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Sample records for 10be 26al 36cl

  1. Depth-dependent Concentrations of Cosmogenic 10Be, 26Al, 36Cl, HEc, NEc, and ARc in the Old Woman Iron Meteorite

    NASA Astrophysics Data System (ADS)

    Lavielle, B.; Nishiizumi, K.; Marti, K.; Jeannot, J.-P.; Caffee, M. W.; Finkel, R. C.

    1995-09-01

    We report measurements of 1OBe7 26AI, 36CI, and of light noble gases in 6 samples of the type IIB Old Woman iron meteorite. The aim of this work is to study the depth dependence of the production rates of cosmogenic nuclides in iron meteorites. Old Woman is a large single mass of 2753 kg. Five samples have been taken from a slice of about 100 cm x 50 cm. One other sample was located roughly 40 cm above the center of the slice in a perpendicular direction. The distances between any two samples vary from 36.5 cm to 57.5 cm. Studies of cosmogenic nuclides in samples of known locations are very useful for the validation of models describing the production of cosmogenic nuclides in meteorites. Cosmogenic radionuclides were measured by accelerator mass spectrometry at Lawrence Livermore National Laboratory. Partial results have been reported earlier [1]. Concentrations of 4He, 21Ne and 38Ar in aliquots of the samples were determined by conventional mass spectrometry using an isotopic dilution method. The ratio 3He/4He appears to be almost constant with a value of 0.12 - ().13. This is about half the value generally observed in iron meteorites. Similar low ratios have been previously observed in some irons and in chondritic metal and reflect diffusion losses of 3H 12,31. The ratios 4He/38Ar, 4He/21Ne and 36Ar/38Ar are similar to those observed in iron meteorites indicating no significant losses of 4He. The measured ratio S = 4He/21Ne which represents one of the best indicators of shielding depth in iron meteorites, varies from 310 to 375 in samples from the slice. By using this as a shielding parameter, profiles were obtained for the different nuclides investigated in this work. Systematic decreases from the surface to the center of the meteorite are observed and the center of the meteoroid can be determined. As expected from nuclear systematics, the ratio 36Cl/36Ar is almost constant. The ratio 36Cl/10Be is relatively constant with a mean value of 4.7 indicating that the

  2. Cosmogenic 10Be, 21Ne and 36Cl in sanidine and quartz from Chilean ignimbrites

    NASA Astrophysics Data System (ADS)

    Ivy-Ochs, S.; Kober, F.; Alfimov, V.; Kubik, P. W.; Synal, H.-A.

    2007-06-01

    Our initial results indicate that three cosmogenic nuclides: 10Be, 21Ne and 36Cl can be analyzed in sanidine. To uncover complex exposure histories or marked changes in denudation rates over time several nuclides with different half-lives (or stable) must be measured. Because of its shorter half-life, the combination of 36Cl and a long-lived nuclide 10Be or stable nuclide 21Ne will provide more information than the pairs 10Be and 26Al or 10Be and 21Ne (in quartz). Sanidine (alkali feldspar) is a common high temperature mineral and often dominates the phenocryst assemblage in silicic to intermediate volcanic rocks. Bedrock surfaces studied come from the Oxaya (erupted 19-23 Ma) and Lauca (erupted 2.7 Ma) ignimbrites of northern Chile. Quartz and sanidine phenocrysts coexist; therefore, we can check the viability of sanidine through direct comparison with nuclide concentrations in quartz. In addition, as quartz has no target for 36Cl in significant abundance we show that the unique power of sanidine is that 36Cl can be measured. We have obtained very good agreement between 10Be and 21Ne concentrations measured in sanidine and coexisting quartz. No meteoric 10Be was apparent in these sanidines. Concentrations of all three nuclides in mineral separates from rock sample CN309 from the Lauca ignimbrite in the Western Cordillera agree well and correspond to minimum exposure ages of 30-50 ka. 10Be and 21Ne measured in both sanidine and quartz from three rock samples from the Oxaya ignimbrite (CN19, CN23, CN104a) in the Western Escarpment record low average landscape modification rates (<0.70 m/Ma) over the last several million years. In contrast, 36Cl data from sanidine in CN23 seem to indicate shorter minimum exposures and more rapid maximum erosion rates.

  3. Aluminum 26, {sup 10}Be, and {sup 36}Cl depth profiles in the Canyon Diablo iron meteorite

    SciTech Connect

    Michlovich, E.S.; Elmore, D.; Vogt, S.; Lipschutz, M.E.; Masarik, J.; Reedy, R.C.

    1994-11-25

    The authors have measured activities of the long-lived cosmogenic radionuclides {sup 26}Al, {sup 10}Be, and {sup 36}Cl in 12 fragments of the iron meteorite Canyon Diablo and have constructed production rate-versus-depth profiles of those radionuclides. Profiles determined using differential particle fluxes calculated with the LAHET code system are in good agreement with {sup 26}Al, {sup 10}Be, and {sup 36}Cl experimental data, but the agreement for {sup 36}Cl was obtained only after neutron-induced cross sections were modified. Profiles calculated with lunar particle fluxes are much lower than experimental Canyon Diablo profiles. The cosmic ray exposure ages of most samples are near 540 m.y. 34 refs., 4 figs., 2 tabs.

  4. Shielding Effects on 10Be and 26Al in Diogenites

    NASA Astrophysics Data System (ADS)

    Welten, K. C.; Lindner, L.; van der Borg, K.; Loeken, Th.; Schultz, L.

    1995-09-01

    Due to the attenuation of primary particles and the variations in secondary part fluxes with depth, production rates of cosmogenic nuclides are affected by the s shape of the irradiated object. The effects of shielding conditions on the produduction rates of noble gases can be estimated on the basis of the cosmogenic 22Ne/21Ne r [1]. For the production of cosmogenic radionuclides, shielding studies mainly fo on large meteorites like St. Severin [2], Knyahinya [3], Chico [4] and Jilin [5] estimated preatmospheric radii between 25 and 85 cm. The 10Be and 26Al production were also measured in three smaller meteorites, but the cosmogenic 22Ne/21Ne rat were obscured by large amounts of trapped neon [6]. Therefore we carried out a systematic study on the 10Be and 26Al activities as a function of the 22Ne/21Ne in 7 non-Antarctic and 15 Antarctic diogenite samples. Diogenites show exposure long enough (>10 Ma) to have reached saturation levels for 10Be and 26Al and are similar to ordinary chondrites with respect to the target element composition fo production of 10Be, 26Al and Ne isotopes. The measured 10Be and 26Al activities were normalized to average diogenite compo on the basis of ICP and XRF measurements and the experimental production rate eq of [7] and [8]. For the Antarctic samples with known terrestrial ages [9] correc were made for radioactive decay. In figure 1, the resulting 10Be and 26Al production rates are plotted against the 22Ne/21Ne ratios, which were measured on the same The solid lines represent the results of an exponential fitting procedure, from two samples were excluded: EET83246 because of SCR-produced 26Al and LEW88008 be of an anomalously low 26Al/10Be ratio, which is not yet understood. Figure 1 illustrates that the 10Be and 26Al production rates are similarly affect shielding conditions: both 10Be and 26Al decrease about 30 - 40% when going from objects with low 22Ne/21Ne ratios (<1.10) to small objects with high 22Ne/21Ne r (>1.25). Recently

  5. Measurement of 26Al for atmospheric and climate research and the potential of 26Al/ 10Be ratios

    NASA Astrophysics Data System (ADS)

    Auer, M.; Kutschera, W.; Priller, A.; Wagenbach, D.; Wallner, A.; Wild, E. M.

    2007-06-01

    The measurement of the paired cosmogenic radionuclides 26Al and 10Be in environmental samples has potential applications in atmospheric and climate research. For this study, we report the first measurements of the 26Al/10Be atomic ratio in tropospheric aerosol samples from sites in Europe and Antarctica performed at the Vienna Environmental Research Accelerator (VERA). These initial results show that the 26Al/10Be atomic ratio in tropospheric aerosols averages 1.78 × 10-3 and does not vary significantly between the different locations. We also report results of systematic investigations of the ionization and detection efficiency which we performed to improve the measurement precision for 26Al by AMS. Maximum detection efficiencies of up to 9 × 10-4 (in units of 26Al atoms detected/initial) were achieved for chemically pure Al2O3, while for atmospheric samples we reached efficiencies of up to 2.2 × 10-4.

  6. An inter-comparison of 10Be and 26Al AMS reference standards and the 10Be half-life

    NASA Astrophysics Data System (ADS)

    Fink, David; Smith, Andrew

    2007-06-01

    We have completed a survey and inter-comparison of several 10Be and 26Al standard reference materials (SRMs) that are in routine use at various AMS laboratories to assess their relative values and the accuracy of their quoted nominal ratios. The accelerator measurement cycle, analysis procedure and setup used at the ANTARES AMS facility for this survey are described. We focused on a new set of 10Be and 26Al serial dilutions of standard reference materials (SRMs) prepared by Kuni Nishiizumii at the University of California, Berkeley, and found excellent systematic reproducibility and internal consistency. For other standard materials, minor deviations are evident even when the results have been recalibrated to a common half-life. In particular, we confirm that the NIST 10Be SRM-4325 has a 14% greater 10Be/Be ratio than that certified by NIST when it is calibrated against other SRMs whose ratios have been normalized to a common 1.5 Ma 10Be half-life. In order to investigate this apparent discrepancy, we report on the results of an absolute, normalization independent, measure of the NIST-4325 10Be/Be ratio. Within the constraints of this type of measurement and its systematic errors, we determine an absolute value for the 10Be/Be SRM-4325 ratio in the range 26,050 to 24,800 × 10-15 in support of the certified value of 26,800 × 10-15 given by NIST. We hesitate to directly infer as a consequence that the 10Be half-life is 1.34 Ma because such an inference is contingent on a direct and accurate specific activity in the parent solution, which at present is not available.

  7. In situ 10Be-26Al exposure ages at Meteor Crater, Arizona

    USGS Publications Warehouse

    Nishiizumi, K.; Kohl, C.P.; Shoemaker, E.M.; Arnold, J.R.; Klein, J.; Fink, D.; Middleton, R.

    1991-01-01

    A new method of dating the surface exposure of rocks from in situ production of 10Be and 26Al has been applied to determine the age of Meteor Crater, Arizona. A lower bound on the crater age of 49,200 ?? 1,700 years has been obtained by this method. ?? 1991.

  8. Erosion rate study at the Allchar deposit (Macedonia) based on radioactive and stable cosmogenic nuclides (26 Al, 36 Cl, 3 He, and 21 Ne)

    PubMed Central

    Cvetković, V.; Niedermann, S.; Pejović, V.; Amthauer, G.; Boev, B.; Bosch, F.; Aničin, I.; Henning, W. F.

    2016-01-01

    Abstract This paper focuses on constraining the erosion rate in the area of the Allchar Sb‐As‐Tl‐Au deposit (Macedonia). It contains the largest known reserves of lorandite (TlAsS2), which is essential for the LORanditeEXperiment (LOREX), aimed at determining the long‐term solar neutrino flux. Because the erosion history of the Allchar area is crucial for the success of LOREX, we applied terrestrial in situ cosmogenic nuclides including both radioactive (26Al and 36Cl) and stable (3He and 21Ne) nuclides in quartz, dolomite/calcite, sanidine, and diopside. The obtained results suggest that there is accordance in the values obtained by applying 26Al, 36Cl, and 21Ne for around 85% of the entire sample collection, with resulting erosion rates varying from several tens of m/Ma to ∼165 m/Ma. The samples from four locations (L‐8 CD, L1b/R, L1c/R, and L‐4/ADR) give erosion rates between 300 and 400 m/Ma. Although these localities reveal remarkably higher values, which may be explained by burial events that occurred in part of Allchar, the erosion rate estimates mostly in the range between 50 and 100 m/Ma. This range further enables us to estimate the vertical erosion rate values for the two main ore bodies Crven Dol and Centralni Deo. We also estimate that the lower and upper limits of average paleo‐depths for the ore body Centralni Deo from 4.3 Ma to the present are 250–290 and 750–790 m, respectively, whereas the upper limit of paleo‐depth for the ore body Crven Dol over the same geological age is 860 m. The estimated paleo‐depth values allow estimating the relative contributions of 205Pb derived from pp‐neutrino and fast cosmic‐ray muons, respectively, which is an important prerequisite for the LOREX experiment. PMID:27587984

  9. 26Al/10Be burial dating of Xujiayao-Houjiayao site in Nihewan Basin, northern China.

    PubMed

    Tu, Hua; Shen, Guanjun; Li, Haixu; Xie, Fei; Granger, Darryl E

    2015-01-01

    The Xujiayao-Houjiayao site in Nihewan Basin is among the most important Paleolithic sites in China for having provided a rich collection of hominin and mammalian fossils and lithic artifacts. Based on biostratigraphical correlation and exploratory results from a variety of dating methods, the site has been widely accepted as early Upper Pleistocene in time. However, more recent paleomagnetic analyses assigned a much older age of ∼500 ka (thousand years). This paper reports the application of 26Al/10Be burial dating as an independent check. Two quartz samples from a lower cultural horizon give a weighted mean age of 0.24 ± 0.05 Ma (million years, 1σ). The site is thus younger than 340 ka at 95% confidence, which is at variance with the previous paleomagnetic results. On the other hand, our result suggests an age of older than 140 ka for the site's lower cultural deposits, which is consistent with recent post-infrared infrared stimulated luminescence (pIR-IRSL) dating at 160-220 ka.

  10. Age of Zhoukoudian Homo erectus determined with (26)Al/(10)Be burial dating.

    PubMed

    Shen, Guanjun; Gao, Xing; Gao, Bin; Granger, Darryl E

    2009-03-12

    The age of Zhoukoudian Homo erectus, commonly known as 'Peking Man', has long been pursued, but has remained problematic owing to the lack of suitable dating methods. Here we report cosmogenic (26)Al/(10)Be burial dating of quartz sediments and artefacts from the lower strata of Locality 1 in the southwestern suburb of Beijing, China, where early representatives of Zhoukoudian Homo erectus were discovered. This study marks the first radioisotopic dating of any early hominin site in China beyond the range of mass spectrometric U-series dating. The weighted mean of six meaningful age measurements, 0.77 +/- 0.08 million years (Myr, mean +/- s.e.m.), provides the best age estimate for lower cultural layers 7-10. Together with previously reported U-series dating of speleothem calcite and palaeomagnetic stratigraphy, as well as sedimentological considerations, these layers may be further correlated to S6-S7 in Chinese loess stratigraphy or marine isotope stages (MIS) 17-19, in the range of approximately 0.68 to 0.78 Myr ago. These ages are substantially older than previously supposed and may imply early hominin's presence at the site in northern China through a relatively mild glacial period corresponding to MIS 18.

  11. 26Al/10Be Burial Dating of Xujiayao-Houjiayao Site in Nihewan Basin, Northern China

    PubMed Central

    Tu, Hua; Shen, Guanjun; Li, Haixu; Xie, Fei; Granger, Darryl E.

    2015-01-01

    The Xujiayao-Houjiayao site in Nihewan Basin is among the most important Paleolithic sites in China for having provided a rich collection of hominin and mammalian fossils and lithic artifacts. Based on biostratigraphical correlation and exploratory results from a variety of dating methods, the site has been widely accepted as early Upper Pleistocene in time. However, more recent paleomagnetic analyses assigned a much older age of ∼500 ka (thousand years). This paper reports the application of 26Al/10Be burial dating as an independent check. Two quartz samples from a lower cultural horizon give a weighted mean age of 0.24 ± 0.05 Ma (million years, 1σ). The site is thus younger than 340 ka at 95% confidence, which is at variance with the previous paleomagnetic results. On the other hand, our result suggests an age of older than 140 ka for the site’s lower cultural deposits, which is consistent with recent post-infrared infrared stimulated luminescence (pIR-IRSL) dating at 160–220 ka. PMID:25706272

  12. Dating Plio-Pleistocene glacial sediments using the cosmic-ray-produced radionuclides 10Be and 26Al

    USGS Publications Warehouse

    Balco, G.; Stone, J.O.H.; Jennings, C.

    2005-01-01

    We use the cosmic-ray-produced radionuclides 26Al and 10Be to date Plio-Pleistocene glacial sediment sequences. These two nuclides are produced in quartz at a fixed ratio, but have different decay constants. If a sample is exposed at the surface for a time and then buried by overburden and thus removed from the cosmic-ray flux, the 26Al/10Be ratio is related to the duration of burial. We first attempted to date pre-Wisconsinan tills by measuring 26Al and 10Be in fluvial sediments beneath them and applying the method of "burial dating," which previous authors have used to date river sediment carried into caves. This method, however, requires simplifying assumptions about the 26Al and 10Be concentrations in the sediment at the time of burial. We show that these assumptions are not valid for river sediment in glaciated regions. 26Al and 10Be analyses of such sediment do not provide accurate ages for these tills, although they do yield limiting ages in some cases. We overcome this difficulty by instead measuring 26Al and 10Be in quartz from paleosols that are buried by tills. We use a more general mathematical approach to determine the initial nuclide concentrations in the paleosol at the time it was buried, as well as the duration of burial. This technique provides a widely applicable improvement on other means of dating Plio-Pleistocene terrestrial glacial sediments, as well as a framework for applying cosmogenic-nuclide dating techniques in complicated stratigraphic settings. We apply it to pre-Wisconsinan glacial sediment sequences in southwest Minnesota and eastern South Dakota. Pre-Wisconsinan tills underlying the Minnesota River Valley were deposited 0.5 to 1.5 Ma, and tills beneath the Prairie Coteau in eastern South Dakota and adjacent Minnesota were deposited 1 to 2 Ma.

  13. Dating chert using in-situ produced 10Be: Possible complications revealed on landslide scarps through a comparison with 36Cl applied to coexisting limestone.

    NASA Astrophysics Data System (ADS)

    Zerathe, Swann; Braucher, Régis; Lebourg, Thomas; Leani, Leatitia; Manetti, Michel; Bourles, Didier

    2013-04-01

    This abstract and presentation highlights potential complications that may arise while using in situ produced 10Be to date diagenetic silica (chert)exposure or burial event. The initiation and evolution of large gravitational collapses in sedimentary rocks were constrained using cosmic ray exposure dating. Because these collapses occurred in a stratigraphic level composed of chert (diagenetic silica) concretions interbedded in limestone layers, their development was studied by performing in situ-produced 36Cl and 10Be concentration measurements in both the limestone and coexisting diagenetic silica (chert), respectively. Following the routinely used decontamination and preparation protocols for 10Be produced in diagenetic silica, large discrepancies were observed with exposure ages determined by 36Cl within carbonate for samples originating from the same scarp. While 36Cl exposure ages were clustered as expected for a unique single gravitational event, 10Be exposure ages were scattered along the same studied scarps. To determine the origin of such a bias, petrological investigations were carried out for chert (diagenetic silica). Thin sections highlighted a complex mineralogical texture characterized by remnant silicified ooids showing calcitic cores, calcite inclusions and a dominant amorphous hydrated silica (grain > 20 μm). To decipher and characterize the potential origins of the excess measured 10Be within diagenetic silica, all samples were first reprocessed following the routine decontamination protocol (HCL-H2SiF6 leachings and three partial HF dissolutions) but starting from three different grain size fractions (GS1: 1000-500, GS2: 500-250 and GS3: 250-50 μm). The resulting concentrations clearly showed a decreasing 10Be content as a function of the grain size, but still yielded 10Be exposure ages significantly higher than 36Cl counterparts. Because potential adsorption of 10Be at the surface of amorphous silica grains was suspected, partial dissolution

  14. Examination of surface exposure age of Antarctic moraines using in situ produced [sup 10]Be and [sup 26]Al

    SciTech Connect

    Brown, E.T.; Edmond, J.M. ); Raisbeck, G.M.; Yiou, F. ); Kurz, M.D.; Brook, E.J. )

    1991-08-01

    Concentrations of [sup 10]Be (t[sub 1/2] = 1.5 [times] 10[sup 6]y) and [sup 26]Al (t[sub 1/2] = 0.72 [times] 10[sup 6]y) have been determined by accelerator mass spectrometry (AMS) in a suite of quartz samples taken from sandstone boulders in several moraines in Arena Valley, a dry valley adjacent to the Taylor Glacier in the Quatermain Mountains, Southern Victoria Land, East Antarctica. These isotopes are produced in surficial quartz by cosmic ray spallation of O and Si. The concentrations in these samples ranged from 6.1 [times] 10[sup 5] to 3.0 [times] 10[sup 7] at g[sup [minus]1] for [sup 10]Be and from 9.4 [times] 10[sup 6] to 1.2 [times] 10[sup 8] at g[sup [minus]1] for [sup 26]Al, depending upon the extent of exposure at the surface. Production rates of 17[sub [minus]4][sup +16] at g[sup [minus]1]y[sup [minus]1] for [sup 10]Be and 113[sub [minus]16][sup +54] at g[sup [minus]1]y[sup [minus]1] for [sup 26]Al at 1300 m and 87[degree]S and a [sup 26]Al:[sup 10]Be production ratio of 6.5[sub [minus]1.3][sup +1.3] were calculated from the data. These values correspond to sea-level production rates at high geomagnetic latitude of 6.4 at g[sup [minus]1]y[sup [minus]1] and 41.7 at g[sup [minus]1]y[sup [minus]1] for [sup 10]Be and [sup 26]Al, respectively, consistent with determinations based on [approximately]11 Ky glacially polished surfaces in the Sierra Nevada in California. These production rates imply exposure ages for the various moraines ranging from 50 Ky to 2.5 My, in accordance with other geological evidence. The [sup 10]Be and [sup 26]Al ages of these rocks compare favorably with those found using a similar dating method based on in situ production of [sup 3]He.

  15. Dating offset fans along the Mojave section of the San Andreas fault using cosmogenic 26Al and 10Be

    USGS Publications Warehouse

    Matmon, A.; Schwartz, D.P.; Finkel, R.; Clemmens, S.; Hanks, T.

    2005-01-01

    Analysis of cosmogenic 10Be and 26Al in samples collected from exposed boulders (n = 20) and from buried sediment (n = 3) from offset fans along the San Andreas fault near Little Rock, California, yielded ages, ranging from 16 to 413 ka, which increase with distance from their source at the mouth of Little Rock Creek. In order to determine the age of the relatively younger fans, the erosion rate of the boulders and the cosmogenic nuclide inheritance from exposure prior to deposition in the fan were established. Cosmogenic nuclide inheritance values that range between 8.5 ?? 103 and 196 ?? 103 atoms 10Be g-1 quartz were determined by measuring the concentrations and ratios of 10Be and 26Al in boulders (n = 10) and fine sediment (n = 7) at the outlet of the present active stream. Boulder erosion rate, ranging between 17 and 160 mm k.y.-1, was estimated by measuring 10Be and 26Al concentrations in nearby bedrock outcrops (n = 8). Since the boulders on the fans represent the most resistant rocks in this environment, we used the lowest rate for the age calculations. Monte Carlo simulations were used to determine ages of 16 ?? 5 and 29 ?? 7 ka for the two younger fan surfaces. Older fans (older than 100 ka) were dated by analyzing 10Be and 26Al concentrations in buried sand samples. The ages of the three oldest fans range between 227 ?? 242 and 413 ?? 185 ka. Although fan age determinations are accompanied by large uncertainties, the results of this study show a clear trend of increasing fan ages with increasing distance from the source near Little Rock Creek and provide a long-term slip rate along this section of the San Andreas fault. Slip rate along the Mojave section of the San Andreas fault for the past 413 k.y. can be determined in several ways. The average slip rate calculated from the individual fan ages is 4.2 ?? 0.9 cm yr-1. A linear regression through the data points implies a slip rate of 3.7 ?? 1.0 cm yr-1. A most probable slip rate of 3.0 ?? 1.0 cm yr-1 is

  16. 26Al/10Be dating of an aeolian dust mantle soil in western New South Wales, Australia

    NASA Astrophysics Data System (ADS)

    Fisher, Adrian; Fink, David; Chappell, John; Melville, Michael

    2014-08-01

    Aeolian dust mantle soils are an important element of many landscapes in south-eastern Australia, though the age of these aeolian deposits has not been radiometrically determined. At Fowlers Gap in western New South Wales, surface cobbles of silcrete and quartz overlie a stone-free, aeolian dust mantle soil, which has a thickness of about 1.6 m. The clay-rich aeolian dust deposit in turn lies upon a buried silcrete and quartz stone layer. Modelling in-situ cosmogenic 26Al and 10Be concentrations measured in both the surface quartz stones and in the buried quartz layer of rocks, reveals that each has experienced a complex exposure-burial history. Due to the absence of quartz stones or sand at intermediate depths, our cosmogenic 26Al and 10Be modelling was not able to determine a definitive mechanism of stone pavement formation and stone burial. Various scenarios of stone formation, transport, burial and exhumation were tested that constrain the age of the deposit to range from 0.9 ± 0.2 Ma to 1.8 ± 0.2 Ma, based largely on different assumptions taken for the time-dependency of the net sedimentation rate. This corresponds with the initiation of the Simpson Desert dune fields and the deflation of lakes in central Australia, which probably responded to the shift to longer-wavelength, larger-amplitude Quaternary glacial cycles at around 1 Ma. Sensitivity analyses were carried out to identify those parameters which better constrained model outputs. Within model errors, which largely are the result of analytical errors in measured 26Al and 10Be concentrations, all three competing theories of colluvial wash, upward displacement of stones, and cumulic pedogenesis are possible mechanisms for the formation of the surface stone pavement.

  17. Potentials and pitfalls of depth profile (10Be), burial isochron (26Al/10Be) and palaeomagnetic techniques for dating Early Pleistocene terrace deposits of the Moselle valley (Germany)

    NASA Astrophysics Data System (ADS)

    Rixhon, Gilles; Cordier, Stéphane; May, Simon Matthias; Kelterbaum, Daniel; Szemkus, Nina; Keulertz, Rebecca; Dunai, Tibor; Binnie, Steven; Hambach, Ulrich; Scheidt, Stephanie; Brueckner, Helmut

    2016-04-01

    Throughout the river network of the Rhenish Massif the so-called main terraces complex (MTC) forms the morphological transition between a wide upper palaeovalley and a deeply incised lower valley. The youngest level of this complex (YMT), directly located at the edge of the incised valley, represents a dominant geomorphic feature; it is often used as a reference level to identify the beginning of the main middle Pleistocene incision episode (Demoulin & Hallot, 2009). Although the main terraces are particularly well preserved in the lower Moselle valley, a questionable age of ca. 800 ka is assumed for the YMT, mainly based on the uncertain extrapolation of controversially interpreted palaeomagnetic data obtained in the Rhine valley. In this study, we applied terrestrial cosmogenic nuclide (TCN) dating (10Be/26Al) and palaeomagnetic dating to Moselle fluvial sediments of the MTC. To unravel the spatio-temporal characteristics of the Pleistocene evolution of the valley, several sites along the lower Moselle were sampled following two distinct TCN dating strategies: depth profiles where the original terrace (palaeo-) surface is well preserved and did not experience a major post-depositional burial (e.g., loess cover); and the isochron technique, where the sediment thickness exceeds 4.5-5 m. One terrace deposit was sampled for both approaches (reference site). In addition, palaeomagnetic sampling was systematically performed in each terrace sampled for TCN measurements. The TCN dating techniques show contrasting results for our reference site. Three main issues are observed for the depth profile method: (i) an inability of the modeled profile to constrain the 10Be concentration of the uppermost sample; (ii) an overestimated density value as model output; and (iii) a probable concentration steady state of the terrace deposits. By contrast, the isochron method yields a burial age estimate of 1.26 +0.29/-0.25 Ma, although one sample showed a depleted 26Al/10Be ratio

  18. Eroding and Inflating the Atacama Desert, Chile: Insights Through Cosmogenic 10-Be, 26-Al and 21-Ne

    NASA Astrophysics Data System (ADS)

    Heimsath, A. M.; Jungers, M. C.; Amundson, R.; Balco, G.; Shuster, D. L.

    2010-12-01

    Enigmas of the Atacama Desert are as abundant as the hypotheses formulated to explain them. This fascinating and extreme landscape attracts scientists from disparate disciplines, spawning remarkable insights into the connections between climate, tectonics, biota and landscape evolution. Recent work explores such connections on timescales ranging from millions to thousands of years. Both the timing of the onset of hyperaridity in the Atacama and its relationship to the uplift of the Andes are especially well-debated topics. Similarly enigmatic, but less widely studied, are the connections between the timing of hyperaridity and the surface morphology of the region. Specifically, the extent, nature, and timing of formation for the extensive salars across the Atacama are undeniably linked to the climate history of the region. Adjacent to the extensive salars are landscapes that appear to be shaped by processes more typically associated with temperate landscapes: rilling and gullying, extensive terrace deposition, steep fault scarps, landslide deposits, and extensive fan and paleosurface deposits. Our primary goal in this project is to establish chronologies and rates for the surface processes driving landscape evolution for two field regions in the Atacama. To achieve this goal we are also testing and expanding upon the burial dating methodology (Balco and Shuster, 2009) that couples the stable cosmogenic nuclide, 21Ne, with the radiogenic nuclides, 10Be and 26Al. Here we present new results from remarkably different field settings from the north-central Atacama. The southern region, inland from Antofagasta, is relatively well studied to determine how the onset of hyperaridity impacted water-driven processes. The northern region, north of the Rio Loa and Calama, differs most notably by the enormous basin fills of salt (e.g. Salar de Llamara and Salar Grande) and evidence of more extensive recently active salars. Across both regions we use in 10Be, 26Al, and 21Ne to

  19. Rates of sediment supply to arroyos from upland erosion determined using in situ produced cosmogenic 10Be and 26Al

    USGS Publications Warehouse

    Clapp, Erik M.; Bierman, Paul R.; Nichols, Kyle K.; Pavich, Milan; Caffee, Marc A.

    2001-01-01

    Using 10Be and 26Al measured in sediment and bedrock, we quantify rates of upland erosion and sediment supply to a small basin in northwestern New Mexico. This and many other similar basins in the southwestern United States have been affected by cycles of arroyo incision and backfilling several times in the past few millennia. The sediment generation (275 ± 65 g m−2 yr−1) and bedrock equivalent lowering rates (102 ± 24 m myr−1) we determine are sufficient to support at least three arroyo cycles in the past 3,000 years, consistent with rates calculated from a physical sediment budget within the basin and regional rates determined using other techniques. Nuclide concentrations measured in different sediment sources and reservoirs suggest that the arroyo is a good spatial and temporal integrator of sediment and associated nuclide concentrations from throughout the basin, that the basin is in steady-state, and that nuclide concentration is independent of sediment grain size. Differences between nuclide concentrations measured in sediment sources and reservoirs reflect sediment residence times and indicate that subcolluvial bedrock weathering on hillslopes supplies more sediment to the basin than erosion of exposed bedrock.

  20. Production of cosmogenic isotopes 7Be, 10Be, 14C, 22Na, and 36Cl in the atmosphere: Altitudinal profiles of yield functions

    NASA Astrophysics Data System (ADS)

    Poluianov, S. V.; Kovaltsov, G. A.; Mishev, A. L.; Usoskin, I. G.

    2016-07-01

    New consistent and precise computations of the production of five cosmogenic radioisotopes, 7Be, 10Be, 14C, 22Na, and 36Cl, in the Earth's atmosphere by cosmic rays are presented in the form of tabulated yield functions. For the first time, a detailed set of the altitude profiles of the production functions is provided which makes it possible to apply the results directly as input for atmospheric transport models. Good agreement with most of the earlier published works for columnar and global isotopic production rates is shown. Altitude profiles of the production are important, in particular for such tasks as studies of strong solar particle events in the past, precise reconstructions of solar activity on long-term scale, tracing air mass dynamics using cosmogenic radioisotopes, etc. As an example, computations of the 10Be deposition flux in the polar region are shown for the last decades and also for a period around 780 A.D. and confronted with the actual measurements in Greenland and Antarctic ice cores.

  1. Cosmogenic 10Be and 36Cl geochronology of offset alluvial fans along the northern Death Valley fault zone: Implications for transient strain in the eastern California shear zone

    USGS Publications Warehouse

    Frankel, K.L.; Brantley, K.S.; Dolan, J.F.; Finkel, R.C.; Klinger, R.E.; Knott, J.R.; Machette, M.N.; Owen, L.A.; Phillips, F.M.; Slate, J.L.; Wernicke, B.P.

    2007-01-01

    The northern Death Valley fault zone (NDVFZ) has long been recognized as a major right-lateral strike-slip fault in the eastern California shear zone (ECSZ). However, its geologic slip rate has been difficult to determine. Using high-resolution digital topographic imagery and terrestrial cosmogenic nuclide dating, we present the first geochronologically determined slip rate for the NDVFZ. Our study focuses on the Red Wall Canyon alluvial fan, which exposes clean dextral offsets of seven channels. Analysis of airborne laser swath mapping data indicates ???297 ?? 9 m of right-lateral displacement on the fault system since the late Pleistocene. In situ terrestrial cosmogenic 10Be and 36C1 geochronology was used to date the Red Wall Canyon fan and a second, correlative fan also cut by the fault. Beryllium 10 dates from large cobbles and boulders provide a maximum age of 70 +22/-20 ka for the offset landforms. The minimum age of the alluvial fan deposits based on 36Cl depth profiles is 63 ?? 8 ka. Combining the offset measurement with the cosmogenic 10Be date yields a geologic fault slip rate of 4.2 +1.9/-1.1 mm yr-1, whereas the 36Cl data indicate 4.7 +0.9/-0.6 mm yr-1 of slip. Summing these slip rates with known rates on the Owens Valley, Hunter Mountain, and Stateline faults at similar latitudes suggests a total geologic slip rate across the northern ECSZ of ???8.5 to 10 mm yr-1. This rate is commensurate with the overall geodetic rate and implies that the apparent discrepancy between geologic and geodetic data observed in the Mojave section of the ECSZ does not extend north of the Garlock fault. Although the overall geodetic rates are similar, the best estimates based on geology predict higher strain rates in the eastern part of the ECSZ than to the west, whereas the observed geodetic strain is relatively constant. Copyright 2007 by the American Geophysical Union.

  2. Measurement of proton production cross sections of {sup 10}Be and {sup 26}Al from elements found in lunar rocks

    SciTech Connect

    Sisterson, J.M.; Kim, K.; Englert, P.A.J.

    1996-07-01

    Cosmic rays penetrate the lunar surface and interact with the lunar rocks to produce both radionuclides and stable nuclides. Production depth profiles for long-lived radionuclides produce in lunar rocks are measured using Accelerator Mass Spectrometry (AMS). For a particular radionuclide these production depth profiles can be interpreted to give an estimate for the solar proton flux over a time period characterized by the half life of the radionuclide under study. This analysis is possible if and only if all the cross sections for the interactions of all cosmic ray particles with all elements found in lunar rocks are well known. In practice, the most important cross sections needed are the proton production cross sections, because 98% of solar cosmic rays and {similar_to}87% of galactic cosmic rays are protons. The cross sections for the production of long-lived radionuclides were very difficult to measure before the development of AMS and only in recent years has significant progress been made in determining these essential cross sections. Oxygen and silicon are major constituents of lunar rocks. We have reported already {sup 14}C production cross sections from O and Si for proton energies 25-500 MeV, and O(p,x){sup 10}Be from 58 160 MeV[6]. Here we present new measurements for the cross sections O(p,x){sup 10}Be,O(p,x){sup 7}Be, Si(p,x){sup 7}Be,Si(p,x){sup 26}Al, and Si(p,x){sup 22}Na from {approximately}30 - 500 MeV.

  3. 26Al - 10Be cosmogenic nuclide isochron burial dating in combination with luminescence dating of two Danube terraces

    NASA Astrophysics Data System (ADS)

    Neuhuber, Stephanie; Braumann, Sandra; Lüthgens, Christopher; Fiebig, Markus; Häuselmann, Philipp; Schäfer, Jörg

    2016-04-01

    The Quaternary sediment record in the Vienna Basin is influenced by two main factors: (1) the tectonic development of a pull apart basin along a sinistral strike slip fault system between the Eastern Alps and the West Carpathians and by (2) strongly varying sediment supply during the Plio- and Pleistocene. From the Late Pannonian (8.8 Ma) onward a large-scale regional uplift (Decker et al., 2005) controls terrace formation in the Vienna Basin. The main sediment supply into the Vienna Basin originates from the Danube, and subordinately from tributaries to the south such as Piesting, Fischa, Leitha and from the north by the river March. Today the Danube forms a large floodplain that is bordered to the north by one large Pleistocene terrace, the Gänserndorf Terrace that is situated 17 m above todays water level. Farther to the east a smaller terrace, the Schlosshof Terrace, reaches 25 m above todays water level. These terrace levels are tilted by movement of underlying blocks (Peresson, 2006). Both, the Schlosshof and Gänserndorf terraces consist of successions of up to 2 m thick gravel beds with intercalated sand layers or -lenses that may locally reach thicknesses up to 0.8 m. At each terrace one gavel pit was selected to calculate the time of terrace deposition by luminescence dating in combination with 26Al/10Be cosmogenic nuclide isochrone dating (Balco and Rovery, 2008). Five quartz stones from the base of each terrace were physically and chemically processed to obtain Al and Be oxides for Acceleration Mass Spectrometry. Sand samples for luminescence dating were taken above the cosmogenic nuclide samples from the closest suitable sand body. Decker et al., 2005. QSR 24, 307-322 Peresson, 2006 Geologie der österreichischen Bundesländer Niederösterreich 255-258 Balco and Rovey, 2008. AJS 908, 1083-1114 Thanks to FWF P 23138-N19, OMAA 90öu17

  4. Formation age and geomorphologic history of the Lonar impact crater deduced from in- situ cosmogenic 10Be and 26Al

    NASA Astrophysics Data System (ADS)

    Nakamura, A.; Yokoyama, Y.; Sekine, Y.; Goto, K.; Komatsu, G.; Kumar, P.; Matsuzaki, H.; Matsui, T.

    2013-12-01

    Impact cratering is a dominant surface modification process on planetary surfaces. In the inner solar system, the large majority of impacts occur on bodies covered by primitive igneous rocks. However, most of the impacts remaining on Earth surface are on different rock types than that of the inner planet and hence geologic knowledge derived from Earth's surface cannot be translated readily. The Lonar crater is a 1.88-km-diameter crater located on the Deccan basaltic traps in India (ca. 65 Ma), and is one of a few craters on Earth bombarded directly on basaltic lava flows. Thus, the Lonar crater provides a rare opportunity to study impact structures on the basaltic surfaces of other terrestrial planets and the Moon. Since the ages of terrestrial impact structures is a key to understand geomorphological processes after the impact, various dating methods have been applied to the Lonar Crater such as fission track (Storzer and Koeberl, 2004), radiocarbon (Maloof, 2010), thermoluminescence (Sengupta et al., 1997), and 40Ar/39Ar (Jourdan et al., 2011). Yet, a large discrepancy between these methods ranging from ca. 1.79 to 570 ka has been resulted. Here we report surface exposure ages based on in-situ cosmogenic 10Be and 26Al in order to obtain a precise age of the Lonar crater formation as well as to study the geomorphologic evolution. The samples are collected from the topographic highs on the rim of the crater and from the ejecta blanket. Exposure ages together with newly obtained radiocarbon age of pre-impact soil indicate much younger ages than that of obtained from 40Ar/39Ar method. This suggests the potential bias because of inherited 40Ar in impact glass. Systematically young exposure age from the rim samples compared to the samples from the ejecta blanket indicate that the rim of the Lonar crater is being actively eroded. Spatial distributions of geomorphic ages observed from the Lonar creator is not the same as the pattern reported from the well

  5. Quaternary downcutting rate of the new river, Virginia, measured from differential decay of cosmogenic {sup 26}Al and {sup 10}Be in cave-deposited alluvium

    SciTech Connect

    Granger, D.E.; Kirchner, J.W.; Finkel, R.C.

    1997-02-01

    The concentrations of the cosmogenic radionuclides {sup 26}Al and {sup 10}Be in quartz can be used to date sediment burial. Here we use {sup 26} Al and {sup 10}Be in cave-deposited river sediment to infer the time of sediment emplacement. Sediment burial dates from a vertical sequence of caves along the New River constrain its Quaternary downcutting rate to 27.3{+-}4.5 m/m.y. and may provide evidence of regional tectonic tilt. 32 refs., 3 figs., 1 tab.

  6. Measurement of proton production cross sections of (sup 10)Be and (sup 26)Al from elements found in lunar rocks

    NASA Technical Reports Server (NTRS)

    Sisterson, J. M.; Kim, K.; Englert, P. A. J.; Caffee, M.; Jull, A. J. T.; Donahue, D. J.; McHargue, L.; Castaneda, C.; Vincent, J.; Reedy, R. C.

    1996-01-01

    Cosmic rays penetrate the lunar surface and interact with the lunar rocks to produce both radionuclides and stable nuclides. Production depth profiles for long-lived radionuclides produce in lunar rocks are measured using Accelerator Mass Spectrometry (AMS). For a particular radionuclide these production depth profiles can be interpreted to give an estimate for the solar proton flux over a time period characterized by the half life of the radionuclide under study. This analysis is possible if and only if all the cross sections for the interactions of all cosmic ray particles with all elements found in lunar rocks are well known. In practice, the most important cross sections needed are the proton production cross sections, because 98% of solar cosmic rays and (similar to)87% of galactic cosmic rays are protons. The cross sections for the production of long-lived radionuclides were very difficult to measure before the development of AMS and only in recent years has significant progress been made in determining these essential cross sections. Oxygen and silicon are major constituents of lunar rocks. We have reported already C-14 production cross sections from O and Si for proton energies 25-500 MeV, and O(p,x)(sup 10)Be from 58 160 MeV[6]. Here we present new measurements for the cross sections O(p,x)Be-10,O(p,x)Be-7, Si(p,x)Be-7,Si(p,x)Al-26, and Si(p,x)Na-22 from approximately 30 - 500 MeV.

  7. B and Mg isotopic variations in Leoville mrs-06 type B1 cai:origin of 10Be and 26Al

    NASA Astrophysics Data System (ADS)

    Chaussidon, M.; Robert, F.; Russel, S. S.; Gounelle, M.; Ash, R. D.

    2003-04-01

    The finding [1-3] in Ca-Al-rich refractory inclusions (CAI) of primitive chondrites of traces of the in situ decay of radioactive 10Be (half-life 1.5Myr) indicates that irradiation of the protosolar nebula by the young Sun in its T-Tauri phase has produced significant amounts of the Li-Be-B elements. This irradiation may have produced also some or all of the short-lived 26Al (half-life 0.7Myr) and 41Ca (half-life 0.1Myr) previously detected in CAIs. To constrain the origin of 10Be and 10Al it is important to look for coupled variations in the 10Be/9Be and 26Al/27Al ratios in CAIs and to understand the processes responsible for these variations (e.g. variations in the fluences of irradiation, secondary perturbations of the CAIs, ...) We have thus studied the Li and B isotopic compositions and the Be/Li and Be/B concentration ratios in one CAI (MRS-06) from the Leoville CV3 chondrite in which large variations of the Mg isotopic compositions showing both the in situ decay of 26Al and the secondary redistribution of Mg isotopes have been observed [4]. The results show large variations for the Li and B isotopic compositions (^7Li/^6Li ranging from 11.02±0.21 to 11.82±0.07, and 10B/11B ratios ranging from 0.2457±0.0053 to 0.2980±0.0085). The ^7Li/^6Li ratio tend to decrease towards the rim of the inclusion. The 10B/11B ratios are positively correlated with the ^9Be/11B ratios indicating the in situ decay of 10Be. However perturbations of the 10Be/B system are observed. They would correspond to an event which occurred approximately 2Myr after the formation of the CAI and the irradiation of the CAI precursors which is responsible for the 10Be observed in the core of the CAI. These perturbations seem compatible with those observed for the 26Al/Mg system but they might be due to an irradiation of the already-formed, isolated CAI which would have resulted in increased 10Be/^9Be ratios and low ^7Li/^6Li ratios in the margin of the CAI. [1] McKeegan K. D. et al. (2000

  8. Deciphering the Glacial-Interglacial Landscape History in Greenland Based on Markov Chain Monte Carlo Inversion of Existing 10Be-26Al Data

    NASA Astrophysics Data System (ADS)

    Strunk, A.; Knudsen, M. F.; Larsen, N. K.; Egholm, D. L.; Jacobsen, B. H.

    2015-12-01

    Surface exposure dating with cosmogenic nuclides is a dating method under continuous development. It is particularly useful for dating ice-sheet fluctuations in glacial environments, which is essential to increase our understanding of past climate fluctuations and glacial dynamics. Constraining the landscape history in previously glaciated terrains may be difficult, however, due to unknown erosion rates and the presence of inherited nuclides. The potential use of cosmogenic nuclides in landscapes with a complex history of exposure and erosion is therefore often quite limited. In this study, we investigate the landscape history in eastern and western Greenland by applying a novel Markov Chain Monte Carlo (MCMC) inversion approach to the existing 10Be-26Al data from these regions. The new MCMC approach allows us to constrain the most likely landscape history based on comparisons between simulated and measured cosmogenic nuclide concentrations. It is a fundamental assumption of the model approach that the exposure history at the site/location can be divided into two distinct regimes: i) interglacial periods characterized by zero shielding due to overlying ice and a uniform interglacial erosion rate, and ii) glacial periods characterized by 100 % shielding and a uniform glacial erosion rate. We incorporate the exposure/burial history in the model framework by applying a threshold value to the global marine benthic d18O record and include the threshold value as a free model parameter, hereby taking into account global changes in climate. The other free parameters include the glacial and interglacial erosion rates as well as the timing of the Holocene deglaciation. The model essentially simulates numerous different landscape scenarios based on these four parameters and zooms in on the most plausible combination of model parameters. Here, we apply the MCMC-model to the concentrations of 10Be and 26Al measured in three previous studies of glacial fluctuations in Greenland

  9. Quantifying denudation rates on inselbergs in the central Namib Desert using in situ-produced cosmogenic {sup 10}Be and {sup 26}Al

    SciTech Connect

    Cockburn, H.A.P.; Summerfield, M.A.; Seidl, M.A.

    1999-05-01

    In situ-produced cosmogenic isotope concentrations in bedrock surfaces provide valuable estimates of site-specific, long-term rates of denudation and provide constraints for numerical landscape-evolution models. Measurements of cosmogenic {sup 10}Be and {sup 26}Al from graphite inselbergs in the arid to hyperarid central Namib Desert, Namibia, indicate a mean rate of summit lowering of 5.07 {+-} 1.1 m/m.y. over the past {ge} 10{sup 5} yr. The persistence of an arid climate in the region suggests that a similar rate may have prevailed for the past {approximately} 10 m.y. and possibly throughout much of the Cenozoic. Some samples have complex exposure histories that can be explained by the mode of inselberg weathering and mass wasting. The denudation rates estimated here are an order of magnitude higher than those reported for inselbergs in a significantly more humid environment in South Australia. This difference may largely be due to active salt weathering in the central Namib as a result of high levels of coastal fog precipitation.

  10. Long-term slip rate of the southern San Andreas Fault, from 10Be-26Al surface exposure dating of an offset alluvial fan

    SciTech Connect

    der Woerd, J v; Klinger, Y; Sieh, K; Tapponnier, P; Ryerson, F; M?riaux, A

    2006-01-13

    We determine the long-term slip rate of the southern San Andreas Fault in the southeastern Indio Hills using {sup 10}Be and {sup 26}Al isotopes to date an offset alluvial fan surface. Field mapping complemented with topographic data, air photos and satellite images allow to precisely determine piercing points across the fault zone that are used to measure an offset of 565 {+-} 80 m. A total of twenty-six quartz-rich cobbles from three different fan surfaces were collected and dated. The tight cluster of nuclide concentrations from 19 samples out of 20 from the offset fan surface implies a simple exposure history, negligible prior exposure and erosion, and yield an age of 35.5 {+-} 2.5 ka. The long-term slip rate of the San Andreas Fault south of Biskra Palms is thus 15.9 {+-} 3.4 mm/yr. This rate is about 10 mm/yr slower than geological (0-14 ka) and short-term geodetic estimates for this part of the San Andreas Fault implying changes in slip rate or in faulting behavior. This result puts new constraints on the slip rate of the San Jacinto and on the Eastern California Shear Zone for the last 35 ka. Our study shows that more sites along the major faults of southern California need to be targeted to better constrain the slip-rates over different time scales.

  11. The Cosmic-Ray Radioactive Nuclide 36Cl and Its Propagation in the Galaxy

    NASA Astrophysics Data System (ADS)

    Connell, J. J.; DuVernois, M. A.; Simpson, J. A.

    1998-12-01

    Radioactive 36Cl has been resolved from 35Cl and 37Cl for the first time in the cosmic radiation with measurements obtained from the high-resolution High-Energy Telescope (HET) carried on the NASA-ESA Ulysses spacecraft. Within the framework of a homogeneous propagation model wherein all 36Cl is of spallation origin, the average density of the interstellar gas ρ, through which all cosmic-ray nuclei propagate, was determined. Heliospheric modulation was included in the analysis. The abundance ratio 36Cl/Cl=5.2+/-1.8% at an average energy of 238 MeV u-1 yields ρ=0.28+0.12-0.10 atoms cm-3. Although 36Cl has a relatively short half-life (τ1/2=3.01×105 yr) compared with the approximately 20 Myr confinement or escape time Tesc for cosmic rays in the Galaxy derived from 10Be or 26Al analysis, it is shown that the confinement time based on 36Cl analysis is 18+10-6 Myr. Radioactive 10Be, 26Al, and 36Cl are all produced by nuclear interactions during propagation from Galactic sources to the observer. However, 10Be, 26Al, and 36Cl are each predominantly products of different primary cosmic-ray nuclei. 54Mn is the fourth radioactive isotope measured by the Ulysses HET. Unfortunately, its decay half-life to 54Fe is difficult to determine. Recent measurements yielded τ1/2=6.3×105 yr, leading to ρ=0.40+0.23-0.15 atoms cm-3 with a confinement time Tesc=11 Myr.

  12. Unraveling the Quaternary river incision in the Moselle valley (Rhenish Massif, Germany): new insights from cosmogenic nuclide dating (10Be/26Al) of the Main Terrace complex

    NASA Astrophysics Data System (ADS)

    Rixhon, Gilles; Cordier, Stéphane; Harmand, Dominique; May, Simon Matthias; Kelterbaum, Daniel; Dunai, Tibor; Binnie, Steven; Brückner, Helmut

    2014-05-01

    Throughout the whole river network of the Rhenish Massif, the terrace complex of the so-called Main Terrace forms the morphological transition between a wide upper palaeovalley (plateau valley) and a deeply incised lower valley. The youngest level of this Main Terrace complex (YMT), directly located at the edge of the incised valley, represents a dominant geomorphic feature in the terrace flight; it is often used as a reference level to identify the start of the main middle Pleistocene incision episode (Demoulin & Hallot, 2009). The latter probably reflects the major tectonic pulse that affected the whole Massif and was related to an acceleration of the uplift rates (Demoulin & Hallot, 2009). The Main terraces are particularly well preserved in the lower Moselle valley and are characterized by a constant absolute elevation of their base along a 150 km-long reach. Despite that various hypotheses have been proposed to explain this horizontality (updoming, faulting...), all studies assumed an age of ca. 800 ka for the YMT, mainly based on the questionable extrapolation of palaeomagnetic data obtained in the Rhine valley. Therefore, a reliable chronological framework is still required to unravel the spatio-temporal characteristics of the Pleistocene evolution of the Moselle valley. In this study, we apply cosmogenic nuclide dating (10Be/26Al) to fluvial sediments pertaining to the Main Terrace complex or to the upper Middle Terraces. Several sites along the lower Moselle were sampled following two distinct sampling strategies: (i) depth profiles where the original terrace (palaeo-)surface is well preserved and did not experience much postdepositional burial (e.g., loess cover); and (ii) the isochron technique where the sediment thickness exceeds 3 m. Cosmogenic nuclide ages recently obtained for three rivers in the Meuse catchment in the western Rhenish Massif demonstrated that the Main Terraces were younger than expected and their abandonment was diachronic along the

  13. Using 10Be and 26Al to determine sediment generation rates and identify sediment source areas in an arid region drainage basin

    NASA Astrophysics Data System (ADS)

    Clapp, Erik M.; Bierman, Paul R.; Caffee, Marc

    2002-06-01

    We measured 10Be and 26Al in 64 sediment and bedrock samples collected throughout the arid, 187 km 2 Yuma Wash drainage basin, southwestern Arizona. From the measurements, we determine long-term, time-integrated rates of upland sediment generation (81±5 g m -2 year -1) and bedrock equivalent lowering (30±2 m Ma -1) consistent with other estimates for regions of similar climate, lithology, and topography. In a small (˜8 km 2), upland sub-basin, differences in nuclide concentrations between bedrock outcrops and hillslope colluvium suggest weathering of bedrock beneath a colluvial cover is a more significant source of sediment (40×10 4 kg year -1) than weathering of exposed bedrock surfaces (10×10 4 kg year -1). Mixing models constructed from nuclide concentrations of sediment reservoirs identify important sediment source areas. Hillslope colluvium is the dominant sediment source to the upper reaches of the sub-basin channel; channel cutting of alluvial terraces is the dominant source in the lower reaches. Similarities in nuclide concentrations of various sediment reservoirs indicate short sediment storage times (<10 3 years). Nuclide concentrations, measured in channel sediment from tributaries of Yuma Wash and in samples collected along the length of the Wash, were used to construct mixing models and determine sediment sources to the main stem channel. We find an exponential decrease in the channel nuclide concentrations with distance downstream, suggesting that as much as 40% of sediment discharged from Yuma Wash has been recycled from storage within basin fill alluvium. Sediment generation and denudation rates determined from the main stem are greater (25%) than rates determined from upland sub-basins suggesting that, currently, sediment may be exported from the basin more quickly than it is being generated in the uplands. Independence of nuclide concentration and sediment grain size indicates that channels transport sediment in discrete pulses before rapidly

  14. Deglaciation of Antarctica since the Last Glacial Maximum - what can we learn from cosmogenic 10Be and 26Al exposure ages?

    NASA Astrophysics Data System (ADS)

    Fink, David

    2015-04-01

    Ice volume changes at the coastal margins of Antarctica during the global LGM are uncertain. The little evidence available suggests that behaviour of the East and West Antarctic Ice Sheets are markedly different and complex. It is hypothesised that during interglacials, thinning of the Ross Ice Shelf, a more open-water environment and increased precipitation, allowed outlet glaciers draining the Transantarctic Mnts and fed by interior Ice Sheets to advance during moist warmer periods, out of phase with colder arid periods. In contrast, glacier dynamics along the vast coastal perimeter of East Antarctica is strongly influenced by Southern Ocean conditions. Cosmogenic 10Be and 26Al chronologies, although restricted to ice-free oasis and mountains flanking drainage glaciers, has become an invaluable, if not unique, tool to quantify spatial and temporal Pleistocene ice sheet variability over the past 2 Ma. Despite an increasing number of well documented areas, extracting reliable ages from glacial deposits in polar regions is problematic. Recycling of previously exposed/ buried debris and continual post-depositional modification leads to age ambiguities for a coeval glacial landform. More importantly, passage of cold-based ice can leave a landform unmodified resulting in young erratics deposited on ancient bedrock. Advances in delivering in-situ radiocarbon to routine application offer some relief. Exposure ages from different localities throughout East Antarctica (Framnes Mnts, Lutzow-Holm Bay, Vestfold Hills) and West Antarctica (Denton Ranges, Hatherton Glacier, Shackleton Range) highlight some of the new findings. This talk presents results which quantify the magnitude and timing of paleo-ice sheet thickness changes, questions the validity of an Antarctic LGM and discusses the complexities encountered in the often excessive spread in exposure ages.

  15. Roter Kamm Impact Crater, Namibia: Age Constraints from K-Ar, Rb-Sr, Fission Track, 10Be-26Al Studies

    NASA Astrophysics Data System (ADS)

    Koeberl, C.; Klein, J.; Matsuda, J.; Nagao, K.; Reimold, W. U.; Storzer, D.

    1992-07-01

    INTRODUCTION. The Roter Kamm impact crater is located in the Namib Desert in Namibia. The impact occurred in Precambrian granitic-granodioritic orthogneisses of the 1200-900-Ma-old Namaqualand Metamorphic Complex. The granites are invaded by quartz veins and quartz-feldspar-pegmatites. Gariep metasediments probably overlaid the Namaqualand complex at the time of the impact (Reimold and Miller, 1989). Previous estimates for the crater age are not well constrained: regional geology suggests an age of 5-10 Ma, while the only available ^40Ar-^39Ar age (Hartung et al., 1991) is 3.7 Ma. Fission tracks measured in apatites from granites found on or near the crater rim were not completely reset by the impact and suggest an uplift event around 20 Ma ago (Storzer et al., 1990). We are using several approaches to bracket the age of the crater: we have measured melt breccia and pseudotachylite K-Ar ages, and apatite fission track ages in several rim granites. We are comparing Rb-Sr isotope data for rim granites with known ages of regional resetting events (Allsopp et al., 1979). Finally, we are using ^10Be-^26Al measured by accelerator mass spectrometry to determine surface exposure ages for quartz excavated during the impact event. RESULTS AND DISCUSSION. The target rock composition and stratigraphy at Roter Kamm is relatively complicated. Melt breccias formed from pegmatites, gneisses, or schists, while pseudotachylites probably formed from gneissic basement or quartz-feldspar-pegmatites (Reimold and Miller, 1989). Whole rock Rb-Sr data for several granites yield 1498 Ma, and mineral separates from sample URK-M indicate an "age" of 466 Ma; these ages are similar to those of country rocks from the general area of the northwestern Cape/southern Namibia (Allsopp et al., 1979) which indicate two widespread regional resetting events at ca. 700 Ma (related to the Pan-African orogenic deformation), and ca. 500 Ma, related to a subsequent metamorphic event. For K-Ar ages, we

  16. Cosmogenic 10Be and 26Al exposure ages of tors and erratics, Cairngorm Mountains, Scotland: Timescales for the development of a classic landscape of selective linear glacial erosion

    USGS Publications Warehouse

    Phillips, W.M.; Hall, A.M.; Mottram, R.; Fifield, L.K.; Sugden, D.E.

    2006-01-01

    The occurrence of tors within glaciated regions has been widely cited as evidence for the preservation of relic pre-Quaternary landscapes beneath protective covers of non-erosive dry-based ice. Here, we test for the preservation of pre-Quaternary landscapes with cosmogenic surface exposure dating of tors. Numerous granite tors are present on summit plateaus in the Cairngorm Mountains of Scotland where they were covered by local ice caps many times during the Pleistocene. Cosmogenic 10Be and 26Al data together with geomorphic relationships reveal that these landforms are more dynamic and younger than previously suspected. Many Cairngorm tors have been bulldozed and toppled along horizontal joints by ice motion, leaving event surfaces on tor remnants and erratics that can be dated with cosmogenic nuclides. As the surfaces have been subject to episodic burial by ice, an exposure model based upon ice and marine sediment core proxies for local glacial cover is necessary to interpret the cosmogenic nuclide data. Exposure ages and weathering characteristics of tors are closely correlated. Glacially modified tors and boulder erratics with slightly weathered surfaces have 10Be exposure ages of about 15 to 43 ka. Nuclide inheritance is present in many of these surfaces. Correction for inheritance indicates that the eastern Cairngorms were deglaciated at 15.6 ?? 0.9 ka. Glacially modified tors with moderate to advanced weathering features have 10Be exposure ages of 19 to 92 ka. These surfaces were only slightly modified during the last glacial cycle and gained much of their exposure during the interstadial of marine Oxygen Isotope Stage 5 or earlier. Tors lacking evidence of glacial modification and exhibiting advanced weathering have 10Be exposure ages between 52 and 297 ka. Nuclide concentrations in these surfaces are probably controlled by bedrock erosion rates instead of discrete glacial events. Maximum erosion rates estimated from 10Be range from 2.8 to 12.0 mm/ka, with

  17. Formation of the Short-lived Radionuclide 36Cl in the Protoplanetary Disk During Late-stage Irradiation of a Volatile-rich Reservoir

    NASA Astrophysics Data System (ADS)

    Jacobsen, Benjamin; Matzel, Jennifer; Hutcheon, Ian D.; Krot, Alexander N.; Yin, Qing-Zhu; Nagashima, Kazuhide; Ramon, Erick C.; Weber, Peter K.; Ishii, Hope A.; Ciesla, Fred J.

