Goldschmidt 2012 Conference Abstracts Combining U and Sr isotope tracers Elucidating the complex thermal and to evaluate water sources and mixing fluid history of Austurhorn Intrusive relations in freshwater and estuarine Complex: zircon elemental and wetlands isotopic geochemistry 1* 2 3 1 1* 1 1 2 J.B. PACES , J.Z. DREXLER , F. WURSTER , L.A. NEYMARK A.J. PADILLA , C.F. MILLER , T.L. CARLEY , J.L. WOODEN , 3 3 4 1 R.C. ECONOMOS , A.K. SCHMITT , C.M. FISHER AND J.M. U.S. Geological Survey, Denver, CO, USA, [email protected] 4 HANCHAR (*presenting author), [email protected] 2 U.S. Geological Survey, Sacramento, CA, USA, [email protected] 1Vanderbilt U., Earth & Environmental Sciences, Nashville, USA, 3U.S. Fish & Wildlife Service, Suffolk, VA, [email protected] [email protected] (*presenting author), [email protected], [email protected] Understanding wetland water supplies is important for managing 2Stanford U.-USGS MAC, SHRIMP-RG Lab, Stanford, USA, these resources and determining habitat impacts due to climate [email protected] change or other anthropogenic activities. However, identifying 3U. of California–Los Angeles, Earth & Space Sciences, Los multiple sources and contributions is often difficult due to complex Angeles, USA, [email protected], [email protected] 87 hydrologic, biologic, and chemical processes. Combined δ Sr and 4Memorial U. of Newfoundland, Earth Sciences, St. John’s, Canada, 234 238 U/ U data from wetlands in NV and CA identified 3-component [email protected], [email protected] mixing patterns that were not easily recognized by other chemical approaches. Isotopes of Sr and U are particularly useful because they The Austurhorn Intrusive Complex (AIC), comprising large are relatively abundant, can be analyzed with high precision, may bodies of granophyre, gabbro, and a mafic-felsic composite zone, is have large differences between sources, and remain unchanged by Iceland’s best-studied intrusion (Blake 1966; Furman et al 1992a,b; geochemical processes such as evaporation and mineral Thorarinsson & Tegner 2009). However, despite widespread precipitation or biological fractionation. Mixing models form recognition of the value of zircon as a tracer of history and evolution distorted triangular nets that bound the data and allow contributions of its parental magma(s), zircon studies are notably lacking for the from each source to be estimated. AIC and other Icelandic plutons. Here, we present the first detailed Sources of water in wetlands on the Pahranagat National chronologic, elemental, and isotopic Icelandic plutonic zircon study. Wildlife Refuge (PNWR), NV consist of surface flow from high- The elemental compositions of AIC zircons generally form a volume springs from the regional carbonate aquifer and groundwater broad but coherent array which, for the most part, overlaps with that from local volcanic aquifers. Major ions and H-O-S isotopes are of zircons from Icelandic silicic volcanic rocks (Carley et al 2011). affected by evapotranspiration, mineral precipitation, and sulfate With some exceptions (see below), Ti concentrations range from 6- 87 234 238 reduction. However, δ Sr and U/ U are unaffected and indicate 25 ppm (Tizirc temperatures ~ 730-870°C), and Hf concentrations a 70:20:10 mixture for the irrigation source and a range of mixtures are low (<10,000 ppm, typical of Icelandic zircon). Epsilon-Hf

depending on location and water management practices (fig. 1A). values are constrained to +13±1, falling between εHf for Icelandic Variations in river water and tidal influence in the Sacramento- basalts from rift and off-rift settings. Similarly, δ18O values are San Joaquin Delta, CA, over the last 6,000 years were recorded by generally well-constrained at +3 to +4‰, consistent with Icelandic δ87Sr and 234U/238U in peat cores. Plants take up substantial magmatic zircon (Bindeman et al 2012) and suggesting dissolved Sr during growth, whereas redox reactions at the peat- contributions from hydrothermally-altered crust to the petrogenesis water interface causes immobilization of U dissolved in the water of the parental silicic magmas. Zircons from a high-silica column. Analyses of peat cores show coherent changes in space and granophyre are notable exceptions to the trends described above: a time, reflecting evolving mixtures of fluvial and seawater sources large portion fall well outside of the AIC elemental array, (fig. 1B). Contributions from hydraulic mine sediment with δ87Sr distinguished primarily by extreme Hf concentrations ranging >0.0 and 234U/238U activities ~1.0 are also apparent in peat-poor upward to 24,000 ppm (far higher than other analyzed Icelandic samples deposited between 1850 and 1963. zircon), along with generally higher U and Th and lower Ti (down to 2 ppm [~630°C], lowest for Iceland). Their δ18O values range from “normal” (+4) to extremely low (-6‰). Most of the elementally and isotopically unusual analyses are from CL-dark zones that display convolute and/or irregular zoning. We interpret these zones to reflect hydrothermal crystallization or recrystallization. Zircon U-Pb geochronology reveals that the AIC was constructed by two distinct major intrusive events, the first at 6.45±0.04 Ma (MSWD=1.3) and a second at 5.99±0.06 Ma (MSWD=1.17). Most ages in the older population are from silicic rocks, while most ages in the younger populations are from a dominantly mafic zone. We interpret the younger age to represent Figure 1: Three-component mixing models showing 10% intervals the intrusion of voluminous basalt, which partially reactivated and for water in the PNWR (A) and peat in the Sacramento-San Joaquin remobilized the host silicic material ~500k.y. after initial Delta (B). emplacement of the AIC.

Mineralogical Magazine | www.minersoc.org 2198 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Tracking the Parental Melt of Neodymium isotopic composition of Chromite Using Trace Elements South Pacific bottom water

1 * 1 from LA-ICP-MS: an Effective Tool KATHARINA PAHNKE , CHANDRANATH BASAK AND 2 for Chromite Provenance RAINER GERSONDE 1Max Planck Research Group for Marine Isotope Geochemistry, PAGÉ, PHILIPPE1*, BARNES SARAH-JANE1 Oldenburg, Germany ([email protected]) 1 Canada Research Chair in Magmatic Metallogeny, 2Alfred Wegener Institute, Bremerhaven, Germany Université du Québec à Chicoutimi, Québec, Canada, G7H 2B1; ([email protected]); ([email protected]) Neodymium isotope ratios in seawater are a useful tracer of water masses and marine biogeochemical processes, but our current Chromite is one of the first phases to crystallize in ultramafic - knowledge of the distribution of Nd isotopes in the ocean is limited mafic silicate melts, and can thus be used to study early magmatic by the number of available data. Large areas, particularly in the processes in volcanic and plutonic environments. A better Southern Ocean, remain unstudied. The international effort of the understanding of chromite crystallization is also of economic interest, GEOTRACES program to map the global distributions of trace since it constitutes the only source of primary Cr, and massive elements and isotopes in the ocean [1] is improving the basis for the chromitites can host important Platinum-Group Element (PGE) use of Nd isotopes as tracers of present and past processes and concentrations (e.g. UG2, Bushveld Complex). changes. In our ongoing work, we are studying the composition of Here we present water column and surface sediment Nd isotope 143 144 chromites, obtained by EMPA and LA-ICP-MS, to i) constrain it’s ratios ( Nd/ Nd, expressed in HNd notation) from the Pacific role in the fractionation of certain elements (e.g. Os, Ir, Ru, Sc, Ga, sector of the Southern Ocean collected during R/V Polarstern Ni, Co, …) during early magmatic processes (i.e. fractionation of Ru expedition ANTXXVI-2. Deep and bottom waters in the southwest by komatiitic chromite [2, 3]) and ii) investigate the nature of the Pacific within the Antarctic Circumpolar Current (ACC) have an

parental melt involved in the formation of chromitite in both oceanic isotopic composition of HNd = -9, the characteristic isotope and continental settings. Using this approach, we have shown a clear signature of the ACC in the South Pacific and Atlantic [2, 3]. At a similarity between the geochemical signature of chromite from station south of the ACC and just north of the Ross Sea (69°S), ophiolitic podiform chromitites and chromite from the primitive bottom waters with the temperature-salinity properties of Antarctic boninites [1]. This study aims to constrain the nature of the primitive Bottom Water formed in the Ross Sea (RSBW), are more

melt involved in the formation of the Stillwater Complex chromitites radiogenic (HNd = -7). These values are consistent with the Nd which have a distinctive geochemical signature compared to isotopic composition of sediments and tills in the Ross Sea [4-6]), chromites from various primitive ultramafic - mafic melts (Fig. 1) suggesting an imprint of the Ross Sea signal on RSBW.

suggesting that none of these primitive magmas are involved in their We find similar HNd values in the authigenic ferromanganese formation. Also, these dissimilarities between the geochemical oxide fraction of surface sediments in the southeast Pacific at signature of chromite from the various lavas and from the Stillwater depths bathed by RSBW, suggesting the northward transport of the

Complex chromitites can be used to discriminate them from one Ross Sea HNd signal into the southeast Pacific. Our results show a another and thus be used as a provenance mineral. clear contribution of Antarctic Nd sources on the isotopic

composition of South Pacific bottom water and suggest that HNd can be used to trace the northward flow of RSBW into the southeast Pacific.

[1] GEOTRACES Science Plan (2006) SCOR. [2] Stichel et al. (2012) Earth Planet. Sci. Lett. 317-318, 282-294. [3] Carter et al. (2012) Geochim. Cosmochim. Acta 79, 41-59. [4] Farmer et al. (2006) Earth Planet. Sci. Lett. 249, 90-107. [5] van de Flierdt et al. (2007) Earth Planet. Sci. Lett. 259, 432-441. [6] Roy et al. (2007) Chem. Geol. 244, 507-519.

Figure 1: Composition of chromites from the Stillwater Complex chromitites compared to chromite from ultramafic-mafic volcanic rocks, including komatiite, boninite, and Hawaiian tholeiite, all of which have been normalised to the composition of the chromite from the MORB [1].

[1] Pagé & Barnes (2009) Economic Geology 104, 997-1018. [2] Pagé, Barnes, Bédard & Zientek (in press) Chemical Geology, 10.1016/j.chemgeo.2011.06.006. [3] Locmelis, Pearson, Barnes & Fiorentini (2011) Geochimica et Cosmochimica Acta 75, 3645-3661.

Mineralogical Magazine | www.minersoc.org 2199 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Controls on the formation and Boron contamination at the McIntyre 2+ 3+ 2- crystallization of Mg -Fe -SO4 tailings, Timmins, Ontario

1 1 type layered double hydroxides CORY PALIEWICZ *, MONA-LIZA C. SIRBESCU , 2 3 EDMOND H. VAN HEES , AND THOMAS SULATYCKY SUSANTA PAIKARAY* AND M. JIM HENDRY 1 Department of Geological Sciences, University of Central Michigan University, Earth and Atmospheric Sciences, Mt. Pleasant, MI, USA [email protected] (* presenting author) Saskatchewan, Saskatoon, SK, S7N5E2 Canada 2Wayne State University, Dept. of Geology, Detroit, MI, USA [email protected] 3 Introduction Goldcorp Inc., Timmins, Ontario, Canada

Layered double hydroxides (LDH) can play an important role in Anomalous concentrations of soluble boron of uncertain origin remediation of hazardous contaminants. Hydrotalcite-like (HTlc) occur in >40 year old mine tailings of the McIntyre-Hollinger LDH, also known as anionic clays, can be precipitated from mesothermal gold deposit. We seek to understand 1) the numerous divalent (M2+) and trivalent (M3+) cations along with distribution and movement of B in the tailings and 2) sources of interlayer anions (An-) where the nature, M2+/M3+ ratio and soluble B including: the wall-rock of the mineralization, the gangue concentation of ions, hydrothermal conditions, aqueous pH can minerals, and anthropogenic borax that might have been used to strongly control their formation and crystallization and, as such, smelt the gold ore. their applicability to act as sorbents, catalysts, pharmaceuticals, etc. To explore the distribution of boron within an area of about This study address such aspects using geochemical, spectroscopic, 100,000 m2, eight boreholes (e.g. H1) were drilled manually to a microscopic and diffractogram techniques. depth of ~9 m and sampled at ~0.15 or ~1 m intervals. The samples Materials and Methods were leached with deionized water at a sediment:water ratio of 1:3 HTlc formation was monitored using the coprecipitation and the filtered leachate was analyzed by ion chromatography. Boron synthesis method [1] at ambient temperature and pressure conditions is distributed heterogeneously with depth and distance from the edge and by varying the pH (7-13), M2+/M3+ ratio (0.5-2.5), cation of the tailings dam (Fig. 1). Boron contents correlate positively with addition rate (2-100 ml h-1), and cation concentrations (0.1-1.0 M) the ≤38 Pm grain size fraction, indicating that absorbtion onto silt- at a constant M2+/M3+ ratio (1.0), while assessing the degree of clay particles and/or low permeability result in B build-up. Tailings crystallinity over 30 days at three temperatures (22, 65 and 95 qC) near surface and at the margin of the dams are coarser and depleted and two drying temperatures (100 and 200 qC). The resultant solid in B. Ephemeral, efflorescent hydrous Mg-borate found along the phases were studied using X-ray diffraction, Raman and ATR- dam edge is consistent with an outflow of B along paths of high Infrared spectroscopy, and SEM and thermogravimetric analysis. permeability. Results and Discussion W E H1 Formation of HTlc was favored at pH t 9 and M2+/M3+ t 0.75 B (ppm) 2- 2- 324 with both CO3 and SO4 as interlayer anions. The latttice H2 250.0 H3 parameters c and a determined at pH 13 and M2+/M3+=2.5 was ~23.5 Å and ~3.1 Å, respectively. Although HTlc formation was not greatly 187.5 influenced by the reagent addition rate and M2+-M3+ concentrations, 125.0 slow addition appeared to inhibit development of d(110) plane 319 representing poor ‘a’ crystallographic development, while slow 62.5 addition and lower M2+-M3+ concentrations facilitated slightly better crystallization. This may be explained by better nucleation and the 0.0 lack of availability of elevated concentrations of cations [2]. The degree of crystallinity was observed to increase after ageing above sea level Elevation 314 for 30 days at room temperature (RT, 22r2 qC), increasing the 0 50 100 150 hydrothermal temperature to 95 qC within 1 day and increasing the Distance (m) drying temperature to 200 qC. The crystallization started lowering Figure 1: W-E cross-section of B (ppm) distribution and proposed after 5 days and 1 day at 65 and 95 qC hydrothermal treatment, discharge paths to edge of the dam ~20 m west of H1. respectively. The unusual B contents in the McIntyre tailings might originate Conclusions from altered basaltic wall-rock with B contents <3000 ppm. 2+ 3+ Preliminary observations suggest increasing pH, M /M ratio, However, the erratic character of the anomaly suggests that the 2+ 3+ low M -M concentrations, and a slow mixing rate facilitate HTlc release of B from the disposal of crushed, borax-fluxed slag into the formation and enhance its crystallinity. Although HTlc is likely to tailings is also possible. Fresh tourmaline in the tailings sediment develop crystallinity at RT upon prolonged exposure, elevated and relatively soluble gangue minerals (anhydrite, calcite, siderite, hydrothermal temperatures may adversely impact its structure. etc.) with <6 ppm B (via laser ablation ICP-MS) cannot account for [1] Cavani et al. (1991) Catal Today 11, 173-301. the amount of soluble B encountered. [2] Hickey et al. (2000) J Mater Sci 35, 4347-4355.

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Nature of fluids in the deep mantle A critical evaluation of TEX86 (>300km) inferred from a carbon and derived sea surface temperatures in nitrogen micro-analytical study of a the Paleogene

single ultra-deep diamond from RICHARD D. PANCOST1* , KYLE TAYLOR1 AND CHRIS HOLLIS2 Kankan, Guinea 1Organic Geochemistry Unit, School of Chemistry, The Cabot 1* 1 1 1 Institute, University of Bristol, UK, [email protected] (* M. PALOT , D.G PEARSON , R. STERN , T. STACHEL presenting author) 1 Department of Earth and Atmospheric Sciences, University of 2 GNS Science, Lower Hutt, New Zealand Alberta, Edmonton, Canada, [email protected] (* presenting author). The application of glycerol dialkyl glycerol tetraether (GDGT) based

sea surface temperature proxies (e.g. TEX86) has brought about major

The nature of the deep mantle, especially the transition-zone, is advances in our understanding of Cenozoic climate. However, TEX86 a topic of very broad interest to solid Earth geochemists and approaches yield very high temperatures at high latitudes during geophysicists. Data on actual samples from this region are Paleogene hyperthermals, and the resulting low latitudinal extremely scarce. Diamonds are derived from the base of the temperature gradients challenge our understanding of the physical

lithosphere down to the lower mantle (>660km) and provide a climate system. Here, we examine existing TEX86 data and revisit the

unique opportunity to sample this region of critical rheological and modern calibration dataset. A comparison of TEX86 SST estimates to chemical changes in the Earth. In order to evaluate the nature of those derived from oxygen isotopes or Mg/Ca ratios of well fluids percolating through the transition zone, we present the first preserved ‘glassy’ planktonic foraminifera reveals a strong carbon and nitrogen isotope micro-analytical study of a deep- correlation between foraminiferal and GDGT-based approaches, but

diamond (Kankan, Guinea) by Secondary Ion Mass Spectrometry the latter are 4-6°C warmer. We have also compared TEX86 SST (SIMS). This diamond contains a single CaSiO3-walstromite estimates from shelf sea settings to associated continental mean air

inclusion, presumed to represent retrogressed former CaSiO3- temperatures (MAT) derived from soil bacterial GDGTs (the perovskite and hence indicative of an ultra-deep (lowermost MBT/CBT index). Again, the two approaches exhibit a strong transition zone to lower mantle) paragenesis. The large size of the correlation but with the former yielding 4-6°C warmer temperatures. L diamond allows to investigate variability in the diamond growth Intriguingly, SSTs derived from the recently proposed TEX86 medium along detailed traverses. Combined C-N isotope and N approach are lower and consistent with foraminifera-based abundance measurements allow us, for the first time, to place strong approaches and MBT/CBT derived MATs. constraints on the nature of the parental fluid for an ultra-deep We also developed SST records from multiple sites in the SW diamond. Pacific, in order to place hyperthermal SST estimates into a longer- Carbon isotopic compositions show a small but systematic term Paleogene context. Our estimates indicate that sea floor and sea decrease of δ13C values from the core to the rim of the diamond. surface temperatures increased by 10°C or more from late Paleocene δ15N is negatively correlated with δ13C, whereas nitrogen (18 to 23°C) to early Eocene times (30-32°C). MBT/CBT-derived abundances show a positive correlation. These co-variations in G13C- MATs broadly parallel the SST trends, but with 4-6°C lower values δ15N-[N] are consistent with open system isotopic fractionation throughout the entire sequence. These records suggest that elevated where the isotopic and elemental evolution of the fluid is related to high southern latitude SSTs are reproducible at multiple sites and do diamond crystallisation. The speciation of carbon and nitrogen of the document the relative long-term Paleogene climate evolution fluid precursor of this deep diamond may be constrained through recorded by benthic foraminifera and inferred from faunal and floral modelling of these co-variations. Such modelling indicates diamond assemblages.

growth from a reduced, CH4-bearing fluid, with nitrogen behaving Combined, these two lines of evidence indicate that high latitude compatibly. Due to uncertainities in δ15N, we cannot constrain EECO temperatures were indeed significantly higher than those of + whether nitrogen was present in the fluid phase as N2 or the NH4 . today, but they also suggest that the specific estimates could be as Although the origin of the diamond forming fluid (subducted or much as 4-6°C too warm. There are multiple explanations for this, mantle material) is still a matter of debate, these results have but one possibility is an oceanographic and/or ecological control on

fundamental implications for the fO2 in the deep mantle and the deep the GDGT assemblages exported to sediments, an explanation that volatile cycle of the Earth. could also explain the unexpected offset between SSTs derived from L TEX 86 compared to other calibrations. Specifically, the offset in both ancient and modern settings is associated with low GDGT-2 to GDGT-3 ratios. In contrast to previous inferences, those low ratios are not limited to cold regions and in fact are associated with shallow water settings and upwelling zones. We propose that this reflects depth-dependant differences in GDGT distributions that are

manifested differently in the various TEX86 calibrations, with some reflecting primarily shallow water signatures and others reflecting integration over a greater depth range.

Mineralogical Magazine | www.minersoc.org 2201 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Zinc isotopic variations among Carbonaceous material associated ordinary chondrites with apatite in the Chassigny

1,* 1 RANDAL C. PANIELLO , FREDERIC MOYNIER , meteorite from Mars

1 1,2* JEAN-GABRIEL FRABOULET DOMINIC PAPINEAU 1Dept of Earth and Planetary Sciences, Washington University, St. 1 Department of Earth and Environmental Sciences, Boston College, Louis, MO, USA, [email protected] (* presenting author) Chestnut Hill, United States, [email protected] 2 Geophysical Laboratory, Carnegie Institution of Washington, Zinc is a moderately volatile element that may be capable of Washington DC, United States. movement among minerals or even volatization during thermal metamorphism, despite the absence of partial melts. We obtained Following the biologically important elements is key for the search for life beyond Earth. Carbon and Phosphorous are two high-precision isotopic measurements of zinc by MC-ICP-MS 1,2] fundamental biological elements for all life on Earth, and are found from a suite of 70 ordinary chondrites (OCs), in order to study their throughout Earth's geological record in minerals like graphite and variation across the metamorphic range. The samples included 23 apatite. Associations between disordered carbonaceous material and LL-, 26 L-, and 21 H-chondrites; 26 of the 70 were non-Antarctic apatite are reported here for the first time in an extraterrestrial falls, 3 were non-Antarctic finds, and 41 were Antarctic finds. Serial sample. These mineral-pairs were found in the Chassigny meteorite leachates were obtained from the LL3.0 Semarkona, and magnetic which is an olivine cumulate rock from the Martian mantle. Raman spectra and microspectroscopic images show the presence of (metal), silicate and sulfide fractions were separated in three samples disordered carbonaceous material associated with hydroxylapatite- in order to determine the contributions of each phase to the total zinc maskelynite inclusions in olivine grains. Optical and electron budget. Three whole rock samples were broken into several smaller microscopy suggest that there is a petrogenetic connection between pieces and each was measured in order to determine the small scale carbonaceous material, hydroxylapatite, maskelynite, Ni-rich homogeneity of the zinc isotopes. pyrrhotite, Cr-rich spinel, orthopyroxene, and olivine. Carbonaceous 66/64 material is often associated with hydroxylapatite in fields of dozens The δ Zn (reported against the JMC-Lyon standard) for the of 2-30 micron-sized maskelynite inclusions in olivine, which is entire suite, combined with previous data [3,4] generally fell within a interpreted here, on the basis of the Raman D- and G-bands, to narrow range, with a mean of -0.04±0.13 (2se). There was no represent precipitation from low-temperature hydrothermal fluids. significant difference measured between Antarctic and Non-Antarctic Focused Ion Beam (FIB) was performed to micro-fabricate samples. Isotopic fractionation showed a slight trend across OC targets of these mineral associations. Analyses by TEM-EDS show that hydroxylated apatite grains a few microns in size are embedded subtypes LL

[1] Moynier et al. (2006) GCA 70 6103-6117, [2] Moynier et al. (2011) 5, 297-307, [3] Luck et al. (2005) GCA 69 5351-5363, [4] Moynier et al. (2007) 71 4365-4379.

Mineralogical Magazine | www.minersoc.org 2202 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Calcrete on Everglades tree islands: How large is the subducted water human occupation or tree growth? flux? New constraints on mantle 1* 2 3 JEANNE PAQUETTE , MARIE GRAF , GAIL L. CHMURA , CAMERON regassing rates 4 1* 1 BUTLER RITA PARAI AND SUJOY MUKHOPADHYAY 1 Earth & Planetary Sciences, McGill University, Montreal, Canada, 1Harvard University, Cambridge, MA, USA, *[email protected] [email protected] (* presenting author) 2 Montreal, Canada, [email protected] Constraints on the long-term cycling of water between the mantle 3 McGill University and Global Environmental and Climate Change and exosphere (i.e., the atmosphere, oceans and crust) are critical to Centre, Montreal, Canada, [email protected] our understanding of mantle rheology, the structure and style of 4 Bioresources Engineering, McGill University, Ste-Anne-de-Bellevue, mantle convection [1], and the volatile budget of our planet. Volcanic Canada, [email protected] water output from the mantle is offset by input at subduction zones in the form of chemically-bound water in subducting slabs. Water New geochemical and petrographic analyses shed light on the origin released from subducting slabs at high pressures and temperatures is of the "enigmatic" carbonate layer perched within the soil of some outgassed to the exosphere by arc and back-arc volcanism. Any water Everglades tree islands. For some time, archaeologists [1, 2] have noticed entrained in the mantle wedge or retained in the slab beyond depths the presence a 45-70 cm thick calcareous layer in the islands of of magma generation constitutes a return flux of water to the interior, terrestrial vegetation perched just a meter above the flooded wetlands of often referred to as the post-arc subducted water flux. Estimates of the Everglades. This layer, impenetrable without heavy equipment, had the magnitude of the total input flux of water at subduction zones and been interpreted as a topographic high in the underlying karst platform. the magnitude of the return flux beyond arcs into the deep mantle Schwadron's archeological excavations of selected islands revealed soil have been used to discuss long-term regassing of the mantle [2-5]. and artifacts below the carbonate layer and a midden just above the karst However, these estimates vary widely, and some are large enough to platform [3]. As Schwadron had not observed artifacts in the layer, she have reduced the volume of water in the global ocean by a factor of interpreted it as a hiatus in midden/peat deposition. The cultural age of two over the Phanerozoic. artifacts above and below the layer suggested that it formed ~3800-2700 In light of uncertainties in the initial hydration state of cal yr BP, a period corresponding to a broad scale climate change subducting slabs, magma production rates and mantle source water recognized in the southeast U.S. and associated with cultural changes contents, we use a Monte Carlo simulation of the deep Earth water from the Late Archaic (Archaic = 9k to 3.5k BP) to Early Woodland cycle to set limits on long-term mantle regassing. The simulation is culture [4]. constrained by reconstructions of Phanerozoic sea level change, Another model [5] proposed for the development of the calcrete which suggest that ocean volume is near steady-state, though a sea layer required no major climate perturbation, only the occurrence of level decrease of up to 360 m may be supported [6-8]. We find that distinct wet and dry seasons where evapotranspiration from vegetation previous estimates of both the input flux of water into subduction might result in the reprecipitation of calcium carbonate around roots zones and the return flux beyond depths of magma generation are within the soil profile. frequently too large to reflect long-term water cycling. Our results [9] Our most recent investigations indicate that a major component of suggest a limited extent of serpentinization in subducting lithospheric the hardened layer is detrital rather than pedogenic. Most calcareous mantle. For a near steady-state exosphere (0-100 m sea level fragments show textures of an oolitic limestone with isopachous decrease), we find an average return flux of 1.4–2.0 x 1013 moles/yr, meteoric cements. Their oomoldic porosity is typical of the local corresponding to 2-3% serpentinization in 10 km of lithospheric underlying Pleistocene bedrock (Miami Limestone). Pedogenic features mantle. For a maximum sea level decrease of 360 m, the average (needle-fiber calcite, root casts) in the surrounding soil indicate that the return flux is 3.5 x 1013 moles/yr, corresponding to 5% limestone fragments have been dissolving in the peaty soil profile. serpentinization in 10 km of lithospheric mantle. Our estimates of the Phreatic acicular calcite cements fill pores in phosphatic bone fragments return flux of water past arcs are up to 7 times lower than previously throughout the layer, enhancing their preservation and fixing phosphorus suggested [2-5; 9]. The net imbalance between our estimates of the within the tree island soil. return flux and the mantle-derived output flux gives an upper limit This provides evidence for layer development that requires neither bulk mantle regassing rate of 24 ppm/Ga. Furthermore, our results abandonment nor climate change. The question remains as to whether indicate that while water in the mid-ocean ridge basalt source may be these limestone fragments were pulled up from a karstic, rubble-covered accounted for by recycling of water carried in subducted slabs, bedrock by fallen trees or if they were left by human occupants. If recycled slab water contents may not be high enough to account for vegetation simply enhanced the pedogenic cementation into cohesive the water contents of the ocean island basalt (OIB) source, such that calcrete layers of limestone fragments left by early human occupants, some fraction of OIB source water appears to be juvenile. these layers might have value as stratigraphic markers. [1] Crowley et al. (2011) EPSL 310, 380-388. [2] Schmidt and Poli [1] Mowers (1972) Fla. Anthropol. 25, 129-131. (1998) EPSL 163, 361-379. [3] Hacker (2008) Geochem. Geophys. [2] Carr (2002) Tree Islands of the Everglades, 187–206. Geosyst. 9, 24. [4] Rüpke et al. (2004) EPSL 223, 17-34. [5] van [3] Schwadron (2006) Antiquity 80. Keken et al. (2011) JGR Solid Earth 116, B01401. [6] Vail et al. (1977) AAPG Memoir 26, 63-97. [7] Haq et al. (1987) Science 235, [4] Kidder (2010). Anthropol. Papers AMNH, 93, 23-32. 1156-1167. [8] Hallam (1992) Phanerozoic Sea Level Change. [9] [5] Graf, Schwadron, Stone, Ross, Chmura (2008) Eos Trans. AGU 89, Parai and Mukhopadhyay (2012) EPSL 317-318, 396-406. 117-124.

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1, * 1 1 MADHAVI PARIKH , TAMAR BARKAY , NATHAN YEE 1* 1 1 2 G. PARIS , J.F. ADKINS , A.L. SESSIONS , S.A. CROWE , C. 1 2 3 2 School of Environmental and Biological Sciences, Rutgers JONES , D.A. FOWLE , D.E. CANFIELD University, New Brunswick, NJ, USA (*correspondence: [email protected]) 1 Division of Geological and Planetary Science, California Institue

of Technology, Pasadena CA, USA Background 2Institute of Biology, Nordic Center for Earth Evolution, University Syntrophic microbial consortia composed of anaerobic bacteria of Southern Denmark, Odense, Denmark are able to catalyze electron transfer reactions that a single organism 3Departement of Geology, University of Kansas, Lawrence KS, USA cannot [1]. Syntrophy is a community-level process that involves *corresponding author: [email protected] interspecies exchange of metabolites between organisms. Cooperative exchange of electrons and hydrogen in microbial Lake Matano, Indonesia, is one of the ten deepest lakes in the communities is known to play an important role in the fermenation world and the largest modern ferruginous basin [1,2]. Despite a low

of complex natural organic matter to CO2 and CH4. Currently, the thermal gradient, a persistent chemocline at 100 m isolates surface -1 role of syntrophy in the the reduction of crystalline iron oxides is waters with low sulfate concentrations (<25 μmol.l ) and sulfate- free deep waters [1]. The chemical properties of Lake Matano make poorly understood. Here we examined the reduction of crystalline it a prospective analogue for the ferruginous Archean ocean and it iron oxides by an anaerobic microbial consortium during has been used to study the potential role of anoxygenic phototrophic fermentative growth. We present evidence that the rapid iron Fe(II)-oxidizing bacteria in the synthesis of Banded Iron Formations reduction rates are enabled by syntrophic interactions between the [1] as well as carbon cycling in ferruginous settings [2]. Dissolved bacteria that form this consortium. sulfate is completely removed between 100 and 150 m by sulfate Materials and Methods reduction. However, very low concentrations of sulfide are observed A consortium composed of two microorganisms was cultivated in the Fe(II)-rich chemocline because of efficient removal by precipitation of FeS [2]. from a sediment core collected from the United States Department To explore the biogeochemical cycling of sulfur in Lake of Energy Field Research Center (FRC) in Oak Ridge Tennessee. Matano, we investigate the isotopic composition of sulfur in sulfate 34 The consortium consists of a fermenting Clostridium species and a (δ Sso4) from a water profile spanning the surface and chemocline hydrogen-oxidizing bacterium belonging to the family of the lake. Because of the low concentrations of sulfate make the Vellionellaceae. Iron reduction experiments were conducted to analysis of the sulfur isotopic composition of SO4 with conventional evaluate the ability of this consortium and pure culture to reduce BaSO4 precipitation is nearly impossible because it would require a huge amount of sample. Here, we use a recently developed method goethite, hematite and ferrihydrite during fermentation of peptone. 34 for δ Sso4 analysis using the ThermoScientific ‘Neptune’ At periodic time points, samples were collected and analysed for multicollector inductively-coupled plasma mass spectrometer (MC- Fe(II) and hydrogen production by ferrozine assay and gas ICPMS). This method allows us to measure the isotopic chromatography, respectively. PCR amplification of the 16S rRNA composition of sulfur from trace sulfates in natural samples. Sulfate genes and denaturing gradient gel electrophoresis (DGGE) analysis was extracted from lake waters using a cation-exchange resin were performed to determine the dominant member of the microbial (Dionex AG50X8) and analyzed on the Neptune as Na2SO4. community. Furthermore, using a Cetac ‘Aridus’ as an introduction system Results and Discussion decreases isobaric interference due to O2 isotopologues on the isotopes 32S, 33S and 34S and 32S-H on 33S. We will also explore the When grown on fermentable substrates, the microbial triple isotope variability of this unique system using our new MC- consortium reduced goethite (α-FeOOH) and hematite (Fe2O3) with ICPMS method. specific log reduction rates of -3.1 and -3.3 pmol m-2 h-1 cell-1, Reproducibility of δ34S better than 0.2 ‰ (1σ) is achieved by respectively. DGGE analyses indicated that the Clostridium species running 5 to 20 nmol of sulfate (1 to 10 ml of waters from Lake was the dominant member in the consortium during the reductive Matano). Results will provide new constraints on the fractionation dissolution of crystalline iron oxides. In pure culture, the of sulfur isotopes in sulfate-poor water, thus helping to constrain our understanding of sulfur cycling during Archean times in a Clostridium species was able to reduce ferrihydrite, but it reduced ferruginous ocean. goethite and hematite at 4 to 5 times lower rates than the intact

consortium. Finally, we show that the Clostridium species produces [1] Crowe, Jones, Kastev, Magen, O’Neill, Sturm, Canfield, Haffner, hydrogen during fermentation, and that the growth of the Mucci, Sundby and Fowle (2008), Proceedings of the National Vellionellaceae partner is stimulated by the presence of H2 gas. Academy of Science 105, 15938-15934 These results suggest that interspecies hydrogen transfer may play a [2] Crowe, Kastev, Leslie, Sturm, Magen, Nomosatryo, Pack, key role in controlling the rates of crystalline iron oxide reduction Kessler, Reesburgh, Roberts, Gonzalez, Douglas, Haffner, Mucci, Sundby and Fowle (2011), Geobiology 9, 61–78 by fermentative microbial communities.

[1] Summers et al., (2010) Science, 330, 1413-1415.

