem cells (MSCs) in vivo following implantation. Specifically, we monitor blood vessel growth kinetics and functionin vivo using combined ultrasound/photoacoustic imaging in order to track MSCs labeled with gold nanoparticle contrast agents. In order to perform long-term tracking of MSCs, it is essential that gold nanoparticles are still localized within the cells over time and have not been sufficiently diluted due to cell division. ICP-MS provides a quantitative assessment of nanoparticle concentration within MSCs over time, thus providing us with information related to the feasibility of long-term cell tracking.

Figure 2. Spectroscopic photoacoustic imaging of nanoparticle labeled MSCs (green) injected into the lateral gastrocnemius. Skin (yellow) and oxygenated (red) and deoxygenated (blue) hemoglobin are also shown.

Figure 2. Spectroscopic photoacoustic imaging of nanoparticle labeled MSCs (green) injected into the lateral gastrocnemius. Skin (yellow) and oxygenated (red) and deoxygenated (blue) hemoglobin are also shown.

Figure publications:

  1. Ricles LM, Nam SY, Sokolov K., Emelianov SY, Sugs LI. 2011. Int J Nanomedicine 6: 407-16.
  2. Nam SY, Ricles LM, Suggs LJ, Emelianov SY. 2012. PLoS One 7: e37267

Quantitative Photoacoustic Imaging

Figure. Tissue histology qPA image of human squamous cell carcinoma overlain by bright-field optical image of iron-oxide nanoparticles.

Figure. Tissue histology qPA image of human squamous cell carcinoma overlain by bright-field optical image of iron-oxide nanoparticles.

Jason Cook, Wolfgang Frey, and Stanislav Emelianov

UT Austin Dept. of Biomedical Engineering

We designed a custom photoacoustic microscope with optical resolution to image and quantify nanoparticles in cells and thin tissue slices. Quantitative photoacoustic (qPA) imaging is based on the dependence of the photoacoustic signal with both the nanoparticle quantity and the laser fluence. Using multiple fluences, the effects of optical scattering were eliminated to enable accurate quantitation in turbid environments. To assess the accuracy of qPA imaging, nanoparticle-loaded macrophage cells were quantified and compared to ICP-MS. After validating the accuracy, qPA imaging was then used to image unstained histology slides from a nanoparticle-loaded xenograft human squamous cell carcinoma (Figure). Our results suggest that qPA imaging may be used in many biological nanoparticle applications including molecular targeting studies in vitro and in vivo, validation of clinical molecular imaging, and biodistribution studies for the assessment of toxicity.

Triblock Polymer System Designed with High Selectivity for Trivalent Actinides in Nuclear Waste

Triblock polymer system designed with high selectivity for trivalent actinides in nuclear waste

Triblock polymer system designed with high selectivity for trivalent actinides in nuclear waste

Lauren E. Avery, Brad J. Holliday
Holliday Research Group
Department of Chemistry and Biochemistry
The University of Texas at Austin

Spent fuel from nuclear reactors contains several radioactive isotopes with long lived half lives. With the advent of fast spectrum reactors many of these long lived products can be transmuted into shorter lived radioisotopes, creating more energy and less high level waste. The problem lies in the fact that the lanthanides and other fission products absorb neutrons in a reactor, quenching the reaction. Thus these products must be separated. Current liquid – liquid extraction techniques create large volumes of liquid waste and do not adequately discriminate between the actinides and lanthanides. A triblock polymer membrane is being developed to more efficiently separate these species. ICPMS is being utilized to determine the efficiency of metal extraction by the polymer system.

Evolution of the Mantle Below the Colorado Plateau, Southwestern U.S.

Grains of forsterite (green), of pyrope (red), and of a multitude of rock types. The mix of grains was scooped up from an anthill in northwestern New Mexico. Presumably the builders of the mound, harvester ants, were not sluggards, but promptly rebuilt as to be expected from a biblical proverb.

Grains of forsterite (green), of pyrope (red), and of a multitude of rock types. The mix of grains was scooped up from an anthill in northwestern New Mexico. Presumably the builders of the mound, harvester ants, were not sluggards, but promptly rebuilt as to be expected from a biblical proverb.

Doug Smith, UT Austin

Extraordinary serpentine-rich diatremes occur in the interior of the Colorado Plateau. These diatremes have a matrix of serpentinized ultramafic microbreccia; within the matrix are inclusions of  sedimentary rock, granite, granulite, eclogite, peridotite, and many other rock types. Discrete grains of forsterite, pyrope, and pyroxene are also scattered throughout the matrix. LA-ICP-MS is being used to analyze both the discrete forsterite grains and also forsterite grains in peridotite inclusions. One goal is to investigate how the mantle lithosphere below continents can be affected by subducting plates of oceanic lithosphere. Preliminary results establish that the discrete forsterite grains have significantly lower concentrations of Al, Cr, V, Ca, and Na than does most mantle olivine. These results confirm that the diatreme roots were in unusually cool mantle.

Trace Elements in Icelandic Rhyolite

TRACE ELEMENTS IN ICELANDIC RHYOLITEJason Keiser (MS Candidate – U. Mass)

I am using the full array of chemical analytical techniques to characterize individual basalt flows as well as felsic ash flows from an 8-9 million year old Oxnadalur bimodal volcanic complex in north-central Iceland.  Felsic eruptions in Iceland are rare, but can be quite voluminous.  Many studies have taken advantage of the great exposures to determine how felsic material can be generated in a setting otherwise dominated by mafic material, such as the oceanic crust.  The most common models have suggested fractional crystallization of a mafic source or partial melting of subsided extrusives as well as remelting of silicic segregations formed within the upper parts of solidifying basaltic intrusions beneath long lived central volcanoes.  Our goal is to combine major and trace element trends with REE trends and isotopic data to determine the role of fractional crystallization and partial melting in the evolution of the magma at the Oxnadalur complex.

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