    2011-04-01

    Short-lived radionuclides (SLRs) in the early solar system provide fundamental insight into protoplanetary disk evolution. We measured the 36Cl-36S-isotope abundance in wadalite (<15 μm), a secondary chlorine-bearing mineral found in calcium-aluminum-rich inclusions (CAIs) in the Allende CV chondrite, to decipher the origin of the SLR 36Cl (τ 1/2 ~ 3 × 105 yr) in the early solar system. Its presence, initial abundance, and the noticeable decoupling from 26Al raise serious questions about the origin of SLRs. The inferred initial 36Cl abundance for wadalite, corresponding to a 36Cl/35Cl ratio of (1.81 ± 0.13) × 10-5, is the highest 36Cl abundance ever reported in any early solar system material. The high level of 36Cl in wadalite and the absence of 26Al (26Al/27Al <= 3.9 × 10-6) in co-existing grossular (1) unequivocally support the production of 36Cl by late-stage solar energetic particle irradiation in the protoplanetary disk and (2) indicates that the production of 36Cl, recorded by wadalite, is unrelated to the origin of 26Al and other SLRs (10Be, 53Mn) recorded by primary minerals of CAIs and chondrules. We infer that 36Cl was largely produced by irradiation of a volatile-rich reservoir in an optically thin protoplanetary disk adjacent to the region in which the CV chondrite parent asteroid accreted while the Sun was a weak T Tauri star. Subsequently, 36Cl accreted into the Allende CV chondrite together with condensed water ices.

  18. FORMATION OF THE SHORT-LIVED RADIONUCLIDE {sup 36}Cl IN THE PROTOPLANETARY DISK DURING LATE-STAGE IRRADIATION OF A VOLATILE-RICH RESERVOIR

    SciTech Connect

    Jacobsen, Benjamin; Yin Qingzhu; Matzel, Jennifer; Hutcheon, Ian D.; Ramon, Erick C.; Weber, Peter K.; Krot, Alexander N.; Nagashima, Kazuhide; Ishii, Hope A.; Ciesla, Fred J.

    2011-04-20

    Short-lived radionuclides (SLRs) in the early solar system provide fundamental insight into protoplanetary disk evolution. We measured the {sup 36}Cl-{sup 36}S-isotope abundance in wadalite (<15 {mu}m), a secondary chlorine-bearing mineral found in calcium-aluminum-rich inclusions (CAIs) in the Allende CV chondrite, to decipher the origin of the SLR {sup 36}Cl ({tau}{sub 1/2} {approx} 3 x 10{sup 5} yr) in the early solar system. Its presence, initial abundance, and the noticeable decoupling from {sup 26}Al raise serious questions about the origin of SLRs. The inferred initial {sup 36}Cl abundance for wadalite, corresponding to a {sup 36}Cl/{sup 35}Cl ratio of (1.81 {+-} 0.13) x 10{sup -5}, is the highest {sup 36}Cl abundance ever reported in any early solar system material. The high level of {sup 36}Cl in wadalite and the absence of {sup 26}Al ({sup 26}Al/{sup 27}Al {<=} 3.9 x 10{sup -6}) in co-existing grossular (1) unequivocally support the production of {sup 36}Cl by late-stage solar energetic particle irradiation in the protoplanetary disk and (2) indicates that the production of {sup 36}Cl, recorded by wadalite, is unrelated to the origin of {sup 26}Al and other SLRs ({sup 10}Be, {sup 53}Mn) recorded by primary minerals of CAIs and chondrules. We infer that {sup 36}Cl was largely produced by irradiation of a volatile-rich reservoir in an optically thin protoplanetary disk adjacent to the region in which the CV chondrite parent asteroid accreted while the Sun was a weak T Tauri star. Subsequently, {sup 36}Cl accreted into the Allende CV chondrite together with condensed water ices.

  19. Measurements of production cross sections of 10Be and 26Al by 120 GeV and 392 MeV proton bombardment of 89Y, 159Tb, and natCu targets

    DOE PAGES

    Sekimoto, S.; Okumura, S.; Yashima, H.; Matsushi, Y.; Matsuzaki, H.; Matsumura, H.; Toyoda, A.; Oishi, K.; Matsuda, N.; Kasugai, Y.; et al

    2015-08-12

    The production cross sections of 10Be and 26Al were measured by accelerator mass spectrometry using 89Y, 159Tb, and natCu targets bombarded by protons with energies Ep of 120 GeV and 392 MeV. The production cross sections obtained for 10Be and 26Al were compared with those previously reported using Ep = 50 MeV–24 GeV and various targets. It was found that the production cross sections of 10Be monotonically increased with increasing target mass number when the proton energy was greater than a few GeV. On the other hand, it was also found that the production cross sections of 10Be decreased asmore » the target mass number increased from that of carbon to those near the mass numbers of nickel and zinc when the proton energy was below approximately 1 GeV. They also increased as the target mass number increased from near those of nickel and zinc to that of bismuth, in the same proton energy range. Similar results were observed in the production cross sections of 26Al, though the absolute values were quite different between 10Be and 26Al. As a result, the difference between these production cross sections may depend on the impact parameter (nuclear radius) and/or the target nucleus stiffness.« less

  20. Measurements of the {sup 25}Mg({sup 11}B,{sup 12}C){sup 24}Na and {sup 25}Mg({sup 11}B,{sup 10}Be){sup 26}Al proton transfer reactions

    SciTech Connect

    Faria, P. N. de; Lichtenthaeler, R.; Guimaraes, V.; Lepine-Szily, A.; Benjamim, E. A.; Lima, G. F.; Moro, A. M.

    2006-08-15

    Angular distributions for the {sup 11}B+{sup 25}Mg elastic scattering, {sup 25}Mg({sup 11}B,{sup 12}C){sup 24}Na proton pickup, and {sup 25}Mg({sup 11}B,{sup 10}Be){sup 26}Al stripping reactions have been measured at E{sub {sup 11}B}=35 MeV. The angular distributions have been analyzed by the distorted-waves Born approximation calculations using the code fresco. The spectroscopic factors for the overlaps <{sup 25}Mg|{sup 26}Al>,<{sup 25}Mg|{sup 24}Na> for the ground state and excited states of {sup 26}Al and {sup 24}Na have been obtained and compared to previous measurements and shell-model calculations.

  1. Search for extinct 36Cl: Vigarano CAIs, the Pink Angel from Allende, and a Ningqiang chondrule

    NASA Astrophysics Data System (ADS)

    Nakashima, Daisuke; Ott, Ulrich; Hoppe, Peter; El Goresy, Ahmed

    2008-12-01

    We have searched for excesses of 36S derived from the decay of extinct 36Cl in sodalite, a secondary Cl-rich mineral, in Ca-Al-rich inclusions (CAIs) from the Vigarano and Allende CV3 chondrites and in a chondrule from the Ningqiang carbonaceous chondrite. The presence of sodalite in two CAIs from Vigarano and its absence from surrounding CAI fragments suggests sodalite formation after CAI fragmentation. As for sodalite in the Allende Pink Angel CAI, oxygen isotopic compositions have been interpreted as indicative of high temperature interactions, thus suggesting formation prior to accretion to the parent body, probably in a nebular setting. Sodalite in the Ningqiang chondrule is considered to have formed via alkali-Ca exchange, which is believed to have occurred before accretion to the parent body. Sodalites in the Vigarano CAIs and in the Ningqiang chondrule show no clear evidence for the presence of radiogenic 36S. The inferred 2 σ upper limits for 36Cl/ 35Cl at the time of sodalite formation are 1.6 × 10 -6 (Vigarano CAIs) and 3.3 × 10 -6 (Ningqiang chondrule), respectively. In the Pink Angel CAI sodalite exhibits small 36S excesses which weakly correlate with 35Cl/ 34S ratios. The inferred 36Cl/ 35Cl ratio of (1.8 ± 2.2) × 10 -6 (2 σ error) is lower than that found by Hsu et al. [Hsu, W., Guan, Y., Leshin, L. A., Ushikubo, T. and Wasserburg, G. J. (2006) A late episode of irradiation in the early solar system: Evidence from extinct 36Cl and 26Al in meteorites. Astrophys. J. 640, 525-529], thus indicative of heterogeneous distribution of 36Cl in this CAI. Spallation reactions induced by energetic particles from the young Sun are suggested for the origin of 36Cl, similar to the case of 10Be. While 10Be appears to be present in roughly equal abundance in all studied CAIs, our study indicates the level of 36Cl abundances to be variable so that there seems to be no simple relationship between 10Be and 36Cl. This would be expected if trapped cosmic rays rather

  2. The cosmogenic record of mountain erosion transmitted across a foreland basin: Source-to-sink analysis of in situ10Be, 26Al and 21Ne in sediment of the Po river catchment

    NASA Astrophysics Data System (ADS)

    Wittmann, Hella; Malusà, Marco G.; Resentini, Alberto; Garzanti, Eduardo; Niedermann, Samuel

    2016-10-01

    We analyze the source-to-sink variations of in situ10Be, 26Al and 21Ne concentrations in modern sediment of the Po river catchment, from Alpine, Apennine, floodplain, and delta samples, in order to investigate how the cosmogenic record of orogenic erosion is transmitted across a fast-subsiding foreland basin. The in situ10Be concentrations in the analyzed samples range from ∼ 0.8 ×104 at /gQTZ to ∼ 6.5 ×104 at /gQTZ. The 10Be-derived denudation rates range from 0.1 to 1.5 mm/yr in the Alpine source areas and from 0.3 to 0.5 mm/yr in the Apenninic source areas. The highest 10Be-derived denudation rates are found in the western Central Alps (1.5 mm/yr). From these data, we constrain a sediment flux leaving the Alpine and the Apenninic source areas (>27 Mt/yr and ca. 5 Mt/yr, respectively) that is notably higher than the estimates of sediment export provided by gauging (∼10 Mt/yr at the Po delta). We observe a high variability in 10Be concentrations and 10Be-derived denudation rates in the source areas. In the Po Plain, little variability is observed, and at the same time, the area-weighed 10Be concentration of (2.29 ± 1.57) ×104 at /gQTZ (±1 SD of the dataset) from both the Alps and the Apennines is poorly modified (by tributary input) in sediment of the Po Plain ((2.68 ± 0.78 , ± 1 SD) ×104 at /gQTZ). The buffering effect of the Po floodplain largely removes scatter in 10Be signals. We test for several potential perturbations of the cosmogenic nuclide record during source to sink transfer in the Po basin. We find that sediment trapping in deep glacial lakes or behind dams does not significantly change the 10Be-mountain record. For example, similar 10Be concentrations are measured upstream and downstream of the postglacial Lake Maggiore, suggesting that denudation rates prior to lake formation were similar to today's. On the scale of the entire basin, the 10Be concentration of basins with major dams is similar to those without major dams. A potential

  3. First Long-Term slip-Rate Along the San Andreas Fault Based on 10Be-26Al Surface Exposure Dating : The Biskra Palms Site, 23 mm/yr for the last 30,000 years.

    NASA Astrophysics Data System (ADS)

    van der Woerd, J.; Klinger, Y.; Sieh, K.; Tapponnier, P.; Ryerson, F.

    2001-12-01

    Slip-rate along the San Andreas fault is known precisely at only two locations : at Wallace Creek, 34 +/- 3 mm/yr for the past 13,500 yrs and at Cajon Creek, 24.5+/- 3 mm/yr for the past 14,500 yrs. When compared to the long-term and far-field plate motion, these rates provide important constraint on how and where strain is accommodated across the plate boundary. Here we present a new determination of the slip-rate along the San Andreas Fault at Biskra Palms, based on 10Be-26Al surface exposure dating. The studied area is located southeast of the San Gorgonio restraining bend, a complex section of the fault which has not produced a large earthquake in historical time. At Biskra Palms, the San Andreas Fault offsets an alluvial fan (T2) about 700 m. Keller et al. (1982) recognized the importance of this site and estimated the age of the offset fan surfaces based on degree of soil development between 20 and 70 kyrs, providing a very loosely constraint slip-rate between 10 and 35 mm/yr. We have analyzed 21 quartz rich cobbles from the surface of the fan, upstream, downstream and within the fault zone. 10Be and 26Al measurements yield consistent results implying simple exposure at the surface. 7 samples collected on the T2 fan surface downstream yield an average exposure age of 30.7 +/- 2.1 kyrs. The tight cluster of these ages indicate no or minor pre-exposition during transport in the small catchment upstream. 7 samples from T2 upstream from the fault yield an average exposure age of 29.5 +/- 2.8 kyrs. One additional sample of this surface (38.4+/-3.6 kyrs) is older than the others and may have been pre-exposed before deposition on the fan. 2 samples from a T2 remnant within the fault zone yield an average age of 29.6 +/- 2.6 kyrs. 4 additional samples were collected from two smaller alluvial surfaces (T3 and T4) remnant found only upstream from the fault zone and yield average ages of 33.3 and 27.3 kyrs that are similar to the age of T2. This suggest that these

  4. The French accelerator mass spectrometry facility ASTER after 4 years: Status and recent developments on 36Cl and 129I

    NASA Astrophysics Data System (ADS)

    Arnold, Maurice; Aumaître, Georges; Bourlès, Didier L.; Keddadouche, Karim; Braucher, Régis; Finkel, Robert C.; Nottoli, Emmanuelle; Benedetti, Lucilla; Merchel, Silke

    2013-01-01

    Since the acceptance tests of the French 5 MV accelerator mass spectrometry facility ASTER in 2007, routine measurement conditions for the long-lived radionuclides 10Be and 26Al have been established. Yearly sample throughput as high as over 3300 unknowns has been reached for 10Be in 2010. Cross-contamination for volatile elements has been largely solved by an ion source upgrade allowing 36Cl measurements at ASTER. However, recent long-term tests using 35Cl/37Cl samples with strongly varying ratios have shown that identical targets lead to different 35Cl/37Cl results at the 2-4% level when being measured after a time gap of 24 h while the source is running other samples. Besides time dependent mass fractionation, another likely reason for this effect might be source memory, thus, asking for sophisticated measurement strategies and improved data evaluation and eventually further ion source improvement. Finally, after establishing quality assurance by cross-calibration of secondary in-house 26Al and 41Ca standards and taking part in round-robin exercises of 10Be and 36Cl, a two-step cross-calibration of secondary in-house 129I standards has been performed. The NIST 3231 standard containing 129I/127I at (0.981 ± 0.012) × 10-6 has been used for step-wise dilution with NaI to produce gram-quantities of lower-level standards for every-day use. The resulting material SM-I-9 (129I/127I: ∼1 × 10-9) has been measured vs. AgI produced using minimum chemistry from the two NIST ampoules containing a solution with a nominal ratio 129I/127I of (0.982 ± 0.012) × 10-8. In a second stage, SM-I-10 and SM-I-11 with ratios of ∼1 × 10-10 and ∼1 × 10-11, respectively, have been cross-calibrated against SM-I-9. Individual uncertainties of the traceable secondary standards are 1.3-1.4% (2σ), mainly originating from the given uncertainty of the primary NIST 3231 at the 10-8 level. The cross-contamination for iodine is in the range of 0.4-0.6% within the first 20 h of running

  5. Temporal evolution of (36)Cl abundances in the Great Lakes.

    PubMed

    Poghosyan, Armen; Sturchio, Neil C

    2015-06-01

    The observed (36)Cl isotopic abundance in Great Lakes water decreases from west to east, with the highest (36)Cl/Cl ratio of 1332 × 10(-15) in Lake Superior and the lowest (36)Cl/Cl ratio of 151 × 10(-15) in Lake Erie, whereas the (36)Cl concentration ((36)Cl atoms/L) is lowest in Lake Superior and higher in the other Great Lakes. The (36)Cl concentration in Lake Superior is much higher than expected from normal atmospheric deposition over the basin, consistent with deposition of nuclear bomb-produced (36)Cl during 1952-1964. A conservative mass-balance model constrained by hydrological parameters and available (36)Cl fluence measurements predicts the (36)Cl abundances in the Great Lakes from 1945 to 2015, in excellent agreement with available data for Lakes Superior, Michigan, and Huron, but the model underestimates (36)Cl abundances for Lakes Erie and Ontario. However, assuming that (36)Cl demonstrates non-conservative behavior and is significantly retained in the drainage basins, a model incorporating a delayed input parameter successfully predicts observed (36)Cl concentrations in all of the Great Lakes.

  6. Infiltration at yucca mountain, nevada, traced by 36Cl

    NASA Astrophysics Data System (ADS)

    Norris, A. E.; Wolfsberg, K.; Gifford, S. K.; Bentley, H. W.; Elmore, D.

    1987-11-01

    Measurements of chloride and 36Cl in soils from two locations near Yucca Mountain, Nevada, have been used to trace the infiltration of precipitation in this arid region. The results show that the 36Cl fallout from nuclear-weapons testing formed a well-defined peak at one location, with a maximum 36Cl/Cl ratio 0.5 m below the surface. The structure of the 36Cl bomb pulse at the other location was much more complex, and the quantity of 36Cl in the bomb pulse was < 1% of the 6 × 10 12 atoms {36Cl }/{m 2} in the bomb pulse at the first location. The data indicate hydrologic activity subsequent to the 36Cl bomb-pulse fallout at one location, but none at the other location.

  7. Medical application of 26Al

    NASA Astrophysics Data System (ADS)

    Steinhausen, C.; Gerisch, P.; Heisinger, B.; Hohl, Ch.; Kislinger, G.; Korschinek, G.; Niedermayer, M.; Nolte, E.; Dumitru, M.; Alvarez-Brückmann, M.; Schneider, M.; Ittel, T. H.

    1996-06-01

    Accelerator mass spectrometry (AMS) measurements with 26Al as tracer were performed in order to study the aluminium metabolism and anomalies in the human body and in rats. In particular, the differences between healthy volunteers and patients with renal failure were investigated. The obtained data points of 26Al in blood and urine were described by an open compartment model with three peripheral compartments. It was found that the minimum of peripheral compartments needed to describe 26Al concentrations in blood and urine over a time period of three years is at least three.

  8. Infiltration at Yucca Mountain, Nevada, traced by {sup 36}Cl

    SciTech Connect

    Norris, A.E.; Wolfsberg, K.; Gifford, S.K.; Bentley, H.W.; Elmore, D.

    1987-04-01

    Measurements of chloride and {sup 36}Cl in soils from two locations near Yucca Mountain, Nevada, have been used to trace the infiltration of precipitation in this arid region. The results show that the {sup 36}Cl fallout from nuclear weapons testing formed a well-defined peak at one location, with a maximum 0.5m below the surface. The structure of the {sup 36}Cl bomb pulse at the other location was much more complex, and quantity of {sup 36}Cl in the bomb pulse was <1% of the 6 x 10{sup 12} atoms {sup 36}Cl/m{sup 2} in the bomb pulse at the first location. The data indicate hydrologic activity subsequent to the {sup 36}Cl bomb pulse fallout at one location, but none at the other location. 11 refs.

  9. Detection of 36Cl with accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    Jiang, Songsheng; Ma, Tiejung; Jiang, Shan; Yang, Bingfan; Wang, Xun; Huang, Qi

    1989-12-01

    An accelerator mass spectrometry (AMS) system based on the HI-13 tandem accelerator at the Institute of Atomic Energy (IAE) is described, and the first detection of 36Cl with our AMS system is reported. The electrostatic deflector completely rejects isotopic background, 35Cl and 37Cl. The ioinzation chamber distinguishs 36Cl from isobaric background, 36S. The measurement of 36Cl with two samples is presented.

  10. Comparison of 36Cl and 3He measurements in glacial surfaces on the tropical Altiplano (Cerro Tunupa volcano, 20°S)

    NASA Astrophysics Data System (ADS)

    Schimmelpfennig, Irene; Blard, Pierre-Henri; Lavé, Jérôme; Benedetti, Lucilla; Aster Team

    2016-04-01

    The combination of two or more cosmogenic nuclides measured in the same rock samples allow complex landscape exposure histories to be quantified, due to the nuclide-specific production and decay rates. In supposedly simple exposure scenarios, such as moraine chronologies, the use of more than one nuclide can also help identify outliers caused by geomorphological bias (e.g. "inheritance") or analytical problems (e.g. nuclide loss or contamination during chemical extraction). The two cosmogenic in situ nuclides 3He and 36Cl are potentially very useful to be simultaneously measured in quartz-lacking lithologies, but their application is more challenging than that of combined 10Be and 26Al measurements, which are routinely employed in quartz-bearing rocks. This is, amongst other things, because the production of 3He and 36Cl depend on various compositional factors. Therefore, 3He and 36Cl have rarely been measured in the same samples so far. Here, we present 36Cl measurements in plagioclases extracted from four moraine boulders and one roche moutonnée on the southern flank of Cerro Tunupa volcano, located in the tropical Bolivian Andes (3800-4500 m, 20°S). In pyroxenes of these samples, 3He has previously been measured to gain insights into the local deglaciation history and climate conditions about 15 kyr ago during the Lake Tauca highstand (Blard et al., 2009, 2013). The ages calculated from the measured 3He and 36Cl concentrations of the 5 samples range from 12 kyr to 180 kyr and are generally in good agreement. The good age agreement of a boulder surface (TU-1C) that is significantly older than the other boulder ages from this moraine confirm the suspicion, that it was exposed to cosmic radiation previous to its last deposition (Blard et al., 2009, 2013). In contrast, the 36Cl age of the roche moutonnée surface (TU2) is significantly younger than the corresponding 3He age, but fits well with the adjacent moraine mean age. It thus arises the question if the 3He

  11. {sup 36}Cl bomb fallout at mid latitudes

    SciTech Connect

    Synal, H.A.; Beer, J.; Gaeggeler, H.

    1995-12-01

    Large amounts of {sup 36}Cl have been produced during the atmospheric test of nuclear weapons in the late fifties and early sixties. During this time the {sup 36}Cl fallout was about three orders of magnitudes larger than during previous times. The well defined {sup 36}Cl pulse has a great potential for hydrological investigations, especially as a tracer for groundwater studies. Detailed measurements of bomb produced {sup 36}Cl were carried out earlier on ice cores from Dye-3 (Greenland). To adopt the {sup 36}Cl pulse measured in Greenland as an input function to other locations its latitude dependence has to be known. So far, atmospheric transport models and the measured distribution of {sup 90}Sr and {sup 137}Cs fallout are used to estimate the latitude dependence of meteoric and bomb produced {sup 36}Cl fallout. In this contribution, {sup 36}Cl measurements on an ice core from an Alpine Glacier (Fiescher Horn, Switzerland) are presented. The results are compared with earlier measurements from a Greenland ice core and implications for the global {sup 36}Cl transport are discussed.

  12. Atmospheric transport of bomb-produced 36Cl

    NASA Astrophysics Data System (ADS)

    Synal, H.-A.; Beer, J.; Bonani, G.; Suter, M.; Wölfli, W.

    1990-12-01

    36Cl measurements have been made in an arctic ice core drilled near the Dye-3 site (65°11'N, 43°50'W). The samples analyzed cover the period between 1945 and 1985 with annual resolution. Due to the release of 36Cl to the atmosphere from nuclear bomb tests, the data shown a peak in the late fifties with 36Cl fallout rates about three orders of magnitude higher than expected from cosmic ray production. The time resolution is now precise enough to resolve the structure of the descending part of the fallout pattern. From the fallout rates obtained, a stratospheric residence time for bomb-produced 36Cl could be derived. A detailed interpretation of the data is done with a four-box atmospheric transport model. The large and well-defined 36Cl bomb pulse provides an excellent tracer for ground water studies.

  13. Determination of 36Cl in nuclear waste from reactor decommissioning.

    PubMed

    Hou, Xiaolin; Ostergaard, Lars Frøsig; Nielsen, Sven P

    2007-04-15

    An analytical method for the determination of 36Cl in nuclear waste such as graphite, heavy concrete, steel, aluminum, and lead was developed. Several methods were investigated for decomposing the samples. AgCl precipitation was used to separate 36Cl from the matrix elements, followed by ion-exchange chromatography to remove interfering radionuclides. The purified 36Cl was then measured by liquid scintillation counting. The chemical yield of chlorine, as measured by ICPMS, is above 70% and the decontamination factors for all interfering radionuclides are greater than 10(6). The detection limit of this analytical method for 36Cl is 14 mBq. The method has been used to determine 36Cl in heavy concrete, aluminum, and graphite from the Danish DR-2 research reactor.

  14. Determination of 36Cl in nuclear waste from reactor decommissioning.

    PubMed

    Hou, Xiaolin; Ostergaard, Lars Frøsig; Nielsen, Sven P

    2007-04-15

    An analytical method for the determination of 36Cl in nuclear waste such as graphite, heavy concrete, steel, aluminum, and lead was developed. Several methods were investigated for decomposing the samples. AgCl precipitation was used to separate 36Cl from the matrix elements, followed by ion-exchange chromatography to remove interfering radionuclides. The purified 36Cl was then measured by liquid scintillation counting. The chemical yield of chlorine, as measured by ICPMS, is above 70% and the decontamination factors for all interfering radionuclides are greater than 10(6). The detection limit of this analytical method for 36Cl is 14 mBq. The method has been used to determine 36Cl in heavy concrete, aluminum, and graphite from the Danish DR-2 research reactor. PMID:17375901

  15. High (36)Cl/Cl ratios in Chernobyl groundwater.

    PubMed

    Roux, Céline; Le Gal La Salle, Corinne; Simonucci, Caroline; Van Meir, Nathalie; Fifield, L Keith; Diez, Olivier; Bassot, Sylvain; Simler, Roland; Bugai, Dmitri; Kashparov, Valery; Lancelot, Joël

    2014-12-01

    After the explosion of the Chernobyl Nuclear Power Plant in April 1986, contaminated material was buried in shallow trenches within the exclusion zone. A (90)Sr plume was evidenced downgradient of one of these trenches, trench T22. Due to its conservative properties, (36)Cl is investigated here as a potential tracer to determine the maximal extent of the contamination plume from the trench in groundwater. (36)Cl/Cl ratios measured in groundwater, trench soil water and leaf leachates are 1-5 orders of magnitude higher than the theoretical natural (36)Cl/Cl ratio. This contamination occurred after the Chernobyl explosion and currently persists. Trench T22 acts as an obvious modern point source of (36)Cl, however other sources have to be involved to explain such contamination. (36)Cl contamination of groundwater can be explained by dilution of trench soil water by uncontaminated water (rainwater or deep groundwater). With a plume extending further than that of (90)Sr, radionuclide which is impacted by retention and decay processes, (36)Cl can be considered as a suitable tracer of contamination from the trench in groundwater provided that modern release processes of (36)Cl from trench soil are better characterized. PMID:25128774

  16. High (36)Cl/Cl ratios in Chernobyl groundwater.

    PubMed

    Roux, Céline; Le Gal La Salle, Corinne; Simonucci, Caroline; Van Meir, Nathalie; Fifield, L Keith; Diez, Olivier; Bassot, Sylvain; Simler, Roland; Bugai, Dmitri; Kashparov, Valery; Lancelot, Joël

    2014-12-01

    After the explosion of the Chernobyl Nuclear Power Plant in April 1986, contaminated material was buried in shallow trenches within the exclusion zone. A (90)Sr plume was evidenced downgradient of one of these trenches, trench T22. Due to its conservative properties, (36)Cl is investigated here as a potential tracer to determine the maximal extent of the contamination plume from the trench in groundwater. (36)Cl/Cl ratios measured in groundwater, trench soil water and leaf leachates are 1-5 orders of magnitude higher than the theoretical natural (36)Cl/Cl ratio. This contamination occurred after the Chernobyl explosion and currently persists. Trench T22 acts as an obvious modern point source of (36)Cl, however other sources have to be involved to explain such contamination. (36)Cl contamination of groundwater can be explained by dilution of trench soil water by uncontaminated water (rainwater or deep groundwater). With a plume extending further than that of (90)Sr, radionuclide which is impacted by retention and decay processes, (36)Cl can be considered as a suitable tracer of contamination from the trench in groundwater provided that modern release processes of (36)Cl from trench soil are better characterized.

  17. Distribution and Origin of 36Cl In Allende CAIs

    SciTech Connect

    Matzel, J P; Jacobsen, B; Hutcheon, I D; Krot, A N; Nagashima, K; Yin, Q; Ramon, E C; Weber, P; Wasserburg, G J

    2009-12-11

    The abundance of short-lived radionuclides (SLRs) in early solar system materials provide key information about their nucleosynthetic origin and can constrain the timing of early solar system events. Excesses of {sup 36}S ({sup 36}S*) correlated with {sup 35}Cl/{sup 34}S ratios provide direct evidence for in situ decay of {sup 36}Cl ({tau}{sub 1/2} {approx} 0.3 Ma) and have been reported in sodalite (Na{sub 8}Al{sub 6}Si{sub 6}O{sub 24}Cl{sub 2}) and wadalite (Ca{sub 6}Al{sub 5}Si{sub 2}O{sub 16}Cl{sub 3}) in CAIs and chondrules from the Allende and Ningqiang CV carbonaceous chondrites. While previous studies demonstrate unequivocally that {sup 36}Cl was extant in the early solar system, no consensus on the origin or initial abundance of {sup 36}Cl has emerged. Understanding the origin of {sup 36}Cl, as well as the reported variation in the initial {sup 36}Cl/{sup 35}Cl ratio, requires addressing when, where and how chlorine was incorporated into CAIs and chondrules. These factors are key to distinguishing between stellar nucleosynthesis or energetic particle irradiation for the origin of {sup 36}Cl. Wadalite is a chlorine-rich secondary mineral with structural and chemical affinities to grossular. The high chlorine ({approx}12 wt%) and very low sulfur content (<<0.01 wt%) make wadalite ideal for studies of the {sup 36}Cl-{sup 36}S system. Wadalite is present in Allende CAIs exclusively in the interior regions either in veins crosscutting melilite or in zones between melilite and anorthite associated with intergrowths of grossular, monticellite, and wollastonite. Wadalite and sodalite most likely resulted from open-system alteration of primary minerals with a chlorine-rich fluid phase. We recently reported large {sup 36}S* correlated with {sup 35}Cl/{sup 34}S in wadalite in Allende Type B CAI AJEF, yielding a ({sup 36}Cl/{sup 35}Cl){sub 0} ratio of (1.7 {+-} 0.3) x 10{sup -5}. This value is the highest reported {sup 36}Cl/{sup 35}Cl ratio and is {approx}5 times

  18. Measurement campaign for astrophysically relevant 36Cl production cross sections

    NASA Astrophysics Data System (ADS)

    Anderson, Tyler; Skulski, Michael; Ostdiek, Karen; Lu, Wenting; Beard, Mary; Collon, Philippe

    2015-10-01

    The short-lived radionuclide 36Cl (t1/2 = 0.301 Ma) is known to have existed in the Early Solar System (ESS), and evaluating its production sources can lead to better understanding of the processes taking place in ESS formation and their timescales. The x-wind production model is used to explain 36Cl production via solar energetic particles from the young Sun, but is lacking empirical data for many relevant reactions. Bowers et al. (2013) measured the cross section of 33S(α,p)36Cl at various energies in the range of 0.70-2.42 MeV/A, and found them to be systematically under predicted by statistical Hauser-Feshbach model codes TALYS and NON-SMOKER, highlighting the need for more empirical data for these cross sections. A recent paper by Mohr (2013) called these results in to question, prompting the re-measurement of the cross section for 33S(α,p)36Cl at new energies in the same energy range as Bowers et al. This talk will also discuss two further planned measurements of cross sections suggested by Bowers et al. to be the next most significant in 36Cl production.

  19. Survey on Cosmogenic 26Al in Lewis Cliff Meteorites

    NASA Astrophysics Data System (ADS)

    Welten, K. C.; Alderliesten, C.; Lindner, L.

    1992-07-01

    levels of 56 +- 7 and 60 +- 7 for H and L chondrites, respectively [3], range up to 800 ka with an average of about 290 ka. Altogether this may indicate that the Lewis Cliff blue-ice region is a relatively old meteorite stranding area. This is supported by preliminary conclusions based on ^36Cl, measured in 8 Lewis Cliff meteorites [4]. However, it is likely that some of our terrestrial ages have been overestimated due to (i) lower ^26Al saturation values for meteorites with preatmospheric radii less than 20 cm [3] and (ii) low exposure ages, resulting in initial ^26Al levels below 90-95% of the saturation level. These effects make individual terrestrial age determinations solely based on ^26Al content speculative as long as additional cosmogenic nuclide data are lacking. Dramatic changes in the overall picture are not expected, because (i) we have measured relatively large samples with an average recovered weight of about 500 g (one 11-kg sample excluded) and (ii) anomalously low exposure ages occur in about only 5% of the cases [5,6]. Possible correlations between terrestrial age and place of find will be discussed. UNUSUAL EXPOSURE HISTORIES: We excluded samples with extremely low NTL (<1 krad) from the above discussion, because these may have been exposed to high SCR-fluxes due to smallperihelia orbits (<0.7 A.U.) [7]. This hypothesis is supported by LEW 87169 and 87143, which have extremely low NTL-values in combination with high ^26Al contents. PAIRING CRITERIA: In order to impose additional constraints on pairing possibilities we critically used--besides classification, location of find and TL-properties--the cosmogenic ^26Al and also the natural ^40K content of ordinary chondrites. As an example we will show that the 15 measured Lewis Cliff L6 chondrites are representing at least 10 separate falls. Acknowledgements. This work was performed with financial support from the "Nederlandse Organisatie voor Wetenschappelijk Onderzoek" (NWO). References: 1. Komura K. et

  20. Survey on Cosmogenic 26Al in Lewis Cliff Meteorites

    NASA Astrophysics Data System (ADS)

    Welten, K. C.; Alderliesten, C.; Lindner, L.

    1992-07-01

    levels of 56 +- 7 and 60 +- 7 for H and L chondrites, respectively [3], range up to 800 ka with an average of about 290 ka. Altogether this may indicate that the Lewis Cliff blue-ice region is a relatively old meteorite stranding area. This is supported by preliminary conclusions based on ^36Cl, measured in 8 Lewis Cliff meteorites [4]. However, it is likely that some of our terrestrial ages have been overestimated due to (i) lower ^26Al saturation values for meteorites with preatmospheric radii less than 20 cm [3] and (ii) low exposure ages, resulting in initial ^26Al levels below 90-95% of the saturation level. These effects make individual terrestrial age determinations solely based on ^26Al content speculative as long as additional cosmogenic nuclide data are lacking. Dramatic changes in the overall picture are not expected, because (i) we have measured relatively large samples with an average recovered weight of about 500 g (one 11-kg sample excluded) and (ii) anomalously low exposure ages occur in about only 5% of the cases [5,6]. Possible correlations between terrestrial age and place of find will be discussed. UNUSUAL EXPOSURE HISTORIES: We excluded samples with extremely low NTL (<1 krad) from the above discussion, because these may have been exposed to high SCR-fluxes due to smallperihelia orbits (<0.7 A.U.) [7]. This hypothesis is supported by LEW 87169 and 87143, which have extremely low NTL-values in combination with high ^26Al contents. PAIRING CRITERIA: In order to impose additional constraints on pairing possibilities we critically used--besides classification, location of find and TL-properties--the cosmogenic ^26Al and also the natural ^40K content of ordinary chondrites. As an example we will show that the 15 measured Lewis Cliff L6 chondrites are representing at least 10 separate falls. Acknowledgements. This work was performed with financial support from the "Nederlandse Organisatie voor Wetenschappelijk Onderzoek" (NWO). References: 1. Komura K. et

  1. Measurement of 26Al in Antarctic ice with the MALT-AMS system at the University of Tokyo

    NASA Astrophysics Data System (ADS)

    Horiuchi, Kazuho; Matsuzaki, Hiroyuki; Ohta, Aoi; Shibata, Yasuyuki; Motoyama, Hideaki

    2007-06-01

    We have attempted to determine the 26Al concentration of Antarctic ice sampled from the vicinity of the Dome Fuji Research Station using accelerator mass spectrometry (AMS) at MALT (MicroAnalysis Laboratory, Tandem accelerator) of the University of Tokyo. Because the expected concentration of 26Al in ice is very low, our standard procedure for the AMS measurement was re-examined and refined. The observed 26Al concentration ranged between 160 and 210 atoms g-1. The averaged value of the 26Al/10Be ratio from two samples was 1.75 ± 0.19 × 10-3, which agrees well with recently reported values for the meteoric 26Al/10Be ratio from Antarctic ice and air filter residues. This result implies the possibility of future 26Al/10Be dating of old Antarctic ice.

  2. 36Cl-36Ar Exposure Ages of Chondritic Metals

    NASA Astrophysics Data System (ADS)

    Graf, Th.; Caffee, M. W.; Finkel, R. C.; Marti, K.; Nishiizumi, K.; Ponganis, K. V.

    1995-09-01

    Metal separates were prepared to determine ^36Cl-^36Ar exposure ages for six H4 p.m. falls (with reported bulk exposure ages of 4 to 10Ma), for ten H5 a.m. falls (T(sub)e = 4-10 Ma) and for the Acapulco meteorite (T(^36Cl-^36Ar)= 5.7 Ma). This dating method uses production rate ratios P(^36Cl)/P(^36Ar) and is independent of the shielding-sensitive absolute production rates. It is also known that for protons the production rate ratio is rather insensitive to changes in the energy spectrum; the dependence of this ratio for secondary neutrons is at present less understood. First results were already reported [1]. The cosmic-ray-produced ^3He/^38Ar ratios show a bimodal distribution with two clusters at about 15 and about 9 (Fig. 1). About half of the ^3He is produced via ^3H which is known to diffuse in metal at relatively low temperatures. Therefore, Fig. 1 provides evidence for a quasi-continuous loss of ^3H from such metals. If this loss mechanism is due to solar heating, perihelia <1 AU are indicated for these meteorites. Losses are prominent for H5 a.m. falls, but not for H4 p.m. falls. The orbital implications are consistent with those already known from the time-of-fall parameter (p.m. falls / total falls) which was used in the selection of the H4,H5 sample sets [2]. The exposure age histograms of both H groups show the well known clusters at about 7 Ma. The width of the exposure age peaks differ, however, and the collisional break-up event can be further constrained. Except for Nassirah, all members of the H4 p.m. group fall into the range 7.0 +/- 0.3 Ma. Bulk rock ages (8.2-9.3 Ma) [3] as well as the ^36Cl-^36Ar age (8.3 Ma) of Nassirah are higher and may indicate that this meteorite does not belong to the collisional event. We observe a small but systematic difference in calculated exposure ages by the ^36Cl-^36Ar method, when compared with ages obtained by conventional noble gas production rates. This shift (about 10%) does not appear to be dependent on

  3. SPI measurements of Galactic 26Al

    NASA Astrophysics Data System (ADS)

    Diehl, R.; Knödlseder, J.; Lichti, G. G.; Kretschmer, K.; Schanne, S.; Schönfelder, V.; Strong, A. W.; von Kienlin, A.; Weidenspointner, G.; Winkler, C.; Wunderer, C.

    2003-11-01

    The precision measurement of the 1809 keV gamma-ray line from Galactic 26Al is one of the goals of the SPI spectrometer on INTEGRAL with its Ge detector camera. We aim for determination of the detailed shape of this gamma-ray line, and its variation for different source regions along the plane of the Galaxy. Data from the first part of the core program observations of the first mission year have been inspected. A clear detection of the 26Al line at =~ 5-7 sigma significance demonstrates that SPI will deepen 26Al studies. The line intensity is consistent with expectations from previous experiments, and the line appears narrower than the 5.4 keV FWHM reported by GRIS, more consistent with RHESSI's recent value. Only preliminary statements can be made at this time, however, due to the multi-component background underlying the signal at =~ 40 times higher intensity than the signal from Galactic 26Al.

  4. {sup 36}Cl studies of water movements deep within unsaturated tuffs

    SciTech Connect

    Norris, A.E.; Bentley, H.W.; Cheng, S.; Kubik, P.W.; Sharma, P.; Gove, H.E.

    1990-05-01

    Measurements of {sup 36}Cl in cuttings from a borehole that was drilled 387 m into unsaturated tuffs indicate the possible detection of significant radioactive decay of cosmogenic {sup 36}Cl in two of the samples. However, the {sup 36}Cl/Cl ratio was found to vary with the amount of pulverization of the cuttings. Work is in progress to separate the {sup 36}Cl/Cl data into cosmogenic and in situ components. The cosmogenic component will be used to trace very slow water movements through the unsaturated zone. Bomb pulse {sup 36}Cl was observed as deep as 153 m, and this identification is not constrained by the problem with pulverization. This work shows the efficacy of {sup 36}Cl measurements for detecting modern water movements deep in the unsaturated zone. 9 refs., 3 tabs.

  5. Observable Proxies For 26 Al Enhancement

    SciTech Connect

    Fryer, Christopher L; Young, Patrick A; Ellinger, Carola I; Arnett, William D

    2008-01-01

    We consider the cospatial production of elements in supernova explosions to find observationally detectable proxies for enhancement of {sup 26}Al in supernova ejecta and stellar systems. Using four progenitors we explore a range of 1D explosions at different energies and an asymmetric 3D explosion. We find that the most reliable indicator of the presence of {sup 26}Al in unmixed ejecta is a very low S/Si ratio ({approx} 0.05). Production of N in O/S/Si-rich regions is also indicative. The biologically important element P is produced at its highest abundance in the same regions. Proxies should be detectable in supernova ejecta with high spatial resolution multi wavelength observations, but the small absolute abundance of material injected into a proto-planetary disk makes detection unlikely in existing or forming stellar/planetary systems.

  6. Evidence that 26Al Did Not Melt Asteroids

    NASA Astrophysics Data System (ADS)

    Wasson, J. T.

    2016-08-01

    26Al/27Al initial ratios in achondrites are much lower than expected if 26Al was the only heat source responsible for melting the parental materials. Impacts provided a substantial fraction of the heat.

  7. Determination of 36Cl in biological shield concrete using pyrohydrolysis and liquid scintillation counting.

    PubMed

    Itoh, Mitsuo; Watanabe, Kazuo; Hatakeyama, Mutsuo; Tachibana, Mitsuo

    2002-07-01

    A method for the determination of 36Cl in biological shield concrete of nuclear reactors was developed. Cl in the concrete sample was extracted quantitatively by pyrohydrolysis at 900 degrees C and recovered in Na2CO3 solution for subsequent measurement of 36Cl by liquid scintillation counting. WO3 was used as an accelerator in the pyrohydrolysis. The Cl extraction procedure was optimized by investigating experimental conditions with the use of ion chromatography and its recovery was evaluated by the analysis of the geochemical reference samples. The detection limit of 36Cl was 0.02 Bq g(-1) for a sample weight of 2 g. The relative standard deviation was 3-7% for the samples containing 0.5 Bq g(-1) levels of 36Cl. The method was applied to determine 36Cl in biological shield concrete of the Japan Power Demonstration Reactor. PMID:12173658

  8. The Hiroshima thermal-neutron discrepancy for (36)Cl at large distances. Part I: New (36)Cl measurements in granite samples exposed to A-bomb neutrons.

    PubMed

    Huber, Thomas; Rühm, Werner; Kato, Kazuo; Egbert, Stephen D; Kubo, Florian; Lazarev, Vitali; Nolte, Eckehart

    2005-10-01

    The long-lived radioisotope (36)Cl (half-life: 301,000 years) was measured in granite samples exposed to A-bomb neutrons at distances from 94 to 1,591 m from the hypocenter in Hiroshima, by means of accelerator mass spectrometry (AMS). Measured (36)Cl/Cl ratios decrease from 1.6 x 10(-10) close to the hypocenter to about 1-2 x 10(-13), at a distance of 1,300 m from the hypocenter. At this distance and beyond the measured (36)Cl/Cl ratios do not change significantly and scatter around values of 1-2 x 10(-13). These findings suggest that the (36)Cl had been predominantly produced by thermalized neutrons from the A-bomb via neutron capture on stable (35)Cl, at distances from the hypocenter smaller than about 1,200 m. At larger distances, however, confounding processes induced by cosmic rays or neutrons from the decay of uranium and thorium become important. This hypothesis is theoretically and experimentally supported in a consecutive paper. The results are compared to calculations that are based on the most recent dosimetry system DS02. Close to the hypocenter, measured (36)Cl/Cl ratios are lower than those calculated, while they are significantly higher at large distances from the hypocenter. If the contribution of the cosmic rays and of the neutrons from the decay of uranium and thorium in the sample was subtracted, however, no significant deviation from the DS02 calculations was observed, at those distances. Thus, the Hiroshima neutron discrepancy reported in the literature for (36)Cl for samples from large distances from the hypocenter, i.e., higher measured (36)Cl/Cl ratios than predicted by the previous dosimetry system DS86, was not confirmed.

  9. The distribution of meteoric 36Cl/Cl in the United States: A comparison of models

    USGS Publications Warehouse

    Moysey, S.; Davis, S.N.; Zreda, M.; Cecil, L.D.

    2003-01-01

    The natural distribution of 36Cl/Cl in groundwater across the continental United States has recently been reported by Davis et al. (2003). In this paper, the large-scale processes and atmospheric sources of 36Cl and chloride responsible for controlling the observed 36Cl/Cl distribution are discussed. The dominant process that affects 36Cl/Cl in meteoric groundwater at the continental scale is the fallout of stable chloride from the atmosphere, which is mainly derived from oceanic sources. Atmospheric circulation transports marine chloride to the continental interior, where distance from the coast, topography, and wind patterns define the chloride distribution. The only major deviation from this pattern is observed in northern Utah and southern Idaho where it is inferred that a continental source of chloride exists in the Bonneville Salt Flats, Utah. In contrast to previous studies, the atmospheric flux of 36Cl to the land surface was found to be approximately constant over the United States, without a strong correlation between local 36Cl fallout and annual precipitation. However, the correlation between these variables was significantly improved (R 2=0.15 to R 2=0.55) when data from the southeastern USA, which presumably have lower than average atmospheric 36Cl concentrations, were excluded. The total mean flux of 36Cl over the continental United States and total global mean flux of 36Cl are calculated to be 30.5??7.0 and 19.6??4.5 atoms m-2 s-1, respectively. The 36Cl/Cl distribution calculated by Bentley et al. (1996) underestimates the magnitude and variability observed for the measured 36Cl/Cl distribution across the continental United States. The model proposed by Hainsworth (1994) provides the best overall fit to the observed 36Cl/Cl distribution in this study. A process-oriented model by Phillips (2000) generally overestimates 36Cl/Cl in most parts of the country and has several significant local departures from the empirical data.

  10. High temperature pyrolysis to extract 36Cl for Accelerator Mass Spectrometry measurements

    NASA Astrophysics Data System (ADS)

    Cornett, R. J.; Andrews, H. R.; Chant, L.; Chaput, T.; Imahori, Y.; Jirovec, J.; Kramer, S.; Koslowsky, V. T.; Milton, G. M.; Milton, J. C. D.

    1996-10-01

    36Cl and stable Cl were extracted from solids by high temperature pyrolysis and then analyzed by Accelerator Mass Spectrometry (AMS). Cl was quantitatively extracted from rock, ore, vegetation and freshwater sediments in samples weighing from 100 mg to 2 g. 36Cl:Cl activity ratios measured following Cl extraction by pyrolysis agreed with those measured following Cl extraction by acid leaching. The simple pyrolysis extraction has the additional advantages that stable Cl - can be measured on the same sample along with other anions, the 36Cl:Cl ratio can be adjusted by diluting the known Cl - concentration in the collection solution to control the activity of 36Cl in the target and the potential interference of 36S can also be assessed prior to the AMS measurements.

  11. 26Al uptake and accumulation in the rat brain

    NASA Astrophysics Data System (ADS)

    Yumoto, S.; Nagai, H.; Imamura, M.; Matsuzaki, H.; Hayashi, K.; Masuda, A.; Kumazawa, H.; Ohashi, H.; Kobayashi, K.

    1997-03-01

    To investigate the cause of Alzheimer's disease (senile dementia), 26Al incorporation in the rat brain was studied by accelerator mass spectrometry (AMS). When 26Al was injected into healthy rats, a considerable amount of 26Al entered the brain (cerebrum) through the blood-brain barrier 5 days after a single injection, and the brain 26Al level remained almost constant from 5 to 270 days. On the other hand, the level of 26Al in the blood decreased remarkably 75 days after injection. Approximately 89% of the 26Al taken in by the brain cell nuclei bound to chromatin. This study supports the theory that Alzheimer's disease is caused by irreversible accumulation of aluminium (Al) in the brain, and brain cell nuclei.

  12. Cosmogenic {sup 36}Cl accumulation in unstable landforms 2. Simulations and measurements on eroding moraines

    SciTech Connect

    Zreda, M.G.; Phillips, F.M.; Elmore, D.

    1994-11-01

    Cosmogenic {sup 36}Cl ages of boulders from late Pleistocene moraines in Bishop Creek, Sierra Nevada, California, provided valuable details about {sup 36}Cl surface exposure dating and the nature of post depositional processes that modify glacial landforms. The natural variability of the apparent {sup 36}Cl ages among morainal boulders is due to soil erosion and gradual exposure of boulders at the surface. Two mechanisms are responsible for the resulting distributions of the apparent {sup 36}Cl ages. Variability of the initial burial depth among boulders and variability in the chemical composition of boulders from the same depth both result in different {sup 36}Cl ages due to the dependence of the depth production profile on the boulder chemistry. The authors measured cosmogenic {sup 36}Cl in boulders from a late Pleistocene moraine. The distribution of the calculated apparent ages allowed them to calculate the true age of 85 kyr and the erosion rate of 570 g cm{sup -2}. These results are in excellent agreement with independently estimated values of 87 kyr and 600 g cm{sup -2} for the age and erosion depth, respectively. These results indicate that the model satisfactorily simulates effects of erosion processes and can thus aid in surface exposure dating of eroding landforms.

  13. Quality assurance and 36Cl program at SUERC: Implications to landscape evolution research

    NASA Astrophysics Data System (ADS)

    Wilcken, Klaus; Freeman, Stewart; Phillips, Richard; Schnabel, Christoph; Binnie, Steven; Dougans, Andrew; Dunai, Tibor; Cowie, Patience; Roberts, Gerald

    2010-05-01

    In situ-produced cosmogenic nuclei, made by cosmic ray induced nuclear reactions cumulatively on exposed surfaces, are natural chronometers and valuable tools for environmental and geological research. Cosmogenic 36Cl (t1-2=3e5 yr) is dominantly produced in spallation reactions on Ca and K, and via neutron capture on 35Cl, and hence is applicable to a range of lithologies for studying events within the last 1 Myr or so. The different 36Cl production mechanisms result in versatility but also challenging data interpretation when unravelling the measured 36Cl concentrations. The main difficulty in utilising 36Cl for environmental and geological research arises from the stable isobar 36S. However, if high enough ion energies are available, these two isotopes can be separated based upon their different rate of energy loss in matter. This has typically required large (10-15 MV) legacy nuclear physics particle accelerators but recently it has been shown that sufficient separation can be achieved with much lower ion energies than before (~30 MeV); the detector resolution being improved by using uniform thin (~30 nm) Silicon rich Nitride membranes as a detector window to minimise energy losses and peak broadening. As a consequence, measurements can now be done with 5 MV, or even smaller, modern accelerator mass spectrometers utilising gas stripping to produce the highest possible quality beams. Accordingly a new class of commercial purpose-build 5-6 MV 36Cl-capable spectrometers is being deployed around the globe with additional measurement capacity greater than that of the installed base. This should increase accessibility and promote wider and more varied 36Cl use. However, laborious sample preparation chemistry and production rate uncertainties remain difficulties. An example 36Cl programme utilising the 5 MV accelerator mass spectrometer at SUERC will be presented. Our internal quality assurance program shows that no external uncertainty beyond 3% counting statistics is

  14. A study of 36Cl production in the early Solar System

    NASA Astrophysics Data System (ADS)

    Bowers, Matthew R.

    Short-lived radionuclides (SLRs) with lifetimes tau < 100 Ma are known to have been extant when the Solar System formed 4.568 billion years ago from meteoritic studies of their decay products. Identifying the origins of SLRs can provide insight into the origins and timescales of our Solar System and the processes that shaped it. There are two proposed production scenarios for the origins of SLRs with tau < 5 Ma. Freshly synthesized material could be incorporated in the Solar System by a nearby stellar source (e.g., supernova, AGB star, Wolf-Rayet star), or SLRs could have also been produced by the bombardment of gas and dust by solar energetic particles (SEP) emitted by our young Sun. The origin of extinct 36Cl (t1/2 = 0.301 Ma) in the early Solar System is thought to have been produced by local particle irradiation. However the models that attempt to recreate the production of 36Cl in the early Solar System lack experimental data for the nuclear reactions considered. The first measurement of the 33S(alpha,p) 36Cl reaction, an important reaction in the production of 36Cl , was performed. The cross section measurement was performed by bombarding a target and collecting the recoiled 36Cl atoms produced in the reaction, chemically processing the samples, and measuring the 36Cl/Cl concentration of the samples with accelerator mass spectrometry (AMS). The cross section was measured at six energies that ranged from 0.70 up to 2.42 MeV/A, within the SEP energy spectrum. The experimental results were found to be systematically higher than the predicted cross sections. However, the deviations lead to < 7 % increase in total production of 36Cl under the x-wind model. From the experimental measurement and a study of the other reactions' contributions to 36Cl production, 36Cl could have been produced close to the protoSun by reactions on Ca targets using the x-wind model, or in a late-stage irradiation event on a volatile-rich reservoir by 3He and alpha reactions on S targets.

  15. Further Exploration of the 33S(α,p)36Cl Reaction Cross Section

    NASA Astrophysics Data System (ADS)

    Skulski, Michael; Anderson, Tyler; Beard, Mary; Collon, Philippe; Lu, Wenting; Ostdiek, Karen

    2015-10-01

    Short-lived radionuclides (SLRs) are extant from the Early Solar System (ESS) and useful for dating products of ESS processes. The SLR 36Cl was potentially produced by solar energetic particles incident on gas and dust in the protoplanetary disk. Measurement of the cross section of the reaction 33S(α,p)36Cl, which contributes significantly to the abundance of 36Cl, is an important input in solar irradiation models regarding the determination of elemental abundances, and is thus of great interest. In a previous measurement performed by Bowers et al. (2013), the cross section of this reaction was studied using a combination of activation of a 4He gas cell and analyzing the produced 36Cl via Accelerator Mass Spectrometry (AMS) over an energy range of 0.7 - 2.42 MeV/A. The result of this measurement was a significantly higher yield of 36Cl than predicted by Hauser-Feshbach cross section calculations. In light of the paper by Mohr (2013), the same activation was repeated at the University of Notre Dame at intermediate energies to study the cross section further, using the same combination of activation and AMS. The results of this measurement will be presented.

  16. Study of nuclear reactions producing 36Cl by micro-AMS

    NASA Astrophysics Data System (ADS)

    Luís, H.; Jesus, A. P.; Fonseca, M.; Cruz, J.; Galaviz, D.; Franco, N.; Alves, E.

    2016-01-01

    36Cl is one of several short to medium lived isotopes (as compared to the earth age) whose abundances at the earlier solar system may help to clarify its formation process. There are two generally accepted possible models for the production of this radionuclide: it originated from the ejecta of a nearby supernova (where 36Cl was most probably produced in the s-process by neutron irradiation of 35Cl) and/or it was produced by in-situ irradiation of nebular dust by energetic particles (mostly, p, a, 3He -X-wind irradiation model). The objective of the present work is to measure the cross section of the 37Cl(p,d)36Cl and 35Cl(d,p)36Cl nuclear reactions, by measuring the 36Cl content of AgCl samples (previously bombarded with high energy protons and deuterons) with AMS, taking advantage of the very low detection limits of this technique for chlorine measurements. For that, the micro-AMS system of the LF1/ITN laboratory had to be optimized for chlorine measurements, as to our knowledge this type of measurements had never been performed in such a system (AMS with micro-beam). Here are presented the first results of these developments, namely the tests in terms of precision and reproducibility that were done by comparing AgCl blanks irradiated at the Portuguese National Reactor with standards produced by the dilution of the NIST SRM 4943 standard material.

  17. The sup 36 Cl ages of the brines in the Magadi-Natron basin, east Africa

    SciTech Connect

    Kaufman, A.; Margaritz, M.A.; Hollos, G. ); Paul, M.; Boaretto, E. ); Hillaire-Marcel, C. ); Taieb, M. )

    1990-10-01

    The depression in the East African Rift which includes both Lake Magadi and Lake Natron forms a closed basin within which almost all the dissolved chloride originates in precipitation, since there is no important source of very ancient sedimentary chloride. This provides an ideal setting for the evaluation of the {sup 36}Cl methodology as a geochemical and hydrological tracer. The main source of recent water, as represented by the most dilute samples measured, is characterized by a {sup 36}Cl/Cl ratio of 2.5 {times} 10{sup {minus}14}, in agreement with the calculated value expected in precipitation. Surface evaporation increases the chlorinity of the local freshwater inflow by about a factor of 110 without changing the isotopic ratio, indicating that little chloride enters the system in the form of sediment leachate. A second type of brine found in the basin occurs in a hot deep groundwater reservoir and is characterized by lower {sup 36}Cl/Cl ratios (<1.2 {times} 10{sup {minus}14}). By comparing this value with the 2.5 {times} 10{sup {minus}14} in recent recharge, one obtains an approximate salt accumulation age of 760 Ka which is consistent with thee time of the first appearance of the lake. These older brines also have lower {sup 18}O and {sup 2}H values which indicate that they were recharged during a climatically different era. The {sup 36}Cl/Cl ratios in the inflowing waters and in the accumulated brine, together with the known age of the Lake Magadi basin, may be used to estimate the importance of the hypogene and epigene, as opposed to the meteoric, mode of {sup 36}Cl production. Such a calculation shows that the hypogene and epigene processes together contribute less than 6% of the total {sup 36}Cl present in the lake.

  18. Probing Galactic 26Al with Exotic Ion Beams

    SciTech Connect

    Chen, Alan A.

    2006-07-12

    The goal of understanding the production of galactic 26Al brings together progress in nuclear astrophysics from observations, theory, meteoritics, and laboratory experiments. In the case of experimental work, nuclear reactions involving unstable isotopes are being studied to elucidate the production of 26Al in stellar explosive nucleosynthesis. We discuss a direct measurement of the 26Al(p,{gamma})27Si reaction with the DRAGON collaboration at TRIUMF, and a measurement of 25Al+p elastic scattering with the CRIB (CNS-U.Tokyo) collaboration, toward constraining the 25Al(p,{gamma})26Si reaction.

  19. Probing Galactic 26Al with Exotic Ion Beams

    NASA Astrophysics Data System (ADS)

    Chen, Alan A.

    2006-07-01

    The goal of understanding the production of galactic 26Al brings together progress in nuclear astrophysics from observations, theory, meteoritics, and laboratory experiments. In the case of experimental work, nuclear reactions involving unstable isotopes are being studied to elucidate the production of 26Al in stellar explosive nucleosynthesis. We discuss a direct measurement of the 26Al(p,γ)27Si reaction with the DRAGON collaboration at TRIUMF, and a measurement of 25Al+p elastic scattering with the CRIB (CNS-U.Tokyo) collaboration, toward constraining the 25Al(p,γ)26Si reaction.

  20. Production rates of 36Cl in basalts from the calibration site of Fuerteventura, Canary Islands

    NASA Astrophysics Data System (ADS)

    Mai, K.

    2009-09-01

    Age determination based on cosmogenic nuclides is an important tool to investigate landscape development and age relations of geologically very young materials. The aim of this study is to contribute data to establish age determination of the basis of cosmogenic 36Cl production as a generally reliable method. 36Cl is a radionuclide that is in situ produced by cosmic radiation at the earth surface. It is formed by spallation from Ca, K, Ti, and Fe, by thermal neutron capture in 35Cl, and by muogenic production from Ca and K. The concentration of the cosmogenic nuclide provides a measure of the exposure age of the surface, but also of the exposure history which may include periods of burial or erosion. Several factors such as the geographic position of the site, the topographic shielding of the surrounding hillside and the sample thickness or sampling depth influence the effective amount of radiation hitting the surface and are taken into account by applying appropriate scaling factors. Basalt samples from the mid-latitude, low altitude calibration site of Fuerteventura, Canary Islands were collected and the production rates of 36Cl were determined. Geologically young samples covering an age range of approximately 50 to 400 ka could be collected from a number of flows, which suit the time span that can be covered with 36Cl age determination. The age was independently determined with the 40Ar/39Ar method. From nine lava flows 7 or 8 samples were collected whose surface structures indicated as little erosion as possible. ICP and XRF measurements proved that the basalts were very similar in chemical composition. The preparation of the AMS samples followed generally the procedure established by Stone et al. (1996b). The measurements were performed at the AMS facility at the University of Utrecht. From the results of the measurements total chlorine concentrations the amount of 36Cl, and the production rates were deduced. The high variability of the production rates for

  1. Radiocarbon dating and the 36Cl/Cl evolution of three Great Artesian Basin wells at Dalhousie, South Australia

    NASA Astrophysics Data System (ADS)

    Abu Risha, Usama A.