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A biogeochemical orientation study in 'HODPLQDWLRQRIVXEFRQWLQHQWDO Mo skarn deposits, Jecheon distict, OLWKRVSKHUHEHQHDWKWKH.RUHDQ Korea 3HQLQVXODHYLGHQFHIURPXOWUDPDILF

1* 1, 2 1 JI-YOUNG PARK , JONG-NAM KIM , AND HYO-TAEK CHON [HQROLWKVLQ&HQR]RLFEDVDOWV 1* 2 1Seoul National University, Department of Energy Resources KYE-HUN PARK , YONG-SUN SONG Engineering, Seoul, Republic of Korea, [email protected] 1Pukyong National University, Earth Environmental Sciences, Busan, (*presenting author), [email protected] Korea, [email protected] (* presenting author) 2Korea Resources Coportation, Seoul, Republic of Korea, 2Pukyong National University, Earth Environmental Sciences, Busan, [email protected] Korea, [email protected]

A biogeochemical orientation survey was conducted in the The Cenozoic alkali basalts are widely scattered over Korea and vicinity of Mo skarn deposits in Jecheon district in Korea. A skarn often carry spinel lherzolite xenoliths, indicating that the zone of over 600 m length is hosted in Ordovician carbonate lithospheric thickness beneath Korea does not reach deep enough to sediments and is adjacent to both Jurrassic and Cretaceous felsic the garnet lherzolite stability field. Interestingly enough, the spinel intrusives. Molybedenum occurs in fracture zones within the skarn peridotite xenoliths from Korean peninsula can be divided into two and in disseminated form. The skarn ore minerals consist mainly of groups based on their geochemical and Sr, Nd, Hf and Pb radiogenic scheelite, molybdenite, galena, and chalcopyrite. The total samples isotopic compositions, i.e. enriched group and depleted group. The of rocks, soils, and plants – daimyo oak leaves/branches (Q. former xenoliths have enriched isotopic compositions very similar dentata) and sargent cherry leaves (P. sargentii) – were collected to their host basalts but show refractory nature of major element from the target area and barren control area, and analyzed by ICP- compositions with quite low CaO and Al2O3 contents indicating their MS. Each of three sampling lines was designed to cross the orebody derivation from the old Paleoproterozoic subcontinental at 30 m spacing intervals. The soil samples (n=36/10, target/control) lithospheric mantle beneath the Korean peninsula. In contrast, the collected from the target area show higher values of Mo (<0.1~38.7 latter have depleted isotopic compositions similar to mid-oceanic ppm) compared with those from the control area (<0.1~3.2 ppm ridge basalts with apparently fertile major element compositions of Mo). In all of the plant samples (n=108/30, target/control), Mo relatively high CaO and Al2O3 contents similar to present day concentration from the target area (2.7~95 ppm in Q. dentata asthenospheric mantle indicating that such asthenosphere-derived leaves, 0.2~99.1 ppm in Q. dentata branches, and 1.7~69 ppm in P. materials may have replaced the lithosphere quite recently. In sargentii leaves) is 3~7 times higher than that from the control area general, the host basalts show isotopic compositions similar to the (1.9~10.3 ppm in Q. dentata leaves, 0.9~6.3 ppm in Q. dentata enriched xenoliths, indicating genetic link between them. branches, and 2~5 ppm in P. sargentii leaves). The variation patterns Simple geobarometric calculations indicate that the depths of of Mo in plants are similar to those in soils, suggesting a origination of the xenoliths are in average of ca. 75 km, suggesting corresponding Mo anomaly and contrast between soils and plants. that the maximum thickness of the subcontinental lithosphere would The values of Mo in soils and plants are strongly correlated. The not exceed such depth quite much. On the contrary, the crustal biological absorption coefficient (BAC) of Mo in the plants is evolution of the Korean peninsula seemingly started since the generally high (Q. dentata leaves = 15 and Q. dentata branches/P. Archean, at least some part of it, suggesting normal lithospheric sargentii leaves = 9.1). The three plant organs have high thickness of 150 km or greater. Such lithospheric thickness of the possibilities to be used as indicators for the biogeochemical Korean peninsula significantly thinner than expected is quite similar prospecting of Mo. to the case of North China Craton having lithospheric thickness of ca. 80 km in average, suggesting significant delamination of the lithospheric mantle in a depth scale of a few tens of kilometers during the past geologic time. Such delaminations may have occurred after the continental collisional events of Paleoproterozoic and early Mesozoic, suggested by wide occurrences of igneous and metamorphic events during the 1.9-2.0 Ga and also during the early Mesozoic throughout the Korean peninsula.

Mineralogical Magazine | www.minersoc.org 2205 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Adsorption of organics and Magnesium isotope fractionation nanoparticles at mineral-water during bacterial mediated carbonate interfaces. precipitation

1* 1 1* 1 2 STEPHEN C. PARKER , THOMAS V. SHAPLEY , RUNLIANG I. J. PARKINSON , C.R. PEARCE , T.K. POLACSEK , C.S. 1,2 1 3 2 ZHU , AND MARCO MOLINARI COCKELL , M.M. GRADY 1Department of Chemistry, University of Bath, Bath BA2 7AY, 1Department of Environment, Earth and Ecosystem, The Open United Kingdom, [email protected] (* presenting author) University, Walton Hall, Milton Keynes, MK7 6AA, UK 2Key Laboratory of Mineralogy and Metallogeny, Guangzhou 2Department of Physical Sciences, The Open University, Walton Institute of Geochemistry, Chinese Academy of Science, Hall, Milton Keynes, MK7 6AA, UK Guangzhou, 510640, China 3School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Edinburgh, EH9 3JZ, UK We present our recent work, developing and applying *[email protected] complementary computational methods to gain atomistic insights into systems comprising mineral-organic-water interfaces. The Magnesium is the eight most abundant element in the Earths research scheme involves the use of ab initio including van der crust, and the fourth most abundant species in seawater. As such it is Waals interactions and experimental data to validate rigid-ion or an essential component of life, with pivotal roles in the generation polarizable potential models which are then applied within energy of cellular energy as well as in plant chlorophyll [1]. The bio- minimization (EM) and classical molecular dynamics (MD) geochemical cycling of Mg is associated with mass dependant techniques. This robust approach covers the evolution of systems of fractionation (MDF) of the three stable Mg isotopes, 24Mg, 25Mg different sizes and for different lengths of time allowing the and 26Mg[1]. The largest MDF of Mg isotopes has been recorded in evaluation of structures and dynamic properties. carbonates, with foraminiferal tests displaying the lowest δ25Mg and The focus of our attention is on layered minerals including δ26Mg compositions[2]. metal hydroxides, clay minerals and organo-clays interacting in the Bacterial carbonate precipitation is known to have occurred in aqueous environment. The presence of organo-compounds (OCs) modern and ancient Earth surface environments[3,4], with and nanoparticles (NPs) which can impact on the environment by cyanobacteria having a dominat role in carbonate formation during entering the food chain, can also disrupt the mineral/water interfaces the Archean. In this study, we aim to better constrain the extent to affecting the physico-chemistry of aqueous systems. which Mg isotope fractionation occurs during cellular processes, Several examples are discussed including adsorption and and to identify when, and how, this signal is transferred to transport of OCs on montmorillonite and pyrophyllite and of carbonates. To quantify these effects we have performed fullerene on brucite in the presence of water capturing their biologically-induced carbonate precipitation experiments using atomistic features and helping to interpret experiments. The several bacteria strains. The organisms are grown under defined CLAYFF [1] and GAFF [2] or CVFF [3] force fields are applied to organic and Ca/Mg ratios in artificial seawater, and under the clay surfaces and OCs and NPs respectively. Flexible TIP3P [4] temperature controlled conditions that promote carbonate and shell models of water are used in solvated systems. Interatomic formation. Carbonate spheres of ~100 microns diameter are potentials are tested against DFT calculations using VASP [5]. EM produced, which are amenable to SEM, EMP and Mg isotopic and MD employ the METADISE [6] and DL_POLY [7] codes. analysis by MC-ICP-MS. In order to compare our experimental data Our results indicate that the interplay between the adsorption, to natural samples we will present Mg isotope data for modern and which is surface-site as well as counter-ion-site dependent, and the ancient stromatolites, which are laminated carbonates produced by transport of OCs and NPs on soil clay significantly disrupts the micro-organisms. Our new data will shed light on tracing bacterial structure of the mineral-water interface [8,9] which has previously signals in the geological record. been shown to extend well above both mineral and nanoparticle surfaces [10]. Finally we find that the energy of adsorption is [1] Young & Galy (2004). Rev. Min. Geochem. 55, p197-230. [2] strongly affected by the inclusion of the van der Waals interactions Pogge von Strandmann (2008). Geochem. Geophys. Geosys. 9 DOI:10.1029/2008GC002209. [3] Castanier, et al. (1999). Sed. within the DFT simulations and of the polarizability terms in the Geol. 126, 9-23. [4] Cacchio, et al. (2003). Geomicrobiol. J. 20, potential models within classical techniques. 85-98.

[1] Cygan et al. (2004) J. Phys. Chem. B 108, 1255-1266. [2] Wang et al. (2004) J. Comp. Chem. 25, 1157-1174. [3] Dauber- Osguthorpe et al. (1988) Proteins: Structure, Function, and Genetics 4, 31-47. [4] Cornell et al. (2006) J. Am. Chem. Soc. 117, 5179-5197. [5] Kresse & Furthmuller (1996) Phys. Rev. B 54, 11169-11186. [6] Watson et al. (1996) J. Chem. Soc., Faraday Trans. 92, 433-438. [7] Smith & Forester (1996) J. Mol. Graph. 14, 136-141. [8] Zhu et al. (2011) Adv. Mater. Res. 233-235, 1872- 1877. [9] Zhu et al. (2011) Environ. Sci. Technol. 27, 6504-6510. [10] Spagnoli et al. (2011) Langmuir 27, 1821-1829.

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1* MICHELE PARRINELLO levels: a new Precambrian paradigm 1ETH Zurich and Università della Svizzera Italiana, Lugano, emerging? Switzerland, [email protected] (*presenting author) 1* 1 2 C.A. PARTIN , A. BEKKER , N.J. PLANAVSKY , B.C. 3 4 5 6 GILL , C. LI , V. PODKOVYROV , A. MASLOV , K.O. 7 2 2 KONHAUSER , G.D. LOVE , T.W. LYONS Frontiers in Computational Geochemistry The experimental study of systems under condition of high 1University of Manitoba, Geological Sciences, Winnipeg, Canada, temperature and pressure provide a considerable challenge. Accurate [email protected] (* presenting author), and reliable computer simulations could be of great help in this area [email protected] of science. However to reach this goal considerable technical 2University of California, Riverside, Earth Sciences, U.S.A., difficulties need to be overcome. We present a number of methods [email protected], [email protected], [email protected] developed in our laboratory that greatly help towards reaching this 3Virginia Tech, Geosciences, Blacksburg, U.S.A., [email protected] goal. We apply these techniquese to study the phase diagram of 4China University of Geosciences, Key Laboratory of Biogeology materials, structural phase transition and the nucleation of crystals and Environmental Geology, Wuhan, China, [email protected] from solution. 5Russian Academy of Sciences, Institute of Precambrian Geology and Geochronology, St. Petersburg, Russia, [email protected] 6Russian Academy of Sciences, Zavaritskii Institute of Geology and Geochemistry, Ekaterinburg, Russia, [email protected] 7University of Alberta, Earth and Atmospheric Sciences, Edmonton, Canada, [email protected]

The Precambrian atmosphere and oceans are traditionally thought to have undergone a progressive, gradual increase in oxygen content after ~2.4 Ga [1]. This gradual transition from anoxic to oxidizing conditions is assumed to have occurred in two incremental steps, one at the beginning, and one at the end of the Proterozoic Eon. Emerging data require a change to this paradigm. Enrichments of the redox-sensitive element uranium in organic matter-rich shales through time shows that the Earth’s surface oxidation had a more dynamic and unexpected history. Archean shales show very low [U] (<10 ppm, average of 3.8 ppm), consistent with a large U sink in anoxic oceans. The Great Oxidation Event (GOE) is accompanied by a rapid increase in maximum [U], up to 60 ppm, which likely reflects the onset of strong oxidative continental weathering releasing soluble U and expansion of oxygenated environments in the oceans. The initial rise of atmospheric oxygen ~2.4-2.32 billion years ago was followed by a dramatic decline to less oxidizing conditions during the Middle Proterozoic, beginning after the cessation of the Lomagundi carbon isotope excursion at ~2.05 Ga, when [U] in shales returned to near-to-crustal levels (average of 3.2 ppm). The subsequently established, steady-state low-oxygen mode persisted for nearly one billion years, terminating with a second oxygenation event in the latest Neoproterozoic, when [U] in shales demonstrate a dramatic increase, up to 94 ppm, by 551 Ma. Utilizing the ubiquitous geological shale record, U concentrations reveal Earth’s dynamic path to its presently well-oxygenated atmosphere-ocean system, with unprecedented temporal resolution. We will present evidence for a precipitous rise and (previously unrecognized) fall in atmospheric oxygen early in the Proterozoic, which is in direct contrast to conventional models predicting a unidirectional oxygen rise. With this new paradigm in mind, future models will need to reexamine the links between the co-evolution of life and the chemical composition of the Precambrian oceans.

[1] Kump, L. (2008) Nature 45, 277-278.

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[email protected], (* presenting author) , Fe oxides are transported as suspended sediment in rivers [email protected] towards the oceans and act as a major source of iron for primary 2 producers [1]. During this journey, the redox environment changes JNR Resources, Saskatoon, Canada, [email protected], 3 drastically, from dark, reducing environments in the subsurface, to Cameco Corporation, Saskatoon, Canada, light, oxidizing environments in fresh and marine surface waters and [email protected], [email protected], sediments. Here, we are interested in exploring whether our and [email protected] others’ recent findings of Fe(II)-Fe(III) electron transfer and atom exchange occur under more marine-like redox conditions, where Unconformity-associated uranium deposits from the Paleo- to Fe(II) can be structurally bound in a solid phase, and dissolved Mesoproterozoic Athabasca Basin in Saskatchewan, Canada, include Fe(III) may be present as a sparingly soluble aqueous species the largest high-grade U ore deposits in the world. Most of the complexed with ligands of various types [2]. deposits are located at the unconformity between the sedimentary In reducing environments, the reaction of Fe(II) and Fe(III) basin and the Archean to Paleoproterozoic basement. Graphite minerals is becoming widely recognized to be more complex than and/or carbonaceous matter (CM) are found in the basement, often simply surface sorption of Fe(II). Rather, a complex process concentrated along structures which can be identified as involving sorption, Fe(II)-Fe(III) electron transfer, and often electromagnetic (EM) conductors, and potentially could act as a extensive recrystallization both with and without secondary mineral reductant that could trigger deposition of uranium. transformation is beginning to emerge [3]. Whereas there is The focus of this study is the Dufferin Lake Zone, an extensive compelling evidence for oxidation of sorbed Fe(II) by structural “conductive” block along the trend of the Virgin River Shear Zone in Fe(III) in Fe minerals, such as goethite, magnetite, hematite, and the south-central Athabasca Basin. The Centennial uranium deposit ferrihydrite, it is unknown whether electron transfer will occur occurs along this trend, although it appears to be located away from between sorbed Fe(III) and structural Fe(II) in Fe(II) minerals. It is the interpreted EM conductor at depth. The significance of this also unclear whether significant Fe exchange will occur between observation is that typical exploration strategies of trying to identify aqueous Fe(III) and Fe(II) minerals. mineralized traps along EM conductors may not always be relevant. We synthesized several Fe(II) containing minerals, such as In order to address this issue, this study aims to examine, in detail, a magnetite, mackinawite, and siderite from 56Fe and reacted it with drill hole fence of metamorphosed basement rocks that at depth aqueous 57Fe(III) complexed with various Fe ligands. Mössbauer contain variable proportions of graphite, either in structures or in spectroscopy is specific to 57Fe, and thus by synthesizing the pelitic gneisses, but appear to have lost some or all of their graphite underlying oxide from 56Fe, we can turn off the signal from the solid, as the unconformity is approached. and isolate whether the aqueous 57Fe(III) is reduced. In addition, we A combination of analytical techniques will be used to are using an enriched Fe isotope tracer approach, similar to our characterize the textural relationships, crystallinity, and type of previous work [4] to determine whether significant Fe atom exchange CM/graphite in the pelitic gneisses and shear/fault zones at various occurs between the bulk solids and aqueous phase. depths below the unconformity. Lithogeochemistry, fluid inclusion and stable isotope analysis, and synchrotron techniques will be [1] Jickells et al. (2005) Science 308, 67-71 utilized to provide constraints on the chemical variability between [2] Rickard and Luther (2007) Chemical Reviews 107, 514-562. graphite-bearing and graphite-depleted rocks, and the likely [3] Gorski and Scherer (2011) Aquatic Redox Chemistry, 1071, 315- composition of fluids that may have removed graphite. For example, 343 was the graphite removed by fluids moving along the unconformity [4] Handler et al. (2009) Env Sci Tech 43, 1102-1107 or the underlying weathered rocks soon after the basin formed, or was it removed by fluids more directly involved in space and time with uranium mineralization, such as a highly corrosive basinal brine. Initial petrographic observations show much hetereogeneity and complexity in the textural relationships and type of CM/graphite in the pelitic gneisses and shear/fault zones at depth. Further work will first analyze these rocks, and then the rocks within the graphite- depleted zone, prior to establishing the link between the two zones. Did the graphite or its breakdown products act as the reductant for uranium deposition?

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BENJAMIN H. PASSEY* AND GREGORY A. HENKES Department of Geoscience, University of Calgary, Calgary, Alberta, Department of Earth and Planetary Sciences, Johns Hopkins Canada, [email protected] University, Baltimore, MD 21218 (*[email protected]) Nucleation difficulty can lead to overstepping of metamorphic Carbonate clumped isotope thermometry can potentially reveal reactions. Overstepping can result in multiple reactions being information about the passage of inorganic carbon through the shallow- and mid-crust on its journey to and from the Earth’s deep energetically possible, both stable and metastable. The only criterion interior. The ordering of rare isotopes of C and O into the same that has to be satisfied is that each possible reaction lowers the free carbonate groups creates ‘multiply-substituted’ isotopologues such energy of the system. Overstepping can therefore lead to a ‘cascade 13 18 16 as Ca C O O2 (~67 ppm natural abundance). These isotopologues effect’, in which several reactions involving the same reactant phases are surrounded in the mineral lattice by isotopically normal 12 16 isotopologues such as Ca C O3 (~982,000 ppm), and solid-state proceed simultaneously in a small temperature interval. Two diffusion of C and O over unit cell distances will act to create and different types of cascade effect are recognized. The first, termed remove multiple substitutions. This short length scale of diffusion the ‘Bushveld-type’ in respect of its documentation in the Bushveld leads to the possibility of cooling rate-dependent carbonate clumped isotope closure temperatures in the ~100-300 °C range, much lower aureole (Waters & Lovegrove, J Met Geol, 2002), arises from than traditional mineral oxygen isotope closure temperatures, and a delayed nucleation of a product phase and subsequent production of range useful for studying shallow- and mid-crustal processes. We that product phase from several different reactants. In the Bushveld determined Arrhenius parameters for solid-state reordering of C-O example, the low-entropy chloritoid to staurolite/andalusite bonds in calcite through a series of laboratory heating experiments. We present a closure temperature equation for carbonate clumped reactions were overstepped to the point that they were overtaken in isotope thermometry analogous to Dodson’s solution first order terms of reaction affinity by high-entropy muscovite+chlorite- loss [1], where the closure temperature is a function of cooling rate consuming reactions. Nucleation of staurolite and andalusite by the and the Arrhenius parameters for solid-state C-O bond reordering. latter reactions eliminated the principal kinetic barrier to the The sensitivity of closure temperature to cooling rate is sufficient for order of magnitude inference of cooling rate, provided the progress of the overstepped chloritoid-consuming reactions, such Arrhenius parameters of the studied minerals are well known. The that several staurolite- and andalusite-producing reactions ran in inferred cooling rate of Carrara marble is ~ 3 °C per 10 ka, which is parallel in a small temperature interval, creating a reaction cascade. within error of independent estimates of the cooling history of the Fluid release accompanying initial reaction may also have Alpi Apuane metamorphic core complex. contributed to the cascade effect by facilitating dissolution of chloritoid. The second type of cascade effect, termed the ‘Nelson- type’ in respect of its documentation in the Nelson aureole (Pattison et al., J Met Geol, 2009; 2011) involves a catalytic trigger related to the sudden build-up or influx of fluid in rocks that have overstepped two or more stable reactions. The result is simultaneous production of different product phases from the same reactant minerals. In the Nelson aureole, the clustering of the garnet, staurolite and andalusite isograds, contrary to their predicted wider spacing according to equilibrium thermodynamics, and the textural evidence that each of

Figure 1: Carbonate clumped isotope closure '47 and closure these porphyroblasts formed from reaction of the matrix with no temperatures as a function of cooling rate. Solid curved line is the evidence of the predicted consumption of the earlier-formed best-estimate closure temperature relationship based on kinetics porphyroblasts, suggests the simultaneous operation of several observed in the laboratory for an optical calcite. The curved dashed chlorite-consuming reactions. Once the nucleation-related barriers lines reflect uncertainty in Arrhenius parameters propagated through the closure temperature model. Star and horizontal dashed line show to initial garnet formation were overcome, fluid was released into the mean '47 value of Carrara marble analyzed in four different the grain boundary network, enhancing rates of intergranular laboratories [2]. CDES: ‘Carbon dioxide equilibrium scale’ [2]. transport and possibly further nucleation. This created a positive

[1] Dodson (1973) Contrib. Mineral. Petrol. 40, 259-274. feedback and a vigorous reaction interval involving production of [2] Dennis et al. (2011) GCA 75, 7117-7131. several porphyroblast phases from the same matrix reactants.

Mineralogical Magazine | www.minersoc.org 2209 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Paleoceanographic interpretation of Petrology of syn-orogenic S-type the light rare earth elements leucogranites (Damara orogen; 1 2 GENNA M. PATTON , PAMELA A. MARTIN , EMILIA Namibia) – Constraints from Sr, Nd 3 3 SALGUIERO , AND ANTJE H.L. VOELKER and Pb isotopes 1 University of British Columbia, Vancouver, Canada, 1* 1 2 ANDRE PAUL , STEFAN JUNG , ROLF L. ROMER AND 3 [email protected] (* presenting author) ANDREAS STRACKE 2Earth and Environmental Sciences, IUPUI, Indianapolis, IN, United 1 Mineralogisch-Petrographisches Institut, Universität Hamburg, States ([email protected]) Germany, 3 Unidade Geologia Marinha, Laboratorio Nacional de Energia e [email protected] (*presenting author) Geologia, Amadora, Portugal ([email protected], [email protected] [email protected]) 2 GeoForschungsZentrum, Potsdam, Germany 3 Institut für Mineralogie, Westfälische Wilhelms Universität, The rare earth elements (REE) in sea water have been used as Münster, Germany indicators of the modern oceanic and paleoceanic environments. The Nd-isotopic composition (εNd) of ferromanganese crusts and The northern central zone of the Damara Orogen (Namibia) consists 4 nodules successfully record water mass changes integrated over 10 of metasedimentary rocks, Pan-African syn- to late-tectonic and 105 years; fossil fish teeth and debris pinpoint water mass granites, and rare basement gneisses. Leucogranites of S-Type changes through the Cenozoic, though also with low temporal character with ages of ca. 510-515 Ma appear to be little resolution due to the scarcity of fish remains [2; 3]. Records of much higher temporal resolution have been produced from the εNd fractionated although the two suites have high K2O (5.7-7.3 wt%), of bulk sediment leach, and over glacial-interglacial timescales [4]. Th (30-74 ppm), and U (3-13 ppm) abundances and moderately high Isolating the εNd of seawater from lithogenic contamination, but relatively constant Rb/Sr ratios (2.7-4.4). High light rare earth however, is problematic. Detrital contaminants are much more elements but variable heavy rare earth elements concentrations easily removed from planktonic foraminifera and therefore may be result in high and variable Lan/Ybn ratios ranging from 16 to 98, more representative of a seawater signal [1]. The phase in which the suggesting involvement of garnet during crustal melting. The εNd is associated with foraminiferal calcite is of critical importance for the paleoceanographic interpretation. In addition to Nd, the full granites have, relative to other syn-tectonic S-type suites from the 87 86 sequence of rare earth elements can speak to diagenetic indicators Damara orogen, more unradiogenic Sr/ Srinit. ratios (0.7095- and bottom-water conditions in which the authigenic signal is 0.7140 vs. 0.7150-0.7340). HNd values range from -4.5 to -6.5; the acquired. Studies of coupled planktonic benthic REE comparison majority of values being similar to those from syn-tectonic S-type allow for clear indications of diagenetic overprinting. Here, we granites (εNd -3.0 to -5.5) and match those found in present data from the Iberian Margin that demonstrate coherent, metasedimentary xenoliths (εNd -5.0 to -7.0) from these syn- diagenetic signals indicative of environmental conditions associated with climate signals. Also, we present data generated using X-ray tectonic S-type granites. The Pb isotopic composition of acid- absorption near edge structure analysis that help to identify fine- leached feldspar is broadly similar to the one of metapelitic scale spatial distribution of high concentrations of REE and also the xenoliths in Damaran syn-tectonic S-type granites suggesting that oxidation state of redox sensitive cerium. With a combination of the leucogranites are derived from isotopically similar metapelitic paleorecords and different analytical approaches, we can begin to rocks. Zircon saturation temperatures are high for crustally derived identify the distinct phases of the REE and as a result, the granites, but well within the range commonly accepted for S-type paleoceanographic interpretation of these elements. granites (800-840°C). U-Pb monazite ages and Rb-Sr whole rock ages indicate that the leucogranites intruded simultaneously with the main peak of metamorphism. The heating event that promoted [1] Elmore, A., A. Piotrowski, and J. Wright (2011), Testing the extraction of past seawater Nd isotopic composition from North melting of fertile rocks at depth might have been subsidized by high Atlantic deep sea sediments and foraminifera. [2] Frank, M. (2002), heat productivity, which is also reflected in the elevated K, Th, and U Radiogenic isotopes: tracers of past ocean circulation and erosional abundances of apparently unfractionated granites, and crustal input, 40(1), 1001. [3] Martin, E., S. Blair, G. Kamenov, and H. Scher (2010), Extraction of Nd isotopes from bulk deep sea thickening during the Pan African orogeny. sediments for paleoceanographic studies on Cenozoic time scales. [4] Piotrowski, A., S. Goldstein, S. Hemming, and R. Fairbanks (2004), Intensification and variability of ocean thermohaline circulation through the last deglaciation, 225(1-2), 205-220.

Mineralogical Magazine | www.minersoc.org 2210 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Lead isotopes in South Atlantic Characterization of Hg leaching seawater: insights on anthropogenic inputs and ocean circulation from the riverbank sediments of the

1* 1 1 1 South River, VA M. PAUL , T. VAN DE FLIERDT , D. WEISS , M. REHKÄMPER 1* 1 1 1Imperial College, London, UK (*[email protected]) KRISTA PAULSON , KRISTA DESROCHERS , CAROL PTACEK , 1 1 2 DAVID BLOWES , BLAIR GIBSON , RICHARD LANDIS , JAMES Trace elements and their isotopes play an essential role in DYER2, NANCY GROSSO2

biological processes in the marine environment. Like many 1 micronutrient elements, lead (Pb) is mainly supplied to the remote Earth and Environmental Sciences, University of Waterloo, parts of the ocean by atmospheric deposition. Unlike nutrients, Waterloo, ON, Canada however, its behaviour in seawater is dominated by passive *[email protected] (* presenting author) scavenging onto particles. As Pb is one of the elements which is 2E.I. du Pont de Nemours and Company, Wilmington, DE, USA heavily influenced by anthropogenic contamination, its isotope composition in seawater can give us key information on (i) A large portion of Hg found in the natural environment anthropogenic vs. natural sources affecting the modern oceans, and (ii) the movement of water masses within the global oceans [1,2] originates from sediment and soils that are transported and dispersed To better exploit the potential of Pb isotopes for research in by runoff and erosion. The associated particle-facilitated transport marine geochemistry, we have developed a new method for accurate depends on the mineralogy and pore-water chemistry of the sediment high precision analyses of Pb isotopes in seawater. The methodology and can impact the bioavailability and toxicity of Hg [1]. In this involves pre-concentration of Pb using Mg(OH)2 co-precipitation [3] study, freshwater river sediments and bank soils that contained and further purification by ion exchange chromatography on two successive columns of AG1X8 100-200 resin. Samples are then elevated concentrations of Hg were collected along two vertical loaded on single Re filaments with a mixture of silica gel and transects perpendicular to the South River, Virginia, USA. The South phosphoric acid. The isotopic analyses are carried out on a TRITON River system accumulated Hg from industrial processes along the 204 207 TIMS instrument at Imperial College London, using a Pb/ Pb river during the early part of the 20th century. The sediment samples double spike for the correction of instrumental mass fractionation [4]. were analysed using a variety of techniques, including sequential Using our newly installed and tested technique, we analyzed several depth profiles of seawater from the South Atlantic Ocean chemical extractions and synchrotron-based X-ray absorption collected in the framework of the UK-GEOTRACES program. More spectroscopy (XAS). Column transport experiments were conducted precisely, the samples are derived from a transect along 40°S to evaluate Hg leaching from the sediment and bank soils. Specific between Cap Town (South Africa) and Montevideo (Uruguay). The issues addressed are the extent that Hg leaches from the sediment key feature of this remote and little studied part of the Atlantic Ocean under varying geochemical conditions, which develop in the is a high productivity band in an otherwise nutrient-poor region, which may be due to a number of potential sources of nutrients. Our frequently inundated riverbanks, and the role of particle-facilitated lead isotope data will help to constrain anthropogenic and natural and colloidal transport of Hg from the bank sediments. dust inputs from both South Africa and South America and their Sediment samples from both transects contained both soluble (up migration within the vertical water column. In addition, intermediate to 32%) and less soluble forms of Hg (up to 94%), as determined by and deep water analyses will reveal the presence of Southern Ocean sequential chemical extractions [2]. Micro-XAS analysis produced and North Atlantic waters. spectra that were consistent with the mineral phase metacinnabar

[HgS]. Column transport experiments conducted with the two

sediment samples that contained the elevated concentrations of Hg

indicated nearly identical leaching of Hg. These sediments contained

similar concentrations of total Hg (280 Pg g-1 total Hg for a sample

collected from the unsaturated zone near the top of the river bank and

187 Pg g-1 for a sample collected from an elevation just above the [1] Reuer, M.K and D.J. Weiss (2002) Phil. Trans. of the Royal Society of London Series A: Math., Phys. and Engineering Sciences base flow level of the river), but contained markedly different 306 (1801), 2889-2904 fractions of extractable Hg. The effluent concentrations of Hg [2] Von Blanckenburg, F. and H. Igel (1999) EPSL 169 (1-2), 113- initially ranged from 1.5 to 3 μg L-1 for the 0.45 μm filter fraction for 128. both columns and the unfiltered samples ranging from 2 to 5.3 μg L-1. [3] Wu, J. and E.A. Boyle (1997) Anal. Chem. 69, 2464-2470 After 80 pore volumes, the concentrations decreased. Calculated [4] Hamelin B., Mahnes G. et al. (1985) GCA 49, 173-182 cumulative masses of Hg leached from the sediments reached a plateau at < 2% of the water soluble fraction of Hg, suggesting a diminishing availability of Hg for leaching under saturated flow conditions. These results suggest that there is potential for leaching of elevated concentrations of Hg in both dissolved and particulate forms, that the mass available for leaching under saturated conditions appears to much less than predicted using standardized sequential extraction analyses, and that a portion of the Hg had remained in a relatively stable sulfide phase even after many decades of atmospheric exposure.

[1] Lowry et al. (2004) Environ. Sci. Technol. 38, 5101-5111. [2] Bloom et al. (2003) Anal. Chim. Acta. 479, 233-248.

Mineralogical Magazine | www.minersoc.org 2211 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Sorption models for complex Deciphering the Cenozoic Tl isotope materials – modeling approaches and record of marine ferromanganese data requirements crusts – new evidence from

TIMOTHY E. PAYNE adsorption experiments 1* 2 Australian Nuclear Science and Technology Organisation, Lucas CAROLINE L. PEACOCK , SUNE G. NIELSEN , LAURA E. 3 4 5 Heights, Sydney, Australia, [email protected] WASYLENKI , ELLEN M. MOON AND MARK REHKÄMPER

1School of Earth & Environment, University of Leeds, Leeds, UK, Surface complexation models (SCMs) can be applied to [email protected] (* presenting author) complex geologic materials such as sediments and soils using 2Dept. of Geology and Geophysics, Woods Hole Oceanographic various approaches, which are generally variants on either the Institution, Woods Hole, MA, USA, [email protected] component additivity (CA) or generalised composite (GC) models 3Dept. of Geological Sciences, Indiana University, Bloomington, IN, [1]. The CA approach involves modeling the sorption of a trace metal USA, [email protected] (or radionuclide) by additively combining sorption models for the 4ANSTO Minerals, Autralian Nuclear Science and Technology individual mineral components of a soil. The GC approach is more Organisation, NSW, Australia, [email protected] generic, but is often parameterised using bulk properties such as the 5Dept. of Earth Science & Engineering, Imperial College London, specific surface area (SSA) or ion exchange capacity. London, UK, [email protected] These approaches are demonstated using data for cobalt adsorption on complex materials from Australian field sites. The GC modeling estimated the number of sorbing sites from the measured Thallium stable isotopes, recorded in authigenic marine BET surface area (assuming a site density of 2.31 sites/nm2 [2,3]). A ferromanganese crusts, may provide new constraints on past changes simplified CA model that conceptualised the surface sites as having in environmental conditions, the Earth’s carbon cycle, and their equivalent sorption properties to amorphous Fe oxide was also impact on global climate.[1-3] Specifically, the Cenozoic Tl isotope moderately successful in explaining the pH dependence of the Co curve shows a pronounced evolution of Tl isotope composition 205 sorption data sets. This example demonstrates the basic utilility and around the Palaeocene-Eocene boundary, from ~ 6 H Tl at 55 Myr 205 205 predictive capability of these modeling approaches. However, as to ~ 12 H Tl at 45 Myr (where H Tl is the deviation of the 205 203 with literature examples of SCMs for complex materials, it does not Tl/ Tl ratio of a sample from the NIST SRM 997 Tl isotope fully test the underlying assumptions. These outcomes raise standard in parts per 10000).[2] After this pronounced shift, the Tl questions about the uniqueness and general applicability of these isotope composition of crusts appears to have changed little over the modeling approaches [3]. last 40 Myr, with a globally uniform, modern signature of ~ 13 205 A principal requirement to further develop the CA modeling H Tl. Despite the compelling appearance, the record provided by approach is adequate models for trace metal sorption on component Tl isotopes (and other heavy-metal stable isotope systems) is not mineral phases of complex environmental sorbents and conclusive straightforward because the temporal shift in isotope composition 205 demonstration of their role in each sample. Similarly, the GC may reflect either variability in the H Tl value of seawater, or approach requires experimental measurement of sorption data on a changes in the conditions that govern incorporation of the element range of complex samples of differing mineralogy and SSA under into the structure of the ferromanganese minerals. Furthermore, 205 various conditions. Given that it is relatively straightforward to modern crusts are ~ 19 H Tl (or ~ 2 ‰) heavier than the experimentally study sorption and measure SSA, it might be contemporaneous seawater, and combined with their globally expected that numerous sets of trace-metal sorption data for uniform signature this implies there is an equilibrium stable isotope complex samples having a range of properties would be available. fractionation between Tl in seawater and the Tl incorporated into However, while individual studies typically report sorption data crust minerals. across a range of chemical conditions (pH, ionic strength, etc), the To improve our understanding of the Tl isotope record experiments often involve only a single solid sample (or limited preserved in crusts it is important to develop a detailed number of samples). Consequently, a significant constraint on characterisation of how Tl is sequestered by ferromanganese obtaining the required data for establishing relationships between minerals, and a quantitative and mechanistic understanding of any sorption and SSA (or other soil properties) is that few literature data stable isotope fractionation that occurs during this process. Here sets report sorption as a function of SSA (or mineralogy) for a we present the results of novel experimental work that combines number of different solid phases. Thus, there is an urgent need for molecular-level, X-ray absorption spectroscopy with stable isotope more experimental sorption work with a range of sorbent samples. analyses of Tl sorbed to ferromanganese minerals, as a function of time, temperature, pH and ferromanganese mineralogy. Based on [1] Davis et al. (1998) Environ. Sci Technol. 32, 2820-2828 the experiments, we have constrained the mechanistic basis for Tl [2] Dzombak and Morel (1990) Surface complexation modeling – enrichment and stable isotope fraction in ferromanganese crusts, and hydrous ferric oxide. John Wiley and Sons, New York, 393pp. we will discuss the effect of the experimental parameters on the [3] Payne et al. (2009). Applied Radiation and Isotopes. 67, 1269- fractionation factor between simulated seawater and solid minerals. 1276. [1] Rehkämper et al. (2004) Earth Planet. Sci. Let. 219, 77-91. [2] Nielsen et al. (2009) Earth Planet. Sci. Let. 278, 297-307. [3] Baker et al. (2009) Geochim. Cosmochim. Acta 73, 6340-6359.