    2016-06-01

    The use of 14C (half-life = 5,730 years) in modeling the evolution of the 36Cl/Cl ratios in groundwater is reported for the first time. The complexity of the Cl-36Cl system due to the occurrence of different Cl and 36Cl sources and the difficulty of the determination of the initial groundwater 36Cl/Cl ratios have raised concerns about the reliability of using 36Cl (half-life = 301 thousand years, a) as a groundwater-dating tool. This work uses groundwater 14C age as a calibrating parameter of the Cl-36Cl/Cl decay-mixing models of three wells from the southwestern Great Artesian Basin (GAB), Australia. It aims to allow for the different sources of Cl and 36Cl in the southwestern GAB aquifer. The results show that the initial Cl concentrations range from 245 to 320 mg/l and stable Cl is added to groundwater along flowpaths at rates ranging from 1.4 to 3.5 mg/l/ka. The 36Cl content of the groundwater is assumed to be completely of atmospheric origin. The samples have different Cl-36Cl/Cl mixing-decay models reflecting recharge under different conditions as well as the heterogeneity of the aquifer.

  2. Distribution and chemical fate of 36Cl-chlorine dioxide gas during the fumigation of tomatoes and cantaloupe

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The distribution and chemical fate of 36Cl-ClO2 gas subsequent to fumigation of tomatoes or cantaloupe was investigated as was major factors that affect the formation of chloroxyanion byproducts. Approximately 22% of the generated 36Cl-ClO2 was present on fumigated tomatoes after a 2-hour exposure t...

  3. Measurement of cosmogenic /sup 36/Cl/Cl in young volcanic rocks: An application of accelerator mass spectrometry in geochronology

    SciTech Connect

    Leavy, B.D.; Phillips, F.M.; Elmore, D.; Kubik, P.W.

    1987-01-01

    We have measured /sup 36/Cl/Cl ratios in a number of young volcanic rocks in order to test the feasibility of using /sup 36/Cl buildup as a geochronometer for materials less than about 700,000 years old. All of the analyzed rocks have been dated independently using K-Ar or other radiometric dating methods and have exposure histories that are known or can be reasonably assumed. Measured /sup 36/Cl/Cl ratios in these rocks are in good agreement with the calculated in-situ /sup 36/Cl buildup curve. These analyses indicate that AMS measurement of /sup 36/Cl buildup in young rocks is a potentially powerful new method for dating materials that had previously been undatable, and as such will have broad applications in volcanology, tectonics, geophysics, and Quaternary research.

  4. Observation of 23 Supernovae that Exploded <300 pc from Earth During the Past 300 kyr in the Radiocarbon and 10Be Cosmogenic Isotope Record

    NASA Astrophysics Data System (ADS)

    Firestone, R. B.

    2014-12-01

    The global excess radiocarbon abundance record for the past 50 kyr can be entirely explained by the explosion of four supernovae 44, 37, 32, and 22 kyr ago less than 250 pc from Earth. Each supernova left a nearly identical signature beginning with a sudden increase at the time of the explosion, followed by a hiatus of 1500 years, and continuing with a sustained, 2000 year increase in radiocarbon from gamma rays produced by diffusive shock in the supernova remnant. For the past 18 kyr excess radiocarbon from SN22kyrBP, identified as the Vela supernova, has decayed with the 5700 year half-life of 14C. The absolute scale for radiocarbon abundance has been determined from the decay curve as Δ14C=5±2% in 1950. Small oscillations in the decay curve are shown to coincide with variations in Earth's Virtual Axial Dipole Moment (VADM). SN44kyrBP exploded approximately 110 pc from Earth doubling the radiocarbon abundance. These supernovae are confirmed in the 10Be, 26Al, 36Cl and nitrate geological records. An additional 19 supernovae are observed 50-300 kyr ago in the 10Be record. Using the Earth as a calorimeter I have determined that approximated 2×1049 ergs were released at the time of each supernova explosion and 1049-50 ergs afterwards, consistent with theoretical predictions. The background rate of radiocarbon productions from more distant sources was determined as 1.61 atoms/cm2s at the top of the atmosphere. Although little danger to life on Earth is expected from these supernovae, each of the recent events were shown to correlate with concurrent global warming of 3-4°C.

  5. 36Cl: A tracer in groundwater in the aquia formation of Southern Maryland

    USGS Publications Warehouse

    Purdy, C.B.; Mignerey, A.C.; Helz, G.R.; Drummond, D.D.; Kubik, P.W.; Elmore, D.; Hemmick, T.

    1987-01-01

    The Aquia Formation (Paleocene) of Southern Maryland, a marine unit consisting predominantly of quartz sands, but containing 20-40% glauconite, represents one of the many productive, heavily pumped aquifers of the Southeastern Coastal Plain. An unusually high 36Cl activity ( ~ 15 ?? modem water) measured in an outcrop sample is interpreted as a result of the bomb pulse input. About 25 km downdip from the recharge area, a minimum in total chloride concentration occurs. This minimum is thought to correlate with the latest low-stand of sea-level, and thus to provide time information which is in general agreement with ages calculated from hydrodynamic data. However, significant increases in the 36Cl concentrations are observed along the flow path which may be due to ion filtration or to leakage of modem, bomb-contaminated water into the Aquia aquifer. ?? 1987.

  6. Long-term measurements of 36Cl to investigate potential solar influence on the decay rate

    NASA Astrophysics Data System (ADS)

    Kossert, Karsten; Nähle, Ole J.

    2014-03-01

    Recently, Jenkins et al. [6] reported on fluctuations in the detected decay events of 36Cl which were measured with a Geiger-Müller counter. Experimental data of 32Si measured by means of an end-window gas-flow proportional counter at the Brookhaven National Laboratory show similar periodicity, albeit a different amplitude. Jenkins et al. interpret the fluctuations as evidence of solar influence on the decay rates of beta-decaying radionuclides.

  7. 36Cl ages of deep saline groundwater in coastal sedimentary areas in Japan

    NASA Astrophysics Data System (ADS)

    Tosaki, Y.; Morikawa, N.; Kazahaya, K.; Yasuhara, M.; Takahashi, H.; Horiguchi, K.; Sato, T.; Takahashi, M.; Inamura, A.

    2015-12-01

    Climate-induced sea-level fluctuations can have impacts on groundwater flow regimes, especially in coastal areas. A sea level decline leads to a seaward movement of the discharge area of regional groundwater flow system, accompanying increased hydraulic heads in aquifers that enhances deeper groundwater flow. It also brings drastic changes in shorelines and associated topography of coastal areas, which potentially affect groundwater flow regimes. Therefore, an assessment of the influence of sea-level change on groundwater system is especially important. In this study, we focus on several sedimentary basins in Japan, including the Ishikari Plain, the Tsugaru Plain, and the Kanto Plain. Saline groundwater samples were collected from deep boreholes located over the plains, and analyzed for 36Cl/Cl ratios. Several rock samples taken from each area were measured for whole-rock chemical compositions to determine the secular equilibrium 36Cl/Cl ratios in deep aquifers. The obtained 36Cl ages are generally greater than 100 kyr, and tend to become older in inland areas. These age distribution patterns for each area are compared with the locations of past shorelines. The results may show some factors, including topography and geology, which may control the influence of sea-level change on groundwater systems in coastal sedimentary areas. Acknowledgement: Main part of this research project has been conducted as the regulatory supporting research funded by the Secretariat of the Nuclear Regulation Authority, Japan.

  8. Cosmogenic {sup 36}Cl accumulation in unstable landforms 1. Effects of the thermal neutron distribution

    SciTech Connect

    Liu, B.; Phillips, F.M.; Stone, W.D.; Fabryka-Martin, J.T.; Fowler, M.M.

    1994-11-01

    Cosmogenic nuclides produced in situ within minerals at the surface of the Earth are proving to be an effective means of assessing geomorphic histories. The use of multiple cosmogenic nuclides permits both exposure times and erosion rates to be determined. However, if two nuclides are produced only by spallation reactions, the systematic differences in their accumulation rates depend only on the differences in their production rates and half-lives. The relatively small differences that result require a high degree of analytical precision to yield useful results. In contrast to other spallogenic nuclides, {sup 36}Cl is also produced by low-energy neutron, absorption, which creates a different pattern of production as a function of depth. We have measured the thermal flux with depth in a concrete block using {sup 3}He-filled neutron detectors. The measured thermal neutron profile agrees well with predictions from a simple diffusion-based thermal neutron distribution model. Calculations of {sup 36}Cl production using the model suggest that the use of {sup 36}Cl along with a purely spallogenic nuclide to determine erosion rates and exposure times should be less sensitive to analytical error than are determinations from two purely spallogenic nuclides. 31 refs., 7 figs., 3 tabs.

  9. Some possible evolutionary scenarios suggested by 36Cl measurements in Guarani aquifer groundwaters.

    PubMed

    Cresswell, R G; Bonotto, D M

    2008-08-01

    The Guarani aquifer underlies 1.2 M km2 in the Paraná sedimentary basin of South America and is an important source of water for industry, agriculture, and domestic supplies. To determine the sustainability of this aquifer we need to understand the dynamics of the groundwater system. This paper describes the first 36Cl measurements on aquifer groundwaters and some measurements on South American rainwaters, thought to be indicative of the recharge water. The results are compared to previous work in the region, including other radioisotope analyses. A simple model is developed, incorporating radioactive decay, allowing scenarios to be developed for mixing different waters at different mixing rates. Thus, mixing scenarios consistent with other hydrogeological and hydrogeochemical data could be assessed. A model that mixes fresh recharging waters with formational waters, that contain elevated chloride levels, but low (in situ) 36Cl levels, can explain most of the results presented here. The expectation that rainwater samples would provide a good end-member for modelling recharge proved problematic, however. As a consequence, it is suggested that either: the recharge waters are not sourced from the same locations as the rains; that the current rainfall and fallout conditions were significantly different in the past; or that the low levels of chloride in rainfall may have allowed some contamination of the samples by old (36Cl-free) chloride during the recharge process.

  10. Cosmogenic 36Cl ages of Quaternary basalt flows in the Mojave Desert, California, USA

    NASA Astrophysics Data System (ADS)

    Phillips, Fred M.

    2003-07-01

    Basalt flows provide excellent opportunities for calibration and intercomparison of Quaternary dating methods, remote sensing methods, and rates of geomorphic processes. The immediate motivation for this study was to provide chronology for a blind test of the utility of rock varnish microstratigraphy as an indicator of the age of flow emplacement. Five basaltic eruptive centers in the Mojave Desert of California were sampled for cosmogenic 36Cl analysis. Multiple samples were taken from most centers and, with one exception, produced good agreement. Assuming a surficial erosion rate of 1 mm/kyr -1, the flows yielded the following ages: Amboy Crater, 79±5 ka; Pisgah Crater, 22.5±1.3 ka; Cima field, I-Cone, 27±1.3 ka; Cima field, A-Cone, 21±1.6 ka and 11.5±1.5 ka; Cima field, flow of unidentified origin, 46±2 ka. The ages from the Cima I and A cones are in good agreement with previous cosmogenic 3He dating. Ages from the three previously undated flows are significantly older than previous estimates based on flow appearance. Tanzhou Liu performed varnish microstratigraphic analysis on samples collected from the same sites. His results were submitted for publication without knowledge of the 36Cl ages. His age estimates agree well with the 36Cl ages for the three previously undated flows, strongly supporting the validity of varnish microstratigraphy as a chronological correlation tool.

  11. Cosmogenic 36Cl in karst waters from Bunker Cave North Western Germany - A tool to derive local evapotranspiration?

    NASA Astrophysics Data System (ADS)

    Münsterer, C.; Fohlmeister, J.; Christl, M.; Schröder-Ritzrau, A.; Alfimov, V.; Ivy-Ochs, S.; Wackerbarth, A.; Mangini, A.

    2012-06-01

    Monthly rain and drip waters were collected over a period of 10 months at Bunker Cave, Germany. The concentration of 36Cl and the 36Cl/Cl-ratios were determined by accelerator mass spectrometry (AMS), while stable (35+37)Cl concentrations were measured with both, ion chromatography (IC) and AMS. The measured 36Cl-fluxes of (0.97 ± 0.57) × 104 atoms cm-2 month-1 (0.97 atoms m-2 month-1) in precipitation were on average twice as high as the global mean atmospheric production rate. This observation is consistent with the local fallout pattern, which is characterized by a maximum at mid-latitudes. The stable chloride concentration in drip waters (ranging from 13.2 to 20.9 mg/l) and the 36Cl-concentrations (ranging from 16.9 × 106 to 35.3 × 106 atoms/l) are a factor of 7 and 10 above the values expected from empirical evapotranspiration formulas and the rain water concentrations, respectively. Most likely the additional stable Cl is due to human impact from a nearby urban conglomeration. The large 36Cl-enrichment is attributed to the local evapotranspiration effect, which appears to be higher than the calculated values and to additional bomb-derived 36Cl from nuclear weapons tests in the 1950s and 60s stored in the soil above the cave. In the densely vegetated soil above Bunker Cave, 36Cl seems not to behave as a completely conservative tracer. The bomb derived 36Cl might be retained in the soil due to uptake by minerals and organic material and is still being released now. Based on our data, the residence time of 36Cl in the soil is estimated to be about 75-85 years.

  12. Determination of paleoseismic activity over a large time-scale: Fault scarp dating with 36Cl

    NASA Astrophysics Data System (ADS)

    Mozafari Amiri, Nasim; Tikhomirov, Dmitry; Sümer, Ökmen; Özkaymak, Çaǧlar; Uzel, Bora; Ivy-Ochs, Susan; Vockenhuber, Christof; Sözbilir, Hasan; Akçar, Naki

    2016-04-01

    Bedrock fault scarps are the most direct evidence of past earthquakes to reconstruct seismic activity in a large time-scale using cosmogenic 36Cl dating if built in carbonates. For this method, a surface along the fault scarp with a minimum amount of erosion is required to be chosen as an ideal target point. The section of the fault selected for sampling should cover at least two meters of the fault surface from the lower part of the scarp, where intersects with colluvium wedge. Ideally, sampling should be performed on a continuous strip along the direction of the fault slip direction. First, samples of 10 cm high and 15 cm wide are marked on the fault surface. Then, they are collected using cutters, hammer and chisel in a thickness of 3 cm. The main geometrical factors of scarp dip, scarp height, top surface dip and colluvium dip are also measured. Topographic shielding in the sampling spot is important to be estimated as well. Moreover, density of the fault scarp and colluvium are calculated. The physical and chemical preparations are carried in laboratory for AMS and chemical analysis of the samples. A Matlab® code is used for modelling of seismically active periods based on increasing production rate of 36Cl following each rupture, when a buried section of a fault is exposed. Therefore, by measuring the amount of cosmogenic 36Cl versus height, the timing of major ruptures and their offsets are determined. In our study, Manastır, Mugırtepe and Rahmiye faults in Gediz graben, Priene-Sazlı, Kalafat and Yavansu faults in Büyük Menderes graben and Ören fault in Gökava half-graben have been examined in the seismically active region of Western Turkey. Our results reconstruct at least five periods of high seismic activity during the Holocene time, three of which reveal seismic ruptures beyond the historical pre-existing data.

  13. FINDING TRACERS FOR SUPERNOVA PRODUCED {sup 26}Al

    SciTech Connect

    Young, Patrick A.; Ellinger, Carola I.; Arnett, David; Fryer, Chris L.; Rockefeller, Gabriel

    2009-07-10

    We consider the cospatial production of elements in supernova explosions to find observationally detectable proxies for enhancement of {sup 26}Al in supernova ejecta and stellar systems. Using four progenitors, we explore a range of one-dimensional explosions at different energies and an asymmetric three-dimensional explosion. We find that the most reliable indicator of the presence of {sup 26}Al in unmixed ejecta is a very low S/Si ratio ({approx}0.05). Production of N in O/S/Si-rich regions is also indicative. The biologically important element P is produced at its highest abundance in the same regions. Proxies should be detectable in supernova ejecta with high spatial resolution multiwavelength observations, but the small absolute abundance of material injected into a proto-planetary disk makes detection unlikely in existing or forming stellar/planetary systems.

  14. Depth dependence of soil carbonate accumulation based on cosmogenic [sup 36]Cl dating

    SciTech Connect

    Liu, B.; Phillips, F.M. ); Elmore, D.; Sharma, P. )

    1994-12-01

    Indurated pedogenic carbonate layers (calcretes) are common in soils on stable surfaces in arid to semiarid climates. The morphology and composition of calcretes provide important information on the geomorphic and climatic histories of the regions where they are formed, but they have proved difficult to date with conventional radiometric methods. We report cosmogenic [sup 36]Cl-buildup ages from three fractions (leachable Cl, carbonate, silicate) of a calcrete from the surface of an alluvial slope below the Ajo Mountains in southern Arizona. All three fractions give reasonably concordant ages, ranging from 700 ka at the base of the calcrete horizon to 200 ka at its top. These ages are in good agreement both with estimates of age based on correlation with similar, independently dated, soils in the region and with [sup 36]Cl-buildup ages on surficial boulders. These results support the ideas that calcretes accumulate upward with time and that water movement through the carbonate matrix is very limited after induration. 19 refs., 2 figs., 1 tab.

  15. 36Cl/Cl ratios in geothermal systems: preliminary measurements from the Coso Field

    SciTech Connect

    Nimz, G.J.; Moore, J.N.; Kasameyer, P.W.

    1997-07-01

    The {sub 36}Cl/Cl isotopic composition of chlorine in geothermal systems can be a useful diagnostic tool in characterizing hydrologic structure, in determining the origins and age of waters within the systems, and in differentiating the sources of chlorine (and other solutes) in the thermal waters. The {sub 36}Cl/Cl values for several geothermal water samples and reservoir host rock samples from the Coso, California geothermal field have been measured for these purposes. The results indicate that most of the chlorine is not derived from the dominant granitoid that host the geothermal system. If the chlorine was originally input into the Coso subsurface through meteoric recharge, that input occurred at least 1-1.25 million years ago. The results suggest that the thermal waters could be connate waters derived from sedimentary formations, presumably underlying and adjacent top the granitic rocks, which have recently migrated into the host rocks. Alternatively, most of the chlorine but not the water, may have recently input into the system from magmatic sources. In either case, the results indicate that most of the chlorine in the thermal waters has existed within the granitoid host rocks for no more than about 100,00-200,00 years. this residence time for the chlorine is similar to residence times suggested by other researchers for chlorine in deep groundwaters of the Mono Basin north of the Coso field.

  16. 36Cl measurements in Hiroshima granite samples as part of an international intercomparison study. Results from the Munich group.

    PubMed

    Huber, T; Rühm, W; Hoshi, M; Egbert, S D; Nolte, E

    2003-04-01

    Within the effort to resolve the so-called Hiroshima neutron discrepancy, an international intercomparison study has been carried out on granite samples from Hiroshima, with participating institutions from Japan, the US, and Germany. (36)Cl and (152)Eu produced in these samples by thermal neutrons from the A-bomb explosion were assessed independently by means of different techniques. At the Maier-Leibnitz-Laboratory near Munich, Germany, (36)Cl concentrations were measured by accelerator mass spectrometry. Measured (36)Cl/Cl ratios ranged from 1,670 x 10(-13) (at a distance of 146 m from the hypocenter) to 2.2 x 10(-13) (at a distance of 1,163 m from the hypocenter). One granite sample not exposed to A-bomb neutrons was measured as a control, and a (36)Cl/Cl ratio of 2.6 x 10(-13) was obtained. On average, our experimental results are 20-30% lower than those provided by model calculations based on the dosimetry system DS86. The results presented here do not support previous assessments of (36)Cl, (60)Co, and (152)Eu which had suggested much larger thermal neutron fluences than those calculated on the basis of DS86 for distances from the hypocenter of more than 1,000 m.

  17. Short lived 36Cl and its decay products 36Ar and 36S in the early solar system

    NASA Astrophysics Data System (ADS)

    Turner, G.; Crowther, S. A.; Burgess, R.; Gilmour, J. D.; Kelley, S. P.; Wasserburg, G. J.

    2013-12-01

    Variable excesses of 36S have previously been reported in sodalite in the Allende and Ningqiang meteorites and used to infer the presence of 36Cl in the early solar system. Until now no unambiguous evidence of the major decay product, 36Ar (98%), has been found. Using low fluence fast neutron activation we have measured small amounts of 36Ar in the Allende sodalite Pink Angel, corresponding to 36Cl/35Cl = (1.9 ± 0.5) × 10-8. This is a factor of 200 lower than the highest value inferred from 36S excesses in sodalite. High resolution I-Xe analyses confirm that the sodalite formed between 4561 and 4558 Ma ago. The core of Pink Angel sodalite yielded a precise formation age of 4559.4 ± 0.6 Ma. Deposition of sodalite containing live 36Cl, seven million years or so after the formation of the CAI, appears to require a local production mechanism involving intense neutron irradiation within the solar nebula. The constraint imposed by the near absence of neutron induced 128Xe is most easily satisfied if the 36Cl were produced in a fluid precursor of the sodalite. The low level of 36Ar could be accounted for as a result of residual in-situ36Cl decay, up to 1-2 Ma after formation of the sodalite, and/or later diffusive loss, in line with the low activation energy for Ar diffusion in sodalite.

  18. (26)Al investigations at the AMS-laboratory in Lund.

    PubMed

    Faarinen, M; Magnusson, C E; Hellborg, R; Mattsson, S; Kiisk, M; Persson, P; Schütz, A; Skog, G; Stenström, K

    2001-11-01

    At the accelerator mass spectrometry (AMS) laboratory in Lund, a facility for (26)Al analysis is under development. The sensitivity is expected to be several orders of magnitude higher than with standard mass spectrometry. The planned biomedical program includes studies of aluminium uptake, distribution and retention in man. The initial work has been concentrated on the construction and testing of a new dedicated injector for the accelerator and on the preparation of biological samples for aluminium analysis. The current quality of the facility is presented and the first experimental results reported. PMID:11709214

  19. Inventory of site-derived {sup 36}Cl in the Snake River plain aquifier, Idaho National Engineering Laboratory, Idaho

    SciTech Connect

    Beasley, T.M.

    1995-02-01

    Radioactive waste management practices at the U.S. Department of Energy`s Idaho National Engineering Laboratory (INEL) in Idaho have introduced {sup 36}Cl (T{sub 1/2} = 301,000 yr) into the Snake River Plain aquifer underlying the site. The {sup 36}Cl is believed to originate from neutron activation of stable {sup 35}Cl in nuclear fuels (principally) and in reactor cooling/process water. Wastewater releases of {sup 3}H at the INEL have been documented by the site operators for the period 1952 to 1988. During this time, approximately 1.2 PBq of {sup 3}H (30,000 Ci) were introduced to the subsurface through disposal wells and seepage ponds. By sampling a number of monitoring and production wells downgradient from points of introduction, {sup 3}H movement and dispersion in the groundwater have been documented by the U.S. Geological Survey. The present report uses these historical {sup 3}H release and monitoring data to choose hydrologic parameters (matrix porosity and plume penetration depth) that produce concordance between the {sup 3}H release estimates and the inventory calculated from measurements of {sup 3}H in the subsurface. These parameters are then applied to {sup 36}Cl isopleths to generate an estimated {sup 36}Cl inventory in the subsurface. Using assumptions about irradiation times, neutron fluxes, and total fuel processed, as little as 23 g of stable chloride impurity in fuel elements would be adequate to produce the amount of {sup 36}Cl estimated to be in the groundwaters underlying the site. The highest atom concentration of {sup 36}Cl measured onsite (222x10{sup 10} atoms 1{sup -1}) corresponds to an activity level of {approximately}4 pCi 1{sup -1} and represents 0.2 percent of the U.S. Environmental Protection Agency`s (EPA) drinking water standard for this radionuclide (2000 pCi 1{sup -1}).

  20. Age and geomorphic history of Meteor Crater, Arizona, from cosmogenic 36Cl and 14C in rock varnish

    USGS Publications Warehouse

    Phillips, F.M.; Zreda, M.G.; Smith, S.S.; Elmore, D.; Kubik, P.W.; Dorn, R.I.; Roddy, D.J.

    1991-01-01

    Using cosmogenic 36Cl buildup and rock varnish radiocarbon, we have measured the exposure age of rock surfaces at Meteor Crater, Arizona. Our 36Cl measurements on four dolomite boulders ejected from the crater by the impact yield a mean age of 49.7 ?? 0.85 ka, which is in excellent agreement with an average age of 49 ?? 3 ka obtained from thermoluminescence studies on shock-metamorphosed dolomite and quartz. These ages are supported by undetectably low 14C in the oldest rock varnish sample. ?? 1991.

  1. 10Be in bauxite and commercial aluminum

    NASA Astrophysics Data System (ADS)

    Middleton, R.; Klein, J.; Dezfouly-Arjomandy, B.; Albrecht, A.; Xue, S.; Herzog, G. F.; Gregory, J.

    1994-06-01

    Five different samples of commercial aluminum have 10Be concentrations that range from a low of 40 × 10 6 to a high of 100 × 10 6 (atom 10Be)/(g Al). The beryllium-10 is probably produced in the atmosphere and introduced into aluminum ore deposits in varying amounts by rainwater during ore genesis. One modern ore, a bauxite from Haiti, contains ~ 6 × 10 9 atom 10Be/(g sample) or 5.7 × 10 10 atom 10Be/(g Al). Geologically older, allocthonous bauxite from Arkansas contains considerably less 10Be; this observation suggests that 10Be can be used to constrain the age of the deposit. The presence of 10Be in commercial aluminum makes it inadvisable to add modern Al to small samples in which very low levels of 10Be are to be determined.

  2. Cosmic-ray production rates of He-, Ne- and Ar-isotopes in H-chondrites based on 36Cl-36Ar-ages

    NASA Astrophysics Data System (ADS)

    Leya, I.; Graf, Th.; Nishiizumi, K.; Wieler, R.

    2001-07-01

    We present the concentrations and isotopic compositions of He, Ne, and Ar for non-magnetic fractions and bulk samples of 17 H-chondrites which were recently investigated for their 36Cl-36Ar cosmic-ray exposure ages (Graf et al., 2001). All selected meteorites are observed falls with cosmic-ray exposure ages close to the 7 Ma peak. The rare gas data are consistent with 10Be and 36Cl production rates in the metal phase. Remarkably, only one out of the 17 H-chondrites, Bath, shows clear indications for a complex exposure history. Based on rare gas concentrations and 36Cl-36Ar exposure ages, 21Ne production rates as a function of 22Ne/21Ne and a mean 38Ar production rate are determined. The results confirm model calculations which predict that the relationship between 21Ne production rates and 22Ne/21Ne is ambiguous for high shielding. Besides the mean 38Ar production rate we also give production rate ratios P(38Ar from Ca) / P(38Ar from Fe). They vary between 10 and 77, showing no significant correlation with 38Ar-concentrations or 22Ne/21Ne. By investigating the metal-separates, Graf et al. (2001) found significant 3He deficits for six out of the 17 meteorites. For the non-magnetic fractions and bulk samples investigated here the data points in a 3He/21Ne versus 22Ne/21Ne diagram plot in the area defined by most of the H-chondrites. This means that 3He deficits in the metal phase are much more pronounced than in silicate minerals and we will argue that 3H diffusive losses in meteorites should be the rule rather than the exception. The 21Ne exposure ages, calculated on the basis of modeled 21Ne production rates, confirm the assumption by Graf et al. (2001) that the H5-chondrites with low 3He/38Ar in the metal formed in a separate event than those with normal 3He/38Ar ratios. The data can best be interpreted by assuming that the prominent 7 Ma exposure age peak of the H-chondrites is due to at least two events about 7.0 and 7.6 Ma ago.

  3. 10Be accumulation in a soil chronosequence

    USGS Publications Warehouse

    Pavich, M.J.; Brown, L.; Klein, J.; Middleton, R.

    1984-01-01

    We have measured the concentration of the cosmogenic isotope 10Be in soil samples from various horizons at six sites, including three independently dated Rappahannock River terraces and a previously undated Piedmont soil to which we have assigned an age. All of the incident 10Be can be accounted for in one of these soils and a second is within a factor of two. In three soils, whose concentrations vary widely with depth, a significant fraction of the incident 10Be cannot be accounted for. Incomplete sampling, and enhanced Be mobility caused by organic components, are the probable reasons for the low inventory of Be from these three soils. Overall, the data from these six sites indicate that 10Be accumulation could be used to assign ages to soils if Be is not mobilized and lost from the soil profile. ?? 1984.

  4. Cosmogenic 10Be and Noble Gases in Diogenites

    NASA Astrophysics Data System (ADS)

    Welten, K. C.; Lindner, L.; van der Borg, K.; Loeken, Th.; Scherer, P.; Schultz, L.

    1993-07-01

    Introduction: A recent reevaluation of the 3He, 21Ne, and 38Ar cosmic-ray exposure ages of eight non-Antarctic and three Antarctic diogenite falls led to a consistent set of exposure ages with a major cluster at 22 Ma and a possible second cluster around 40 Ma [1]. These clusters coincide with two major peaks in the exposure-age distributions of the genetically related eucrites and howardites [2], but the scarcity of young diogenites is remarkable [3]. An update of the exposure-age distribution for diogenites, including nine separate Antarctic falls, will be presented and possible differences in exposure history between Antarctic and non-Antarctic diogenites will be discussed. The exposure-age distributions of eucrites and howardites are still controversial [2,3], as conventional shielding corrections--on the basis of the 22Ne/21Ne ratio--cannot be applied. Therefore, the use of other shielding parameters, such as 10Be or 26Al, is considered. We examined the relation between 10Be contents and 22Ne/21Ne ratios in diogenites to obtain more insight into the shielding sensitivity of the 10Be production rate. Experimental: In addition to the existing database of more than 30 noble gas analyses [4] we carried out noble gas measurements on 5 non-Antarctic diogenites and on 12 Antarctic samples from 9 separate falls. On the same samples 10Be was measured by AMS. The experimental uncertainties in the 10Be values are 2-3%, those in the 22Ne/21Ne ratios are 0.5-1.0%. Results and Conclusions: The major exposure-age cluster at 22 Ma contains about 45% of the diogenite falls, indicating a major impact on its parent body. However, the presence of several younger diogenites suggests that this collisional event was not necessarily as destructive as previously suggested [3]. Four diogenites show exposure ages around 40 Ma, indicating a second major impact on the HED parent body. Although some Antarctic diogenites have unique mineralogical features [5,6], we didn't find any evidence

  5. Towards improvement of aluminium assay in quartz for in situ cosmogenic 26Al analysis at ANSTO

    NASA Astrophysics Data System (ADS)

    Fujioka, Toshiyuki; Fink, David; Mifsud, Charles

    2015-10-01

    Accuracy and precision in the measurement of natural aluminium abundances in quartz can affect the reliability of 26Al exposure dating and 26Al/10Be burial dating. At ANSTO, aliquots extracted from the HF solutions of dissolved quartz are treated in our laboratory, whereas ICP-OES analysis is performed at a commercial laboratory. The long-term inter-run reproducibility of our in-house standards show a limiting precision in Al measurements of 3-4% (1σ), which is lower than the claimed precision of Al analysis by ICP-OES. This indicates that unaccounted random errors are incorporated during our aliquot preparation. In this study, we performed several controlled tests to investigate effects of possible inconsistencies and variances during our aliquot preparation procedure. The results indicate that our procedure is robust against any subtle change in the preparation procedure, e.g., fuming temperatures, fuming reagents, and drying conditions. We found that the density of the solutions dispatched for ICP analysis is occasionally variable due to the presence of residual fuming reagents in the solution. A comparison of the results between the calibration curve and standard addition methods show that the former results are consistently lower than the latter by up to ∼14%. Similar offsets have been reported by previous studies. The reason for these discrepancies is mostly likely matrix effect, which is not accounted for by the calibration curve method. Further tests by varying matrix with impurities such as HF, HClO4, H2SO4 and Si identified that Si could cause lower offset in Al measurements; however, our ICP solutions are confirmed to be free from Si and the cause of matrix effect remains to be investigated. Hence, care must be taken for the measurement of Al concentrations in quartz by ICP-OES, either by ensuring that matrix effect is fully accounted for or by routinely employing standard additions when required.

  6. Using 36Cl data to quantify the paleorecharge in arid region. Example of the North Western Saharan Aquifer System.

    NASA Astrophysics Data System (ADS)

    Oriane Petersen, Jade; Deschamps, Pierre; Gonçalvès, Julio; Hamelin, Bruno; Michelot, Jean-Luc; Guendouz, Abdelhamid; Zouari, Kamel

    2014-05-01

    A comprehensive understanding of large-scale systems such as multi-layer aquifers in sedimentary basins (e.g. North Western Saharan Aquifer System -NWSAS- or the Great Artesian Basin) requires to investigate the recharge history to Quaternary timescale. In fact, for such systems, the residence time of groundwater is often in the order of 100 000 years to 1 million years, the recharge occurring during past, intermittent humid periods paced by the quaternary climatic cycles. In this study, we propose to reconstruct the history of the recharge over the Continental Intercalaire (CI) aquifer, one of the two main aquifers of the NWSAS. It extends over 1 million km2, shared between Algeria, Tunisia and Libya. We focus on the main recharge area of the CI aquifer located in the Algerian Atlas Mountains. Existing chlorine-36 data (36Cl half-life: 301 ka) indicate that groundwater residence time in this system is around 1 million years. A set of modeling approaches is combined to model the theoretical 36Cl/Cl distribution within the aquifer as a function of different recharge scenarios. Seventeen 36Cl/Cl data from two distinct flowpaths provide temporal constraints on groundwater ages. A simple piston model is used to simulate the distribution of theoretical 36Cl along these flowlines as a function of the distance from the outcrop with respect to a recharge scenario. Simplified climatic scenarios are constructed considering humid periods only during interglacial cycles. This allows to define 9 recharge rates (Rh(i)) associated to last interglacials (from marine isotope stages MIS1 to MIS19). In addition, a constant recharge Rg was considered during glacial periods. For each recharge scenario, the recharge values are constrained by using a Markov Chain Monte Carlo (MCMC) inversion, which yields the best agreement between measured and modeled 36Cl/Cl. This MCMC probabilistic inversion approach allows identifying plausible sets of the 10 parameters (9 Rh(i) and Rg) involved in

  7. Evidence from cosmic-ray exposure dating based on 36Cl for the pre-Minoan caldera on Santorini, Greece

    NASA Astrophysics Data System (ADS)

    Athanassas, Constantin; Bourlès, Didier; Braucher, Regis; Druitt, Tim; Nomikou, Paraskevi; Léanni, Laetitia

    2016-04-01

    The physiography of Santorini prior to the Minoan (Late Bronze Age) eruption (17th century BCE) is of great archaeological interest, given the importance of Santorini as a commercial centre and port in the Minoan empire. However, the paleogeography of the pre-Minoan caldera has been a point of controversy: Heiken and McCoy (1984) advocated the existence, in the southern part of the present-day caldera, of a pre-existing caldera formed during the 172 ka Lower Pumice eruption, whereas Druitt and Francaviglia (1992), based on the presence of in situ plinian pumice from the Minoan eruption adhering to the modern cliff, conceived the pre-Minoan (22 ka) caldera as having occupied much of the northern basin of the present-day caldera. With the goal of settling the debate we performed cosmic ray exposure dating employing in situ-produced cosmogenic 36Cl to date different generations of caldera cliffs at Santorini, and hence to identify those cliffs predating the Minoan eruption. Our methodology involved the determination of the in situ-produced cosmogenic 36Cl in basaltic and andesitic rocks cropping out in the cliffs. The samples returned 36Cl CRE ages consistent with previously published field mapping of cliff populations based on geomorphological and stratigraphic arguments (Druitt and Francaviglia 1992), suggesting that much of the present cliff line of northern Santorini predated the Minoan eruption, or was superficially modified by landslips and rockfalls during that eruption. The 36Cl CRE ages enable us to better define the paleogeography of the pre-Minoan caldera. References [1] Druitt, T. H. and Francaviglia, V.1992. Caldera formation on Santorini and the physiography of the islands in the Late Bronze Age. Bulletin of Volcanology 54, 484-493. [2] Heiken G and McCoy F (1984) Caldera development during the Minoan eruption, Thira, Cyclades, Greece. Journal of Geophysical Research: 89 (B10), 8841-8862.

  8. Total radioactive residues and residues of [36Cl]chlorate in market size broilers.

    PubMed

    Smith, David J; Byrd, James A; Anderson, Robin C

    2007-07-11

    The oral administration of chlorate salts reduces the numbers of Gram-negative pathogens in gastrointestinal tracts of live food animals. Although the efficacy of chlorate salts has been demonstrated repeatedly, the technology cannot be introduced into commercial settings without first demonstrating that chlorate residues, and metabolites of chlorate remaining in edible tissues, represent a negligible risk to consumers. Typically, a first step in this risk assessment is to quantify the parent compound and to identify metabolites remaining in edible tissues of animals treated with the experimental compound. The objectives of this study were to determine the pathway(s) of chlorate metabolism in market broilers and to determine the magnitude of chlorate residues remaining in edible tissues. To this end, 12 broilers (6 weeks; 2.70+/-0.34 kg) were randomly assigned to three treatments of 7.4, 15.0, and 22.5 mM sodium [36Cl]chlorate dissolved in drinking water (n=4 broilers per treatment). Exposure to chlorate, dissolved in drinking water, occurred at 0 and 24 h (250 mL per exposure), feed was withdrawn at hour 38, water was removed at hour 48, and birds were slaughtered at hour 54 (16 h after feed removal and 8 h after water removal). The radioactivity was rapidly eliminated in excreta with 69-78% of the total administered radioactivity being excreted by slaughter. Total radioactive residues were proportional to dose in all edible tissues with chloride ion comprising greater than 98.5% of the radioactive residue for the tissue (9.4-97.8 ppm chlorate equivalents). Chlorate residues were typically greatest in the skin (0.33-0.82 ppm), gizzard (0.1-0.137 ppm), and dark muscle (0.05-0.14 ppm). Adipose, liver, and white muscle tissue contained chlorate concentrations from 0.03 to 0.13 ppm. In contrast, chlorate concentrations in excreta eliminated during the 6 h period prior to slaughter ranged from 53 to 71 ppm. Collectively, these data indicate that broilers rapidly

  9. Total radioactive residues and residues of [36Cl]chlorate in market size broilers.

    PubMed

    Smith, David J; Byrd, James A; Anderson, Robin C

    2007-07-11

    The oral administration of chlorate salts reduces the numbers of Gram-negative pathogens in gastrointestinal tracts of live food animals. Although the efficacy of chlorate salts has been demonstrated repeatedly, the technology cannot be introduced into commercial settings without first demonstrating that chlorate residues, and metabolites of chlorate remaining in edible tissues, represent a negligible risk to consumers. Typically, a first step in this risk assessment is to quantify the parent compound and to identify metabolites remaining in edible tissues of animals treated with the experimental compound. The objectives of this study were to determine the pathway(s) of chlorate metabolism in market broilers and to determine the magnitude of chlorate residues remaining in edible tissues. To this end, 12 broilers (6 weeks; 2.70+/-0.34 kg) were randomly assigned to three treatments of 7.4, 15.0, and 22.5 mM sodium [36Cl]chlorate dissolved in drinking water (n=4 broilers per treatment). Exposure to chlorate, dissolved in drinking water, occurred at 0 and 24 h (250 mL per exposure), feed was withdrawn at hour 38, water was removed at hour 48, and birds were slaughtered at hour 54 (16 h after feed removal and 8 h after water removal). The radioactivity was rapidly eliminated in excreta with 69-78% of the total administered radioactivity being excreted by slaughter. Total radioactive residues were proportional to dose in all edible tissues with chloride ion comprising greater than 98.5% of the radioactive residue for the tissue (9.4-97.8 ppm chlorate equivalents). Chlorate residues were typically greatest in the skin (0.33-0.82 ppm), gizzard (0.1-0.137 ppm), and dark muscle (0.05-0.14 ppm). Adipose, liver, and white muscle tissue contained chlorate concentrations from 0.03 to 0.13 ppm. In contrast, chlorate concentrations in excreta eliminated during the 6 h period prior to slaughter ranged from 53 to 71 ppm. Collectively, these data indicate that broilers rapidly

  10. Heterogeneous Distribution of 26Al at the Birth of the Solar System

    NASA Astrophysics Data System (ADS)

    Makide, Kentaro; Nagashima, Kazuhide; Krot, Alexander N.; Huss, Gary R.; Ciesla, Fred J.; Hellebrand, Eric; Gaidos, Eric; Yang, Le

    2011-06-01

    It is believed that 26Al, a short-lived (t 1/2 = 0.73 Ma) and now extinct radionuclide, was uniformly distributed in the nascent solar system (SS) with the initial 26Al/27Al ratio of ~5.2 × 10-5, suggesting an external, stellar origin rather than local, solar source. However, the stellar source of 26Al and the manner in which it was injected into the SS remain controversial: the 26Al could have been produced by an asymptotic giant branch star, a supernova, or a Wolf-Rayet star and injected either into the protosolar molecular cloud, protosolar cloud core, or protoplanetary disk. Corundum (Al2O3) is predicted to be the first condensate from a cooling gas of solar composition. Here we show that micron-sized corundum condensates from 16O-rich (Δ17O ~ -25‰) gas of solar composition recorded heterogeneous distribution of 26Al at the birth of the SS: the inferred initial 26Al/27Al ratio ranges from ~6.5×10-5 to <2×10-6 52% of corundum grains measured are 26Al-poor. Abundant 26Al-poor, 16O-rich refractory objects include grossite- and hibonite-rich calcium-aluminum-rich inclusions (CAIs) in CH (high metal abundance and high iron concentration) chondrites, platy hibonite crystals in CM (Mighei-like) chondrites, and CAIs with fractionation and unidentified nuclear effects CAIs chondrites. Considering the apparently early and short duration (<0.3 Ma) of condensation of refractory 16O-rich solids in the SS, we infer that 26Al was injected into the collapsing protosolar molecular cloud and later homogenized in the protoplanetary disk. The apparent lack of correlation between 26Al abundance and O-isotope composition of corundum grains constrains the stellar source of 26Al in the SS.

  11. Production of 26Al by super-AGB stars

    NASA Astrophysics Data System (ADS)

    Siess, L.; Arnould, M.

    2008-10-01

    Context: Super AGB (SAGB) stars have initial masses ranging between 7-11 {M_⊙} and develop efficient hydrogen burning at the base of their convective envelope during their AGB evolution, leading to a substantial production of {}26Alg. Aims: We present the first discussion of the contribution of the SAGB stars to the galactic {}26Alg production, and we estimate the main uncertainties that affect the determination of the {}26Alg yields. Methods: The results of full stellar evolution computations are presented, with special emphasis on the {}26Alg yields from SAGB stars. We also use a postprocessing nucleosynthesis code to quantify the uncertainties associated with the nuclear reaction rates and with the treatment of convection that modifies the thermodynamical conditions at the base of the convective envelope. Results: Hot bottom burning leads to individual SAGB {}26Alg yields that are larger than those from intermediate mass stars, amounting to typical values as high as 5 × 10-5 {M_⊙}. The overall SAGB contribution remains modest, however, not exceeding 0.3 {M_⊙} of the estimated galactic content of 2.8 {M_⊙}. On the other hand, the SAGB 26Al/27Al ratios always exceed 0.01, which is commensurable with the values measured in some SiC grains considered to originate in C-rich AGB stars. However, the isotopic composition of some other elements, particularly nitrogen, is clearly at variance with the observations. We find that the {}26Alg yields are not affected by the pollution induced by the third dredge-ups, but that they strongly depend on the evolution of the temperature at the base of the convective envelope, the determination of which remains highly dependent on the specific convection model used in the stellar computations. Modifications of T_env by ± 10% leads to variations in the {}26Alg yields by a factor of 0.2 to 6. In comparison, the nuclear reaction rate uncertainties have less of an impact, altering the yields by less than a factor of 2.

  12. A 420 Year Annual 10Be Record from the WAIS Divide Ice Core

    NASA Astrophysics Data System (ADS)

    Woodruff, T. E.; Welten, K. C.; Caffee, M. W.; Nishiizumi, K.

    2011-12-01

    Annual ice layers archive the cosmogenic radionuclide 10Be, which is in turn an important proxy for solar activity, complementary to the 14C tree ring archive. Although production is primarily determined by the strength of the solar magnetic field 10Be deposition is also determined by local weather phenomena and snow accumulation rates, especially within shorter timescales. Accordingly, multiple ice core records of varying locations and accumulation rates are necessary to build a representative 10Be archive. We are presently engaged in a study to obtain continuous 10Be and 36Cl records in the West Antarctic Ice Sheet (WAIS) Divide ice core, a high snow accumulation site analogous to the GISP2 core from Greenland (Finkel and Nishiizumi1997). Here we present an annual resolution record of 10Be in the WAIS Divide core spanning the last 420 years including the Maunder (1645-1715 AD) and Dalton (1790-1830 AD) solar minima. Preliminary results for the periods of 1580-1740 and 1945-2006 AD show that the10Be flux during the Maunder Minimum was ~60% higher than in the last 60 years (4.8 vs. 3.0 x 105 atoms yr-1 cm-2). Although the low sunspot numbers during the Maunder Minimum suggest little change in solar activity, the 10Be data show that the heliomagnetic field strength continued to vary in a 11-year cycle, as observed in other annual 10Be records (e.g., Beer et al. 1990; Berggren et al. 2009). The 10Be record for the WAIS Divide core will be compared to 10Be records of Greenland ice cores as well as the 14C tree ring record. Acknowledgment. This work was supported by NSF grants ANT-0839042 and 0839137. Beer J. et al. 1990.Nature 347, 164. Finkel R. C. and Nishiizumi K. 1997.J. Geophys. Res. 102, 26,699. Berggren A.- M., et al. 2009. Geophys. Res. Lett. 36, L11801.

  13. "Groundwater ages" of the Lake Chad multi-layer aquifers system inferred from 14C and 36Cl data

    NASA Astrophysics Data System (ADS)

    Bouchez, Camille; Deschamps, Pierre; Goncalves, Julio; Hamelin, Bruno; Seidel, Jean-Luc; Doumnang, Jean-Claude

    2014-05-01

    Assessment of recharge, paleo-recharge and groundwater residence time of aquifer systems of the Sahel is pivotal for a sustainable management of this vulnerable resource. Due to its stratified aquifer system, the Lake Chad Basin (LCB) offers the opportunity to assess recharge processes over time and to link climate and hydrology in the Sahel. Located in north-central Africa at the fringe between the Sahel and the Sahara, the lake Chad basin (LCB) is an endorheic basin of 2,5.106 km2. With a monsoon climate, the majority of the rainfall occurs in the southern one third of the basin, the Chari/Logone River system transporting about 90% of the runoff generated within the drainage basin. A complex multi-layer aquifer system is located in the central part of the LCB. The Quaternary unconfined aquifer, covering 500 000 km2, is characterized by the occurrence of poorly understood piezometric depressions. Artesian groundwaters are found in the Plio-Pleistocene lacustrine and deltaic sedimentary aquifers (early Pliocene and Continental Terminal). The present-day lake is in hydraulic contact with the Quaternary Aquifer, but during past megalake phases, most of the Quaternary aquifer was submerged and may experience major recharge events. To identify active recharge area and assess groundwater dynamics, one hundred surface and groundwater samples of all layers have been collected over the southern part of the LCB. Major and trace elements have been analyzed. Measurements of 36Cl have been carried out at CEREGE, on the French 5 MV AMS National Facility ASTER and 14C activities have been analyzed for 17 samples on the French AMS ARTEMIS. Additionally, the stable isotopic composition was measured on the artesian aquifer samples. In the Quaternary aquifer, results show a large scatter with waters having very different isotopic and geochemical signature. In its southern part and in the vicinity of the surface waters, groundwaters are predominantly Ca-Mg-HCO3 type waters with very

  14. Evidence for Multiple Sources of 10 Be in the Early Solar System

    NASA Astrophysics Data System (ADS)

    Wielandt, Daniel; Nagashima, Kazuhide; Krot, Alexander N.; Huss, Gary R.; Ivanova, Marina A.; Bizzarro, Martin

    2012-04-01

    Beryllium-10 is a short-lived radionuclide (t 1/2 = 1.4 Myr) uniquely synthesized by spallation reactions and inferred to have been present when the solar system's oldest solids (calcium-aluminum-rich inclusions, CAIs) formed. Yet, the astrophysical site of 10Be nucleosynthesis is uncertain. We report Li-Be-B isotope measurements of CAIs from CV chondrites, including CAIs that formed with the canonical 26Al/27Al ratio of ~5 × 10-5 (canonical CAIs) and CAIs with Fractionation and Unidentified Nuclear isotope effects (FUN-CAIs) characterized by 26Al/27Al ratios much lower than the canonical value. Our measurements demonstrate the presence of four distinct fossil 10Be/9Be isochrons, lower in the FUN-CAIs than in the canonical CAIs, and variable within these classes. Given that FUN-CAI precursors escaped evaporation-recondensation prior to evaporative melting, we suggest that the 10Be/9Be ratio recorded by FUN-CAIs represents a baseline level present in presolar material inherited from the protosolar molecular cloud, generated via enhanced trapping of galactic cosmic rays. The higher and possibly variable apparent 10Be/9Be ratios of canonical CAIs reflect additional spallogenesis, either in the gaseous CAI-forming reservoir, or in the inclusions themselves: this indicates at least two nucleosynthetic sources of 10Be in the early solar system. The most promising locale for 10Be synthesis is close to the proto-Sun during its early mass-accreting stages, as these are thought to coincide with periods of intense particle irradiation occurring on timescales significantly shorter than the formation interval of canonical CAIs.

  15. EVIDENCE FOR MULTIPLE SOURCES OF {sup 10}Be IN THE EARLY SOLAR SYSTEM

    SciTech Connect

    Wielandt, Daniel; Krot, Alexander N.; Bizzarro, Martin; Nagashima, Kazuhide; Huss, Gary R.; Ivanova, Marina A.

    2012-04-01

    Beryllium-10 is a short-lived radionuclide (t{sub 1/2} = 1.4 Myr) uniquely synthesized by spallation reactions and inferred to have been present when the solar system's oldest solids (calcium-aluminum-rich inclusions, CAIs) formed. Yet, the astrophysical site of {sup 10}Be nucleosynthesis is uncertain. We report Li-Be-B isotope measurements of CAIs from CV chondrites, including CAIs that formed with the canonical {sup 26}Al/{sup 27}Al ratio of {approx}5 Multiplication-Sign 10{sup -5} (canonical CAIs) and CAIs with Fractionation and Unidentified Nuclear isotope effects (FUN-CAIs) characterized by {sup 26}Al/{sup 27}Al ratios much lower than the canonical value. Our measurements demonstrate the presence of four distinct fossil {sup 10}Be/{sup 9}Be isochrons, lower in the FUN-CAIs than in the canonical CAIs, and variable within these classes. Given that FUN-CAI precursors escaped evaporation-recondensation prior to evaporative melting, we suggest that the {sup 10}Be/{sup 9}Be ratio recorded by FUN-CAIs represents a baseline level present in presolar material inherited from the protosolar molecular cloud, generated via enhanced trapping of galactic cosmic rays. The higher and possibly variable apparent {sup 10}Be/{sup 9}Be ratios of canonical CAIs reflect additional spallogenesis, either in the gaseous CAI-forming reservoir, or in the inclusions themselves: this indicates at least two nucleosynthetic sources of {sup 10}Be in the early solar system. The most promising locale for {sup 10}Be synthesis is close to the proto-Sun during its early mass-accreting stages, as these are thought to coincide with periods of intense particle irradiation occurring on timescales significantly shorter than the formation interval of canonical CAIs.

  16. 26Al-containing acidic and basic sodium aluminum phosphate preparation and use in studies of oral aluminum bioavailability from foods utilizing 26Al as an aluminum tracer

    NASA Astrophysics Data System (ADS)

    Yokel, Robert A.; Urbas, Aaron A.; Lodder, Robert A.; Selegue, John P.; Florence, Rebecca L.

    2005-04-01

    We synthesized 26Al-containing acidic and basic (alkaline) sodium aluminum phosphates (SALPs) which are FDA-approved leavening and emulsifying agents, respectively, and used them to determine the oral bioavailability of aluminum incorporated in selected foods. We selected applicable methods from published syntheses (patents) and scaled them down (∼3000- and 850-fold) to prepare ∼300-400 mg of each SALP. The 26Al was incorporated at the beginning of the syntheses to maximize 26Al and 27Al equilibration and incorporate the 26Al in the naturally-occurring Al-containing chemical species of the products. Near infrared spectroscopy (NIR) and X-ray powder diffraction (XRD) were used to characterize the two SALP samples and some intermediate samples. Multi-elemental analysis (MEA) was used to determine Na, Al and P content. Commercial products were included for comparison. Satisfactory XRD analyses, near infrared spectra and MEA results confirmed that we synthesized acidic and basic SALP, as well as some of the syntheses intermediates. The 26Al-containing acidic and basic SALPs were incorporated into a biscuit material and a processed cheese, respectively. These were used in oral bioavailability studies conducted in rats in which the 26Al present in blood after its oral absorption was quantified by accelerator mass spectrometry. The results showed oral Al bioavailability from acidic SALP in biscuit was ∼0.02% and from basic SALP in cheese ∼0.05%, lower than our previous determination of Al bioavailability from drinking water, ∼0.3%. Both food and water can appreciably contribute to the Al absorbed from typical human Al intake.

  17. Timing of maximum glacial extent and deglaciation from HualcaHualca volcano (southern Peru), obtained with cosmogenic 36Cl.

    NASA Astrophysics Data System (ADS)

    Alcalá, Jesus; Palacios, David; Vazquez, Lorenzo; Juan Zamorano, Jose

    2015-04-01

    Andean glacial deposits are key records of climate fluctuations in the southern hemisphere. During the last decades, in situ cosmogenic nuclides have provided fresh and significant dates to determine past glacier behavior in this region. But still there are many important discrepancies such as the impact of Last Glacial Maximum or the influence of Late Glacial climatic events on glacial mass balances. Furthermore, glacial chronologies from many sites are still missing, such as HualcaHualca (15° 43' S; 71° 52' W; 6,025 masl), a high volcano of the Peruvian Andes located 70 km northwest of Arequipa. The goal of this study is to establish the age of the Maximum Glacier Extent (MGE) and deglaciation at HualcaHualca volcano. To achieve this objetive, we focused in four valleys (Huayuray, Pujro Huayjo, Mollebaya and Mucurca) characterized by a well-preserved sequence of moraines and roches moutonnées. The method is based on geomorphological analysis supported by cosmogenic 36Cl surface exposure dating. 36Cl ages have been estimated with the CHLOE calculator and were compared with other central Andean glacial chronologies as well as paleoclimatological proxies. In Huayuray valley, exposure ages indicates that MGE occurred ~ 18 - 16 ka. Later, the ice mass gradually retreated but this process was interrupted by at least two readvances; the last one has been dated at ~ 12 ka. In the other hand, 36Cl result reflects a MGE age of ~ 13 ka in Mollebaya valley. Also, two samples obtained in Pujro-Huayjo and Mucurca valleys associated with MGE have an exposure age of 10-9 ka, but likely are moraine boulders affected by exhumation or erosion processes. Deglaciation in HualcaHualca volcano began abruptly ~ 11.5 ka ago according to a 36Cl age from a polished and striated bedrock in Pujro Huayjo valley, presumably as a result of reduced precipitation as well as a global increase of temperatures. The glacier evolution at HualcaHualca volcano presents a high correlation with

  18. Seismic slip history of the Pizzalto fault (Central Apennines, Italy) using in situ 36Cl cosmogenic dating

    NASA Astrophysics Data System (ADS)

    Delli Rocioli, Mattia; Pace, Bruno; Benedetti, Lucilla; Visini, Francesco; Guillou, Valery; Bourlès, Didier; Arnorld, Maurice; Aumaître, Georges; Keddadouche, Karim

    2013-04-01

    A prerequisite to constrain fault-based and time-dependent earthquake rupture forecast models is to acquire data on the past large earthquake frequency on an individual seismogenic source. Here we present a paleoseismological study on the Pizzalto fault using the in situ produced cosmogenic nuclide 36Cl (Schlagenhauf et al., 2011). The Pizzalto fault, located in central Italy about 50 km southeast of the epicenter of L'Aquila 2009 earthquake, is about 12 km long, SW dipping and belongs to the 30 km long Rotella-Aremogna active normal fault system. Recent activity along the Pizzalto fault is suggested by the presence of a continuous and linear 2 to 5 m high limestone fault scarp that was sampled every 10 cm at a site located in its particularly well-preserved central portion. 49 samples have been chemically processed and measured, and their 36Cl and Cl concentrations have been determined using isotope dilution mass spectrometry at the French AMS national facility ASTER located at CEREGE. Modeling the in situ 36Cl concentration with the scarp height allow deciphering the age and slip of the last major earthquake events on the fault. To derive those earthquake parameters, we used the published Matlab code from Schlagenhauf et al. (2011) that we implemented with a Monte Carlo approach to explore a large number of earthquake recurrence scenarios varying both the number of events, their slip and their ages. The "a priori" constraints input in the Monte Carlo code were: 1-the number of events, which is given by the stacking of individual probability density functions (assumed to be Gaussian) of each sample concentration; and, 2-the cumulative slip that should be equal to the height of the fault scarp. The first results show that 36Cl concentrations are reproduced better considering five events occurring over the last 5 ka and a previous one at about 13 ka. This suggests that most earthquake events clustered during a period of intense seismic activity preceded by a longer

  19. Translocation of 125I, 75Se and 36Cl to wheat edible parts following wet foliar contamination under field conditions.

    PubMed

    Hurtevent, P; Thiry, Y; Levchuk, S; Yoschenko, V; Henner, P; Madoz-Escande, C; Leclerc, E; Colle, C; Kashparov, V

    2013-07-01

    Apart from radiocaesium and radiostrontium, there have been few studies on the foliar transfer of radionuclides in plants. Consequently, specific translocation factor (ftr) values for (129)I, (79)Se and (36)Cl are still missing from the IAEA reference databases. The translocation of short - lived isotopes, (125)I and (75)Se, and of (36)Cl to wheat grain were measured under field conditions following acute and chronic wet foliar contamination at various plant growth stages in the absence of leaching caused by rain. The translocation factors ranged from 0.02% to 1.1% for (125)I (a value similar to Sr), from 0.1% to 16.5% for (75)Se, and from 1% to 14.9% for (36)Cl. Both (36)Cl and (75)Se were as mobile as Cs. The phenomenological analysis showed that each element displayed a specific behavior. Iodide showed the lowest apparent mobility because of its preferential fixation in or on the leaves and a significant amount probably volatilized. Selenite internal transfer was significant and possibly utilized the sulphur metabolic pathway. However bio - methylation of selenite may have led to increased volatilization. Chloride was very mobile and quickly diffused throughout the plant. In addition, the analysis underlined the importance of plant growth responses to annual variations in weather conditions that can affect open field experiments because plant growth stage played a major role in ftr values dispersion. The chronic contamination results suggested that a series of acute contamination events had an additive effect on translocated elements. The highest translocation value obtained for an acute contamination event was shown to be a good conservative assessment of chronic contamination if data on chronic contamination translocation are lacking. The absence of rain leaching during the experiment meant that this investigation avoided potential radionuclide transfer by the roots, which also meant that radionuclide retention on or in the leaves was maximized. This study was

  20. The 10Be contents of SNC meteorites

    NASA Technical Reports Server (NTRS)

    Pal, D. K.; Tuniz, C.; Moniot, R. K.; Savin, W.; Vajda, S.; Kruse, T.; Herzog, G. F.

    1986-01-01

    Several authors have explored the possibility that the Shergottites, Nakhlites, and Chassigny (SNC) came from Mars. The spallogenic gas contents of the SNC meteorites have been used to: constrain the sizes of the SNC's during the last few million years; to establish groupings independent of the geochemical ones; and to estimate the likelihood of certain entries in the catalog of all conceivable passages from Mars to Earth. The particular shielding dependence of Be-10 makes the isotope a good probe of the irradiation conditions experienced by the SNC meteorites. The Be-10 contents of nine members of the group were measured using the technique of accelerator mass spectrometry. The Be-10 contents of Nakhla, Governador Valadares, Chassigny, and probably Lafayette, about 20 dpm/kg, exceed the values expected from irradiation of the surface of a large body. The Be-10 data therfore do not support scenario III of Bogard et al., one in which most of the Be-10 in the SNC meteorites would have formed on the Martian surface; they resemble rather the Be-10 contents found in many ordinary chondrites subjected to 4 Pi exposures. The uncertainties of the Be-10 contents lead to appreciable errors in the Be-10 ages, t(1) = -1/lambda ln(1 Be-10/Be-10). Nonetheless, the Be-10 ages are consistent with the Ne-21 ages calculated assuming conventional, small-body production rates and short terrestrial ages for the finds. It is believed that this concordance strengthens the case for at least 3 different irradiation ages for the SNC meteorites. Given the similar half-thicknesses of the Be-10 and Ne-21 production rates, the ratios of the Be-10 and Ne-21 contents do not appear consistent with common ages for any of the groups. In view of the general agreement between the Be-10 and Ne-21 ages it does not seem useful at this time to construct multiple-stage irradiation histories for the SNC meteorites.

  1. Tritium and 36Cl as constraints on fast fracture flow and percolation flux in the unsaturated zone at Yucca Mountain

    NASA Astrophysics Data System (ADS)

    Guerin, Marianne

    2001-10-01

    An analysis of tritium and 36Cl data collected at Yucca Mountain, Nevada suggests that fracture flow may occur at high velocities through the thick unsaturated zone. The mechanisms and extent of this "fast flow" in fractures at Yucca Mountain are investigated with data analysis, mixing models and several one-dimensional modeling scenarios. The model results and data analysis provide evidence substantiating the weeps model [Gauthier, J.H., Wilson, M.L., Lauffer, F.C., 1992. Proceedings of the Third Annual International High-level Radioactive Waste Management Conference, vol. 1, Las Vegas, NV. American Nuclear Society, La Grange Park, IL, pp. 891-989] and suggest that fast flow in fractures with minimal fracture-matrix interaction may comprise a substantial proportion of the total infiltration through Yucca Mountain. Mixing calculations suggest that bomb-pulse tritium measurements, in general, represent the tail end of travel times for thermonuclear-test-era (bomb-pulse) infiltration. The data analysis shows that bomb-pulse tritium and 36Cl measurements are correlated with discrete features such as horizontal fractures and areas where lateral flow may occur. The results presented here imply that fast flow in fractures may be ubiquitous at Yucca Mountain, occurring when transient infiltration (storms) generates flow in the connected fracture network.

  2. Tritium and 36Cl as constraints on fast fracture flow and percolation flux in the unsaturated zone at Yucca Mountain.

    PubMed

    Guerin, M

    2001-10-01

    An analysis of tritium and 36Cl data collected at Yucca Mountain, Nevada suggests that fracture flow may occur at high velocities through the thick unsaturated zone. The mechanisms and extent of this "fast flow" in fractures at Yucca Mountain are investigated with data analysis, mixing models and several one-dimensional modeling scenarios. The model results and data analysis provide evidence substantiating the weeps model [Gauthier, J.H., Wilson, M.L., Lauffer, F.C., 1992. Proceedings of the Third Annual International High-level Radioactive Waste Management Conference, vol. 1, Las Vegas, NV. American Nuclear Society, La Grange Park, IL, pp. 891-989] and suggest that fast flow in fractures with minimal fracture-matrix interaction may comprise a substantial proportion of the total infiltration through Yucca Mountain. Mixing calculations suggest that bomb-pulse tritium measurements, in general, represent the tail end of travel times for thermonuclear-test-era (bomb-pulse) infiltration. The data analysis shows that bomb-pulse tritium and 36Cl measurements are correlated with discrete features such as horizontal fractures and areas where lateral flow may occur. The results presented here imply that fast flow in fractures may be ubiquitous at Yucca Mountain, occurring when transient infiltration (storms) generates flow in the connected fracture network. PMID:11588829

  3. Tritium and 36Cl as constraints on fast fracture flow and percolation flux in the unsaturated zone at Yucca Mountain.

    PubMed

    Guerin, M

    2001-10-01

    An analysis of tritium and 36Cl data collected at Yucca Mountain, Nevada suggests that fracture flow may occur at high velocities through the thick unsaturated zone. The mechanisms and extent of this "fast flow" in fractures at Yucca Mountain are investigated with data analysis, mixing models and several one-dimensional modeling scenarios. The model results and data analysis provide evidence substantiating the weeps model [Gauthier, J.H., Wilson, M.L., Lauffer, F.C., 1992. Proceedings of the Third Annual International High-level Radioactive Waste Management Conference, vol. 1, Las Vegas, NV. American Nuclear Society, La Grange Park, IL, pp. 891-989] and suggest that fast flow in fractures with minimal fracture-matrix interaction may comprise a substantial proportion of the total infiltration through Yucca Mountain. Mixing calculations suggest that bomb-pulse tritium measurements, in general, represent the tail end of travel times for thermonuclear-test-era (bomb-pulse) infiltration. The data analysis shows that bomb-pulse tritium and 36Cl measurements are correlated with discrete features such as horizontal fractures and areas where lateral flow may occur. The results presented here imply that fast flow in fractures may be ubiquitous at Yucca Mountain, occurring when transient infiltration (storms) generates flow in the connected fracture network.

  4. HETEROGENEOUS DISTRIBUTION OF {sup 26}Al AT THE BIRTH OF THE SOLAR SYSTEM

    SciTech Connect

    Makide, Kentaro; Nagashima, Kazuhide; Krot, Alexander N.; Huss, Gary R.; Ciesla, Fred J.; Yang, Le; Hellebrand, Eric; Gaidos, Eric

    2011-06-01

    It is believed that {sup 26}Al, a short-lived (t{sub 1/2} = 0.73 Ma) and now extinct radionuclide, was uniformly distributed in the nascent solar system (SS) with the initial {sup 26}Al/{sup 27}Al ratio of {approx}5.2 x 10{sup -5}, suggesting an external, stellar origin rather than local, solar source. However, the stellar source of {sup 26}Al and the manner in which it was injected into the SS remain controversial: the {sup 26}Al could have been produced by an asymptotic giant branch star, a supernova, or a Wolf-Rayet star and injected either into the protosolar molecular cloud, protosolar cloud core, or protoplanetary disk. Corundum (Al{sub 2}O{sub 3}) is predicted to be the first condensate from a cooling gas of solar composition. Here we show that micron-sized corundum condensates from {sup 16}O-rich ({Delta}{sup 17}O {approx} -25 per mille ) gas of solar composition recorded heterogeneous distribution of {sup 26}Al at the birth of the SS: the inferred initial {sup 26}Al/{sup 27}Al ratio ranges from {approx}6.5x10{sup -5} to <2x10{sup -6}; 52% of corundum grains measured are {sup 26}Al-poor. Abundant {sup 26}Al-poor, {sup 16}O-rich refractory objects include grossite- and hibonite-rich calcium-aluminum-rich inclusions (CAIs) in CH (high metal abundance and high iron concentration) chondrites, platy hibonite crystals in CM (Mighei-like) chondrites, and CAIs with fractionation and unidentified nuclear effects CAIs chondrites. Considering the apparently early and short duration (<0.3 Ma) of condensation of refractory {sup 16}O-rich solids in the SS, we infer that {sup 26}Al was injected into the collapsing protosolar molecular cloud and later homogenized in the protoplanetary disk. The apparent lack of correlation between {sup 26}Al abundance and O-isotope composition of corundum grains constrains the stellar source of {sup 26}Al in the SS.

  5. {sup 26}Al IN THE EARLY SOLAR SYSTEM: NOT SO UNUSUAL AFTER ALL

    SciTech Connect

    Jura, M.; Xu, S.; Young, E. D. E-mail: sxu@astro.ucla.edu

    2013-10-01

    Recently acquired evidence shows that extrasolar asteroids exhibit over a factor of 100 variation in the iron to aluminum abundance ratio. This large range likely is a consequence of igneous differentiation that resulted from heating produced by radioactive decay of {sup 26}Al with an abundance comparable to that in the solar system's protoplanetary disk at birth. If so, the conventional view that our solar system began with an unusually high amount of {sup 26}Al should be discarded.

  6. 26Al- 26Mg and 207Pb- 206Pb systematics of Allende CAIs: Canonical solar initial 26Al/ 27Al ratio reinstated

    NASA Astrophysics Data System (ADS)

    Jacobsen, Benjamin; Yin, Qing-zhu; Moynier, Frederic; Amelin, Yuri; Krot, Alexander N.; Nagashima, Kazuhide; Hutcheon, Ian D.; Palme, Herbert

    2008-07-01

    The precise knowledge of the initial 26Al/ 27Al ratio [( 26Al/ 27Al) 0] is crucial if we are to use the very first solid objects formed in our Solar System, calcium-aluminum-rich inclusions (CAIs) as the "time zero" age-anchor and guide future work with other short-lived radio-chronometers in the early Solar System, as well as determining the inventory of heat budgets from radioactivities for early planetary differentiation. New high-precision multi-collector inductively-coupled plasma mass spectrometry (MC-ICP-MS) measurements of 27Al/ 24Mg ratios and Mg-isotopic compositions of nine whole-rock CAIs (six mineralogically characterized fragments and three micro-drilled inclusions) from the CV carbonaceous chondrite, Allende yield a well-defined 26Al- 26Mg fossil isochron with an ( 26Al/ 27Al) 0 of (5.23 ± 0.13) × 10 - 5 . Internal mineral isochrons obtained for three of these CAIs ( A44A, AJEF, and A43) are consistent with the whole-rock CAI isochron. The mineral isochron of AJEF with ( 26Al/ 27Al) 0 = (4.96 ± 0.25) × 10 - 5 , anchored to our precisely determined absolute 207Pb- 206Pb age of 4567.60 ± 0.36 Ma for the same mineral separates, reinstate the "canonical" ( 26Al/ 27Al) 0 of 5 × 10 - 5 for the early Solar System. The uncertainty in ( 26Al/ 27Al) 0 corresponds to a maximum time span of ± 20 Ka (thousand years), suggesting that the Allende CAI formation events were culminated within this time span. Although all Allende CAIs studied experienced multistage formation history, including melting and evaporation in the solar nebula and post-crystallization alteration likely on the asteroidal parent body, the 26Al- 26Mg and U-Pb-isotopic systematics of the mineral separates and bulk CAIs behaved largely as closed-system since their formation. Our data do not support the "supra-canonical" 26Al/ 27Al ratio of individual minerals or their mixtures in CV CAIs, suggesting that the supra-canonical 26Al/ 27Al ratio in the CV CAIs may have resulted from post

  7. Millennial strain partitioning and fault interaction revealed by 36Cl cosmogenic nuclide datasets from Abruzzo, Central Italy

    NASA Astrophysics Data System (ADS)

    Gregory, L. C.; Phillips, R. J.; Roberts, G.; Cowie, P. A.; Shanks, R. P.; McCaffrey, K. J. W.; Wedmore, L. N. J.; Zijerveld, L.

    2015-12-01

    In zones of distributed continental faulting, it is critical to understand how slip is partitioned onto brittle structures over both long-term millennial time scales and shorter-term individual earthquake cycles. The comparison of slip distributions on different timescales is challenging due to earthquake repeat-times being longer or similar to historical earthquake records, and a paucity of data on fault activity covering millennial to Quaternary scales in detail. Cosmogenic isotope analyses from bedrock fault scarps have the potential to bridge the gap, as these datasets track the exposure of fault planes due to earthquakes with better-than-millennial resolution. In this presentation, we will use an extensive 36Cl dataset to characterise late Holocene activity across a complicated network of normal faults in Abruzzo, Italy, comparing the most recent fault behaviour with the historical earthquake record in the region. Extensional faulting in Abruzzo has produced scarps of exposed bedrock limestone fault planes that have been preserved since the last glacial maximum (LGM). 36Cl accumulates in bedrock fault scarps as the plane is progressively exhumed by earthquakes and thus the concentration of 36Cl measured up the fault plane reflects the rate and patterns of slip. In this presentation, we will focus on the most recent record, revealed at the base of the fault. Utilising new Bayesian modelling techniques on new and previously collected data, we compare evidence for this most recent period of slip (over the last several thousands of years) across 5-6 fault zones located across strike from each other. Each sampling site is carefully characterised using LiDAR and GPR. We demonstrate that the rate of slip on individual fault strands varies significantly, between having periods of accelerated slip to relative quiescence. Where data is compared between across-strike fault zones and with the historical catalogue, it appears that slip is partitioned such that one fault

  8. Heating and melting of small icy satellites by the decay of 26Al

    NASA Technical Reports Server (NTRS)

    Prialnik, D.; Bar-Nun, A.; Owen, T. (Principal Investigator)

    1990-01-01

    We study the effect of radiogenic heating due to 26Al on the thermal evolution of small icy satellites. Our object is to find the extent of internal melting as a function of the satellite radius and of the initial 26Al abundance. The implicit assumption, based on observations of young stars, is that planet and satellite accretion occurred on a time scale of approximately 10(6) yr (comparable with the lifetime of 26Al). The icy satellites are modeled as spheres of initially amorphous ice, with chondritic abundances of 40K, 232Th, 235U, 238U, corresponding to an ice/dust mass ratio of 1. Evolutionary calculations are carried out, spanning 4.5 x 10(9) yr, for different combinations of the two free parameters. Heat transfer by subsolidus convection is neglected for these small satellites. Our main conclusion is that the initial 26Al abundance capable of melting icy bodies of satellite size to a significant extent is more than 10 times lower than that prevailing in the interstellar medium (or that inferred from the Ca-Al rich inclusions of the Allende meteorite, approximately 7 x 10(-7) by mass). We find, for example, that an initial 26Al mass fraction of approximately 4 x 10(-8) is sufficient for melting almost completely icy spheres with radii of 800 km, typical of the larger icy planetary satellites. We also find that for any given 26Al abundance, there is a narrow range of radii below which only marginal melting occurs and above which most of the ice melts (and refreezes later). Since extensive melting may have important consequences, such as differentiation, gas release, and volcanic activity, the effect of 26Al should be included in future studies of satellite interiors.

  9. Early accretion of protoplanets inferred from a reduced inner solar system 26Al inventory

    NASA Astrophysics Data System (ADS)

    Schiller, Martin; Connelly, James N.; Glad, Aslaug C.; Mikouchi, Takashi; Bizzarro, Martin

    2015-06-01

    The mechanisms and timescales of accretion of 10-1000 km sized planetesimals, the building blocks of planets, are not yet well understood. With planetesimal melting predominantly driven by the decay of the short-lived radionuclide 26Al (26Al→26Mg; t1/2 = 0.73 Ma), its initial abundance determines the permissible timeframe of planetesimal-scale melting and its subsequent cooling history. Currently, precise knowledge about the initial 26Al abundance [(26Al/27Al)0] exists only for the oldest known solids, calcium aluminum-rich inclusions (CAIs) - the so-called canonical value. We have determined the 26Al/27Al of three angrite meteorites, D'Orbigny, Sahara 99555 and NWA 1670, at their time of crystallization, which corresponds to (3.98 ± 0.15) ×10-7, (3.64 ± 0.18) ×10-7, and (5.92 ± 0.59) ×10-7, respectively. Combined with a newly determined absolute U-corrected Pb-Pb age for NWA 1670 of 4564.39 ± 0.24 Ma and published U-corrected Pb-Pb ages for the other two angrites, this allows us to calculate an initial (26Al/27Al)0 of (1.33-0.18+0.21) ×10-5 for the angrite parent body (APB) precursor material at the time of CAI formation, a value four times lower than the accepted canonical value of 5.25 ×10-5. Based on their similar 54Cr/52Cr ratios, most inner solar system materials likely accreted from material containing a similar 26Al/27Al ratio as the APB precursor at the time of CAI formation. To satisfy the abundant evidence for widespread planetesimal differentiation, the subcanonical 26Al budget requires that differentiated planetesimals, and hence protoplanets, accreted rapidly within 0.25 ± 0.15 Ma of the formation of canonical CAIs.

  10. Heating and melting of small icy satellites by the decay of 26Al.

    PubMed

    Prialnik, D; Bar-Nun, A

    1990-05-20

    We study the effect of radiogenic heating due to 26Al on the thermal evolution of small icy satellites. Our object is to find the extent of internal melting as a function of the satellite radius and of the initial 26Al abundance. The implicit assumption, based on observations of young stars, is that planet and satellite accretion occurred on a time scale of approximately 10(6) yr (comparable with the lifetime of 26Al). The icy satellites are modeled as spheres of initially amorphous ice, with chondritic abundances of 40K, 232Th, 235U, 238U, corresponding to an ice/dust mass ratio of 1. Evolutionary calculations are carried out, spanning 4.5 x 10(9) yr, for different combinations of the two free parameters. Heat transfer by subsolidus convection is neglected for these small satellites. Our main conclusion is that the initial 26Al abundance capable of melting icy bodies of satellite size to a significant extent is more than 10 times lower than that prevailing in the interstellar medium (or that inferred from the Ca-Al rich inclusions of the Allende meteorite, approximately 7 x 10(-7) by mass). We find, for example, that an initial 26Al mass fraction of approximately 4 x 10(-8) is sufficient for melting almost completely icy spheres with radii of 800 km, typical of the larger icy planetary satellites. We also find that for any given 26Al abundance, there is a narrow range of radii below which only marginal melting occurs and above which most of the ice melts (and refreezes later). Since extensive melting may have important consequences, such as differentiation, gas release, and volcanic activity, the effect of 26Al should be included in future studies of satellite interiors.

  11. A comparison of groundwater dating with 81Kr, 36Cl and 4He in four wells of the Great Artesian Basin, Australia

    NASA Astrophysics Data System (ADS)

    Lehmann, B. E.; Love, A.; Purtschert, R.; Collon, P.; Loosli, H. H.; Kutschera, W.; Beyerle, U.; Aeschbach-Hertig, W.; Kipfer, R.; Frape, S. K.; Herczeg, A.; Moran, J.; Tolstikhin, I. N.; Gröning, M.

    2003-06-01

    The isotopic ratios 81Kr/Kr and 36Cl/Cl and the 4He concentrations measured in groundwater from four artesian wells in the western part of the Great Artesian Basin (GAB) in Australia are discussed. Based on radioactive decay along a water flow path the 81Kr/Kr ratios are directly converted to groundwater residence times. Results are in a range of 225-400 kyr with error bars in the order of 15% primarily due to counting statistics in the cyclotron accelerator mass spectrometer measurement. Additional uncertainties from subsurface production and/or exchange with stagnant porewaters in the confining shales appear to be of the same order of magnitude. These 81Kr ages are then used to calibrate the 36Cl and the 4He dating methods. Based on elemental analyses of rock samples from the sandstone aquifer as well as from the confining Bulldog shale the in situ flux of thermal neutrons and the corresponding 3He/ 4He and 36Cl/Cl ratios are calculated. From a comparison of: (i) the 3He/ 4He ratios measured in the groundwater samples with the calculated in situ ratios in rocks and (ii) the measured δ 37Cl ratios with the 4He concentrations measured in groundwater it is concluded that both helium and chloride are most likely added to the aquifer from sources in the stagnant porewaters of the confining shale by diffusion and/or mixing. Based on this 'working hypothesis' the 36Cl transport equation in groundwater is solved taking into account: (i) radioactive decay, (ii) subsurface production in the sandstone aquifer (with an in situ 36Cl/Cl ratio of 6×10 -15) and (iii) addition of chloride from a source in the confining shale (with a 36Cl/Cl ratio of 13×10 -15). Lacking better information it is assumed that the chloride concentration increased linearly with time from an (unknown) initial value Ci to its measured present value C= Ci+ Ca, where Ca represents the (unknown) amount of chloride added from subsurface sources. Using the 81Kr ages of the four groundwater samples and a

  12. Measurement of 26Al in Iron Meteorites by Thermal Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Langellier, C.; Birck, J. L.; Allegre, C. J.

    1992-07-01

    We report here the measurement of ^26Al by thermal ionization mass spectrometry in iron meteorites. Nuclides produced by the interaction of galactic cosmic rays with meteoritic bodies are widely used to reconstruct the parental history of meteorites and also to address the problem of constancy of cosmic rays in the past. In iron meteorites the half life of ^26Al is much shorter than the exposure age and saturation is reached. Its concentration is then directly related to the preatmospheric shielding of the analyzed sample. It can be also used together, with other short-lived nuclides, to calculate the terrestrial residence time for found meteorites. Natural contents of ^26Al in iron meteorites are very small (a few dpm per kg) and have been measured earlier by counting techniques and AMS. For thermal ionization the difficulty resides mostly in the measurement of the ^26Al/^27Al ratio. ^27Al may be contained in the sample and also is introduced by the chemical separation. ^27Al beams of 10^-11 A are readily obtained with a few ng of aluminium and are measured on a standard faraday cup. ^26Al was measured on a low background electron multiplier operated in the ion counter mode. ^27Al content was measured by isotope dilution using a ^26Al spike. The ^26Al ion beam can be interfered by traces of ^26Mg. Usually the ^26Mg background could be brought lower than 10^-9 relative to ^27Al. This is sufficient for the present experiment. No organic interference was present at the same level. The abundance sensitivity stemming from the ^27Al beam on mass 26 is 3 10^-9. Results: Samples sizes for this study range from 100 to 300 mg of iron. Ratios are measured with a precision of about 1% thereby leading to a final ^26Al content with an accuracy around 2%. Two meteorites were investigated so far: Grant and Canyon Diablo. Grant is one of the best documented meteorites with regard to spallation effects. The result on Grant is an agreement with literature AMS data (Graf et al., 1987

  13. 26Al production: The Allende meteorite (Chihuahua) stellar nucleosynthesis and solar models

    NASA Astrophysics Data System (ADS)

    Araujo-Escalona, V.; Andrade, E.; Barrón-Palos, L.; Canto, C.; Favela, F.; Huerta, A.; de Lucio, O.; Ortiz, M. E.; Solís, C.; Chávez, E.

    2015-07-01

    In 1969 a meteorite fell near the small town of Allende, state of Chihuahua in the north of Mexico. Its study yielded information that changed the current understanding of the solar model. In particular traces of 26Al were found. Abundances of that isotope had been seen in the universe and were related to regions of active heavy nucleosynthesis. Its presence on the solar system was unexpected. It is now understood that cosmic rays induce nuclear reactions on materials to produce 26Al, on Earth this is well known and it is the basis of many environmental studies, so it is not only the product of some high metalicity star collapse. Taking advantage of the recently reinforced laboratory infrastructure of the Instituto de Física, at UNAM in Mexico City, we proposed to measure the cross section for 26Al production via some of the most likely reactions, from the nuclear physics point of view (highest Q-values). In this paper the study of the 28Si(d,α)26 Al nuclear reaction is shown. A target is prepared by a mixture of silicon and aluminum powders. It is irradiated with a deuteron beam (≈1 µA current) at the MV CN-Van de Graaff accelerator laboratory. The number of projectiles is deduced by Rutherford Backscattering Spectrometry (RBS). The produced 26Al nuclei are then counted at the Accelerator Mass Spectrometry Laboratory.

  14. {sup 26}Al production: The Allende meteorite (Chihuahua) stellar nucleosynthesis and solar models

    SciTech Connect

    Araujo-Escalona, V.; Andrade, E.; Barrón-Palos, L.; Canto, C.; Favela, F.; Huerta, A.; Lucio, O. de; Ortiz, M. E.; Solís, C.; Chávez, E.

    2015-07-23

    In 1969 a meteorite fell near the small town of Allende, state of Chihuahua in the north of Mexico. Its study yielded information that changed the current understanding of the solar model. In particular traces of {sup 26}Al were found. Abundances of that isotope had been seen in the universe and were related to regions of active heavy nucleosynthesis. Its presence on the solar system was unexpected. It is now understood that cosmic rays induce nuclear reactions on materials to produce {sup 26}Al, on Earth this is well known and it is the basis of many environmental studies, so it is not only the product of some high metalicity star collapse. Taking advantage of the recently reinforced laboratory infrastructure of the Instituto de Física, at UNAM in Mexico City, we proposed to measure the cross section for {sup 26}Al production via some of the most likely reactions, from the nuclear physics point of view (highest Q-values). In this paper the study of the {sup 28}Si(d,α){sup 26} Al nuclear reaction is shown. A target is prepared by a mixture of silicon and aluminum powders. It is irradiated with a deuteron beam (≈1 µA current) at the MV CN-Van de Graaff accelerator laboratory. The number of projectiles is deduced by Rutherford Backscattering Spectrometry (RBS). The produced {sup 26}Al nuclei are then counted at the Accelerator Mass Spectrometry Laboratory.

  15. Improvement of the 36Cl-AMS system at MALT using a Monte Carlo ion-trajectory simulation in a gas-filled magnet

    NASA Astrophysics Data System (ADS)

    Aze, Takahiro; Matsuzaki, Hiroyuki; Matsumura, Hiroshi; Nagai, Hisao; Fujimura, Masatsugu; Noguchi, Mayumi; Hongo, Yayoi; Yokoyama, Yusuke

    2007-06-01

    We developed and experimentally confirmed a Monte Carlo simulation code to describe the trajectories of 36Cl and 36S ions in a gas-filled magnet (GFM) at the MALT, the University of Tokyo. The simulation revealed that the central trajectories of the ions in the GFM are almost spiral and most of the 36S ions collided with the interior wall of the GFM. Based on this property of the trajectories, we have found a more advantageous condition for suppressing 36S. As a result, the background level of the 36Cl/Cl ratio was lowered to 10-15.

  16. Heterogeneous distribution of 26Al at the birth of the solar system: Evidence from refractory grains and inclusions

    NASA Astrophysics Data System (ADS)

    Krot, A. N.; Makide, K.; Nagashima, K.; Huss, G. R.; Ogliore, R. C.; Ciesla, F. J.; Yang, L.; Hellebrand, E.; Gaidos, E.