Mineralogical Magazine | www.minersoc.org 2212 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Mechanisms of tetrahedral iron Novel insights on a traditional proxy: formation in ferrihydrite observed via soft x-ray spectroscopy Combining the stable and radiogenic 1* 2 1 Sr isotope systems to characterise DEREK PEAK , JAMES J. DYNES , ROBERT GREEN , AND TOM 2 Z. REGIER continental weathering

1 1* 1 University of Saskatchewan, Saskatoon Canada, CHRISTOPHER R. PEARCE , IAN J. PARKINSON , KEVIN W. 2 3 4 [email protected] (*presenting author) BURTON , EMILY I. STEVENSON , JÉRÔME GAILLARDET , 5 6 [email protected] ROBERTA L. RUDNICK , JOSH WEST AND DOUG E. 2 6 Canadian Light Source, Saskatoon, Canada, HAMMOND [email protected] 1 [email protected] Department of Environment, Earth and Ecosystems, CEPSAR, The Open Universtiy, Walton Hall, Milton Keynes, MK7 6AA, UK Introduction 2Durham University, Durham, UK Ferrihydrite is a poorly crystalline ferric hydroxide 3Oxford University, Oxford, UK nanomineral. It rapidly transforms to more stable crystalline 4Institut de Physique du Globe de Paris, Paris, France minerals such as goethite (FeOOH) in the lab, but it is metastable in 5University of Maryland, College Park, USA natural systems and found as persistant coatings as well as discrete 6University of Southern California, Los Angeles, USA particles. Its high reactivity and widespread occurrence make its *Presenting and corresponding author: [email protected] structure important for geochemists, life scientists (as ferritin), and environmental engineers. However, disagreement among researchers The radiogenic strontium isotope system (87Sr/86Sr) is one of remains as the structure of this enigmatic material. The central the most established methods for tracing continental weathering, as question in the structural debate is whether iron in ferrihydrite is subtle, but resolvable, differences in 87Sr/86Sr ratios enable the Sr purely octahedral, or if tetrahedral ferric iron is present. Recent content of water, vegetation and humans to be linked to specific studies proposing tetrahedral iron in this phase have proposed that it locations and lithologies[1]. On a global scale, shifts in weathering may form via condensation of keggin-type aqueous polymers similar processes control the composition of the oceans, with differences to aluminum, but these have never been directly observed for iron. in the relative flux of silicate and carbonate material over geological Accordingly, the objective of our study was to monitor the timescales reflected in the 87Sr/86Sr ratio of marine carbonates[2]. precipitation of ferrihydrite from forced hydrolysis of ferric Unlike the radiogenic system, variations in stable Sr isotopes chloride in situ using high resolution Fe L-edge XANES (G88/86Sr) are controlled by mass dependent processes, with the main spectroscopy of solutions in a flow through liquid cell. Spectra driver of fractionation thought to be incorporation into carbonates[3]. were collected using both Fe partial yield and the newly developed The combined application of the 87Sr/86Sr and G88/86Sr systems IPFY approach for self absorption-free bulk XAS measurements. therefore has the potential to differentiate source variations from The precipitation process was followed from pH 1 to 7.5, and results other weathering processes, providing a valuable method for from these aqueous measurements were compared to air dried assessing strontium transport through the critical zone. samples prepared at the same pH. STXM measurements of wet and This study presents isotopic data from both Sr systems at dried ferrihydrite were also collected for comparison. various points in the hydrological cycle; 87Sr/86Sr and G88/86Sr values Our results demonstrate clearly that L-edge XANES are from glacial ice, precipitation, river water, dust and bedrock are used extremely sensitive to shifts in ligand field that accompany to constrain the sources and cycling of Sr on the continents. hydrolysis of metals and coordination changes. There is clear Samples dominated by atmospheric Sr transport typically display evidence that tetrahedral iron is present in air-dried samples, but that lower G88/86Sr compositions than equivalent surface waters, and are the in situ measurements are consistent with only octahedral iron. thought to be influenced by anthropogenic contamination effects. This suggests that the dominant mechanism for tetrahedral iron in River water samples dominated by surface run-off have 87Sr/86Sr and ferrihydrite may be physical dehydration rather than a chemical G88/86Sr values that depend on the underlying lithology: Continental reaction. This has enormous implications for natural systems, silicate terrains typically have G88/86Sr values within 0.10 ‰ of the where wetting and drying cycles are expected to strongly influence global riverine mean (0.34 ‰), whereas rivers draining carbonate mineralogy and basaltic terrains (i.e. those with 87Sr/86Sr ratios <0.7100) show considerably greater G88/86Sr variation, ranging from 0.10 ‰ to 0.86 ‰. Differences are also observed within individual drainage basins and between wet and dry flow regimes, confirming the sensitivity of the stable Sr system to fractionation processes during weathering and transport. The findings of this study are compared to other isotopic weathering proxies, and the implications for the future application of the Sr weathering proxy are discussed.

[1] Bentley (2006) J. Arch. Meth. Theory 13, 135-187. [2] McArthur et al. (2001) J. Geol 109, 155-170. [3] Krabbenhöft et al. (2010) GCA 74, 4097-4109.

Mineralogical Magazine | www.minersoc.org 2213 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Mineral, fluid and gas interactions Tetraether lipids of Archaea in under CO2 storage conditions – the paleoceanography: Unresolved role of SO2, NOX, and O2 questions and new directions 1,2* 2 1,2 2 1* J. PEARCE , D. BIDDLE , S. GOLDING , V. RUDOLPH AND ANN PEARSON 1,3 D. KIRSTE 1Harvard University, Department of Earth and Planetary Scienes, 1Cooperative Research Center for Greenhouse Gas Technologies Cambridge, MA, USA, [email protected] (* presenting 2University of Queensland, Brisbane, Australia, [email protected] author) (* presenting author), [email protected], [email protected], [email protected] 3Simon Fraser University, Vancouver, Canada, [email protected] Abstract Thaumarchaeota [1, 2], formerly known as Marine Group I

Co-contaminant gases such as SO2, NOX, and O2 are present in Crenarchaeota, are believed to be the primary source of the gas streams from power stations and oxy fuel power plants. Storage ubiquitous glycerol dialkyl glycerol tetraether lipids (GDGTs) found

of CO2 streams containing co-contaminants significantly reduces in the environment. GDGTs, including the unique compound capture costs however they may have significant physical and crenarchaeol, are abundant in marine and terrestrial aquatic chemical impacts on well materials, reservoir and cap rocks when in environments, in sediments and soils, and over at least an 85°C

contact with formation water. Geochemical modelling of SO2 co- temperature range from the polar ocean to hydrothermal springs. injection indicates formation of sulphuric acid and lowered Experiments on pure cultures, enrichment mesocosms, and

formation water pH compared to pure CO2 injection resulting in empirical correlations for marine sediments (TEX86; [3]) all show a increased mineral dissolution in the near well bore, and possible positive relationship between environmental temperature and the precipitation of minerals such as ankerite and dawsonite downstream number of cyclopentyl or cyclohexyl rings contained within the with a decrease in porosity and injectivity.[1] However modelling GDGT structure. The TEX86 paleotemperature proxy has been is hampered by a lack of experimental data at carbon storage applied across a large temporal range of geologic events and to

conditions for reactions involving co-contaminants SO2, O2 or NOX.. sediments of widely varying depositional and diagenetic history. In this context a new experimental apparatus has been Evaluating whether such broad applicability is widely robust requires constructed to reproduce in situ carbon storage temperature and answers to a number of lingering questions about: (1) the

pressure conditions for mineral – fluid –scCO2 – co-contaminant physiological mechanism governing the number and distribution of gas reactions, with periodic sampling of fluids and gases for these types of rings; (2) the degree to which microbial community analysis. structure influences the TEX86 relationship, including the extent to Experimental results and geochemical modelling of the which environmental Euryarchaeota also produce GDGTs; (3) the dissolution of pure mineral phases siderite, labradorite and illite in mechanism that transfers the TEX86 signal to marine sediments; (4)

CO2 saturated brines of high (150 g/l NaCl) and low salinity at the extent to which this signal is modified via diagenesis, in-situ representative reservoir conditions (80 °C, 200 bar) will be production, or sediment redistribution; (5) the taxonomic, presented. Recent work on far from equilibrium siderite dissolution ecophysiological, and evolutionary significance of the cyclohexyl

at up to 100°C and ~50 bar CO2 shows increased dissolved iron at ring-containing compounds, crenarchaeol and its regioisomer; and pH below 5 owing to proton promoted dissolution (PPD).[2] (6) the fidelity of empirical temperature correlations based on core- Labradorite dissolution is expected to be incongruent with enhanced top sediments. I will review these questions with a focus on the release of sodium, calcium and aluminium over silica at our promise and prospects offered by isotopic approaches, which to date temperature conditions.[3] Labradorite dissolution may be expected have remained underutilized. to decrease under saline conditions by comparison to feldspar

dissolution experiments in the absence of CO2.[4] The effect on References siderite at our conditions is less clear cut, however recently [1] Brochier-Armanet, C., Boussau, B., Gribaldo, S., and Forterre, P. (2008) Mesophilic crenarchaeota: proposal for a third archaeal Testemale et al. observed an order of magnitude decrease in the rate phylum, the Thaumarchaeota. Nature Reviews Microbiology 6, 245- constant for siderite dissolution at 100°C and 300 bar with the 252. -1 + addition of 1 mol kg NaCl resulting from competition of Na with [2] Spang, A., Hatzenpichler, R., Brochier-Armanet, C., Rattei, T., H+ affecting PPD.[4] Further experiments will include the co- Tischler, P., Spieck, E. et al. (2010) Distinct gene set in two contaminants O2 (5%) and SO2 (1%). Renard et al. observed different lineages of ammonia-oxidizing archaea supports the increased reactivity of carbonate and clay by up to a factor of 10 on phylum Thaumarchaeota. Trends in Microbiology 18, 331-340. [3] Schouten, S., Hopmans, E.C., Schefuss, E., and Damsté, J.S.S. addition of SO2 and O2.[6] With SO2 co-injection the lowered pH (2002) Distributional variations in marine crenarchaeotal membrane conditions are expected to increase mineral dissolution rates. lipids: a new tool for reconstructing ancient sea water temperatures? Earth and Planetary Science Letters 204, 265-274. [1] Xu et al (2007) Chem. Geol. 242, 319. [2] Golubev et al. (2009) Chem.Geol. 265, 13. [3] Carroll et al. (2005) Chem.Geol.217, 213. [4] Blake et al. (1999) Geochemica et Cosmochima Acta 63, 2043. [5] Testemale et al. (2009) Chem.Geol. 259,8. [6] Renard et al.(2011) Energy Procedia 1, 3283.

Mineralogical Magazine | www.minersoc.org 2214 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Development and application of LA- First record of Ediacaran iron ICP-MS in the geosciences: past, formations: Origin and present and future paleoenvironmental significance

1 1 1 1 1 1 N.J. PEARSON *, W.L. GRIFFIN AND SUZANNE Y. O’REILLY E. PECOITS *, N. R. AUBET , M. K. GINGRAS , S. W. 2 3 4 1 POULTON , A. BEKKER , G. VEROSLAVSKY AND K. O. ARC Centre of Excellence for Core to Crust Fluid Systems, 1 KONHAUSER Department of Earth and Planetary Sciences, Macquarie University, Sydney, NSW 2109, Australia 1University of Alberta, Edmonton, Canada, [email protected] [email protected] (*presenting author); (* presenting author) [email protected]; [email protected] 2Newcastle University, Newcastle upon Tyne, United Kingdom, [email protected] The rapid advances in in situ laser ablation (LA) inductively 3University of Manitoba, Winnipeg, Canada, coupled plasma-mass spectrometry (ICP-MS) and multicollector [email protected] (MC)-ICPMS have provided datasets in geochronology and 4Universidad de la República, Montevideo, Uruguay, geochemistry that have revolutionised our understanding of the [email protected] geodynamic Earth at all scales. The development and application of LA-ICP-MS continues to grow at a dramatic rate and in situ analyses It is widely believed that the Earth’s oceans became increasingly for elements and isotopic ratios are now performed routinely in oxygenated during the late Neoproterozoic, most notably after the numerous laboratories worldwide. Like other microbeam techniques end of the Marinoan glaciation approximately ׽635 million years LA-ICP-MS provides the benefit of high spatial resolution and ago. However, recent geochemical data for Ediacaran sediments produces data that can be interpreted in a microstructural context. suggest that some deep ocean basins were instead anoxic and The development of new LA-ICP-MS methodologies has been ferruginous [Fe(II)-enriched] throughout the Ediacaran and possibly enabled by advances in instrumentation in conjunction with studies into the Cambrian, suggesting a more complex global redox of the fundamental processes involved in ablation and in the ICP structure than previously envisioned. An apparent absence of (e.g. laser-induced elemental and isotopic fractionation, plasma Ediacaran iron formations (IF) presented a challenge to this loading, mass bias). The emergence of the multi-collector ICP-MS emerging paradygm; these chemical sediments were common under for high-precision in situ measurement of radiogenic (e.g. Hf in Fe-rich conditions in the Archean and Paleoproterozoic oceans. zircon [1]) and ‘non-traditional’ stable isotopes (e.g. Cu and Fe in Here, we report detailed sedimentological, stratigraphic, sulfides) has revolutionised analytical geochemistry. On the laser petrographic and geochemical data from an Ediacaran IF and front, Nd:YAG (266, 213 or 193 nm) or ArF excimer (193 nm) associated rocks, including ‘iron-rich’ black shales, siltstones and remain the most commonly used laser sources. In comparison with cherts of the Arroyo del Soldado Group in Uruguay [1]. The IF and these nanosecond pulse-width systems, ablation using femtosecond cherts occur at the top of two siliciclastic units characterized by lasers has been shown to approach stoichiometric sampling and retrogradational stacking patterns with fining-upward cycles reduce laser-induced fractionation effects. However the high cost of deposited during transgressive system tracts and represent two the commercial femtosecond systems has restricted their uptake. major episodes of basin flooding and sediment starvation. Despite the significant advances of the last decade, the Geochemically, the IF and cherts have coherent rare earth element continued rapid spread and acceptance of the technology may be and yttrium (REY) patterns and display the essential shale- jeopardized while any significant analytical issues remain unsolved. normalized characteristics of marine precipitates. REY signatures The accuracy and precision of in situ isotope ratio measurements and mixing calculations show that they differ from Archean and are inherently lower than solution measurements because of the Paleoproterozoic IF as far as high-temperature hydrothermal input complexity of matrix effects and corrections for mass bias and did not influence their chemistry. Instead, we suggest that low- isobaric interferences. Optimising precision of elemental and temperature hydrothermal input may account for the geochemical isotope ratio measurements while maintaining spatial resolution signatures displayed. By analyzing the REY signature of chemical brings challenges, and emphasises the need for improved precipitates (cherts and IF) and evaluating the redox chemistry of the understanding of measurement uncertainties and error budgets. Well marine water column within a sedimentological and sequence characterized and readily available reference materials combined stratigraphic framework, our results confirm that ferruginous with more inter-laboratory comparison exercises are essential. conditions dominated the pre-Gaskiers but also the post-glaciation Future goals for LA-ICP-MS include a quantum increase in deep-water chemistry. Therefore, global ocean oxygenation may not sensitivity, fine-scale compositional mapping of geological samples, have occurred unitl well into the upper Ediacaran or even during the and overcoming effects of elemental and isotopic fractionation. Cambrian as was recently proposed [2]. Elimination of elemental fractionation will accelerate development of procedures to measure major, minor and trace-element [1] Pecoits et al. (2011) Precambrian Research in press. [2] abundances without depending on matrix-matched calibration Canfield et al. (2008) Science 321, 92-95. materials and independently determined internal standard concentrations.

[1] Griffin et al. (2000) Geoch. Cosm Acta 64, 133-147.

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Revisited multicomponent chemical Evolutionary Response of S Isotope geothermometry: application to the Fractionation by Sulfate Reducing Dixie Valley geothermal area Microorganisms

EIFFER ANNER PYCHER ONNENTHAL B M L. P *, C. W , N. S , E. S , . . 1 2

KENNEDY ANDRÉ PELLERIN *, NADIA MYKYTCZUK , REBECCA 1 3 2 3 AUSTIN , GRANT M. ZANE , LYLE WHYTE , JUDY D. WALL , 1 Lawrence Berkeley National Laboratory, Berkeley, USA, AND BOSWELL WING [email protected] (* presenting author) 1Department of Earth and Planetary Sciences, McGill University, The multicomponent chemical geothermometry method [1,2] Montréal, Canada, [email protected] (* presenting involves computing the saturation indices of potential reservoir minerals over a range of temperatures, given a known geothermal author), [email protected], fluid composition, then inferring reservoir temperature from the [email protected] clustering of mineral saturation indices near zero. This method was 2Department of Natural Resource Science, McGill University, St- automated as a stand-alone computer program (geoT), easing its Anne de Bellevue, Canada, [email protected], application and allowing optimization of model input parameters [email protected] using parameter-estimation software [3]. The code can process 3University of Missouri, Biochemistry Division, Columbia, USA, simultaneously multiple water compositions, and correct for [email protected], [email protected] dilution and mixing effects as well as gas loss. The temperature of the reservoir is estimated from statistical analysis of computed mineral saturation indices. One difficulty of the method is that it is sensitive to potentially erroneous Al chemical analyses, an issue Microbial sulfur isotope fractionation is controlled by the which can be partly resolved by resorting to computed Al energy metabolism of sulfate reducing microorganisms. It concentrations assuming equilibration with selected Al-bearing represents a well-defined and precisely measurable characteristic of minerals [2]. the phenotype of the microorganism. As such, it is dependent both The geothermometry method and new code are being tested on on the underlying genotype and on the response of that genotype to geothermal fluids from Dixie Valley (Nevada, USA) using an variability in the local environment. Since genotype and environment extensive set of water and gas analyses [4]. These data include total have both changed throughout Earth’s history, the geological record and dissolved (“ionized”) Al analyses in filtered (0.45 and 0.2 Pm) of biogenic S isotopes must reflect the influence of both and unfiltered water samples, allowing testing the effect of these environmental change and molecular evolution. However, the basic various reported Al concentrations on predicted temperatures. A set interplay between microbial evolution and S isotope fractionation of minerals prevailing in the geothermal reservoir was assumed has not been examined. based on XRD data from well cuttings [5]. Gas analyses were added back to the well waters, and increased salinity effects caused by the We investigated the evolutionary response of S isotope reinjection of flashed brines into the reservoir were also considered. fractionation in the sulfate-reducing bacterium Desulfovibrio Using “ionized” Al concentrations in unfiltered samples, reservoir vulgaris Hildenborough (DvH). Two bacteria – the wild type DvH temperatures of ~250°C were obtained. These temperatures were as well as a mutant derived from that strain in which one copy of a similar to values obtained by computing Al concentrations assuming gene putatively encoding lactate dehydrogenase was deleted and equilibrium with Al minerals (albite, microcline, muscovite). These replaced with an antibiotic resistance cassette were used as model o temperatures seem reliable because they are consistent with organisms. In defined media (sulfate and lactate limited) at 33 C, measured downhole water temperatures. In contrast, the 0.2-μ ancestral wild type and mutant DvH exhibit fractionation factors that filtered Al analyses led to lower computed temperatures close to reproducibly differ by 0.5‰. We serially transferred six replicate sampling temperatures (160°–180°C) and corresponding to lines of the wild type and six replicate lines of the mutant for 600 different equilibrated minerals. In this case, the 0.2-μ filtered Al generations in batch cultures. Over the course of the experiments, concentrations appear too low, apparently reflecting the filtering-out we assayed fitness through direct competition experiments between of colloidal Al formed by cooling. Hot spring waters from the wider the ancestral mutant and descendant wild-type strains (or vice versa). Dixie Valley area were also investigated. The lack of consistency In these competition experiments, we used qPCR to monitor the between their reconstructed equilibrium temperatures, as well as relative abundance of the mutant through a unique genetic barcode significant differences in their chemical composition may indicate associated with the antibiotic resistant cassette. After 300 that Dixie Valley hosts several distinct reservoirs. Batch generations, the descendant strains were markedly more fit than geochemical modelling and reactive transport simulations are being their ancestors, with relative growth rate increases of nearly 30%. conducted to understand processes affecting the deep geothermal This means that the descendant strains have a clear selective fluids on their way to the surface and to characterize the hydrologic advantage in the defined media, illustrating that DvH can undergo relations between the deep reservoir and the superficial hot springs. evolutionary adaptation on laboratory timescales.

Despite the clear evidence for evolutionary changes over the References course of our experiment, isotopic assays of the descendant wild- [1] Reed, M.H., Spycher, N.F. (1984), Geochim. Cosmochim. Acta type and mutant strains reveal that the 0.5‰ difference in their 48 1479-1492. [2] Pang, Z.H., Reed, M.H. (1998), Geochim. fractionation factors is conserved. Preservation of such a small Cosmochim. Acta 62 1083-1091. [3] Spycher, N. et al. (2011), isotope effect implies that the sulfate reducing energy metabolism Geoth. Resource Council Transactions 35 663-666. [4] Goff, F. et is remarkably robust to the selective pressures of our experimental al. (2002), Los Alamos National Laboratory Report LA-13972-MS, setup. Los Alamos, NM 71pp. [5] Lutz, S.J. et al. (1998), Proceedings, Twenty-Third Workshop on Geothermal Reservoir Engineering, Stanford University 315-321.

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Discovery of metals-rich Organic geochemisty of the Late hydrothermal manganese deposits in Paleozoic black mudstone in Hailaer the South-West Pacific 1 1 1 1 basin, NE China: Implications for E. PELLETER *, Y. FOUQUET , J. ETOUBLEAU , S. CHERON , 1 S. LABANIEH AND THE SCIENTIFIC PARTIES hydrocarbon-forming potential 1 Ifremer c/Brest, Laboratoire de Géochimie et Métallogénie, BP70, X.L. PENG*, N. LIU, L. LIU 29280, Plouzané, France College of Earth Sciences, Jilin University, Changchun, (*correspondance: [email protected]) 130061,China (*correspondence: [email protected])

Manganese oxides in the deep marine environment can be It is being dissussed hotly that whether the Late Paleozoic strata separated in three genetic groups: (i) hydrothermal, (ii) in NE China have hydrocarbon forming potential or not. However, hydrogenetic, and (iii) diagenetic. The hydrothermal Mn deposits are organic geochemical data of the black mudstones from the Late characterized by low to very low contents of Cu, Ni, Co, Zn whereas Paleozoic in Hailaer basin provides insights for that. It has been the hydrogenetic Mn deposits can be enriched in a characteristic known that the Mesozoic strata in Hailaer Basin NE China, was a suite of trace elements (e.g. Co, Ni, Zn, REE, HFSE, Pt). As a famous hydrocarbon accumulation zone. In addition, the outcrop consequence, only hydrogenetic manganese crusts and polymetallic rocks of the Carboniferous and Permian around the basin was in the nodules have been considered as a potential resource for some late stage of diagenetic and low-lever metamorphic belt [1]. commercially important metals. Here we report on occurrence of Amount to 39 wells of Beier and Wuerxun depression from metals-rich hydrothermal manganese deposits discovered in the Hailaer basin were drilled into the Paleozoic black mudstone, and south-west Pacific during a French cruise (fall 2010). These the thickness of the mudstone is about 393m. In this research, deposits occur at depth between 800m and 1800m and are organic geochemical analysis has been taken on 40 black mudstone controlled by volcanic structures. Volcanism is dominated by samples from 11 selected wells. It is indicated that the TOC values pyroclastic rocks (e.g. hyaloclastite, tuffite, pumice) at depth ranged between 0.09% and 4.407%, with the mean value of 0.73%, shallower than 1000 m and by pillow-lavas at greater depth. and 40% samples are over threshold of the organic matter abundance Mineralization occurs as crusts, meter-scale mounds and (0.5). impregnations composed of well-crystallized birnessite and Organic geochemical analytical data for the Late Paleozoic todorokite with variable amount of iron oxy-hydroxide and black mudstones in the well of Wu 9 and Bei 2 of Hailaer basin was nontronite. The manganese oxides exhibit bluish-black to grey-black collected from Daqing oil field. TOC values from Wu 9 (7 samples) color with a submetallic luster typical of many hydrothermal Mn show a mean value of 0.9%, and the maximum value is 1.66%, thus mineralizations [1]. Mn oxides are abnormally enriched in Ni (up to about 43% samples are moderate source rocks. The potential of 4.6%), Co (up to 2.2%) and Cu (1.5%) but exhibit low REE and pyrolysis hydrocarbon generation values are 4.4mg/g ~ 0.01mg/g HFSE concentrations. Post-Archean Australian Shale-normalized (average 1.5mg/g), suggesting that 33.3% samples can be regarded REE patterns exhibit typical seawater signature with prominent as moderate source rocks. For the black mudstones from Bei 2 (29 negative Ce anomalies. Therefore, trace elements data point to a samples), the average values for TOC and S1+S2 are 0.733% and contribution of hydrothermal fluids for Ni, Co and Cu and a seawater 0.35 mg/g. The average value for IH is 26mg/g (maximum contribution for REE and HFSE. Further, different genetic models to 123mg/g), showing a typical kerogen type of III. The mean values for explain the mechanism for metal enrichment will be discussed. Tmax and Ro are 433°C and 0.81, respectivety, suggested that the

source rock are high maturity. Combined with the Paleozoic strata in

Hailaer Basin is well-protected, we consider that this strata could

[1] Eckhardt et al. (1997) Mar. Georesour. Geotechnol. 15, 175- have a good hydrocarbon-forming potential, and the source rocks 208. from the Late Palezoic strata in Hailaer basin could be an ideal target for a new round of hydrocarbon exploration in NE China.

[1] Hu and Yu. (2009) Acta Petrologica Sinica. 25(8), 2017-2022

This research was financially supported by the Natural Science Foundation of China (40972075) and the Strategic Research Center of Oil & Gas Resources (14B09XQ1201).

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Geogas Nano Material Elements The study on the solubility of the Analysis For Detecting Concealed vanadium system focused on Structures in Dashui Gold Deposit in Panzhihua, China Gansu Province, China Y. PENG1,2, Y. ZENG*1,2 1,2 3* 1 XIUHONG PENG , HUI DENG , BO XU ,CHENGSHI 1College of Materials and Chemistry & Chemical Engineering, 1 1,4 QING ,JIANGSU ZHANG Chengdu University of Technology, Chengdu, Sichuan, 610059,

1 P. R. China Geochemistry Dep., Chengdu University of Technology , China 2 2 Mineral Resources Chemistry Key Laboratory of Sichuan Higher Key Laboratory of Nuclear Techniques in Geosciences, China 3 Education Institutions, 610059, P. R. China State Key Laboratory of Geohazard Prevention and (* correspondence: [email protected]) Geoenvironment Protection, Chengdu University of Technology (*correspondence:[email protected]) In recent years, the interest of the relationship between 4 Third Geology and Mineral Resources Exploration Academy of microelement and human health increased. Vanadium absence may Gansu Province, Lanzhou, China have negative effects, and it also can be toxic if exposure occurs at The nanoparticles in ore bodies can adsorb on gas and migrate in high enough levels. It has strong transfer ability in environment. This the updraft. It has strong penetrability which can rise vertically from ability related to the solubility of vanadium in soil solution. the deep Earth to the surface, and creates a distribution anomaly Panzhihua, Sichuan is an important production base of vanadium (geogas anomaly) of nano material above the projection of ore and titanium magnetite. The vanadium storage is 64% of the total bodies. Many scholars[1]-[2] have confirmed the prospecting effect vanadium in China. The vanadium mining and smelting accelerated of geogas method. From 1988 to 1999, Chunhan Tong et al. [3]-[4] the vanadium diffusion in soil and water. It causes special had experimented on the geogas measure method in Laojie Gold environmental problems of vanadium in Panzhihua. Different surface Deposit in Yunnan Province and so on successively. They had soil in the region, the average mass fraction of vanadium is over 100 successfully indicated the locations of ore bodies hundreds of × 10-6,[1] far exceeding the background values of Chinese soil meters deep underground, and observed the nanoparticles in geogas. vanadium 86 × 10-6.[2] The amount of vanadium in the soil The dynamic geogas analysis adopted in this research is to use surrounding smelter is 16.5 times of contrast values. The amount of the pump to exact the geogas in the cover; then the nano materials vanadium in the plant samples is 6.6 times of contrast values.[3] will be captured by the liquid capture agent; and finally the various The solubility of vanadium in soil solution is effected by kinds of elements in geogas can be analyzed by ICP-MS to obtain the coexisting ions in soilˈsuch as potassium, sodium, phosphorus and geogas information. Combining the geochemical exploration and the so on. In order to investigate the relationship of solubility between actual situation of the mine, five exploration lines and 40 elements vanadium and the other co-existing ion in soil, the phase equilibria

of 139 samples were set in the survey area, including two of the quinary system NaVO3 + KVO3 + NaH2PO4 + KH2PO4 +

experiment measuring lines on the known ore bodies. (NH2)2CO + H2O and its five quaternary sub-systems were studied at Results and Conclusion 298 K with isothermal dissoluble method. According to the On the basis of the analysis of the trace elements and rare earth experimental results, the crystallization form of metavanadate is elements characteristics in ores and wall rocks, and the comparison polyoxovanadate in the weakly acid system. The dissolution and of the geogas experimental profile, the geogas indicating elements migration of vanadium in aqueous solution has negative correlation - ˇ were selected. The geogas indicating elements characteristics of the with H2PO4 and (NH2)2CO. The exisiting of K has little effect on three exploration lines demonstrate that there are two concealed the solubility of vanadium. This suggest that in similar soil faults: one concealed structure and one ore-controlling structure in environment, the solubility of vanadium was restrained by the - the survey area. The first concealed structure goes through No.7-13 increase of H2PO4 and (NH2)2CO, which can affect the transfer measure point of Line a, No.15-19 measure point of Line b and ability of vanadium. No.7-14 measure point of Line c. The width of the structure (or the The authors acknowledge the support of the National Natural combination width of multiple microcracks) is 90-200m. The Science Foundation of China(40673050, 41173071), and the second ore-controlling structure goes through No.25 measure point Research Fund for the Doctoral Program of Higher Education from of Line a, No.23-27 measure point of Line b and No.23-28 measure the Ministry of Education of China (20115122110001). point of Line c. The width of the structure is about 80-100m. Because the results of radon survey is as the same as the geogas’s, [1] Teng, Tuo, Ni. (2003) Chinese Journal of Geochemistry, 22, the prospecting exploration efforts should be greatly strengthened in 253-262. [2] Wei, Chen, Zheng. (1991) Environmental Science, 12, the western periphery of Dashui Gold Deposit. 12-19. [3] Wang, Wei. (1995) Element Chemistry of Soil The authors acknowledge the support of the National Environment, 231-241. Nature Science Foundation of China (No.41103025) and Cultivating Programme of Middle-aged Backbone Teachers of Chengdu University of Technology [1] Kristanssonk et al. (1990) Endeavour (New Series) 14, 28- 33.[2] Wang et al. (2005) GEOLOGY IN CHINA 32, 135-140.[3] Tong et al. (1997) J MINERAL PETROL 17, 83-88.[4] Tong et al. (1999) CHINESE JOURNAL OF GEOPHYSICS 42, 135-142.

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Do Critical Zone carbon and water Modeling the hydrothermal fluxes control chemical denudation? circulation and the hydrogen production at the Rainbow site with 1* 2 1 Cast3M JULIA N. PERDRIAL , PAUL BROOKS , JON CHOROVER , KATE 2 2 1 1* 1 CONDON , ADRIAN HARPOLD , MOLLY HOLLERAN , DAVID FLORIAN PEREZ , CLAUDE MÜGLER , PHLIPPE JEAN- 2 1 2 1 2 HUCKLE , REBECCA LYBRAND , PETER TROCH , JEN BAPTISTE AND JEAN LUC CHARLOU . 2 2 3 MCINTOSH , TOM MEIXNER , REBECCA MINOR , BHASKAR 1 3 1 1 LSCE, CEA-CNRS-UVSQ, Gif-Sur-Yvette, France MITRA , MICHAEL POHLMANN , CRAIG RASMUSSEN , TYSON 3 1 [email protected] (* presenting author) SWETNAM , ANGELICA VASQUEZ-ORTEGA , XAVIER ZAPATA- 2 2 Géosciences Marines, IFREMER, Brest, France RIOS [email protected] 1University of Arizona, Department of Soil, Water and Environmental Sciences, Tucson, AZ, USA, Background and Aims [email protected] (*) On the Mid-Atlantic Ridge, the Rainbow venting site is described as 2University of Arizona, Department of Hydrology and Water an ultramafic-hosted active hydrothermal site and releases high Resources, Tucson, AZ, USA fluxes of methane and hydrogen [1, 2]. This behavior has first been 3University of Arizona, School of Natural Resources, Tucson, AZ, interpreted as the result of serpentinization processes. But USA geochemical reactions involving olivine and plagioclase assemblages, and leading to chlorite, tremolite, talc and magnetite What controls the magnitude of weathering fluxes in the assemblages, could contribute to the observed characteristics of the Critical Zone (CZ) and how vulnerable are those fluxes towards exiting fluid [2]. changes in climatic forcing? We believe that these fundamental Objectives and methods questions can be uniquely addressed through an integrative approach The predominance of one of these geochemical reactions or their that includes multiyear CZ water, carbon and lithogenic element flux coexistence strongly depend on the hydrothermal fluid circulation. records using a scaling approach that bridges multiple CZ sub We developed and validated a 2D/3D numerical model using a Finite disciplines. Based on the theoretical framework of the Santa Volume method to simulate heat driven fluid flows in the framework Catalina Mountains - Jemez River Basin (SCM-JRB) CZO, we of the Cast3M code [3, 4]. We also developed a numerical model for postulate that effective energy and mass transfer (EEMT, MJ m-2 y- hydrogen production and transport that is based on experimental 1,[1]) is a predictive variable for chemical denudation. This studies of the serpentinization processes [5]. This geochemical parameter can be estimated from meteorological variables, as we model takes into account the exothermic and water-consuming have done previously for our CZO [2], or it can be measured behavior of the serpentinization reaction and it can be coupled to our directly, as we report in this presentation. Within the CZO thermo-hydrogeological model. framework, we are now testing the hypothesis that direct hydrologic Results and conclusion and organic geochemical quantifications of EEMT in CZ fluids are Our simulations provide temperatures, mass fluxes and venting correlated with fluxes of major and trace lithogenic elements for surface areas very close to those estimated in-situ [6]. We showed several montane forest catchments. Rare earth elements (REE) are that a single-path model [7] was necessary to simulate high values investigated as tracers for chemical denudation mechanisms and such as the in-situ measured temperatures and estimated water mass preliminary data on REE-organic carbon interaction indicate the fluxes of the Rainbow site [6]. importance of labile organic carbon (the biomass energy flux component of EEMT) as a key controller of chemical denudation patterns. Climatic impacts on inter-annual variations in EEMT seem to exert an overarching constraint on chemical denudation. [1] Rasmussen et al. (2010). An open system framework for integrating critical zone structure and function. Biogeochemistry. 102, 15-29. Figure 1: Temperature field [2] Chorover et al. (2011). Probing how water, carbon, and obtained with a single-path model. energy drive landscape evolution and surface water dynamics: The Jemez River Basin – Santa Catalina Mountains Critical Zone This single-path model will be used to model the production and Observatory. Vadose Zone Journal. 10, 884-899. transport of hydrogen at the Rainbow hydrothermal site.

[1]Charlou et al. (2010) AGU Monograph series. [2]Seyfried et al. (2011) Geochim. Cosmochim. Acta 75, 1574-1593. [3]http://www- cast3m.cea.fr. [4]Martin & Fyfe (1970) Chem. Geol. 6, 185-202. [5] Marcaillou et al. (2011) Earth and Planet. Sci. Lett. 303, 281-290. [6]Perez et al. (2012) submited to Computational Geosciences. [7]Lowell & Germanovich (2004) AGU, Washington DC, USA.

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El Niño impact on mollusk shell Mobility of trace elements from the biomineralization Sunbury Shale, eastern Kentucky

1* 1,2 1* 2 3 ALBERTO PÉREZ-HUERTA , MIGUEL F. ETAYO-CADAVID , ROBERT PERKINS , CHARLES MASON , AND DAVID PIPER 1 3 C. FRED T. ANDRUS , AND TERESA E. JEFFRIES 1Portland State University, Department of Geology, Portland, OR,

1 Department of Geological Sciences, The University of Alabama, USA, [email protected] (*presenting author) Tuscaloosa, AL 35487, USA, [email protected] (* presenting 2Morehead State Univeristy, Earth and Space Sciences, author) 2 Morehead, KY, 40351, USA BP America Inc., Houston, TX 77079, USA, [email protected] 3 U.S. Geological Survey, Mineral Resources Group, 3 Mineralogy Department, Natural History Museum, London SW7 Menlo Park, CA, USA 5BD, UK, [email protected]

Marine macroinvertebrates are ideal sentinel organisms to Black shales contain high concentrations of trace elements and monitor rapid environmental changes associated with climate may serve as important sources of strategic metals, U and REEs as change. Chemical proxies from mollusk shells are widely used for conventional ore deposits become scarcer. However, the increased detecting variations in seawater parameters (e.g., temperature and use of hydrofracturing for shale gas development as well as possible productivity) related to such changes. However, the influence of future mining and processing of black shales for extraction of shale known, and recurrent, climatic events on biological processes during oil could potentially facilitate release of toxic trace elements to active mineralization, and thus on shell chemistry, is still hydraulic fracturing or retort process waters, surface water and insufficiently understood. Analysis of Peruvian cockles from the 1982-83 large magnitude ground water. Quantifying the concentrations and relative mobility El Niño event show significant alterations in shell biomineralization, of trace elements from black shales is thus important from both linked to microstructural changes and the loss of organic matrix economic and environmental perspectives. A better understanding of components. These alterations are associated to modifications in trace element mobility from natural weathering of these deposits magnesium and barium content of aragonite cross lamellar shell may also be of use for researchers using outrcop samples to layers, while strontium content is nearly constant throughout the determine paleodepositional conditions. event. An increase in magnesium is a possible response of the The Sunbury Shale (lower Mississippian) is one of the youngest mollusk specimens to the loss of proteins and the need for the stabilization of amorphous calcium carbonate. Additionally, the units making up the thick Devonian and Mississippian black shale increase of barium after the El Niño onset is related to upwelling. sequence in the Appalachian Basin. This study compares the trace Overall, these findings contribute to a better understanding the element geochemistry of samples collected from two exposures of effects of abrupt climate change on mollusk shell structures, while Sunbury Shale located < 8 km apart along the eastern margin of the also offering a new view for proxy application to the reconstruction Cincinnati Arch (western flank of the Appalachian Basin). At one of El Niño events. site, fresh to minimally weathered samples were collected from a

roadcut excavated only a month prior; the second site was a roadcut

exposed for ~40 years, wherein the shale was visibly weathered. The

Sunbury Shale has, on average, higher levels of trace elements than

the much thicker Devonian Ohio Shale that outcrops in the study

area (Perkins et al., 2008) and its 5-m thickness readily allowed for

comparative sampling of the entire unit from each of the sites. The results indicate that the 40 year period of surface weathering resulted in significant (D= 0.05) loss of some trace elements, particularly those associated with sulfides (e.g., Cd, Cu, Ni, Zn). No significant differences were found with respect to the concentrations of Cr, Mo, V that are associated with refractory phases. No significant differences were found with regards to As or Se concentrations, although these elements are also associated with sulfides. This may be due to preferential sorption of these oxyanions under the locally acidic conditions resulting from sulfide oxidation.