    2012-12-01

    Abstract-We review recent results on O- and Mg-isotope compositions of refractory grains (corundum, hibonite) and calcium, aluminum-rich inclusions (CAIs) from unequilibrated ordinary and carbonaceous chondrites. We show that these refractory objects originated in the presence of nebular gas enriched in 16O to varying degrees relative to the standard mean ocean water value: the Δ17OSMOW value ranges from approximately -16‰ to -35‰, and recorded heterogeneous distribution of <span class="hlt">26</span><span class="hlt">Al</span> in their formation region: the inferred (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 ranges from approximately 6.5 × 10-5 to <2 × 10-6. There is no correlation between O- and Mg-isotope compositions of the refractory objects: <span class="hlt">26</span><span class="hlt">Al</span>-rich and <span class="hlt">26</span><span class="hlt">Al</span>-poor refractory objects have similar O-isotope compositions. We suggest that <span class="hlt">26</span><span class="hlt">Al</span> was injected into the <span class="hlt">26</span><span class="hlt">Al</span>-poor collapsing protosolar molecular cloud core, possibly by a wind from a neighboring massive star, and was later homogenized in the protoplanetary disk by radial mixing, possibly at the canonical value of <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio (approximately 5 × 10-5). The <span class="hlt">26</span><span class="hlt">Al</span>-rich and <span class="hlt">26</span><span class="hlt">Al</span>-poor refractory grains and inclusions represent different generations of refractory objects, which formed prior to and during the injection and homogenization of <span class="hlt">26</span><span class="hlt">Al</span>. Thus, the duration of formation of refractory grains and CAIs cannot be inferred from their <span class="hlt">26</span><span class="hlt">Al</span>-26Mg systematics, and the canonical (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 does not represent the initial abundance of <span class="hlt">26</span><span class="hlt">Al</span> in the solar system; instead, it may or may not represent the average abundance of <span class="hlt">26</span><span class="hlt">Al</span> in the fully formed disk. The latter depends on the formation time of CAIs with the canonical <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio relative to the timing of complete delivery of stellar <span class="hlt">26</span><span class="hlt">Al</span> to the solar system, and the degree of its subsequent homogenization in the disk. The injection of material containing <span class="hlt">26</span><span class="hlt">Al</span> resulted in no observable changes in O-isotope composition of the solar system. Instead, the variations in O-isotope compositions between individual</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.192..279H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.192..279H"><span id="translatedtitle">Characterization of a diffusion-dominant system using chloride and chlorine isotopes (<span class="hlt">36</span><span class="hlt">Cl</span>, 37Cl) for the confining layer of the Great Artesian Basin, Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hasegawa, Takuma; Nakata, Kotaro; Mahara, Yasunori; Habermehl, M. A.; Oyama, Takahiro; Higashihara, Tomohiro</p> <p>2016-11-01</p> <p>The Great Artesian Basin (GAB), Australia, one of the largest confined aquifer systems in the world, attracts great attention for groundwater dating. However, there is little information about the confining layers. Therefore, core drilling investigations were conducted to characterize the main confining layer using chloride (Cl) and chlorine isotopes (<span class="hlt">36</span><span class="hlt">Cl</span>, 37Cl) at Marree (South Australia) and Richmond (Queensland), which are near the discharge and recharge areas in the GAB, respectively. Pore water samples were collected from rock cores by squeezing and leaching. The Cl concentration, <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio, and δ37Cl value in the confining layer decreased with depth at both Marree and Richmond. The <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios at the shallower part of the confining layer are significantly higher than the in situ secular equilibrium (<span class="hlt">36</span><span class="hlt">Cl</span>/Clse) calculated from the chemical compositions of the rock. The <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio logarithmically decreased with depth. The calculated <span class="hlt">36</span><span class="hlt">Cl</span>/Clse is equivalent to the lowest <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio at Richmond. In contrast, the <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios at Marree are higher than the calculated <span class="hlt">36</span><span class="hlt">Cl</span>/Clse. The <span class="hlt">36</span><span class="hlt">Cl</span>/Clse was reached at Richmond, but not at Marree. This probably reflects the transport time due to the difference in diffusion coefficients. The δ37Cl value becomes more negative toward the deeper levels, reaching -4.5‰ and -6.1‰ at Marree and Richmond, respectively. These results suggest that the Cl is of meteoric origin and is transported by diffusion in the confining layer. Analytical simulations using diffusion equations were conducted to reproduce excess <span class="hlt">36</span><span class="hlt">Cl</span> (36Clex), Cl, and δ37Cl. The 36Clex profile, which logarithmically decreased with depth, was reproduced by steady-state diffusion equations with radioactive decay, and the diffusion coefficients derived from the 36Clex profile were equivalent to those from the laboratory experiments. A grid-search simulation using an unsteady-state diffusion equation was conducted to reproduce the Cl and δ37Cl</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010ApJ...719L..99L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010ApJ...719L..99L"><span id="translatedtitle">Lithium-Beryllium-Boron Isotopic Compositions in Meteoritic Hibonite: Implications for Origin of <span class="hlt">10</span><span class="hlt">Be</span> and Early Solar System Irradiation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Ming-Chang; Nittler, Larry R.; Alexander, Conel M. O'D.; Lee, Typhoon</p> <p>2010-08-01</p> <p>NanoSIMS isotopic measurements of Li, Be, and B in individual hibonite grains extracted from the Murchison meteorite revealed that 10B excesses correlate with the 9Be/11B ratios in <span class="hlt">26</span><span class="hlt">Al</span>-free PLAty hibonite Crystals. From these data, an initial <span class="hlt">10</span><span class="hlt">Be</span>/9Be = (5.5 ± 1.6) × 10-4 (2σ) and 10B/11B = 0.2508 ± 0.0015 can be inferred. On the other hand, chondritic boron isotopic compositions were found in <span class="hlt">26</span><span class="hlt">Al</span>-bearing Spinel-HIBonite spherules, most likely due to contamination with normal boron. No 7Li excesses due to 7Be decay were observed. When combined with previously reported data, the new data yield the best defined <span class="hlt">10</span><span class="hlt">Be</span>/9Be = (5.3 ± 1.0) × 10-4 (2σ) and 10B/11B = 0.2513 ± 0.0012 for PLACs. A comparison of this value and the best constrained <span class="hlt">10</span><span class="hlt">Be</span>/9Be = (8.8 ± 0.6) × 10-4 in CV Ca-Al-rich inclusions supports a heterogeneous distribution of <span class="hlt">10</span><span class="hlt">Be</span> and its protosolar irradiation origin. We consider two possible irradiation scenarios that could potentially lead to the observed Li-Be-B isotopic compositions in PLACs. Although in situ irradiation of solids with hibonite chemistry seems to provide the simplest explanation, more high quality data will be needed for quantitatively constraining the irradiation history.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4946628','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4946628"><span id="translatedtitle">Early accretion of protoplanets inferred from a reduced inner solar system <span class="hlt">26</span><span class="hlt">Al</span> inventory</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Schiller, Martin; Connelly, James N.; Glad, Aslaug C.; Mikouchi, Takashi; Bizzarro, Martin</p> <p>2016-01-01</p> <p>The mechanisms and timescales of accretion of 10–1000 km sized planetesimals, the building blocks of planets, are not yet well understood. With planetesimal melting predominantly driven by the decay of the short-lived radionuclide <span class="hlt">26</span><span class="hlt">Al</span> (26Al→26Mg; t1/2 = 0.73 Ma), its initial abundance determines the permissible timeframe of planetesimal-scale melting and its subsequent cooling history. Currently, precise knowledge about the initial <span class="hlt">26</span><span class="hlt">Al</span> abundance [(<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0] exists only for the oldest known solids, calcium aluminum-rich inclusions (CAIs) – the so-called canonical value. We have determined the <span class="hlt">26</span><span class="hlt">Al</span>/27Al of three angrite meteorites, D’Orbigny, Sahara 99555 and NWA 1670, at their time of crystallization, which corresponds to (3.98 ± 0.15)×10−7, (3.64 ± 0.18)×10−7, and (5.92 ± 0.59)×10−7, respectively. Combined with a newly determined absolute U-corrected Pb–Pb age for NWA 1670 of 4564.39 ± 0.24 Ma and published U-corrected Pb–Pb ages for the other two angrites, this allows us to calculate an initial (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 of (1.33−0.18+0.21)×10−5 for the angrite parent body (APB) precursor material at the time of CAI formation, a value four times lower than the accepted canonical value of 5.25 × 10−5. Based on their similar 54Cr/52Cr ratios, most inner solar system materials likely accreted from material containing a similar <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio as the APB precursor at the time of CAI formation. To satisfy the abundant evidence for widespread planetesimal differentiation, the subcanonical <span class="hlt">26</span><span class="hlt">Al</span> budget requires that differentiated planetesimals, and hence protoplanets, accreted rapidly within 0.25 ± 0.15 Ma of the formation of canonical CAIs. PMID:27429474</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16151825','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16151825"><span id="translatedtitle">The Hiroshima thermal-neutron discrepancy for (<span class="hlt">36</span>)<span class="hlt">Cl</span> at large distances. Part II: Natural in situ production as a source.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nolte, Eckehart; Huber, Thomas; Rühm, Werner; Kato, Kazuo; Lazarev, Vitali; Schultz, Ludolf</p> <p>2005-10-01</p> <p>For Hiroshima, a large discrepancy between calculated and measured thermal-neutron fluences had been reported in the past, for distances to the epicenter larger than about 1,000 m. To be more specific, measured (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentrations in environmental samples from Hiroshima were too large at these distances, and the ratio of measured to calculated values reached about 70, at a distance of 1,800 m. In an attempt to identify other sources that might also produce (<span class="hlt">36</span>)<span class="hlt">Cl</span> in Hiroshima samples, the role of cosmic rays and of neutrons from natural terrestrial sources was investigated. Four reaction mechanisms were taken into account: spallation reactions of the nucleonic (hadronic) component of the cosmic rays on potassium (K) and calcium (Ca) in the sample material, particle emission after nuclear capture of negative muons by K and Ca, reactions of fast-muon induced electromagnetic, and hadronic showers with K and Ca, and neutron capture reactions with (35)Cl in the sample where the neutrons originate from the above three reaction mechanisms and from uranium and thorium decay. These mechanisms are physically described and mathematically quantified. It is shown that among those parameters important for the production of (<span class="hlt">36</span>)<span class="hlt">Cl</span> in granite, the chemical composition of the sample, the depth in the quarry where the sample had initially been taken, and the erosion rate at the site of the quarry are most important. Based on these physical, chemical, and geological parameters, (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentrations were calculated for different types of granite that are typical for the Hiroshima area. In samples that were of these granite types and that had not been exposed to atomic bomb(A-bomb) neutrons, the (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentration was also determined experimentally by means of accelerator mass spectrometry, and good agreement was found with the calculated values. The (<span class="hlt">36</span>)<span class="hlt">Cl</span> signal due to natural in situ production was also calculated in granite samples that had been exposed to A-bomb neutrons at</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16151825','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16151825"><span id="translatedtitle">The Hiroshima thermal-neutron discrepancy for (<span class="hlt">36</span>)<span class="hlt">Cl</span> at large distances. Part II: Natural in situ production as a source.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nolte, Eckehart; Huber, Thomas; Rühm, Werner; Kato, Kazuo; Lazarev, Vitali; Schultz, Ludolf</p> <p>2005-10-01</p> <p>For Hiroshima, a large discrepancy between calculated and measured thermal-neutron fluences had been reported in the past, for distances to the epicenter larger than about 1,000 m. To be more specific, measured (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentrations in environmental samples from Hiroshima were too large at these distances, and the ratio of measured to calculated values reached about 70, at a distance of 1,800 m. In an attempt to identify other sources that might also produce (<span class="hlt">36</span>)<span class="hlt">Cl</span> in Hiroshima samples, the role of cosmic rays and of neutrons from natural terrestrial sources was investigated. Four reaction mechanisms were taken into account: spallation reactions of the nucleonic (hadronic) component of the cosmic rays on potassium (K) and calcium (Ca) in the sample material, particle emission after nuclear capture of negative muons by K and Ca, reactions of fast-muon induced electromagnetic, and hadronic showers with K and Ca, and neutron capture reactions with (35)Cl in the sample where the neutrons originate from the above three reaction mechanisms and from uranium and thorium decay. These mechanisms are physically described and mathematically quantified. It is shown that among those parameters important for the production of (<span class="hlt">36</span>)<span class="hlt">Cl</span> in granite, the chemical composition of the sample, the depth in the quarry where the sample had initially been taken, and the erosion rate at the site of the quarry are most important. Based on these physical, chemical, and geological parameters, (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentrations were calculated for different types of granite that are typical for the Hiroshima area. In samples that were of these granite types and that had not been exposed to atomic bomb(A-bomb) neutrons, the (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentration was also determined experimentally by means of accelerator mass spectrometry, and good agreement was found with the calculated values. The (<span class="hlt">36</span>)<span class="hlt">Cl</span> signal due to natural in situ production was also calculated in granite samples that had been exposed to A-bomb neutrons at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11539739','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11539739"><span id="translatedtitle">Radiogenic heating of comets by <span class="hlt">26</span><span class="hlt">Al</span> and implications for their time of formation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Prialnik, D; Bar-Nun, A; Podolak, M</p> <p>1987-08-15</p> <p>The effect of radiogenic heating on the thermal evolution of spherical icy bodies with radii 1 km < R < 100 km was investigated. The radioisotopes considered were <span class="hlt">26</span><span class="hlt">Al</span>, 40K, 232Th, 235U, and 238U. Except for the <span class="hlt">26</span><span class="hlt">Al</span> abundance, which was varied, the other initial abundances were kept fixed, at values derived from those of chondritic meteorites and corresponding to a gas-to-dust ratio of 1. The initial models were homogeneous and isothermal (To = 10 K) amorphous ice spheres, in a circular orbit at 10(4) AU from the Sun. The main object of this study was to examine the conditions under which the transition temperature from amorphous into cubic ice (Ta = 137 K) would be reached. It was shown that the influence of the short-lived radionuclide <span class="hlt">26</span><span class="hlt">Al</span> dominates the effect of other radioactive species for bodies of radii up to approximately 50 km. Consequently, if we require comets to retain their ice in amorphous form, as suggested by observations, an upper limit of approximately 4 x 10(-9) is obtained for the initial <span class="hlt">26</span><span class="hlt">Al</span> abundance in comets, a factor of 100 lower than that of the inclusions in the Allende meteorite. A lower limit for the formation time of comets may thus be derived. The possibility of a coexistence of molten cometary cores and extended amorphous ice mantles is ruled out. Larger icy spheres (R > 100 km) reached Ta even in the absence of <span class="hlt">26</span><span class="hlt">Al</span>, due to the decay of the other radionuclides. As a result, a crystalline core formed whose relative size depended on the composition assumed. Thus the outermost icy satellites in the solar system, which might have been formed of ice in the amorphous state, have probably undergone crystallization and may have exhibited eruptive activity when the gas trapped in the amorphous ice was released (e.g., Miranda).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014QSRv...90..106Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014QSRv...90..106Z"><span id="translatedtitle">Mid-Holocene cluster of large-scale landslides revealed in the Southwestern Alps by <span class="hlt">36</span><span class="hlt">Cl</span> dating. Insight on an Alpine-scale landslide activity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zerathe, Swann; Lebourg, Thomas; Braucher, Régis; Bourlès, Didier</p> <p>2014-04-01</p> <p>Although it is generally assumed that the internal structure of a slope (e.g. lithology and rock mass properties, inherited faults and heterogeneities, etc.) is preponderant for the progressive development of large-scale landslides, the ability to identify triggering factors responsible for final slope failures such as glacial debuttressing, seismic activities or climatic changes, especially when considering landslide cluster at an orogen-scale, is still debated. Highlighting in this study the spatial and temporal concordant clustering of deep-seated slope failures in the external Southwestern Alps, we discuss and review the possible causes for such wide-spread slope instabilities at both local and larger (Alpine) scale. High resolution field mapping coupled with electrical resistivity tomography first allows establishing an inventory of large landslides in the Southwestern Alps, determining their structural model, precising their depth limit (100-200 m) as well as the involved rock volumes (>107 m3). We show that they developed in the same geostructural context of thick mudstone layers overlain by faulted limestone and followed a block-spread model of deformation that could evolve in rock-collapse events. Cosmic ray exposure dating (CRE), using both <span class="hlt">36</span><span class="hlt">Cl</span> and <span class="hlt">10</span><span class="hlt">Be</span> in coexisting limestone and chert, respectively, has been carried out from the main scarps of six Deep Seated Landslides (DSL) and leads to landslide-failure CRE ages ranging from 3.7 to 4.7 ka. They highlighted: (i) mainly single and fast ruptures and (ii) a possible concomitant initiation with a main peak of activity between 3.3 and 5.1 ka, centered at ca 4.2 ka. Because this region was not affected by historical glaciations events, landslide triggering by glacial unloading can be excluded. The presented data combined with field observations preferentially suggest that these failures were climatically driven and were most likely controlled by high pressure changes in the karstic medium. In effect, the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.C13A0602W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.C13A0602W"><span id="translatedtitle">Cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> and Paleoaccumulation Rates at WAIS Divide from 12-19 kyr BP</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Welten, K. C.; Woodruff, T. E.; Caffee, M. W.</p> <p>2012-12-01</p> <p>Concentrations of cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> in polar ice samples are affected by variations in solar activity, geomagnetic field strength, atmospheric mixing and annual snow accumulation rates. We are presently engaged in a study to obtain a continuous <span class="hlt">10</span><span class="hlt">Be</span> record in a deep ice core (WDC06A) that was drilled at the West Antarctic Ice Sheet (WAIS) Divide, a site with an average snow accumulation rate of ~20 cm weq/yr, similar to the GISP2 site in Greenland. We previously reported <span class="hlt">10</span><span class="hlt">Be</span> in annual layers in the top 114 m of WDC06A (Woodruff et al. 2011) and <span class="hlt">10</span><span class="hlt">Be</span> and <span class="hlt">36</span><span class="hlt">Cl</span> at decadal resolution in the top 560 m (Welten et al. 2009), and are now measuring <span class="hlt">10</span><span class="hlt">Be</span> in samples from a depth of 1800-2500 m, corresponding to preliminary ages of 10-20 kyr BP. We separated <span class="hlt">10</span><span class="hlt">Be</span> from ice samples of 300-600 g, following procedures described previously (Finkel and Nishiizumi 1997) and measured <span class="hlt">10</span><span class="hlt">Be</span> concentrations by accelerator mass spectrometry at PRIME lab. So far, we measured <span class="hlt">10</span><span class="hlt">Be</span> in 50 ice samples with ages between 12.3-13.9 kyr BP, at a resolution of ~30 yr/sample, and 50 samples from 15.6-19.0 kyr BP at an average resolution of ~70 yr/sample. The <span class="hlt">10</span><span class="hlt">Be</span> depth profile shows a relative constant value of (28 ± 3) x 10^3 atoms/g for samples younger than 18 kyr BP and a value of (41 ± 3) x 10^3 atoms/g for ice from 18.2-19.0 kyr BP. These values are 50-120% higher than the average concentration of 18.4 x 10^3 atoms/g for WAIS Divide ice samples from the last 420 year of snow accumulation. Although the higher <span class="hlt">10</span><span class="hlt">Be</span> concentrations in ice from the last glacial stage can be partly attributed to a 10-20% lower geomagnetic field strength (and thus a higher global <span class="hlt">10</span><span class="hlt">Be</span> production rate), they are mainly due to lower snow accumulation rates during the last glacial stage. After applying corrections for changes in geomagnetic field strength based on the SINT-800 record, we derive average snow accumulation rates of 13-15 cm weq/yr for the age interval of 12-18 kyr BP and of ~10 cm weq/yr for 18.2-19.0 kyr</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...826...22K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...826...22K"><span id="translatedtitle">Tracking the Distribution of <span class="hlt">26</span><span class="hlt">Al</span> and 60Fe during the Early Phases of Star and Disk Evolution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuffmeier, Michael; Frostholm Mogensen, Troels; Haugbølle, Troels; Bizzarro, Martin; Nordlund, Åke</p> <p>2016-07-01</p> <p>The short-lived <span class="hlt">26</span><span class="hlt">Al</span> and 60Fe radionuclides are synthesized and expelled into the interstellar medium by core-collapse supernova events. The solar system’s first solids, calcium-aluminum refractory inclusions (CAIs), contain evidence for the former presence of the <span class="hlt">26</span> <span class="hlt">Al</span> nuclide defining the canonical <span class="hlt">26</span><span class="hlt">Al</span>/27 Al ratio of ˜ 5× {10}-5. A different class of objects temporally related to canonical CAIs are CAIs with fractionation and unidentified nuclear effects (FUN CAIs), which record a low initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al of 10-6. The contrasting level of <span class="hlt">26</span><span class="hlt">Al</span> between these objects is often interpreted as reflecting the admixing of the <span class="hlt">26</span><span class="hlt">Al</span> nuclides during the early formative phase of the Sun. We use giant molecular cloud scale adaptive mesh-refinement numerical simulations to trace the abundance of <span class="hlt">26</span><span class="hlt">Al</span> and 60Fe in star-forming gas during the early stages of accretion of individual low-mass protostars. We find that the <span class="hlt">26</span><span class="hlt">Al</span>/27Al and 60Fe/56Fe ratios of accreting gas within a vicinity of 1000 au of the stars follow the predicted decay curves of the initial abundances at the time of star formation without evidence of spatial or temporal heterogeneities for the first 100 kyr of star formation. Therefore, the observed differences in <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios between FUN and canonical CAIs are likely not caused by admixing of supernova material during the early evolution of the proto-Sun. Selective thermal processing of dust grains is a more viable scenario to account for the heterogeneity in <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios at the time of solar system formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22130650','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22130650"><span id="translatedtitle">ABUNDANCE OF {sup <span class="hlt">26</span>}<span class="hlt">Al</span> AND {sup 60}Fe IN EVOLVING GIANT MOLECULAR CLOUDS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Vasileiadis, Aristodimos; Nordlund, Ake; Bizzarro, Martin</p> <p>2013-05-20</p> <p>The nucleosynthesis and ejection of radioactive {sup <span class="hlt">26</span>}<span class="hlt">Al</span> (t{sub 1/2} {approx} 0.72 Myr) and {sup 60}Fe, (t{sub 1/2} {approx} 2.5 Myr) into the interstellar medium is dominated by the stellar winds of massive stars and supernova type II explosions. Studies of meteorites and their components indicate that the initial abundances of these short-lived radionuclides in the solar protoplanetary disk were higher than the background levels of the galaxy inferred from {gamma}-ray astronomy and models of the galactic chemical evolution. This observation has been used to argue for a late-stage addition of stellar debris to the solar system's parental molecular cloud or, alternatively, the solar protoplanetary disk, thereby requiring a special scenario for the formation of our solar system. Here, we use supercomputers to model-from first principles-the production, transport, and admixing of freshly synthesized {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup 60}Fe in star-forming regions within giant molecular clouds. Under typical star formation conditions, the levels of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> in most star-forming regions are comparable to that deduced from meteorites, suggesting that the presence of short-lived radionuclides in the early solar system is a generic feature of the chemical evolution of giant molecular clouds. The {sup 60}Fe/{sup <span class="hlt">26</span>}<span class="hlt">Al</span> yield ratio of Almost-Equal-To 0.2 calculated from our simulations is consistent with the galactic value of 0.15 {+-} 0.06 inferred from {gamma}-ray astronomy but is significantly higher than most current solar system measurements indicate. We suggest that estimates based on differentiated meteorites and some chondritic components may not be representative of the initial {sup 60}Fe abundance of the bulk solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997NIMPB.123..259K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997NIMPB.123..259K"><span id="translatedtitle">Investigations of the human aluminium biokinetics with <span class="hlt">26</span><span class="hlt">Al</span> and AMS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kislinger, G.; Steinhausen, C.; Alvarez-Brückmann, M.; Winklhofer, C.; Ittel, T.-H.; Nolte, E.</p> <p>1997-03-01</p> <p>Continuing the investigations on two healthy volunteers and on two patients with renal failure, the aluminium biokinetics in humans was studied by administering oral and intravenous doses of <span class="hlt">26</span><span class="hlt">Al</span> to three further healthy volunteers. Blood samples were drawn at times between 20 min and half a year after administration of the doses. The complete daily urine was collected during the first nine days, spot urine samples were taken at later times when blood samples were obtained. Creatinin renal clearances and haematocrit values were also obtained in the time period of the investigations. The <span class="hlt">26</span><span class="hlt">Al</span> concentrations of the samples were measured using the Munich Tandem accelerator. An open compartment model was developed to describe the time dependences of the measured <span class="hlt">26</span><span class="hlt">Al</span> concentrations in blood and urine and to establish the human Al biokinetics. The model comprises stomach and duodenum for oral administration, a central compartment consisting of blood plasma and interstitial fluid with transferrin and citrate binding and three peripheral compartments which are needed to describe the time dependence for the long observation period of up to three years. Excretion of Al was mainly described from plasma citrate via the kidneys into the urine and to a lesser extent from the plasma transferrin via the liver into the stool. Time constants between the compartments, fractional intestinal absorption factors and aluminium renal clearances were derived. It was found that the sizes of two peripheral compartments of the patients with renal failure were different to those of the healthy volunteers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.176..295L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.176..295L"><span id="translatedtitle">Accretion timescales and style of asteroidal differentiation in an <span class="hlt">26</span><span class="hlt">Al</span>-poor protoplanetary disk</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Larsen, K. K.; Schiller, M.; Bizzarro, M.</p> <p>2016-03-01</p> <p>The decay of radioactive <span class="hlt">26</span><span class="hlt">Al</span> to 26Mg (half-life of 730,000 years) is postulated to have been the main energy source promoting asteroidal melting and differentiation in the nascent solar system. High-resolution chronological information provided by the <span class="hlt">26</span><span class="hlt">Al</span>-26Mg decay system is, therefore, intrinsically linked to the thermal evolution of early-formed planetesimals. In this paper, we explore the timing and style of asteroidal differentiation by combining high-precision Mg isotope measurements of meteorites with thermal evolution models for planetesimals. In detail, we report Mg isotope data for a suite of olivine-rich [Al/Mg ∼ 0] achondritic meteorites, as well as a few chondrites. Main Group, pyroxene and the Zinder pallasites as well as the lodranite all record deficits in the mass-independent component of μ26Mg (μ26Mg∗) relative to chondrites and Earth. This isotope signal is expected for the retarded ingrowth of radiogenic 26Mg∗ in olivine-rich residues produced through partial silicate melting during <span class="hlt">26</span><span class="hlt">Al</span> decay and consistent with their marginally heavy Mg isotope composition relative to ordinary chondrites, which may reflect the early extraction of isotopically light partial melts from the source rock. We propose that their parent planetesimals started forming within ∼250,000 years of solar system formation from a hot (>∼500 K) inner protoplanetary disk region characterized by a reduced initial (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 abundance (∼1-2 × 10-5) relative to the (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 value in CAIs of 5.25 × 10-5. This effectively reduced the total heat production and allowed for the preservation of solid residues produced through progressive silicate melting with depth within the planetesimals. These 'non-carbonaceous' planetesimals acquired their mass throughout an extended period (>3 Myr) of continuous accretion, thereby generating onion-shell structures of incompletely differentiated zones, consisting of olivine-rich residues, overlaid by metachondrites and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1816190M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1816190M"><span id="translatedtitle">The rock avalanche of the Mt. Peron (Eastern Alps, Italy): new insights from <span class="hlt">36</span><span class="hlt">Cl</span> exposure dating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin, Silvana; Ivy-ochs, Susan; Alfimov, Vasili; Vockenhuber, %Christof; Surian, Nicola; Campedel, Paolo; Rigo, Manuel; Viganò, Alfio; De Zorzi, Manuel</p> <p>2016-04-01</p> <p>In the Late Pleistocene, in the southern side of the Eastern Alps (Veneto region, Italy), when the glacier tongues retreated from the end moraine system areas towards the Dolomitic region, large rock avalanches took place. In the Belluno Valley, occupied by the Piave river, the left side is represented by the Belluno Prealps range, corresponding to the northern flank of a km-scale WSW-ENE oriented alpine syncline formed by rocks from Late Triassic to Late Tertiary in age. The Mt. Peron, belonging to this mountain range, shows its southern lower slope covered by debris cones with scattered boulders and its higher slope, corresponding to the scarp, made of vertical rock strata. At the foot of Mt. Peron, at a distance varying from 500 to 4500 m, there is a 4.5 km2 fan like area delimited by a perimeter of about 15 km. This is a hilly area of poortly sorted, chaotic deposits composed of heterogeneous debris, sandy and silty gravels, angular blocks and very large boulders of carbonatic rocks up to 20 m in diameter. The average thickness of the deposit was estimated to be 80 m, with maximum of 120 m. According to previous works, the main event occurred during the first phases of deglaciation, between 17,000 and 15,000 years BP. Popular stories narrate about two legendary villages destroyed by a mass of stones rolling down in the valley. This is confirmed by archeological findings in the Piave valley which indicate the presence of almost one pre-historic settlement dating 40000-20000 years a B.P., (i.e. before the Last Glacial Maximum).. Recent <span class="hlt">36</span><span class="hlt">Cl</span> exposure dating have yielded historical ages for both the boulders at the foot of the Mt Peron and those located a few km far from the main scarp. According to these exposure ages we can not exclude the hypothesis that earthquakes related to the Venetian faults could have played a key role for triggering of the rock avalanche and that the main gravitational event took place in historical times rather than during the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015GGG....16.2812V&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015GGG....16.2812V&link_type=ABSTRACT"><span id="translatedtitle">Late Pleistocene ages for the most recent volcanism and glacial-pluvial deposits at Big Pine volcanic field, California, USA, from cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> dating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vazquez, J. A.; Woolford, J. M.</p> <p>2015-09-01</p> <p>The Big Pine volcanic field is one of several Quaternary volcanic fields that poses a potential volcanic hazard along the tectonically active Owens Valley of east-central California, and whose lavas are interbedded with deposits from Pleistocene glaciations in the Sierra Nevada Range. Previous geochronology indicates an ˜1.2 Ma history of volcanism, but the eruption ages and distribution of volcanic products associated with the most-recent eruptions have been poorly resolved. To delimit the timing and products of the youngest volcanism, we combine field mapping and cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> dating of basaltic lava flows in the area where lavas with youthful morphology and well-preserved flow structures are concentrated. Field mapping and petrology reveal approximately 15 vents and 6 principal flow units with variable geochemical composition and mineralogy. Cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages for lava flow units from the top, middle, and bottom of the volcanic stratigraphy indicate eruptions at ˜17, 27, and 40 ka, revealing several different and previously unrecognized episodes of late Pleistocene volcanism. Olivine to plagioclase-pyroxene phyric basalt erupted from several vents during the most recent episode of volcanism at ˜17 ka, and produced a lava flow field covering ˜35 km2. The late Pleistocene <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages indicate that moraine and pluvial shoreline deposits that overlie or modify the youngest Big Pine lavas reflect Tioga stage glaciation in the Sierra Nevada and the shore of paleo-Owens Lake during the last glacial cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70157344','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70157344"><span id="translatedtitle">Late Pleistocene ages for the most recent volcanism and glacial-pluvial deposits at Big Pine volcanic field, California, USA, from cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> dating</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Vazquez, Jorge A.; Woolford, Jeff M</p> <p>2015-01-01</p> <p>The Big Pine volcanic field is one of several Quaternary volcanic fields that poses a potential volcanic hazard along the tectonically active Owens Valley of east-central California, and whose lavas are interbedded with deposits from Pleistocene glaciations in the Sierra Nevada Range. Previous geochronology indicates an ∼1.2 Ma history of volcanism, but the eruption ages and distribution of volcanic products associated with the most-recent eruptions have been poorly resolved. To delimit the timing and products of the youngest volcanism, we combine field mapping and cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> dating of basaltic lava flows in the area where lavas with youthful morphology and well-preserved flow structures are concentrated. Field mapping and petrology reveal approximately 15 vents and 6 principal flow units with variable geochemical composition and mineralogy. Cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages for lava flow units from the top, middle, and bottom of the volcanic stratigraphy indicate eruptions at ∼17, 27, and 40 ka, revealing several different and previously unrecognized episodes of late Pleistocene volcanism. Olivine to plagioclase-pyroxene phyric basalt erupted from several vents during the most recent episode of volcanism at ∼17 ka, and produced a lava flow field covering ∼35 km2. The late Pleistocene <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages indicate that moraine and pluvial shoreline deposits that overlie or modify the youngest Big Pine lavas reflect Tioga stage glaciation in the Sierra Nevada and the shore of paleo-Owens Lake during the last glacial cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4950964','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4950964"><span id="translatedtitle">Accretion timescales and style of asteroidal differentiation in an <span class="hlt">26</span><span class="hlt">Al</span>-poor protoplanetary disk</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Larsen, K.K.; Schiller, M.; Bizzarro, M.</p> <p>2016-01-01</p> <p>The decay of radioactive <span class="hlt">26</span><span class="hlt">Al</span> to 26Mg (half-life of 730,000 years) is postulated to have been the main energy source promoting asteroidal melting and differentiation in the nascent solar system. High-resolution chronological information provided by the 26Al−26Mg decay system is, therefore, intrinsically linked to the thermal evolution of early-formed planetesimals. In this paper, we explore the timing and style of asteroidal differentiation by combining high-precision Mg isotope measurements of meteorites with thermal evolution models for planetesimals. In detail, we report Mg isotope data for a suite of olivine-rich [Al/Mg ~ 0] achondritic meteorites, as well as a few chondrites. Main Group, pyroxene and the Zinder pallasites as well as the lodranite all record deficits in the mass-independent component of μ26Mg (μ26Mg*) relative to chondrites and Earth. This isotope signal is expected for the retarded ingrowth of radiogenic 26Mg* in olivine-rich residues produced through partial silicate melting during <span class="hlt">26</span><span class="hlt">Al</span> decay and consistent with their marginally heavy Mg isotope composition relative to ordinary chondrites, which may reflect the early extraction of isotopically light partial melts from the source rock. We propose that their parent planetesimals started forming within ~250,000 years of solar system formation from a hot (>~500 K) inner protoplanetary disk region characterized by a reduced initial (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 abundance (~1–2 × 10−5) relative to the (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 value in CAIs of 5.25 × 10−5. This effectively reduced the total heat production and allowed for the preservation of solid residues produced through progressive silicate melting with depth within the planetesimals. These ‘non-carbonaceous’ planetesimals acquired their mass throughout an extended period (>3 Myr) of continuous accretion, thereby generating onion-shell structures of incompletely differentiated zones, consisting of olivine-rich residues, overlaid by metachondrites and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.P32A..01C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.P32A..01C"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span> in the Saturnian System - New Interior Models for the Saturnian satellites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Castillo, J. C.; Matson, D. L.; Johnson, T. V.; Lunine, J. I.; McCord, T. B.; Sotin, C.; Thomas, P. C.; Turtle, E. B.</p> <p>2005-12-01</p> <p>Recent study of Iapetus' spin rate evolution highlights the need to form this satellite between between 1.0+/- 0.2 to 1.6+/- 0.4 My after the production of Calcium-Aluminum Inclusions (CAIs). We study the implications of this time constraint on the thermal evolution of other "icy" Saturnian satellites, assuming that they formed at the same time as Iapetus and from the same rocky material in proportion to their densities. Heat provided by <span class="hlt">26</span><span class="hlt">Al</span> decay contributes to partial to full melting and thus differentiation of all Saturn's medium-sized satellites, except Tethys. We also consider the effect of silicate hydration on the internal and geological evolution of these satellites. These results are compared with classical models (that do not include short-lived radiogenic species), in the light of the observational constraints available for these satellites. Including <span class="hlt">26</span><span class="hlt">Al</span> decay in the heat budget of the satellites allows to explain the observation of geological activity in silicate-poor satellites such as Tethys. We note that in Enceladus and Titan conditions might have been such that the boiling point of water was reached and water might have been lost very early in the history of these satellites. This opens the door to some explanation for the variations in density within the Saturnian system. Part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NIMPB.361..548Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..548Z"><span id="translatedtitle">Recent progress of <span class="hlt">10</span><span class="hlt">Be</span> tracer studies in Chinese loess</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, Weijian; Xie, Xingjun; Beck, Warren; Kong, Xianghui; Xian, Feng; Du, Yajuan; Wu, Zhenkun</p> <p>2015-10-01</p> <p>Studies of cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> in Chinese loess began about twenty-five years ago and since then a number of research groups worldwide have contributed to a firm understanding of the production, transport, deposition and storage of <span class="hlt">10</span><span class="hlt">Be</span> in loess. The essential characteristics that make <span class="hlt">10</span><span class="hlt">Be</span> a useful isotopic tracer in loess, include: (1) dominant atmospheric production directly linked to the intensity of the Earth's magnetic field; (2) climate-dependent deposition; and (3) subsequent immobility, so that as <span class="hlt">10</span><span class="hlt">Be</span> accumulates in a loess profile its stratigraphic integrity is preserved. This fact, combined with very high deposition rates in loess on the Chinese Loess Plateau, makes <span class="hlt">10</span><span class="hlt">Be</span> an especially valuable continental archive of paleoclimate and paleomagnetism, complementing marine and ice-core records. Here we provide in particular the most recent progress of <span class="hlt">10</span><span class="hlt">Be</span> tracer studies in Chinese loess, including the determination of the correct age of the Brunhes-Matuyama polarity reversal at 780 ± 3 ka B.P., in accord with marine and ice records, and quantitative reconstruction of 130-ka paleoprecipitation using <span class="hlt">10</span><span class="hlt">Be</span> from Chinese loess profiles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70015053','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70015053"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> distribution in soils from Merced River terraces, California</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Pavich, M.J.; Brown, L.; Harden, J.; Klein, J.; Middleton, R.</p> <p>1986-01-01</p> <p>The distribution and residence time of cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> in clay-rich soil horizons is fundamental to understanding and modelling the migration of <span class="hlt">10</span><span class="hlt">Be</span> on terrestrial sediments and in groundwater solutions. We have analyzed seven profiles of clay-rich soils developed from terrace sediments of the Merced River, California. The terraces and soils of increasing age are used to compare the <span class="hlt">10</span><span class="hlt">Be</span> inventory with a simple model of accumulation, decay and erosion. The data show that the distribution of <span class="hlt">10</span><span class="hlt">Be</span> varies with soil horizon clay content, that the residence time of <span class="hlt">10</span><span class="hlt">Be</span> in these horizons exceeds 105 years, and that to a rough approximation the inventory of <span class="hlt">10</span><span class="hlt">Be</span> in a thoroughly sampled soil profile fits the equation: N = (q - Em)(1 - e-????)/?? where q is delivery rate, E is erosion rate, m is the concentration of <span class="hlt">10</span><span class="hlt">Be</span> in the eroding surface layer, ?? is the decay constant, and t is the age of the depositional unit from which the soil has developed. The general applicability of this model is uncertain and warrants further testing in well-calibrated terrace sequences. ?? 1986.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25459713','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25459713"><span id="translatedtitle">Vibrations and reorientations of NH3 molecules in [Mn(NH3)6](ClO4)2 studied by infrared spectroscopy and theoretical (DFT) calculations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hetmańczyk, Joanna; Hetmańczyk, Łukasz; Migdał-Mikuli, Anna; Mikuli, Edward</p> <p>2015-02-01</p> <p>The vibrational and reorientational motions of NH3 ligands and ClO4(-) anions were investigated by Fourier transform middle-infrared spectroscopy (FT-IR) in the high- and low-temperature phases of [Mn(NH3)6](ClO4)2. The temperature dependencies of full width at half maximum (FWHM) of the infrared bands at: 591 and 3385cm(-1), associated with: ρr(NH3) and νas(N-H) modes, respectively, indicate that there exist fast (correlation times τR≈10(-12)-10(-13)s) reorientational motions of NH3 ligands, with a mean values of activation energies: 7.8 and 4.5kJmol(-1), in the phase I and II, respectively. These reorientational motions of NH3 ligands are only slightly disturbed in the phase transition region and do not significantly contribute to the phase transition mechanism. Fourier transform far-infrared and middle-infrared spectra with decreasing of temperature indicated characteristic changes at the vicinity of PT at TC(c)=137.6K (on cooling), which suggested lowering of the crystal structure symmetry. Infrared spectra of [Mn(NH3)6](ClO4)2 were recorded and interpreted by comparison with respective theoretical spectra calculated using DFT method (B3LYP functional, LANL2DZ ECP basis set (on Mn atom) and 6-311+G(d,p) basis set (on H, N, Cl, O atoms) for the isolated equilibrium two models (Model 1 - separate isolated [Mn(NH3)6](2+) cation and ClO4(-) anion and Model 2 - [Mn(NH3)6(ClO4)2] complex system). Calculated optical spectra show a good agreement with the experimental infrared spectra (FT-FIR and FT-MIR) for the both models. PMID:25459713</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18389270','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18389270"><span id="translatedtitle">Intercomparison study on (152)Eu gamma ray and (<span class="hlt">36</span>)<span class="hlt">Cl</span> AMS measurements for development of the new Hiroshima-Nagasaki Atomic Bomb Dosimetry System 2002 (DS02).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hoshi, M; Endo, S; Tanaka, K; Ishikawa, M; Straume, T; Komura, K; Rühm, W; Nolte, E; Huber, T; Nagashima, Y; Seki, R; Sasa, K; Sueki, K; Fukushima, H; Egbert, S D; Imanaka, T</p> <p>2008-07-01</p> <p>In the process of developing a new dosimetry system for atomic bomb survivors in Hiroshima and Nagasaki (DS02), an intercomparison study between (152)Eu and (<span class="hlt">36</span>)<span class="hlt">Cl</span> measurements was proposed, to reconcile the discrepancy previously observed in the Hiroshima data between measurements and calculations of thermal neutron activation products. Nine granite samples, exposed to the atomic-bomb radiation in Hiroshima within 1,200 m of the hypocenter, as well as mixed standard solutions containing known amounts of europium and chlorine that were neutron-activated by a (252)Cf source, were used for the intercomparison. Gamma-ray spectrometry for (152)Eu was carried out with ultra low-background Ge detectors at the Ogoya Underground Laboratory, Kanazawa University, while three laboratories participated in the (<span class="hlt">36</span>)<span class="hlt">Cl</span> measurement using accelerator mass spectrometry (AMS): The Technical University of Munich, Germany, the Lawrence Livermore National Laboratory, USA and the University of Tsukuba, Japan. Measured values for the mixed standard solutions showed good agreement among the participant laboratories. They also agreed well with activation calculations, using the neutron fluences monitored during the (252)Cf irradiation, and the corresponding activation cross-sections taken from the JENDL-3.3 library. The measured-to-calculated ratios obtained were 1.02 for (152)Eu and 0.91-1.02 for (<span class="hlt">36</span>)<span class="hlt">Cl</span>, respectively. Similarly, the results of the granite intercomparison indicated good agreement with the DS02 calculation for these samples. An average measured-to-calculated ratio of 0.98 was obtained for all granite intercomparison measurements. The so-called neutron discrepancy that was previously observed and that which included increasing measured-to-calculated ratios for thermal neutron activation products for increasing distances beyond 1,000 m from the hypocenter was not seen in the results of the intercomparison study. The previously claimed discrepancy could be explained by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AcSpA.136.1515H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AcSpA.136.1515H"><span id="translatedtitle">Vibrations and reorientations of NH3 molecules in [Mn(NH3)6](ClO4)2 studied by infrared spectroscopy and theoretical (DFT) calculations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hetmańczyk, Joanna; Hetmańczyk, Łukasz; Migdał-Mikuli, Anna; Mikuli, Edward</p> <p>2015-02-01</p> <p>The vibrational and reorientational motions of NH3 ligands and ClO4- anions were investigated by Fourier transform middle-infrared spectroscopy (FT-IR) in the high- and low-temperature phases of [Mn(NH3)6](ClO4)2. The temperature dependencies of full width at half maximum (FWHM) of the infrared bands at: 591 and 3385 cm-1, associated with: ρr(NH3) and νas(N-H) modes, respectively, indicate that there exist fast (correlation times τR ≈ 10-12-10-13 s) reorientational motions of NH3 ligands, with a mean values of activation energies: 7.8 and 4.5 kJ mol-1, in the phase I and II, respectively. These reorientational motions of NH3 ligands are only slightly disturbed in the phase transition region and do not significantly contribute to the phase transition mechanism. Fourier transform far-infrared and middle-infrared spectra with decreasing of temperature indicated characteristic changes at the vicinity of PT at TCc = 137.6 K (on cooling), which suggested lowering of the crystal structure symmetry. Infrared spectra of [Mn(NH3)6](ClO4)2 were recorded and interpreted by comparison with respective theoretical spectra calculated using DFT method (B3LYP functional, LANL2DZ ECP basis set (on Mn atom) and 6-311 + G(d,p) basis set (on H, N, Cl, O atoms) for the isolated equilibrium two models (Model 1 - separate isolated [Mn(NH3)6]2+ cation and ClO4- anion and Model 2 - [Mn(NH3)6(ClO4)2] complex system). Calculated optical spectra show a good agreement with the experimental infrared spectra (FT-FIR and FT-MIR) for the both models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JNuM..464..405T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JNuM..464..405T"><span id="translatedtitle">Ion irradiation of 37Cl implanted nuclear graphite: Effect of the energy deposition on the chlorine behavior and consequences for the mobility of <span class="hlt">36</span><span class="hlt">Cl</span> in irradiated graphite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Toulhoat, N.; Moncoffre, N.; Bérerd, N.; Pipon, Y.; Blondel, A.; Galy, N.; Sainsot, P.; Rouzaud, J.-N.; Deldicque, D.</p> <p>2015-09-01</p> <p>Graphite is used in many types of nuclear reactors due to its ability to slow down fast neutrons without capturing them. Whatever the reactor design, the irradiated graphite waste management has to be faced sooner or later regarding the production of long lived or dose determining radioactive species such as 14C, 3H or <span class="hlt">36</span><span class="hlt">Cl</span>. The first carbon dioxide cooled, graphite moderated nuclear reactors resulted in a huge quantity of irradiated graphite waste for which the management needs a previous assessment of the radioactive inventory and the radionuclide's location and speciation. As the detection limits of usual spectroscopic methods are generally not adequate to detect the low concentration levels (<1 ppm) of the radionuclides, we used an indirect approach based on the implantation of 37Cl, to simulate the presence of <span class="hlt">36</span><span class="hlt">Cl</span>. Our previous studies show that temperature is one of the main factors to be considered regarding the structural evolution of nuclear graphite and chlorine mobility during reactor operation. However, thermal release of chlorine cannot be solely responsible for the depletion of the <span class="hlt">36</span><span class="hlt">Cl</span> inventory. We propose in this paper to study the impact of irradiation and its synergetic effects with temperature on chlorine release. Indeed, the collision of the impinging neutrons with the graphite matrix carbon atoms induces mainly ballistic collisions. However, a small part of the recoil carbon atom energy is also transferred to the lattice through electronic excitation. This paper aims at elucidating the effects of the different irradiation regimes (ballistic and electronic) using ion irradiation, on the mobility of implanted 37Cl, taking into account the initial disorder level of the nuclear graphite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7165484','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7165484"><span id="translatedtitle">sup <span class="hlt">10</span> <span class="hlt">Be</span> study of rapid erosion in Taiwan</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chenfeng You; Juchin Chen National Taiwan Univ., Taipei ); Typhoon Lee; Jason Jiunsan Shen ); Brown, L. )</p> <p>1988-11-01</p> <p>Cosmogenic {sup <span class="hlt">10</span>}<span class="hlt">Be</span> was measured using accelerator mass spectrometry in soils and sediments to study the erosion of Taiwan, which has the highest denudation rate in the world. The river sediments in Taiwan have very low {sup <span class="hlt">10</span>}<span class="hlt">Be</span> concentrations, around 5 million atoms per gram, about 1/45 the world wide average. This is the direct consequence of its high sediment yield of ore than 1,000 mg/cm{sup 2}/yr, 70 times the world average. Combining these values the authors found that, for Taiwan as a whole, the {sup <span class="hlt">10</span>}<span class="hlt">Be</span> output to the sea only slightly exceeds the input from the rain, a situation typical of many areas around the world. Therefore, even in this example of extremely rapid erosion, {sup <span class="hlt">10</span>}<span class="hlt">Be</span> seems to remain a useful indicator for erosion status. The total {sup <span class="hlt">10</span>}<span class="hlt">Be</span> inventory found in a soil profile from a geologically stable area is at least 18% of the maximum possible inventory. The minimum age thus estimated for the soil is 0.11 Ma, in reasonable agreement with estimates from other means. The maximum erosion rate for this area thus estimated is at most 0.14 mg/cm{sup 2}/yr, four orders of magnitude slower than the average value observed for Taiwan. They also demonstrate that the shelf sediments around Taiwan have received the admixing of a {sup <span class="hlt">10</span>}<span class="hlt">be</span> rich component from the ocean and would give a poor estimate for material eroded from Taiwan.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMEP53A0736G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMEP53A0736G"><span id="translatedtitle">Production Rate of Cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> in Magnetite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Granger, D. E.; Rogers, H. E.; Riebe, C. S.; Lifton, N. A.</p> <p>2013-12-01</p> <p>Cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> is widely used for determining exposure ages, soil production rates, and catchment-wide erosion rates. To date, measurements have been almost exclusively in the mineral quartz (SiO2), which is resistant to weathering and easily cleaned of meteoric <span class="hlt">10</span><span class="hlt">Be</span> contamination. However, this limits the method to quartz-bearing rocks and requires specialized laboratories due to the need for large quantities of hydrofluoric acid (HF). Here, we present initial results for <span class="hlt">10</span><span class="hlt">Be</span> production in the mineral magnetite (Fe3O4). Magnetite offers several advantages over quartz; it is (1) present in mafic rocks, (2) easily collected in the field, (3) quickly and easily separated in the lab, and (4) digested without HF. In addition, <span class="hlt">10</span><span class="hlt">Be</span> can be measured in both detrital quartz and magnetite from the same catchment to yield information about the intensity of chemical weathering (Rogers et al., this conference). The <span class="hlt">10</span><span class="hlt">Be</span> production rate in magnetite relative to quartz was determined for a granitic boulder from Mt. Evans, Colorado, USA. The boulder was crushed and homogenized to facilitate production rate comparisons among various minerals. We separated magnetite using a combination of hand magnets, froth flotation, and a variety of selective chemical dissolutions in dithionite-citrate-bicarbonate solution, 5% nitric acid (HNO3) and 1% HF/HNO3. Six aliquots of magnetite were analyzed for <span class="hlt">10</span><span class="hlt">Be</span> and compared to quartz. Three aliquots that were not exposed to 1% HF/HNO3 were contaminated with meteoric <span class="hlt">10</span><span class="hlt">Be</span>, probably associated with residual mica. Three aliquots that were exposed to 1% HF/HNO3 treatments agreed to within 2% measurement uncertainty. Our preliminary results indicate that the relative production rate by mass of <span class="hlt">10</span><span class="hlt">Be</span> in magnetite and quartz is 0.462 × 0.012. Our results are similar to theoretically predicted values. Recently updated excitation functions for neutron and proton spallation reactions allow us to partition <span class="hlt">10</span><span class="hlt">Be</span> production in quartz and magnetite among</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMEP51B0554C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMEP51B0554C"><span id="translatedtitle">Do Fungi Transport <span class="hlt">10</span><span class="hlt">Be</span> During Wood Degradation?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Conyers, G.; Granger, D. E.</p> <p>2010-12-01</p> <p>Meteoric cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> is increasingly used to determine erosion and soil transport rates. To calculate these rates, it is assumed that <span class="hlt">10</span><span class="hlt">Be</span> is a conservative passive tracer of soil particles. However, there is experimental evidence that beryllium is mobilized in natural soils complexed with organic acids. For example, up to 50% of beryllium can be mobilized by humic acids in soils at pH 7 (Takahashi et al., 1999). Beryllium is also known to be taken up in plants such as tobacco and vegetables (World Health Organization, 1990) at ppm levels, primarily as organic acid chelates. It is not known to what extent biological beryllium transport in the environment affects the cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> budget, or how it influences beryllium mobility. In this study, we address a problem recognized early in the development of meteoric <span class="hlt">10</span><span class="hlt">Be</span> methods. It has been observed that decayed organic matter in soils and sediments contains very high concentrations of <span class="hlt">10</span><span class="hlt">Be</span> of up to 109-1010 atoms/g (Lundberg, et al., 1983). On the other hand, living trees contain much lower concentrations of 106 atoms/g (Klein et al., 1982). The driving question for this study is how <span class="hlt">10</span><span class="hlt">Be</span> becomes bound to decayed organic matter. Direct fallout seems unlikely as the residence time of organic matter in soil is too short. One possibility is that <span class="hlt">10</span><span class="hlt">Be</span> is transported by fungi. Wood-degrading fungi are known to transport and bioaccumulate metals from large areas, facilitated by acids such as oxalic acid in the fungal hyphae. To test the hypothesis that fungi transport <span class="hlt">10</span><span class="hlt">Be</span>, we analyzed both intact and fungally degraded wood of oak, hickory, and hemlock. From these data, we reached two conclusions (observations?): 1) Oak has a <span class="hlt">10</span><span class="hlt">Be</span> concentration of about 2x106 at/g, similar to that observed by Klein et al. (1982). Hickory has a significantly higher concentration of about 3x107 atoms/g, confirming observations that hickory bioaccumulates beryllium. Using these data, the inventory of <span class="hlt">10</span><span class="hlt">Be</span> in a temperate forest is expected</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.2151L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.2151L"><span id="translatedtitle">Multi-isotope comparison of 3He, 21Ne, and <span class="hlt">36</span><span class="hlt">Cl</span> moraine ages from the high-altitude central Puna Plateau, NW Argentina (24°S)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Luna, Lisa; Bookhagen, Bodo; Niedermann, Samuel; Merchel, Silke; Rugel, Georg; Scharf, Andreas; Strecker, Manfred</p> <p>2016-04-01</p> <p>Glacial deposits on the high-altitude, arid Puna Plateau of northwestern Argentina document past changes in climate, but the associated geomorphic features have never been directly dated. The plateau is situated in the "Arid Diagonal," the hyper-arid transition zone between the Westerlies precipitation dominated southern Andes, and the South American Summer Monsoon controlled central Andes. Despite the climatically critical position of the Puna Plateau, paleoclimate data for the region is extremely sparse. This study provides direct age control of glacial moraine deposits from the central Puna Plateau (24°S) at elevations of 4500-5000 m through cosmogenic surface exposure dating. The volcanic lithologies of the deposits additionally allow for comparison of production rates from multiple cosmogenic isotope systems at low latitude and high elevation. Moraine boulders were dated using cosmogenic 3He from pyroxene, 21Ne from quartz, and <span class="hlt">36</span><span class="hlt">Cl</span> from feldspars. Preliminary data suggests that the most extensive glaciation occurred more than 80 ka ago, and that an additional prominent advance occurred at ~39 ka. In addition, comparison of isotope production ratios from low latitude and high elevation will contribute to better constrained production rates, particularly for <span class="hlt">36</span><span class="hlt">Cl</span>, for which global production rate estimates are highly variable. This study documents Quaternary climate changes on the Puna Plateau, while at the same time improving production rate agreement between multiple cosmogenic isotope systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015A%26A...578A.113K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015A%26A...578A.113K&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span> kinematics: superbubbles following the spiral arms?. Constraints from the statistics of star clusters and HI supershells</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krause, Martin G. H.; Diehl, Roland; Bagetakos, Yiannis; Brinks, Elias; Burkert, Andreas; Gerhard, Ortwin; Greiner, Jochen; Kretschmer, Karsten; Siegert, Thomas</p> <p>2015-06-01</p> <p>Context. High-energy resolution spectroscopy of the 1.8 MeV radioactive decay line of <span class="hlt">26</span><span class="hlt">Al</span> with the SPI instrument onboard the INTEGRAL satellite has recently revealed that diffuse <span class="hlt">26</span><span class="hlt">Al</span> has higher velocities than other components of the interstellar medium in the Milky Way. <span class="hlt">26</span><span class="hlt">Al</span> shows Galactic rotation in the same sense as the stars and other gas tracers, but reaches excess velocities of up to 300 km s-1. Aims: We investigate whether this result can be understood in the context of superbubbles, taking into account the statistics of young star clusters and HI supershells as well as the association of young star clusters with spiral arms. Methods: We derived energy output and <span class="hlt">26</span><span class="hlt">Al</span> mass of star clusters as a function of the cluster mass by population synthesis from stellar evolutionary tracks of massive stars. Using the limiting cases of weakly and strongly dissipative superbubble expansion, we linked this to the size distribution of HI supershells and assessed the properties of possible <span class="hlt">26</span><span class="hlt">Al</span>-carrying superbubbles. Results: <span class="hlt">26</span><span class="hlt">Al</span> is produced by star clusters of all masses above ≈200 M⊙, is roughly equally contributed over a logarithmic star cluster mass scale and strongly linked to the injection of feedback energy. The observed superbubble size distribution cannot be related to the star cluster mass function in a straightforward manner. To avoid the added volume of all superbubbles exceeding the volume of the Milky Way, individual superbubbles have to merge frequently. If any two superbubbles merge, or if <span class="hlt">26</span><span class="hlt">Al</span> is injected off-centre into a larger HI supershell, we expect the hot <span class="hlt">26</span><span class="hlt">Al</span>-carrying gas to obtain velocities of the order of the typical sound speed in superbubbles, ≈300 km s-1 before decay. For star formation coordinated by the spiral arm pattern which, inside co-rotation, is overtaken by the faster moving stars and gas, outflows from spiral arm star clusters would preferentially flow into the cavities that are inflated by previous star formation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1255183-feasibility-isobaric-suppression-via-post-accelerator-foil-stripping-measurement-feasibility-isobaric-suppression-via-post-accelerator-foil-stripping-measurement','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1255183-feasibility-isobaric-suppression-via-post-accelerator-foil-stripping-measurement-feasibility-isobaric-suppression-via-post-accelerator-foil-stripping-measurement"><span id="translatedtitle">The feasibility of isobaric suppression of 26Mg via post-accelerator foil stripping for the measurement of <span class="hlt">26</span><span class="hlt">Al</span> [The feasibility of isobaric suppression of 26Mg via post-accelerator foil stripping for the measurement of <span class="hlt">26</span><span class="hlt">Al</span>.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Tumey, Scott J.; Brown, Thomas A.; Finkel, Robert C.; Rood, Dylan H.</p> <p>2012-09-13</p> <p>Most accelerator mass spectrometry measurements of <span class="hlt">26</span><span class="hlt">Al</span> utilize the Al- ion despite lower source currents compared with AlO- since the stable isobar 26Mg does not form elemental negative ions. A gas-filled magnet allows sufficient suppression of 26Mg thus enabling the use of the more intense <span class="hlt">26</span><span class="hlt">Al</span>O- ion. However, most AMS systems do not include a gas-filled magnet. We therefore explored the feasibility of suppressing 26Mg by using a post-accelerator stripping foil. With this approach, combined with the use of alternative cathode matrices, we were able to suppress 26Mg by a factor of twenty. This suppression was insufficient to enable themore » use of <span class="hlt">26</span><span class="hlt">Al</span>O-, however further refinement of our system may permit its use in the future.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/835912','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/835912"><span id="translatedtitle">Activation Measurements for Thermal Neutrons, U.S. Measurements of <span class="hlt">36</span><span class="hlt">Cl</span> in Mineral Samples from Hiroshima and Nagasaki; and Measurement of 63 Ni in Copper Samples From Hiroshima by Accelerator Mass Spectrometry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tore Straume; Alfredo A. Marchetti; Stephen D. Egbert; James A. Roberts; Ping Men; Shoichiro Fujita; Kiyoshi Shizuma; Masaharu Hoshi; G. Rugel; W. Ruhm; G. Korschinek; J. E. McAninch; K. L. Carroll; T. Faestermann; K. Knie; R. E. Martinelli; A. Wallner; C. Wallner</p> <p>2005-01-14</p> <p>The present paper presents the {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> measurement effort in the US. A large number of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> measurements have been made in both granite and concrete samples obtained from various locations and distances in Hiroshima and Nagasaki. These measurements employed accelerator mass spectrometry (AMS) to quantify the number of atoms of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> per atom of total Cl in the sample. Results from these measurements are presented here and discussed in the context of the DS02 dosimetry reevaluation effort for Hiroshima and Nagasaki atomic-bomb survivors. The production of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> by bomb neutrons in mineral samples from Hiroshima and Nagasaki was primarily via the reaction {sup 35}Cl(n,{gamma}){sup <span class="hlt">36</span>}<span class="hlt">Cl</span>. This reaction has a substantial thermal neutron cross-section (43.6 b at 0.025 eV) and the product has a long half-life (301,000 y). hence, it is well suited for neutron-activation detection in Hiroshima and Nagasaki using AMS more than 50 years after the bombings. A less important reaction for bomb neutrons, {sup 39}K(n,{alpha}){sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, typically produces less than 10% of the {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> in mineral samples such as granite and concrete, which contain {approx} 2% potassium. In 1988, only a year after the publication of the DS86 final report (Roesch 1987), it was demonstrated experimentally that {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> measured using AMS should be able to detect the thermal neutron fluences at the large distances most relevant to the A-bomb survivor dosimetry. Subsequent measurements in mineral samples from both Hiroshima and Nagasaki validated the experimental findings. The potential utility of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> as a thermal neutron detector in Hiroshima was first presented by Haberstock et al. who employed the Munich AMS facility to measure {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl ratios in a gravestone from near the hypocenter. That work subsequently resulted in an expanded {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> effort in Germany that paralleled the US work. More recently, there have also been {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> measurements made by a Japanese</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23811127','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23811127"><span id="translatedtitle">Translocation of (125)I, (75)Se and (<span class="hlt">36</span>)<span class="hlt">Cl</span> to edible parts of radish, potato and green bean following wet foliar contamination under field conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Henner, P; Hurtevent, P; Thiry, Y; Levchuk, S; Yoschenko, V; Kashparov, V</p> <p>2013-10-01</p> <p>Specific translocation factor values (ftr) for (129)I, (79)Se and (<span class="hlt">36</span>)<span class="hlt">Cl</span> following foliar transfer are still missing from the IAEA reference databases. The translocation of the short-lived isotopes, (125)I, (75)Se, and (<span class="hlt">36</span>)<span class="hlt">Cl</span>, to radish, potato and green bean edible parts was measured under field conditions following acute and chronic wet foliar contamination at various plant growth stages in the absence of leaching caused by rain. The translocation factors obtained for (125)I ranged from 0.8 to 2.6% for radish, from 0.1 to 2.3% for potato and from 0.1 to 2.6% for bean. The translocation factors obtained for (75)Se ranged from 6.3 to 21% for radish, from 1.6 to 32.6% for potato and from 7.7 to 22.8% for bean (values similar to Cs or even higher). The translocation factors obtained for (<span class="hlt">36</span>)<span class="hlt">Cl</span> were close to those for (75)Se and ranged from 4.3 to 28.8% for radish, from 0.5 to 31.5% for potato and from 4.3 to 16.3% for bean. Iodide showed the lowest apparent mobility because of its preferential fixation in or on the leaves and a significant amount was probably volatilized. Selenite internal transfer was significant and possibly followed the sulfur metabolic pathway. Chloride was very mobile and quickly diffused throughout the plant. The translocation factors varied with the growth stage and depended on the development state of the edible tissue and its associated sink strength for nutrients and assimilates. For radish, translocation was high during the early vegetative stages. For potato, wheat and bean, a major peak in translocation was seen during the flowering growth stage and the concomitant growth of potato tubers. An additive effect of successive contamination events on translocated elements was shown in radish but not in bean and potato. The highest translocation value obtained for an acute contamination event was shown to be an adequate, conservative indicator of chronic contamination in absence of specific values. Due to the absence of rain leaching during</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1814251Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1814251Y"><span id="translatedtitle">Deriving earthquake history of the Knidos Fault Zone, SW Turkey, using cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> surface exposure dating of the fault scarp.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yildirim, Cengiz; Ersen Aksoy, Murat; Akif Sarikaya, Mehmet; Tuysuz, Okan; Genc, S. Can; Ertekin Doksanalti, Mustafa; Sahin, Sefa; Benedetti, Lucilla; Tesson, Jim; Aster Team</p> <p>2016-04-01</p> <p>Formation of bedrock fault scarps in extensional provinces is a result of large and successive earthquakes that ruptured the surface several times. Extraction of seismic history of such faults is critical to understand the recurrence intervals and the magnitude of paleo-earthquakes and to better constrain the regional seismic hazard. Knidos on the Datca Peninsula (SW Turkey) is one of the largest cities of the antique times and sits on a terraced hill slope formed by en-echelon W-SW oriented normal faults. The Datça Peninsula constitutes the southern boundary of the Gulf of Gökova, one of the largest grabens developed on the southernmost part of the Western Anatolian Extensional Province. Our investigation relies on cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> surface exposure dating of limestone faults scarps. This method is a powerful tool to reconstruct the seismic history of normal faults (e.g. Schlagenhauf et al 2010, Benedetti et al. 2013). We focus on one of the most prominent fault scarp (hereinafter Mezarlık Fault) of the Knidos fault zone cutting through the antique Knidos city. We collected 128 pieces of tablet size (10x20cm) 3-cm thick samples along the fault dip and opened 4 conventional paleoseismic trenches at the base of the fault scarp. Our <span class="hlt">36</span><span class="hlt">Cl</span> concentration profile indicates that 3 to 4 seismic events ruptured the Mezarlık Fault since Last Glacial Maximum (LGM). The results from the paleoseismic trenching are also compatible with <span class="hlt">36</span><span class="hlt">Cl</span> results, indicating 3 or 4 seismic events that disturbed the colluvium deposited at the base of the scarp. Here we will present implications for the seismic history and the derived slip-rate of the Mezarlık Fault based on those results. This project is supported by The Scientific and Technological Research Council of Turkey (TUBITAK, Grant number: 113Y436) and it was conducted with the Decision of the Council of Ministers with No. 2013/5387 on the date 30.09.2013 and was done with the permission of Knidos Presidency of excavation in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004E%26PSL.225..163P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004E%26PSL.225..163P"><span id="translatedtitle">Slip history of the Magnola fault (Apennines, Central Italy) from <span class="hlt">36</span><span class="hlt">Cl</span> surface exposure dating: evidence for strong earthquakes over the Holocene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Palumbo, Luigi; Benedetti, Lucilla; Bourlès, Didier; Cinque, Aldo; Finkel, Robert</p> <p>2004-08-01</p> <p>To better understand the mechanics of deformation in the Mediterranean and the role that the convergence between Africa and Europe plays, it is necessary to know the deformation field at different time scales. Here we use in situ <span class="hlt">36</span><span class="hlt">Cl</span> surface exposure dating of exposed bedrock fault scarps to determine earthquake time-slip histories and to quantify slip rates over the last several thousand years. This information allows us to delineate the seismic history of normal faulting within the Mediterranean area over that time period. We have studied the limestone scarp produced by the Magnola fault in the Central Apennines, Italy. The Magnola fault, in the Fucino area, is an active, 15-km long, normal fault striking WNW and dipping SSW. The range front morphology, characterised by steep triangular facets separated by V-shaped valleys and wine-glass canyons, suggests that the Magnola fault has been active for at least the last several hundred thousand years. At the base of the facets, the fault cuts limestone bedrock to produce a well-preserved normal fault scarp 10 to 12 m high. The distribution of <span class="hlt">36</span><span class="hlt">Cl</span> concentration versus the height along that scarp is best explained by a minimum of five and a maximum of seven successive earthquake exhumations, with slips varying between 1.5 and 3 m. An age of ˜5 ka at the base of the scarp and of ˜12 ka at the top yields a slip rate of ˜0.8 mm/year. The absence of any event on this fault during the last 5000 years suggests either that a future event is imminent on the Magnola fault or that the fault has entered a quiescent period with much longer recurrence time. Our study confirms that the Magnola fault scarp is post-glacial and supports the hypothesis that similar scarps in the Mediterranean are also post-glacial.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007NuPhA.787..451B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007NuPhA.787..451B"><span id="translatedtitle">New assignments for <span class="hlt">10</span><span class="hlt">Be</span> states from the 12C( 12C, 14O) <span class="hlt">10</span><span class="hlt">Be</span> reaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bohlen, H. G.; Dorsch, T.; Kokalova, Tz.; von Oertzen, W.; Schulz, Ch.; Wheldon, C.</p> <p>2007-05-01</p> <p>The two-proton pick-up reaction 12C( 12C, 14O) <span class="hlt">10</span><span class="hlt">Be</span> has been measured at 211.4 MeV incident energy to study the structure of <span class="hlt">10</span><span class="hlt">Be</span> states. This reaction populates most strongly 0 + and 2 + two-proton hole-configurations in the Ip-shell, but also odd-parity states. A two-step mechanism is needed in the latter case with particle-hole excitations of the type (lp) -1(2sld) 1 in inelastic excitation (including neutron excitations) in the one step, and the pick-up of a pair of protons from 12C in the other step. For all observed states the oscillatory structure of the angular distributions is characteristic of their spins, as can be verified for states with known spins. In this way we can make the firm spin assignments of 4 + and 3 - for the states at 11.8 MeV and 10.55 MeV, respectively. From the reaction mechanism, which offers optimum conditions to populate the 4 + configuration in the Ip-shell, and from the J(J+l)-rule for excitation energies within a rotational band we conclude, that the assigned 4 + state is most probably a member of the ground state band of <span class="hlt">10</span><span class="hlt">Be</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013SSRv..176..333M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013SSRv..176..333M"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> Production in the Atmosphere by Galactic Cosmic Rays</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matthiä, Daniel; Herbst, Klaudia; Heber, Bernd; Berger, Thomas; Reitz, Günther</p> <p>2013-06-01</p> <p>Galactic cosmic ray nuclei and energetic protons produced in solar flares and accelerated by coronal mass ejections are the main sources of high-energy particles of extraterrestrial origin in near-Earth space and inside the Earth's atmosphere. The intensity of galactic cosmic rays inside the heliosphere is strongly influenced by the modulation of the interstellar source particles on their way through interplanetary space. Among others, this modulation depends on the activity of the Sun, and the resulting intensity of the energetic particles in the atmosphere is an indicator of the solar activity. Therefore, rare isotopes found in historical archives and produced by spallation reactions of primary and secondary hadrons of cosmic origin in the atmosphere, so-called cosmogenic nuclides, can be used to reconstruct the solar activity in the past. The production rate of <span class="hlt">10</span><span class="hlt">Be</span>, one of the cosmogenic nuclides most adequate to study the solar activity, is presented showing its variations with geographic latitude and altitude and the dependence on different production cross-sections present in literature. In addition, estimates for altitude integrated production rates of <span class="hlt">10</span><span class="hlt">Be</span> at different locations since the early nineteen sixties are shown.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015A%26A...575A..77K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015A%26A...575A..77K"><span id="translatedtitle">The lost sunspot cycle: New support from <span class="hlt">10</span><span class="hlt">Be</span> measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Karoff, C.; Inceoglu, F.; Knudsen, M. F.; Olsen, J.; Fogtmann-Schulz, A.</p> <p>2015-03-01</p> <p>It has been suggested that the shortage in the number of spots on the surface of the Sun between 1790 and 1830, known as the Dalton minimum, contained an extra cycle that was not identified in the original sunspot record by Wolf. Though this cycle was shorter and weaker than the average solar cycle, it shifted the magnetic parity of the solar magnetic field of the earlier cycles. This extra cycle is sometimes referred to as the "lost solar cycle" or "cycle 4b". Here we reanalyse <span class="hlt">10</span><span class="hlt">Be</span> measurements with annual resolution from the North Greenland Ice Core Project in order to investigate if the hypothesis regarding a lost sunspot cycle is supported by these measurements. Specifically, we make use of the fact that the Galactic cosmic rays, responsible for forming <span class="hlt">10</span><span class="hlt">Be</span> in the Earth's atmosphere, are affected differently by the open solar magnetic field during even and odd solar cycles. This enables us to evaluate if the numbering of cycles earlier than cycle 5 is correct. For the evaluation, we use Bayesian analysis, which reveals that the lost sunspot cycle hypothesis is likely to be correct. We also discuss whether this cycle 4b is a real cycle or a phase catastrophe, and what implications this has for our understanding of stellar activity cycles in general.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMEP31D..06B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMEP31D..06B"><span id="translatedtitle">Reconstructing Former Sea Cliff Chronologies using Cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> Concentrations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barlow, J.; Rosser, N. J.; Petley, D. N.; Densmore, A.; Lim, M.</p> <p>2010-12-01</p> <p>The long-term evolution of coastal cliffs is poorly constrained, with implications for future coastal planning, for estimates of coastal sediment generation and for models of coastal landform evolution. While general consensus has been reached on principles governing the evolution of sea cliffs and shore platforms, process rates and the relative importance of bedrock material properties and environmental boundary conditions have not been established in any quantitative way. This is primarily the result of a lack of calibration data due to the destruction of previous cliff positions through erosive processes. A recurrent problem is that rates of erosion and retreat are often comparable to measurement uncertainties over short time scales and across representative spatial extents. Therefore, long-term rates of retreat for rock coasts remain unknown and the magnitude and pattern of coastal change during the Holocene remains at best anecdotal. With this research we address these issues by reconstructing former cliff chronologies at Staithes, UK using cosmogenic radionuclide (CRN) concentrations measured across the shore platform. While individual samples provide little certainty as to their true exposure age due to variability in topographic shielding through time, the differences in CRN concentrations taken in transect normal to the cliff are indicative of the recession rate. This relationship forms the basis of our reconstruction. Studying erosion using the concentration of cosmogenically-derived <span class="hlt">10</span><span class="hlt">Be</span> within quartz has a proven track record. This type of analysis involves the use of accelerator mass spectrometry (AMS) to quantify the concentration of cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> that has accumulated in the upper portion of the Earth’s surface. Our model of CRN accumulation assumes: negligible down-wearing of the shore platform following cliff recession, supported by studies that have directly measured erosion rates, and evidenced in the present foreshore morphology at the study</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26PSL.450..173V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26PSL.450..173V"><span id="translatedtitle">Reconciling tectonic shortening, sedimentation and spatial patterns of erosion from <span class="hlt">10</span><span class="hlt">Be</span> paleo-erosion rates in the Argentine Precordillera</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Val, Pedro; Hoke, Gregory D.; Fosdick, Julie C.; Wittmann, Hella</p> <p>2016-09-01</p> <p>The temporal evolution of erosion over million-year timescales is key to understand the development of mountain ranges and adjacent fold-and-thrust belts. While models of orogenic wedge dynamics predict an instantaneous response of erosion to pulses of rock uplift, stream-power based models predict that catchment-wide erosion maxima significantly lag behind a pulse of rock uplift. Here, we explore the relationships between rock uplift, erosion, and sediment deposition in the Argentine Precordillera fold-and-thrust belt at 30°S. Using a combination of <span class="hlt">10</span><span class="hlt">Be</span>-derived paleo-erosion rates, constraints on re-exposure using <span class="hlt">26</span><span class="hlt">Al</span>/<span class="hlt">10</span><span class="hlt">Be</span> ratios, geomorphic observations and detrital zircon provenance, we demonstrate that the attainment of maximum upland erosion rates lags the maximum rate of deformation over million-year timescales. The magnitudes and causes of the erosional delays shed new light on the catchment erosional response to tectonic deformation and rock uplift in orogenic wedges.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012LPI....43.2255K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012LPI....43.2255K"><span id="translatedtitle">Heterogeneous Distribution of ^2^6Al at the Birth of the Solar System: Evidence from Corundum-Bearing Refractory Inclusions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krot, A. N.; Makide, K.; Nagashima, K.; Huss, G. R.; Hellebrand, E.; Petaev, M. I.</p> <p>2012-03-01</p> <p>Corundum-bearing CAIs recorded heterogeneous distribution of ^2^6Al at the birth of the solar system. We suggest that ^2^6Al was injected into the protosolar molecular cloud core by a wind from a massive star and was later homogenized through the disk.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1814159T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1814159T"><span id="translatedtitle">Toward determining the uncertainties associated with the seismic histories retrieved from in situ <span class="hlt">36</span><span class="hlt">Cl</span> cosmogenic nuclide fault scarp dating: model reappraisal.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tesson, Jim; Benedetti, Lucilla</p> <p>2016-04-01</p> <p>How the past seismic activity of faults has varied over the last 20 ky is a crucial information for seismic hazard assessment and for the understanding of fault-interaction processes. Chlorine 36 in situ produced cosmogenic nuclide is increasingly used to retrieve past earthquakes histories on seismically exhumed limestone normal fault-scarps. Schlagenhauf et al. in 2010 developed a modeling code with a forward approach enabling the test of scenarii generated with a priori constraints (number of events, age and slip of events and pre-exposure time). The main shortcomings of this forward approach were the limited number of testable scenarii and the difficulty to derive the associated uncertainties. We present here a reappraisal methodology with an inverse approach using an optimization algorithm. This modelling approach enables 1-exploring the parameter space (age and slip of events), 2-finding the best scenario without a priori constraints and 3-precisely quantifying the associated uncertainties by determining the range of plausible models. Through a series of synthetic tests, we observed that the algorithm revealed a great capacity to constrain event slips and ages in a short computational time (several hours) with an accuracy that can reach 0.1 ky and 0.5 m for the age and slip of exhumation event, respectively. We also explore the influence of the pre-exposure history (amount of <span class="hlt">36</span><span class="hlt">Cl</span> accumulated when the sampled fault-plane was still buried under the colluvial wedge) and show that it has an important impact on the generated scenarii. This new modeling also allows now to accurately determining this parameter. Finally, the results show that any given [<span class="hlt">36</span><span class="hlt">Cl</span>] profile results in a unique exhumation solution. We then apply this new model to the Magnola fault (Italy) dataset (Schlgenhauf et al. 2011). In agreement the previously published results, our model also results in 3 intense periods of seismic activity. However, the contribution of the pre-exposure history is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.T43D..05S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.T43D..05S"><span id="translatedtitle">Three time scales of earthquake clustering inferred from in-situ <span class="hlt">36</span><span class="hlt">Cl</span> cosmogenic dating on the Velino-Magnola fault (Central Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schlagenhauf, A.; Manighetti, I.; Benedetti, L.; Gaudemer, Y.; Malavieille, J.; Finkel, R. C.; Pou, K.</p> <p>2010-12-01</p> <p>Using in-situ <span class="hlt">36</span><span class="hlt">Cl</span> cosmogenic exposure dating, we determine the earthquake slip release pattern over the last ~ 14 kyrs along one of the major active normal fault systems in Central Italy. The ~ 40 km-long Velino-Magnola fault (VMF) is located ~ 20 km SW from the epicenter of the devastating April 2009 l’Aquila earthquake. We sampled the VMF at five well-separated sites along its length, and modeled the <span class="hlt">36</span><span class="hlt">Cl</span> concentrations measured in the 400 samples (Schlagenhauf et al. 2010). We find that the fault has broken in large earthquakes which clustered at three different time scales -monthly, centennial and millennial. More precisely, the fault sustained phases of intense seismic activity, separated by ~ 3 kyr-long periods of relative quiescence. The phases of strong activity lasted 3-4 kyrs (millennial scale) and included 3-4 ‘rupture events’ that repeated every 0.5-1 kyr (centennial scale). Each of these ‘rupture events’ was likely a sequence of a few large earthquakes cascading in a very short time, a few months at most (monthly scale), to eventually break the entire VMF. Each earthquake apparently broke a section of the fault of 10-20 km and produced maximum surface displacements of 2-3.5 meters. The fault seems to enter a phase of intense activity when the accumulated strain reaches a specific threshold. Based on this observation, the Velino-Magnola fault seems presently in a stage of relative quiescence. Yet, it may soon re-enter a phase of paroxysmal seismic activity. If its forthcoming earthquakes are similar to those we have documented, several may occur in cascade over a short time, each with a magnitude up to 6.5-6.9. Seismic hazard is thus high in the Lazio-Abruzzo region, especially in the Fucino area. References: Schlagenhauf A., Y. Gaudemer, L. Benedetti, I. Manighetti, L. Palumbo, I. Schimmelpfennig, R. Finkel, and K. Pou (2010). Using in-situ Chlorine-36 cosmonuclide to recover past earthquake histories on limestone normal fault scarps: A</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1815392T&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1815392T&link_type=ABSTRACT"><span id="translatedtitle">Slip rate variability over the Holocene period in the middle Aterno fault system (Italy), retrieved from in situ <span class="hlt">36</span><span class="hlt">Cl</span> cosmogenic nuclide dating of exhumed fault-plane.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tesson, Jim; Benedetti, Lucilla; Pucci, Stefano; Villani, Fabio; Bourles, Didier; Keddadouche, Karim; Aumaitre, Georges</p> <p>2016-04-01</p> <p>Numerous numerical modeling studies have described and quantified non-stochastic spatio-temporal variations of earthquake occurrences within fault-networks, such as temporal clustered earthquakes or fault synchronization. However, very few long-enough paleoseismological and geological records are available to test those models against well-constrained dataset and thus account for such variability in the fault behavior. The prerequisites for improving our understanding of fault-rupture processes and thus our capacity to better assess seismic hazard are to acquire paleoseismological records that enable to derive both long-term slip-rate and short-term variability, on a large population of faults and/or within a fault system. These conditions met in Central Apennines, an extensional province where substantial paleoseismological dataset accurately described the Holocene seismic history of a dense network of normal faults. In this study we use <span class="hlt">36</span><span class="hlt">Cl</span> in situ cosmogenic nuclide to retrieve the seismic history of 3 faults belonging to the Middle Aterno fault system, from north to south: the Bazzano fault, the Roccapreturo fault and the Sulmona fault, a portion of which ruptured during the 2009 L'Aquila earthquake in Italy. We use a new modeling approach to determine the age and slip of past seismic events from the <span class="hlt">36</span><span class="hlt">Cl</span> concentration profiles. This model is based on an inverse approach and uses an optimization algorithm enabling all the parameter space (number of events, age and slip of events, pre-exposure) to be explored without a priori constraints (see Tesson et al. in session TS4.2/NH4.16/SM3.8). Using this new approach, we precisely determine the slip events occurrences over the Holocene period of those three faults. The results indicate that the three studied faults have ruptured between 4.5 and 5.5 ka, while the southernmost part of the system has also ruptured between at 1.5-3 ka (Sulmona fault and southern segment of Roccapreturo). Those results are in agreement</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21199603','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21199603"><span id="translatedtitle">Lowest l=0 proton resonance in {sup 26}Si and implications for nucleosynthesis of {sup <span class="hlt">26</span>}<span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Peplowski, P. N.; Baby, L. T.; Wiedenhoever, I.; Diffenderfer, E.; Hoeflich, P.; Rojas, A.; Volya, A.; Dekat, S. E.; Gay, D. L.; Grubor-Urosevic, O.; Kaye, R. A.; Keeley, N.</p> <p>2009-03-15</p> <p>Using a beam of the radioactive isotope {sup 25}Al, produced with the new RESOLUT facility, we measured the direct (d,n) proton-transfer reaction leading to low-lying proton resonances in {sup 26}Si. We observed the lowest l=0 proton resonance, identified with the 3{sup +} state at 5.914-MeV excitation energy. This result eliminates the largest uncertainty in astrophysical reaction rates involved in the nucleosynthesis of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26274415','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26274415"><span id="translatedtitle">Measurement of 23Na(α,p)26Mg at Energies Relevant to <span class="hlt">26</span><span class="hlt">Al</span> Production in Massive Stars.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tomlinson, J R; Fallis, J; Laird, A M; Fox, S P; Akers, C; Alcorta, M; Bentley, M A; Christian, G; Davids, B; Davinson, T; Fulton, B R; Galinski, N; Rojas, A; Ruiz, C; de Séréville, N; Shen, M; Shotter, A C</p> <p>2015-07-31</p> <p><span class="hlt">26</span><span class="hlt">Al</span> is an important radioisotope in astrophysics that provides evidence of ongoing nucleosynthesis in the Galaxy. The 23Na(α, p)26Mg reaction has been identified by a sensitivity study as being one of the most important reactions for the production of <span class="hlt">26</span><span class="hlt">Al</span> in the convective C/Ne burning shell of massive stars. Owing to large uncertainties in previous experimental data, model calculations are used for the reaction rate of 23Na(α, p)26Mg in this sensitivity study. Current experimental data suggest a reaction rate a factor of ∼40 higher than model calculations. However, a new measurement of this reaction cross section has been made in inverse kinematics in the energy range E(c.m.)=1.28-3.15  MeV at TRIUMF, and found to be in reasonable agreement with the model calculation. A new reaction rate is calculated and tight constraints on the uncertainty in the production of <span class="hlt">26</span><span class="hlt">Al</span>, due to this reaction, are determined. PMID:26274415</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26274415','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26274415"><span id="translatedtitle">Measurement of 23Na(α,p)26Mg at Energies Relevant to <span class="hlt">26</span><span class="hlt">Al</span> Production in Massive Stars.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tomlinson, J R; Fallis, J; Laird, A M; Fox, S P; Akers, C; Alcorta, M; Bentley, M A; Christian, G; Davids, B; Davinson, T; Fulton, B R; Galinski, N; Rojas, A; Ruiz, C; de Séréville, N; Shen, M; Shotter, A C</p> <p>2015-07-31</p> <p><span class="hlt">26</span><span class="hlt">Al</span> is an important radioisotope in astrophysics that provides evidence of ongoing nucleosynthesis in the Galaxy. The 23Na(α, p)26Mg reaction has been identified by a sensitivity study as being one of the most important reactions for the production of <span class="hlt">26</span><span class="hlt">Al</span> in the convective C/Ne burning shell of massive stars. Owing to large uncertainties in previous experimental data, model calculations are used for the reaction rate of 23Na(α, p)26Mg in this sensitivity study. Current experimental data suggest a reaction rate a factor of ∼40 higher than model calculations. However, a new measurement of this reaction cross section has been made in inverse kinematics in the energy range E(c.m.)=1.28-3.15  MeV at TRIUMF, and found to be in reasonable agreement with the model calculation. A new reaction rate is calculated and tight constraints on the uncertainty in the production of <span class="hlt">26</span><span class="hlt">Al</span>, due to this reaction, are determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21448880','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21448880"><span id="translatedtitle">{sup 60}Fe AND {sup <span class="hlt">26</span>}<span class="hlt">Al</span> IN CHONDRULES FROM UNEQUILIBRATED CHONDRITES: IMPLICATIONS FOR EARLY SOLAR SYSTEM PROCESSES</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mishra, R. K.; Goswami, J. N.; Rudraswami, N. G.; Tachibana, S.; Huss, G. R.</p> <p>2010-05-10</p> <p>The presence of about a dozen short-lived nuclides in the early solar system, including {sup 60}Fe and {sup <span class="hlt">26</span>}<span class="hlt">Al</span>, has been established from isotopic studies of meteorite samples. An accurate estimation of solar system initial abundance of {sup 60}Fe, a distinct product of stellar nucleosynthesis, is important to infer the stellar source of this nuclide. Previous studies in this regard suffered from the lack of exact knowledge of the time of formation of the analyzed meteorite samples. We present here results obtained from the first combined study of {sup 60}Fe and {sup <span class="hlt">26</span>}<span class="hlt">Al</span> records in early solar system objects to remove this ambiguity. Chondrules from unequilibrated ordinary chondrites belonging to low petrologic grades were analyzed for their Fe-Ni and Al-Mg isotope systematics. The Al-Mg isotope data provide the time of formation of the analyzed chondrules relative to the first solar system solids, the Ca-Al-rich inclusions. The inferred initial {sup 60}Fe/{sup 56}Fe values of four chondrules, combined with their time of formation based on Al-Mg isotope data, yielded a weighted mean value of (6.3 {+-} 2) x 10{sup -7} for solar system initial {sup 60}Fe/{sup 56}Fe. This argues for a high-mass supernova as the source of {sup 60}Fe along with {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and several other short-lived nuclides present in the early solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21450975','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21450975"><span id="translatedtitle">LITHIUM-BERYLLIUM-BORON ISOTOPIC COMPOSITIONS IN METEORITIC HIBONITE: IMPLICATIONS FOR ORIGIN OF {sup <span class="hlt">10</span>}<span class="hlt">Be</span> AND EARLY SOLAR SYSTEM IRRADIATION</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Liu, Ming-Chang; Nittler, Larry R.; Alexander, Conel M. O'D.; Lee, Typhoon</p> <p>2010-08-10</p> <p>NanoSIMS isotopic measurements of Li, Be, and B in individual hibonite grains extracted from the Murchison meteorite revealed that {sup 10}B excesses correlate with the {sup 9}Be/{sup 11}B ratios in {sup <span class="hlt">26</span>}<span class="hlt">Al</span>-free PLAty hibonite Crystals. From these data, an initial {sup <span class="hlt">10</span>}<span class="hlt">Be</span>/{sup 9}Be = (5.5 {+-} 1.6) x 10{sup -4} (2{sigma}) and {sup 10}B/{sup 11}B = 0.2508 {+-} 0.0015 can be inferred. On the other hand, chondritic boron isotopic compositions were found in {sup <span class="hlt">26</span>}<span class="hlt">Al</span>-bearing Spinel-HIBonite spherules, most likely due to contamination with normal boron. No {sup 7}Li excesses due to {sup 7}Be decay were observed. When combined with previously reported data, the new data yield the best defined {sup <span class="hlt">10</span>}<span class="hlt">Be</span>/{sup 9}Be = (5.3 {+-} 1.0) x 10{sup -4} (2{sigma}) and {sup 10}B/{sup 11}B = 0.2513 {+-} 0.0012 for PLACs. A comparison of this value and the best constrained {sup <span class="hlt">10</span>}<span class="hlt">Be</span>/{sup 9}Be = (8.8 {+-} 0.6) x 10{sup -4} in CV Ca-Al-rich inclusions supports a heterogeneous distribution of {sup <span class="hlt">10</span>}<span class="hlt">Be</span> and its protosolar irradiation origin. We consider two possible irradiation scenarios that could potentially lead to the observed Li-Be-B isotopic compositions in PLACs. Although in situ irradiation of solids with hibonite chemistry seems to provide the simplest explanation, more high quality data will be needed for quantitatively constraining the irradiation history.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23671077','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23671077"><span id="translatedtitle">182Hf-182W age dating of a <span class="hlt">26</span><span class="hlt">Al</span>-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Holst, Jesper C; Olsen, Mia B; Paton, Chad; Nagashima, Kazuhide; Schiller, Martin; Wielandt, Daniel; Larsen, Kirsten K; Connelly, James N; Jørgensen, Jes K; Krot, Alexander N; Nordlund, Ake; Bizzarro, Martin</p> <p>2013-05-28</p> <p>Refractory inclusions [calcium-aluminum-rich inclusions, (CAIs)] represent the oldest Solar System solids and provide information regarding the formation of the Sun and its protoplanetary disk. CAIs contain evidence of now extinct short-lived radioisotopes (e.g., (<span class="hlt">26</span>)<span class="hlt">Al</span>, (41)Ca, and (182)Hf) synthesized in one or multiple stars and added to the protosolar molecular cloud before or during its collapse. Understanding how and when short-lived radioisotopes were added to the Solar System is necessary to assess their validity as chronometers and constrain the birthplace of the Sun. Whereas most CAIs formed with the canonical abundance of (<span class="hlt">26</span>)<span class="hlt">Al</span> corresponding to (<span class="hlt">26</span>)<span class="hlt">Al</span>/(27)Al of ∼5 × 10(-5), rare CAIs with fractionation and unidentified nuclear isotope effects (FUN CAIs) record nucleosynthetic isotopic heterogeneity and (<span class="hlt">26</span>)<span class="hlt">Al</span>/(27)Al of <5 × 10(-6), possibly reflecting their formation before canonical CAIs. Thus, FUN CAIs may provide a unique window into the earliest Solar System, including the origin of short-lived radioisotopes. However, their chronology is unknown. Using the (182)Hf-(182)W chronometer, we show that a FUN CAI recording a condensation origin from a solar gas formed coevally with canonical CAIs, but with (<span class="hlt">26</span>)<span class="hlt">Al</span>/(27)Al of ∼3 × 10(-6). The decoupling between (182)Hf and (<span class="hlt">26</span>)<span class="hlt">Al</span> requires distinct stellar origins: steady-state galactic stellar nucleosynthesis for (182)Hf and late-stage contamination of the protosolar molecular cloud by a massive star(s) for (<span class="hlt">26</span>)<span class="hlt">Al</span>. Admixing of stellar-derived (<span class="hlt">26</span>)<span class="hlt">Al</span> to the protoplanetary disk occurred during the epoch of CAI formation and, therefore, the (<span class="hlt">26</span>)<span class="hlt">Al</span>-(26)Mg systematics of CAIs cannot be used to define their formation interval. In contrast, our results support (182)Hf homogeneity and chronological significance of the (182)Hf-(182)W clock. PMID:23671077</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23671077','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23671077"><span id="translatedtitle">182Hf-182W age dating of a <span class="hlt">26</span><span class="hlt">Al</span>-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Holst, Jesper C; Olsen, Mia B; Paton, Chad; Nagashima, Kazuhide; Schiller, Martin; Wielandt, Daniel; Larsen, Kirsten K; Connelly, James N; Jørgensen, Jes K; Krot, Alexander N; Nordlund, Ake; Bizzarro, Martin</p> <p>2013-05-28</p> <p>Refractory inclusions [calcium-aluminum-rich inclusions, (CAIs)] represent the oldest Solar System solids and provide information regarding the formation of the Sun and its protoplanetary disk. CAIs contain evidence of now extinct short-lived radioisotopes (e.g., (<span class="hlt">26</span>)<span class="hlt">Al</span>, (41)Ca, and (182)Hf) synthesized in one or multiple stars and added to the protosolar molecular cloud before or during its collapse. Understanding how and when short-lived radioisotopes were added to the Solar System is necessary to assess their validity as chronometers and constrain the birthplace of the Sun. Whereas most CAIs formed with the canonical abundance of (<span class="hlt">26</span>)<span class="hlt">Al</span> corresponding to (<span class="hlt">26</span>)<span class="hlt">Al</span>/(27)Al of ∼5 × 10(-5), rare CAIs with fractionation and unidentified nuclear isotope effects (FUN CAIs) record nucleosynthetic isotopic heterogeneity and (<span class="hlt">26</span>)<span class="hlt">Al</span>/(27)Al of <5 × 10(-6), possibly reflecting their formation before canonical CAIs. Thus, FUN CAIs may provide a unique window into the earliest Solar System, including the origin of short-lived radioisotopes. However, their chronology is unknown. Using the (182)Hf-(182)W chronometer, we show that a FUN CAI recording a condensation origin from a solar gas formed coevally with canonical CAIs, but with (<span class="hlt">26</span>)<span class="hlt">Al</span>/(27)Al of ∼3 × 10(-6). The decoupling between (182)Hf and (<span class="hlt">26</span>)<span class="hlt">Al</span> requires distinct stellar origins: steady-state galactic stellar nucleosynthesis for (182)Hf and late-stage contamination of the protosolar molecular cloud by a massive star(s) for (<span class="hlt">26</span>)<span class="hlt">Al</span>. Admixing of stellar-derived (<span class="hlt">26</span>)<span class="hlt">Al</span> to the protoplanetary disk occurred during the epoch of CAI formation and, therefore, the (<span class="hlt">26</span>)<span class="hlt">Al</span>-(26)Mg systematics of CAIs cannot be used to define their formation interval. In contrast, our results support (182)Hf homogeneity and chronological significance of the (182)Hf-(182)W clock.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.6633R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.6633R"><span id="translatedtitle">Multiple dating approach (14C, U/Th and <span class="hlt">36</span><span class="hlt">Cl</span>) of tsunami-transported reef-top megaclasts on Bonaire (Leeward Antilles) - potential and current limitations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rixhon, Gilles; May, Simon Matthias; Engel, Max; Mechernich, Silke; Keulertz, Rebecca; Schroeder-Ritzrau, Andrea; Fohlmeister, Jens; Frank, Norbert; Dunai, Tibor; Brueckner, Helmut</p> <p>2016-04-01</p> <p>Coastal hazard assessment depends on reliable information on the magnitude and frequency of past high-energy wave events (EWE: tsunamis, storms). For this purpose onshore sedimentary records represent promising geo-archives for the mid- and late-Holocene EWE history. In comparison to fine-grained sediments which have been extensively studied in the recent past, supralittoral megaclasts are less investigated, essentially due to the difficulties related to the dating of corresponding depositional events, and thus their limited value for inferring the timing of major events. On Bonaire (Leeward Antilles, Caribbean), supratidal coarse-clast deposits form prominent landforms all around the island. Fields of large boulders (up to 150 t) are among the best-studied reef-top megaclasts worldwide. Transport by Holocene tsunamis is assumed at least for the largest boulders (Engel and May, 2012). Although a large dataset of 14C and electron spin resonance (ESR) ages is available for major coral rubble ridges and ramparts, showing some age clusters during the Late Holocene, it is still debated whether these data reflect the timing of major depositional/transport event(s), and how these data sets are biased by reworking of coral fragments. In addition, different processes may be responsible for the deposition of the coral rubble ridges and ramparts (storm) and the solitary megaclasts (tsunami). As an attempt to overcome the current challenges for dating the dislocation of the megaclasts, three distinct dating methods were implemented: (i) 14C dating of boring bivalves (Lithophaga) attached to the boulders; (ii) uranium-series (U/Th) dating of post-depositional, secondary calcitic flowstone at the underside of the boulders; and (iii) surface exposure dating of overturned boulders via <span class="hlt">36</span><span class="hlt">Cl</span> concentration measurements in corals. The three 14C datings yield age estimates >37 ka, i.e. most probably beyond the applicability of the method, which sheds doubt on the usefulness of this</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016QSRv..150..130S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016QSRv..150..130S"><span id="translatedtitle">Implications of <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages from Skye, northwest Scotland for the timing of ice stream deglaciation and deglacial ice dynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Small, David; Rinterknecht, Vincent; Austin, William E. N.; Bates, Richard; Benn, Douglas I.; Scourse, James D.; Bourlès, Didier L.; Hibbert, Fiona D.</p> <p>2016-10-01</p> <p>Geochronological constraints on the deglaciation of former marine based ice streams provide information on the rates and modes by which marine based ice sheets have responded to external forcing factors such as climate change. This paper presents new <span class="hlt">36</span><span class="hlt">Cl</span> cosmic ray exposure dating from boulders located on two moraines (Glen Brittle and Loch Scavaig) in southern Skye, northwest Scotland. Ages from the Glen Brittle moraines constrain deglaciation of a major marine terminating ice stream, the Barra-Donegal Ice Stream that drained the former British-Irish Ice Sheet, depending on choice of production method and scaling model this occurred 19.9 ± 1.5-17.6 ± 1.3 ka ago. We compare this timing of deglaciation to existing geochronological data and changes in a variety of potential forcing factors constrained through proxy records and numerical models to determine what deglaciation age is most consistent with existing evidence. Another small section of moraine, the Scavaig moraine, is traced offshore through multibeam swath-bathymetry and interpreted as delimiting a later stillstand/readvance stage following ice stream deglaciation. Additional cosmic ray exposure dating from the onshore portion of this moraine indicate that it was deposited 16.3 ± 1.3-15.2 ± 0.9 ka ago. When calculated using the most up-to-date scaling scheme this time of deposition is, within uncertainty, the same as the timing of a widely identified readvance, the Wester Ross Readvance, observed elsewhere in northwest Scotland. This extends the area over which this readvance has potentially occurred, reinforcing the view that it was climatically forced.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.T51C..06D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.T51C..06D"><span id="translatedtitle">First Constraints On the Slip Rate of the Yammouneh Fault (Levant Fault System) Determined by Cosmogenic \\textsuperscript{<span class="hlt">36</span>}<span class="hlt">Cl</span> Exposure Dating of Offset Alluvial Fans</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Daëron, M.; Benedetti, L.; Tapponnier, P.; Sursock, A.; Finkel, R.</p> <p>2003-12-01</p> <p>The most active seismogenic structure along the eastern shore of the Mediterranean is the left-lateral strike-slip Levant fault, plate boundary between Arabia and Africa. To this day there is consensus neither on its present slip rate and segmentation, nor on the exact size and frequence of the earthquakes it generates. Between latitudes 33\\textsuperscript{o} N and 35\\textsuperscript{o} N in Lebanon, the Levant fault's trace veers eastwards by 24\\textsuperscript{o}, forming a 160km-long restraining bend, responsible for the uplift of Mount Lebanon (3083m). Most of the resulting transpressive deformation is partitioned between two main structures: the offshore Tripoli-Beirut thrust and the Yammouneh strike-slip fault, whose degree of seismogenic activity has been questioned (various estimations of its modern slip rate range from 0 to 8mm/yr). Using aerial photographs, satellite images, topographic maps and field observations, we mapped and measured left-laterally offset alluvial fans and gullies along the Yammouneh fault. The measured offsets range from less than 10m to about 3km. To constrain the slip rate of the Yammouneh fault, limestone cobbles were sampled on three alluvial fans, each offset by 40--50m. The concentrations of \\textsuperscript{<span class="hlt">36</span>}<span class="hlt">Cl</span>\\ and stable Chlorine in the 48 samples were measured by accelerator mass spectrometry at the LLNL-CAMS. The first results suggest an average slip rate of 5--10mm/yr along the Yammouneh fault in the last 8,000 years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21596675','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21596675"><span id="translatedtitle">Precise measurement of the half-life of the Fermi {beta} decay of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup m}</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Scott, Rebecca J.; Thompson, Maxwell N.; Rassool, Roger P.; O'Keefe, Graeme J.</p> <p>2011-08-15</p> <p>State-of-the-art signal digitization and analysis techniques have been used to measure the half-life of the Fermi {beta} decay of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup m}. The half-life was determined to be 6347.8 {+-} 2.5 ms. This new datum contributes to the experimental testing of the conserved-vector-current hypothesis and the required unitarity of the Cabibbo-Kobayashi-Maskawa matrix: two essential components of the standard model. Detailed discussion of the experimental techniques and data analysis and a thorough investigation of the statistical and systematic uncertainties are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992Metic..27Q.241K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992Metic..27Q.241K"><span id="translatedtitle">The Prediction of the Saturated Activity of <span class="hlt">26</span><span class="hlt">Al</span> in Non-Antarctic Stony Meteorites from their Chemical Compositions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Keith, J. E.; Heydegger, H. R.</p> <p>1992-07-01</p> <p>We have assembled from the literature a database of over 300 non-Antarctic stony meteorites, containing information about their chemical composition, date of fall, total mass, and gas exposure age, etc. We have developed an iterative algorithm using weighted linear multivariate regression, which surveys all the independent variables in the database, recommends the best 26 models (combinations of variables) for the prediction of Al activity, and using those models, performs weighted linear multivariate regressions. By requiring that the residuals be normally distributed, under- and super-saturated meteorites are discovered and eliminated. This process is iterated until a stable solution is obtained. As a result, we obtained a set of 128 saturated, 50 unsaturated, and 10 supersaturated meteorites. We find that the expression: ^<span class="hlt">26</span><span class="hlt">Al</span> = (5.28+-0.81) . Al + (2.59+- 0.06) . Si + (1.57+-0.39) . S + (1.52+-0.59) . Ca, Chi^2(sub)nu = 2.59, where the elemental concentration is given in weight 26%, is the best predictor of the saturated ^<span class="hlt">26</span><span class="hlt">Al</span> content of a stony meteorite. We find no evidence of bias or crippling multicollinearity in this expression. About one half of the remaining variability cannot be attributed to uncertainties in the determination of the ^<span class="hlt">26</span><span class="hlt">Al</span> content and thus must be attributed to variations in orbit, shielding, etc. We compare our results (see figure) with those of other workers (1,2,3,4), and examine the probable causes of the disagreements displayed there. We show that saturated ^<span class="hlt">26</span><span class="hlt">Al</span> is distributed among all classes of meteorites in about the same way, with the exception of the carbonaceous chondrites and the eucrites, which both have about the same excess proportion of unsaturation. We examine the question of the convergence of expressions derived from regressions on chemical composition to the predictive expressions derived from integrals of particle fluxes and nuclear reaction cross sections and show that they need not converge. We examine the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3670341','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3670341"><span id="translatedtitle">182Hf–182W age dating of a <span class="hlt">26</span><span class="hlt">Al</span>-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Holst, Jesper C.; Olsen, Mia B.; Paton, Chad; Nagashima, Kazuhide; Schiller, Martin; Wielandt, Daniel; Larsen, Kirsten K.; Connelly, James N.; Jørgensen, Jes K.; Krot, Alexander N.; Nordlund, Åke; Bizzarro, Martin</p> <p>2013-01-01</p> <p>Refractory inclusions [calcium–aluminum-rich inclusions, (CAIs)] represent the oldest Solar System solids and provide information regarding the formation of the Sun and its protoplanetary disk. CAIs contain evidence of now extinct short-lived radioisotopes (e.g., <span class="hlt">26</span><span class="hlt">Al</span>, 41Ca, and 182Hf) synthesized in one or multiple stars and added to the protosolar molecular cloud before or during its collapse. Understanding how and when short-lived radioisotopes were added to the Solar System is necessary to assess their validity as chronometers and constrain the birthplace of the Sun. Whereas most CAIs formed with the canonical abundance of <span class="hlt">26</span><span class="hlt">Al</span> corresponding to <span class="hlt">26</span><span class="hlt">Al</span>/27Al of ∼5 × 10−5, rare CAIs with fractionation and unidentified nuclear isotope effects (FUN CAIs) record nucleosynthetic isotopic heterogeneity and <span class="hlt">26</span><span class="hlt">Al</span>/27Al of <5 × 10−6, possibly reflecting their formation before canonical CAIs. Thus, FUN CAIs may provide a unique window into the earliest Solar System, including the origin of short-lived radioisotopes. However, their chronology is unknown. Using the 182Hf–182W chronometer, we show that a FUN CAI recording a condensation origin from a solar gas formed coevally with canonical CAIs, but with <span class="hlt">26</span><span class="hlt">Al</span>/27Al of ∼3 × 10−6. The decoupling between 182Hf and <span class="hlt">26</span><span class="hlt">Al</span> requires distinct stellar origins: steady-state galactic stellar nucleosynthesis for 182Hf and late-stage contamination of the protosolar molecular cloud by a massive star(s) for <span class="hlt">26</span><span class="hlt">Al</span>. Admixing of stellar-derived <span class="hlt">26</span><span class="hlt">Al</span> to the protoplanetary disk occurred during the epoch of CAI formation and, therefore, the 26Al–26Mg systematics of CAIs cannot be used to define their formation interval. In contrast, our results support 182Hf homogeneity and chronological significance of the 182Hf–182W clock. PMID:23671077</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ApJ...763L..33G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ApJ...763L..33G"><span id="translatedtitle">Variable and Extreme Irradiation Conditions in the Early Solar System Inferred from the Initial Abundance of <span class="hlt">10</span><span class="hlt">Be</span> in Isheyevo CAIs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gounelle, Matthieu; Chaussidon, Marc; Rollion-Bard, Claire</p> <p>2013-02-01</p> <p>A search for short-lived <span class="hlt">10</span><span class="hlt">Be</span> in 21 calcium-aluminum-rich inclusions (CAIs) from Isheyevo, a rare CB/CH chondrite, showed that only 5 CAIs had 10B/11B ratios higher than chondritic correlating with the elemental ratio 9Be/11B, suggestive of in situ decay of this key short-lived radionuclide. The initial (<span class="hlt">10</span><span class="hlt">Be</span>/9Be)0 ratios vary between ~10-3 and ~10-2 for CAI 411. The initial ratio of CAI 411 is one order of magnitude higher than the highest ratio found in CV3 CAIs, suggesting that the more likely origin of CAI 411 <span class="hlt">10</span><span class="hlt">Be</span> is early solar system irradiation. The low (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 [<= 8.9 × 10-7] with which CAI 411 formed indicates that it was exposed to gradual flares with a proton fluence of a few 1019 protons cm-2, during the earliest phases of the solar system, possibly the infrared class 0. The irradiation conditions for other CAIs are less well constrained, with calculated fluences ranging between a few 1019 and 1020 protons cm-2. The variable and extreme value of the initial <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios in carbonaceous chondrite CAIs is the reflection of the variable and extreme magnetic activity in young stars observed in the X-ray domain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1811732W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1811732W"><span id="translatedtitle">Late Holocene denudation rates and sediment fluxes in the Po basin from source to sink based on in situ cosmogenic <span class="hlt">10</span><span class="hlt">Be</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wittmann, Hella; Malusà, Marco; Resentini, Alberto; Garzanti, Eduardo; Niedermann, Samuel</p> <p>2016-04-01</p> <p>We constrain the long-term sediment delivery within the Po basin from source to lowland sink using sediment fluxes from in situ <span class="hlt">10</span><span class="hlt">Be</span>-derived denudation rates and compare these to published short-term estimates from gauging. We measured in situ <span class="hlt">10</span><span class="hlt">Be</span> concentrations in nearly all Alpine and Apennine upstream catchments draining to the Po River and in the Po lowlands down to the Po delta, respectively. In the upstream reaches of the Po basin, short-term sediment interception in dams and reservoirs and long-term sediment trapping in periglacial lakes may modify <span class="hlt">10</span><span class="hlt">Be</span> concentrations, whereas in lowland reaches, sediment burial and storage may affect nuclide concentrations. From the comparison of <span class="hlt">10</span><span class="hlt">Be</span> nuclide data measured upstream of dam influence to those measured downstream of major dams, we find that the average <span class="hlt">10</span><span class="hlt">Be</span> signal is not significantly modified. In the lowland reaches, we find that the average <span class="hlt">10</span><span class="hlt">Be</span> concentration is only marginally modified by floodplain processes, as <span class="hlt">26</span><span class="hlt">Al</span>/<span class="hlt">10</span><span class="hlt">Be</span> ratios do not show differential decay due to burial and 21Ne concentrations change only slightly along the floodplain reach. Thus we interpret the average <span class="hlt">10</span><span class="hlt">Be</span> concentration of lowland samples to reflect the average <span class="hlt">10</span><span class="hlt">Be</span> concentration of all upstream catchments in terms of a preservation of the source area erosion signal. The close similarity in <span class="hlt">10</span><span class="hlt">Be</span> concentrations from the sources to the Po lowland sink suggests that LGM denudation rates prior to sediment trapping in periglacial lakes were similar to today's, as the sediment now contained in the Po lowlands must have been eroded from the orogen and deposited in the lowlands prior to lake formation. This source-sink assessment shows the robustness of cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> as erosion rate tracer. From these in situ <span class="hlt">10</span><span class="hlt">Be</span>-derived denudation rates integrating over the last few thousand years, we constrain the sediment contributions of the Alpine and Apennine source areas arriving at the Po delta. In total, ca. 60 Mt/yr of sediment are exported to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.169...99K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.169...99K"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span>-26Mg chronology and oxygen isotope distributions of multiple melting for a Type C CAI from Allende</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kawasaki, Noriyuki; Kato, Chizu; Itoh, Shoichi; Wakaki, Shigeyuki; Ito, Motoo; Yurimoto, Hisayoshi</p> <p>2015-11-01</p> <p>Disequilibrium oxygen isotopic distributions of Ca-Al-rich inclusions (CAIs) correspond to multiple melting events in the solar nebula. <span class="hlt">26</span><span class="hlt">Al</span>-26Mg systematics may be applicable for age differences among such melting events. We have carried out a coordinated study of detailed petrographic observations and in-situ oxygen and magnesium isotope measurements for a Type C CAI, EK1-04-2, from the Allende CV3 meteorite to determine the melting events and their ages. The CAI consists mainly of spinel, anorthite, olivine, and pyroxene, and has a core and mantle structure. Petrography of the core suggests that the crystallization sequence of the core minerals is from spinel, anorthite, olivine, and to pyroxene. The mantle has the same mineral assemblage as the core, and shows incomplete melting and solidification textures. Oxygen isotopic compositions of the minerals are distributed along the carbonaceous chondrite anhydrous mineral (CCAM) line (δ18O = -44‰ to +9‰), which indicates to preserve a chemical disequilibrium status in the CAI. Spinel shows a 16O-rich signature (δ18O ∼ -43‰), while anorthite is 16O-poor (δ18O ∼ +8‰). Olivine and pyroxene in the core have the same oxygen isotopic composition (δ18O ∼ -15‰), which indicates their equilibrium. Olivine and pyroxene in the mantle have variable oxygen isotopic compositions and are slightly depleted in 16O (δ18O = -13‰ to -4‰) compared with the same minerals in the core. The <span class="hlt">26</span><span class="hlt">Al</span>-26Mg systematics is consistent with the disequilibrium status observed according to the petrography and oxygen isotopes. Spinel is plotted on a line of (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 = (3.5 ± 0.2) × 10-5, anorthite is plotted on a line of (-1 ± 5) × 10-7, and olivine and pyroxene in the core are plotted on a line of (-1 ± 7) × 10-6. Plots of olivine and pyroxene in the mantle are scattered below the isochron of these minerals in the core. This study indicates that the EK1-04-2 Type C CAI underwent multiple heating events after the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/756734','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/756734"><span id="translatedtitle">Update on terrestrial ages of Antarctic meteorites</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Welten, K C; Nishiizumi, K; Caffee, M W</p> <p>2000-01-14</p> <p>Terrestrial ages of Antarctic meteorites are one of the few parameters that will help us to understand the meteorite concentration mechanism on blue-ice fields. Traditionally, terrestrial ages were determined on the basis of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> in the metal phase, which has an uncertainty of about 70 ky. For young meteorites (< 40 ky), the terrestrial age is usually and most accurately determined using {sup 14}C in the stone phase. In recent years two methods have been developed which are independent of shielding effects, the {sup <span class="hlt">10</span>}<span class="hlt">Be</span>-{sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/{sup <span class="hlt">10</span>}<span class="hlt">Be</span> method and the {sup 41}Ca/{sup <span class="hlt">36</span>}<span class="hlt">Cl</span> method. These methods have reduced the typical uncertainties in terrestrial ages by a factor of 2, to about 30 ky. The {sup <span class="hlt">10</span>}<span class="hlt">Be</span>-{sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/{sup <span class="hlt">10</span>}<span class="hlt">Be</span> method is quite dependent on the exposure age, which is unknown for most Antarctic meteorites. The authors therefore also attempt to use the relation between {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/{sup <span class="hlt">26</span>}<span class="hlt">Al</span> to derive a terrestrial age less dependent on the exposure age. The authors have measured the concentrations of cosmogenic {sup <span class="hlt">10</span>}<span class="hlt">Be</span>, {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> in the metal phase of {approximately} 70 Antarctic meteorites, from more than 10 different ice-fields, including many new ones. They then discuss the trends in terrestrial ages of meteorites from different ice-fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22167129','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22167129"><span id="translatedtitle">IMPACT OF A REVISED {sup 25}Mg(p, {gamma}){sup <span class="hlt">26</span>}<span class="hlt">Al</span> REACTION RATE ON THE OPERATION OF THE Mg-Al CYCLE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Straniero, O.; Cristallo, S.; Imbriani, G.; DiLeva, A.; Limata, B.; Strieder, F.; Bemmerer, D.; Broggini, C.; Caciolli, A.; Corvisiero, P.; Costantini, H.; Lemut, A.; Formicola, A.; Gustavino, C.; Junker, M.; Elekes, Z.; Fueloep, Zs.; Gyuerky, Gy.; Gervino, G.; Guglielmetti, A.; and others</p> <p>2013-02-15</p> <p>Proton captures on Mg isotopes play an important role in the Mg-Al cycle active in stellar H-burning regions. In particular, low-energy nuclear resonances in the {sup 25}Mg(p, {gamma}){sup <span class="hlt">26</span>}<span class="hlt">Al</span> reaction affect the production of radioactive {sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup gs} as well as the resulting Mg/Al abundance ratio. Reliable estimations of these quantities require precise measurements of the strengths of low-energy resonances. Based on a new experimental study performed at the Laboratory for Underground Nuclear Astrophysics, we provide revised rates of the {sup 25}Mg(p, {gamma}){sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup gs} and the {sup 25}Mg(p, {gamma}){sup <span class="hlt">26</span>}<span class="hlt">Al</span> {sup m} reactions with corresponding uncertainties. In the temperature range 50-150 MK, the new recommended rate of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> {sup m} production is up to five times higher than previously assumed. In addition, at T = 100 MK, the revised total reaction rate is a factor of two higher. Note that this is the range of temperature at which the Mg-Al cycle operates in a H-burning zone. The effects of this revision are discussed. Due to the significantly larger {sup 25}Mg(p, {gamma}){sup <span class="hlt">26</span>}<span class="hlt">Al</span> {sup m} rate, the estimated production of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup gs} in H-burning regions is less efficient than previously obtained. As a result, the new rates should imply a smaller contribution from Wolf-Rayet stars to the galactic {sup <span class="hlt">26</span>}<span class="hlt">Al</span> budget. Similarly, we show that the asymptotic giant branch (AGB) extra-mixing scenario does not appear able to explain the most extreme values of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al, i.e., >10{sup -2}, found in some O-rich presolar grains. Finally, the substantial increase of the total reaction rate makes the hypothesis of self-pollution by massive AGBs a more robust explanation for the Mg-Al anticorrelation observed in globular-cluster stars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.8385S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.8385S"><span id="translatedtitle">Morphogenetic evolution of the Têt river valley (eastern Pyrenees) using <span class="hlt">10</span><span class="hlt">Be</span>/21Ne cosmogenic burial dating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sartégou, Amandine; Blard, Pierre-Henri; Braucher, Régis; Bourlès, Didier L.; Calvet, Marc; Zimmermann, Laurent; Tibari, Bouchaïb; Hez, Gabriel; Gunnell, Yanni; Aumaitre, Georges; Keddadouche, Karim</p> <p>2016-04-01</p> <p>The rates and chronologies of valley incision are closely modulated by the tectonic uplift of active mountain ranges and were controlled by repeated climate changes during the Quaternary. The continental collision between the Iberian and Eurasian plates induced a double vergence orogen, the Pyrenees, which has been considered as a mature mountain range in spite of significant seismicity (e.g. Chevrot et al., 2011) and evidence of neotectonics (e.g. Goula et al., 1999). Nevertheless, recent studies indicate that the range may have never reached a steady state (Ford et al., in press). One option for resolving this controversy is to quantify the incision rates since the Miocene by reconstructing the vertical movement of geometric markers such as fluvial terraces. However, the few available ages from the Pyrenean terrace systems do not exceed the middle Pleistocene. Thus, to enlarge the time span of this dataset, we studied alluvium-filled horizontal epiphreatic passages in limestone karstic networks. Such landforms are used as substitutes of fluvial terraces because they represent former valley floors (e.g. Palmer, 2007; Audra et al., 2013). They record the transient position of former local base levels during the process of valley deepening. The Têt river valley (southern Pyrenees) was studied near the Villefranche-de-Conflent limestone gorge where 8 cave levels have been recognized over a vertical height of 600 meters. Given that <span class="hlt">26</span><span class="hlt">Al</span>/<span class="hlt">10</span><span class="hlt">Be</span> cosmogenic burial dating in this setting was limited to the last ~5 Ma (Calvet et al., 2015), here we used the cosmogenic <span class="hlt">10</span><span class="hlt">Be</span>/21Ne method in order to restore a more complete chronology of valley incision (e.g. Balco & Shuster, 2009; McPhilipps et al., 2016). Burial age results for alluvial deposits from 12 caves document incision rates since the Langhian (~14 Ma). Preliminary results indicate a history of valley deepening in successive stages. The data show a regular incision rate of 70-80 mm/a from the Langhian to the Messinian</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016QSRv..140..142S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016QSRv..140..142S&link_type=ABSTRACT"><span id="translatedtitle">Authigenic <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios and <span class="hlt">10</span><span class="hlt">Be</span>-fluxes (230Thxs-normalized) in central Baffin Bay sediments during the last glacial cycle: Paleoenvironmental implications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Simon, Quentin; Thouveny, Nicolas; Bourlès, Didier L.; Nuttin, Laurence; Hillaire-Marcel, Claude; St-Onge, Guillaume</p> <p>2016-05-01</p> <p>Authigenic <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios and <span class="hlt">10</span><span class="hlt">Be</span>-fluxes reconstructed using the 230Thxs normalization, proxies of the cosmogenic radionuclide <span class="hlt">10</span><span class="hlt">Be</span> production rate in the atmosphere, have been measured in a sedimentary core from Baffin Bay (North Atlantic) spanning the last 136 ka BP. The normalization applied on the exchangeable (authigenic) <span class="hlt">10</span><span class="hlt">Be</span> concentrations using the authigenic 9Be isotope and 230Thxs methods yield equivalent results strongly correlated with sedimentological parameters (grain-size and mineralogy). Lower authigenic beryllium (Be) concentrations and <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios are associated with coarse-grained carbonate-rich layers, while higher authigenic Be values are related to fine-grained felspar-rich sediments. This variability is due to: i) sediment composition control over beryllium-scavenging efficiency and, ii) glacial history that contributed to modify the <span class="hlt">10</span><span class="hlt">Be</span> concentration in Baffin Bay by input and boundary scavenging condition changes. Most paleo-denudation rates inferred from the <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio vary weakly around 220 ± 76 tons.km-2.yr-1 (0.09 ± 0.03 mm.yr-1) corresponding to relatively steady weathering fluxes over the last glacial cycle except for six brief intervals characterized by sharp increases of the denudation rate. These intervals are related to ice-surging episodes coeval with Heinrich events and the last deglaciation period. An average freshwater flux of 180.6 km3.yr-1 (0.006 Sv), consistent with recent models, has been calculated in order to sustain glacially-derived <span class="hlt">10</span><span class="hlt">Be</span> inputs into Baffin Bay. It is concluded that in such environments, the authigenic <span class="hlt">10</span><span class="hlt">Be</span> measured mainly depends on climatic effects related to the glacial dynamics, which masks the <span class="hlt">10</span><span class="hlt">Be</span> production variation modulated by geomagnetic field changes. Altogether, these results challenge the simple interpretation of <span class="hlt">10</span><span class="hlt">Be</span>-concentration variation as a proxy of Interglacial/Glacial (interstadial/stadial) cycles in Arctic and sub-Arctic regions. They rather suggest the effect</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016QSRv..140..142S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016QSRv..140..142S"><span id="translatedtitle">Authigenic <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios and <span class="hlt">10</span><span class="hlt">Be</span>-fluxes (230Thxs-normalized) in central Baffin Bay sediments during the last glacial cycle: Paleoenvironmental implications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Simon, Quentin; Thouveny, Nicolas; Bourlès, Didier L.; Nuttin, Laurence; Hillaire-Marcel, Claude; St-Onge, Guillaume</p> <p>2016-05-01</p> <p>Authigenic <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios and <span class="hlt">10</span><span class="hlt">Be</span>-fluxes reconstructed using the 230Thxs normalization, proxies of the cosmogenic radionuclide <span class="hlt">10</span><span class="hlt">Be</span> production rate in the atmosphere, have been measured in a sedimentary core from Baffin Bay (North Atlantic) spanning the last 136 ka BP. The normalization applied on the exchangeable (authigenic) <span class="hlt">10</span><span class="hlt">Be</span> concentrations using the authigenic 9Be isotope and 230Thxs methods yield equivalent results strongly correlated with sedimentological parameters (grain-size and mineralogy). Lower authigenic beryllium (Be) concentrations and <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios are associated with coarse-grained carbonate-rich layers, while higher authigenic Be values are related to fine-grained felspar-rich sediments. This variability is due to: i) sediment composition control over beryllium-scavenging efficiency and, ii) glacial history that contributed to modify the <span class="hlt">10</span><span class="hlt">Be</span> concentration in Baffin Bay by input and boundary scavenging condition changes. Most paleo-denudation rates inferred from the <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio vary weakly around 220 ± 76 tons.km-2.yr-1 (0.09 ± 0.03 mm.yr-1) corresponding to relatively steady weathering fluxes over the last glacial cycle except for six brief intervals characterized by sharp increases of the denudation rate. These intervals are related to ice-surging episodes coeval with Heinrich events and the last deglaciation period. An average freshwater flux of 180.6 km3.yr-1 (0.006 Sv), consistent with recent models, has been calculated in order to sustain glacially-derived <span class="hlt">10</span><span class="hlt">Be</span> inputs into Baffin Bay. It is concluded that in such environments, the authigenic <span class="hlt">10</span><span class="hlt">Be</span> measured mainly depends on climatic effects related to the glacial dynamics, which masks the <span class="hlt">10</span><span class="hlt">Be</span> production variation modulated by geomagnetic field changes. Altogether, these results challenge the simple interpretation of <span class="hlt">10</span><span class="hlt">Be</span>-concentration variation as a proxy of Interglacial/Glacial (interstadial/stadial) cycles in Arctic and sub-Arctic regions. They rather suggest the effect of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.110..190M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.110..190M"><span id="translatedtitle">Heterogeneous distribution of <span class="hlt">26</span><span class="hlt">Al</span> at the birth of the Solar System: Evidence from corundum-bearing refractory inclusions in carbonaceous chondrites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Makide, Kentaro; Nagashima, Kazuhide; Krot, Alexander N.; Huss, Gary R.; Hutcheon, Ian D.; Hellebrand, Eric; Petaev, Michail I.</p> <p>2013-06-01</p> <p>We report on the mineralogy, petrology, and in situ oxygen- and magnesium-isotope measurements using secondary ion mass spectrometry of 10 corundum-bearing calcium-aluminum-rich inclusions (CAIs) from the Adelaide (ungrouped), Murray and Murchison (CM) carbonaceous chondrites. We also measured in situ oxygen-isotope compositions of several isolated corundum grains in the matrices of Murray and Murchison. Most of the corundum-bearing objects studied are uniformly 16O-rich [Δ17O values range from -17‰ to -28‰ (2σ = ±2.5‰) (Δ17Oavr = -23 ± 5‰)], suggesting that they formed in a 16O-rich gas of approximately solar composition and largely avoided subsequent thermal processing in an 16O-poor gaseous reservoir. There is a large spread of the initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio [(<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0] in the corundum-bearing CAIs. Two Adelaide CAIs show no resolvable excess of radiogenic 26Mg (δ26Mg∗): the inferred (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 are (0.6 ± 2.0) × 10-6 and (-0.9 ± 1.2) × 10-6, respectively. Slopes of the model <span class="hlt">26</span><span class="hlt">Al</span>-26Mg isochrons in five CAIs from Murray and Murchison are (4.4 ± 0.2) × 10-5, (3.3 ± 0.3) × 10-5, (4.1 ± 0.3) × 10-5, (3.9 ± 0.4) × 10-5, and (4.0 ± 2.0) × 10-6, respectively. These values are lower than the canonical (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 ratio of (5.23 ± 0.13) × 10-5 inferred from the whole-rock magnesium-isotope measurements of the CV CAIs, but similar to the (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 ratio of (4.1 ± 0.2) × 10-5 in the corundum-bearing CAI F5 from Murray. Five other previously studied corundum-bearing CAIs from Acfer 094 (ungrouped) and CM carbonaceous chondrites showed no resolvable δ26Mg∗. We conclude that the corundum-bearing CAIs, as well as the solar corundum grains from matrices and acid-resistant residues of unequilibrated ordinary and carbonaceous chondrites, recorded heterogeneous distribution of <span class="hlt">26</span><span class="hlt">Al</span> in the Solar System during an epoch of CAI formation. The <span class="hlt">26</span><span class="hlt">Al</span>-rich and <span class="hlt">26</span><span class="hlt">Al</span>-poor corundum-bearing CAIs and solar corundum grains represent different</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014HydJ...22.1359K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014HydJ...22.1359K"><span id="translatedtitle">Testing the 14C ages and conservative behavior of dissolved 14C in a carbonate aquifer in Yucca Flat, Nevada (USA), using <span class="hlt">36</span><span class="hlt">Cl</span> from groundwater and packrat middens</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kwicklis, Edward; Farnham, Irene</p> <p>2014-09-01</p> <p>Corrected groundwater 14C ages from the carbonate aquifer in Yucca Flat at the former Nevada Test Site (now the Nevada National Security Site), USA, were evaluated by comparing temporal variations of groundwater <span class="hlt">36</span><span class="hlt">Cl</span>/Cl estimated with these 14C ages with published records of meteoric <span class="hlt">36</span><span class="hlt">Cl</span>/Cl variations preserved in packrat middens (piles of plant fragments, fecal matter and urine). Good agreement between these records indicates that the groundwater 14C ages are reasonable and that 14C is moving with chloride without sorbing to the carbonate rock matrix or fracture coatings, despite opposing evidence from laboratory experiments. The groundwater 14C ages are consistent with other hydrologic evidence that indicates significant basin infiltration ceased 8,000 to 10,000 years ago, and that recharge to the carbonate aquifer is from paleowater draining through overlying tuff confining units along major faults. This interpretation is supported by the relative age differences as well as hydraulic head differences between the alluvial and volcanic aquifers and the carbonate aquifer. The carbonate aquifer 14C ages suggest that groundwater velocities throughout much of Yucca Flat are about 2 m/yr, consistent with the long-held conceptual model that blocking ridges of low-permeability rock hydrologically isolate the carbonate aquifer in Yucca Flat from the outlying regional carbonate flow system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JPhG...39j5201D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JPhG...39j5201D"><span id="translatedtitle">44Ti, <span class="hlt">26</span><span class="hlt">Al</span> and 53Mn samples for nuclear astrophysics: the needs, the possibilities and the sources</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dressler, R.; Ayranov, M.; Bemmerer, D.; Bunka, M.; Dai, Y.; Lederer, C.; Fallis, J.; StJ Murphy, A.; Pignatari, M.; Schumann, D.; Stora, T.; Stowasser, T.; Thielemann, F.-K.; Woods, P. J.</p> <p>2012-10-01</p> <p>Exploration of the physics involved in the production of cosmogenic radionuclides requires experiments using the same rare, radioactive nuclei in sufficient quantities. For this work, such exotic radionuclides have been extracted from previously proton-irradiated stainless steel samples using wet chemistry separation techniques. The irradiated construction material has arisen from an extended material research programme at the Paul Scherrer Institute, called STIP (SINQ Target Irradiation Program), where several thousand samples of different materials were irradiated with protons and neutrons of energies up to 570 MeV. In total, 8 × 1017 atoms of 44Ti, ˜1016 atoms of <span class="hlt">26</span><span class="hlt">Al</span> and ˜1019 atoms of 53Mn are available from selected samples. These materials may now be used to produce targets or radioactive beams for nuclear reaction studies with protons, neutrons and α-particles. The work is part of the ERAWAST initiative (Exotic Radionuclides from Accelerator Waste for Science and Technology), aimed at facilitating new collaborations between the isotope producers and users from different scientific fields including nuclear astrophysics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010GeCoA..74.6814G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010GeCoA..74.6814G"><span id="translatedtitle">Meteoric <span class="hlt">10</span><span class="hlt">Be</span> in soil profiles - A global meta-analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Graly, Joseph A.; Bierman, Paul R.; Reusser, Lucas J.; Pavich, Milan J.</p> <p>2010-12-01</p> <p>In order to assess current understanding of meteoric <span class="hlt">10</span><span class="hlt">Be</span> dynamics and distribution in terrestrial soils, we assembled a database of all published meteoric <span class="hlt">10</span><span class="hlt">Be</span> soil depth profiles, including 104 profiles from 27 studies in globally diverse locations, collectively containing 679 individual measurements. This allows for the systematic comparison of meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentration to other soil characteristics and the comparison of profile depth distributions between geologic settings. Percent clay, 9Be, and dithionite-citrate extracted Al positively correlate to meteoric <span class="hlt">10</span><span class="hlt">Be</span> in more than half of the soils where they were measured, but the lack of significant correlation in other soils suggests that no one soil factor controls meteoric <span class="hlt">10</span><span class="hlt">Be</span> distribution with depth. Dithionite-citrate extracted Fe and cation exchange capacity are only weakly correlated to meteoric <span class="hlt">10</span><span class="hlt">Be</span>. Percent organic carbon and pH are not significantly related to meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentration when all data are complied. The compilation shows that meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentration is seldom uniform with depth in a soil profile. In young or rapidly eroding soils, maximum meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations are typically found in the uppermost 20 cm. In older, more slowly eroding soils, the highest meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations are found at depth, usually between 50 and 200 cm. We find that the highest measured meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentration in a soil profile is an important metric, as both the value and the depth of the maximum meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentration correlate with the total measured meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventory of the soil profile. In order to refine the use of meteoric <span class="hlt">10</span><span class="hlt">Be</span> as an estimator of soil erosion rate, we compare near-surface meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations to total meteoric <span class="hlt">10</span><span class="hlt">Be</span> soil inventories. These trends are used to calibrate models of meteoric <span class="hlt">10</span><span class="hlt">Be</span> loss by soil erosion. Erosion rates calculated using this method vary based on the assumed depth and timing of erosional events and on the reference data selected.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70037648','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70037648"><span id="translatedtitle">Meteoric <span class="hlt">10</span><span class="hlt">Be</span> in soil profiles - A global meta-analysis</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Graly, Joseph A.; Bierman, Paul R.; Reusser, Lucas J.; Pavich, Milan J.</p> <p>2010-01-01</p> <p>In order to assess current understanding of meteoric <span class="hlt">10</span><span class="hlt">Be</span> dynamics and distribution in terrestrial soils, we assembled a database of all published meteoric <span class="hlt">10</span><span class="hlt">Be</span> soil depth profiles, including 104 profiles from 27 studies in globally diverse locations, collectively containing 679 individual measurements. This allows for the systematic comparison of meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentration to other soil characteristics and the comparison of profile depth distributions between geologic settings. Percent clay, 9Be, and dithionite-citrate extracted Al positively correlate to meteoric <span class="hlt">10</span><span class="hlt">Be</span> in more than half of the soils where they were measured, but the lack of significant correlation in other soils suggests that no one soil factor controls meteoric <span class="hlt">10</span><span class="hlt">Be</span> distribution with depth. Dithionite-citrate extracted Fe and cation exchange capacity are only weakly correlated to meteoric <span class="hlt">10</span><span class="hlt">Be</span>. Percent organic carbon and pH are not significantly related to meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentration when all data are complied.The compilation shows that meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentration is seldom uniform with depth in a soil profile. In young or rapidly eroding soils, maximum meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations are typically found in the uppermost 20 cm. In older, more slowly eroding soils, the highest meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations are found at depth, usually between 50 and 200 cm. We find that the highest measured meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentration in a soil profile is an important metric, as both the value and the depth of the maximum meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentration correlate with the total measured meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventory of the soil profile.In order to refine the use of meteoric <span class="hlt">10</span><span class="hlt">Be</span> as an estimator of soil erosion rate, we compare near-surface meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations to total meteoric <span class="hlt">10</span><span class="hlt">Be</span> soil inventories. These trends are used to calibrate models of meteoric <span class="hlt">10</span><span class="hlt">Be</span> loss by soil erosion. Erosion rates calculated using this method vary based on the assumed depth and timing of erosional events and on the reference data selected.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V31G..09C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V31G..09C"><span id="translatedtitle">The Gas-Filled-Magnet at PRIME Lab: Increased Sensitivity of Cosmogenic Nuclide Measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caffee, M. W.; Granger, D. E.; Woodruff, T. E.</p> <p>2015-12-01</p> <p>Abstract: Using accelerator mass spectrometry (AMS), radionuclides produced either by cosmic-ray interactions or by nucleogenic means can be measured. Typical isotopic abundance ratios range from 1 x 10-10 to 1 x 10-15. The routinely measured radionuclides are <span class="hlt">10</span><span class="hlt">Be</span>, 14C, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, and 129I. Be-10, <span class="hlt">26</span><span class="hlt">Al</span>, and <span class="hlt">36</span><span class="hlt">Cl</span> have isobaric interferences that cannot be eliminated mass through mass analysis, but dE/dx techniques suppresses these isobars enough to allow successful measurements. There are compromises, the isobar for <span class="hlt">26</span><span class="hlt">Al</span>, 26Mg, precludes successful measurement of <span class="hlt">26</span><span class="hlt">Al</span> if AlO- is injected into the accelerator. Mg- doesn't form a stable negative ion so a <span class="hlt">26</span><span class="hlt">Al</span> measurement requires injection of <span class="hlt">26</span><span class="hlt">Al</span>-. But the Al- ion is formed inefficiently; secondary ion currents using Al- are ~ 10 times less than an AlO- secondary ion beam. Precision scales with count rate so precise measurement of the <span class="hlt">26</span><span class="hlt">Al</span>/Al for all but higher ratio samples is difficult. It has long been recognized that a gas-filled-magnet (GFM) could potentially improve the measurement of those radionuclides with intractable isobar interferences. A GFM works on the principle that each element of an isobar pair, e.g. 26Mg and <span class="hlt">26</span><span class="hlt">Al</span>, has a different average charge state as it traverses a gas (3-4 Torr of N2) contained within the vacuum jacket of a magnet. The magnet steers each species with its own momentum-to-charge ratio on its own distinct radius of curvature. The magnet can be tuned to allow the isotope of interest into a dE/dx detector; most of the isobar doesn't make it into the detector. Using the PRIME Lab GFM we are now able to routinely run <span class="hlt">26</span><span class="hlt">Al</span> with a precision that is comparable to that obtained with <span class="hlt">10</span><span class="hlt">Be</span>. We are also using the GFM for routine measurements of <span class="hlt">10</span><span class="hlt">Be</span> and <span class="hlt">36</span><span class="hlt">Cl</span>. Although the improvement for these nuclides is not as pronounced as it is for <span class="hlt">26</span><span class="hlt">Al</span>, the GFM has improved the detection sensitivity for both. Our <span class="hlt">10</span><span class="hlt">Be</span> background is now ~ 5 x 10-16 and for <span class="hlt">36</span><span class="hlt">Cl</span> we can now run the source more</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010ApJ...725..443B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010ApJ...725..443B"><span id="translatedtitle">Solar Wind Implantation Model for <span class="hlt">10</span><span class="hlt">Be</span> in Calcium-Aluminum Inclusions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bricker, Glynn E.; Caffee, Marc W.</p> <p>2010-12-01</p> <p>We propose a model for the incorporation of <span class="hlt">10</span><span class="hlt">Be</span> within calcium-aluminum inclusions (CAIs) in primitive carbonaceous meteorites. In this model, <span class="hlt">10</span><span class="hlt">Be</span> is produced by energetic particle reactions in the proto-solar atmosphere of a more active proto-Sun characterized by energetic particle fluxes higher than contemporary particle fluxes. This <span class="hlt">10</span><span class="hlt">Be</span> is incorporated into the solar wind that is then implanted into CAI precursor material. This production mechanism is operational in the contemporary solar system implanting <span class="hlt">10</span><span class="hlt">Be</span> in lunar materials. The contemporary production rate of <span class="hlt">10</span><span class="hlt">Be</span> at the surface of the Sun is ~0.1 <span class="hlt">10</span><span class="hlt">Be</span> cm-2 s-1. Scaling up the contemporary <span class="hlt">10</span><span class="hlt">Be</span> production in the proto-Sun by a factor of 105 would increase the production rate to 104 <span class="hlt">10</span><span class="hlt">Be</span> cm-2 s-1. Using this enhanced production value in conjunction with refractory mass inflow rates at 0.06 AU from the proto-Sun we model <span class="hlt">10</span><span class="hlt">Be</span> concentrations in CAI precursors. We calculate the content of solar-wind-implanted <span class="hlt">10</span><span class="hlt">Be</span> would have been of the order of 1012 <span class="hlt">10</span><span class="hlt">Be</span> g-1 in CAIs, consistent with initial<span class="hlt">10</span><span class="hlt">Be</span> content found from boron-beryllium isotopic systematics in CAIs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011E%26PSL.302..329G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011E%26PSL.302..329G"><span id="translatedtitle">Short and long-term delivery rates of meteoric <span class="hlt">10</span><span class="hlt">Be</span> to terrestrial soils</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Graly, Joseph A.; Reusser, Lucas J.; Bierman, Paul R.