[1] Perkins, Piper, and Mason (2008), Palaeogeography, Palaeoclimatology, Palaeoecology 265, 14-29.

Mineralogical Magazine | www.minersoc.org 2220 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Atmospheric iron from crustal Hg stables isotopes assessing sources: prognostic aerosol methylmercury bioaccumulation, sources, composition in GISS/ModelE and metabolization in the pelagic food web of Lake Baikal (Russia) 1 1* 1 JAN P. PERLWITZ , CARLOS PÉREZ , RON L. MILLER 1 2 1 2 VINCENT PERROT *, MIKHAIL PASTUKHOV , VLADIMIR N. EPOV , AND SERGIO RODRIGUEZ 1 1 DAVID AMOUROUX AND OLIVIER F.X. DONARD 1NASA Goddard Institute For Space Studies and Dept of Applied 1 Physics and Applied Math, Columbia University, New York, Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, IPREM, CNRS-UPPA-UMR-5254, Pau, France (*[email protected] USA, [email protected], [email protected], pau.fr) [email protected] (* presenting author) 2 Laboratory of geochemical mapping and monitoring, Institute of 2 Izaña Atmospheric Research Centre, Agencia Estatal de Geochemistry SB RAS, 1A Favorskogo Street, PB-304, Irkutsk, 664033, Meteorología, Tenerife, Spain, [email protected] Russia

Monomethylmercury (MMHg) is the main chemical form of Introduction mercury that threatens human populations via food consumption after its The emission of aerosol iron from crustal sources is subject to bioaccumulation and biomagnification in food webs [1]. Nowadays, Hg significant uncertainty. Many atmospheric model studies assume stable isotopes mass dependent and mass independent fractionation spatially homogeneous total iron content at dust sources, typically (MDF and MIF) is a powerful tool to identify Hg sources and 3.5% by mass. Moreover, as iron oxides and hydroxides are transformations within the environment [2]. In aquatic ecosystems, comprised of more than 50% iron by mass, models usually consider several Hg transformations may affect Hg molecular speciation and thus Hg isotopes fractionation, inferring toughness to unravel accurately Hg them as the main suppliers of dissolved iron resulting from dust isotopic signature observed in samples. The aim of this study was to deposition. A recent experiment [1] has shown a large contribution investigate Hg bioaccumulation, trophic transfer and its metabolization in by clays - their low iron content offset by their large solubility - to top predator organs, through the measurement of total Hg isotopic the total dissolved iron from dust samples. This and other studies composition and Hg compounds (i.e. MMHg and inorganic Hg(II)) suggest the need for explicit representation of individual minerals in specific isotopic composition (CSIC) in the pelagic food web of the dust-climate models in order to improve our understanding of the oligotrophic and remote freshwater Lake Baikal (Russia). Carnivorous pelagic sculpins fish (Comephoridae and atmospheric iron cycle and iron deposition as an input to ocean Cottocomephoridae families) and their predator seals (Phoca sibirica) biological productivity. were especially investigated. Significant MIF was observed in both Methodology samples with no significant differences (∆199Hg of 4.59±0.55‰ (n=27) We have implemented prognostic budgets of separate mineral and 4.62±0.60‰ (n=7), respectively. This high MIF was related to types into an Earth System Model: GISS/ModelE. Each mineral type efficient MMHg demethylation before bioaccumulation in organism’s (composed of iron and/or other elements) is separately transported muscles. On the other hand, Hg trophic transfer (from sculpins to seals) and modified within the atmosphere. Spatially-dependent does not produce Hg MIF whereas MDF is likely during this process since seals muscles have δ202Hg about 1‰ higher than sculpins muscles. concentrations of illite, kaolinite, smectite, calcite, quartz, feldspar, Seals organs (liver, kidney, muscle, hair, intestine …) displayed iron (hydr)oxide, and gypsum are predicted by the model based on an significantly different Hg speciation, with liver and kidney mostly updating of the source mineralogy proposed in the seminal work of composed of Hg(II) whereas hair and muscle have more than 80% [2]. We use downwind observations to constrain the mineral content MMHg (figure 1). of aerosols leaving the source. Discussion

We evaluate model results against global observations of mineral aerosols with emphasis on multiyear measurements of size- segregated dust elemental composition at the Izaña Observatory (Tenerife, Canary Islands), situated downwind of important North African dust sources. We highlight the strengths and limitations of

the source prescription of [2] and propose new strategies to represent mineral tracers in dust models.

202 [1] Journet at al. (2008) Geophys. Res. Let 35, L07805. [2] Claquin Figure 1. δ Hgtot as a function of the fraction of inorganic Hg in seals et al. (1999) J. Geophys. Res 104, D18, 22,243-22,256. tissues

Hg CSIC in seals tissues showed MMHg and Hg(II) enriched in heavier and lighter isotopes, respectively, with a δ202Hg difference of about 3.2‰. MMHg demethylation in these top predator mammals was thus identified as a major process leading to MDF, but no MIF, of Hg isotopes before storage and/or elimination within the different organs, such as residual MMHg in muscle and Hg(II) in liver. [1] Morel et al. (1998). Annual Review of Ecology and Systematics, Vol ume 29, pp543-566 [2] Bergquist and Blum (2009). Elements, Vol ume 5, pp353-357

Mineralogical Magazine | www.minersoc.org 2221 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts New insights on crystal growth and Metasomatic control of water in dissolution by investigating micro- garnet and pyroxene from Kaapvaal scale entities. craton mantle xenoliths *1 1 1,2* 3 4 MASSIMO PERUFFO , MICHAEL M. MBOGORO AND PATRICK ANNE H. PESLIER , ALAN B. WOODLAND , DAVID R. BELL , 1 5 6 R. UNWIN MARINA LAZAROV AND THOMAS J. LAPEN 1Electrochemistry and Interfaces Group, Department of Chemistry, 1Jacobs Technology - ESCG, Houston TX, USA, The University of Warwick, Coventry, CV4 7AL, UK. [email protected] (* presenting author) 2NASA - JSC, Houston TX, USA [email protected] (* presenting author) 3Universität Frankfurt, Germany, [email protected] 4Arizona State University, Tempe AR, USA, [email protected] Abstract 5Universität Hannover, Germany, [email protected] A new approach to the study of crystal growth/dissolution hannover.de kinetics is reported, that involves measuring the time-evolution of 6University of Houston, TX, USA, [email protected] entire isolated micro-crystals or micro-etch pits in macro crystals 1,2 via a variety of microscopic techniques (2D and 3D). By coupling Fourier transform infrared spectrometry (FTIR) and laser such measurements to finite element diffusion models, the ablation inductively coupled plasma mass spectrometry (LA- importance of mass transport to the overall rates can be elucidated ICPMS) were used to determine water, rare earth (REE), lithophile readily. Furthermore the approach reveals directly plane-specific (LILE), and high field strength (HFSE) element contents in garnet intrinsic kinetics free from diffusional effects. Investigations on and pyroxene from mantle xenoliths, Kaapvaal craton, southern gypsum (CaSO4.2H2O) highlight notable sensitivity to solution Africa. Water enters these nominally anhydrous minerals as protons 2+ 2- stoichiometry (Ca and SO4 ratio) which results in different bonded to structural oxygen in lattice defects [1,2]. Pyroxene water 3 crystal and pit morphology . In summary, the method is powerful in contents (150-400 ppm in clinopyroxene; 40-250 ppm in linking microscopic observations to macroscopic rates and is orthopyroxene) correlate with their Al, Fe, Ca and Na and are expected to be of general applicability. homogeneous within a mineral grains and a xenolith. Garnets from Jagersfontein are chemically zoned for Cr, Ca, Ti and water

contents. Garnets contain 0 to 20 ppm H2O. Despite the fast diffusion rate of H in mantle minerals [3], the observations above indicate that the water contents of mantle [1] Fan, C.; Teng, H. H. (2007) Chem. Geol. 245, 242-253. xenolith minerals were not disturbed during kimberlite entrainment [2] Luttge, A.; Arvidson, R. S. (2010) J. Am. Ceram. Soc. 93, 3519- and that the measured water data represent mantle values. Trace elements in all minerals show various degrees of light REE and LILE 530. enrichments indicative of minimal to strong metasomatism. Water [3] Zhang, J.; Nancollas, G. H. (1992) J. Cryst. Growth 118, 287- contents of peridotite minerals from the Kaapvaal lithosphere are 294. not related to the degree of depletion of the peridotites. Instead, metasomatism exerts a clear control on the amount of water of mantle minerals. Xenoliths from each location record specific types of metasomatism with different outcomes for the water contents of mantle minerals. At pressures ≤ 5.5 GPa, highly alkaline melts metasomatized Liqhobong and Kimberley peridotites, and increased the water contents of their olivine, pyroxenes and garnet. At higher pressures, the circulation of ultramafic melts reacting with peridotite resulted in co-variation of Ca, Ti and water at the edge of garnets at Jagersfontein, overall decreasing their water content, and lowered the water content of olivines at Finsch Mine. The calculated water content of these melts varies depending on whether the water

content of the peridotite (2 wt% H2O) or individual minerals (<0.5-

13 wt% H2O) are used, and also depend on the mineral-melt water partition coefficients. These metasomatic events are thought to have occurred during the Archean and Proterozoic, meaning that the water contents measured here have been preserved since that time and can be used to investigate viscocity and longevity of cratonic mantle roots [4].

[1] Bell & Rossman (1992) Science 255, 1391-1397. [2] Peslier (2010) JVGR 197, 239-258. [3] Ingrin & Blanchard (2006) MSA- RMG 62, 291-320. [4] Peslier et al. (2010) Nature 467, 78-81.

Mineralogical Magazine | www.minersoc.org 2222 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Experimental vapor-liquid Nucleation: concentration partitioning of transition metals in fluctuations and polymorph selection

1 NaCl dominated fluids BARON PETERS 1* 1 NICHOLAS J. PESTER , KANG DING , AND WILLIAM E. 1University of California at Santa Barbara, Chemical Engineering, 1 SEYFRIED, JR. [email protected] 1Dept. of Earth Sciences, University of Minnesota, Minneapolis, MN, U.S.A. (* presenting author: [email protected]) Nucleation is the stochastic process that creates the first stable

embryo of a new phase to initiate a phase transition. The mechanism Multi-phase fluid flow is a common occurrence in magmatic is poorly understood because rare events processes like nucleation hydrothermal systems, and extensive modeling efforts using present special challenges to both experiments and simulations. The empirically derived PVTx properties of the NaCl-H2O system are difficulties are particularly acute for multi-component condensed frequently conducted. We have performed hydrothermal flow phase nucleation processes where most applications lie. I outline experiments in the near-critical and two-phase region (410-465 °C, recent advances toward understanding nucleation mechanisms. First, I 250-400 bars) to derive sufficiently resolute partition coefficients for show how the free energy landscape and dynamics for development some important accessory metals. NaCl solutions (3-6 wt%) of competing polymorphs can be understood using simulations.[1,2] containing variable amounts (1-20 mmolal) of alkaline earth and Then I present a new droplet theory of nucleation that couples local transition metal chlorides were pumped through a Ti alloy reactor concentration fluctuations to nucleus size evolution.[3] The new with an outlet control valve capable of maintaining set pressure theory may explain why recent simulations with very different solutes within ± 0.5 bars. Flow rates were optimized to obtain the equilibrium show similar two-step nucleation mechanisms. vapor phase and the coexisting liquid was then simultaneously sampled. The included figure shows Zn data as a representative [1] Peters (2009) J. Chem. Phys. 131, 224103. [2] Duff, Peters (2011) example of the metals studied (shown normalized to starting J. Chem. Phys. 135, 134101. [3] Peters (2011) J. Chem. Phys. 135, composition of the single phase fluid). Na dominates phase behavior 044107 (2011). in the system, where all metal cations must be charge balanced

2 Na Zn

s 0 uid near/within halite liq ) stability field start -2

/M

vap or liq -4 rs po ln (M va -6

single-phase fluid (start)

-8 -4 -2 0 2 ln (Cl /Cl ) vap or liq start by Cl. The Zn/Na ratio decreases with chlorinity in the vapor phase until conditions approach halite saturation where the trend abruptly reverses with a concommitant decrease in pH (possibly due to hydrolysis). Such volatility may play an important role in concentrating transition metals in magmatic hydrothermal systems. Uniform slopes for each metal in the vapor phase equate to relative partition coefficients (Na = 1) of the order: Cu(I) ” Na < Fe(II) < Zn < Mg ” Ni(II) ” Mn(II) ” Co(II) < Ca < Sr < Ba. While the absolute concentration of such elements in natural fluids is controlled to a first order by temperature dependant mineral solubility, phase separation can be decoupled from fluid-mineral equilibria depending on flow rate/residence time. Thus, such partition coefficients can be used to aid in both geochemical modeling and reconstruction of P-T history for multiple hydrothermal fluid samples or inclusions.

Mineralogical Magazine | www.minersoc.org 2223 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Combining spectroscopic, isotope and Uniform distribution of p-process modeling techniques to reveal the fate 174Hf in extraterrestrial materials 1,2, 1,2 of sulphur in petroleum system STEFAN T.M. PETERS *, CARSTEN MÜNKER studies 1Institut für Geologie und Mineralogie, Universität zu Köln, 1* 1 2 Germany; [email protected] (* presenting author) HENNING PETERS , OLAF PODLAHA , CHAD GLEMSER , 2 2 1 Steinmann-Institut für Geologie, Mineralogie und Paläontologie, LAVERN STASIUK AND ERDEM IDIZ Rheinische Friedrich-Wilhelms-Universität Bonn, Germany 1Shell Global Solutions International B.V., Rijswijk, The Netherlands, Nucleosynthetic heterogeneity in extraterrestrial materials is [email protected] (* presenting author) found for several (but not all) p-process isotopes, and reflects the [email protected] injection of material synthesized by at least one supernova event [email protected] shortly before the first solar system objects formed. Further 2Shell Canada Energy LTD, Calgary, Canada information on the distribution of p-process isotopes is relevant to [email protected] characterise the source of this “late injection” and to unravel the [email protected] different nucleosynthetic processes producing p-process isotopes. Here we present high precision MC-ICPMS measurements of p- Introduction process isotope 174Hf in silicate materials that have originated at The subsurface geochemical distribution of non-hydrocarbon different ages and from different regions within the inner solar “sour” gases (H2S, CO2) in oil/gas reservoirs is controlled mainly system. 174Hf is of particular interest because of its similar mass by thermochemical sulphate reduction (TSR) and organic matter range to p-process 180W, which displays large excesses in iron cracking of organic sulfur compounds (OSC) in high temperature meteorites [1]. reservoirs versus bacterial sulfate reduction (BSR) in low- For Hf purification, we optimised the existing protocol by [2]. temperature reservoirs [1]. Their subsequent interactions with the This was necessary to (1) successfully correct for the interference hydrocarbon phase yield organic sulfur compounds in reservoirs and by isobaric 174Yb; and (2) avoid matrix effects. Furthermore, we can result in sulfur rich bitumen formation via natural vulcanization extensively tested sample cones with a large aperture (“Jet cones”) processes [2]-[4]. in combination with an OnToolTM Booster interface pump. This To elucidate such mechanisms as sulfur incorporation and setup enhances instrument sensitivity by a factor of more than 5 (ca. bitumen formation, we developed an integrated experimental 3000 V/ppm Hf), but we also observed anomalous mass bias approach of organic/inorganic geochemical and spectroscopy behavior in the presence of only minute amounts of matrix. All methods combined with in-house modeling capabilities. With samples were therefore measured in setup with standard sample and presenting the main elements of the analytical workflow involving X-skimmer cone, typically consuming ~60 ng Hf at precisions of bulk geochemical data, X-ray absorption and photoelexctron ±70 ppm (2V). spectroscopy techniques, isotope geochemistry, fluid inclusion 174Hf/177Hf ratios in analysed EL, H, L and CV chondrites, studies and modeling approaches, we aim for a profound eucrites, and one lodranite sample are indistinguishable from the understanding of gas/fluid-rock interactions involving sulfur terrestrial value. In contrast, a silicate inclusion of the El Taco IAB geochemistry in the suburface realm. iron meteorite and one EL6 chondrite (Pillistfer) exhibit higher The workflow was developed on stacked Upper Devonian to 174Hf/177Hf ratios than the terrestrial standard, namely 190 ±72 ppm Mississippian sour gas reservoirs situated in the Rocky Mountains and 210 ±75 ppm respectively. These are correlated with higher Foothills of Alberta, Western Canadian Sedimentary Basin (WCSB), 178Hf/177Hf ratios (18±5 and 21±5 ppm, respectively). The latter Canada. Production from these reservoir units is mainly dry gas and most likely result from secondary neutron capture reactions at

condensates with different forms of sulfur. H2S contents range from epithermal energies due to the high Fe content of the samples [3]. 5% to almost 90%. The high 174Hf/177Hf ratios therefore most likely reflect a deficit in 177Hf. 174Hf itself has a low neutron capture cross-section (RI ~345 Results and Conclusions barn [4]) and is expected to be unaffected by cosmic ray Preliminary data on studied bitumens from WCSB assets interactions. revealed a sequence of solid bitumens with increasing amounts of The absence of nucleosynthetic heterogeneity in 174Hf indicates sulfur incorporated. The distribution of sulfur compounds in the that either the protosolar nebula was homogenous in 174Hf, or, bitumen matrix comprises various oxidation states from -2 to +6. alternatively, that existing 174Hf heterogeneities had been efficiently Major sulfur compound classes quantified are sulfide bridged homogenized by the time of parent body formation. The second compound classes, thiols, thiophenes and sulfates. scenario would be consistent with a single source for p-process 180W and 174Hf, and is therefore more plausible.

[1] Machel (2001) Sed. Geol. 140, 143-175. [1] Schulz & Münker (2011) Mineral Mag 75, 1827. [2] Münker et [2] Kelemen et al. (2010) GCA 74, 5305-5332. al. (2001) G3 2, GC000183. [3] Sprung et al. (2011) EPSL 295, 1- [3] Kelemen et al. (2008) GCA 72, 1137-1143. 11. [4] Trbovich et al. (2009) Nucl Sc Eng 161, 303-320. [4] Walters et al. (2011) Organic Geochem. 42, 999-1006

Mineralogical Magazine | www.minersoc.org 2224 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts

Multi tracer study (36Cl, 234U/238U, A structure refinement for 14C) of the Tunisian Continental monoclinic hydrohematite

Intercalaire: inferring recharge KRISTINA M. PETERSON1*, PETER J. HEANEY2 AND JEFFREY E. 3 areas and groundwater ages. POST 1Pennsylvania State University, Department of Geosciences, J. O. PETERSEN1,*, P. DESCHAMPS1, B. HAMELIN1, J. University Park, USA, [email protected] (* presenting author) GONCALVES1 , M. MASSAULT2, J.-L. MICHELOT2 AND K. 2Pennsylvania State University, Department of Geosciences, ZOUARI3. University Park, USA, [email protected] 1 CEREGE, UMR Aix-Marseille Univ.-CNRS-IRD, Aix-en-Provence 3Department of Mineral Sciences, Smithsonian Institution, USA, cedex 4, France (* correspondence: [email protected]) [email protected] 2 IDES, Université Paris-Sud, Orsay, France 3 LRAE (ENIS), Sfax Univerty, Sfax,Tunisia Introduction In ferruginous soils, nano- to micro-scale hematite (α-Fe2O3) Assessment of groundwater recharge and ages is critical to study plays a central role in redox processes and contaminant cycling. - the sustainability of groundwater resources. However, determining Hematite is known to incorporate structural OH and water, and the “active” recharge areas within large aquifer systems, such as the requisite charge balance is achieved by iron vacancies. Prior North-Western Sahara Aquifer System (NWSAS) remains researchers have suggested that the defective hematite structures form challenging. Here, we combine three geochemical tracers (14C, 36Cl unique phases called “protohematite” (PH) and “hydrohematite” and U isotopes) to infer past or recent recharge and evaluate (HH) [1-3]. These phases are distinguished from stoichiometric groundwater ages in the Tunisian Continental Intercalaire (CI) hematite (SH) by their degree of hydration and iron deficiency. Aquifer, the confined aquifer unit of the NWSAS. Furthermore, past infrared and Raman spectroscopic studies have Thirty-two boreholes were sampled, covering the whole Tunisian assigned a lower-symmetry space group to PH/HH (R3c) relative to part of the CI aquifer. We paid a special attention on the Dahar that of SH (R-3c) [4]. However, the existence and structure of these Mountains where CI formations outcrop (11 samples). Only two phases has been contentious, largely due to the lack of in situ X-ray samples located in the Northern Dahar are significantly above diffraction data [5]. background in 14C activity (1 pmc and 1.1 pmc). Uranium content Here we present a new structure refinement for HH in a varies from 2.8 to 5u -4 ppb and 234U/238U activity ratio from 1 to monoclinic space group (I2/a) using time-resolved X-ray diffraction 14. The stepwise decrease in U concentration goes with a high (TR-XRD) data collected at the Advanced Photon Source (APS). increase of the 234U/238U ratio followed by a decrease, clearly Starting with ferric chloride solutions, we collected TR-XRD data indicating the occurrence of a redox front. 36Cl/Cl ratio varies from 5 during the in situ hydrothermal precipitation of akaganéite and its u -15. Four samples in the upper range (35-40 u -15) are transformation to HH. Sealed quartz capillaries (1.0 mm diameter) again located in the northern oxidizing region of the Dahar as were heated at 200 °C while XRD data were collected every 25 – 30 revealed by U concentration. Therefore, these data all converge to seconds. Rietveld refinements suggested a new monoclinic HH indicate that mixing with recent recharge waters occur to some extent structure. in the northern Dahar region, while the southern part of this region shows no evidence of recent recharge. Results and Conclusions This constitutes valuable information for hydrodynamic model In our experiments, distinct peak splitting was observed in the and comparison with direct simulation of groundwater age (e.g. age- hematite diffraction patterns, indicating a violation of the 3-fold mass approach). We will assess at the meeting the consistency of rotational symmetry. The observed peak splitting in our data was these data with flow lines of water circulation inferred from outside the range calculated for sample displacement, and piezometric data and hydrological modelling. Crude time constraints furthermore video footage obtained during the reaction showed and mixing ratios will be also estimated from the comparison particles uniformly convecting throughout the volume of the between these samples and those collected from the shallower capillary. We therefore refined the structure in the various subgroups Continental Terminal (CT) aquifer closer to present-day recharge of R-3c. As the fit using I2/a was statistically no worse than that in waters. lower symmetry groups, we selected this space group for our refinement. A monoclinic unit cell with parameters of a = 13.7493(15) Å, b = 5.0121(4) Å, c = 5.4418(6) Å, β = 147.6250(17)° 2 provided a good fit and significant reduction in χ and Rwp relative to S.G. R-3c. Our results demonstrate that the in situ formation of the defective hematite phase, HH, was successfully captured. Moreover, HH is structurally distinct from SH and may form as a lower- symmetry monoclinic phase in soils.

[1] Dang et al. (1998) Hyperfine Interact. 117, 271-319. [2] Wolska (1981) Z Kristallogr. 154, 69-75. [3] Gualtieri and Venturelli (1999) Am. Mineral. 84, 895-904. [4] Burgina et al. (2000) J. Struct. Chem. 41, 396-402. [5] Cornell and Schwertmann The Iron Oxides, 2nd ed. Wiley-VCH, Weinheim (2003).

Mineralogical Magazine | www.minersoc.org 2225 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts The microbial role in diagenetic Simulating fluoride evolution in groundwater using a reactive dolomite formation multicomponent transient transport DANIEL A. PETRASH1* AND KURT O. KONHAUSER1 model 1* 1,2 1 1University of Alberta, Edmonton, Canada, [email protected] (* PETTENATI MARIE , PERRIN JEROME , PAUWELS HÉLÈNE , 2,3 presenting author) AND SHAKEEL AHMED 1BRGM, Avenue Claude Guillemin, BP 36009, 45060 Orléans In the Neogene, the presence of extensive dolomite intervals Cedex 02, France, [email protected] (* presenting author) 13 exhibiting multigenetic crystal morphologies, distinctive δ C 2IFCGR, Indo-French Center for Ground Water Research, NGRI, signatures and variable concentrations of Fe and Mn, strongly suggest Uppal Road, 500 007 Hyderabad, India 3 the involvement of various microbial heterotrophic pathways in both NGRI, Uppal Road, 500 007 Hyderabad, India

dolomite nucleation and ageing [1,2]. However, the relevance of Overexploitation of crystalline aquifers in a semi-arid climate enhanced organic burial, and the catalytic role of microbes in post- leads to a degradation of water quality. The Maheshwaram watershed depositional dolomite formation, and as an overall control of the is a typical Southern India rural watershed, with intensive groundwater abstraction (more than 700 productive irrigation wells), Cenozoic abundance of dolomite, remains to be demonstrated. and a predominant paddy field cropping pattern [1-2]. We outline the Most recently, the anaerobic oxidation of methane (AOM), process of F accumulation in this small endorheic watershed [3] typically by a consortium involving archaea and sulfate reducer where the groundwater has a high fluoride concentration of up to 4 -1 -1 bacteria, has been found to be a significant geochemical process in mg l (WHO guideline value <1.5 mg l ). The main processes responsible for the observed salt loads are probably being due marine sediments [3,4,5]. The activity of microbial communities mainly to irrigation return flow (IRF) and a high evaporation rate [4]. capable of AOM is usually recorded by a distinctively depleted A solute recycling model that includes water/rock interactions 13C signal in their carbonate by-products [3]. However, in diffusion- and climatic parameters was used to assess the processes dominated sediments more positive δ13C could be the result of an controlling fluoride contamination in a crystalline aquifer intensively exploited for paddy field irrigation. we used a 1D admixture of methanogenic 13CO , or alternatively from extensive 2 PHREEQC reactive-transport column [5] to conceptualize the AOM, which may also increase the residual carbon pool in 13C [5]. In infiltration of paddy field IRF under watershed-scale evaporation Neogene sequences, the occurrence of multigenic dolomite-rich conditions. Increase of F- in IRF caused by evaporation and mineral intervals with δ13C varying from markedly negative to positive values dissolution (no fertilizer input) leads to the accumulation of F- in points to AOM as a likely mechanism of ageing, and potentially the aquifer. Crystalline aquifer overexploitation in semi-arid areas extends the microbial dolomite induction zone a few hundred meters enhances geogenic pollution derived from the dissolution of below the sediment water interface [e.g., ref. 4]. fluoride-bearing minerals (fluorapatite, allanite, biotite) through a combination of complex hydrochemical processes [6]. The present To fully understand the burial diagenetic history of such model aims to provide a robust method for the development of intervals, and by extrapolation, their ancient analogues, a prediction tools dedicated to aquifer management in this specific comprehensive analytical approach is required. For instance, in context. addition to the possible presence of 13C-depleted lipid biomarkers [3],

when compared with their near-surface precursors dolomite cements

formed under the influence of syntrophic AOM should exhibit [1] Kumar and Ahmed (2003,) Curr. Sci. 84, 188-196. relatively higher Fe, Mn, and probably bioactive Ni, Zn and Cu [2] Maréchal et al., (2006) J. Hydrol. 329, 281-293. [3] Négrel et al., (2011) J. Hydr. 397, 55-70. concentrations [6]. Unravelling the role of AOM in dolomite [4] Perrin et al., (2011) J. Hydrol. 398, 144–154. formation during burial into the methanogenic zone may provide new [5] Parkhurst and Appelo (1999) J. Hydrol. 398, 144–154. [6] Pettenati et al., (2012) Appl. Geochem., submitted. insights into the long-standing dolomite problem.

[1] Budd (1997) Earth Science Reviews 42,1-47. [2] Mazzullo (2000) Journal of Sedimentary Research 70, 10-23. [3] Thiel et al. (2001) Marine Chemistry 73, 97-112. [4] Roussel et al. (2008) Science 320, 1046. [5] Alperin and Hoehler (2010) American Journal of Science 309, 958-984. [6] Valentine and Lippard (1997) Journal of the Chemical Society, Dalton Transactions 21, 3925-3932.

Mineralogical Magazine | www.minersoc.org 2226 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Metals and microbes: imaging Investigating controls on chemical organic matter-mineral relationships weathering in the Cascade at high resolution with Mountains, Oregon 1* 1 1 STXM/NanoSIMS JULIE C. PETT-RIDGE WILL KRETT , NICK CURCIO , AND 1 1* 1,2 MARKUS KLEBER JENNIFER PETT-RIDGE , MARCO KEILUWEIT , JEREMY 1 3 1 BOUGOURE , PETER S. NICO , PETER K. WEBER , LYDIA 1Oregon State University Faculty of Soil Science, Corvallis OR, 2 2 2 ZEGLIN , DAVID D. MYROLD , MARKUS KLEBER USA, [email protected]

1Lawrence Livermore National Laboratory, Physical and Life The steep volcanic terrain of the wet western side of the Sciences Directorate, Livermore, CA (*[email protected]) Cascade Range is likely to support relatively fast weathering rates. 2 Department of Crop and Soil Science, Soils Division, Oregon State In this study we present data from a weathering study at H.J. Andrews University, Corvallis, OR Experimental Forest in the western Oregon Cascades. Our goal is to 3 Lawrence Berkeley National Laboratory, Earth Sciences Division, Berkeley, CA better understand controls on weathering processes, namely the controls on secondary mineral formation and on the magnitude of Advancing understanding of soil organic-mineral interactions streamwater dissolved silica fluxes. requires disentangling the complex interactions between soil Controls on both temporal and spatial variability of streamwater mineral surfaces, decomposed organic compounds, and soil silcia fluxes are investigated using 40+ year streamwater chemistry microbes in structurally intact soil. To avoid method-related records from 7 small gauged watersheds within the site, and using artifacts that are associated with the common physical soil synoptic sampling data from 40 locations across the site sampled in fractionation techniques, non-invasive high-resolution imaging 1 day under baseflow conditions. Three sets of paired watersheds techniques have been recently developed to simultaneously with contrasting land-use treatments (control, clear-cut, partial determine the molecular composition, source and fate of added OM, timber harvest, road building) but similar topography, aspect, and location of OM within soil micro-aggregates. Simultaneous bedrock and vegetation do not reveal significant land-use effects on high-resolution chemical characterization and isotope tracing can be streamwater silica fluxes. Over two orders of magnitude variation achieved by combining nano-scale imaging mass spectrometry in instantaneous streamwater silica fluxes across the site is observed (NanoSIMS) and spatially resolved spectroscopy (STXM/NEXAFS). in the synoptic sampling. Stream temperature and landscape These techniques allow precise, high-resolution, quantitative position correlate with silica flux, suggesting that deeper hydrologic measurement of molecular and isotopic patterns in an undisturbed flowpaths are the source of high silica fluxes. sample. 10 soil pits were excavated, sampled, and characterized for In a series of recent experiments, we combined these techniques to physical and chemical properties including clay mineral XRD map organic carbon distribution, and image associations of organics analyses and selective chemical dissolutions. Paired pits were sited with specific metal-oxide minerals in soil. In these experiments, we to compare effects of slope aspect, bedrock type, and elevation. We used 15N- and 13C-organic matter incubations and NanoSIMS found that higher elevation soils that experience more permanent imaging to track the fate of specific microbial and plant polymers. winter snowpack contained smaller fractions of crystalline Fe- This has allowed us to measure preferential OM associations with Fe (hydr)oxides and larger fractions of organo-metal complexes and Mn oxides and clay particles. Using synchrotron-based scanning relative to lower elavation soils. Among lower elevation soils, transmission X-ray microscopy (STXM) analysis of the same neither slope aspect (which corresponds to 30% difference in soil microstructures, we can then measure the molecular class of these water flux), nor bedrock type (basalt versus andesitic breccia and particles, for example, thin amine N coatings covering Fe tuff) varied consistently with soil properties. In this steep (hydr)oxides, and microbial lipids coating montmorillonite mountainous terrain (average slope 60-70%), geomorphic factors particles. such as creep and treethrow appear to play a dominant role in These high-resolution imaging approaches are complementary to controlling the degree of soil profile development. more traditional bulk analyses (14C dating, NMR, density Using this and previous data from the well-characterized H.J. fractionation) and can yield mechanistic explanations for proceses Andrews study site, we evaluate weathering processes observed at which influence organic matter decomposition in soil. both soil pit and small watershed scale in the larger context of This work was performed under the auspices of the U.S. Department controls on weathering. Specifically, we evaluate the role of climate of Energy by Lawrence Livermore National Laboratory under variables (runoff, temperature, and snowpack persistence), Contract DE-AC52-07NA27344. topography, erosion rate, and hydrologic variables (soil water flux and distributions of fluid residence time) in controlling weathering fluxes as proposed in recent studies.

Mineralogical Magazine | www.minersoc.org 2227 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts The osmium isotope record of seawater: 20 years of research Does the naturally elevated sulfur 1* 2 content of Ulva lactuca play a role in BERNHARD PEUCKER-EHRENBRINK AND GREG RAVIZZA the uptake and speciation of arsenic? 1Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA CATHERINE PHAM1, 2*, LAURENT CHARLET2, AND GARRISON [email protected] (*presenting author) SPOSITO1 2Department of Geology and Geophysics, SOEST, University of 1University of California, Department of Environmental Science, Hawaii at Manoa, Hawaii, HI, USA Policy & Management, Berkeley, United States, [email protected] [email protected] (* presenting author),

187 188 [email protected] Secular variations in the Os/ Os of seawater were 2 discovered twenty years ago [1]. Since then, significant progress has Université de Grenoble, Institut des Sciences de la Terre, Grenoble, been made towards reconstructing 187Os/188Os variations throughout France, [email protected] the Cenozoic, and select time intervals in the Mesozoic and Palaeozoic. Algae are ubiquitous in surface waters and are known to Osmium is an ultra-trace element in seawater with a residence influence the chemodynamics of the priority toxic metalloid, arsenic time of less than 50,000 years, and possibly as short as a few (As), in polluted marine environments. Marine algae initially thousand years. While initially thought to be well mixed throughout transform As(V) to As(III), after which As(III) is methylated and then the oceans, high-precision data – including in the modern ocean - have indicated spatial variations of the order of a few percent. The converted to a diverse set of organoarsenic compounds by residence time of osmium makes the isotope system not only mechanisms that remain unclear.[1] Recently it has become evident ideally suited for tracing processes on time scales of glacial- that the common marine green alga Ulva lactuca contains elevated interglacial variations, but also for investigating longer, tectonically levels of sulfur (S) and has the capacity to generate toxic driven changes on the Earth’s surface. concentrations of H2S in the presence of excess nitrates. In light of Osmium is enriched in marine sediments that have been the fact that As is chalcophilic, it is important to understand the deposited under reducing, and - to a lesser extent – oxic, conditions. interaction between As, S, and nitrates in Ulva lactuca because the In such sediments, variations in its isotope composition - recorded as 187Os/188Os - have left a rich archive that reflects changes on the algae may serve as an As reservoir and pose an emerging threat to Earth’s surface. The affiliation of osmium with sedimentary organic coastal environments where nitrate inputs are increasing. matter makes the marine 187Os/188Os record a sensitive indicator of In the present study, using synchrotron-based X-ray absorption cycling of old sedimentary organic matter. The lack of a buffering spectroscopy and X-ray microfluorescence mapping, we investigated mechanism similar to the formation and weathering of marine the bioavailability and chemical speciation of As in Ulva lactuca 87 86 carbonates in the Sr/ Sr record of seawater leads to variations that sampled from contaminated coastal waters in order to understand As span most of the range in isotope variations between geochemical cycling in the marine environment. We also conducted batch culture endmembers. Here we focus on the most highly resolved events in the experiments with Ulva lactuca to explore the role of thiolation in As Cenozoic and Mesozoic that are reviewed in detail in the soon to be biotransformation and toxicity. published chapter 8 in the Geologic Time Scale 2012 [2]. These Using X-ray microfluorescence mapping, we observed trends in events fall into two categories: transient excursions to more the distribution of S along the thallus of Ulva lactuca. We are radiogenic values that are thought to be caused primarily by investigating whether the As distribution and concentration may be hyperthermal events (e.g. PETM), and transient excursions to less correlated with areas of elevated S content along the thallus. Using radiogenic values that are caused by extraterrestrial impacts (e.g. synchrotron-based X-ray absorption spectroscopy, we characterized KTB, late Eocene impacts), large volcanic eruptions (e.g., CAMP, Deccan, and Yemeni-Ethiopian flood basalts), or erosion of the complexation of As with S moities in environmental samples osmium-rich, unradiogenic lithologies at convergent plate margins collected from industrially-polluted sites. (e.g. erosion of the Papuan ophiolite in the late Eocene). Our research aims to determine the potential risks As may pose Widespread anoxia may lead to rapid removal of osmium from to both aquatic ecosystem and human health as it is transformed into the water column, thereby generating conditions for the various chemical forms and moves from algae up trophic levels, predominance of local fluxes to seawater in an isotopically non- potentially to fish and humans. homogenous water column (e.g. Ocean Anoxic Events in the

Mesozoic). In addition, the isolation and reconnection of ocean [1] Edmonds, JS and Francesconi, KA (1977) Nature 265, 436. basins to the global circulation may leave an isotope fingerprint if inputs to such basins deviate from the globally averaged input of osmium to seawater (e.g. Arctic Ocean).

[1] Pegram et al. (1992) EPSL 113, 569-576. [2] Peucker-Ehrenbrink and Ravizza (2012) Geologic Time Scale 2012, Chapter 8: Osmium isotope stratigraphy (Gradstein et al., Eds.), doi: 10.1016/B978-0-444-59425-9.00008-1.

Mineralogical Magazine | www.minersoc.org 2228 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Isotopic constraints on the genesis of Natural gas leaks in Boston basanitic lavas beneath Haleakala 1* 2 3 NATHAN G. PHILLIPS , ROBERT ACKLEY , ERIC CROSSON , 1* 1 4 4 4 ERIN H. PHILLIPS WRITER , KENNETH W.W. SIMS , VINCENT ADRIAN DOWN , JON KARR , AND ROBERT B. JACKSON 2 J.M. SALTERS 1Boston University, Boston, USA, [email protected] (* presenting 1University of Wyoming, Department of Geology and Geophysics, author) Laramie, WY, USA, [email protected] (* presenting author), 2Gas Safety, Inc., Southborough, USA, [email protected] [email protected] 3Picarro, Inc, Santa Clara, USA, [email protected] 2Florida State University, Department of Geological Sciences, 4Duke University, Durham, USA, [email protected], Tallahassee, FL, USA, [email protected] [email protected], [email protected]

Although tholeiitic volcanism is predominant in Hawaii, the Introduction and Methods study of smaller volume, late-stage alkaline volcanism is imperative There are large uncertainties in the fate of lost and unaccounted to understanding the magmatic history of the Hawaiian Islands and gas from the natural gas process chain, including in distribution the dynamics of mantle plumes. Recent basanitic lavas from pipeline systems [1,2]. To assess the spatial pattern and typical leak Haleakala represent an end-member in the compositional range of rate of natural gas leaks in an urban distribution system, we drove Hawaiian lavas and are hypothesized to tap magma from the fringe of and mapped leaks on the 785 centerline road miles in the City of Boston. We used a GPS-equipped cavity ringdown methane analyzer, the Hawaiian plume [1]. Indeed solid mantle upwelling rates inferred sampling the air above road surfaces. Additionally, to assess leak from U-series data from a limited number of samples from rates, we deployed gas accumulation chamber on 25 representative Haleakala [1] are consistent with both iso-viscous and thermo- gas leaks. Finally, we identified sources of methane leaks using viscous fluid mechanical models of plume upwelling [2,3]. carbon isotope analysis and human olfactory detection of the However, these conclusions were based on a very small data set odorant mercaptan, which is added to pipeline gas. (5 samples) and additional isotopic data on alkaline lavas are essential for a more complete understanding of the genesis of late stage and rejuvenated stage volcanism. We present Hf, Nd, Sr, and Pb isotopic data, 238U-230Th and 235U-231Pa-227Ac and major and trace-element data for a suite of 13 samples from Haleakala crater. These samples are relatively young, with 14C ages ranging from 870 ± 40 to 4070 ± 50 years [4]. They are nepheline normative and LREE enriched, indicating that they represent small degree melts. Relative to main-stage tholeiites (Kilauea and Mauna Loa) and late- stage alkali basalts (Mauna Kea and Hualalai), the Haleakala crater Figure 1: Methane leaks from natural gas pipelines in the samples come from a relatively depleted source (εNd = 7.37-8.60; Beacon Hill neighborhood of Boston. Yellow bars represent 87 86 Sr/ Sr = 0.70314-0.70333; εHf = 12.66-14.68). All samples have methane concentrations in parts per million; the highest values 230 238 Th/ U >1 indicating that they originate from a source containing recorded exceed 15 times background levels. residual garnet. Consistent with earlier studies, the 230Th/ 238U

(1.19-1.32) and 231Pa/235U (1.65-1.79) of these samples are much Results and Conclusions higher than other young Hawaiian lavas suggesting that basanitic We detected ca. 3,900 distinct elevated methane sources within lavas from Haleakala are the manifestation of a small degree of the City of Boston. Isotopic and olfactory methods indicate that a partial melting and relatively slow mantle upwelling rates. majority of these methane sources are associated with the natural gas pipeline distrib ution system. Individual leak rates ranged from 28 cubic feet per day (CFD) to 315 CFD, averaging 110 CFD, more [1] Sims et al. (1999) Geochim. Cosmochim. Acta, 63, 4119-4138. than half daily US household natural gas use. We conclude that the [2] Hauri et al. (1994) Jour. Geophys. Res., 99, 24,275-24,300. [3] magnitude of gas lost by typical leaks and their frequency in urban Watson and McKenzie (1991) J. Pet., 32, 501-537 [4] Sherrod and areas like Boston have potential to amount to substantial total lost McGeehin (1999) USGS Open-File Report 99-143, 14pp. natural gas. The magnitude of lost and unaccounted gas [1] can represent several percent and more of typical total state greenhouse gas inventories, and total more than $1B nationally. Our discovery of widespread urban gas leaks provides impetus for concerted efforts to determine the total leak rate and corresponding greenhouse warming potential from natural gas distribution systems.

[1] Energy Information Administration, form EIA-176 (2010). [2] Howarth et al. (2011) Climatic Change 106, 679-690.

Mineralogical Magazine | www.minersoc.org 2229 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Opening the black box: Imaging Direct Mass Spectrometric Analysis nanoparticle transport through rock of Position Specific δ13C in Organics

with MRI ALISON PIASECKI 1*, JOHN EILER1 1* 1 VERNON PHOENIX , SUSITHRA LAKSHMANAN , WILLIAM 1 California Institute of Technology, Pasadena CA, USA, 2 3 SLOAN , WILLIAM HOLMES . [email protected] (*presenting author)

1University of Glasgow, Geographical and Earth Sciences, Glasgow, It is recognized that natural organic molecules can exhibit UK, [email protected] (* presenting author) position-specific isotopic fractionations (i.e., differences in isotopic 2University of Glasgow, Infrastructure and Environment, Glasgow, composition for a single element between non-equivalent molecular UK, [email protected] sites). For example, lipids can exhibit up to ~30 ‰ difference in 3University of Glasgow, Wellcome Surgical Institute, Glasgow, UK, 13C/12C between adjacent carbons as a result of fractionations arising [email protected] during decarboxylation of pyruvate in lipid biosynthesis [1]. Little in Introduction detail is known about such isotope effects in natural products, but it Magnetic Resonance Imaging (MRI) is perhaps best known for seems possible that observations of isotopic ordering of carbon could its use in medicine. However, its ability to non-invasivly image distinguishing among the mechanisms and conditions of biosynthetic inside materials that are opaque to other imaging methods is of reactions. And, such position specific isotope effects may be inherited benefit to the geological and environmental sciences. Here we by alkanes produced from thermal degredation fatty acid chains, report on the application of MRI to image transport of nanoparticles perhaps modified as functions of the conditions and mechanisms of through sandstone. This approach is beneficial as it enables 2D and thermal maturation. 3D ‘videos’ of nanoparticle transport inside rock to be collected, Here we examine the potential of the MAT 253 Ultra, a new kind providing spatially resolved data from which we can enhance our of high resolution gas source isotope ratio mass spectrometer [2], to understanding of nanoparticle transport in groundwater systems. make measurements that will permit reconstruction of position specific carbon isotope compositions in organic molecules, as Methods preserved in alkanes. We focus on propane, the smallest alkane that Commercially available nano-magnetite nanoparticles with an could exhibit position specific carbon isotope differences. Electron impact ionization of propane yields three families of product ions: organic polymer cap were used. The superparamagnetic nature of C1Hn, C2Hn and C3Hn; fragments made by H loss are abundant, these nanoparticles ensured they were visible to MRI. These were including bare carbon ions and clusters. H adducts are present but pumped through bentheimer sandstone rock core and MR images rare. An analysis of the 13C/12C ratio of any two of these familes of were collected every 5 minutes. Images were calibrated to maps of product ions constrains the position specific C isotope fractionation in actual nanoparticle concentration using the MRI parameter T2 (the 1 propane, provided such fragment species can be analyzed stably and spin-spin relaxation of H nuclei), as 1/T2 is proportional to reproducibly and one has accounted for exchange through nanoparticle concentration. recombination. We have demonstrated that 13CH3/12CH , 3 13 12 12 13 12 12 Results and conclusion C CH4/ C2H4, and C C2H8/ C3H8 ratios can be analyzed with sub-per mil precision (as good as 0.1 ‰ for the most abundant Transport of positive and negativly charged nanoparticles were species), and zero-enrichments yeild accurate results. It remains to be succesfully imaged, with transport of positivly charged nanoparticles seen whether this approach accurately reproduces independently retarded significantly due to electrostatic attraction to quartz known position-specific isotopic differences, though the low surfaces. Images collected after flushing with nanoparticle free abundance of adducts suggests recombination will not be a significant water showed negative nanoparticles were sucesfully removed from artifact; i.e., accuracies similar to the precisions reported here are the sandstone, while significant quantities of positive nanoparticles expected. remained. Concentration profiles were evaluated with CXTFIT and colloid filtration theory at regular distances along the length of the sandstone core to test for variations in dispersivity, dispersion coefficient, recovery, deposition rate constant, collision efficiency and transport –attachment efficiency. MRI’s ability to collect spatially resolved data ensures it can act as a useful tool to unpick nanoparticle transport heterogeneity and test and develop transport models.

Figure 1: Full spectra of propane as measured on MAT253-Ultra [1] DeNiro, Epstein (1977) Science Volume 197, 261-263. [2] Eiler et. al (2012) this volume.

Mineralogical Magazine | www.minersoc.org 2230 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Petrogenesis of alkaline mafic rocks Reduction of biogenic and abiogenic from Sivas, Central Anatolia: New Fe(III) minerals by humic substances 1* 2 insight into ancient continental ANNETTE PIEPENBROCK ,IRIS BAUER , AND ANDREAS 2 assembly and break-up KAPPLER 1University of Tuebingen, Center for Applied Geosciences, 1* 1 MEGAN PICKARD , TANYA FURMAN , BILTAN Tuebingen, Germany, [email protected] 2 3 3 KÜRKCÜOGLU , BARRY HANAN , KAAN SAYIT tuebingen.de (* presenting author) 2 1Department of Geosciences, Pennsylvania State University, University of Tuebingen, Center for Applied Geosciences, University Park, PA, USA, [email protected] (* presenting Tuebingen, Germany, [email protected] author), [email protected] 2Department of Geological Engineering, Hacettepe University, Humic substances (HS) have been shown to shuttle electrons

Ankara, Turkey, [email protected] between microorganisms and poorly soluble electron acceptors such 3 Department of Geological Sciences, San Diego State University, as Fe(III) minerals. HS can be reduced by a wide variety of San Diego, CA, USA, [email protected], microorganisms including Fe(III)-reducing, sulfate-reducing and [email protected] dechlorinating bacteria, but also chemically for example by sulfide. In contrast to the reduction of the HS, the second electron transfer step Alkaline mafic lavas are a common feature of intraplate from reduced HS to the Fe(III) minerals proceeds abiotically and is extensional volcanic settings. We examine mafic lavas from Sivas, controlled mainly by the properties of the Fe(III) minerals, such as Central Anatolia, in order to understand controls on their genesis in their redox potential. The electron transfer from HS to the Fe(III) a setting with a complex tectonic history extending over the past 1.3 minerals is rate limiting for the whole electron shuttling process, but billion years. Continental assembly and break-up, both associated only little is known about the dynamics and limitations of this second with geochemical modifications to the associated lithosphere, has long played a significant role in Anatolia. The present tectonic electron transfer step itself. This is in particular the case since most regime consists of a complex juxtaposition of rift, strike-slip, and laboratry studies were carried out under geochemical conditions transtensional faulting and an overall WSW movement of the differing significantly from those typically encountered in the continental microplate. environment. Thus, the importance of humic substances as electron We identify two groups of alkaline lavas that record shuttles under environmental conditions is currently unknown. different petrogenetic histories. Select incompatible trace element To elucidate some of the remaining questions, we aimed to variations (e.g., Ti, Zr) indicate that abundant basalts and basaltic quantify the rate and extent of electron transfer between reduced and andesites (BBA) evolved by fractional crystallization of a non-reduced HS and various Fe(III) minerals. We focused, in frequently-erupted parental magma with ~9 wt.% MgO. The BBA particular, on the difference between reduction of biogenic vs. lavas have overall smooth primitive mantle normalized incompatible trace element patterns that suggest derivation from a source region abiogenic Fe(III) minerals by HS. Our studies showed that more geochemically similar to that of ocean island basalts. In contrast, electrons were transferred from chemically reduced HS to biogenic basanites erupted over a small geographic area show little than compared to abiogenic Fe(III) minerals. Since biogenic and fractionation but rather represent individual magma batches with abiogenic Fe(III) mineral suspensions were normalized to the same different degrees of partial melting. These lavas exhibit enrichments BET surface area, it could be ruled out that this outcome resulted in Ba, Th, and U and depletions in Rb, Hf and Ti that are from a difference in specific surface area between the mineral characteristic of melts derived from metasomatized lithosphere. Pb suspensions. Furthermore, our results indicate that laboratory abundances in both groups are anomalously high, though this feature experiments with abiogenic Fe(III) minerals might significantly is more pronounced in the basanites, suggesting interaction with a underestimate the amount of electrons transferred between HS and Pb-rich continental component. In general, Sr-Nd-Hf radiogenic isotopic signatures of Fe(III) minerals and, as a result, they might also underestimate the the BBA lavas are less radiogenic than those measured in the importance of HS electron shuttling in environmental systems basanites. The BBA and basanite groups overlap in eNd-eHf isotope wherein minerals might be of mainly biogenic origin. This is of great space, plotting on and above the mantle array between data fields for importance, since electron transfer via humic substances has the oceanic basalt-like and continental lithosphere-like compositions. potential to contribute significantly to the electron fluxes in the 87 86 The least radiogenic BBA lavas ( Sr/ Sr 0.7040-0.7044; environment and thus might affect the fate of organic and inorganic 143 144 Nd/ Nd 0.51278-0.51280) approach compositions of pollutants. asthenospheric melts. Radiogenic Pb isotope compositions of both groups plot within the range of Indian MORB. Nd model ages of Sivas lavas are consistent with a DUPAL-like source region with Rodinia (~1.2 Ga) continental lithosphere affinity. The observation that basanitic lavas are found only to the southeast of a major strike- slip fault suggests that post-Miocene faulting either controls or reflects significant subsurface chemical heterogeneity related to topography across the lithosphere-asthenosphere boundary.

Mineralogical Magazine | www.minersoc.org 2231 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Evolution of the East Antarctic ice Solid-Solution Interfacial Reactions: sheet across the mid-Miocene climate Effect of Solution Saturation State

1* 2 transition based on ice-rafted detritus ERIC M PIERCE AND SEBASTIEN N KERISIT provenance studies 1Oak Ridge National Laboratory, Oak Ridge, TN, USA, 1* 2 1,3 [email protected] (* presenting author) E.L. PIERCE , T. VAN DE FLIERDT , S.R. HEMMING , T. 2 3 2 Pacific Northwest National Laboratory, Richland, WA, USA, WILLIAMS AND C. COOK [email protected] 1 Columbia University, New York, USA, [email protected] (* presenting author) Solid-solution interfacial reactions—specifically silica-rich 2 Imperial College, London, UK inorganic surface coatings—play a critical role in the evolution of 3 Lamont-Doherty Earth Observatory, Palisades, USA natural and engineered systems and the transport of radionuclides in the environment. For example, Nugent et al.[1] has shown that The Mid-Miocene Climate Transition (MMCT, ~14 Ma) development of silica-rich inorganic surface coatings form quickly is an interval of major climate reorganization, accompanied by on albite samples in the field and suggests the formation of these coatings are the reason for the discrepancy between laboratory and significant decreases in global temperatures and sea-level. During field measured weathering rates. Similar surface-layers have been this interval the East Antarctic Ice Sheet (EAIS) expanded to at least observed in weathering studies conducted with mineral-based 85% of its present volume, and may have transitioned from a wet- to glasses, French and Roman glass samples, and surrogate nuclear frozen-bed regime. The geology of East Antarctica exhibits a waste glasses[2,3,4]. Knowledge gaps in the fundamental understanding of alteration layer formation impede the ability to link distinct variation from the Ross Sea to Prydz Bay that allows for the macroscopic reaction kinetics to nanometer scale interfacial application of geochemical tracers to determine the provenance of processes that occur at the surface of mineral and glasses, especially ice rafted detritus (IRD) and identify EAIS sectors that supply IRD under near-saturated conditions. [1,2]. Prior work from ODP Site 1165 (Prydz Bay) indicates major Therefore to address the scientific challenge of deciphering the complex reactions controlling the formation and evolution of silica- ice-rafting events sourced from the Adélie and Wilkes margins from rich surface layers; a series of flow-through experiments were

late Miocene through early Pliocene, but not during the early conducted as a function of a[SiO2(aq)], from dilute to near-saturated Miocene (19-14 Ma) [3], indicating a change in EAIS dynamics and conditions with respect SiO2(am), at pH(23°C) = 9.0 and T = 90°C. IRD production from these margins through the MMCT. Results illustrate that as the saturation state of the solution increases the dissolution rate decreases by approximately two to three orders IODP Site U1356A, located off the coast of Adélie Land, of magnitude. Furthermore, analysis of reacted grains illustrate is well positioned to capture the signal of iceberg discharges from significant changes in the elemental composition and structure of this sector. Six peaks in the number of clasts >2mm between ~14.1- the hydrated-surface. In addition to the afore-mentioned experimental measurements, 13.2 Ma were identified from U1356A; samples were selected Monte Carlo simulations are being used to gain additional insight across each of these to represent peak, intermediate and low clast into the evolution of the elemental profiles. Recent advances to the counts. Samples were sieved at 150μm, the weight% >150μm was code developed by Kerisit and Pierce [5] enable visualization of the determined, and every hornblende grain >150μm was dated by history of the Si sites in a reacted glass sample to determine the origin of elements that comprise the hydrated-surface layer. 40Ar/ 39Ar. 40Ar/ 39Ar hornblende ages from each sample show a Although the data collected to-date provide key information on dominant population of 1400-1600 Ma, consistent with the Mertz the processes occuring at the glass-water interface, additional shear zone, but slightly younger than the coastal geology of Adélie experimentation and modeling will be required to develop a more Land (>1700 Ma), and indicating no significant sourcing of IRD robust understanding of these reactions.

from George V Land or the Ross Sea sector. Ongoing provenance [1] Nugent et al. (1998), Nature, 395, 588-591. work with 6 additional IRD peaks surrounding the original peaks is [2] Hamilton et al. (2001), GCA, 65, 3683-3702. [3] Pierce et al. (2007), Appl. Geo., 22, 1841-1859. underway to further evaluate EAIS evolution over the MMCT. [4] Verney-Carron et al. (2008), GCA, 72, 5372-5385. [5] Kerisit and Pierce (2011), GCA, 75, 5296-5309.

[1] Roy et al., (2007) Chemical Geology 244, 507-519 [2] Pierce et al., (2011) Paleoceanography 26 PA4217 [3] Williams (2010) EPSL 290, 351-361.

Mineralogical Magazine | www.minersoc.org 2232 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Voluminous magmas in intra- The origin of chemical heterogeneity continental setting: Hf and O isotopes in the Hawaiian mantle plume

in zircons from Late Paleozoic AARON J. PIETRUSZKA1* , MARC D. NORMAN2, MICHAEL O. volcanic rocks in NE Germany GARCIA3, JARED P. MARSKE1 AND DALE H. BURNS1 1San Diego State University, San Diego, CA, USA, 1* 2 [email protected] (* presenting author) PIETRANIK ANNA , CRAIG STOREY , BREITKREUZ 2 3 1 Australian National University, Canberra, Australia CHRISTOPH , ELŻBIETA DEJA 3University of Hawaii, Honolulu, HI, USA 1 University of Wrocław, Geological Sciences, Poland; [email protected] (* presenting author) Inter-shield differences in the composition of lavas from 2University of Portsmouth, Earth and Environmental Sciences, UK [email protected] Hawaiian volcanoes are generally thought to result from the melting 3TU Bergakademie Freiberg, Geology and Paleontology, Germany, of a heterogeneous mantle source containing variable amounts or [email protected] types of oceanic crust (sediment, basalt, and/or gabbro) that was recycled into the mantle at ancient subduction zones (e.g., [1-3]). Here we investigate the origin of chemical heterogeneity in the Voluminous rhyolitic rocks (ca. 34 000 km3) were formed in Hawaiian mantle plume by comparing the incompatible trace element the NE German Basin in an intra-continental setting ca. 300 Ma ago. abundances of tholeiitic basalts from (1) Kilauea, Mauna Loa, and εHf and G18O have been measured in dated magmatic and inherited Loihi Seamount (the three active Hawaiian volcanoes) and (2) the rhyolitic zircons from three drill cores across the NE German extinct Koolau shield (a compositional end member for Hawaiian Basin. Inherited zircons have crystallisation ages from ca. 1.7 to 0.5 volcanoes). Model calculations suggest that the mantle sources of Ga, εHf values of -20 to 7 ε units and G18O values of 5.8 to 9.3 ‰. Hawaiian volcanoes contain variable amounts of recycled oceanic The inherited zircons have Hf model ages of 1.9 - 2.2 Ga, indicating crust (ROC) from ~8-16% at Kilauea and Loihi to ~15-21% at Mauna that much of the basement was initially derived from the mantle at Loa and Koolau. We propose that the Hawaiian plume contains a that time. High G18O magmatic zircons have similar model ages package of ROC (basalt and gabbro, but little or no marine sediment) highlighting that the 300 Ma magmatic event involved the melting of that was altered by interaction with seawater or hydrothermal fluids sediments derived from basement generated at ca. 2.1 Ga. The εHf prior to being variably dehydrated in an ancient subduction zone. The values in magmatic zircons vary from -7 to +1 ε units and G18O = 6.0 ROC in the mantle source of Kilauea and Loihi lavas is dominated by to 9.4 ‰. The range of εHf and G18O values in magmatic zircons in the uppermost portion of the residual slab (gabbro-free and strongly the three sites investigated have been modelled by simple dehydrated), whereas the ROC in the mantle source of Mauna Loa assimilation - fractional crystallization processes of mantle derived and Koolau lavas is dominated by the lowermost portion of the magma contaminated by sediments with model ages of ca. 2.1 Ga. residual slab (gabbro-rich and weakly dehydrated). The model results Zircons record crystallization from magmas with 10-80 % mantle suggest that the large-scale distribution of compositional contribution, with an average of 45%. This implies that these silicic heterogeneities in the Hawaiian plume (at the present time) cannot be magmas contain on average 15000 km3 of mantle derived material described by either a radial zonation [1] or a bilateral asymmetry and that they represent a significant contribution to the net growth of [4,5]. Instead, the Hawaiian plume is heterogeneous on a small scale the continents. Zircons from the NE German Basin have more inter- with a NW-SE oriented spatial gradient in the amount, type (i.e., grain variability, but they record less complex magma evolution basalt vs. gabbro) and extent of dehydration of the ancient ROC. processes than zircon and whole rock data from other large silicic volcanic provinces, e.g. in North America. This is consistent with [1] Hauri (1996) Nature 382, 415-419. [2] Hofmann & Jochum zircon crystallizing in small magma batches, which are amalgamated (1996) J. Geophys. Res. 101, 11831-11839. [3] Huang & Frey (2005) in larger, but short - lived upper crustal magma chambers. Contrib. Mineral. Petrol. 149, 556-575. [4] Abouchami et al. (2005) Nature 434, 851–856. [5] Weis et al. (2011) Nature Geoscience 4, 831-838.

Mineralogical Magazine | www.minersoc.org 2233 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Origin, mobility, and temporal The Itaju do Colônia Sodalite evolution of arsenic from a low- Litchfieldite Stock, NE Brazil 1* 1 contaminated catchment in Alpine ADJANINE CARVALHO S. PIMENTA , HERBET CONCEIÇÃO , 1 2 MARIA LOURDES SILVA ROSA , ROBERT F. MARTIN , crystalline rocks 3 DÉBORA CORREIA RIOS 1,2 3 4 ERIC PILI , DELPHINE TISSERAND *, CORINNE CASIOT , AND 1 3 Sergipe Federal University, Núcleo de Geologia, Aracaju, Brazil, SARAH BUREAU [email protected] 1CEA, DAM, DIF, Arpajon, France, [email protected] 2MacGill University, Eath and Planetary Sciences, Montreal, Canada, 2Institut de Physique du Globe de Paris, UMR 7451, Sorbonne Paris [email protected] Cité, Paris, France, [email protected] 3Bahia Federal University, Instituto de Geociências, Salvador, Brazil, 3Institut des Sciences de la Terre (ISTerre), Grenoble, France, [email protected] [email protected] (*presenting author), [email protected] General Aspects 4Laboratoire Hydrosciences, Montpellier, France, The Itaju do Colônia sodalite litchfieldite stock is located in the [email protected] South Bahia Alkaline Province (SBAP) in the São Francisco Craton, NE Brazil. It is an approximatelly 3 km2 ellipsoidal intrusive body that cuts the Archean–Paleoproterozoic granulitic basement of the Introduction Itabuna Belt. SBAP is the unique Brazilian source of the blue The reduction of the limit for As concentration in drinking water sodalitites, and Itaju do Colônia is the most important of them.

from 50 to 10 μg/l led many resource manager to deal with expensive treatments. In the case of arsenic levels around the limit, knowing its Lithogeochemical and Isotopic Data origin and temporal evolution is of great importance. Here, a study The crystallization age for these rocks is 732 ± 8 Ma (U–Pb case from an alpine basin is presented. titanite). Diverse types of syenites with variable amounts of blue Results sodalite constitute this massif. The contacts between syenites and Arsenic speciation, isotopic compositions of pyrites, sulfate and granulitic rocks are sharp, and dykes and pegmatites of syenitic water, and major and trace element concentrations indicate a composition are common in those areas. In the Eastern area, a layer geogenic source of arsenic due to the dissolution of pyrite. New tools of massive blue sodalite (sodalitite) 6-8 m wide occurs. Nearby, the 34 are provided to study As in water: δ SSO4 and [As] are negatively transition between sodalite–nepheline syenites and granulites show 18 V III correlated, δ OSO4 and [As ]/[As ] are correlated. A monthly interrelated metric apophises of calcite, phlogopitite and monitoring of [As] in some springs started in 2005 and shows an carbonatite, in which xenoliths of blue sodalite are common. Flux increase of [As] compared with scattered data from 1998-2002. A 3- structures and contact relationship suggest the coexistence of three year monitoring at high resolution demonstrated that drought (3) distinct magmas, that seem to be coeval in this stock: (i) Cl-rich conditions enhance pyrite dissolution. The 2003 summer heat wawe phonolitic, (ii) thomsonite-bearing carbonatitic, and (iii) ultrafemic- had a major effect. The increase in [As] between years 1998-2002 ultrapotassic (calcite phlogopititic). The blue syenites show a wide and 2005-2011 may result from the effects of droughts. range of textures and sodalite contents. They consist of sodalite, perthitic alkali feldspar, aegirine, nepheline, albite, cancrinite, annite and paragonite; the accessory minerals include calcite, zircon, titanite, apatite, and magnetite. Late fractures are filled with white minerals identified by X-ray diffractometry as natrolite, ferrihydrite, manganosite, halite, gonnardite, halloysite and “chloromagnesite”. Lithogeochemical data show that these syenites are strongly

fractionated (53 < SiO2 < 61), have high contents of alkalis (14 <

Na2O+K2O < 20); 1.5 < Na2O/K2O < 4.2; and 19 < Al2O3 < 25. These are peralkaline rocks with elevated amounts of chloride (Cl up Figure 1 : Arsenic concentrations correlate negatively with δ34S of to 3%), Zr (up to 20,000 ppm), Nb (up to 160 ppm), Y (up to 70 dissolved sulfates. Larger As mobilization is linked with larger S- ppm), Th (up to 50 ppm) and Pb (up to 18 ppm). The REE patterns isotope fractionation resulting from larger pyrite dissolution. are flat, 10 to 100 times richer than chondrites, and show a strong negative anomaly in Eu.

Conclusions Concluding Remarks V 2- As is the major arsenic species in the form HAsO4 but As The new data show that the crystallization of the Itaju do originates in a more reducing environment than measured. The Colônia syenites resulted from a magmatic system in which Cl-rich increase of fractionation factors leads to a negative correlation phonolitic, carbonatitic and ultrafemic-ultrapotassic magmas have 34 between δ SSO4 versus [As] and oxygen isotopes show that pyrite developed late and bear complex relationships. Acknowledgments: dissolution appears in anaerobic conditions.Temporal evolution This work was supported by CNPq, CBPM and FAPITEC. shows that pyrite dissolution is enhanced by droughts.

Mineralogical Magazine | www.minersoc.org 2234 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Epitaxy of calcite on dolomite and Next generation of in situ chemical kutnahorite (104) surfaces analysis of Titan aerosols via laser 1* 1 CARLOS M. PINA , CARLOS PIMENTEL , AND ENRICO desorption mass spectrometry 2 GNECCO , VERONICA PINNICK1,2*, JOSHUA SEBREE1, XIANG LI1,2, 1 1 1 Departamento de Cristalografía y Mineralogía, Universidad MELISSA TRAINER , WILLIAM BRINCKERHOFF , PAUL 1 Complutense de Madrid, Spain, [email protected]; MAHAFFY [email protected]. (* presenting author) 1NASA Goddard Space Flight Center, Greenbelt, MD, USA, 2 IMDEA Nanociencia, Madrid, Spain, [email protected]. [email protected]*

2University of Maryland, Baltimore County, Baltimore, MD, USA

Carbonate minerals with dolomite-type structure show an Laser desorption mass spectrometry is an attractive analytical anomalous reactivity in aqueous environments. Two examples of this tool for the search for organics in space flight missions. Laser are the complex dissolution paths of kutnahorite, Mn,Ca(CO3)2, in desorption provides complementary information to that obtained pure water [1] and the growth inhibition of dolomite, Mg,Ca(CO3)2, via the more ubiquitous methods like pyrolysis GC-MS and EGA from supersaturated aqueous solutions at ambient conditions, because it provides molecular information without the need for i.e.“the dolomite problem” [2]. Key to resolving the problems linked sample heating. It is also well suited to space flight missions due to the reactivity of these minerals is the systematic investigation of to the relative ease (or complete lack) of sample preparation. the interaction between their surfaces and aqueous solutions with Many mass analyzers have been used in previous missions, such as various compositions and saturation states [3,4]. time-of-flight and quadrupole mass spectrometers, but ion traps in Here we present Atomic Force Microscopy (AFM) particular have the potential to operate at higher pressures with observations of the epitaxial growth of calcite on dolomite and lower power requirements. One such space flight mission in the kutnahorite (104) faces at room temperature. Growth was promoted development phase is the Mars Organic Molecule Analyzer by immersing freshly cleaved dolomite and kutnahorite crystals into (MOMA), aboard the joint NASA/ESA rover ExoMars set to highly supersaturated aqueous with respect to calcite (20 < βcalcite = launch in 2018. There, Martian soil core samples from a depth of 2+ 2- [a(Ca )·a(CO3 )/Ksp,calcite] < 100). Epitaxial growth of calcite ~2 meters will be interrogated by either pyrolysis gas occurs by both the spreading of thin layers and the nucleation and chromatography or laser desorption mass spectrometry in ambient growth of oriented three-dimensional islands on (104) substrates. atmospheric conditions. The mass analyzer is a linear ion trap, While the growth of calcite thin films is highly anisotropic, the capable of providing chemical structural analysis via tandem mass nucleation of 3D-islands occurs preferentially on step edges. This spectrometry (MS/MS). A similar mass spectrometer can also be indicates relatively large substrate-overgrowth interfacial energies. used for analysis of atmospheric particulates, if collected or Moreover, sequences of AFM images of 3D-islands show that spiral concentrated properly. Potential applications could include the growth on simple or multiple screw dislocations is frequent. The analysis of Titan's atmospheric components or deposited organic presence of such dislocations can be related to the accommodation material on the surface. of lattice-misfit strains as epitaxial growth proceeds. Additional To better understand the instrumental response to Titan-like information provided by recording lateral (friction) forces during aerosols, a series of aerosol analogs have been generated via far- the scan with increasing loading forces indicates low adhesion UV irradiation of relevant Titan precursors. Aerosols are collected forces between 3D-islands and (104) substrates. and deposited onto a sample plate interfaced to a commercial Our AFM observations show that the epitaxial growth of calcite version of the MOMA instrument (Thermo MALDI LTQXL). By on dolomite and kutnahorite (104) surfaces is a complex exploring different aerosol precursors, we are able to test phenomenon that leads to the formation of surface patterns at the sensitivity of the instrument to different chemical characteristics of nanometric scale. The development of such patterns is discussed the aerosol, including pure hydrocarbons, nitrogen-containing considering the factors that control the epitaxial growth modes, i.e. compounds, and large aromatic structures. We will present mass Frank-Van der Merwe, Volmer-Weber and Stranski-Krastanov [5]. spectrometric results for the range of synthesized analog aerosols; for example, we will compare the spectra of benzene-sourced [1] Mucci (2004) Aquatic Geochemistry 10, 139-169. [2] Lippmann aerosol to those sourced from the nitrogen-heteroatom equivalent (1973) Sedimentary carbonate minerals, Springer-Verlag, 228 pp pyridine. These results will highlight the compatibilty of the laser [3] Hu, Grossie & Higgins (2005) American Mineralogist, 90, 963- 968. [4] Higgins & Hu (2005) Geochimica et Cosmochimica Acta, desorption method to give abundant molecular and fragment ions 69, 2085-2094. [5] Chernov (1984) Modern Crystallography III, for these classes of compounds. Further, the results from the Springer-Verlag, 517 pp. commercial instrument will be compared to analyses utilizing the prototype MOMA instrument, currently in development.