</p> <p>2011-02-01</p> <p>Well-constrained, long-term average meteoric <span class="hlt">10</span><span class="hlt">Be</span> deposition rates are important when meteoric <span class="hlt">10</span><span class="hlt">Be</span> is used as a chronometer or tracer of Earth surface processes. To constrain meteoric <span class="hlt">10</span><span class="hlt">Be</span> delivery to terrestrial soils, we estimate time-integrated <span class="hlt">10</span><span class="hlt">Be</span> deposition rates from meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories measured in dated soils and compare these results to a new synthesis of short-term measurements of <span class="hlt">10</span><span class="hlt">Be</span> in precipitation. Comparison of these long-term rates to short-term measurements suggests that short-term measurements likely predict long-term meteoric <span class="hlt">10</span><span class="hlt">Be</span> deposition rates within uncertainties of ~ 20%. In precipitation measurements, it is possible to deconvolve the contribution of atmospherically-produced "primary" meteoric <span class="hlt">10</span><span class="hlt">Be</span> from "recycled" meteoric <span class="hlt">10</span><span class="hlt">Be</span> delivered by terrestrial dust if a second isotope is measured that quantifies either the recycled or primary components of meteoric <span class="hlt">10</span><span class="hlt">Be</span> deposition. We use dust-concentration dependent differences between 7Be and <span class="hlt">10</span><span class="hlt">Be</span> measurements to make new estimates of the recycled contribution to total meteoric <span class="hlt">10</span><span class="hlt">Be</span> flux delivered to the Earth's surface. These dust-corrected data show a strong linear dependence between precipitation amount and primary meteoric <span class="hlt">10</span><span class="hlt">Be</span> flux. Concentrations of primary meteoric <span class="hlt">10</span><span class="hlt">Be</span> in mid- and low-latitude precipitation vary predictably by latitude between 0.63 · 10 4 and 2.05 · 10 4 atoms/cm 3 of precipitation, providing a first-order estimate of primary meteoric <span class="hlt">10</span><span class="hlt">Be</span> deposition for a given latitude and precipitation rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012GeCoA..77..415B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012GeCoA..77..415B"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span>- 26Mg deficit dating ultramafic meteorites and silicate planetesimal differentiation in the early Solar System?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baker, Joel A.; Schiller, Martin; Bizzarro, Martin</p> <p>2012-01-01</p> <p>Meteorites with significantly sub-chondritic Al/Mg that formed in the first 2 million years of the Solar System should be characterised by deficits in the abundance of 26Mg (δ26Mg∗) due to the absence of in-growth of 26Mg from the decay of short-lived <span class="hlt">26</span><span class="hlt">Al</span> (t1/2 = 0.73 Myr). However, these 26Mg deficits will be small (δ26Mg∗ >-0.037‰) even for material that formed at the same time as the Solar System’s oldest solids - calcium-aluminium-rich inclusions - and thus measurement of these deficits is analytically challenging. Here, we report on a search for 26Mg deficits in three types of ultramafic meteorites (pallasites, ureilites and aubrites) by multiple-collector inductively coupled plasma mass spectrometry. A range of analytical tests were carried out including analysis of: (1) a range of synthetic Mg solution standards; (2) Mg gravimetrically doped with a high purity 26Mg spike; (3) Mg cuts collected sequentially from cation exchange separation columns with fractionated stable Mg isotope compositions; (4) Mg separated from samples that was bracketed by analyses of both DSM-3 and Mg separated from a natural olivine sample subjected to the same chemical processing as the samples. These tests confirm it is possible to resolve differences in δ26Mg∗ from the terrestrial materials that are ⩽0.005‰. However, if Mg yields from chemical separation are low or an inappropriate equilibrium-isotopically fractionated standard is used this will generate analytical artefacts on δ26Mg∗ when this is calculated with the kinetic/exponential mass fractionation law as is the case when correcting for instrumental mass bias during mass spectrometric analysis. Olivine from four different main group pallasites and four bulk ureilites have small deficits in the abundance of 26Mg with δ26MgDSM-3∗=-0.0120±0.0018‰ and δ26MgDSM-3∗=-0.0062±0.0023‰, respectively, relative to terrestrial olivine (δ26MgDSM-3∗=+0.0029±0.0028‰). Six aubrites have δ26MgDSM-3</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21474398','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21474398"><span id="translatedtitle">SOLAR WIND IMPLANTATION MODEL FOR {sup <span class="hlt">10</span>}<span class="hlt">Be</span> IN CALCIUM-ALUMINUM INCLUSIONS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bricker, Glynn E.; Caffee, Marc W. E-mail: mcaffee@purdue.ed</p> <p>2010-12-10</p> <p>We propose a model for the incorporation of {sup <span class="hlt">10</span>}<span class="hlt">Be</span> within calcium-aluminum inclusions (CAIs) in primitive carbonaceous meteorites. In this model, {sup <span class="hlt">10</span>}<span class="hlt">Be</span> is produced by energetic particle reactions in the proto-solar atmosphere of a more active proto-Sun characterized by energetic particle fluxes higher than contemporary particle fluxes. This {sup <span class="hlt">10</span>}<span class="hlt">Be</span> is incorporated into the solar wind that is then implanted into CAI precursor material. This production mechanism is operational in the contemporary solar system implanting {sup <span class="hlt">10</span>}<span class="hlt">Be</span> in lunar materials. The contemporary production rate of {sup <span class="hlt">10</span>}<span class="hlt">Be</span> at the surface of the Sun is {approx}0.1 {sup <span class="hlt">10</span>}<span class="hlt">Be</span> cm{sup -2} s{sup -1}. Scaling up the contemporary {sup <span class="hlt">10</span>}<span class="hlt">Be</span> production in the proto-Sun by a factor of 10{sup 5} would increase the production rate to 10{sup 410}Be cm{sup -2} s{sup -1}. Using this enhanced production value in conjunction with refractory mass inflow rates at 0.06 AU from the proto-Sun we model {sup <span class="hlt">10</span>}<span class="hlt">Be</span> concentrations in CAI precursors. We calculate the content of solar-wind-implanted {sup <span class="hlt">10</span>}<span class="hlt">Be</span> would have been of the order of 10{sup 1210}Be g{sup -1} in CAIs, consistent with initial{sup <span class="hlt">10</span>}<span class="hlt">Be</span> content found from boron-beryllium isotopic systematics in CAIs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMEP53A0966C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMEP53A0966C"><span id="translatedtitle">A Numerical Model to Assess Soil Fluxes from Meteoric <span class="hlt">10</span><span class="hlt">Be</span> Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Campforts, B.; Govers, G.; Vanacker, V.; Vanderborght, J.; Smolders, E.; Baken, S.</p> <p>2015-12-01</p> <p>Meteoric <span class="hlt">10</span><span class="hlt">Be</span> may be mobile in the soil system. The latter hampers a direct translation of meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories into spatial variations in erosion and deposition rates. Here, we present a spatially explicit 2D model that allows us to simulate the behaviour of meteoric <span class="hlt">10</span><span class="hlt">Be</span> in the soil system. The Be2D model is then used to analyse the potential impact of human-accelerated soil fluxes on meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories. The model consists of two parts. A first component deals with advective and diffusive mobility of meteoric <span class="hlt">10</span><span class="hlt">Be</span> within the soil profile including particle migration, chemical leaching and bioturbation, whereas a second component describes lateral soil (and meteoric <span class="hlt">10</span><span class="hlt">Be</span>) fluxes over the hillslope. Soil depth is calculated dynamically, accounting for soil production through weathering and lateral soil fluxes from creep, water and tillage erosion. Model simulations show that meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories can indeed be related to erosion and deposition, across a wide range of geomorphological and pedological settings. However, quantification of the effects of vertical mobility is essential for a correct interpretation of the observed spatial patterns in <span class="hlt">10</span><span class="hlt">Be</span> data. Moreover, our simulations suggest that meteoric <span class="hlt">10</span><span class="hlt">Be</span> can be used as a tracer to unravel human impact on soil fluxes when soils have a high retention capacity for meteoric meteoric <span class="hlt">10</span><span class="hlt">Be</span>. Application of the Be2D model to existing data sets shows that model parameters can reliably be constrained, resulting in a good agreement between simulated and observed meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations and inventories. This confirms the suitability of the Be2D model as a robust tool to underpin quantitative interpretations of spatial variability in meteoric <span class="hlt">10</span><span class="hlt">Be</span> data for eroding landscapes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMEP33B1074J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMEP33B1074J"><span id="translatedtitle">Meteoric <span class="hlt">10</span><span class="hlt">Be</span> in Lake Cores as a Measure of Climatic and Erosional Change</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jensen, R. E.; Dixon, J. L.</p> <p>2015-12-01</p> <p>Utilization of meteoric <span class="hlt">10</span><span class="hlt">Be</span> as a paleoenvironmental proxy has the potential to offer new insights into paleoprecipitation records and paleoclimate models, as well as to long-term variations in erosion with climate. The delivery of meteoric <span class="hlt">10</span><span class="hlt">Be</span> to the surface varies with precipitation and its strong adsorption to sediment has already proven useful in studies of erosion. Thus, it is likely meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations in lake sediments vary under both changing climate and changing sediment influx. Assessment of the relative importance of these changes requires the comparison of <span class="hlt">10</span><span class="hlt">Be</span> concentrations in well-dated lake cores with independent paleoenvironmental proxies, including oxygen isotope, pollen, and charcoal records, as well as variation in geochemical composition of the sediments. Blacktail Pond details 15,000 years of climatic change in the Yellowstone region. We develop a new model framework for predicting meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations with depth in the core, based on sedimentation rates of both lake-derived and terrigenous sediments and changes in the flux of meteoric <span class="hlt">10</span><span class="hlt">Be</span> with precipitation. Titanium concentrations and previously determined <span class="hlt">10</span><span class="hlt">Be</span> concentrations in wind-derived loess provide proxies for changing delivery of <span class="hlt">10</span><span class="hlt">Be</span> to the lake by terrigenous sources. We use existing paleoenvironmental data obtained from this core and the surrounding region to develop models for changing rainfall across the region and predict meteoric <span class="hlt">10</span><span class="hlt">Be</span> delivery to the lake by precipitation. Based on a suite of ~10 models, sedimentation rate is the primary control of meteoric <span class="hlt">10</span><span class="hlt">Be</span> in the Blacktail Pond core unless terrestrial input is very high, as it was post-glacial in the early Holocene when the lake experienced a high influx of loess and terrigenous sediments. We used these models to inform sample selection for <span class="hlt">10</span><span class="hlt">Be</span> analysis along the Blacktail pond core. Core sediments are processed for meteoric <span class="hlt">10</span><span class="hlt">Be</span> analysis using sequential digestions and standard extraction procedures</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1018000','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1018000"><span id="translatedtitle">Formation of short-lived radionuclides in the protoplanetary disk during late-stage irradiation of a volatile-rich reservoir</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jacobsen, B; Matzel, J; Hutcheon, I D; Krot, A N; Yin, Q -; Nagashima, K; Ramon, E; Weber, P; Ishii, H; Ciesla, F</p> <p>2010-11-30</p> <p>The origin of short-lived (t{sub 1/2} < 5 Myr) and now extinct radionuclides ({sup <span class="hlt">10</span>}<span class="hlt">Be</span>, {sup <span class="hlt">26</span>}<span class="hlt">Al</span>, {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, {sup 41}Ca, {sup 53}Mn, {sup 60}Fe; hereafter SLRs) is fundamental to understanding the formation of the early solar system. Two distinct classes of models have been proposed to explain the origin of SLRs: (1) injection from a nearby stellar source (e.g., supernova, asymptotic giant branch star or Wolf-Rayet star) and (2) solar energetic particle irradiation of dust and gas near the proto-Sun. Recent studies have demonstrated that {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> was extant in the early solar system. However, its presence, initial abundance and the noticeable decoupling from {sup <span class="hlt">26</span>}<span class="hlt">Al</span> raise serious questions about the origin of SLRs. Here we report {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>-{sup 36}S and {sup <span class="hlt">26</span>}<span class="hlt">Al</span>-{sup 26}Mg systematics for wadalite and grossular, secondary minerals in a calcium-aluminum-rich inclusion (CAI) from the CV chondrite Allende that allow us to reassess the origin of SLRs. The inferred abundance of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> in wadalite, corresponding to a {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/{sup 35}Cl ratio of (1.81 {+-} 0.13) x 10{sup -5}, is the highest {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> abundance reported in any early solar system material. The high level of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> in wadalite and the absence of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> ({sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al {le} 3.9 x 10{sup -6}) in co-existing grossular indicates that (1) {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> formed by late-stage solar energetic particle irradiation and (2) the production of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, recorded by secondary minerals, is unrelated to the origin of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and other SLRs ({sup <span class="hlt">10</span>}<span class="hlt">Be</span>, {sup 53}Mn) recorded by primary minerals of CAIs and chondrules. We conclude that <span class="hlt">36</span><span class="hlt">Cl</span> was produced by solar energetic particle irradiation of a volatile-rich reservoir in an optically thin protoplanetary disk adjacent to the accretion region of the CV chondrite parent asteroid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1814053C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1814053C"><span id="translatedtitle">A model-based evaluation of sedimentary reconstructions of <span class="hlt">10</span><span class="hlt">Be</span> production rates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carney, Lewis; Plancherel, Yves; Khatiwala, Samar; Henderson, Gideon</p> <p>2016-04-01</p> <p>Atmospheric production of <span class="hlt">10</span><span class="hlt">Be</span> is small when solar activity and, therefore, solar magnetic field and total solar irradiance are strong. Variations in solar activity affect climate and the production of other climate-relevant isotopes, such as 14C. Solar activity is thus an important variable to constrain. Since <span class="hlt">10</span><span class="hlt">Be</span> production is clearly related to solar activity and the cycle of beryllium is simpler than that of carbon, <span class="hlt">10</span><span class="hlt">Be</span> records in ice cores have been used to reconstruct total solar irradiance variability. Unfortunately, <span class="hlt">10</span><span class="hlt">Be</span> records in ice cores are not only affected by variations in atmospheric production, but are also modulated by changes in wind patterns since spatiotemporal atmospheric <span class="hlt">10</span><span class="hlt">Be</span> gradients are quite large. In that context, sedimentary <span class="hlt">10</span><span class="hlt">Be</span> records from the abyssal ocean could be of great interest: since the residence time of <span class="hlt">10</span><span class="hlt">Be</span> in the ocean is thought to be comparable to the overturning time-scale of the ocean, spatial <span class="hlt">10</span><span class="hlt">Be</span> gradients may be relatively weaker than those in the atmosphere. Under these conditions, regional oceanic variability should only weakly affect the distribution of <span class="hlt">10</span><span class="hlt">Be</span> in the ocean and local sedimentary <span class="hlt">10</span><span class="hlt">Be</span> records are expected to represent the global average <span class="hlt">10</span><span class="hlt">Be</span> production better than <span class="hlt">10</span><span class="hlt">Be</span> measured in ice cores. We here show results from a global ocean model of <span class="hlt">10</span><span class="hlt">Be</span> that we use to investigate the spatial variability of simulated sedimentary <span class="hlt">10</span><span class="hlt">Be</span> records and test the sensitivity of the <span class="hlt">10</span><span class="hlt">Be</span> sedimentary flux to uncertainties in the circulation field and in the particle chemistry of beryllium. Our ocean model is based on the Transport Matrix method. The surface <span class="hlt">10</span><span class="hlt">Be</span> input fluxes are taken from atmospheric model simulations. Our model experiments, constrained by available dissolved <span class="hlt">10</span><span class="hlt">Be</span> data, show that there exist regions in the ocean where the sedimentary <span class="hlt">10</span><span class="hlt">Be</span> flux is relatively insensitive to changes in input patterns and magnitudes, assumed particle chemistry and flux patterns, and ocean circulation. We submit that</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004NIMPB.223..596M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004NIMPB.223..596M"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> concentrations of Red soils in Southwest Japan and its possibility of dating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maejima, Y.; Matsuzaki, H.; Nakano, C.</p> <p>2004-08-01</p> <p><span class="hlt">10</span><span class="hlt">Be</span> concentrations of six Red soils distributed in Southwest Japan ranged from 0.8 × 108 to 2.7 × 109 atoms g-1, and minimum absolute ages were estimated by inventory of meteoric <span class="hlt">10</span><span class="hlt">Be</span>. The results are follows: Red soils on Toyota derived from granite (⩽25 ka), Kashii derived from Tertiary shale (⩽24 ka), Akiyoshidai derived from limestone (⩽110 ka), Okinawa Island derived from Kunigami gravel bed (⩽9 ka) and Ogasawara Island derived from agglomerate and Boninite (⩽22 and ⩽7 ka) were obtained, respectively. Soil age except with Akiyoshidai indicated younger age. It suggested that the loss of <span class="hlt">10</span><span class="hlt">Be</span> from the soil was caused by leaching of <span class="hlt">10</span><span class="hlt">Be</span> or by soil erosion, and <span class="hlt">10</span><span class="hlt">Be</span> is susceptible to leaching out from these Red soils under the humid climate condition such as Southwest Japan.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010Geomo.119...62E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010Geomo.119...62E"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> inventories in Alpine soils and their potential for dating land surfaces</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Egli, Markus; Brandová, Dagmar; Böhlert, Ralph; Favilli, Filippo; Kubik, Peter W.</p> <p>2010-07-01</p> <p>To exploit natural sedimentary archives and geomorphic landforms it is necessary to date them first. Landscape evolution of Alpine areas is often strongly related to the activities of glaciers in the Pleistocene and Holocene. At sites where no organic matter for radiocarbon dating exists and where suitable boulders for surface exposure dating (using in situ produced cosmogenic nuclides) are absent, dating of soils could give information about the timing of landscape evolution. This paper explores the applicability of soil dating using the inventory of meteoric <span class="hlt">10</span><span class="hlt">Be</span> in Alpine soils. For this purpose, a set of 6 soil profiles in the Swiss and Italian Alps was investigated. The surface at these sites had already been dated (using the radiocarbon technique or the surface exposure determination using in situ produced <span class="hlt">10</span><span class="hlt">Be</span>). Consequently, a direct comparison of the ages of the soils using meteoric <span class="hlt">10</span><span class="hlt">Be</span> and other dating techniques was made possible. The estimation of <span class="hlt">10</span><span class="hlt">Be</span> deposition rates is subject to severe limitations and strongly influences the obtained results. We tested three scenarios using a) the meteoric <span class="hlt">10</span><span class="hlt">Be</span> deposition rates as a function of the annual precipitation rate, b) a constant <span class="hlt">10</span><span class="hlt">Be</span> input for the Central Alps, and c) as b) but assuming a pre-exposure of the parent material. The obtained ages that are based on the <span class="hlt">10</span><span class="hlt">Be</span> inventory in soils and on scenario a) for the <span class="hlt">10</span><span class="hlt">Be</span> input agreed reasonably well with the age using surface exposure or radiocarbon dating. The ages obtained from soils using scenario b) produced ages that were mostly too old whereas the approach using scenario c) seemed to yield better results than scenario b). Erosion calculations can, in theory, be performed using the <span class="hlt">10</span><span class="hlt">Be</span> inventory and <span class="hlt">10</span><span class="hlt">Be</span> deposition rates. An erosion estimation was possible using scenario a) and c), but not using b). The calculated erosion rates using these scenarios seemed to be plausible with values in the range of 0-57 mm/ky. The dating of soils using <span class="hlt">10</span><span class="hlt">Be</span> has</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1710768C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1710768C"><span id="translatedtitle">Assessing soil fluxes using meteoric <span class="hlt">10</span><span class="hlt">Be</span>: development and application of the Be2D model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Campforts, Benjamin; Govers, Gerard; Vanacker, Veerle; Baken, Stijn; Smolders, Erik; Vanderborght, Jan</p> <p>2015-04-01</p> <p>Meteoric <span class="hlt">10</span><span class="hlt">Be</span> is a promising and increasingly popular tool to better understand soil fluxes at different timescales. Unlike other, more classical, methods such as the study of sedimentary archives it enables a direct coupling between eroding and deposition sites. However, meteoric <span class="hlt">10</span><span class="hlt">Be</span> can be mobilized within the soil. Therefore, spatial variations in meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories cannot directly be translated into spatial variations in erosion and sedimentation rates: a correct interpretation of measured <span class="hlt">10</span><span class="hlt">Be</span> inventories requires that both lateral and vertical movement of meteoric <span class="hlt">10</span><span class="hlt">Be</span> are accounted for. Here, we present a spatially explicit 2D model that allows to simulate the behaviour of meteoric <span class="hlt">10</span><span class="hlt">Be</span> in the soil system over timescales of up to 1 million year and use the model to investigate the impact of accelerated erosion on meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories. The model consists of two parts. A first component deals with advective and diffusive mobility within the soil profile, whereas a second component describes lateral soil (and meteoric <span class="hlt">10</span><span class="hlt">Be</span>) fluxes over the hillslope. Soil depth is calculated dynamically, accounting for soil production through weathering and lateral soil fluxes. Different types of erosion such as creep, water and tillage erosion are supported. Model runs show that natural soil fluxes can be well reconstructed based on meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories, and this for a wide range of geomorphological and pedological conditions. However, extracting signals of human impact and distinguishing them from natural soil fluxes is only feasible when the soil has a rather high retention capacity so that meteoric <span class="hlt">10</span><span class="hlt">Be</span> is retained in the top soil layer. Application of the Be2D model to an existing data set in the Appalachian Mountains [West et al.,2013] using realistic parameter values for the soil retention capacity as well as for vertical advection resulted in a good agreement between simulated and observed <span class="hlt">10</span><span class="hlt">Be</span> inventories. This confirms the robustness of the model. We</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996LPI....27..549H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996LPI....27..549H"><span id="translatedtitle">PRIME Lab Radiocarbon Measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hillegonds, D. J.; Mueller, K. A.; Ma, X.; Lipschutz, M. E.</p> <p>1996-03-01</p> <p>The Purdue Rare Isotope Measurement Laboratory (PRIME Lab) is one of three NSF national facilities for accelerator mass spectrometry (AMS), and is the only one capable of determining six cosmogenic radionuclides: <span class="hlt">10</span><span class="hlt">Be</span>, 14C, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, 41Ca, and 129I. This abstract describes the current status of the radiocarbon analysis program at PRIME Lab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.4393C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.4393C"><span id="translatedtitle">Meteoric <span class="hlt">10</span><span class="hlt">Be</span> as a tool to investigate human induced soil fluxes: a conceptual model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Campforts, Benjamin; Govers, Gerard; Vanacker, Veerle; De Vente, Joris; Boix-Fayos, Carolina; Minella, Jean; Baken, Stijn; Smolders, Erik</p> <p>2014-05-01</p> <p>The use of meteoric <span class="hlt">10</span><span class="hlt">Be</span> as a tool to understand long term landscape behavior is becoming increasingly popular. Due its high residence time, meteoric <span class="hlt">10</span><span class="hlt">Be</span> allows in principle to investigate in situ erosion rates over time scales exceeding the period studied with classical approaches such as 137Cs. The use of meteoric <span class="hlt">10</span><span class="hlt">Be</span> strongly contributes to the traditional interpretation of sedimentary archives which cannot be unequivocally coupled to sediment production and could provide biased information over longer time scales (Sadler, 1981). So far, meteoric <span class="hlt">10</span><span class="hlt">Be</span> has successfully been used in geochemical fingerprinting of sediments, to date soil profiles, to assess soil residence times and to quantify downslope soil fluxes using accumulated <span class="hlt">10</span><span class="hlt">Be</span> inventories along a hill slope. However, less attention is given to the potential use of the tracer to directly asses human induced changes in soil fluxes through deforestation, cultivation and reforestation. A good understanding of the processes governing the distribution of meteoric <span class="hlt">10</span><span class="hlt">Be</span> both within the soil profile and at landscape scale is essential before meteoric <span class="hlt">10</span><span class="hlt">Be</span> can be successfully applied to assess human impact. We developed a spatially explicit 2D-model (Be2D) in order to gain insight in meteoric <span class="hlt">10</span><span class="hlt">Be</span> movement along a hillslope that is subject to human disturbance. Be2D integrates both horizontal soil fluxes and vertical meteoric <span class="hlt">10</span><span class="hlt">Be</span> movement throughout the soil prolife. Horizontal soil fluxes are predicted using (i) well studied geomorphical laws for natural erosion and soil formation as well as (ii) human accelerated water and tillage erosion. Vertical movement of meteoric <span class="hlt">10</span><span class="hlt">Be</span> throughout the soil profile is implemented by inserting depth dependent retardation calculated using experimentally determined partition coefficients (Kd). The model was applied to different environments such as (i) the Belgian loess belt, characterized by aeolian deposits enriched in inherited meteoric <span class="hlt">10</span><span class="hlt">Be</span>, (ii) highly degraded and stony</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1211080B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1211080B"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> in ice - four decades, two ice sheets, 15 deep coring sites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Berggren, Ann-Marie; Aldahan, Ala; Possnert, Göran</p> <p>2010-05-01</p> <p>Over the last few decades, numerous studies of <span class="hlt">10</span><span class="hlt">Be</span> in ice cores from Antarctica and Greenland have comprised a significant source of information on climate, solar activity and geomagnetic field intensity over the past 800 000 years. There is, however, a large variability in the available <span class="hlt">10</span><span class="hlt">Be</span> records in terms of resolution and time coverage. We here present a comprehensive summary of results that have been put forward since the 1960s. Marine sediment was the first type of natural archive in which <span class="hlt">10</span><span class="hlt">Be</span> was detected (Arnold, 1956), and a decade later McCorkell et al. (1967) pioneered the ice archive field by counting <span class="hlt">10</span><span class="hlt">Be</span> beta activity in samples from Camp Century, Greenland. The method demands a large amount of material; in this case 1.2×106 litres of water were used. Using accelerator mass spectrometry, AMS, Raisbeck et al. (1978) undertook the second study of <span class="hlt">10</span><span class="hlt">Be</span> in polar ice, measuring <span class="hlt">10</span><span class="hlt">Be</span> concentrations in ice from Dome C, Antarctica. The AMS technique is exclusively used today for measurements of <span class="hlt">10</span><span class="hlt">Be</span> in small ice volumes (</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17904707','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17904707"><span id="translatedtitle">A preliminary study on the use of (<span class="hlt">10</span>)<span class="hlt">Be</span> in forensic radioecology of nuclear explosion sites.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Whitehead, N E; Endo, S; Tanaka, K; Takatsuji, T; Hoshi, M; Fukutani, S; Ditchburn, R G; Zondervan, A</p> <p>2008-02-01</p> <p>Cosmogenic (<span class="hlt">10</span>)<span class="hlt">Be</span>, known for use in dating studies, unexpectedly is also produced in nuclear explosions with an atom yield almost comparable to (e.g.) (137)Cs. There are major production routes via (13)C(n, alpha)(<span class="hlt">10</span>)<span class="hlt">Be</span>, from carbon dioxide in the air and the organic explosives, possibly from other bomb components and to a minor extent from the direct fission reaction. Although the detailed bomb components are speculative, carbon was certainly present in the explosives and an order of magnitude calculation is possible. The (n, alpha) cross-section was determined by irradiating graphite in a nuclear reactor, and the resulting (<span class="hlt">10</span>)<span class="hlt">Be</span> estimated by Accelerator Mass Spectrometry (AMS) giving a cross-section of 34.5+/-0.7mb (6-9.3MeV), within error of previous work. (<span class="hlt">10</span>)<span class="hlt">Be</span> should have applications in forensic radioecology. Historical environmental samples from Hiroshima, and Semipalatinsk (Kazakhstan) showed two to threefold (<span class="hlt">10</span>)<span class="hlt">Be</span> excesses compared with the background cosmogenic levels. A sample from Lake Chagan (a Soviet nuclear cratering experiment) contained more (<span class="hlt">10</span>)<span class="hlt">Be</span> than previously reported soils. (<span class="hlt">10</span>)<span class="hlt">Be</span> may be useful for measuring the fast neutron dose near the Hiroshima bomb hypocenter at neutron energies double those previously available. PMID:17904707</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMPP23B1838B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMPP23B1838B"><span id="translatedtitle">Geomagnetic field intensity and quantitative paleorainfall reconstruction from Chinese loess using <span class="hlt">10</span><span class="hlt">Be</span> and magnetic susceptibility</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beck, W.; zhou, W.; Li, C.; Wu, Z.; White, L.; Xian, F.</p> <p>2011-12-01</p> <p>7Be is produced in the atmosphere by cosmic ray spallation reactions and carried to the ground attached to aerosols, usually encapsulated in rain or snow. Numerous studies have shown that its flux to the ground is proportional to rainfall amount. Unfortunately, with a half life of only a few weeks, this observation has little relevance for reconstruction past rainfall amounts in paleosoils. Fortunately, 7Be has a long-lived sister isotope (<span class="hlt">10</span><span class="hlt">Be</span>) with a half life of ~1.5 Ma which can be used for such purposes. There are a number of complications, however. First, <span class="hlt">10</span><span class="hlt">Be</span> atmospheric production rate changes when the geomagnetic field intensity changes. Secondly, <span class="hlt">10</span><span class="hlt">Be</span> half life is long enough that <span class="hlt">10</span><span class="hlt">Be</span> which fell to the ground attached to dust some time in the past can become resuspended, meaning that there are two sources of <span class="hlt">10</span><span class="hlt">Be</span>, one meteoric, and the other recycled aeolian dust. Fortunately, we have found a method to deconvolute this knotty situation and have applied it to soils of the Chinese Loess Plateau, allowing us to reconstruct records of both geomagnetic field intensity and paleorainfall. To do so, we use the additional parameters magnetic susceptibility and coercivity to help define the inherited amount of each component, and to define what fraction of the variations in <span class="hlt">10</span><span class="hlt">Be</span> are associated with magnetic field fluctuations, versus that linked to rainfall variations. We also use a sediment age/depth model to convert <span class="hlt">10</span><span class="hlt">Be</span> concentration to <span class="hlt">10</span><span class="hlt">Be</span> flux, and finally, we use the modern 7Be vs. rainfall relationship and <span class="hlt">10</span><span class="hlt">Be</span>/7Be atmospheric production rate ratio to calculate quantitative paleorainfall rates. We have used these techniques to generate several such records ranging from the Holocene to MIS13 (Circa 525 ka BP), and will compare some of these to U-series dated speleothem records of δ18O.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvC..94b4326K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvC..94b4326K"><span id="translatedtitle">Monopole transitions to cluster states in <span class="hlt">10</span><span class="hlt">Be</span> and 9Li</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kanada-En'yo, Yoshiko</p> <p>2016-08-01</p> <p>Isoscalar monopole transitions from the ground states to cluster states in <span class="hlt">10</span><span class="hlt">Be</span> and 9Li are investigated using 6He+ α and 6He+ t cluster models, respectively. In <span class="hlt">10</span><span class="hlt">Be</span>, significant monopole strengths are obtained for 6He+ α cluster resonances of <span class="hlt">10</span><span class="hlt">Be</span>(03,4 +) above the α -decay threshold, whereas the strengths for 6He+ t cluster resonances in 9Li are not enhanced because of the large fragmentation of strengths in the corresponding energy region. The monopole transition to <span class="hlt">10</span><span class="hlt">Be</span>(02+) with the molecular orbital structure is relatively weak compared with those to 6He+ α cluster resonances. Monopole strength distributions do not directly correspond to distributions of 6He(0+)+ α and 6He(0+)+ t components but reflect the component of the deformed 6He cluster with a specific orientation, which is originally embedded in the ground state.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70013108','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70013108"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> analysis of a Quaternary weathering profile in the Virginia Piedmont.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Pavich, M.J.; Brown, Louis; Valette-Silver, J. Nathalie; Klein, Jeffrey; Middleton, Roy</p> <p>1985-01-01</p> <p>Samples from a residual weathering profile in the Virginia Piedmont have been analyzed for cosmogenic <span class="hlt">10</span><span class="hlt">Be</span>. Concentrations are highest in clay-rich soil and decrease exponentially to a depth of about 15 m. Despite uncertainties about the processes by which <span class="hlt">10</span><span class="hlt">Be</span> may be intercepted before entering the solum and eroded after incorporation, a minimum age may be calculated for the regolith. This calculation is based on the delivery rate of <span class="hlt">10</span><span class="hlt">Be</span> and its decay rate and suggests that this residual profile developed during a period no shorter than 8 × 105 yr. The calculated minimum age may be within a factor of 2 of maximum-age estimates based on surface lowering by erosion and on the rate of rock weathering to saprolite. The vertical distribution of <span class="hlt">10</span><span class="hlt">Be</span> in the profile could result from a steady-state balance of deposition, weathering, radioactive decay, and erosion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMEP51D..03V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMEP51D..03V"><span id="translatedtitle">River fluxes to the sea from the ocean's <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>von Blanckenburg, F.; Bouchez, J.</p> <p>2013-12-01</p> <p>The ratio of the meteoric cosmogenic radionuclide <span class="hlt">10</span><span class="hlt">Be</span> to the stable isotope 9Be is proposed here to be a flux proxy of terrigenous input into the oceans. The ocean's dissolved <span class="hlt">10</span><span class="hlt">Be</span>/9Be is set by (1) the flux of meteoric <span class="hlt">10</span><span class="hlt">Be</span> produced in the atmosphere; (2) the denudational flux of the rivers discharging into a given ocean basin; (3) the fraction of 9Be that is released from primary minerals during weathering (meaning the 9Be transported by rivers in either the dissolved form or adsorbed onto sedimentary particles and incorporated into secondary oxides); and (4) the fraction of riverine <span class="hlt">10</span><span class="hlt">Be</span> and 9Be actually released into seawater. Using published <span class="hlt">10</span><span class="hlt">Be</span>/9Be data of rivers for which independent denudation rate estimates exist we first find that the global average fraction of 9Be released during weathering into river waters and their particulate load is 20% and does not depend on denudation rate. We then evaluate this quantitative denudation rate proxy by using published dissolved seawater Be isotope data and a compilation of global river loads (15Gt/yr). We find that the measured global average oceanic dissolved <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio of about 0.9E-7 is satisfied by the mass balance if only 6.5% of the dissolved and reactive riverine Be is eventually released to the open ocean by boundary exchange. Except for the South Atlantic and the South Pacific, in which the <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio is dominated by Be advected through ocean circulation, good agreement results between <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios predicted by denudation rates and measured ocean <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios when we establish this mass balance for individual ocean basins. As the seawater <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio is faithfully recorded in marine chemical precipitates the <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio extracted from authigenic sediments can now serve to estimate relative changes in terrigenous input into the oceans back through time on a global and on a basin scale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014E%26PSL.387...34V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014E%26PSL.387...34V"><span id="translatedtitle">River fluxes to the sea from the oceanʼs <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>von Blanckenburg, Friedhelm; Bouchez, Julien</p> <p>2014-02-01</p> <p>The ratio of the meteoric cosmogenic radionuclide <span class="hlt">10</span><span class="hlt">Be</span> to the stable isotope 9Be is proposed here to be a flux proxy of terrigenous input into the oceans. The ocean's dissolved <span class="hlt">10</span><span class="hlt">Be</span>/9Be is set by (1) the flux of meteoric <span class="hlt">10</span><span class="hlt">Be</span> produced in the atmosphere; (2) the denudational flux of the rivers discharging into a given ocean basin; (3) the fraction of 9Be that is released from primary minerals during weathering (meaning the 9Be transported by rivers in either the dissolved form or adsorbed onto sedimentary particles and incorporated into secondary oxides); and (4) the fraction of riverine <span class="hlt">10</span><span class="hlt">Be</span> and 9Be actually released into seawater. Using published <span class="hlt">10</span><span class="hlt">Be</span>/9Be data of rivers for which independent denudation rate estimates exist we first find that the global average fraction of 9Be released during weathering into river waters and their particulate load is 20% and does not depend on denudation rate. We then evaluate this quantitative proxy for terrigenous inputs by using published dissolved seawater Be isotope data and a compilation of global river loads. We find that the measured global average oceanic dissolved <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio of about 0.9×10-7 is satisfied by the mass balance if only about 6% of the dissolved and adsorbed riverine Be is eventually released to the open ocean after escaping the coastal zone. When we establish this mass balance for individual ocean basins good agreement results between <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios predicted from known river basin denudation rates and measured ocean <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios. Only in the South Atlantic and the South Pacific the <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio is dominated by advected Be and in these basins the ratio is a proxy for ocean circulation. As the seawater <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio is faithfully recorded in marine chemical precipitates the <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio extracted from authigenic sediments can now serve to estimate relative changes in terrigenous input into the oceans back through time on a global and on an ocean basin scale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012E%26PSL.351..295V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012E%26PSL.351..295V"><span id="translatedtitle">Earth surface erosion and weathering from the <span class="hlt">10</span><span class="hlt">Be</span> (meteoric)/9Be ratio</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>von Blanckenburg, Friedhelm; Bouchez, Julien; Wittmann, Hella</p> <p>2012-10-01</p> <p>The isotope ratio of the meteoric cosmogenic nuclide <span class="hlt">10</span><span class="hlt">Be</span> to the mineral-derived stable isotope 9Be discloses both the Earth surface denudation rate and its weathering intensity. We develop a set of steady state mass balance equations that describes this system from a soil column over the hillslope scale to an entire river basin. The prerequisites making this new approach possible are: (1) the 9Be concentration of parent rock (typically 2.5±0.5 ppm in granitic and clastic sedimentary lithologies) is known; (2) both Be isotopes equilibrate between the fluids decomposing rock and reactive solids formed during weathering; and (3) a critical spatial scale is exceeded at which the fluxes of both isotopes into and out of the weathering zone are at steady state over the time scale of weathering (typically ˜10 kyr). For these cases the isotope ratios can be determined in bulk sediment or soil, on leachates from the reactive (adsorbed and pedogenic mineral-bound) phase in sediment or soil, and even on the dissolved phase in river water. The <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio offers substantial advantages over the single-isotope system of meteoric <span class="hlt">10</span><span class="hlt">Be</span>. The latter system allows to directly determine erosion rates only in the case that <span class="hlt">10</span><span class="hlt">Be</span> is fully retentive in the weathering zone and that riverine sorting has not introduced grain size-dependent <span class="hlt">10</span><span class="hlt">Be</span> concentration gradients in sediments. We show the feasibility of the <span class="hlt">10</span><span class="hlt">Be</span>/9Be tracer approach at the river scale for sediment and water samples in the Amazon basin, where independent estimates of denudation rates from in situ-produced <span class="hlt">10</span><span class="hlt">Be</span> exist. We furthermore calculate meaningful denudation rates from a set of published <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios measured in the dissolved load of globally distributed rivers. We conclude that this isotope ratio can be used to reconstruct global paleo-denudation from sedimentary records.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21322839','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21322839"><span id="translatedtitle">Analysis of T = 1 {sup 10}B States Analogue to {sup <span class="hlt">10</span>}<span class="hlt">Be</span> Cluster States</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Uroic, M.; Miljanic, D.; Blagus, S.; Bogovac, M.; Prepolec, L.; Skukan, N.; Soic, N.; Majer, M.; Milin, M.; Lattuada, M.; Musumarra, A.; Acosta, L.</p> <p>2009-08-26</p> <p>Current status of the search for T = 1 cluster states in {sup <span class="hlt">10</span>}<span class="hlt">Be</span>, {sup 10}B and {sup 10}C is presented. The best known of the three, {sup <span class="hlt">10</span>}<span class="hlt">Be</span>, has an established rotational band (6.18, 7.54 and 10.15 MeV) with unusually large moment of inertia. Search of their isobaric analogue in {sup 10}B is presented, with emphasis on {sup 3}He+{sup 11}B reaction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010GeoRL..3719403R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010GeoRL..3719403R"><span id="translatedtitle">Calibrating a long-term meteoric <span class="hlt">10</span><span class="hlt">Be</span> accumulation rate in soil</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reusser, Lucas; Graly, Joseph; Bierman, Paul; Rood, Dylan</p> <p>2010-10-01</p> <p>Using 13 samples collected from a 4.1 meter profile in a well-dated and stable New Zealand fluvial terrace, we present the first long-term accumulation rate for meteoric <span class="hlt">10</span><span class="hlt">Be</span> in soil (1.68 to 1.72 × 106 at/(cm2·yr)) integrated over the past ˜18 ka. Site-specific accumulation data, such as these, are prerequisite to the application of meteoric <span class="hlt">10</span><span class="hlt">Be</span> in surface process studies. Our data begin the process of calibrating long-term meteoric <span class="hlt">10</span><span class="hlt">Be</span> delivery rates across latitude and precipitation gradients. Our integrated rate is lower than contemporary meteoric <span class="hlt">10</span><span class="hlt">Be</span> fluxes measured in New Zealand rainfall, suggesting that long-term average precipitation, dust flux, or both, at this site were less than modern values. With accurately calibrated long-term delivery rates, such as this, meteoric <span class="hlt">10</span><span class="hlt">Be</span> will be a powerful tool for studying rates of landscape change in environments where other cosmogenic nuclides, such as in situ <span class="hlt">10</span><span class="hlt">Be</span>, cannot be used.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.9409G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.9409G"><span id="translatedtitle">Long-term cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> catchment-wide erosion rates in the Kruger National Park</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Glotzbach, Christoph; Paape, Alexander; Reinwarth, Bastian; Baade, Jussi; Miller, Jordan; Rowntree, Kate</p> <p>2015-04-01</p> <p>In this study we estimated long-term catchment-wide erosion rates in the central and southern Kruger National Park with cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> analyses. Samples were collected in small catchments (2-100 km2) upstream of dams, which were used to determine short-term sediment yield rates. <span class="hlt">10</span><span class="hlt">Be</span>-derived erosion rates vary from 4-15 mm/kyr. Although there are significant site-specific differences in geomorphic parameters and precipitation we could not identify a single parameter controlling long-term erosion. Geomorphic fieldwork reveals that an unknown fraction of sampled sand-sized channel sediments derived from partly extensive and up to a few-meters deep gully erosion, which may lead to an overestimation of <span class="hlt">10</span><span class="hlt">Be</span>-derived erosion rates. Cosmogenic nuclide production is rapidly decreasing with depth and consequently the measured <span class="hlt">10</span><span class="hlt">Be</span> concentration of stream sediments is a mixture of (i) sand with high <span class="hlt">10</span><span class="hlt">Be</span> concentration from colluvial creep or sheet flow from hillslopes and (ii) sand with low <span class="hlt">10</span><span class="hlt">Be</span> concentration from gully erosion. To correct erosion rates, we quantify sediments derived from gullies using a combination of mapping gullies using remote sensing data and field work and geochemical characterisation of intact hillslopes and gully side walls.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NIMPB.361..335B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..335B"><span id="translatedtitle">Preparation of ASTER in-house <span class="hlt">10</span><span class="hlt">Be</span>/9Be standard solutions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Braucher, R.; Guillou, V.; Bourlès, D. L.; Arnold, M.; Aumaître, G.; Keddadouche, K.; Nottoli, E.</p> <p>2015-10-01</p> <p>Since its commissioning in 2006, the commercially available certificated National Institute of Standards and Technology standard reference material NIST SRM 4325 is used at the French national facility ASTER (CEREGE, Aix-en-Provence) to normalize <span class="hlt">10</span><span class="hlt">Be</span> measurements. This standard solution being no longer disposable, we thus decided to produce in-house standards. As a first attempt, a STD-12 standard (<span class="hlt">10</span><span class="hlt">Be</span>/9Be = (4.939 ± 0.053) × 10-12) has been prepared from 2.5 kg of marine sediments with an adapted chemical protocol. Then, a <span class="hlt">10</span><span class="hlt">Be</span> enriched solution of known concentration being available, a STD-11 standard (<span class="hlt">10</span><span class="hlt">Be</span>/9Be = (1.191 ± 0.013) × 10-11) that will be used at ASTER in the near future to calibrate <span class="hlt">10</span><span class="hlt">Be</span> measurements and its dilution to the 10-14 level (STD-14 (<span class="hlt">10</span><span class="hlt">Be</span>/9Be = (5.468 ± 0.064) × 10-14)) have been prepared from it.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1815182C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1815182C"><span id="translatedtitle">Be2D: A model to understand the distribution of meteoric <span class="hlt">10</span><span class="hlt">Be</span> in soilscapes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Campforts, Benjamin; Vanacker, Veerle; Vanderborght, Jan; Govers, Gerard</p> <p>2016-04-01</p> <p>Cosmogenic nuclides have revolutionised our understanding of earth surface process rates. They have become one of the standard tools to quantify soil production by weathering, soil redistribution and erosion. Especially Beryllium-10 has gained much attention due to its long half-live and propensity to be relatively conservative in the landscape. The latter makes <span class="hlt">10</span><span class="hlt">Be</span> an excellent tool to assess denudation rates over the last 1000 to 100 × 103 years, bridging the anthropogenic and geological time scale. Nevertheless, the mobility of meteoric <span class="hlt">10</span><span class="hlt">Be</span> in soil systems makes translation of meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories into erosion and deposition rates difficult. Here we present a coupled soil hillslope model, Be2D, that is applied to synthetic and real topography to address the following three research questions. (i) What is the influence of vertical meteoric Be10 mobility, caused by chemical mobility, clay translocation and bioturbation, on its lateral redistribution over the soilscape, (ii) How does vertical mobility influence erosion rates and soil residence times inferred from meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories and (iii) To what extent can a tracer with a half-life of 1.36 Myr be used to distinguish between natural and human-disturbed soil redistribution rates? The model architecture of Be2D is designed to answer these research questions. Be2D is a dynamic model including physical processes such as soil formation, physical weathering, clay migration, bioturbation, creep, overland flow and tillage erosion. Pathways of meteoric <span class="hlt">10</span><span class="hlt">Be</span> mobility are simulated using a two step approach which is updated each timestep. First, advective and diffusive mobility of meteoric <span class="hlt">10</span><span class="hlt">Be</span> is simulated within the soil profile and second, lateral redistribution because of lateral soil fluxes is calculated. The performance and functionality of the model is demonstrated through a number of synthetic and real model runs using existing datasets of meteoric <span class="hlt">10</span><span class="hlt">Be</span> from case-studies in southeastern US. Brute</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JGRF..114.4020J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JGRF..114.4020J"><span id="translatedtitle">Tracing hillslope sediment production and transport with in situ and meteoric <span class="hlt">10</span><span class="hlt">Be</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jungers, Matthew C.; Bierman, Paul R.; Matmon, Ari; Nichols, Kyle; Larsen, Jennifer; Finkel, Robert</p> <p>2009-12-01</p> <p>We use in situ-produced and meteoric <span class="hlt">10</span><span class="hlt">Be</span>, analyzed in soils from 28 pits on four hillcrest-parallel transects along a 14° hillslope in the Great Smoky Mountains, North Carolina, as tracers of soil production and transport. We rely upon amalgamation both to investigate and smooth spatial variability in <span class="hlt">10</span><span class="hlt">Be</span> concentrations. Lidar indicates that the hillslope is topographically complex and that soil is moved downslope diffusively until it encounters the ephemeral channel network and is rapidly exported. In situ-produced <span class="hlt">10</span><span class="hlt">Be</span>, measured in depth profiles, indicates that over millennial timescales, soils are mixed above the soil-saprolite boundary. In contrast, meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations increase with depth and are correlated to concurrent increases of dithionite-extractable Al and pH, observations explained by similar Al and Be mobility in the soil. The concentrations of both meteoric and in situ-produced <span class="hlt">10</span><span class="hlt">Be</span> increase downslope proportional to the maximum soil particle path length. The data suggest virtual downslope soil velocities of 1.1-1.7 cm yr-1 in a well-mixed active transport layer ˜60 cm thick. The thickness of this transport layer is constant downslope and depends on the rooting depth and consequent root wad thickness of downed trees on the slope, both of which reflect depth to the soil/saprolite boundary. Both meteoric and in situ-produced <span class="hlt">10</span><span class="hlt">Be</span> suggest that soil production is balanced by surface denudation at rates between 10 and 13 m Myr-1. Soil residence times on the slope range from 21 to 33 kyr based on the meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories. Major element geochemical analysis suggests little if any elemental loss during soil transport downslope.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015QSRv..126..140B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015QSRv..126..140B"><span id="translatedtitle">Cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages reveal a 9.3 ka BP glacier advance and the Late Weichselian-Early Holocene glacial history of the Drangajökull region, northwest Iceland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brynjólfsson, Skafti; Schomacker, Anders; Ingólfsson, Ólafur; Keiding, Jakob K.</p> <p>2015-10-01</p> <p>We present twenty-four new cosmogenic isotope (<span class="hlt">36</span><span class="hlt">Cl</span>) surface exposure ages from erratic boulders, moraine boulders and glacially eroded bedrock that constrain the late Weichselian to Holocene glacial history of the Drangajökull region, northwest Iceland. The results suggest a topographically controlled ice sheet over the Vestfirðir (Westfjords) peninsula during the last glaciation. Cold based non-erosive sectors of the ice sheet covered most of the mountains while fjords and valleys were occupied with erosive, warm-based ice. Old<span class="hlt">36</span><span class="hlt">Cl</span> exposure ages from highlands and mountain plateaux (L8; 76.5 ka and H1; 41.6 ka) in combination with younger erratic boulders (L7; 26.2 and K1-K4; 15.0-13.8 ka) superimposed on such surfaces suggest the presence of non-erosive ice over uplands and plateaux in the Vestfirðir peninsula during the last glaciation. Glacially scoured terrain and erratic boulders yielding younger exposure ages (L1-L6; 11.3-9.1 ka and R1, R6-R7; 10.6-9.4 ka) in the lowland areas indicate that the valleys and fjords of the Vestfirðir peninsula were occupied by warm-based, dynamic ice during the last glaciation. The deglaciation of mountain Leirufjall by 26.2 ka BP suggests that ice thinning and deglaciation of some mountains and plateaux preceded any significant lateral retreat of the ice sheet. Subsequently this initial ice thinning was followed by break-up of the shelf based ice sheet off Vestfirðir about 15 ka BP. Hence, the new exposure ages suggest a stepwise asynchronous deglaciation on land, following the shelf break-up with some valleys and most of the highlands, ice free by 14-15 ka BP. The outermost moraine at the mouth of Leirufjörður is dated to 9.3 ka BP, and we suggest the moraine to be formed by a glacier re-advance in response to a cooler climate forced by the reduced Atlantic Meridional Overturning Circulation at around 9.3 ka BP. A system of moraines proximal to the 9.3 ka moraine in Leirufjörður as well as a 9.4 ka deglaciation age</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006AGUFM.H21H..06B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006AGUFM.H21H..06B&link_type=ABSTRACT"><span id="translatedtitle">Using the <span class="hlt">10</span>-<span class="hlt">Be</span> Grain Size Dependency in Alluvial Sediments to Investigate Hillslope and Channel Processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Belmont, P.; Pazzaglia, F. J.; Gosse, J.</p> <p>2006-12-01</p> <p>The method for estimating basin-wide erosion rates from in situ produced <span class="hlt">10</span>-<span class="hlt">Be</span> in alluvial sediments has matured over the past decade; nevertheless, several applications have not been fully explored. Foremost among these is identifying hillslope weathering and erosion processes through a study of the cosmogenic inventories of specific grain-size fractions of alluvial sediment. We applied a nested sampling strategy to two (6-12 km 2) basins on the Olympic Peninsula, western Washington State, to investigate how cosmogenic nuclides are sequestered across different alluvial grain sizes. Alluvium was sampled near the mouth and headwaters of each basin. The <span class="hlt">10</span>-<span class="hlt">Be</span> concentration in river-borne quartz was measured for two grain-size fractions, medium-sized sand (0.25 - 0.50 mm) and an amalgamation of 80+ cobbles (22.6 - 90 mm). Extensive granulometry was conducted at each site and several different methods were used to qualify weathering intensity of channel boulders, which differs substantially for the two basins. We observed different concentrations of <span class="hlt">10</span>-<span class="hlt">Be</span> in all eight grain size fractions. At both headwater sites the cobbles consistently exhibit 25% lower <span class="hlt">10</span>-<span class="hlt">Be</span> concentrations, compared to sand. In contrast, the cobbles in the downstream sites differed with one basin exhibiting 22% higher <span class="hlt">10</span>-<span class="hlt">Be</span> concentration compared to sand and the other site exhibiting 55% lower <span class="hlt">10</span>-<span class="hlt">Be</span> concentration in the cobbles, compared to sand. A GIS was used to extract basin morphological metrics including basin hypsometry, hillslope gradient and channel gradient. Concentrations of <span class="hlt">10</span>-<span class="hlt">Be</span> at the headwater sites are best explained by shielding of the coarser grain size fraction and its delivery to the channel by deep-seated landslide processes. The contrasting grain-size dependency at the two downstream sites requires a more complex interplay between hillslope and channel processes including cobble weathering and grain size reduction during fluvial transport. Although preliminary, these results</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMEP52D..06O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMEP52D..06O"><span id="translatedtitle">Unexpected Delivery of Meteoric <span class="hlt">10</span><span class="hlt">Be</span> to Critical Zone Soils, Front Range, Colorado</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ouimet, W. B.; Dethier, D. P.; Bierman, P. R.; Wyshnytsky, C.; Rood, D. H.</p> <p>2011-12-01</p> <p>Using meteoric <span class="hlt">10</span><span class="hlt">Be</span> in geomorphic studies requires knowing its long-term delivery rate to the earth surface. Delivery rates vary by latitude due to the influence of geomagnetic field intensity and solar activity and locally due to differences in precipitation and rates of dustfall accumulation, which are responsible for depositing primary and recycled meteoric <span class="hlt">10</span><span class="hlt">Be</span> to geomorphic surfaces, respectively. Because influences on delivery rate vary in space and time, recent studies emphasize the use of inventory sites where the total concentration of meteoric <span class="hlt">10</span><span class="hlt">Be</span> is measured on stable landforms of known age to determine site-specific, long-term delivery rates. To date, measured long-term delivery rates typically have fallen within the range of expected rates for the site's latitude and modern annual rate of precipitation, including minor contributions of dust to the total inventory of meteoric <span class="hlt">10</span><span class="hlt">Be</span>. Here, we present the results of a meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventory measured on a Pinedale (~15 ka) moraine within the Boulder Creek Critical Zone Observatory, Front Range, Colorado. We report a long-term delivery rate of meteoric <span class="hlt">10</span><span class="hlt">Be</span> for this site of 4.2 to 4.6 × 106 atoms/cm2/yr, significantly higher than the expected delivery rate (1 to 1.3 × 106 atoms/cm2/yr) for it's latitude (40 degrees) and annual precipitation rate (85-95 cm/yr). A detailed analysis of soils in the Front Range (of various age) indicate that long-term dust accumulation rates are less than ~0.1 grams/cm2/kyr and therefore do not significantly influence the total amount of meteoric <span class="hlt">10</span><span class="hlt">Be</span> delivered to geomorphic surfaces. When applied to measured concentrations of meteoric <span class="hlt">10</span><span class="hlt">Be</span> in soils within the Gordon Gulch CZO catchment, our high, inventory-based delivery rate suggests that hillslopes are 10 to 40 ka younger (all post-LGM) than suggested by published precipitation based delivery rates. Furthermore, this result, combined with a long-term delivery rate calibrated nearby on the High Plains (1200 m lower in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.6069W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.6069W"><span id="translatedtitle">Reactive and dissolved meteoric <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios in the Amazon basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wittmann, Hella; Dannhaus, Nadine; von Blanckenburg, Friedhelm; Bouchez, Julien; Suessenberger, Annette; Guyot, Jean-Loup; Maurice, Laurence; Filizola, Naziano; Gaillardet, Jerome; Christl, Marcus</p> <p>2014-05-01</p> <p>Recently, the ratio of the meteoric cosmogenic nuclide <span class="hlt">10</span><span class="hlt">Be</span> to stable 9Be has been established as a weathering and erosion proxy where meteoric <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios in reactive phases of secondary weathering products leached from detrital Amazonian river sediment were measured[1]. For this dataset, we derived a new <span class="hlt">10</span><span class="hlt">Be</span>-based mass balance, which compares the fluxes exported during erosion and weathering, Fout, calculated by the sum of [<span class="hlt">10</span><span class="hlt">Be</span>]reac multiplied by gauging-derived sediment discharge and [<span class="hlt">10</span><span class="hlt">Be</span>]dissmultiplied by water discharge, to the meteoric depositional flux Fin. This assessment allows evaluating the weathering state of the Amazon basin. Further, in order to assess equilibration of reactive phases in the water column, we measured (<span class="hlt">10</span><span class="hlt">Be</span>/9Be)reac ratios leached from suspended sediments for two depth profiles of the Amazon (55m depth) and Madeira (12m depth) Rivers, their corresponding surface dissolved <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios, as well as dissolved ratios of smaller Amazon tributaries (Beni, Madre de Dios) to compare with published reactive ratios[1]. In these rivers, modest pH and salinity fluctuations help to constrain a 'simple' system that might however still be affected by seasonally changing isotopic compositions between water and suspended sediment[2] and seasonal fluctuations of TSS and TDS[3]. The <span class="hlt">10</span><span class="hlt">Be</span>-based mass balance shows that in Andean source areas Fout/Fin ≡1, indicating a balance between ingoing and exported flux, whereas in the Shield headwaters, Fout/Fin=0.3, indicating a combination of decay of <span class="hlt">10</span><span class="hlt">Be</span> during storage and little export of <span class="hlt">10</span><span class="hlt">Be</span> associated with particulate and dissolved loads. In central Amazonia, the export of <span class="hlt">10</span><span class="hlt">Be</span> decreases slightly relative to its atmospheric flux as evidenced by Fout/Fin=0.8 for the Amazon and Madeira Rivers. This value is interpreted as being close to steady state, but its modification could be due to additions of Shield-derived sediment to sediment carried in the main river[4]. Regarding the depth profiles, our</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013NIMPB.294...72H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NIMPB.294...72H"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> measurements at MALT using reduced-size samples of bulk sediments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Horiuchi, Kazuho; Oniyanagi, Itsumi; Wasada, Hiroshi; Matsuzaki, Hiroyuki</p> <p>2013-01-01</p> <p>In order to establish <span class="hlt">10</span><span class="hlt">Be</span> measurements on reduced-size (1-10 mg) samples of bulk sediments, we investigated four different pretreatment designs using lacustrine and marginal-sea sediments and the AMS system of the Micro Analysis Laboratory, Tandem accelerator (MALT) at The University of Tokyo. The <span class="hlt">10</span><span class="hlt">Be</span> concentrations obtained from the samples of 1-10 mg agreed within a precision of 3-5% with the values previously determined using corresponding ordinary-size (∼200 mg) samples and the same AMS system. This fact demonstrates reliable determinations of <span class="hlt">10</span><span class="hlt">Be</span> with milligram levels of recent bulk sediments at MALT. On the other hand, a clear decline of the BeO- beam with tens of micrograms of 9Be carrier suggests that the combination of ten milligrams of sediments and a few hundred micrograms of the 9Be carrier is more convenient at this stage.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMEP43E..08V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMEP43E..08V"><span id="translatedtitle">Earth surface erosion and weathering from the <span class="hlt">10</span><span class="hlt">Be</span> (meteoric)/9Be ratio</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>von Blanckenburg, F.; Bouchez, J.; Wittmann, H.; Dannhaus, N.</p> <p>2012-12-01</p> <p>A perfect clock of the stability of the Earth surface is one that combines a first isotope the flux of which depends on the release rate during erosion, and a second isotope produced at constant rate. The ratio of the meteoric cosmogenic nuclide <span class="hlt">10</span><span class="hlt">Be</span> to stable 9Be is such a system. We provide a quantitative framework for its use. In a weathering zone some of the 9Be, present typically in 2.5ppm concentrations in silicate minerals, is released and partitioned between a reactive phase (adsorbed to clay and hydroxide surfaces, given the high partition coefficients at intermediate pH), and into the dissolved phase. The combined mass flux of both phases is defined by the soil formation rate and a mineral dissolution rate - and is hence proportional to the chemical weathering rate and the denudation rate. At the same time, the surface of the weathering zone is continuously exposed to fallout of meteoric <span class="hlt">10</span><span class="hlt">Be</span>. This <span class="hlt">10</span><span class="hlt">Be</span> percolates into the weathering zone where it mixes with dissolved 9Be. Both isotopes may exchange with the adsorbed Be, given that equilibration rate of Be is fast relative to soil residence times. Hence a <span class="hlt">10</span><span class="hlt">Be</span>/9Be(reactive) ratio results in soils from which the total denudation rate can be calculated. A prerequisite is that the flux of meteoric <span class="hlt">10</span><span class="hlt">Be</span> is known from field experiments or from global production models [1], that the 9Be concentration in bedrock (mostly 2.5ppm) is known [2], and that the reactive Be can be chemically extracted from soil or sediment [3]. In rivers, when reactive Be and dissolved Be equilibrate, a catchment-wide denudation rate can be determined from both sediment and a sample of filtered river water, where the sediment <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio is independent of grain size. We have tested this approach in sediment-bound Be and dissolved Be in water of the Amazon and Orinoco basin. The reactive Be was extracted from sediment by combined hydroxylamine and HCl leaches [2]. In the Amazon trunk stream, the Orinoco, Apure, and La Tigra river <span class="hlt">10</span><span class="hlt">Be</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014NatSR...4E6408S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014NatSR...4E6408S"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> climate fingerprints during the Eemian in the NEEM ice core, Greenland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sturevik-Storm, Anna; Aldahan, Ala; Possnert, Göran; Berggren, Ann-Marie; Muscheler, Raimund; Dahl-Jensen, Dorthe; Vinther, Bo M.; Usoskin, Ilya</p> <p>2014-09-01</p> <p>Several deep Greenland ice cores have been retrieved, however, capturing the Eemian period has been problematic due to stratigraphic disturbances in the ice. The new Greenland deep ice core from the NEEM site (77.45°N, 51.06°W, 2450 m.a.s.l) recovered a relatively complete Eemian record. Here we discuss the cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> isotope record from this core. The results show Eemian average <span class="hlt">10</span><span class="hlt">Be</span> concentrations about 0.7 times lower than in the Holocene which suggests a warmer climate and approximately 65-90% higher precipitation in Northern Greenland compared to today. Effects of shorter solar variations on <span class="hlt">10</span><span class="hlt">Be</span> concentration are smoothed out due to coarse time resolution, but occurrence of a solar maximum at 115.26-115.36 kyr BP is proposed. Relatively high <span class="hlt">10</span><span class="hlt">Be</span> concentrations are found in the basal ice sections of the core which may originate from the glacial-interglacial transition and relate to a geomagnetic excursion about 200 kyr BP.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70021881','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70021881"><span id="translatedtitle">Constraints on the sedimentation history of San Francisco Bay from 14C and <span class="hlt">10</span><span class="hlt">Be</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>VanGeen, A.; Valette-Silver, N. J.; Luoma, S.N.; Fuller, C.C.; Baskaran, M.; Tera, F.; Klein, J.</p> <p>1999-01-01</p> <p>Industrialization and urbanization around San Francisco Bay as well as mining and agriculture in the watersheds of the Sacramento and San Joaquin rivers have profoundly modified sedimentation patterns throughout the estuary. We provide some constraints on the onset of these erosional disturbances with <span class="hlt">10</span><span class="hlt">Be</span> data for three sediment cores: two from Richardson Bay, a small embayment near the mouth of San Francisco Bay, and one from San Pablo Bay, mid-way between the river delta and the mouth. Comparison of pre-disturbance sediment accumulation determined from three 14C-dated mollusk shells in one Richardson Bay core with more recent conditions determined from the distribution of 210Pb and 234Th [Fuller, C.C., van Geen, A., Baskaran, M, Anima, R.J., 1999. Sediment chronology in San Francisco Bay, California, defined by 210Pb, 234Th, 239,240Pu.] shows that the accumulation rate increased by an order of magnitude at this particular site. All three cores from San Francisco Bay show subsurface maxima in <span class="hlt">10</span><span class="hlt">Be</span> concentrations ranging in magnitude from 170 to 520 x 106 atoms/g. The transient nature of the increased <span class="hlt">10</span><span class="hlt">Be</span> input suggests that deforestation and agricultural develop- ment caused basin-wide erosion of surface soils enriched in <span class="hlt">10</span><span class="hlt">Be</span>. probably before the turn of the century.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4179124','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4179124"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> climate fingerprints during the Eemian in the NEEM ice core, Greenland</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sturevik-Storm, Anna; Aldahan, Ala; Possnert, Göran; Berggren, Ann-Marie; Muscheler, Raimund; Dahl-Jensen, Dorthe; Vinther, Bo M.; Usoskin, Ilya</p> <p>2014-01-01</p> <p>Several deep Greenland ice cores have been retrieved, however, capturing the Eemian period has been problematic due to stratigraphic disturbances in the ice. The new Greenland deep ice core from the NEEM site (77.45°N, 51.06°W, 2450 m.a.s.l) recovered a relatively complete Eemian record. Here we discuss the cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> isotope record from this core. The results show Eemian average <span class="hlt">10</span><span class="hlt">Be</span> concentrations about 0.7 times lower than in the Holocene which suggests a warmer climate and approximately 65–90% higher precipitation in Northern Greenland compared to today. Effects of shorter solar variations on <span class="hlt">10</span><span class="hlt">Be</span> concentration are smoothed out due to coarse time resolution, but occurrence of a solar maximum at 115.26–115.36 kyr BP is proposed. Relatively high <span class="hlt">10</span><span class="hlt">Be</span> concentrations are found in the basal ice sections of the core which may originate from the glacial-interglacial transition and relate to a geomagnetic excursion about 200 kyr BP. PMID:25266953</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21254838','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21254838"><span id="translatedtitle">Dilute Nuclear States: {sup 12}C, {sup <span class="hlt">10</span>}<span class="hlt">Be</span> and {sup 14}C</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Freer, M.</p> <p>2008-11-11</p> <p>The experimental evidence for dilute {alpha}-particle states in {sup 12}C, {sup <span class="hlt">10</span>}<span class="hlt">Be</span> and {sup 14}C is discussed. The question of the location of the 2{sup +} excitation of the 7.65 MeV {sup 12}C state remains unresolved, as does the existence of possible analogue states in {sup 14}C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1714837S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1714837S"><span id="translatedtitle">The drainage of the Baltic Ice Lake and a new Scandinavian reference <span class="hlt">10</span><span class="hlt">Be</span> production rate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stroeven, Arjen P.; Heyman, Jakob; Fabel, Derek; Björck, Svante; Caffee, Marc W.; Fredin, Ola; Harbor, Jonathan M.</p> <p>2015-04-01</p> <p>An important constraint on the reliability of cosmogenic nuclide exposure dating is the derivation of tightly controlled production rates. We present a new dataset for <span class="hlt">10</span><span class="hlt">Be</span> production rate calibration from Mount Billingen, southern Sweden, the site of the final drainage of the Baltic Ice Lake, an event dated to 11,620 ± 100 cal yr BP. Nine samples of flood-scoured bedrock surfaces and depositional boulders and cobbles unambiguously connected to the drainage event yield a reference <span class="hlt">10</span><span class="hlt">Be</span> production rate of 4.09 ± 0.22 atoms g-1 yr-1 for the CRONUS Lm scaling and 3.93 ± 0.21 atoms g-1 yr-1 for the LSD general spallation scaling. We also recalibrate the reference <span class="hlt">10</span><span class="hlt">Be</span> production rates for four sites in Norway and combine these with the Billingen results to derive a tightly clustered Scandinavian reference <span class="hlt">10</span><span class="hlt">Be</span> production rate of 4.12 ± 0.10 (4.12 ± 0.25 for altitude scaling) atoms g-1 yr-1 for the Lm scaling scheme and 3.96 ± 0.10 (3.96 ± 0.24 for altitude scaling) atoms g-1 yr-1 for the LSD scaling scheme.