Mineralogical Magazine | www.minersoc.org 2235 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Discriminating magmatic sources from The nearly-primary magmas at the Phlegraean Volcanic District (Italy): fractionation processes using N, Ar and new insights by the isotope and trace Pb: the Monteregian Hills alkaline element whole-rock and in-situ melt province inclusion geochemistry 1 2 PIOCHI MONICA *, DE ASTIS GIANFILIPPO , MORMONE 1* 2 1 3 4 DANIELE L. PINTI , EMILIE ROULLEAU , ROSS K. ANGELA , MORETTI ROBERTO , ZANETTI ALBERTO 3 4 5 STEVENSON , NAOTO TAKAHATA , YUJI SANO 1Istituto Nazionale di Geofisica e Vulcanologia, sezione Osservatorio

1 Vesuviano, Napoli, Italy , [email protected] GEOTOP, Montréal, QC, Canada 2 [email protected] (* presenting author) Istituto Nazionale di Geofisica e Vulcanologia, Roma, Italy , 2 The University of Tokyo, AORI, Kashiwa, Japan [email protected] [email protected] 3Dipartimento di Ingegneria Civile, Seconda Università degli Studi di 3 GEOTOP, Montréal, QC, Canada Napoli, Aversa, Italy, [email protected] [email protected] 4Isituto di Geoscienze e Georisorse, Consiglio Nazionale delle 4 The University of Tokyo, AORI, Kashiwa, Japan Ricerche, Pavia, Italy, [email protected] [email protected] 5 The University of Tokyo, AORI, Kashiwa, Japan [email protected] The Phlegraean Volcanic District in Italy, including Procida and Ischia islands and the Campi Flegrei caldera, homes to recent N, He, Ar and Pb isotopic compositions were measured in volcanism, impressive geothermal system and high volcanic risk. pyroxenes and amphiboles from Monteregian Hills (Québec, Here, as well along the eastern Tyrrhenian Sea edge, the role of Canada) rocks in order to constrain the mantle sources that genesis and evolution on magma compositions is continuously originated this alkaline igneous province, a controversial issue lasted debated because of the lack of mantle-derived xenoliths, the paucity for more than 30 years. Most common hypothesis is that of primary rock compositions and the large variability of isotope rock Monteregian Hills formed by the passage of the North-American craton over the Great Meteor hotspot [1]. However, melting of geochemistry. The debate also extends to the significance of high- subcontinental mantle and magma rising through faulting related to temperature fumaroles, the origin of which is directly attributed to a the Cretaceous North-Atlantic opening has been also advocated [2]. deep source, as to the mystery of its geochemical features beneath the Noble gases and N were extracted by crushing. Measured He, Ar Campania. We focus on the least evolved shoshonite that belongs to and N isotopic and elemental compositions are partially fractioned the sole Procida and defines a roughly common whole-rock chemical by magma degassing and fluid-rock interactions during magma trend with the Campi Flegrei products. The new data concerns with: ascent. In contrast, 40Ar/ 36Ar ratios are not fractionated, but diluted 1) O isotopes for whole-rocks and mineral phases; 2) mineral and by an atmospheric/crustal source. An observed correlation between the 40Ar/ 36Ar and 208Pb/206Pb ratios suggests two-component mixing. glass in-situ major oxide geochemistry by Electron Microprobe; 3) in- The first component may be related to a plume source with high situ trace element geochemistry on olivine-hosted melt inclusions and 208Pb/206Pb ratios (≤ 2.06) and moderate 40Ar/ 36Ar ratios (~ 1,200) glassy matrix by Laser Ablation Inductively Coupled Plasma Mass 40 36 that are less than the values of depleted mantle ( Ar/ Ar =35,000). Spectrometry and 4) in-situ halogen and B isotope in the olivine- 208 206 The second component shows lower Pb/ Pb ratios (≤ 1.95) and hosted melt inclusions by Secondary Ion Mass Spectometry. These 40 36 near-atmospheric Ar/ Ar ratios (~ 300) and could be related to a new data on glass and mineral have incremented the diagnostic power recycled source such as HIMU. 36 of the available information on the geochemistry and isotope Sr, Nd, Although measured N2/ Ar ratios are diluted by an atmospheric-like source, they show an inverse correlation with Pb, B, O and He-systematics of the Phlegraean whole-rocks, 206Pb/204Pb. This correlation is interpreted as the mixing between a supporting the idea that the Procida magmas are the primitive end- recycled component (HIMU) and an ambiguous mantle source that member for the Campi Flegrei caldera volcanism. The G18O values are could be either a plume source or the depleted mantle. Indeed, the <5.88%o for the Procida samples, wherea the highest values 15 non-fractionated G N values for this mantle source are close to - (>7.79%o) characterize the Campi Flegrei samples. The lowest G18O 8‰, which favors a depleted mantle source similar to that feeding 87 86 15 is associated with low Sr/ Sr (≥0.70561), high Mg#, Cr, Ni and N-MORBs (G N = -5±2‰). Consequently, a part of the volatile 3 4 He/ He (≤4.76-5.47Ra) values and Fo-richer olivines; instead, the budget might have a depleted mantle isotopic signature. This study shows the great potential of coupling radiogenic isotopes together heavy Sr and He isotopes always increase in the Campi Flegrei rocks. 143 144 11 with Ar and N isotopes. Nitrogen and argon are efficiently recycled Procida also shows Nd/ Nd≤0.512553 and δ B=-3÷-8%o, higher in the mantle and thus can be helpful in discriminating the crustal and with respect to the Campi Flegrei. REE produce fractionated patterns mantle sources in oceanic and continental volcanism. with Eu negative anomalies that are absent in the Procida melt inclusions and variously developed in the most evolved Phlegrean [1] Sleep N. (1990). J. Geophys. Res 95, 21983-21990. [2] glassy matrix and whole-rock. Trace elements are typically enriched McHone, G.J. (1996) Canadian Mineralogist 34, 325-334. with respect to the Enriched MORB composition, with positive spikes for Pb. Interestedly, analyzed Procida melt inclusions mime the OIB composition, although showing very high Cs and Pb and moderate Rb, Ba, Th and U enrichments, as well as Nb and Ti depletions. The detected variation appears correlated to crystallization depth of mineral phases suggesting the main role of evolutionary processes within the crust at the Campi Flegrei caldera.

Mineralogical Magazine | www.minersoc.org 2236 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts From many thousand tons to the The Upper Pennsylvanian laboratory balance pan Hushpuckney Black Shale Member from the Swope Formation in Francis F. Pitard 1 Kansas: Rhenium – Osmium 1. Francis Pitard Sampling Consultants, LLC, Broomfield, Colorado, USA. [email protected] Isotope Systematics, and the Highly Siderophile Elements. ABSTRACT We could define an unshakable optimist as someone who sincerely 1* 1 LYNNETTE L. PITCHER , E. TROY RASBURY , RICHARD J. believes that the analysis of a few milligrams by micro-XRF, ICP- 2 3 MS, or other sophisticated techniques may be representative of a WALKER , W. LYNN WATNEY

several-thousand-ton ore block in a mountain or of a full shipment 1 of any commodity traveling around the world. The many steps Stony Brook University, Stony Brook, USA (*presenting author: [email protected], [email protected]) involved between the many orders of magnitude in weight changes 2 are often dismissed as the steps that will totally ruin the analyst University of Maryland, College Park, USA [email protected] 3Kansas Geological Survey, Lawrence, USA [email protected] efforts. The assumption that the final analytical subsample is

representative of the bulk from which it originated is an audacious The Pennsylvanian Hushpuckney “core” black shale of the one and extreme precautions involving theory and practice must be Midcontinent USA has been well studied geochemically and taken. Unfortunately, many important steps are too often casually stratigraphically, but lacks Re, Os, and other HSE (Ir, Ru, Pt, and addressed at best and the ultimate fault is too often attributed to Pd) data. We studied eleven samples from interpreted anoxic and the incompetence of the analyst, disregarding causes arising out of euxinic intervals of four cores and found highly uniform chondrite- improper sampling and subsampling. Furthermore, at the normalized HSE patterns. The concentrations are as follows: Os laboratory, the most probable assay result is not independent of the (0.27-9.8), Ir (0.02-0.07), Ru (0.04-0.31), Pt (3.0-11.3), Pd (0.32- weight of the selected subsample analyzed. Case histories are 13.3), and Re (34.6–1,827), in parts per billion. The Re-Os data summarized. Solutions borrowed from the well-established Theory show significant scatter on a 187Re/188Os versus 187Os/188Os of Sampling are suggested. Appropriate sampling and subsampling isochron plot but give the expected early Kasimovian (Missourian) diagrams providing good visual indicators are recommended. age of 306 Ma. The HSEs and Mo were used to consider Precautions for the development of Standard Reference Materials geological processes that might have influenced the Re-Os are also listed. systematics, and caused the extraordinary spread in 187Re/188Os (713-9122). Chondrite-normalized HSE patterns are similar to that of seawater, but with slightly higher relative Re and slightly lower relative Os, consistent with the interpretation that the Midcontinent Seaway had a fairly unrestricted opening to the global ocean. Rhenium and Mo show a positive correlation that suggests sulfidic conditions were, in part, responsible for Re enrichment. It has been suggested that high Re concentrations from late Permian black shales reflect the unusual conditions during that interval, including warming deep water temperatures and increasing ocean acidity, which were linked to the deterioration of environmental conditions at the end of the Permian[1]. The Re concentrations and 187Re/188Os from the Hushpuckney black shale are higher than any reported from the late Permian, suggesting environmental deterioration is not the only reason for late Permian Re enrichment (Fig.1). More data from across the interval that represents the time of unification of Pangea (Early Carboniferous to Late Permian) may offer further insight into processes that control availability of HSE in black shales.

Figure 1: Compilation of Re-Os data [1] with Hushpuckney data shown for comparison.

[1] S. Georgiev et al. (2011) EPSL 310, 389-400.

Mineralogical Magazine | www.minersoc.org 2237 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Natural organic matter roles in Significance of sulfidic floc/sediment Pb dynamics organic-rich Archean shales

1 2 1* 1 NOAH J. PLANAVSKY , CLINTON T. SCOTT , CHRIS JANINA PLACH AND LESLEY WARREN 1 2 1 REINHARD , BOSWELL WING , TIMOTHY W. LYONS 1McMaster University, School of Geography and Earth Sciences, 1Univerrsity of California, Riverside, U.S.A., [email protected] (* presenting author) [email protected], [email protected], [email protected] [email protected] 2 McGill University, Montreal, Canada, [email protected], Introduction [email protected] Natural organic matter (NOM) is a fundamental component of

freshwater ecosystems and a geochemically significant substrate for lead (Pb) transport, retention and fate in watersheds. Although Pb release into the environment by atmospheric deposition has declined In the past few years multi-proxy studies of black shales have in recent decades, concern remains whether Pb remobilization from transformed our view of the evolution of Precambrian Earth system sediments (e.g. pH driven Pb solid-solution partitioning) and processes1-4. Part of the utility of black shale studies lies with our subsequent transport by soluble organic-Pb complexes and floc- ability to tie them to well-understood modern and Phanerozoic aggregates may continue to pose risk to freshwater ecosystems. As such, the objectives of this study were to: (1) investigate Pb and analogs. Geochemical signatures in black shales have the potential to NOM distributions among suspended floc, surficial bed sediment hold information about concentrations of key trace nutrients, the and water-column compartments; (2) identify the important solid emergence of an oxidative biosphere, and the onset of significant phases for Pb sequestration in floc and surfical bed sediments; and oxidative weathering. However, there have been relatively few truly (3) establish the role of pH (pH 5-8) impacting dissolved organic comprehensive, multi-proxy studies of Precambrian units, which has carbon (DOC) and Pb solid-solution partitioning from natural made it difficult to delineate temporal trends from the black shale limnetic floc, as well as lake, stream and wetland sediments both in record and to evaluate the significance of emerging geochemical situ and under controlled laboratory settings. Results and Conclusions results. This problem is particularly acute for the Archean. To fill Water, floc and sediments were collected for aqueous Pb and this gap, we have conducted a multielement (C-S-Fe-trace metal) NOM analysis across nine highly variable freshwater (wetland, biogeochemical study in black shales from several (ca. 2.7 Ga) drill stream, lake) ecosystems of Ontario, Canada. Results indicate cores within the Abitibi Greenstone belt in Ontario. We are soluble organic-Pb complexes dominated Pb aqueous species in particularly interested in the Abitibi since it was a strongly NOM-rich environments. Surficial sediments and floc showed hydrothermally influenced basin. distinct Pb sequestration and solid-solution partitioning patterns

across sites driven by differential roles of living versus refractory NOM within each compartment. Stable organo-Pb complexes The shales are marked by variable but in some cases extremely dominated sediment Pb solid-solution partitioning, as mobilization high organic carbon concentrations (up to 32% TOC). C-S-Fe of DOC and Pb occurred with increasing pH from NOM-rich systematics and simple sediment dilution calculations suggest that sediments, while Pb release was inhibited from NOM-poor oxygenic photosynthesis was the primary source of organic carbon sediment. In contrast, amorphous Fe oxyhydroxides, collected by in the basin. Further, our data reveal a sustained and spatially microbes and extracellular polymeric substances, were the best widespread episode of Fe-limited pyrite formation under an anoxic predictor of floc Pb solid-solution partitioning and the key floc Pb water column. The Abitibi work, therefore, supports the emerging sequestration phase across sites. These results and their implications for Pb mobility in freshwater catchments from upstream NOM-rich view that euxinic conditions where a common feature in productive wetlands through to downstream NOM-poor littoral lake Archean settings. Trace metal systematics allow us to tease apart the environments will be presented. influence of hydrothermal systems on abundances of bio-essential metals in Archean anoxic oceans. We will foucus on Mo, Zn, Cu, and U systematics and co-variation.

[1] Anbar et al. (2007) Science, 317, 1903-1906 [2] Scott et al. (2008) Nature, 452, 456-459 [3] Reinhard et al. (2009) Science, 326, 713-716 [4] Scott et al. (2011) Geology, 39, 119-122.

Mineralogical Magazine | www.minersoc.org 2238 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Water loss from melt inclusions in Characterisation of the Cr isotopic pyroclasts of differing sizes signature of marine sediments 1* 1 1 TERRY PLANK , ALEX LLOYD , PHILIPP RUPRECHT , ERIK deposited in the S1 Mediterranean 2 3 HAURI , WILLIAM ROSE sapropel 1Lamont Doherty Earth Observatory, Columbia Univ., Palisades, NY, HELENE PLANQUETTE 1*, RACHAEL H. JAMES 1, IAN J. USA, [email protected] (* presenting author) PARKINSON2 2 Carnegie Instit. of Washington, DC, USA, [email protected] 3Michigan Tech Univ, Houghton, MI, USA, [email protected] 1National Oceanography Centre, European Way, Southampton, SO14 3ZH, United Kingdom 2 Our understanding of the pre-eruptive H2O contents of parental Department of Environment, Earth and Ecosystems, CEPSAR, The magmas has come to rely on the measurement of olivine-hosted Open University, Walton Hall, Milton Keynes, MK7 6AA, melt inclusions, and yet there is increasing recognition of the United Kingdom potential short-comings of olivine as a perfect container of *Presenting and corresponding author; [email protected] undegassed melt. Several laboratory experiments have now

demonstrated how melt inclusions can lose or gain H2O through host olivine on short timescales (hours to days), relevant to eruptive The record of past changes in the dissolved oxygen concentration processes. Here we have designed an experiment using natural tephra of seawater is crucial for understanding past climate changes, and for samples that cooled at different rates: ash (≤ 1 mm diam.), lapilli (2 predicting future climate scenarios. Initial measurements of cm), and bomb (6-7 cm) samples that were deposited on the same chromium (Cr) stable-isotope fractionation showed the potential of day (10/17/74) of the sub-plinian eruption of Volcán de Fuego in Cr as a tracer of dissolved oxygen concentrations in groundwaters Guatemala. Ionprobe, laser ablation-ICPMS and electron probe (Ellis et al., 2002). More recently, analyses of ancient marine analyses of olivine-hosted melt inclusions yield a similar range in carbonates and banded iron formations have revealed large variations 53 major element (50-59% SiO2), trace element (Ba/Zr = 4-6) and in δ Cr values, from -0.28 to 5.00‰, (Bonnand et al., 2011; Frei et olivine compositions (Fo#72-79) in the different clast populations, al., 2009, 2011), which are distinct from the continental crust and that also match the range in the host bulk tephra and groundmass. terrestrial mantle (~-0.12 ‰; Schoenberg et al., 2008) and are Melt inclusions from the ash and lapilli samples record the highest interpreted to reflect past variations in seawater oxygenation.

H2O contents, up to 4.4 wt%. On the other hand, melt inclusions in

the bomb samples indicate up to 30% lower H2O contents (loss of ~ In order to fully assess the validity of this new proxy, the effects

1 wt% H2O), despite similar S, CO2 and K2O concentrations, of post-depositional diagenesis on Cr and Cr isotopes need to be consistent with the longer time available for re-equilibration with quantified. To this end, we will present the results of analyses of Cr degassing magma through the olivine. Inclusions from bombs also isotopes in sediment cores that record the deposition of the most record up to 10% post-entrapment crystallization of olivine, while recent eastern Mediterranean sapropel (S1) between 7 and 10 14C kyrs those from the ash samples record none. Thus, taken at face value, BP. The sapropel has experienced heavy diagenetic alteration which

melt inclusions from small bombs may lose H2O and crystallize is revealed by the presence of maxima in the concentration of many olivine within the 10 minutes maximum that it takes for a 3-4 cm redox-sensitive elements outside of the sapropel layer (Thomson et radius bomb core to cool conductively. This could only occur if the al., 1995). The Cr data will be compared with these other redox- fast redox exchange mechanism for H diffusion in olivine were sensitive elements, and measurements of the Cr isotopic composition operating (D ~ 10-9 to 10-10 m2/s). On the other hand, several lines of seawater samples that have different levels of dissolved oxygen. of evidence point to some of this water loss also occurring pre- These new data will allow us to assess the mobility of Cr during eruptively, during magma ascent and degassing in the conduit. Some diagenesis and the robustness of Cr isotopes as a redox-proxy. of the smallest melt inclusions (< 50 micron diameter) within ash and lapilli appear to have lost up to 10% water, and yet sufficient time is not available during post-eruptive cooling to allow this even [1] Bonnand, P., et al. (2011) J. Anal. Atom. Spectrom., 26, 528-535 [2] Ellis, A.S., et al., (2002). Science, 295, 2060–2062 given the fastest known H diffusivities. Moreover, inclusions [3] Frei R., C. et al., (2011). Earth Planet. Sci. Letters, 312, 114-125. selectively sampled from the outer cm of bomb clasts record greater [4] Schoenberg, S., et al., (2008). Chem. Geol., 249, 294-306 water loss than those in 1 cm radius lapilli, consistent with a longer [5] Thomson J., N.C. et al., (1995). Geochim. Cosmochim. Acta, 59,

timescale for H2O loss for all the bomb magma, and not just the 3487-3501 slowly cooled bomb interiors. Thus, our results point to both slower post-eruptive cooling and slower magma ascent affecting bomb melt

inclusions, leading to H2O loss over the timescale of 10 minutes to hours. The important implication of this study is that a significant

portion of the published data on H2O concentrations in olivine-

hosted melt inclusions may record some H2O loss and not primary water, particularly for samples taken from lavas or bombs, or small inclusions (< 40 microns diameter) in general. Future sampling and analysis should bear these considerations in mind.

Mineralogical Magazine | www.minersoc.org 2239 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts New approaches for the prediction of Impact of biological Mn(II) oxidation contaminated neutral drainage on the fate of subsurface U(IV) 1* 2 1* 2 3 3 BENOÎT PLANTE , BRUNO BUSSIÈRE , AND MOSTAFA K.L. PLATHE , S-W. LEE , Z. WANG , D.E. GIAMMAR , B.M. 3 2 4 1 BENZAAZOUA TEBO , J.R. BARGAR ; R. BERNIER-LATMANI 1Université du Québec en Abitibi-Témiscamingue (UQAT), Institut 1*École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, de Recherche en Mines et Environnement (IRME), [email protected] (* presenting author) [email protected] (* presenting author) 2Orgeon Health & Science University, Portland, OR, USA 2UQAT, IRME, [email protected] 3Washington University in St. Louis, St. Louis, MO, USA 3INSA-Lyon, [email protected] 4Stanford Synchrotron Radiation Lightsource, Menlo Park, CA, USA

Context and objectives Uranium contamination of the subsurface, resulting from Contaminated neutral drainage (CND) is the presence of metal mining and processing of the radionuclide, is a concern in concentrations above regulatory requirements at circumneutral pH numerous locales. The oxidized form of U, hexavalent uranium in mine drainage [1]. The generation of CND by tailings and waste (U(VI)), is soluble and mobile. Therefore, understanding its rocks is a growing concern for the mining industry due to fate and transport is critical for the management of increasingly restrictive regulatory requirements. Difficulties in contaminated environments. U(VI) can be biologically reduced CND prediction arise from the low oxidation rates of sulfide to U(IV) species that are less soluble, such as the mineral minerals and from the metal retention potential within the wastes. uraninite (UO2) or monomeric U(IV). Stimulating biological The latter induces an important delay in the formation of CND activity in the subsurface has emerged as a possible conditions [2]. For now, it is not possible to account for this delay remediation strategy for uranium contamination and would using prediction techniques developed for acid-mine drainage result in the formation of an in situ waste form consisting of (AMD) prediction, such as humidity cells, columns and lysimeters. U(IV). However, the long-term stability of U(IV) in the This presentation aims to present (1) the main differences in AMD subsurface is still poorly understood. In particular, the and CND predictions, and (2) new approaches currently under study formation of biogenic manganese oxides, known to rapidly for CND prediction. oxidize UO2 [1], may significantly impact the persistence of U(IV). This study focuses on probing the occurrence of Mn Overcoming the metal retention prediction challenge oxidation in the subsurface at a U contaminated site (Rifle, CO The main challenge of CND prediction is to quantify the metal USA) and the ultimate fate of U in the system. Agarose gel retention potential of mine wastes, especially when sorption pucks, containing Mn oxidizing spores and reduced U, were phenomena are involved in metal retention [1]. Three approaches are prepared as initial probes of the U/Mn redox system to currently used to overcome this difficulty. Firstly, the sorption determine if U(VI) was released from the gel after oxidation of potential is estimated using batch sorption studies [2, 3]. The second U(IV) by Mn oxides. Initial results indicate extensive Mn approah consists of artificially saturating the sorption potential of oxidation within gels and almost no release of U from the gels the mine waste [4]. This can be done by contact with a contaminated after a month. U was present as U(VI) in the gels and X-ray leachate in sorption-enabling conditions until saturation of the absorption results indicate it may be a sorbed species. To retention potential. These approaches both require that the possible investigate such reactions at the field scale, columns containing metals involved in CND are known prior to the tests, which require sediment previously enriched with reduced U in situ were an exhaustive material characterization. Although they enable the prepared for deployment in the same aquifer’s sub-oxic zone qualitative estimation of the retention potentials of mine wastes, under Mn oxidizing conditions. Initial results from these their results are virtually impossible to scale up from the lab to the experiments indicate U oxidation and release over a two month field. A third approah currently under study is to inhibit metal period. In order to more accurately pinpoint cause and effect sorption at the source using complexing agents. The ideal in this system, laboratory columns were prepared with the complexing agent for this matter would inhibit sorption phenomena same sediment and artificial groundwater. These experiments by chelating the metals generated by sulfide oxidation, therefore will determine the relative contribution of O 2 and Mn(IV) to disabling it from any other geochemical reaction, while it would not U(IV) oxidation. Furthermore, TEM and XAS analysis of interfere with any other geochemical processes involved. both field and lab sediments will determine spatial location of U in relation to Mn. These combined methods will give a Conclusion more detailed view of the interactions between Mn and U in New approaches are currently developped to define the sorption the subsurface. Because bioremedation technology is potential and its impact in the mobilization of metals for CND contingent on the product being stable, this is valuable prediction. These approaches will help in the development of a information which can help evaluate the viability of future CND-specific protocol for the prediction of mine drainage quality. remediation approaches.

[1] Nicholson (2004). MEND Workshop, Sudbury. [2] Plante, [1] Chini (2008) Environ. Sci. Technol. 42, 8709-8714. Benzaazoua & Bussière. (2011) Mine Water Envir 30, 2-21. [3] Plante et al. (2010). Appl Geochem 25, 1200-1233. [4] Plante, Benzaazoua & Bussière (2011). Mine Water Envir 30, 22-37

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* BEN XU, MICHAEL GRUDICH, AND KRISTIN M. PODUSKA deep corals from Orphan Knoll

Memorial University, Department of Physics and Physical Oceanography, ANDRÉ POIRIER*1, SOPHIE RETAILLEAU1, AURÉLIEN BLENET1,2, St. John's (NL), Canada, [email protected] (presenting author) BASSAM GHALEB1, CLAUDE HILLAIRE-MARCEL1, AND EVAN EDINGER2 Assessing local and long-range order in biogenic minerals 1GEOTOP-UQAM, Montréal, Canada, The degree of structural order within biogenic minerals is key for [email protected] (*presenting author) understanding the temporal evolution of mineralization in biological [email protected] systems.[1] Standard material characterization techniques, including [email protected] Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction [email protected] (XRD), are widely used to assess structural differences in biogenic [email protected] magnesium calcites and carbonated hydroxyapatites.[2,3] However, no 2Memorial University, St. John’s, Canada, single measurement tool can adequately assess both local order (as can be [email protected] done with FTIR) as well as long-range periodicity (as can be done with

XRD). In this work, we identify serious pitfalls that can occur when trying to extract details about the structural order in a mineral from broadened spectroscopic or diffraction peaks. We also show that these challenges can be addressed by using relatively simple analyses to track FTIR Baffin Bay seawater espilon Nd signature was measured more spectral changes in amorphous and poorly crystalline materials with than 25 years ago (Stordal and Wasserburg, 1986) at a very low value biogenic, geogenic, or anthropogenic origins. when compared to the average North Atlantic Ocean. This unradiogenic value is introduced into the North Atlantic Ocean Results of diffraction-limited infrared spectroscopic studies through the Labrador current that flows on the East coast of Canada. Comparisons between FTIR transmission spectra from conventional Seawater from all water masses from Baffin Bay and the bench-top instruments and data collected under spatially resolved, Labrador Sea (near Orphan Knoll) were sampled during cruises of diffraction-limited conditions at the Canadian Light Source (Mid-IR CCGS Hudson in 2008 and 2010. Using McLane™ pumping systems beamline) highlight that there are both structural (material-specific) and equipped with Mn-oxide coated cartridges, dissolved neodymium measurement geometry contributions to spectral line widths. These (Nd) was recovered from a200 liters of seawater for many casts. The conclusions are based on auto-correlation analyses[4] applied to spectra geographical area covered allows us to monitor the present day HNd from a series of calcite samples with different particle size distributions. signatures of Baffin Bay overflow water, as well as that of all other Using similar auto-correlation analyses with carbonated hydroxyapatites water masses involved in the Atlantic Meridional Overturning and other biominerals is straightforward, but the interpretation and Circulation (AMOC). implications of the results present new and interesting questions related During the 2010 cruise, the Canadian remotely operated vehicule to structural order at intermediate length scales. In this context, we (ROPOS) was used to sample specimens of deep-water cup corals compare our approach with other common metrics for tracking (alive and fossils) from Orphan Knoll, at a depth of approximately crystallinity, including the infrared splitting factor that is routinely 1700-1800 m below surface, i.e., near the depth-limit of the Present reported for apatitic phosphate biominerals. Labrador Sea Water mass. U-Th data in modern (live-collected) specimens of Desmophyllum dianthus yield critical information on Conclusions the efficiency of the cleaning procedure used, with respect to the 230 We demonstrate that the co-existence of material-specific and removal of oxide coatings ("clean" samples must yield zero Th- measurement-specific contributions to infrared peak broadening can be ages), and thus on the representativity of the Nd isotope data 14 beneficial for extracting information about the differences in structural obtained. The same approach combined with C-ages is used in order that can occur in biogenic, geogenic, and anthropogenic minerals. fossil coral studies, as a means to document, back in time, water mass These effects can be decoupled in FTIR transmission measurements, changes at Orphan Knoll, in relation with the AMOC/climate obtained with standard bench-top instruments, by using a robust auto- variability. correlation analysis of peak widths. An important implication of this result is that infrared spectroscopy has enormous potential as a quantitative tool for tracking changes in the structural order during biomineralization and biomimetic mineralization processes.

[1] Meldrum, Cölfen (2008) Chemical Reviews 108, 4332-4432. [2] Poduska, Regev, Boaretto, Addadi, Weiner, Kronik, Curtarolo (2011) Advanced Materials 23, 550-554. [3] Gueta, Natan, Addadi, Weiner, Refson, Kronik (2007) Angewandte Chemie International Edition 46, [1] Stordal and Wasserburg (1986) Earth and Planetary Science 291-294. [4] Balan, Delattre, Roche, Segalen, Morin, Guillaumet, Letters, vol.77, 259–272. Blanchard, Lazzeri, Brouder, Salje (2011) Physics and Chemistry of Minerals 38, 111-122.

Mineralogical Magazine | www.minersoc.org 2241 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts The geochemical features of the Composition evolution of peridotites garnets from peridotites of of Siberian craton lithosphere roots: Udachnaya pipe (Yakutia) harzdurgite→lherzolite→wehrlite 1 1 LYUDMILA N. POKHILENKO *, VLADIMIR G. MALKOVETS , NIKOLAY P. POKHILENKO*, ALEXEY M. AGASHEV, AND 1 2 ALEXEY M. AGASHEV , AND WILLIAM L. GRIFFIN LYUDMILA N. POKHILENKO 1 V.S.Sobolev Institute of geology and mineralogy SB RAS, VS Sobolev Institute of Geology and Mineralogy SB RAS, Novosibirsk, Russia, [email protected] (*presenting author) [email protected] (*presenting author) 2 GEMOC National Key Centre, Macquarie University, Sydney, Peculiarities of chemical composition and geochemical Australia features of extremely fresh xenolith of unique mantle peridotites from Udacnaya kimberlite pipe were studied. The studied xenoliths Iintroduction were formed at the P-T conditions corresponding to the diamond Study of mantle xenoliths from the kimberlite pipes allows to stability field. A studied collection includes some varieties of get an important information about the origin and transformations of megacrystalline Cr-pyrope harzburgites [1,2], metasomatized the lithosphere substance. The most deep-seated rocks of the depleted peridotites [3]; c) fresh sheared Cr-pyrope lherzolites [4]. lithospheric mantle are deformed peridotites, having the features of Obtained results show that ultra depleted peridotites: Cr-pyrope recrystallization and structures of the flow. These rocks undergo dunites and harzburgites including their diamondiferous varieties significant transformations and enrichment with different were secondary enriched in different scale by two different types of components under the effect of asthenospheric melts penetrating by metasomatic agents. The first of them had a geochemical features the cracks and faults [1]. The most depleted rocks which are not close to those of carbonatitic melts. Increase of Ca in system caused affected by the enrichment processes are supposed to be the a transformation of initial paragenesis ol+en+low-Ca knorringite- megacrystalline dunites [2]. rich Cr-pyrope to ol+Cr-cpx+high-Ca uvarivite-rich pyrope (up to 76% Ca-comp.). This process caused enrichment of initially Methods and samples depleted peridotites in LREE and Ca. The garnets from 5 deformed lherzolites (mineral composition: The second type of metasomatic agent had definitely basanitic olivine, orthopyroxene, clinopyroxene, garnet), and 20 composition, and it caused secondary enrichment of initial ultra megacrystalline harzburgite-dunites (mineral composition: olivine, depleted peridotites by Si, Ti, Al, Fe, Ca, Na, K, incjmpatible and garnet, sometimes chromite, orthopyroxene) from the kimberlite HREE, and obviously this process was synchronous to the kimberlite pipe Udachnaya (Yakutia) were analyzed by the LAM-ICPMS. melt generation. CPX and magnesian ilmenite were a prohibited phases in initial ultra depleted peridotites, and in some the most Results and Conclusion enriched peridotites their amounts are up to 20 and 5 vol.%, The chondrite normalized [3] REE patterns of garnets from correspondingly. deformed lherzolites are mostly characterized by smooth increasing Sheared pyrope peridotites have a multistage character of a of LREE values with gradation in the field of HREE. The distribution composition evolution including: a) initial depletion as a result of curves of REE in garnets of megacrystalline dunites have highly extraction from them melts of high degree of partial melting; b) sinusoidal character. The very big difference in REE values is seen enrichment by agent with high content of incompatible elements that in the width of dunite field. It shows the different degree and time of caused significant increase of La/Yb ratio; c) enrichment by their enrichment. basanitic components synchronous to process of kimberlite The most of distribution curves for garnets of megacrystalline formation [5]. dunites have the peaks at the LREE and MREE showing increased Ce (7 samples), Pr (4 samples), Nd (7 samples), Sm (2 samples) [1] Boyd et al. (1997) Contrib. Mineral. Petrol. 128, 228-246. [2] concentrations proving early enrichment. The sharp sinusoidality of Pokhilenko et al. (1993) Russian J. Geol. Geophys. 34, 56-67. [3] REE distribution curves, early enrichment with the LREE prove that Pokhilenko et al. (1999) Proc. 7th IKC, 2, 689-698. [4] Agashev et some garnets of studied dunites were not in the equilibrium with the al.(2006) Doklady Earth Sciences, 407A, 3, 491-494. [5] melt. In general these garnets could be formed as a result of Pokhilenko (2009) Lithos, 112S, 934-941. transformation of earlier chromites [4], which is confirmed by the increased Cr-concentration in them (for example, garnet UV167/09

contains 11.84 wt.% Cr2O3), either as a result of exsolution of primary Al, Cr-containing orthopyroxene, presenting in garzburgites.

[1] Agashev et al.(2010) Dokl. RAN. 432, 510-513. [2] Pokhilenko et al.(1993) Geol. and Geoph. 34/1, 71-84. [3] McDonough & Sun (1995) Chem.Geol. 120, 223-253. [4] Malkovets et al. (2007) Geology 35, 339-342.

Mineralogical Magazine | www.minersoc.org 2242 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Mesoarchean hydrous upper mantle: Sorption and incorporation of radio- Evidence from the Fiskenæsset nuclides at mineral surfaces studied Complex, SW Greenland with quantum chemical methods

ALI POLAT R. POLLY*, B. SCHIMMELPFENNIG, M. FLÖRSHEIMER, F. Department of Earth and Environmental Sciences, University of HEBERLING, T. STUMPF, R. KLENZE, H. GECKEIS Windsor, Windsor, ON, CANADA, [email protected] Karlsruher Institut für Technologie (KIT), Campus Nord, Institut für nukleare Entsorgung (INE), Postfach 3640, 76021 Karlsruhe, The Fiskenæsset Complex, SW Greenland, contains the world’s best Germany (email: [email protected]) preserved Archean (~2970 Ma) layered anorthosite, leucogabbro, gabbro, and ultramafic rock association. The ultramafic rocks The reliable long-term prediction of actinide migration in consist mainly of olivine-pyroxene hornblendites, peridotites, geological formations requires understanding of the dunites, and pyroxenites. The complex appears to have been adsorption/desorption and incorporation mechanism at the emplaced into Archean oceanic crust (now amphibolite) and later molecular level. The sorption and incorporation of metal ions at intruded by tonalites, trondhjemites and granodiorites (TTGs). The mineral surfaces is a very important process which leads to the complex and bordering TTG intrusions and mafic volcanic rocks retention/retardation of radionuclides such as actinide ions and were variably affected by granulite facies metamorphism and fission products. retrogressed under amphibolite facies conditions. Despite poly- We present three different investigations in this talk: (1) the phase deformation and amphibolite to granulite facies interaction of trivalent lanthanides and actinides with the solvated metamorphism, primary igneous structures and intrusive corundum (110) surface, (2) interaction of selenite with the relationships are well preserved in many outcrops in the complex [1- hydrated calcite surface and (3) the incorporation of trivalent 3]. The Fiskenæsset ultramafic rocks share many petrographic lanthanides and actinides in calcite. Study (1) is carried out with characteristics of unmetamorphosed mafic to ultramafic layered orbital based ab inito and DFT methods using TURBOMOLE, intrusions and Alaskan-type ultramafic complexes. In ultramafic whereas (2) and (3) with plane-wave DFT, as implemented in the rocks, many orthopyroxene grains occur between amphibole and Vienna Ab initio Simulation Package (VASP). olivine grains and contain an intergrowth of symplectitic The corundum (110) surface is a challenging task for a (vermicular) magnetite. These orthopyroxene-magnetite theoretical investigation because singly, doubly and triply intergrowths appear to have grown at the expense of olivine. The coordinated aluminol groups are present simultanously. We used the

origin of the orthopyroxene-magnetite symplectitic intergrowths is Al 27O75H67 cluster in this study as a model system for the corundum attributed to chemical reactions between residual, hydrous, (110) surface. In a first step, we determined the structure and hornblende-forming melts and olivine. In several locations, the deprotonation properties of this cluster and calculated the Fiskenæsset ultramafic sills were intruded by a network of 5 to 40- vibrational frequencies of the surface aluminol groups. These results cm-thick hornblendite veins. Given that horblendites and are compared with experimental data to validate our cluster model. hornblende-bearing gabbros and peridotites are mainly restricted to In a second step we determined the structure of the inner-sphere Phanerozoic supra-subduction zone ophiolites and magmatic arcs, it complexes of the trivalent lanthanides and actinides at the surface. is suggested that the Fiskenæsset Complex represents a relic Various multidentate surface bound inner-sphere complexes are fragment of a Mesoarchean oceanic island arc. The trace element found to predominate. They are characterized and compared with systematics of the Fiskenæsset layered rocks and spatially and experimental results. temporarily associated basaltic amphibolites and TTGs also indicate Se-79 is a fission product of U-235 with a long radioactive half 6 2- 2- that these rock suites originated in an oceanic island arc setting. life of 1.1x10 years. Selenite (SeO3 ) and selenate (SeO4 ) Petrographic observations and geochemical data provide strong interact only weakly with common mineral surfaces. Therefore they evidence for a hydrous sub-arc mantle source for the igneous have been identified as crucial radio nuclides for long term safety Fiskenæsset layered intrusion. Amphibole (mostly hornblende) assessments of nuclear waste disposal. We determined the structure occurs as an interstitial mineral to olivine, pyroxene, plagioclase, of the water/calcit interface and identified surface sorbed and chromite and chrome-spinel and as inclusions in these minerals in incorporated selenite species at the calcite/solution interface. the cumulates, consistent with an igneous origin. It is suggested that The last point tackles the incorporation of trivalent lanthanides water was recycled to the source of the Fiskenæsset rocks through and actinides into calcite. Earlier spectroscopic investigations subduction of altered oceanic crust. Recycling of water to the upper suggest incorporation of lanthanide/actinide ions occupying Ca-sites mantle not only resulted in the generation of igneous amphibole in in the calcite lattice. Charge compensation is achieved by the the complex, but it may also have contributed to the generation of substiution of two Ca atoms by one trivalent lanthanide/actinide and neighbouring TTG-dominant continental crust by Archean one Na ion. Here, we studied modifications of the calcite structure subduction processes. induced by the substitution.

[1] Polat et al. (2009) Precambrian Research 175, 87-115. [2] Polat et al. (2010) Chemical Geology 277, 1-20. [3] Polat et al. (2011) Lithos 123, 50-72.

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Benthic O2 fluxes measured by Eddy Theoretical carbon isotope Covariance in a large flume facility fractionation under deep-earth 1,2,3* 1 1 PIERRE POLSENAERE , CECILE CATHALOT , TOM COX , conditions 1,2 3 3 FILIP MEYSMAN , OLIVIER MAIRE AND BRUNO DEFLANDRE 1* 2 VENIAMIN B. POLYAKOV AND JUSKE HORITA 1NIOZ Yerseke, Ecosystem Studies 1Institute of Experimental Mineralogy, Russian Academy of [email protected] (*presenting author) Science, Russia, [email protected] (* presenting author) [email protected] 2Department of Geosciences, Texas Tech University, Lubbock, TX, [email protected] [email protected] [email protected] 2 Vrije Universiteit Brussel, Analytical and Environmental Chemistry Introduction 3University Bordeaux 1, Environnements et Paléoenvironnements In addition to the major component of mantle carbon, which has δ13C Océaniques et Continentaux values of about -5±3‰, some reduced (carbide, hydrocarbons) and [email protected] neutral (diamond, graphite, dissolved C) carbon compounds from [email protected] 13 mantle xenoliths and other sources have δ C values in the range of - The Eddy Covariance: a new technique to assess 20 to -35‰. Contamination of organic carbons near the Earth sediment-water O2 exchanges over various environments surface and the recycling of sedimentary organic matter via The Eddy Covariance (EC) is a novel technique used to quantify subduction zones have often been invoked to explain the depleted 13 the sedimentary O2 consumption of marine ecosystems [1]. It C signatures of these mantle rocks. However an increasing number measures O2 exchanges at the sediment-water interface over large of studies do not support this scenario. Two other possibilities exist. 2 spatial scales (> 100 m ) without being intrusive or disturbance of First, mantle carbon could have been isotopically heterogeneous the flow field. This new technique has recently been used in various since the accretion from the solar nebula and the core–mantle natural environments as tropical lagoon [2], tidal flat [3], river [4] segregation in the first 100 My of Earth history. Chondrites, and deep ocean [5] systems. carbonaceous chondrites particularly, which are widely considered In autumn 2011, EC deployments were carried out in a 18 m long flume tank (NIOZ Yerseke, The Netherlands) filled with muddy to represent primitive undifferentiated materials from which the 13 sediment (Figure 1). Based on simultaneous measurements of near- Earth accreted, have δ C values ranging widely from -28 to 0‰.

sediment velocities (ADV Vector, Nortek) and O2 concentrations Another possibility is that there exist some mechanisms and

(Unisense Clark-type microelectrode) at high frequency (64 Hz), O2 processes for large carbon isotope fractionation at high exchanges at the sediment-water interface were calculated by EC. temperatures and pressures. For example, Craig [1] and Deines and These EC fluxes were then compared with values based on Wickman [2] reported ca. 12 ‰ differences between graphite and microsensor profiling and chamber incubation. cohenite, (Fe, Ni, Co)3C, from iron meteorites. A recent experimental study by Satish-Kumar et al. [3] reported 2.7 - 4.5 ‰

differences between graphite/diamond and FeC melt at 1350 -

2100°C and 5 - 10 GPa.

Theoretical study Here, we report our updated reuslts of theoreitcal calcualtions on 13 12 C/ C fractionation among major C-bearing materials (CO2, Figure 1: The flume Eddy Covariance deployment (Sept. 2011) calcite, diamond, graphite, and SiC). Our results show that SiC is showing sensor set-up (velocimeter, left and microelectrode, right). depleted in 13C realtive to diamond/graphite and calcite even at very high temperautes: 2.5 - 9 ‰ at 1000 - 2000°C. Our results for SiC First results and conclusions is consistent with the experimental results for FeC melt [3]. High EC O2 fluxes were similar or greater than those obtained by preussures (>10’s of GPa) under deep-Earth conditions may also incubation and microsensor profiling, i.e -23.8˜-62.9, -42.2˜-56.0 affect measurably equilibrium isotope fractionation of C-bearing and -15.8˜-19.5 mmol m-2 d-1 respectively. EC fluxes varied with species [4]. Thus, the recent experimental study and our theoretical flow velocity, sensor depth and upstream location. The deployment calculaitions clealry demonstate that carbides (Fe C and SiC) are of the EC technique in the flume facility allows to investigate 3 significatnly depleted in 13C at high tmeperatues and pressures. We various aspects of boundary layer hydrodynamics under controlled conditions. need to revise and improve our understanding of carbon cycles and associatted isotope fractionation in the deep-Earth. [1] Berg et al. (2003) Mar. Ecol. Pro. Ser. 261, 75-83. [2] Hume et al. (2011) Limnol. Oceanogr. 56, 86-96. [3] Kuwae et al. (2006) [1] Craig (1953) GCA 3, 53-92. Mar. Ecol. Pro. Ser. 307, 59-68. [4] McGinnis et al. (2008) [2] Deines and Wickman (1975) GCA 39, 547-557 Geophys. Res. Lett. 35, doi:10.1029/2007GL032747. [5] Berg et al. [3] Satish-Kumar et al. (2011) EPSL 310, 340-348. (2009) Limnol. Oceanogr. Meth. 7, 576-584. [4] Polyakov & Kharlashina (1994) GCA 58, 4739-4750.

Mineralogical Magazine | www.minersoc.org 2244 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Association with poorly crystalline metal Analysis of oil inclusions by fs-laser oxides: Effect on soil organic matter ablation and ToF-SIMS storage and stability in four eastern 1* 1 ROBERT POTTORF , SEBASTIEN DREYFUS , SANDRA 2 3 deciduous forest soils SILJESTRÖM , CHRISTOPHE PECHEYRAN , BENOIT 3 1 1 CATALAYUD , NGAMI PHAN , AND MARLENE MADINCEA 1* 2 3 R. Porras , M.Torn , K. McFarlane 1ExxonMobil Upstream Research, Houston, USA [email protected] (* presenting author) 2 1Lawrence Berkeley National Laboratory, Berkeley, CA, USA, SP Technical Research Institute of Sweden, Boråas, Sweden [email protected] [email protected] (*presenting author) 3IPREM, LCABIE, UMR 5254, Pau, France 2 Lawrence Berkeley National [email protected] Laboratory, Berkeley, CA, USA, [email protected] 3 Femtosecond (fs) Laser Ablation Center for Accelerator Mass Spectrometry, Lawrence Livermore Recent advances in laser technology have led to ultrashort laser National Laboratory, Livermore, CA., USA [email protected] pulses capable of selectively opening and liberating oil within single

inclusions. Coupling of an on-line femtosecond laser to a gas Redox-active metals and the global carbon cycle chromatograph-mass spectrometer successfully analysed

hydrocarbon compounds from individual inclusions [1], but C Strong association with mineral surfaces has been suggested as 19+ one mechanism underlying the long-term stabilization of organic matter in compounds were undetected and potentially remained in the ablation soils. Several recent studies have demonstrated a positive correlation chamber. To test this hypothesis, well characterized oils were between the content of poorly ordered crystalline metal oxide and ablated with an infrared (1030 nm) high repetition rate femtosecond 14 hydroxide mineral phases and soil organic matter (SOM) or C-based laser and directly collected on filters placed at the exit of the residence time. This positive correlation suggests that mineral-associated ablation chamber. Analyses of filter extracts by GCxGC-ToF-MS SOM persists over long time scales. showed the presence of unaltered C compounds including We utilized selective chemical dissolution (acid ammonium 12+ oxalate in the dark and sodium pyrophosphate) coupled with radiocarbon biomarkers. The success of the femtosecond laser as a sampling tool measurements to investigate the relationship between poorly crystalline Fe, for biomarker analysis of oils was extended to the analysis of Al, and Mn oxyhydroxide phases on organic matter storage and turnover individual inclusions. time across four deciduous forest sites in the eastern U.S.comprising three different soil orders (inceptisol, spodosol alfisol). Time of Flight Secondary Ion Mass Spectrometry (ToF- Our results demonstrate that association with poorly- SIMS) crystalline Fe and Al oxides (via adsorption to mineral surfaces and/or ToF-SIMS technology has been used to detect hopanes and formation of soluble metal-OM complexes) do slow the turnover of SOM, with a significant positive linear relationship between radiocarbon turnover steranes in single oil-bearing fluid inclusions [2]. Standard oil suites time and the content of oxalate extractable Al and Fe overall (R2= were used to calibrate the ToF-SIMS instrument for various 0.60,P=0.0001,CL=95%). Piecewise regression analysis on turnover time hydrocarbon source rock facies allowing the determination of the vs. oxalate extractable metal oxide content for all four sites shows an origin of oils trapped in inclusions within the Elk Basin Field, Big -1 apparent metal oxide threshold value at 5g kg . Sites with oxalate Horn Basin, WY. The oils appear to be derived from a distal extractable Fe and Al content below this value showed no statistically carbonate source (Phosphoria Formation) supporting long distance, significant influence on SOM stability, presumably because the metal lateral migration into the Big Horn Basin Fields from a mature oxides are present in insufficient quantity to exert a measureable influence on the decomposability of SOM. Phosphoria source rock ~65-120Ma. Soluble Fe and Al oxyhydroxide-OM complexes extracted via treatment with Na-pyrophosphate had a statistically significant influence on [1] Volk et al. (2010) Organic Geochemistry 41, 74–77. carbon storage at only one site (Bartlett Experimental Forest, spodosol) [2] Siljeström et al. (2010) Geobiology 8, 37–44. (R2=0.92, P<0.0001, 95%CL). However a significant linear relationship between 14C-based turnover time and Na-pyrophosphate extractable Fe and Al could not be demonstrated for any individual site. Thus, complexation of organic matter via reaction with Fe and Al oxide phases does not appear to be the dominant control on turnover time in the 0-15cm depth at the sites under study. Harvard Forest (inceptisol) had the highest poorly crystalline Fe concentrations estimated as (oxalate extractable Fe) – (Na-pyrophosphate extractable Fe) and exhibited the strongest influence on 14C based turnover times (R2=0.82, P=0.0003,CL=95%); in this soil, poorly-crystalline Fe oxides and hydroxides are quantitatively important in stabilizing organic inputs against decomposition. Poorly crystalline Mn was found to exert a significant influence on SOM stability at a single site: Missouri Ozark Forest (alfisol) (R2=0.65,P=0.0051,CL=95%). No significant effect for Mn on SOM storage could be demonstrated for any of the four sites under study.

Mineralogical Magazine | www.minersoc.org 2245 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Contrasted response of U-Th bearing The bulk composition of Rare Earth minerals to albitization: Elements (REE), Sc and Y in 36 chondrites: insight into elemental A case study from 3 albitite fractionation in the solar nebula occurences in the Pyrenees 1,2* 1 1 ALI POURMAND , NICOLAS DAUPHAS , THOMAS J. IRELAND 1 Origins Lab, Department of Geophysical Sciences, University of 1* 1 MARC POUJOL , PHILIPPE BOULVAIS Chicago, Chicago, IL 60637, USA 2* Neptune Isotope Lab, University of Miami - RSMAS, Miami, FL 1Université de Rennes 1, UMR CNRS 6118 Géosciences Rennes, 33149, USA, [email protected] (presenting author) 35042 Rennes cedex, France. [email protected] (*

presenting author)) Enrichment or depletion of the REE, Sc and Y in chondritic Albitization is a common metasomatic process active in various meteorites, relative to solar abundances preserved in the least geodynamic environments. In the northern Pyrenees, several equilibrated chondrites, has provided valuable insight into the occurrences of albitites are described. Like many other orogenic belts, the Pyrenees recorded condensation/evaporation history of refractory lithophile elements in numerous fluid-rock interaction events. Fluids led to talc the solar nebula during the early formation of the solar system [1-3]. mineralization in dolostones,ophicalcite development at the expense A large portion of the existing data from bulk meteorite samples and of peridotite massifs and albitization of granitoids and metamorphic their refractory inclusions, however, suffer from low precisions, or do rocks.. Because the Pyrenees have undergone the effects of both the Hercynian and Alpine orogenies, precise dating of the different fluid not include mono-isotopic elements (Pr, Tb, Ho and Tm). Recently, flow events is not straightforward. we presented novel analytical techniques, utilizing low-blank fusion In this study, we with LiBO2 flux, TODGA extraction chromatography, and MC-ICP- focused on zircon, monazite and titanite, found either in MS for measuring the isotopic composition of actinides, REE, Sc and metasedimenatry or meta- Y in extra-terrestrial materials [4], and revised the accretion age of igneous protoliths that Mars [5] and the mean of CI-chondrites for these elements [6]. Here, undergone pervasive we present bulk concentrations of REE, Sc and Y in 36 (28 falls and albitization. Zircon grains were present in all the 8 finds) carbonaceous (5), ordinary (15) and enstatite (16) chondrites studied samples. Monazites using this new analytical methodology. All meteorite groups show were found only in an varying degrees of enrichment or depletion in REE, Sc and Y relative albitite occurrence developped to the mean of CI-chondrites. In general, three types of fractionation Fig 1: Ca chemical mapping of monazite from an igneous protolith while are dominant among other irregular patterns: 1) more refractory titanites were found in a albitized metasedimentary sample. These heavy REE (Gd, Tb, Dy, Ho, Er and Lu) are enriched relative to light three types of mineral where selected in well characterized hydrothermal assemblages: zircons in metasomatically Zr-enriched REE (La, Ce, Pr, Nd, Sm and Tm), 2) more volatile elements (Eu and rocks or in hydrothermal structures (millimetric veins cross-cutting Yb) show positive or negative anomalies accompanied by minimal granitoids); monazites when associated with calcite and/or albite in fractionation in other REE, 3) all elements show relatively similar centimetric veins (Fig 1) and titanite with albite. enrichment or depletion without significant anomalies. More In-situ LA-ICP-MS ages obtained directly in thin sections from euhedral titanite and monazite grains from distinct albitites are 110 dispersion is also observed in the anomalies of more volatile elements ± 8 and 98 ± 2 Ma, respectively [1]. The zircon U-Th-Pb isotopic (e.g., Eu/Eu*) with increasing degrees of equilibration. While some system did not record this Cretaceous metasomatic event in any of fractionation patterns can be attributed to the presence of (ultra) the selected sample. This demonstrates that none of the zircons were refractory inclusions [3] or minerals (e.g., phosphate) that concentrate affected (or grew anew) during fluid circulations. This confirms the robustness of zircon with respect to interaction with fluids. REE in chondrites, other mechanisms may be needed for patterns that We argue that the total time span of 20 Ma recorded by albitites cannot be explained by dominance of a particular group of inclusions. corresponds to a long-lived hydrothermal system that was active during the rotation of Iberia around Europe. Because albitization and [1] Boynton (1975) Geochim. Cosmochim. Acta 39, 569-584. [2] talc mineralization share a common spatial and temporal distribution Evensen et al. (1978) Geochim. Cosmochim. Acta 42, 1199-1212. [3] in the Pyrenees, we argue that these two metasomatic phenomena McPherson et al. (1988) in Meteorites and the Early Solar System are two independent records of this single, regional-scale, long-lived pp. 746-807. [4] Pourmand & Dauphas (2010) Talanta 81, 741-753. hydrothermal system. [5] Dauphas & Pourmand (2011) Nature 473, 489–492. [6] Pourmand et al. (2012) Chem. Geol. 291, 38-54.

Mineralogical Magazine | www.minersoc.org 2246 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Reassesment of the rare earth elements On calculating phase equilibria for external cycle in french watersheds - a metamorphic systems 1* high potential resource for the future POWELL R 1* 2 1 3 O. POURRET , J. TUDURI , R. ARMAND , G. BAYON AND M. 1 School of Earth Sciences, University of Melbourne, Vic. 3010, 4 STEINMANN Australia, [email protected] (* presenting author)

1 HydrISE, LaSalle-Beauvais, Beauvais, France olivier.pourret@lasalle- Mike Brown has overseen a revolution in metamorphic geology, as beauvais.fr (* presenting author) an organiser of meetings, journal creator and editor, supporter of 2 BRGM, ENAG (BRGM School), Orléans, France people and contributor to the science itself. I would like to give a 3 Département Géosciences Marines, IFREMER, Plouzané, France personal view of an important part of that revolution—the 4 UMR 6249 Chrono-Environnement, Univ. Franche-Comté, Besançon, calculation of metamorphic phase equilibria: where we are, what the France challenges are, and what might be the way forward. This will be done

via consideration of methodological aspects of what is needed for The distribution of rare earth elements (REE) was studied in streams of the Armorican Massif and the Massif Central (France). The such calculations: 1) An extensive internally-consistent water chemistry of both watersheds was dominated by silicate weathering. thermodynamic dataset for the end-members of minerals, fluids and The REE distribution patterns of stream water showed, from the source to melts; 2) Activity-composition relationships for these phases, the catchment outlet, a fractionation of the upper continental crust extending into parts of composition space where there is little or no normalized REE distribution patterns from heavy REE (HREE) enriched experimental control; 3) Methods, for example for calculating phase to more flat and middle REE (MREE) enriched patterns, together with a diagrams, that take into account the “natural” variables that are likely progressive disappearance of a negative Ce anomaly. Ultrafiltration data to be critical in metamorphic systems; 4) Software that implements (at 3 or 5 kDa) showed that the ultrafiltrates had HREE-enriched patterns with negative Ce anomalies, whereas the organic colloids showed these methods, using the current best thermodynamic descriptions relatively flat patterns. These data thus suggest that the observed general of phases; and 5) An appropriately nuanced appreciation of reaction evolution from HREE-enriched to MREE-enriched patterns with distance in metamorphic rocks, for example regarding length-scales, and the is related to a growing importance of organic colloids as REE carriers likely boundaries of application of equilibrium thermodynamics in from upstream to downstream. the study of metamorphism. The REE patterns of the ultrafiltrates are very similar to seawater patterns. The REE pattern of seawater could thus be inherited from river water. Commonly, the REE patterns of ocean water are usually considered to reflect (i) the respective REE inputs from rivers, aeolian transport, hydrothermal vents and dissolution of marine carbonates and (ii) interactions with the biogeochemical cycle, involving REE-removal from surface waters by adsorption onto settling Fe-Mn particles. The strong Ce depletion and the HREE-enrichment of ocean waters are commonly attributed to the redox chemistry of Ce and to the high stability constants of HREE carbonate complexes. Nevertheless, different processes may lead to REE and/or Ce removal from solution. The most often discussed hypothesis is fractionation during estuarine mixing, enhanced by extremely high particle reactivity of the REE (e.g. with MnO2). Results from this study thus allow to reassess the REE external cycle. Indeed, the river input to the oceans has relatively flat REE patterns without Ce anomalies, whereas oceanic REE patterns exhibit strong negative Ce anomalies and HREE enrichment. Indeed, the processes at the origin of seawater REE patterns are commonly thought to occur within the ocean masses themselves. However, the results from the present study illustrate that seawater-like REE patterns already occur in the truly dissolved pool of river input. This leads us to favor a partial or complete removal of the colloidal REE pool during estuarine mixing by coagulation, as previously shown for dissolved humic acids and iron. In this latter case, REE fractionation occurs because colloidal and truly dissolved pools have different REE patterns. Thus, the REE patterns of seawater could be the combination of both intra-oceanic and riverine processes. Eventually, the Atlantic continental shelf could be considered as a potential REE trap and shelf sediments would, similar to metalliferous deep sea sediments, represent a REE potential resource and guide for exploration. This latter hypothesis will be further tested by analysing various fractions (detrital, Fe-Mn oxides, organic compounds) of sediments deposited in river estuaries at the Western Atlantic margin.

Mineralogical Magazine | www.minersoc.org 2247 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Hydromagnesite-magnesite playas: Records of atmospheric Pb deposition A model for carbon storage along the St. Lawrence Valley,

1* 2 1 IAN M. POWER ,SIOBHAN A. WILSON ,GREG M. DIPPLE , Quebec 1 AND ANNA L. HARRISON 1* 1 2 S. PRATTE , A. MUCCI , M. GARNEAU 1The University of British Columbia, Vancouver, Canada, 1 GEOTOP & Dept. of Earth and Planetary Sciences, McGill [email protected] (* presenting author), [email protected], University, Montreal, Qc, Canada H3A 2A7 [email protected] (*correspondence: [email protected]) 2Monash University, Clayton, Australia, [email protected] 2 GEOTOP & Département de Géographie, Université du Québec à Montréal, Montreal, Qc, Canada Hydromagnesite-magnesite playas (hectare-scale) are found near

the town of Atlin, British Columbia, Canada. The playas were first Ombrotrophic peat bogs provide reliable historical records of described in 1916 by Young [1] and, most recently, characterized in atmospheric metal deposition, in particular lead [1]. To date, most the context of a biogeochemical model for CO sequestration by 2 studies were carried out in Europe and served to document various Power et al. [2,3]. The weathering of ultramafic bedrock results in periods of anthropogenic activities. In contrast, records of Mg-rich groundwaters that discharge into topographic lows where atmospheric metal deposition in North America are still scarce. The microbial, geochemical and physical processes mediate carbonate objective of this study was to reconstruct the recent history of precipitation. The playas may be thought of as a natural repository of atmospheric metal deposition (Pb, As, Cd, Ni and Zn) along the St. CO . Although magnesite [MgCO ] is the most stable Mg-carbonate 2 3 Lawrence Valley (SLV). mineral, its precipitation is kinetically inhibited as a consequence of Cores (50 to 100-cm long) were collected in four peat bogs the strong hydration of Mg2+ ions [4]. As a result, the playas consist along the SLV. They were sub-sampled at 1 to 5-cm intervals and of a complex assemblage of hydrated Mg-carbonate mineral phases. analyzed for their trace metal contents (Pb, As, Cd, Ni and Zn). Aragonite [CaCO ], dypingite [Mg (CO ) (OH) ·5H O], and 3 5 3 4 2 2 Here, we present the vertical distributions of Pb and its stable nesquehonite [MgCO ·3H O] may precipitate directly from surface 3 2 isotopes (204, 205, 206, 207) in the four cores. Core chronologies and ground waters, which undergo diagenesis post-deposition. Playa were established using 210Pb for the surface horizons and 14C for the sediments at depth (up to ~3 m) were collected along a transect (90 deeper sections. Regional, natural background metal concentrations m) at 5 and 10 m intervals. The sediments are mainly composed of and isotopic signatures were established from the analysis of hydromagnesite [Mg5(CO3)4(OH)2·4H2O], but also contain magnesite. samples taken from the bottom of the bogs. When the latter were not The abundance of magnesite at the surface ranges from 7 to 40 wt.% available, values from the upper continental crust (UCC) values were across the playa. The water table (~1 m depth) coincides with a hard used [2]. Variations from these values within the cores were crust containing up to 10 wt.% lansfordite [MgCO3·5H2O]. Below ~1 compared to the isotopic composition of North American major m, the abundance of magnesite typically increases and may be up to lead-bearing ores (used for the synthesis of gasoline additive) and 87 wt.% with hydromagnesite being the remainder. The Mg- modern aerosol for U.S. and Canada (1994-1999). carbonate sediments overlay Ca-carbonate sediments containing Preliminary results show that anthropogenic Pb concentrations aragonite and dolomite [CaMg(CO3)2], which overlay increased sharply from the start of the 19th through the 20th century glaciolacustrine sediments. Electron microscopy shows that to reach a maximum between 1940-1970. The age and amplitude of magnesite forms as a distinct mineral phase and does not show this peak vary spatially along the SLV and, in some cases, can be intergrowth with hydromagnesite (Figure 1); meaning that it likely associated with specific anthropogenic activities (e.g. smelting) or does not form from dehydration of hydromagnesite. The current focus is on understanding the geochemical conditions of low-temperature the convergence of different air masses. Since the 60’s, lead magnesite formation, which has implications for the long-term concentrations have decreased rapidly, following the ban on leaded gasoline, but they have not reached pre-anthropogenic levels. storage of anthropogenic CO2 as Mg-carbonate minerals. Results show that the southwestern SLV has been more impacted by anthropogenic Pb. Stable lead isotopes analyses are ongoing and will help discriminate between different anthropogenic and natural sources of atmospheric Pb at the study sites.

[1] Shotyk et al. (1996) Earth Planet Sci Lett. 145, 1-7. [2] Wedephol (1995). Geochim. et Cosmochim. Acta 59(7), 1217- 1232. Figure 1: Low-temperature magnesite (rhombohedral crystals) forming between hydromagnesite plates (1 μm scale bar).

[1] Young (1916) GSA Report, 50-61. [2] Power et al. (2009) Chem. Geol. 206, 302-316. [3] Power et al. (2007) Geochem. Trans. 8:13 [4] Hänchen et al. (2008) Chem. Eng. Sci. 63, 1012-1028.

Mineralogical Magazine | www.minersoc.org 2248 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts CONTAMINATION, MELTING Geochemical Mapping of Mantle AND SULPHIDE Flow between Samoa and the Lau MINERALISATION IN THE BASAL Basin

RIVER VALLEY COMPLEX, ALLISON A. PRICE1*, MATTHEW G. JACKSON1, PAUL S. CANADA HALL1, JOHN M. SINTON2, MARK D. KURZ3 1* 1 1 Boston University, Dept. of Earth Sciences, Boston, MA, 02115 PREVEC , STEPHEN A. AND VILJOEN , GREG ([email protected]) 1 Dept of Geology, Rhodes University, P.O. Box 94, Grahamstown, 2 University of Hawai’i at Manoa, Dept. of Geology and Geophysics, South Africa, 6140, [email protected]* Honalulu, HI, 96822 3Woods Hole Oceanographic Institution, Dept. of Marine Chemistry, The River Valley Complex (RVC) is a Palaeoproterozoic mafic Woods Hole, MA, 02543 intrusion lying astride the ca. 1.0 Ga Grenville Front Tectonic Zone (GFTZ). The Complex is the easternmost member of a regionally The juxtaposition of the Samoan plume and the Tonga extensive pod of mafic intrusions, with contemporaneous volcanics and dykes which comprise the Huronian magmatic suite. The RVC is Trench provides a unique setting for the study of upper mantle flow. the first member of this suite to show ore-grade prospects for PGE- The Samoan plume is located only 200 km east of the northern sulphide mineralisation, as well as the sole instance of ultramafic terminus of the Tonga trench. North of the terminus, the Pacific plate cumulus rocks. The ores are associated with the Marginal Zone, “tears,” and the resulting tear creates a slab “window” allowing which is transected by a cross-cutting near-basal unit (the awkwardly named “Inclusion/Autolith-bearing zone”) which hosts both Samoan mantle to flow southward beneath the Vitiaz lineament-- autolithic and (more rarely) exotic xenolithic blocks, and has been which separates the Pacific from the Lau Basin--and into the shallow interpreted [1], on the basis of PGE and HFSE geochemistry, as the mantle of the Northern Lau Basin. The presence of high 3He/4He (up product of a late, chemically-boninitic melt, distinct from any other to 28 times atmospheric (R )) and latitudinal gradients in trace yet reported in this magmatic suite. A xenolithic fragment found in A the South Zone of the Dana Lake showing, displaying apparent element and isotopic (Sr-Nd-Pb) enrichment in the N. Lau Basin have cumulus layering (only otherwise found higher in the been attributed to the southward flow of mantle material from the lithostratigraphic sequence), a partial mantle of leucocratic selvage, nearby Samoan hotspot through the slab window. High 3He/4He and sulphide mineralisation, was sampled. The xenolith is characterised by major and trace element ratios (up to 28.1 RA) have been reported in a swath within the

geochemistry comparable to that of a granitoid (e.g., SiO2 ranging northern Lau Basin but drop rapidly to both the South (~400km south from around 56 wt.% up to nearly 80 wt.%), and features quartz and of Peggy ridge) and East (Lupton, 2009.) However, 3He/4He ratios alkali feldspar prominently. Conversely, the host rock is olivine have not been reported in the region to the West or North of the normative, shows relict cumulus textures, and has REE and other HFSE abundances about an order of magnitude lower than those in region of the infiltrating plume, so the geochemical “map” of Samoan the xenolith. Sm-Nd isotopic compositions show a range between plume material in the Lau Basin is incomplete. 2.45 εNd of around -1 to -2.3, typical of relatively uncontaminated We present He, Pb, Sr, and Nd isotopic analyses as well as Palaeoproterozoic mafic rocks regionally. However, the matrix trace element analyses for glasses in the region just to the west of the values range between +3.2 and 0, representing the first direct 3 4 evidence for depleted mantle in the Canadian Palaeoproterozoic. The location where the highest He/ He ratios were reported. The sulphide mineralogy (po-cpy-py-pn ± sp) varies in mode across the samples, which span the North Lau and North Fiji Basins, as well as traverse, with fracture-hosted cp-pn dominant in the xenolith, and submarine samples from Wallis Island, located just north of the Lau po-pn-cp in the host rock. Normalised PGE profiles show a PPGE- Basin, have 3He/4He ratios that vary between 6 and 15 R . The enriched pattern typical of magmatic sulphide-controlled PGE in A 3 4 both the host rock- and xenolith-hosted sulphides, with the added highest of the new He/ He occur in submarine lavas from Wallis feature of a negative Ru anomaly. A model involving infiltration Island, located between the northernmost portion of the Rochambeau metasomatism of fluid-rich crustal (footwall) melt is tentatively Ridge (28.1 RA) and the Samoan hotspot (up to 35 RA.) The new data proposed to facilitate sulphide liquid precipitation and 3 4 incorporation. indicate that the Samoan-plume high He/ He mantle does not spread to the west in the Lau Basin, but is confined to a narrow corridor in [1] Jobin-Bevans, L.S. (2004) Platinum-group element the Northern Lau Basin that extends from Samoa, through Wallis and mineralisation in Nipissing Gabbro intrusions and the River Valley Intrusion; unpublished Ph.D. thesis, University of Western Ontario, into a narrow region of the N. Lau Basin. However, Sr, Nd and Pb London, Ontario, Canada. 457 pp. isotopic evidence are consistent with low 3He/4He Samoan plume

material “leaking” into the N. Fiji basin as far west as Pandora Ridge. This observation places important constraints on changing mantle flow due to the evolving geometry of plume-trench juxtaposition.

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1* 2 grains from the Yangze River delta NEIL M. PRICE AND JUN-WOO KIM

1 JASON R. PRICE1*, MICHEAL TUBRETT2, AND DEREK WILTON3 McGill University, Department of Biology, Montreal, Canada, [email protected] 1Department of Earth Sciences, P.O. Box 1002, Millersville 2McGill University, Department of Biology, Montreal, Canada, University, Millersville, PA 17551-0302, USA, [email protected] (* presenting author) [email protected] (* presenting author)

2CREAIT Network, Memorial University of Newfoundland, St. Marine diatoms of the Thalassiosirales use either a Cu- John’s, NL, A1B 3X5 Canada, [email protected] containing plastocyanin (PC) or an Fe-containing cytochrome (cyt) 3Department of Earth Sciences, Memorial University of c to transfer electrons from cyt b f to photosystem I in the light Newfoundland, St. John’s, NL, A1B 3X5 Canada, 6 6 reactions of photosynthesis. Growth assays confirm that the PC- [email protected] containing strains require higher concentrations of Cu for cell

The epidote-group minerals are common accessory phases in division and contain roughly 2-3 times more cellular Cu (30.8 fmol -1 silicate rocks. These calc-silicate minerals may contain substantial Cu’ L ) than strains with cyt c6. Under steady state conditions, Cu quantities of Th, and concomitantly U. The radioactive decay of uptake rates are a linear inverse function of Cu-limited growth rates 232Th, 238U, 235U to their daughter nuclides results in the radiation- and not significantly different among PC and cyt c6-containing induced transformation from a periodic to an aperiodic structure strains. Thus, despite having greater cellular demand for Cu, diatoms termed metamictization [1]. Metamictization of epidote-group that use PC are unable to acquire extra Cu. In the presence of high minerals can increase their solubility and thus these minerals can be light, however, Cu uptake rates of PC-containing species are important sources of Ca in pore and stream waters that drain silicate increased by 2-10 fold, suggesting that Cu acquisition is somehow terranes [2]. On geologic timescales, dissolved Ca and bicarbonate light-activated. Steady state Cu uptake rate is proportional to ions from silicate mineral dissolution are carried by streams to the irradiance at both high and low Cu concentrations (Fig. 1). We are oceans where they are sequestered in Ca-carbonate minerals [3]. currently examining how light affects extracellular Cu(II) reduction Therefore, the weathering of metamict epidote-group minerals is in a number of PC and cyt c6-containing Thalassiosira species.

capable of consuming atmospheric CO2 and potentially influencing the long-term global climate. The extent of epidote-group mineral metamictization is a 75 10 High Cu Low Cu

function of age, and Th and U content, which together yield the α- )

-1 60 8

particle dose of the grain [4]. To determine the solubility threshold of d -1 epidote-group minerals, the α-particle dose of grains from the 45 6 Yangtze River delta in China have been calculated. These detrital 30 4 grains are resistant to chemical weathering and persist into fluvial mol Cu L P sediments. Delta sediments from such a large river system provide a ( ss 15 2 suite of epidote-group minerals that approximate the compositional U range and radiation damage commonly observed in nature for grains 0 0 0 100 200 300 400 500 resistant to dissolution. The grain(s) with the highest α-particle dose 0 100 200 300 400 500 thus reflect the solubility threshold for the epidote-group minerals. Irradiance (PE m-2 s-1) Irradiance (PE m-2 s-1) The Th, U, and Pb isotopic compositions of each grain were measured by laser ablation-inductively coupled plasma-mass spectrometry. 232Th-208Pb ages were corrected for common Pb using an iterative technique [5]. End-member epidote grains contain Figure 1: Steady state Cu uptake rate of Thalassiosira oceanica sufficiently low Th and U concentrations to prevent quantification of normalized to cellular volume as a function of growth irradiance. an α-particle dose, explaining, at least in part, why they are so Values are means of 3-5 replicates and error bars ± 1 std. resistant to chemical weathering. End-member allanite grains are relatively radioactive, reflect at least four sources of allanite to the delta, and yielded a maximum α-particle dose of ~3.6 x 1015 α-decays mg-1. This dose compares very favorably with that of ~3.5 x 1015 α- decays mg-1 reported for Amazon detrital zircons [6].

[1] Deer et al. (2001) Rock-Forming Minerals (2nd Edition), Disilicates and Ring Silicates 1B. [2] Price et al. (2005) American Mineralogist 90, 101-114. [3] Berner et al. (1983) American Journal of Science 283, 641-683. [4] Holland & Gottfried (1955) Acta Crystallographica 8, 291-300. [5] Chew et al. (2011) Chemical Geology 280, 200-216. [6] Balan et al. (2001) American Mineralogist 86, 1025-1033.

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Interfacial tension and nucleation Precipitation of MgCO3 at elevated behaviour of minerals (revisited) temperature and CO2 pressure 1* 1 MANUEL PRIETO , DIONISIS KATSIKOPOULOS , AND ANGELES VALENTINA PRIGIOBBE1* 1 FERNÁNDEZ-GONZÁLEZ 1 ETH Zurich, Institute of Process Engineering, Zurich, Switzerland. 1Department of Geology, University of Oviedo, Oviedo, Spain, Current address: Dept. of Petroleum and Geosystems [email protected] (* presenting author) Engineering, University of Texas at Austin, Texas, U.S.A. [email protected] (* presenting author) According to the classical nucleation theory (CNT), the nucleation rate depends strongly on the interfacial tension (V), Introduction and methods which in aqueous systems is related to the solubility by the rule that Mineral carbonation is a Carbon Capture and Storage (CSS) the higher the solubility, the lower V. Indirect estimations of V from technology that consists in fixing CO2 into stable carbonates, e.g., nucleation experiments [1] are typically used to account for magnesite (MgCO3) which can be either disposed of or reused [1]. crystallization in natural aqueous systems [2] and to model the Hydrated phases can initially form which then transform into the precipitation in sequential order of lesser and lesser soluble stable carbonate [2]. If carbonates are designed to be reused, the isochemical mineral phases according to the Ostwald step rule. In a precipitation process must be carried out under well-constrained related way, when solid solutions crystallize from supersaturated conditions which are still unknown or not fully defined [3,4,5]. aqueous solutions the distribution of the substituting ions between Here, we present the results from a MgCO3 precipitation study at the solid and the fluid phase usually differs from the equilibrium 90ºC, 120ºC, and 150ºC and at 100 bar of CO2 [6]. Batch values [3]. “More soluble” solid solution compositions are experiments were performed using a MgCl2-CO2-Na2CO3 aqueous kinetically favoured and tend to nucleate even though the aqueous system and monitored with online Raman spectroscopy. solution is less supersaturated for these compositions than for less Precipitation was modeled using a population balance equation soluble members. This effect has been modelled by considering a (PBE) [7] coupled with a geochemical model. Nucleation and linear variation of V with composition [4]. However, to the authors growth rates were described by empirical equations based on knowledge, there is no empirical study on the compositional classical nucleation theory and the birth-andspread growth evolution of V in solid solution systems. mechanism and the kinetic parameters were estimated by fitting In this work we revisit the concept of interfacial tension in the Raman spectroscopy measurements using multivariate kinetics light of recent findings that challenge the tradictional picture of modeling [8].

crystal nucleation, at least in the case of the CaCO3-H2O system [5]. Results and conclusions Our point is that, in the CNT framework, the interfacial tension must Two types of mechanisms were verified. At all investigated be considered more an “artificial” fitting parameter than a temperatures and at low magnesium concentration (CMg) MgCO3 measurable magnitude with a precise physical meaning. We show the precipitated directly (Fig. 1.a). At 120 and 150ºC and at high CMg, dependence of CNT-derived V values on the speciation model, the MgCO3 formed simultaneously with hydromagnesite which then expression chosen for the driving force, and the shape chosen for transformed into MgCO3 (Fig. 1.b). The kinetics showed no the nuclei. Special attention is paid to the polymorphic precipitation sensitivity to CMg, small sensitivity to temperature, and a significant

of CaCO3 phases. Finally, we determine the CNT-V parameters for sensitivity to supersaturation with respect to MgCO3 (SM). This intermediate members of a number of binary (virtually ideal and allowed the formulation of general rate equations for nucleation and non-ideal) solid solutions. Our results show a good correlation growth given by, respectively,

between the deviations from the ideal mixing behaviour, the 2 Je 4u 108 (19/ln SM ) , (1) solubility, and the obatined CNT-V values. Positive deviations from 2 92/31/6(19/ln SM ) ideality (positive enthalpy of mixing) correlate with negative GS 29u 10 (MM  1) ln Se , (2) deviations of Vfrom a linear trend, whereas negative deviations (tendency to ordering) correlate with positive deviations of V. In each case, the obtained V values are used to model non-equilibrium distribution coefficients, the results being in good agreement with experimental measurements reported in the literature.

[1] Söhnel (1982) J. Cryst. Growth 57, 101-108. [2] Fritz & Noguera (2009) Rev. Min. Geochem. 70, 371-410. [3] Prieto Figure 1: Online Raman spectroscopy measurements. (2009) Rev. Min. Geochem. 70, 47-85. [4] Pina & Putnis (2002) Geochim. Cosmochim. Acta 66, 185-192. [5] Gebauer, Völkel & [1] IPCC (2005). IPCC Special Report on Carbon Dioxide Capture Cölfen (2008) Science 322, 1819-1822. and Storage. Cambridge University Press, 442 pp. [2] Hänchen, Prigiobbe, Baciocchi, Mazzotti (2008). Chem. Eng. Sci. 63, 1012- 1028. [3] Sayles, Fyfe (1973) Geochim. Cosmochim. Acta 37, 87-99. [4] Zhang et al. (2000) Sandia Nat. Lab. NM 87185-0750. [5] Saldi et al. (2009) Geochim. Cosmochim. Acta 73, 5646-5657. [6] Prigiobbe, Mazzotti (2012) in preparation. [7] Randolph, Larson (1988) Theory of particulate processes Academic Press. [8] Cornel, Mazzotti (2008) Anal. Chem. 80, 9240-9249.

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1 2 1* 2 JOHN K. G. PRINCE* , BOSWELL A. WING , ROBERT H. JOHN C. PRISCU ,KEVIN P. HAND 3 4 RAINBIRD , GALEN P. HALVERSON 1Montana State University, Land Resources and Environmental Sciences, [email protected] 1Carleton University, Ottawa, Canada, [email protected] 2Jet Propulsion Laboratory, Pasadena, California, (* presenting author) [email protected] 2McGill University, Montreal, Canada, [email protected] 3Geological Survey of Canada, Ottawa, Canada, [email protected] Antarctic terrestrial environments were initially thought to be 4 McGill University, Montreal, Canada, [email protected] devoid of life. However, discoveries of microbial life in Antarctic lake ice, and within and under Antarctic glacial ice have all provided Abstract: information on the diversity and biogeochemical importance of The Neoproterozoic (1000-542Ma) is a dynamic era of Earth history, punctuated by super continental break-up, global biology to icy environments. We now know that polar microbiology glaciations, and the evolution of metazoan life [1,2,3]. During the plays a major role in biogeochemical processes on Earth and offers early to mid-Neoproterozoic, Earth’s redox budget was in a state of flux, the evidence for which is preserved in the isotopic records of new insights into the evolution and biodiversity of life on our planet. sulphur and carbon [4]. In order to constrain the initiation of this The discovery of viable microorganisms in icy environments has dynamic behaviour, we described and sampled 3 outcrop stratigraphic sections and a drill core at ~3m intervals through the extended what we know about the limits of life on Earth and provides Minto Inlet Formation of the Shaler Supergroup, which is exposed in strong evidence to show that life has successfully radiated into the Minto Inlier of NW Victoria Island, NWT. The Minto Inlet Formation is >250m thick and hosts virtually all habitats on our planet containing “free” liquid water. Icy well-preserved Neoproterozoic sulphate-rich evaporites deposited worlds beyond Earth may harbor the greatest volume of habitable in a periodically restricted intra-continental marine basin. The Minto space in the Solar System. For at least five of these worlds, Inlet Formation was deposited between ~900Ma and ~800Ma based on detrital zircon geochronology and stratigraphic correlation with considerable evidence exists to support the conclusion that oceans or well-calibrated sections in the northern Cordillera [4]. We measured seas may lie beneath the icy surfaces. The total liquid water reservoir multiple sulphur isotopes (δ34S, Δ33S) of the sulphate fraction in all of the stratigraphically controlled dataset of 67 samples. within these worlds may be some 30 to 40 times the volume of liquid Current understanding of the sulphur isotope record water on Earth. For example, data obtained from orbiters have suggests that the fraction of S buried as pyrite relative to sulphate evaporites was high, approaching 1 for most of the Proterozoic, revealed a deep ocean of liquid water beneath a thick chaotic ice through the Ediacaran, and into the early Phanerozoic [5]. We used cover on Europa where organic matter derived from comets and multiple sulphur isotope measurements of Minto Inlet Formation evaporites to constrain models of S fluxes into and out of the ocean oxidants provided by radiation from Jupiter’s magnetosphere may prior to the onset of the Cryogenian (720-635Ma). This approach yield a habitat for life and a reservoir of endogenous and exogenous suggests that the relative burial fraction of S as pyrite was extremely low (≈0.2) during the earliest stages of the deposition of the Minto substances. This vast quantity of liquid water begs the question: Can Inlet Formation. Previously, pyrite burial fractions this low had life emerge and thrive within ice and the cold, lightless oceans been recorded only at Permian-Triassic time, more than ≈600 Ma after the deposition of the Minto Inlet Formation [5]. Our results beneath many kilometers of ice? To address this broad question, indicate large scale variations in ocean redox conditions and a information on water activity, metabolic energy sources, nutrient dynamic sulphur-cycle were initiated during the early- availability, the ability of the physical environment to support growth Neoproterozoic. and reproduction, and the origin of the biological seed must be known. Studies of Earth’s subzero environments will continue to

play a crucial role in informing our understanding of habitability on

[1] Powell et al. (1993) Geology, 21, 889-892. other frozen worlds in our Solar System and guide our development [2] Hoffman et al. (1998) Science, 281, 1342-1346. of the robotic tools needed to investigate those distant environments. [3] Halverson and Hurtgen (2007) Earth and Planetary Science Letters, 263, 32-44. We will present combined laboratory, numerical, analytical, and field [4] Macdonald et al. (2010) Science, 327, 1241-1243. investigations from Earth’s polar regions to define the potential [5] Canfield and Farquhar (2009) PNAS, 106, 8123-8127. habitability of icy worlds beyond Earth.

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Canada) using stable isotope THOMAS PROHASKA1* , MONIKA HORSKY1, JOHANNA IRRGEHER techniques 1,a, ANDREAS ZITEK1, MARIA TESCHLER-NICOLA2,TIM SCHULZE-KÖNIG3AND THOMAS WALCZYK4 1* 1 BERNADETTE PROEMSE , BERNHARD MAYER , AND MICHAEL 1University of Natural Resources and Life Sciences Vienna, 2 WIESER Department of Chemistry, Division of Analytical Chemistry, 1Department of Geoscience, University of Calgary, 2500 University VIRIS Laboratory, A-3430 Tulln, Austria, Drive NW, Calgary, AB, T2N 1N4, Canada [email protected] (* presenting author) 2 [email protected] (*presenting author) Natural History Museum Vienna, Department of Anthropology, A- 21Department of Physics and Astronomy, University of Calgary, 1010 Vienna, Austria, [email protected] 3 ETH Zürich, Laboratory of Ion Beam Physics, 8093 Zürich, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada Switzerland, [email protected] 4 The Athabasca oil sands region (AOSR) in northeastern Alberta, National University of Singapore, Faculty of Science, Food Sciecne Canada, is one of the world’s largest oil reservoirs. Its heavy oil will and Technology Programme, Singapore 117543, become increasingly important as conventional energy resoures [email protected] a decline. Due to the rapid industrial development in the AOSR, there Recipient of a DOC-fFORTE-fellowship of the Austrian Academy have been increasing concerns about the impact of the emissions of Sciences

from the oil sands operations on the surrounding terrestrial and Laser ablation ICPMS is a widely established method to directly aquatic ecosystems. Stable isotope techniques may help to assess monitor and image the elemetal distribution on solid surfaces with such impact in the case where industrial emissions are isotopically small lateral resolution. The minimal sample preparation and the fact distinct from background components. In order to trace nitrogen (N) that any solid surface can be analzed irrespective of its nature and and sulfur (S) emissions released by the oil sands industry, we have composition, has made the method a versatile tool in many areas of determined chemical and isotopic compositions of various N and S science. In addition, the ability of detecting isotope specific compounds in emissions and several environmental receptors. information has increased the variety of applications sigificantly. E.g. Potential source materials such as untreated oil sand, bitumen, human and animal teeth as well as otoliths are often used for elemental sulfur from the sulfur storage block, coke and the by- migration studies. product ammonium sulfate were analyzed for either δ34S, δ15N Beside monitoring the natural isotopic variation, isotopically values or both. We also determined stable isotope ratios of sulfate enriched spikes can be used in natural systems to monitor uptake and (δ34S, δ18O), nitrate (δ15N, δ18O, and Δ17O) and ammonium (δ15N) of distribution of isotopic spikes by hard tissues after administration. stack emitted PM [1]. The nitrogen and triple oxygen isotopic 2.5 Here, we present the use of Sr isotope spikes for comparing composition (δ15N, δ18O, and Δ17O) of atmospheric nitrate in bulk calcium and strontium metabolism in the living organism and tracer deposition and throughfall as well as δ15N of atmospheric distribution within hard tissues (i.e. bones, teeth, otoliths). Our results ammonium, and δ18O and δ34S of atmospheric sulfate in throughfall give new insights into Sr metabolism and turnover. The and bulk deposition were also measured. Bio-indicators such as investigations bear an analytical challenge as spectral interferences lichens and pine needles were collected and analyzed for total N have to be accounted for when analysing Sr and Ca isotope ratios content, δ15N, total S content and δ34S. Industrial N and SO 4 with high spatial resolution using LA- ICPMS. emissions were found to be isotopically distinct. δ18O and Δ17O of

atmospheric nitrate deposition and δ18O values of atmospheric sulfate deposition showed trends towards lower values with increasing nitrate and sulfate deposition rates allowing for the quantification of industrial contributions to atmospheric nitrate [2] and sulfate deposition in the AOSR. Lichens responded to elevated N and S deposition in close proximity to the oil sands operations, whereas chemical and isotopic compositions of N and S in pine needles showed no significant industrial impact. In addition to “traditional” stable isotope techniques, we have investigated the suitability of δ98/95Mo as an environmental tracer in the AOSR and determined its value in Athabasca bitumen and air filters. Preliminary results reveal that industrial activities are associated with Mo isotope fractionation, providing a potential new tracer for industrial activities in the AOSR.

[1] Proemse, B., Mayer, B., Chow, J., and J. Watson (in review). [2] Proemse, B., Mayer, B., and M. Fenn (in review).

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1,2* 1,3 1 precipitation PRYTULAK, J , SAVAGE, P.S , HALLIDAY, A.N 1* 2 2 ALEXANDER PROYER , GERLINDE HABLER , RAINER ABART , 1University of Oxford, Oxford, UK ([email protected]) 3 1 1 RICHARD WIRTH , KURT KRENN , AND GEORG HOINKES 2Imperial College, London, UK (*[email protected]) 3Washington University, St. Louis, USA ([email protected]) 1University of Graz, Institute of Earth Sciences, Graz, Austria,

[email protected] (* presenting author) 2University of Vienna, Department of Lithospheric Research, Understanding and quantifying fractionation processes is key to Vienna, Austria, the application and interpretation of both traditional and non- 3 GFZ Potsdam, Potsdam, Germany, [email protected] traditional stable isotopes. In this study we examine the effects of

Crystallographically oriented precipitates of rutile grew within magmatic fractionation on the nascent stable vanadium (V) isotope garnet in metapelites from the Greek Rhodope during exhumation system [1, 2]. Vanadium exists in multiple valence states and G51V and cooling from eclogite and granulite facies conditions. should be strongly influenced by changing oxidation state. We Homgeneous nucleation produced a three-dimensional array of mostly acicular rutile precipitates with aspect rations between 10 present G51V of lavas from Hekla, Iceland [3]. Hekla is a fissure and 100. Rutile c-axes are inclined at an average angle of 27° to the volcano with eruptive products ranging from basalt to rhyolite with needle long axes (oblique extinction), and EBSD analysis reveals a clear but complex crystallographic orientation relationship with the remarkably coherent liquid lines of descent. The evolution from garnet host. TEM-imaging shows semi-coherent to incoherent phase basalt to basaltic andesite can be clearly related to crystal boundaries and a small but significant lattice mismatch even along those phase boundaries with the best relative match. The fractionation [e.g., 4]. In addition to Sr, Nd, Pb, U-series, and O “idiomorphic” rutile needles are terminated by low-index planes of isotopes, Hekla lavas also boast studies of stable Si [3] Li and Fe [5] garnet, the most common ones being (110), (100) and (112). Another set of micrometer-sized rutile inclusions in the same isotopes, making them arguably the best-characterized garnets is more isometric and granular and is interpreted as resulting differentiation suite in terms of non-traditional stable isotopes. from heterogeneous nucleation at dislocations; TEM-data show very 51 poor lattice match (complete incoherence along all interfaces). Hekla is therefore ideal to examine G V against a wide backdrop of Garnet from another metapelite sample shows arrays of oriented geochemical data. rutile needles embedded in a very fine grained (nanometer-sized) We concentrate on basalt to basaltic andesite lavas where V “dust” – most likely a later generation of rutile precipitates – with clear zones free of “dust” around the needles and larger precipitate- concentrations decrease sharply from ~300 ppm to ~10 ppm. We free zones (also free of needles) along the garnet rims. find a large range in G51V of ~2 ‰, which co-varies with major and The mechanism of rutile precipitation from garnet is not trivial and in fact impossible stoichiometrically unless one assumes trace elements. The crystallising mineral phases are olivine, 4+ significant amounts of Ti on the tetrahedral site in garnet [1, 2]; plagioclase, clinopyroxene and magnetite; with magnetite as the Yang et al, 2005). Hence, a mechanism called open system precipitation (OSP; Proyer et al. 2008, 2011) is invoked, defined as dominant V host. precipitation made possible by exchange of chemical components Co-variation of G51V with indices of differentiation could with external reservoirs such as the rock matrix and/or fluid 56 inclusions). Several open system reaction equations can be devised, implicate Rayleigh fractionation similar to that proposed for G Fe the most effective one being a redox reaction by which Fe 2+ from variations at Hekla [5]. No mineral-melt isotope fractionation the dodecahedral site is oxidized to Fe3+ and moves onto the 4+ factors are available, and a bulk f must be assumed. However, unlike octahedral site in order to replace exsolving Ti , accompanied by diffusion of electrons and divalent cations. Part of Ti 4+ may also be Fe, V is dominantly controlled by one phase. If Rayleigh reduced to Ti3+ because many of the large primary rutile inclusions fractionation is occurring, then magnetite must be extremely light in found in the same garnets display a colour change from brown to grayish-purple, which is typical for reduced rutile. In that case, Ti3+- order to drive the lava to the observed heavy G51V compositions. bearing overgrowths on primary rutile inclusions would be another The incorporation of V into magnetite will depend partly on the type of heterogeneously nucleated precipitate. Garnets with oriented acicular rutile precipitates are not oxygen fugacity of the system. Determining mineral-melt uncommon from high-grade amphibolite, granulite and also eclogite fractionation factors by measurement of G51V in both natural and facies rocks, but the typical garnets from such rocks are precipitate- free, and the actual geological significance – particularly the T-t experimental materials could pave the way for the use of magnetite information recorded by the various precipitate types, their size, as a unique single mineral tracer of oxygen fugacity. spatial distribution and morphology – is yet unclear. [1] Nielsen et al. (2011) Geostand. Geoanal. Res. 35, 293-306. [1] Van Roermund et al. (2000) Geological Journal 35, 209-229. [2] Prytulak et al. (2011) Geostand. Geoanal. Res. 35, 307-318. [2] Vang & Liu (2004) Chinese Science Bulletin 49/1, 70-76 [3] Proyer et al. (2009) Journal of metamorphic Geology 27, 639- [3] Savage et al. (2011) Geochim. Cosmochim. Acta 75, 6124-6139. 654. [4] Sigmarsson et al. (1992) Contrib. Min. Pet. 112, 20-34. [5] Schuessler et al. (2009) Chem. Geol. 258, 78-91.

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Analysis of emerging contaminants in Early Earth: an insight from the environmental systems combined Os-Nd-Hf isotope 1,* 1 2 1 C.J. PTACEK , D.W. BLOWES , S.J. BROWN , L.G. GROZA , systematics of Barberton komatiites 1,3 1 4 M.C. MONCUR , W.D. ROBERTSON , T. SCHEYTT , W.W. 1* 1 5 IGOR S. PUCHTEL , MATHIEU TOUBOUL , JANNE BLICHERT- WOESSNER TOFT2, AND RICHARD J. WALKER1 1University of Waterloo, Waterloo, Canada, [email protected] 1University of Maryland, College Park, MD 20742, USA, (* presenting author), [email protected] [email protected] (*presenting author), [email protected], 2Environment Canada, Burlington, Canada, [email protected] 3 [email protected] Alberta Innovates-Technology Futures, Calgary, Canada, 2 [email protected] Ecole Normale Supérieure de Lyon, 69007 Lyon, France, 4Technische Universität Berlin, Berlin, Germany, [email protected] [email protected] 5 University of Montana, Missoula, USA, We report 190Pt-186Os, 187Re-187Os, 146,147Sm-142,143Nd, and 176Lu- [email protected] 176Hf isotopic, trace lithophile, and highly siderophile element (HSE) abundance data for remarkably well preserved komatiites from the 22c. Applications of emerging geochemical and isotopic Komati and Weltevreden Formations of the Barberton Greenstone analytical techniques for integrated water resource Belt (BGB). These data provide new insights into the chemical management and environmental monitoring evolution of the early Earth. The 3.48 Ga Komati lavas are mildly depleted in LREE and Th and show strong depletions in HREE, Innovative mass spectrometry techniques make it possible to whereas the 3.26 Ga Weltevreden lavas are strongly depleted in detect emerging contaminants, including pharmaceutical compounds LREE and Th and are enriched in HREE; both systems show positive and explosives, at concentrations that are environmentally relevant. Nb and Ta anomalies. The two komatiite systems are characterized Applications of these techniques are challenging because of the very by initial J187Os of +0.34±0.10 and -0.14±0.03 and H143Nd of low concentrations of these compounds and because of the complex +0.30±0.13 and +0.41±0.11, respectively (2Vmean), indicating matrices often encountered in the environment. Sample collection evolution of their sources with time-integrated near-chondritic Re/Os methods and analytical procedures must be refined to provide and slightly suprachondritic 147Sm/144Nd. The initial H142Nd in both representative samples and analyses that can be used to assess the systems are not resolvable from that in the terrestrial standard. At the potential impacts of emerging contaminants. same time, these systems have radiogenic initial H176Hf of +1.9±0.3 Two case studies are used to illustrate steps required for the and +4.7±0.8, respectively, implying long-term evolution to the times application of tandem mass spectrometry techniques. These studies of melting with suprachondritic 176Lu/177Hf. The Weltevreden system involved refinement of sample collection techniques, analyte is also characterized by an initial 186Os/188Os of +0.22±0.03, separation methods, analyte quantification, and modifications of indicating evolution of its source with a time-integrated instrument configurations. suprachondritic Pt/Os (3.3±0.2 vs. 1.8 in chondrites). Finally, the A large nation-wide survey of explosives was conducted which sources of the two komatiite systems are calculated to have had initially involved the application of HPLC-MS/MS methods. The distinct absolute HSE abundances, containing ~50% (Komati) and HPLC-MS/MS technique required inclusion of several isotope- ~80% (Weltevreden) of the total HSE estimated for the modern labelled internal standards at multiple concentrations. Modification Primitive Mantle. The combined data require early formation and of the analytical procedure to an IC-MS/MS procedure resulted in long-term isolation of deep mantle domains enriched in majorite decreased matrix suppression effects and improved analyte and/or perovskite; these domains served as the melting source regions quantification. These modifications were particularly important for for the BGB lavas. The isolation must have occurred after 146Sm was the analysis of groundwater and saline waters. no longer extant, but before the mantle accumulated the full On-site wastewater disposal systems represent one of the complement of the HSE as a result of the late accretion. Our largest volumes of contaminated water discharged to the subsurface. combined data also require deep-sourced formation for the BGB This wastewater contains elevated concentrations of dissolved komatiites, most probably via dry melting in starting mantle plumes. organic matter, and nitrogen and phosphorus species. Interaction of The potential mantle temperatures calculated from the emplaced lava this water with natural aquifer materials also can result in the compositions are in excess of 1800ºC, thus providing evidence for presence of elevated concentrations of dissolved metals. The extremely hot conditions that existed in the early Archean mantle. quantification of trace pharmaceutical compounds within this setting requires consideration of sample acquisition methods, sampling equipment materials, the interaction of these materials with the target compounds, and sample matrix effects. Analyses of a suite of pharmaceutical compounds in the low ng L-1 were made for samples collected from wastewater dicharge areas, groundwater and DOC- rich surface water. These studies required diligent use of isotope- labelled internal standards to optimize analytical results. Based on these results, mechanisms controlling transport of these compounds can be better delineated.

Mineralogical Magazine | www.minersoc.org 2255 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts Exploring the Geomicrobiology of the Ar-39 dating of groundwater: How Río Tinto subsurface Mars analog by limiting is underground production? 1 using a life detector biochip ROLAND PURTSCHERT 1* 1 FERNANDO PUENTE-SÁNCHEZ , MERCEDES MORENO-PAZ , 1Climate and Environmental Physics, University of Bern, 1 1 1 PATRICIA CRUZ-GIL , LUIS RIVAS , MARINA POSTIGO , Switzerland, [email protected] 1 1 MANUEL J. GÓMEZ , MIRIAM GARCÍA-VILLADANGOS AND 1 39 VICTOR PARRO With a half-live of 269 years is Ar an ideal tracer for groundwater dating in the age range 50-1000 years [1]. Ground water 1Centro de Astrobiología (INTA-CSIC), Madrid, Spain, resources beyond the dating range of transient tracers such as [email protected] (*presenting author) 3 3 85 H/ He, Sf6, CFC’s and Kr become increasingly important due to

contamination and overexploitation of shallow and young Introduction: groundwater’s. A potential limitation of 39Ar dating of groundwater, The Iberian Pyritic Belt (IPB) is one of the largest massive besides the difficult sampling protocol, is the possibility of pyrite deposits in the world, and is considered as a Martian analog. underground production due to neutron activation of potassium [2]. Several studies [1][2] of the acidic, heavy metal rich-Tinto river in Over modern 39Ar concentrations have for example been observed in the IPB have revealed a surprisingly rich extreme ecosystem, yet U- and Th- rich crystalline rocks [3]. Another important factor is the little is known about the geomicrobiology of its subsurface. In a escape path and probability of 39Ar from the rock matrix into the previous work [3] we described an antibody microarray which water permeable pore space. In this review paper the importance of contains more than 200 antibodies against bacterial strains, different underground production of 39Ar is assessed. Data collected over the fractions of natural extracts, proteins, etc. and reported its last decade in numerous porous and fractured aquifers woldwide are usefulness for immunoprofiling of environmental samples and for discussed. the detection of biomarkers with different range of universality. [1] Corcho, J.A., et al., (2007). Water Resources Research,. 43, Results and conclusions: [2] Lehmann, B.E. and R. Purtschert, (1997). Appl. Geochem.,. Here we show the results obtained by using LDChip200 (Life 12(6): pp. 727-738. Dectector Chip) for immunoprofiling the whole depth of a drill in [3] Andrews, J.N., et al., (1989), Geochim. Cosmochim. Acta,. 53: the IPB at the Tinto river origin. From 0,5 to 1 g of samples from pp. 1803-1815. cores up to 160 m depth were processed for a quick analysis with the LDChip200. The results showed the presence of Gram-positive bacteria and peptides or proteins from the ferritin superfamily which might be involved in tolerance to the high iron concentrations present in the IPB subsurface. Biodiversity was also assessed by DNA extraction and analysis with a phylogenetic oligonucleotide microarray for prokaryotes [4], and by cloning and sequencing of the PCR-amplified bacterial 16s rRNA gene. Members of the Gram- positive Firmicutes group of bacteria were detected by the oligonucleotide microarray and sequencing. Sequencing also revealed sequences similar to those of nitrate and sulphate reducing bacteria. Those results allowed us to build a preliminary model of the ecosystem and provided an initial insight into the biology of the deep subsurface of the Iberian Pyritic Belt.

[1] González-Toril (2003) Appl Environ Microbiol 69(8), 4853- 65.[2] Amaral-Zettler (2002) Nature 417, 137. [3] Rivas (2008) Anal Chem, 80, 7970-9. [4] Garrido (2008) Environ Microbiol 10, 836-50.

Mineralogical Magazine | www.minersoc.org 2256 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts The Last Glacial Termination in the Transient porosity as an integral aspect of microstructural Southern Alps, New Zealand development during fluid-mineral 1,2* 1 2 A.E. PUTNAM , J.M. SCHAEFER , G.H. DENTON , M.R. reaction. 1 3 4 2 KAPLAN , D.J.A. BARRELL , B.G. ANDERSEN , S.D. BIRKEL , 1* 1 2 2,5 2,6 2 A. PUTNIS , C.V. PUTNIS AND H. AUSTRHEIM A.M. DOUGHTY , S.E. KELLEY , T.N.B. KOFFMAN , R.C. 7 1 FINKEL , AND R. SCHWARTZ 1Institut für Mineralogie, University of Münster, Münster, Germany

1 , [email protected] (* presenting author), putnisc@uni- Lamont-Doherty Earth Observatory, Palisades, NY, USA, muenster.de [email protected] (* presenting author) 2 2 PGP, University of Oslo, Norway, [email protected] Department of Earth Sciences and Climate Change Institute,

University of Maine, Orono, ME, USA. Whenever an aqueous solution interacts with a mineral with 3 GNS Science, Dunedin, New Zealand. which it is out of equilibrium the resultant dissolution process is 4University of Oslo, Oslo, Norway likely to result in an interfacial solution composition that is 5Victoria University of Wellington, Wellington, New Zealand. supersaturated with respect to different mineral or mineral solid 6University of New York at Buffalo, Buffalo, NY, USA. solution phases. At this stage the transport properties of the solution 7University of California Berkeley, Berkeley, CA, USA and the probability of nucleation within this interfacial aqueous solution will determine the subsequent behaviour of the system. If Abstract the rate-determining step in the dissolution-transport-nucleation process is the dissolution rate, the nucleation of the new mineral Resolving the timing of the last deglaciation in the Southern phase will take place at the dissolving interface. The microstructural Hemisphere can aid discrimination among proposed mechanisms for evolution of this solid-fluid two-phase product of the interface the last glacial termination. Here, we present records of glacier reaction depends on the possibility that it can continue to grow at the behavior from three former glacier catchments of the Southern Alps, expense of the parent phase i.e. that the fluid can maintain contact New Zealand, during the last glacial termination. We used 10Be with the parent phase at the migrating reaction interface. This will be surface-exposure dating and detailed glacial geomorphologic the case if the volume of the product solid formed is less than the volume of the parent phase dissolved, allowing the fluid phase to mapping to produce chronologies of well-preserved glacial occupy the difference. The solid volume deficit depends on both the landforms tracking the last deglaciation in the Southern Alps. We molar volumes of parent and product phases and their relative implemented a glaciological model to derive magnitudes and rates solubility in the interfacial fluid [1]. The volume occupied by the of paleo-snowline changes from our 10Be-dated geomorphological fluid in this two-phase reaction product can be described as a record of glacier behavior. Our glacier/palaeo-snowline porosity in the product solid. The product solid, together with the reconstruction indicates that Southern Alps ice recession and porosity which may be on a nanoscale, forms a microstructure characteristic of the reaction mechanism. As with all warming took place in two rapid pulses, separated by an interval of microstructures this is may be a transient phenomenon and cooling and glacier resurgence during late-glacial time. The timing subsequent textural equilibration (recrystallisation) in the presence of these warming pulses coincided with the initiation of stadial of fluid may eventually eliminate the porosity. In contrast to conditions in the North Atlantic Ocean. In this regard, we discuss the microstructures formed in solid-solid reactions, the closure possible role of a bipolar seesaw mechanism for initiating and temperature at which no further reaction takes place may be as low sustaining the last glacial termination in the southwest Pacific sector as room temperature. of the Southern Hemisphere. Examples of the microstructural development in natural and experimental fluid-mineral reactions will be given to illustrate these general principles [2]. The most important consequence of this mechanism is that it allows pervasive fluid flow through an initially low permeability rock and the transformation of one mineral assemblage to another [3]. A further aspect of this mechanism is the fact that within micropores a fluid can maintain a higher supersaturation than in a free fluid, and furthermore, the rate of dissolution of the parent phase will define a rate of change of supersaturation in the pores at the migrating interface. These two factors define the threshold supersaturation at which nucleation of the product phase takes place [4]. Taken together with the fact that the fluid composition within the porous parent phase will evolve in time depending on the mass transport though the interconnected porosity, modelling such an interface-coupled dissolution-precipitation process has proven to be a challenge.

[1] Pollok et al. (2011) Am.J.Sci. 311, 211-236. [2] Putnis (2009) Rev.Min.Geochem. 70, 47-85 [3] Putnis & Austrheim (2010) Geofluids, 10, 254-269 [4] Prieto et al. (1994) Journ.Cryst.Growth 142, 225-235.

Mineralogical Magazine | www.minersoc.org 2257 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/2198/2920104/gsminmag.76.6.16-P.pdf by guest on 29 September 2021 Goldschmidt 2012 Conference Abstracts The mechanism of leached layer An ab initio and Raman study of formation during mineral dissolution Co(II) complexes in water 1* 2 1* 1 2 CHRISTINE V. PUTNIS , ENCARNACION RUIZ-AGUDO , C. C. PYE , D. C. M. WHYNOT , L. APPLEGARTH , AND P. R. 2 1 2 CARLOS RODRIGUEZ-NAVARRO , AND ANDREW PUTNIS TREMAINE 1 Institut für Mineralogy, University of Münster, Münster, Germany, 1Department of Chemistry, Saint Mary’s University, Halifax, NS, *[email protected], [email protected] (*presenting Canada, [email protected] (* presenting author) author) 2 Department of Chemistry, University of Guelph, Guelph, ON, 2Department of Mineralogy and Petrology, University of Granada, Canada, [email protected] Granada, Spain, [email protected], [email protected] Abstract

The transport of metal ions under hydrothermal conditions such Many minerals and glasses dissolve non- as formation of ore bodies and as corrosion products in nuclear stoichiometrically, i.e. the elemental ratios measured in the fluid reactors are strongly influenced by temperature, pressure, and the during dissolution experiments are different to those in the solid. type of complexing ligands. It is difficult to make speciation This phenomenon results frequently in the formation of the so- measurements under extreme conditions, and the interpretation of called leached layers, which are chemically and structurally altered the measurements is not always unambiguous. Ab initio calculations zones at the fluid–solid interface depleted in some elements relative have been shown to be very useful in the interpretation of the spectra to the bulk mineral composition [1,2]. The mechanism of non- of aqueous solutions of metal ions in the presence of complexing 3+ - 2+ - 2+ - stoichiometric dissolution and leached layer formation has been a ligands, for example Sc -Cl [1], Zn -Cl [2] and Zn -Br [3]. We subject of significant research over the past decades, due to its present here our studies of cobalt(II) in the presence of water, relevance to a wide range of natural and technological weathering chloride, hydroxide, and ammonia ligands, including predictions of the Raman spectra [4], and compare with recent experimental Raman processes, as well as being critical to define kinetic laws for mineral measurements carried out at the University of Guelph. We will also reactions. In this study, in-situ nanoscale Atomic Force Microscopy discuss the stability of mixed OH-/Cl- complexes. (AFM) observations have been made of reacting surfaces during the

dissolution of two minerals: 1) a carbonate (dolomite, CaMg(CO3)2) and; 2) a silicate (wollastonite, CaSiO3), both of which are known to dissolve non-stoichiometrically under acidic conditions and/or to develop leached layers upon dissolution. Combined with chemical analyses of both the output solutions and the reacting surfaces, AFM

observations lead to a clearer understanding of the reaction mechanism. Our study gives clear evidence that a leached layer is formed via an interface-coupled dissolution-precipitation Figure 1: The hexaaquacobalt(II) and tetrachlorocobaltate(II) ions mechanism [3] in a two step process: stoichiometric dissolution of

the pristine mineral surfaces and subsequent precipitation of a

secondary phase (a Si-rich and Mg-rich surface precipitate,

respectively) from a supersaturated boundary layer of fluid in contact with the mineral surface, and not by preferential leaching of cations as postulated by most currently accepted dissolution models. Furthermore, this study demonstrates that in situ, direct observations of the reacting mineral surfaces are important to unambiguously ascertain the kinetics and mechanism of mineral dissolution. The kinetics of the process can be quantified from the measurement of etch pit spreading rates, which are unaffected by the

formation of a secondary precipitate, whose existence has been

neglected or simply not observed in the past.

References

[1] Casey et al. (1993) Nature, 366, 253-256. [2] Hellmann et al. Figure 2: Simulated Raman spectrum of hexaaquacobalt(II) based (2012) Chemical Geology, 294-295, 203-216. [3] Putnis (2009) on a HF/6-31+G* calculation. Reviews in Mineralogy and Geochemistry, 70, 87-124. [1] Pye et al. (2002) Can. J. Chem. 80, 1331-1342. [2] Pye et al. (2006) Phys. Chem. Chem. Phys. 8, 5428-5436. [3] Pye et al. (2011) J. Sol. Chem. 40, 1932-1954. [4] D. C. M. Whynot (2012), M. Sc. Thesis

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