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1214299R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1214299R"><span id="translatedtitle">Using <span class="hlt">10</span><span class="hlt">Be</span> records to identify possible 14C calibration uncertainties during the Holocene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raimund, Muscheler</p> <p>2010-05-01</p> <p>The Intcal04 and Intcal09 radiocarbon calibration records are based on multiple tree-ring 14C data sets for Holocene period (Reimer et al. 2004, Reimer et al. 2009). While the dendrochronolgical dating of the trees is supposedly free of errors there are differences between various 14C data sets that underlie the 14C calibration curve. Due to lack of knowledge about the reasons for the differences the Intcal04/09 calibration curves provide a smoothed average of the underlying 14C records. Therefore, problems in one or several of the underlying 14C records would translate directly into errors in the 14C age calibration. Additional knowledge about expected variations in the 14C production rate could help to improve the calibration record since it would allow us to assess how well the different 14C records represent the atmospheric 14C concentration. I propose that <span class="hlt">10</span><span class="hlt">Be</span> records could be used as additional criteria to chose which of the published 14C records should be preferred (or given stronger weight) for the construction of the calibration curve. Alternatively, <span class="hlt">10</span><span class="hlt">Be</span> records could point to periods where 14C data should be re-measured in order to improve the calibration curve. I will show for some case studies that the <span class="hlt">10</span><span class="hlt">Be</span> records from the Greenland ice cores (Muscheler et al. 2004, Vonmoos et al. 2006) indeed provide useful information to scrutinise the Intcal04/09 calibration curve, which could help to improve the 14C calibration curve during the Holocene. Especially shorter-term changes are strongly dampened in the Intcal04/09 calibration record. However, <span class="hlt">10</span><span class="hlt">Be</span> and some 14C records do exhibit more variability as compared to the calibration record. Therefore, the combined <span class="hlt">10</span><span class="hlt">Be</span>/14C approach could add confidence that these should be reflected in the 14C calibration record. References: Muscheler, R., Beer, J. et al., 2004. Changes in the carbon cycle during the last deglaciation as indicated by the comparison of <span class="hlt">10</span><span class="hlt">Be</span> and 14C records. Earth and Planetary Science Letters</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000NIMPB.172..873B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000NIMPB.172..873B"><span id="translatedtitle">Determination of cosmogenic production rates of <span class="hlt">10</span><span class="hlt">Be</span>, 3He and 3H in water</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brown, Erik T.; Trull, Thomas W.; Jean-Baptiste, Philippe; Raisbeck, Grant; Bourlès, Didier; Yiou, Françoise; Marty, Bernard</p> <p>2000-10-01</p> <p>To improve our understanding of present-day cosmogenic production systematics of <span class="hlt">10</span><span class="hlt">Be</span>, 3H and 3He, we exposed three sets of targets of purified water at altitudes of 620, 3810 and 4745 m in the Mont Blanc Massif of the French Alps. In addition, tanks were stored 1780 m underground to quantify 3He contributions from decay of "inherited" tritium initially present in the water. After analyses of 3He and <span class="hlt">10</span><span class="hlt">Be</span>, both the summit and tunnel 3H- 3He tanks were re-degassed and stored underground for an additional year. The stored summit tanks were then analyzed to determine cosmogenic 3H levels by the 3He ingrowth method, and the tunnel tanks used to re-determine inherited tritium. Production rates (in atoms per g H 2O per year) for direct production of 3He and <span class="hlt">10</span><span class="hlt">Be</span> were 1824±52 and 112±9; 1013±16 and 70±5; and 134±58 and 5.9±0.7 at the three elevations, respectively. We determined production ratios of 0.32±0.08 for 3H: 3He and 20.2±1.5 for ( 3H+ 3He): <span class="hlt">10</span><span class="hlt">Be</span>. Our <span class="hlt">10</span><span class="hlt">Be</span> production rates, when normalized for inter-laboratory calibration and for differences in geomagnetic latitude of exposure, are somewhat lower than results of a similar experiment undertaken by Nishiizumi et al. (1996). Our 3H: 3He ratio is consistent with theoretical and meteorite estimates (Kruger and D. Heymann, 1968), but considerably lower than values assumed in many exposure age studies of igneous rocks (e.g., (Kurz, 1986; Trull et al., 1995)).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012E%26PSL.333..146L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012E%26PSL.333..146L"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span>-derived Himalayan denudation rates and sediment budgets in the Ganga basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lupker, Maarten; Blard, Pierre-Henri; Lavé, Jérôme; France-Lanord, Christian; Leanni, Laetitia; Puchol, Nicolas; Charreau, Julien; Bourlès, Didier</p> <p>2012-06-01</p> <p>The Himalayas represent the archetype of mountain building due to active continental collision and are considered in many studies as the locus of intense interactions between climate, denudation and tectonics. Estimates of modern denudation rates across the entire range remain, however, relatively sparse. In this study, in situ-produced cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> concentrations were measured in detritic quartz in order to determine basin-scale denudation rates for the central part of the Himalayan range. River sand was sampled over several years in the main trans-Himalayan rivers, from the Himalayan front to the Ganga outlet in Bangladesh. The calculated <span class="hlt">10</span><span class="hlt">Be</span> denudation rates of the trans-Himalayan river basins range from 0.5 to 2.4 mm yr-1 (average 1.3 mm yr-1) and vary by up to a factor of 3 between sampling years. These denudation rates strongly contrast with the 0.007 mm yr-1 denudation rate of southern tributary basins draining the Indian craton. This work also shows that in the Ganga basin, no systematic evolution of average <span class="hlt">10</span><span class="hlt">Be</span> concentrations is observed during floodplain transfer, implying that distal samples can be used to estimate the integrated denudation rate of the whole central Himalayan range. Samples from the Ganga in Bangladesh display remarkably low variability in <span class="hlt">10</span><span class="hlt">Be</span> concentration, implying an average Himalayan denudation rate of 1.0-1.1 mm yr-1. However, within the floodplain, several samples suggest a recent perturbation of sediment transport dynamics with a recent increase in the relative sediment contribution from southern tributaries. The Himalayan sediment flux, deduced from the <span class="hlt">10</span><span class="hlt">Be</span> denudation rate of the range, is 610±230 Mt yr-1. This flux is consistent, within uncertainty, with sediment fluxes derived from sediment gauging. The similarity of the two flux estimates suggests that Himalayan erosion fluxes have remained stable over the last centuries, even if the large uncertainties associated with each method hamper more precise assessments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRF..120.1626A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRF..120.1626A"><span id="translatedtitle">Particle trajectories on hillslopes: Implications for particle age and <span class="hlt">10</span><span class="hlt">Be</span> structure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Anderson, Robert S.</p> <p>2015-09-01</p> <p>Many geomorphic systems act as conveyor belts onto which material is loaded at a particular rate and is transported in one direction toward another system that serves as a sink. As the material travels, it ages, it changes in grain size, it accumulates cosmogenic radionuclides, it adsorbs or releases nutrients, and it weathers. Here I address the hillslope conveyor. As many geochemical processes are depth-dependent, the depth history of a particle becomes important to know. I calculate soil particle trajectories in the horizontal-depth plane and address three cases, one in which horizontal speeds decline exponentially with depth, a second in which they are uniform with depth, and a third in which horizontal speeds are also uniform but all profile values are vertically well-mixed. Vertical speeds are governed by continuity in an incompressible medium and by the boundary condition of zero vertical particle speed at the soil surface. Particle trajectories must therefore become surface parallel at the surface. Knowledge of soil particle trajectories allows calculation of residence times and concentration profiles of <span class="hlt">10</span><span class="hlt">Be</span> in the soil. The results inform strategies for interpretation of nuclide concentrations in soils and stream sediments and for inference of transport rate profiles. In all steady cases, the particle age and <span class="hlt">10</span><span class="hlt">Be</span> structure are uniform with distance from the divide. When significant vertical gradients in horizontal speed occur, the patterns of particle age and of <span class="hlt">10</span><span class="hlt">Be</span> concentration are dominated by the depth scale of the transport process. In unmixed cases, the particle age and <span class="hlt">10</span><span class="hlt">Be</span> concentration in near-surface samples can greatly exceed the vertically averaged values, reflecting the fact that the vertical speeds of particles slow dramatically as they near the surface. In cases in which horizontal speed varies significantly with depth, the vertically averaged concentration of <span class="hlt">10</span><span class="hlt">Be</span> within the soil can significantly underpredict the mean <span class="hlt">10</span><span class="hlt">Be</span> concentration</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..18.9351S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..18.9351S&link_type=ABSTRACT"><span id="translatedtitle">Headwall erosion rates from cosmogenic (<span class="hlt">10</span>) <span class="hlt">Be</span> in supraglacial debris, Chhota Shigri Glacier, Indian Himalaya</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scherler, Dirk; Egholm, David</p> <p>2016-04-01</p> <p>Debris-covered glaciers are widespread within the Himalaya and other steep mountain ranges. They testify to active erosion of ice-free bedrock hillslopes that tower above valley glaciers, sometimes more than 1 km high. It is long known that debris cover significantly reduces surface ablation rates and thereby influences glacial mass balances; but its dynamic evolution along with climatic and topographic changes is poorly studied. Better understanding the coupling of ice-free bedrock hillslopes and glaciers in steep mountains requires means to assess headwall erosion rates. Here, we present headwall erosion rates derived from <span class="hlt">10</span><span class="hlt">Be</span> concentrations in the ablation-dominated medial moraine of the Chhota Shigri Glacier, Indian Himalaya. We combine our empirical, field-based approach with a numerical model of headwall erosion and glacial debris transport to assess permissible patterns of headwall erosion on the ice-free bedrock hillslopes surrounding the Chhota Shigri Glacier. Our five samples, each separated by approximately 500 m along the glacier, consist of an amalgamation of >1000 surface clasts with grain sizes between ˜1 and ˜30 mm that were taken from the medial moraine. Our results show that <span class="hlt">10</span><span class="hlt">Be</span> concentrations increase downglacier from ˜3×104 to ˜6×104 atoms g‑1, yielding headwall erosion rates of ˜1.3-0.6 mm yr‑1. The accumulation of <span class="hlt">10</span><span class="hlt">Be</span> during debris residence on the ice surface can only account for a small fraction (<20%) of the downglacier increase. Other potential explanations include (1) heterogeneous source areas with differences average productions rates, and (2) homogeneous source areas but temporally variable headwall erosion rates. We use the <span class="hlt">10</span><span class="hlt">Be</span>-derived headwall erosion rates to define debris supply rates from ice-free bedrock hillslopes in the numerical ice model iSOSIA. Headwall debris that is deposited in the ablation zone of the ice surface becomes englacial, is passively advected with the ice and emerges in the ablation zone where</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMGC33B1017D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMGC33B1017D"><span id="translatedtitle">Synchronizing the North American Varve Chronology with Greenland ice core records using meteoric <span class="hlt">10</span><span class="hlt">Be</span> flux</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>DeJong, B.; Balco, G.; Ridge, J. C.; Rood, D. H.; Bierman, P. R.</p> <p>2012-12-01</p> <p>The North American Varve Chronology (NAVC) is a floating 5700-year sequence of glacial lake varves deposited in the Connecticut River Valley of the northeast US ~18,000-12,500 years ago. The NAVC is an annually resolved record of regional climate and ice-marginal processes at 40-45° N latitude, near the margin of the retreating Laurentide Ice Sheet (LIS). NAVC deposition occurred at the same time as rapid and abrupt Arctic and North Atlantic climate changes that took place during the last deglaciation. An age estimate for the NAVC based on radiocarbon dated plant macrofossils in individual varves implies a relationship between ice-marginal events recorded by the NAVC and climate events recorded in Greenland ice cores. For example, the retreat rate of the LIS up the Connecticut River Valley increased during the Bolling warming in Greenland, a readvance of the LIS margin took place during the Older Dryas cold period, and a correlation between an outburst flood from glacial Lake Iroquois and the Intra-Allerod Cold Period supports the hypothesis that the flood affected North Atlantic thermohaline circulation. On the other hand, a doubling of the ice-margin retreat rate recorded by the NAVC around 16,000 years ago coincides with a relatively cold period in Greenland. Our goal is to investigate the precise time relationship between these events by synchronizing the NAVC with the Greenland ice core time scale using atmospherically-produced <span class="hlt">10</span><span class="hlt">Be</span>. Existing <span class="hlt">10</span><span class="hlt">Be</span> flux records, including those from Greenland ice cores, exhibit solar variability on a range of time scales. Because this variability is globally synchronous, a <span class="hlt">10</span><span class="hlt">Be</span> flux record for the NAVC can, in principle, be used to align NAVC and ice core timescales. We are generating such a record at present. First, we are analyzing short varve sections at high temporal resolution to evaluate the magnitude of solar variability signals; a single section analyzed so far displays interannual variability with a period consistent</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....1315F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....1315F"><span id="translatedtitle">Arctic ocean water mass distribution and particle flux from dissolved <span class="hlt">10</span><span class="hlt">Be</span> and 9Be</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Frank, M.; Porcelli, D.; Andersson, P.; Halliday, A. N.; Kubik, P. W.; Hattendorf, B.; Guenther, D.</p> <p>2003-04-01</p> <p>The Arctic Ocean basin is confined by landmasses similar to the Mediterranean. There is only little deep water formed seasonally on the shelves of the Arctic Ocean despite the low temperatures. This is due to a freshwater lid at the surface which originates from the Arctic rivers. The deeper Arctic Ocean water masses can thus only be renewed at comparatively low rates via the only deep connection to the Atlantic Ocean, the Fram Strait. At the same time the biogenic particulate fluxes in the central Arctic Ocean are very low due to perennial sea ice cover and detrital particle fluxes from either eolian or riverine sources are also very low. We will present the first combined dissolved <span class="hlt">10</span><span class="hlt">Be</span> (cosmogenic) and ^9Be (continental sources) depth profiles from water samples of the major deep basins of the Arctic Ocean collected during the Swedish Arctic Ocean 2001 expedition. Be is 5-10 times less particle-reactive than other previously investigated radionuclides such as Th or Pa and should therefore even at the relatively low Arctic Ocean renewal rates serve as a quasi-conservative tracer for different origins of water masses (Atlantic Ocean/Norwegian Sea, Pacific Ocean, Arctic Shelves). ^9Be and Nd isotope analyses provide complementary information to cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> on the pathways of dissolved material originating from the Arctic continents. Results obtained ten years ago at similar locations as in our study indicated a uniform distribution of <span class="hlt">10</span><span class="hlt">Be</span> at low values of 500±100 atoms/g suggesting restricted input and efficient homogenisation. In contrast, our new results show that in 2001 the inflowing waters from the Atlantic are traced by <span class="hlt">10</span><span class="hlt">Be</span> concentrations of up to 1100 atoms/g. Preliminary measurements indicate relatively low ^9Be concentrations around 10 pMol/litre resulting in <span class="hlt">10</span><span class="hlt">Be</span>/^9Be ratios of ˜ 1 x 10-7 in the deep Arctic Ocean. In addition, the surface <span class="hlt">10</span><span class="hlt">Be</span> concentrations vary considerably. It will be discussed wether this is a consequence of a seasonal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.9351S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9351S"><span id="translatedtitle">Headwall erosion rates from cosmogenic (<span class="hlt">10</span>) <span class="hlt">Be</span> in supraglacial debris, Chhota Shigri Glacier, Indian Himalaya</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scherler, Dirk; Egholm, David</p> <p>2016-04-01</p> <p>Debris-covered glaciers are widespread within the Himalaya and other steep mountain ranges. They testify to active erosion of ice-free bedrock hillslopes that tower above valley glaciers, sometimes more than 1 km high. It is long known that debris cover significantly reduces surface ablation rates and thereby influences glacial mass balances; but its dynamic evolution along with climatic and topographic changes is poorly studied. Better understanding the coupling of ice-free bedrock hillslopes and glaciers in steep mountains requires means to assess headwall erosion rates. Here, we present headwall erosion rates derived from <span class="hlt">10</span><span class="hlt">Be</span> concentrations in the ablation-dominated medial moraine of the Chhota Shigri Glacier, Indian Himalaya. We combine our empirical, field-based approach with a numerical model of headwall erosion and glacial debris transport to assess permissible patterns of headwall erosion on the ice-free bedrock hillslopes surrounding the Chhota Shigri Glacier. Our five samples, each separated by approximately 500 m along the glacier, consist of an amalgamation of >1000 surface clasts with grain sizes between ˜1 and ˜30 mm that were taken from the medial moraine. Our results show that <span class="hlt">10</span><span class="hlt">Be</span> concentrations increase downglacier from ˜3×104 to ˜6×104 atoms g-1, yielding headwall erosion rates of ˜1.3-0.6 mm yr-1. The accumulation of <span class="hlt">10</span><span class="hlt">Be</span> during debris residence on the ice surface can only account for a small fraction (<20%) of the downglacier increase. Other potential explanations include (1) heterogeneous source areas with differences average productions rates, and (2) homogeneous source areas but temporally variable headwall erosion rates. We use the <span class="hlt">10</span><span class="hlt">Be</span>-derived headwall erosion rates to define debris supply rates from ice-free bedrock hillslopes in the numerical ice model iSOSIA. Headwall debris that is deposited in the ablation zone of the ice surface becomes englacial, is passively advected with the ice and emerges in the ablation zone where it</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.6381L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.6381L"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> Content in Suevite Breccia from the Bosumtwi Impact Crater</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Losiak, Anna; Wild, Eva Maria; Michlmayr, Leonard; Koeberl, Christian</p> <p>2013-04-01</p> <p>Introduction: According to the current understanding of meteorite impact processes, surface target material is transported from a crater in the form of ejecta or is vaporized/melted (e.g., [1]). The formation model of tektites from the surface of the target rocks has been established using the <span class="hlt">10</span><span class="hlt">Be</span> content of tektites (e.g., [2]), and chemical comparison with the possible target surface material (e.g., [3]); it was also reproduced by computer modeling (e.g., [4]). On the other hand, some observations ([5, 6]) suggest that part of the surface material may be incorporated into the crater-fill. The aim of this study is to check if surface-derived material is present in suevitic breccias to better understand formation mechanisms of fallback breccias. Also, <span class="hlt">10</span><span class="hlt">Be</span> can be used to trace contamination of rocks in the top layer of the suevitic layer by meteoric (lake) water. This abstract is an update (based on more data now available) of the previous report presented during the Metsoc75 conference. Samples: The Bosumtwi crater was chosen as study site because of its relatively large size (10.5 km in diameter), young age of 1.07 Ma [7], good state of preservation, and availability of core samples. Clasts from suevitic breccia selected for this study come from the LB-07A and LB-08A cores that are located within the crater and represent fallback breccia (e.g., [7]). Of 41 analyzed samples (22 single clasts and 21 matrix samples - 11 of those being monomictic breccia), 36 came from core LB-07A (in the zone outside the central uplift) and represent depths of 333.7 - 407.9 m and 5 are from core LB-08A (on the flank of the central uplift) from depths 239.5 - 264.9 m. Methods: For each sample, 0.8 g of finely grounded material from clasts containing in situ produced and meteoric <span class="hlt">10</span><span class="hlt">Be</span> was dissolved in a mixture of HF and HNO3 by microwave digestion. A 9Be carrier (1 mg or 0.6 mg, <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio: 2.82±0.31*10-15 [2? uncertainty]) was added to the sample, and then Be was chemically</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhG...43i5201D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhG...43i5201D"><span id="translatedtitle">Radiative <span class="hlt">10</span><span class="hlt">Be</span>(n, γ)11Be capture at thermal and astrophysical energies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dubovichenko, S. B.; Dzhazairov-Kakhramanov, A. V.</p> <p>2016-09-01</p> <p>The modified potential cluster model with the forbidden states and the classification of states according to the Young tableaux, which are irreducible representations of permutation symmetric group SU(4), was used in this paper. Within the framework of this model the possibility of describing the experimental data available for the total reaction cross sections and the reaction rate of neutron radiative capture on <span class="hlt">10</span><span class="hlt">Be</span> at thermal and astrophysical energies has been shown.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.T12B..04V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.T12B..04V"><span id="translatedtitle">Dynamics of erosion in a compressional mountain range revealed by <span class="hlt">10</span><span class="hlt">Be</span> paleoerosion rates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Val, P.; Hoke, G. D.; Fosdick, J. C.; Wittmann, H.</p> <p>2015-12-01</p> <p>The temporal evolution of erosion over million-year timescales is key to understanding the evolution of mountain ranges and adjacent fold-and-thrust belts. While models of orogenic wedge evolution predict an instantaneous response of erosion to pulses of rock uplift, stream-power based landscape evolution models predict catchment-wide erosion maxima that lag behind a rock uplift pulse. Here, we explore the relationships between rock uplift, erosion, and sediment deposition in the Argentine Precordillera fold-and-thrust belt at 30°S where extensive previous work documents deformation, climate and sediment accumulation histories. Sandstone samples spanning 8.8 to 1.8 Ma were collected from the previously dated wedge-top (Iglesia) and foredeep basins (Bermejo) for quartz purification and <span class="hlt">10</span><span class="hlt">Be</span> extraction. <span class="hlt">10</span><span class="hlt">Be</span> concentrations due to burial and exhumation were estimated and subtracted from the measured concentrations and yielded the inherited <span class="hlt">10</span><span class="hlt">Be</span> concentrations, which were then corrected for sample magnetostratigraphic age. The inherited concentrations were then used to calculate paleoerosion rates. We modeled various pre-burial and post-burial exposure scenarios in order to assess potential sources of uncertainty in the recovered paleoerosion rates. The modeling results reveal that pre-burial and post-burial exposure periods only marginally affect our results. By combining the <span class="hlt">10</span><span class="hlt">Be</span>-derived paleoerosion rates and geomorphic observations with detrital zircon provenance, we document the isolation of the wedge-top basin, which was later reconnected by an upstream migrating pulse of erosion in a process that was directly controlled by thrust activity and base level. The data further indicate that the attainment of maximum upland erosion rates lags maximum rates of deformation and subsidence over million-year timescales. The magnitudes and causes of the erosional delays shed new light on the catchment erosional response to tectonic deformation and rock uplift in orogenic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.9343H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9343H"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> exposure dating of Holocene moraines in the Sierra Nevada, California</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hidy, Alan; Zimmerman, Susan; Finkel, Robert; Schaefer, Jeorg; Clark, Douglas</p> <p>2016-04-01</p> <p>Constraint on the extent and timing of Holocene glaciations is critical to addressing standing hypotheses that ascribe climatic fluctuations to changes in atmospheric and oceanic circulation patterns, or anthropogenic forcing. In the terrestrial record, such constraint typically relies on chronologies obtained from <span class="hlt">10</span><span class="hlt">Be</span> exposure dating of moraine deposits. However, the short exposure time of Holocene moraines, particularly those formed during the Little Ice Age (LIA), makes obtaining precise chronologies extremely challenging. To date, only a handful of LIA deposits in two locations (New Zealand and the Swiss Alps) have been successfully dated with <span class="hlt">10</span><span class="hlt">Be</span>. Here, we report new <span class="hlt">10</span><span class="hlt">Be</span> exposure ages from LIA and Neoglacial moraines from multiple sites in the Sierra Nevada (Lyell, Maclure, and Palisade glaciers). The Sierran LIA record will be compared to those from New Zealand and the Swiss Alps to test whether LIA deglaciation was globally synchronous. This result would support the contention that the LIA was terminated by anthropogenically-driven warming. Chronology from the neoglacial deposits will be used to test whether the timing of the return to glacial conditions in the Sierras correlates to a southward shift in the Intertropical Convergence Zone, which has been hypothesized to increase El Nino-like conditions in the Pacific Ocean. This record should be ideal for testing this hypothesis since precipitation in the Sierras is highly sensitive to El Nino conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGP21A3642Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGP21A3642Z"><span id="translatedtitle">Brunhes-Matuyama Magnetic Polarity Reversal Tracing using Chinese loess<span class="hlt">10</span><span class="hlt">Be</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, W.; Beck, W.; Kong, X.; An, Z.; Qiang, X.; Wu, Z.; Xian, F.; Ao, H.</p> <p>2014-12-01</p> <p>The geomagnetic polarity reversal is generally considered to occur synchronously around the world, and is commonly used as a time marker. However, in the case of the most recent reversal, the Brunhes-Matuyama (B-M) reversal (~780 ka), comparison of paleomagnetic studies in Chinese loess-paleosol sequences versus marine sediments revealed a marked discrepancy in timing of this event (Tauxe et al., 1996; Zhou and Shackleton, 1999), leading to the debate on uncertainties of paleoclimatic correlation between the Chinese loess-paleosol sequences and marine sediments (Wang et al., 2006; Liu et al., 2008; Jin and Liu, 2011). Based on this issue, here we propose to use the cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> to address this conundrum. <span class="hlt">10</span><span class="hlt">Be</span> is a long-lived radionuclide produced in the atmosphere by cosmic ray spallation reactions and carried to the ground attached to aerosols. Its atmospheric production rate is inversely proportional to the geomagnetic field intensity (Masarik and Beer, 1999). This allows us to reconstruct past geomagnetic field intensity variations using <span class="hlt">10</span><span class="hlt">Be</span> concentrations recorded in different sedimentary archives. We carried out the <span class="hlt">10</span><span class="hlt">Be</span> studies in Luochuan and Xifeng sections in Chinese Loess Plateau, both loess profiles show that <span class="hlt">10</span><span class="hlt">Be</span> production rate was at a maximum-an indication of the dipole field reversal-at ca. 780 ± 3 ka BP., in paleosol unit S7corresponding to MIS 19. These results have proven that the timing of B-M reversal recorded in Chinese loess is synchronous with that seen in marine records (Tauxe et al., 1996) and reaffirmed the conventional paleoclimatic correlation of loess-paleosol sequences with marine isotope stages and the standard loess timescale as correct. However, it is ~25 ka younger than the age (depth) of the magnetic polarity reversal recorded in these same Chinese loess-paleosol sequences, demonstrating that loess magnetic overprinting has occurred. 1.Jin, C.S.,et al., 2011,PALAEOGEOGR PALAEOCL, 299, 309-3172.Liu, Q.S., et al., 2008, EARTH</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMGP42A..02Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMGP42A..02Z"><span id="translatedtitle">Loess <span class="hlt">10</span><span class="hlt">Be</span> evidence for an asynchronous Brunhes-Matuyama magnetic polarity reversal</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, W.; Beck, W.; Kong, X.; An, Z.; Qiang, X.; Wu, Z.; Xian, F.; Ao, H.</p> <p>2015-12-01</p> <p>In Chinese loess the Brunhes-Matuyama (B-M) geomagnetic reversal appears to occur about 25 ka prior to the established axial dipole reversal age found in many marine sediments, i.e., in Chinese loess this magnetic reversal boundary is found in glacial loess unit L8 which is thought to be correlated with Marine Isotope Stage 20 (MIS 20), in marine sediment records, however, this boundary is commonly found in interglacial period of MIS 19[1-2], leading to the debate on uncertainties of paleoclimatic correlation between the Chinese loess-paleosol sequences and marine sediments[3-5]. Based on this issue, here we propose to use the cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> to address this conundrum. <span class="hlt">10</span><span class="hlt">Be</span> is a long-lived radionuclide produced in the atmosphere by cosmic ray spallation reactions and carried to the ground attached to aerosols. Its atmospheric production rate is inversely proportional to the geomagnetic field intensity [6]. This allows us to reconstruct past geomagnetic field intensity variations using <span class="hlt">10</span><span class="hlt">Be</span> concentrations recorded in different sedimentary archives. We carried out both the <span class="hlt">10</span><span class="hlt">Be</span> studies and paleogeomagnetic measurements in Luochuan and Xifeng sections in Chinese Loess Plateau. Both loess profiles show that <span class="hlt">10</span><span class="hlt">Be</span> production rate was at a maximum-an indication of the dipole field reversal-at ca. 780 ± 3 ka BP., in paleosol unit S7 corresponding to MIS 19, proving that the timing of B-M reversal recorded in Chinese loess is synchronous with that seen in marine records [1]. These results reaffirmed the conventional paleoclimatic correlation of loess-paleosol sequences with marine isotope stages and the standard loess timescale as correct. However, it is ~25 ka younger than the age (depth) of the paleogeomagnetic measurements, which show that the B-M boundary is in L8 in these two Chinese loess-paleosol sequences, demonstrating that loess magnetic overprinting has occurred. 1.Tauxe, L., et al., 1996, EARTH PLANET SC LETT, 140, 133-1462.Zhou, L.P., and Shackleton, 1999</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMEP21B3541W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMEP21B3541W"><span id="translatedtitle">Detrital <span class="hlt">10</span><span class="hlt">Be</span> Response to the 2008 Wenchuan Earthquake and Quantifying Evacuation of Coseismic Landslide Debris</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, W.; Godard, V.; Liu-Zeng, J.; Scherler, D.; Xu, C.; Xu, Q.; Xie, K.; Bellier, O.; Bourles, D. L.; Ansberque, C.</p> <p>2014-12-01</p> <p>In reverse fault-bounded high relief mountain ranges, large-magnitude earthquakes contribute to the topographic growth by co- and inter-seismic surface uplift on the hanging wall. Meanwhile, they also trigger widespread landslides along ridge lines or hillslopes. Coseismic landsliding lowers relief and causes a phase of high erosion in the period following the quake. The net effect of large-magnitude earthquakes in topographic evolution of active orogens partially depends on how fast the landslide debris are being evacuated out of the mountain range. The 2008 Mw7.9 Wenchuan earthquake, China activated the Longmen Shan reverse fault system in eastern Tibetan plateau, also induced enormous amount of landslides, volume comparable to the coseismic uplift, providing an excellent opportunity to address the question. We use cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> concentration in river sand as a tracer to study the sediment routing process of coseismic landslide debris, because landslide debris contains low <span class="hlt">10</span><span class="hlt">Be</span> concentration. We sampling annually during 2008-2013, at 19 locations along the rivers that traverse the fault ruptures, with upstream catchment area varying between 4.4 km2 and 21775 km2, including 10 catchments sampled before Wenchuan earthquake in 2004 and 2005. A comparison with pre-earthquake measurements show reduced <span class="hlt">10</span><span class="hlt">Be</span> concentration at all sites. This dilution is more significant for small catchments on short range-front rivers: mostly half to one-fourth, and down to one-fifth in some cases. Multi-year time series of <span class="hlt">10</span><span class="hlt">Be</span> concentration at single sites show roughly constant level of dilution six years after the quake, with moderate temporal fluctuations, which may be related to the variation in precipitation and storm intensity. Under the assumption of constant dilution rate and a depth-mixing of <span class="hlt">10</span><span class="hlt">Be</span> concentration for landslide input, a simple calculation indicates it would take ~ 200 to 3000 years to completely evacuate the landslides debris within range-front transverse rivers</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.184..151K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.184..151K"><span id="translatedtitle">New constraints on the relationship between <span class="hlt">26</span><span class="hlt">Al</span> and oxygen, calcium, and titanium isotopic variation in the early Solar System from a multielement isotopic study of spinel-hibonite inclusions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kööp, Levke; Nakashima, Daisuke; Heck, Philipp R.; Kita, Noriko T.; Tenner, Travis J.; Krot, Alexander N.; Nagashima, Kazuhide; Park, Changkun; Davis, Andrew M.</p> <p>2016-07-01</p> <p>We report oxygen, calcium, titanium and <span class="hlt">26</span><span class="hlt">Al</span>-26Mg isotope systematics for spinel-hibonite inclusions (SHIBs), a class of calcium-aluminum-rich inclusions (CAI) common in CM chondrites. In contrast to previous studies, our analyses of 33 SHIBs and four SHIB-related objects obtained with high spatial resolution demonstrate that these CAIs have a uniform Δ17O value of approximately -23‰, similar to many other mineralogically pristine CAIs from unmetamorphosed chondrites (e.g., CR, CV, and Acfer 094). Five SHIBs studied for calcium and titanium isotopes have no resolvable anomalies beyond 3σ uncertainties. This suggests that nucleosynthetic anomalies in the refractory elements had been significantly diluted in the environment where SHIBs with uniform Δ17O formed. We established internal <span class="hlt">26</span><span class="hlt">Al</span>-26Mg isochrons for eight SHIBs and found that seven of these formed with uniformly high levels of <span class="hlt">26</span><span class="hlt">Al</span> (a multi-CAI mineral isochron yields an initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio of ∼4.8 × 10-5), but one SHIB has a smaller initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al of ∼ 2.5 × 10-5, indicating variation in <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios when SHIBs formed. The uniform calcium, titanium and oxygen isotopic characteristics found in SHIBs with both high and low initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios allow for two interpretations. (1) If subcanonical initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios in SHIBs are due to early formation, as suggested by Liu et al. (2012), our data would indicate that the CAI formation region had achieved a high degree of isotopic homogeneity in oxygen and refractory elements before a homogeneous distribution of <span class="hlt">26</span><span class="hlt">Al</span> was achieved. (2) Alternatively, if subcanonical ratios were the result of <span class="hlt">26</span><span class="hlt">Al</span>-26Mg system resetting, the clustering of SHIBs at a Δ17O value of ∼-23‰ would imply that a 16O-rich gaseous reservoir existed in the nebula until at least ∼0.7 Ma after the formation of the majority of CAIs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.H43A1216M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.H43A1216M"><span id="translatedtitle">Pore water dating by 129I: What do <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio, dissolved 4He concentration, δ37Cl and 129I/127I ratio suggest in the Mobara Gas field, Japan?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mahara, Y.; Ohta, T.; Tokunaga, T.</p> <p>2010-12-01</p> <p>Total 24-brine samples were collected from hot springs and the Mobara gas wells in the Southern Kanto Gas field, where is not only the major production area for dissolved natural gas in Japan but for iodine in the world. Isotopic ratios of 129I/127I and <span class="hlt">36</span><span class="hlt">Cl</span>/Cl, and noble gases concentration dissolved into pore water were measured for estimating residence time of brine. Iodine concentration in brines increases from 10 mg/L in the northern Kanto plain to more than 100 mg/L in the south edge of the gas field, and finally reaches 170 mg/L. In contrast, the isotopic ratio of 129I/127I decreases 5×10-13 in north to 1.7×10-13 in south. Both distributions were presumably controlled by the thickness of the Kazusa group as natural gas reservoirs. The average 129I/127I ratio was estimated to be 2.33 ± 0.11×10-13 at the Mobara area. Average ages of brines are estimated to be 42 Ma by using the initial 129I/127I ratio (1.5×10-12), if the origin of 129I were cosmogenic. On the other hand, we deduced 0.2 - 0.9 Ma as the residence time of brine from comparison with the secular equilibrium <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio (6.46 ± 2.24×10-15) for the reservoir formation of Pleistocene. The concentration of 4He dissolved in pore water in the bored rock core suggests that residence time of brines vertically ranges 0.12 - 1.05 Ma and it is also harmonized with the formation age (of 0.45 - 2.5 Ma). Furthermore, δ37Cl (- 0.14±0.13 ~ + 0.45±0.07 ‰) in pore water were measured under the chloride concentration increasing 5000 mg/L to 17000 mg/L at the depth from 642 m to 1902 m below the ground surface. The simulating analyses of δ37Cl was conducted under the boundary conditions of washing out by freshwater at the depth of 600 m below the ground surface, chloride concentration gradient of 17000/500 (mg/L/m) and diffusion alone without advection flow during the past 0.12 Ma. The fractionation factor for 35Cl and 37Cl was 1.0012 (Desauliniers et al., 1986). The analyses indicated that the</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.C53A0829B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.C53A0829B"><span id="translatedtitle">A <span class="hlt">10</span><span class="hlt">Be</span> Chronology of Late Pleistocene and Holocene Glaciation in the Rwenzori Mountains, Uganda</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baber, M.; Kelly, M. A.; Russell, J. M.; Loomis, S. E.</p> <p>2012-12-01</p> <p>Although the retreat of glaciers in East Africa has been monitored over the last century, longer-term records of African glacier fluctuations are scarce. The Rwenzori Mountains, located on the border of Uganda and the Democratic Republic of Congo, host the largest glacial system in Africa and provide an opportunity for extensive investigation of past glaciations. We mapped and applied surface exposure (<span class="hlt">10</span><span class="hlt">Be</span>) dating to glacial moraines deposited since the end of the last ice age in the Rwenzori Mountains to test the feasibility of <span class="hlt">10</span><span class="hlt">Be</span> dating at this site and to develop a chronology of glacial fluctuations. Our study is the first to use <span class="hlt">10</span><span class="hlt">Be</span> dating of glacial features in Africa and is possible because the Rwenzori host quartz-rich lithologies. By comparing the timing of Rwenzori glacial advances with other paleoclimate records from East Africa, we also will examine the climatic conditions which influenced tropical glacier fluctuations. Osmaston (1989) mapped moraines in the Rwenzori Mountains, documenting three stages of Pleistocene and Holocene glaciations, the Mahoma, Omurubaho and Lac Gris stages. The Mahoma stage moraines are estimated to be older than 17,980 ± 780 yr BP (D. M. Livingstone, 1962) by basal 14C dating of sediments from Lake Mahoma, situated in large lateral moraine at 2990 m asl. The age of the Omurubaho stage moraine is estimated from a basal 14C age (7,730 ± 150 yr BP) Lower Kitandara Lake (3990 m asl) and dammed by an Omurubaho stage moraine. The Lac Gris moraines are estimated at ~150-700 yr BP (de Heinzelin, 1953; Bergström, 1955) based on rates of lichen growth and plant colonization on moraines about 200 m below current glacial positions on Mt. Stanley. Though considerable uncertainty remains for the ages of these glacier deposits, these three stages most likely represent ages from the LGM to the LIA. We present two new <span class="hlt">10</span><span class="hlt">Be</span> ages of boulders from two moraines in the Nyamagusani Valley, ~4000 m asl. Sample KOP-2 (4033 m asl) is from the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016QSRv..138..105L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016QSRv..138..105L"><span id="translatedtitle">Cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> constraints on Little Ice Age glacial advances in the eastern Tian Shan, China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Yanan; Li, Yingkui; Harbor, Jon; Liu, Gengnian; Yi, Chaolu; Caffee, Marc W.</p> <p>2016-04-01</p> <p>Presumed Little Ice Age (LIA) glacial advances, represented by a set of fresh, sharp-crested, boulder covered and compact moraines a few hundred meters downstream from modern glaciers, have been widely recognized in the Central Asian highlands. However, few studies have constrained the formation ages of these moraines. We report 31 <span class="hlt">10</span><span class="hlt">Be</span> exposure ages from presumed LIA moraines in six glacial valleys in the Urumqi River headwater area and the Haxilegen Pass area of the eastern Tian Shan, China. Our results reveal that the maximum LIA glacial extent occurred mainly around 430 ± 100 yr, a cold and wet period as indicated by proxy data from ice cores, tree rings, and lake sediments in Central Asia. We also dated a later glacial advance to 270 ± 55 yr. However, <span class="hlt">10</span><span class="hlt">Be</span> exposure ages on several presumed LIA moraines in front of small, thin glaciers are widely scattered and much older than the globally recognized timing of the LIA. Historical topographic maps indicate that most glaciers were more extensive in the early 1960s, and two of our <span class="hlt">10</span><span class="hlt">Be</span> sample sites were located close to the ice front at that time. Boulders transported by these small and thin glaciers may be reworked from deposits originally formed prior to the LIA glacial advances, producing apparently old and widely scattered exposure ages due to varied nuclide inheritance. Other published ages indicated an earlier LIA advance around 790 ± 300 yr in the easternmost Tian Shan, but in our study area the more extensive advance around 430 ± 100 yr likely reworked or covered deposits from this earlier event.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMEP23F..08H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMEP23F..08H"><span id="translatedtitle">Millennial Rates of Sea Cliff Retreat Derived From Cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> and Coastal Platform Morphology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hurst, M. D.; Ellis, M. A.; Rood, D. H.</p> <p>2014-12-01</p> <p>Observation of cliff erosion are often limited to relatively short timescales (a few decades), which are within the timeframe of anthropogenic modification of the coast and may be shorter than the recurrence interval for erosion events. Here we present long-term (centennial-millennial) averaged rates of sea cliff retreat for chalk cliffs in SE England derived from cosmogenic isotopes and coastal morphology. We determine long-term rates of sea cliff erosion from <span class="hlt">10</span><span class="hlt">Be</span> measured from in situ flint samples collected from three transects across the coastal platform in East Sussex. A numerical model of <span class="hlt">10</span><span class="hlt">Be</span> accumulation on an evolving coastal profile allows estimation of cliff retreat rate averaged over several hundred years. The model accounts for variation in <span class="hlt">10</span><span class="hlt">Be</span> accumulation with tides and sea-level rise, and takes into account platform downwear and topographic shielding by adjacent cliffs. Additionally, we use high-resolution (1m) multibeam bathymetry to map the extent of the coastal platform based on the surface texture in order to infer the position of the coast at ~8 ka. The difference in position to the current coastline provides estimates of Holocene-averaged rates of cliff erosion for all chalk cliffed coastline in the region. Comparison to historic records of cliff retreat reveals key similarities and differences between long and short-term signals. In certain locations, there are significant discrepancies (either faster or slower) between historic records and long-term rates of retreat. Each type of discrepancy may be the result of human interaction with the coastal environment, whether that interaction is local or non-local, and it is worthwhile noting that sites of relatively low historic rates of erosion are likely subject to high-magnitude, low-frequency failure events that could have devastating effects on human lives and infrastructure in areas that are considered to be low risk.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15148365','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15148365"><span id="translatedtitle">Flint mining in prehistory recorded by in situ-produced cosmogenic <span class="hlt">10</span><span class="hlt">Be</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Verri, G; Barkai, R; Bordeanu, C; Gopher, A; Hass, M; Kaufman, A; Kubik, P; Montanari, E; Paul, M; Ronen, A; Weiner, S; Boaretto, E</p> <p>2004-05-25</p> <p>The development of mining to acquire the best raw materials for producing stone tools represents a breakthrough in human technological and intellectual development. We present a new approach to studying the history of flint mining, using in situ-produced cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> concentrations. We show that the raw material used to manufacture flint artifacts approximately 300,000 years old from Qesem Cave (Israel) was most likely surface-collected or obtained from shallow quarries, whereas artifacts of the same period from Tabun Cave (Israel) were made of flint originating from layers 2 or more meters deep, possibly mined or quarried by humans.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMPP33A2291G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMPP33A2291G"><span id="translatedtitle">Improved Timing of Deglaciation of the Southwestern Scandinavian Ice Sheet Using <span class="hlt">10</span><span class="hlt">Be</span> Dating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gump, D.; Briner, J. P.; Svendsen, J. I.; Mangerud, J.</p> <p>2015-12-01</p> <p>We present 28 new <span class="hlt">10</span><span class="hlt">Be</span> ages from glacial erratic boulders to constrain Scandinavian Ice Sheet deglaciation along the major fjord system of Boknafjorden in southwest Norway. Results indicate ages in the range 20-14 ka and complement our previous findings that the Norwegian Channel Ice Stream (NCIS) had retreated some 400 km as early as ~20 ka (Svendsen et al., 2015) and further corroborate that this was followed by a second pulse of deglaciation at ~16 ka. After the immediate coast was rendered an ice-free corridor at ~20 ka, our new suite of ages identifies ~16 ka as a period of a possible culmination of re-advance, and almost certainly the onset of a subsequent period of retreat. These findings are promising for the possibility of long lake sediment archives from areas around the mouth of Boknafjorden. Additionally, by coupling our new <span class="hlt">10</span><span class="hlt">Be</span> ages of erratic boulders from sea level and from summits bordering Boknafjorden with topographic profiles and rudimentary ice-sheet profile calculations (Benn and Hulton, 2010), we are able to estimate spatial and temporal Scandinavian Ice Sheet history along both vertical and horizontal transects. Our results not only fill chronological gaps and add to a growing database of ages of deglaciation from the southwest Norway, but also provide new constraints for a three-dimensional reconstruction of the Scandinavian Ice Sheet during deglaciation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004NIMPB.223..591S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004NIMPB.223..591S"><span id="translatedtitle">Meteoric <span class="hlt">10</span><span class="hlt">Be</span> in volcanic materials and its behavior during acid-leaching</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shimaoka, Akiko; Sakamoto, Minoru; Hiyagon, Hajime; Matsuzaki, Hiroyuki; Kaneoka, Ichiro; Imamura, Mineo</p> <p>2004-08-01</p> <p>We have investigated the chemical and isotopic behavior of beryllium (Be) during acid leaching for removing meteoric <span class="hlt">10</span><span class="hlt">Be</span> in volcanic samples. Determination of the Be isotopic ratio in the leachate was carried out using accelerator mass spectrometry (AMS) and inductivity coupled plasma mass spectrometer (ICP-MS). Elemental distribution of Be and other incompatible elements including boron (B) were also examined by ion microprobe (SIMS) for a deeper understanding of their chemical behavior in volcanic samples. SIMS analysis show that Be is concentrated in the groundmass together with B. However, the behavior of their elements during acid leaching is quite different. The Be concentration decreases through progressive leaching, while the concentration of B remains constant. Furthermore, the variation in the Be isotopic ratio after acid leaching is different between the two samples, neither of which has altered minerals under microscopic observation. It is demonstrated that meteoric <span class="hlt">10</span><span class="hlt">Be</span> resides in a rather narrow region of the rock and can be removed by acid leaching with minimum loss of the main host phase of Be.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NIMPB.371..370B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NIMPB.371..370B"><span id="translatedtitle">Studies of Be migration in the JET tokamak using AMS with <span class="hlt">10</span><span class="hlt">Be</span> marker</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bykov, I.; Bergsåker, H.; Possnert, G.; Zhou, Y.; Heinola, K.; Pettersson, J.; Conroy, S.; Likonen, J.; Petersson, P.; Widdowson, A.</p> <p>2016-03-01</p> <p>The JET tokamak is operated with beryllium limiter tiles in the main chamber and tungsten coated carbon fiber composite tiles and solid W tiles in the divertor. One important issue is how wall materials are migrating during plasma operation. To study beryllium redistribution in the main chamber and in the divertor, a <span class="hlt">10</span><span class="hlt">Be</span> enriched limiter tile was installed prior to plasma operations in 2011-2012. Methods to take surface samples have been developed, an abrasive method for bulk Be tiles in the main chamber, which permits reuse of the tiles, and leaching with hot HCl to remove all Be deposited at W coated surfaces in the divertor. Quantitative analysis of the total amount of Be in cm2 sized samples was made with inductively coupled plasma atomic emission spectroscopy (ICP-AES). The <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio in the samples was measured with accelerator mass spectrometry (AMS). The experimental setup and methods are described in detail, including sample preparation, measures to eliminate contributions in AMS from the 10B isobar, possible activation due to plasma generated neutrons and effects of diffusive isotope mixing. For the first time marker concentrations are measured in the divertor deposits. They are in the range 0.4-1.2% of the source concentration, with moderate poloidal variation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1715897Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1715897Z"><span id="translatedtitle">Loess <span class="hlt">10</span><span class="hlt">Be</span> evidence for an asynchronous Brunhes-Matuyama magnetic polarity reversal</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, Weijian; Beck, J. Warren; Kong, Xianghui; An, Zhisheng; Qiang, Xiaoke; Wu, Zhenkun; Xian, Feng; Ao, Hong</p> <p>2015-04-01</p> <p>In Chinese loess the Brunhes-Matuyama (B-M) geomagnetic reversal appears to occur about 25 ka prior to the established axial dipole reversal age found in many marine sediments, i.e., in Chinese loess this magnetic reversal boundary is found in glacial loess unit L8 which is thought to be correlated with Marine Isotope Stage 20 (MIS 20), in marine sediment records, however, this boundary is commonly found in interglacial period of MIS 19 (Tauxe et al., 1996; Zhou and Shackleton, 1999), leading to the debate on uncertainties of paleoclimatic correlation between the Chinese loess-paleosol sequences and marine sediments (Wang et al., 2006; Liu et al., 2008; Jin and Liu, 2011). Based on this issue, here we propose to use the cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> to address this conundrum. <span class="hlt">10</span><span class="hlt">Be</span> is a long-lived radionuclide produced in the atmosphere by cosmic ray spallation reactions and carried to the ground attached to aerosols. Its atmospheric production rate is inversely proportional to the geomagnetic field intensity (Masarik and Beer, 1999). This allows us to reconstruct past geomagnetic field intensity variations using <span class="hlt">10</span><span class="hlt">Be</span> concentrations recorded in different sedimentary archives. We carried out both the <span class="hlt">10</span><span class="hlt">Be</span> studies and paleogeomagnetic measurements in Luochuan and Xifeng sections in Chinese Loess Plateau. Both loess profiles show that <span class="hlt">10</span><span class="hlt">Be</span> production rate was at a maximum-an indication of the dipole field reversal-at ca. 780 ± 3 ka BP., in paleosol unit S7 corresponding to MIS 19, proving that the timing of B-M reversal recorded in Chinese loess is synchronous with that seen in marine records (Tauxe et al., 1996). These results reaffirmed the conventional paleoclimatic correlation of loess-paleosol sequences with marine isotope stages and the standard loess timescale as correct. However, it is ~25 ka younger than the age (depth) of the paleogeomagnetic measurements which show that the B-M boundary is in L8 in these two Chinese loess-paleosol sequences, demonstrating that loess</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24909078','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24909078"><span id="translatedtitle">Biosynthesis of steroidal alkaloids in Solanaceae plants: incorporation of 3β-hydroxycholest-5-en-<span class="hlt">26</span>-<span class="hlt">al</span> into tomatine with tomato seedlings.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ohyama, Kiyoshi; Okawa, Akiko; Fujimoto, Yoshinori</p> <p>2014-08-01</p> <p>The C-26 amino group of tomatine, a representative Solanaceae steroidal alkaloid, is introduced in an early step of its biosynthesis from cholesterol. We recently proposed a transamination mechanism for the C-26 amination as opposed to the previously proposed mechanism involving a nitrogen nucleophilic displacement. In the present study, a deuterium labeled C-26 aldehyde, (24,24,27,27,27-(2)H5)-3β-hydroxycholest-5-en-<span class="hlt">26</span>-<span class="hlt">al</span>, was synthesized and fed to a tomato (Solanum lycopersicum) seedling. LC-MS analysis of the biosynthesized tomatine indicated that the labeled aldehyde was incorporated into tomatine. The finding strongly supports the intermediacy of the aldehyde and the transamination mechanism during C-26 amination.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMPP31A1843C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMPP31A1843C"><span id="translatedtitle">Cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> Age Constraints on the Holocene Deglaciation of the Scandinavian Ice Sheet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cuzzone, J. K.; Clark, P. U.; Wohlfarth, B.; Lunkka, J.</p> <p>2011-12-01</p> <p>An important question in climate science is how ice sheets will respond to a climate warmer than present. Because our understanding of how these changes will occur remains limited, reconstructing the deglaciation of former ice sheets allows for a better understanding of how past ice sheets responded to a climate warmer than present along with understanding their contribution to sea-level rise. We will present new cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> ages from erratic boulders along three transects spanning southern to northern Sweden and Finland that improve our understanding of the deglaciation of the Scandinavian Ice Sheet (SIS) beginning ~ 11.7ka through its final demise during the early Holocene. By constraining the Holocene deglaciation of the SIS and its associated retreat rates, we will establish the SIS contribution to Holocene sea level rise, improving our understanding of ice-sheet response to warming climates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70033649','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70033649"><span id="translatedtitle">Extent of the last ice sheet in northern Scotland tested with cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> exposure ages</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Phillips, W.M.; Hall, A.M.; Ballantyne, C.K.; Binnie, S.; Kubik, P.W.; Freeman, S.</p> <p>2008-01-01</p> <p>The extent of the last British-Irish Ice Sheet (BIIS) in northern Scotland is disputed. A restricted ice sheet model holds that at the global Last Glacial Maximum (LGM; ca. 23-19 ka) the BIIS terminated on land in northern Scotland, leaving Buchan, Caithness and the Orkney Islands ice-free. An alternative model implies that these three areas were ice-covered at the LGM, with the BIIS extending offshore onto the adjacent shelves. We test the two models using cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> surface exposure dating of erratic boulders and glacially eroded bedrock from the three areas. Our results indicate that the last BIIS covered all of northern Scotland during the LGM, but that widespread deglaciation of Caithness and Orkney occurred prior to rapid warming at ca. 14.5 ka. Copyright ?? 2008 John Wiley & Sons, Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMPP11A2211T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMPP11A2211T"><span id="translatedtitle">OSL and Cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> Dating of Fluvial Terraces on the Northeast Pamir Margin, Northwest China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thompson, J. A.; Chen, J.; Yang, H.; Li, T.; Bookhagen, B.; Burbank, D. W.; Bufe, A.</p> <p>2015-12-01</p> <p>Along the northeast Pamir margin in northwest China, flights of late Pleistocene fluvial terraces span actively deforming structures. We present detailed results on three terraces that we dated using optically stimulated luminescence (OSL) and cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> techniques. Quartz OSL dating of two different grain sizes (4-11 and 90-180 μm) revealed the fine-grain quartz fraction overestimates the terrace ages by up to an order of magnitude. Two-mm, small-aliquot, coarse-grain quartz OSL ages, calculated using the finite mixture model, yielded stratigraphically consistent ages within error and dated times of terrace deposition to ~15 ka, ~18.5 ka, and ~75 ka. We speculate the observed grain-size dependence of OSL ages is likely related to the mode of transport of the grains in the fluvial system, with coarser grains sizes spending more time on sand bars where they are more thoroughly bleached than grains in the turbid, commonly episodic flows that carry the silt fraction. Our study suggests that, in flashy, turbid fluvial systems, coarse-grain OSL samples are likely to yield more reliable depositional ages than will fine-grain samples. Cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> depth profiles date the times of terrace abandonment to ~8 ka, ~15 ka, and ~75 ka, yielding ages in overall agreement with the coarse-grain OSL ages. These ages are generally consistent with other dated terraces in the region that place their deposition and subsequent abandonment during the last deglaciation (13-18 ka) and suggest the formation of these terraces on the margins of the Tarim Basin and along the flanks of the Tian Shan is climatically controlled.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRF..119...83S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRF..119...83S"><span id="translatedtitle">Tectonic control on <span class="hlt">10</span><span class="hlt">Be</span>-derived erosion rates in the Garhwal Himalaya, India</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scherler, Dirk; Bookhagen, Bodo; Strecker, Manfred R.</p> <p>2014-02-01</p> <p>Erosion in the Himalaya is responsible for one of the greatest mass redistributions on Earth and has fueled models of feedback loops between climate and tectonics. Although the general trends of erosion across the Himalaya are reasonably well known, the relative importance of factors controlling erosion is less well constrained. Here we present 25 <span class="hlt">10</span><span class="hlt">Be</span>-derived catchment-averaged erosion rates from the Yamuna catchment in the Garhwal Himalaya, northern India. Tributary erosion rates range between ~0.1 and 0.5 mm yr-1 in the Lesser Himalaya and ~1 and 2 mm yr-1 in the High Himalaya, despite uniform hillslope angles. The erosion-rate data correlate with catchment-averaged values of 5 km radius relief, channel steepness indices, and specific stream power but to varying degrees of nonlinearity. Similar nonlinear relationships and coefficients of determination suggest that topographic steepness is the major control on the spatial variability of erosion and that twofold to threefold differences in annual runoff are of minor importance in this area. Instead, the spatial distribution of erosion in the study area is consistent with a tectonic model in which the rock uplift pattern is largely controlled by the shortening rate and the geometry of the Main Himalayan Thrust fault (MHT). Our data support a shallow dip of the MHT underneath the Lesser Himalaya, followed by a midcrustal ramp underneath the High Himalaya, as indicated by geophysical data. Finally, analysis of sample results from larger main stem rivers indicates significant variability of <span class="hlt">10</span><span class="hlt">Be</span>-derived erosion rates, possibly related to nonproportional sediment supply from different tributaries and incomplete mixing in main stem channels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.7819I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.7819I"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> surface exposure dating of rock glaciers in Larstigtal, Tyrol, Austria</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ivy-Ochs, S.; Kerschner, H.; Maisch, M.; Christl, M.; Kubik, P. W.; Schluchter, C.</p> <p>2009-04-01</p> <p>In the context of Lateglacial and Holocene climate change research, rock glaciers (creeping mountain permafrost) also play an important role. They are phenomena of discontinuous alpine permafrost and as such good indicators for the mean annual air temperature for the period they are active. We have <span class="hlt">10</span><span class="hlt">Be</span> surface exposure dated boulders from two relict rock glaciers in Larstigtal, Austria. This is the type area for a postulated mid-Holocene cold period called the Larstig oscillation. The period of activity was suggested to be of similar age as the mid-Holocene Frosnitz advance of glaciers in the Venediger Mountains farther to the east (Patzelt and Bortenschlager, 1973). For rock glaciers of this size to be active at 2200 m a.s.l. in Larstig valley would have required a significant drop in temperatures, thus a marked mid-Holocene cold pulse, for at least several centuries at around 7.0 ka. In contrast, our exposure dates show that the rock glaciers stabilized during the early Preboreal (Ivy-Ochs et al., submitted). We see no distinct pattern with respect to exposure age and boulder location on the rock glaciers. This implies that for our site the blocks did not acquire inherited <span class="hlt">10</span><span class="hlt">Be</span> during exposure in the free rock face, in the talus at the base of the slope, or during transport on the rock glaciers. Our data point to final stabilization of the Larstigtal rock glaciers in the earliest Holocene and not in the middle Holocene. Combined with data from other archives (Nicolussi et al., 2005), there appears to have been no time window in the middle Holocene long enough for rock glaciers of the size and at the elevation of the Larstig site to have formed. Ivy-Ochs, S., Kerschner, H., Maisch, M., Christl, M., Kubik, P.W., Schlüchter, C., Latest Pleistocene and Holocene glacier variations in the European Alps. Quaternary Science Reviews (submitted). Nicolussi, K., Kaufmann, M., Patzelt, G., van der Plicht, J., Thurner, A., 2005. Holocene tree-line variability in the Kauner</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850026781','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850026781"><span id="translatedtitle">Cosmic rays <span class="hlt">10</span><span class="hlt">Be</span> biennal data and their relationship to aurorae and sunspots</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Attolini, M. R.; Cecchini, S.; Castagnoli, G. C.; Galli, M.; Nanni, T.</p> <p>1985-01-01</p> <p>The galactic cosmic ray (C.R.) variations which should give information on three dimensional aspects of the heliospheric magnetic fields and on the solar wind, which modulate their influx into the Solar System were studied. In order to decode the information from the C.R. series it is necessary to know the mechanisms through which the modulation is produced. It it clear that a balance of effects with sources at different heliospheric latitudes results in the modulated C.R. intensity. It is found that the modulation of <span class="hlt">10</span><span class="hlt">Be</span> in polar ice may be due to at least two main contributions: (1) negative and in phase with the Solar flare activity modulating the cosmic ray flux in Forbush-type decreases, and (2) positive in phase with the appearance of large wind streams situated at both polar coronal holes. It is found that the high heliolatitude activity is related to a stable periodicity of 11.1y whereas the low heliolatitude activity contributes to the wondering of the solar cycles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.C53E..05C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.C53E..05C"><span id="translatedtitle">Holocene Deglaciation of the Scandinavian Ice Sheet: Preliminary <span class="hlt">10</span><span class="hlt">Be</span> Ages</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cuzzone, J. K.; Clark, P. U.; Marcott, S. A.; Pekka Lunka, J.; Wohlfarth, B.; Carlson, A. E.</p> <p>2012-12-01</p> <p>The response of ice sheets to a warming climate is not well understood. Because we are limited in our understanding of present dynamics, reconstructing the deglaciation of former ice sheets allows for a better understanding of how past ice sheets responded to a warming climate along with their contribution to sea-level rise. These reconstructions also serve as critical constraints for ice sheet modeling efforts. Here, we present a suite of new <span class="hlt">10</span><span class="hlt">Be</span> ages from erratic boulders along three transects spanning southern to northern Sweden and Finland, that improve our understanding of the deglaciation of the Scandinavian Ice Sheet (SIS) beginning ~ 11.7ka through its final demise during the early Holocene. Preliminary dates from southern Finland, beginning at the Salpausselka Youngers Dryas moraine (11.5 ± 0.7 ka, n=2), inland southern Finland near Jyvaskyla (11.5 ± 0.5ka, n=2), and coastal Finland (~60km from Gulf of Bothnia) near Vimpeli (11.5 ± 0.4ka, n=1) indicate a rapid retreat following the Younger Dryas for Southern Finland (~500km within uncertainty of ages). Preliminary dates also exist for Northern Finland, near Inari (10.3 ± 0.5ka, n=2). Additional ages now being processed at PRIME Lab, Purdue University, which will establish a basis for SIS retreat from all sampled sites, will also be presented. These new data will help to constrain the Holocene deglaciation of the SIS and its associated retreat rates, and establish the SIS contribution to Holocene sea level rise, which will improve our understanding of ice-sheet response to a warming climate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMNH31C..04H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMNH31C..04H"><span id="translatedtitle">Examples of sackungen in the French Western Alps and their geochronology based on the <span class="hlt">10</span><span class="hlt">Be</span> cosmic ray exposure dating method (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hippolyte, J.; Bourles, D. L.; Braucher, R.; Léanni, L.; Chauvet, F.; Lebatard, A.; Arnold, M.; Aumaître, G.; Keddadouche, K.</p> <p>2013-12-01</p> <p>In the French Alps, sackung scarps were often interpreted as surface traces of active faults. A detailed mapping of the Arc and Rognier mountains shows that these scarps result from deep-seated gravitational slope deformation (DSGSD). They are short (less than 2.1 km long), numerous and organized in swarms (5.3 km long at the Arc; 9 km long at Rognier). There are mainly uphill facing scarps developed on steep slopes. Open tension cracks are present at ridge tops. These sackung fractures created ridge-top troughs, closed depressions and multiple-crests landforms. That the sackung scarps are parallel to the contour lines, and that they result from opening of fractures or from normal slips, indicates that they are controlled by topography and gravity. In the Western Alps, glacial erosion and subsequent debuttressing of oversteepened slopes seem to be the main factors for the occurrence of sackungen. However, gradual loss of rock strength, groundwater fluctuations, subsidence due to evaporite dissolution and earthquake shaking, may contribute to their formation. For a better understanding of the origin of sackungen, chronological data are crucial. We used the cosmic ray exposure (CRE) dating method for deciphering the activity of the Arc and Rognier sackungen. This method allows quantification of the exposure duration of a surface to cosmic rays, by measuring the amount of accumulated cosmogenic nuclides in surficial rocks. Because sackung scarps usually form in hard rocks containing quartz, we used the <span class="hlt">10</span><span class="hlt">Be</span> cosmogenic nuclide which is produced in situ by spallation reactions on Si and O (<span class="hlt">36</span><span class="hlt">Cl</span> can be used for limestone). The measurements were performed at ASTER, the French accelerator mass spectrometry facility located at the CEREGE laboratory in Aix-en-Provence. The CRE dating method allows direct dating of most of the geomorphologic structures involved in sackungen: sackung fault scarps, rock slopes, debris slopes, screes, rock glaciers, glacier-polished rock surface</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Geomo.268..184H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Geomo.268..184H"><span id="translatedtitle">Global analysis of the stream power law parameters based on worldwide <span class="hlt">10</span><span class="hlt">Be</span> denudation rates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Harel, M.-A.; Mudd, S. M.; Attal, M.</p> <p>2016-09-01</p> <p>The stream power law, expressed as E = KAmSn - where E is erosion rate [LT - 1], K is an erodibility coefficient [T - 1L (1 - 2m)], A is drainage area [L 2], S is channel gradient [L/L], and m and n are constants - is the most widely used model for bedrock channel incision. Despite its simplicity and limitations, the model has proved useful for topographic evolution, knickpoint migration, palaeotopography reconstruction, and the determination of rock uplift patterns and rates. However, the unknown parameters K, m, and n are often fixed arbitrarily or are based on assumptions about the physics of the erosion processes that are not always valid, which considerably limits the use and interpretation of the model. In this study, we compile a unique global data set of published basin-averaged erosion rates that use detrital cosmogenic <span class="hlt">10</span><span class="hlt">Be</span>. These data (N = 1457) enable values for fundamental river properties to be empirically constrained, often for the first time, such as the concavity of the river profile (m/n ratio or concavity index), the link between channel slope and erosion rate (slope exponent n), and substrate erodibility (K). These three parameters are calculated for 59 geographic areas using the integral method of channel profile analysis and allow for a global scale analysis in terms of climatic, tectonic, and environmental settings. In order to compare multiple sites, we also normalize n and K using a reference concavity index m/n = 0.5. A multiple regression analysis demonstrates that intuitive or previously demonstrated local-scale trends, such as the correlation between K and precipitation rates, do not appear at a global scale. Our results suggest that the slope exponent is generally > 1, meaning that the relationship between erosion rate and the channel gradient is nonlinear and thus support the hypothesis that incision is a threshold controlled process. This result questions the validity of many regional interpretations of climate and/or tectonics where</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMPP13E..05C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMPP13E..05C"><span id="translatedtitle">Holocene Deglaciation of the Scandinavian Ice Sheet: Preliminary <span class="hlt">10</span><span class="hlt">Be</span> Ages</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cuzzone, J. K.; Clark, P. U.; Marcott, S. A.; Lunkka, J.; Wohlfarth, B.; Caffee, M. W.; Carlson, A. E.</p> <p>2013-12-01</p> <p>The response of ice sheets to a warming climate is not well understood. Because we are limited in our understanding of present dynamics, reconstructing the deglaciation of former ice sheets allows for a better understanding of how past ice sheets responded to a warming climate along with their contribution to sea-level rise. These reconstructions also serve as critical constraints for ice sheet modeling efforts. Here, we present a suite of new <span class="hlt">10</span><span class="hlt">Be</span> ages from erratic boulders along three transects spanning southern to northern Sweden and Finland, that improve our understanding of the deglaciation of the Scandinavian Ice Sheet (SIS) beginning ~ 11.7ka through its final demise during the early Holocene. Dates from southern Finland, beginning at the Salpausselka Younger Dryas moraine (11.5 × 0.7 ka, n=4), inland southern Finland near Jyvaskyla (11.5 × 0.5ka, n=2), and coastal Finland (~60km from Gulf of Bothnia) near Vimpeli (11.5 × 0.4ka, n=4) indicate a rapid retreat following the Younger Dryas for Southern Finland (~500km within uncertainty of ages). Preliminary dates also exist for Northern Finland, near Inari (10.8 × 0.5ka, n=4) and near Oulu (10.5 × 0.6 ka, n = 4) suggesting a later retreat in the north. Dates from southern Sweden, near Skovde (12.73 × 0.8ka, n=4) to Mora (10.41 × 0.6ka, n=5) suggest a slower retreat (over ~400km). Lastly, dates in Northwestern Sweden suggest a final termination of the SIS around 9.4 × 0.7ka (n = 3). Additional ages are now being processed at PRIME Lab, Purdue University, which will further strengthen our understanding of SIS retreat from all sampled sites. These new data will help to constrain the Holocene deglaciation of the SIS and its associated retreat rates, and establish the SIS contribution to Holocene sea level rise, which will improve our understanding of ice-sheet response to a warming climate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70030796','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70030796"><span id="translatedtitle">An episode of rapid bedrock channel incision during the last glacial cycle, measured with <span class="hlt">10</span><span class="hlt">Be</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Reusser, L.; Bierman, P.; Pavich, M.; Larsen, J.; Finkel, R.</p> <p>2006-01-01</p> <p>We use <span class="hlt">10</span><span class="hlt">Be</span> to infer when, how fast, and why the Susquehanna River incised through bedrock along the U.S. Atlantic seaboard, one of the world's most prominent and ancient passive margins. Although the rate at which large rivers incise rock is a fundamental control on the development of landscapes, relatively few studies have directly measured how quickly such incision occurs either in tectonically active environments or along passive margins. Exposure ages of fluvially carve d, bedrock strath terraces, preserved along the lower Susquehanna River, demonstrate that even along a passive margin, large rivers are capable of incising through rock for short periods of time at rates approaching those recorded in tectonically active regions, such as the Himalayas. Over eighty samples, collected along and between three prominent levels of strath terraces within Holtwood Gorge, indicate that the Susquehanna River incised more than 10 meters into the Appalachian Piedmont during the last glacial cycle. Beginning ???36 ka, incision rates increased dramatically, and remained elevated until ???14 ka. The northern half of the Susquehanna basin was glaciated during the late Wisconsinan; however, similar rates and timing of incision occurred in the unglaciated Potomac River basin immediately to the south. The concurrence of incision periods on both rivers suggests that glaciation and associated meltwater were not the primary drivers of incision. Instead, it appears that changing climatic conditions during the late Pleistocene promoted an increase in the frequency and magnitude of flood events capable of exceeding thresholds for rock detachment and bedrock erosion, thus enabling a short-lived episode of rapid incision into rock. Although this study has constraine d the timing and rate of bedrock incision along the largest river draining the Atlantic passive margin, the dates alone cannot explain fully why, or by what processes, this incision occurred. However, cosmogenic dating offers</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813561G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813561G"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> surface exposure dating reveals strong active deformation in the central Andean backarc interior</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>García Morabito, Ezequiel; Terrizzano, Carla; Zech, Roland; Willett, Sean; Yamin, Marcela; Haghipour, Negar; Wuethrich, Lorenz; Christl, Marcus; María Cortes, José; Ramos, Victor</p> <p>2016-04-01</p> <p>Understanding the deformation associated with active thrust wedges is essential to evaluate seismic hazard. How is active faulting distributed throughout the wedge, and how much deformation is taken up by individual structures? We address these questions for our study region, the central Andean backarc of Argentina. We combined a structural and geomorphological approach with surface exposure dating (<span class="hlt">10</span><span class="hlt">Be</span>) of alluvial fans and strath terraces in two key localities at ~32° S: the Cerro Salinas, located in the active orogenic front of the Precordillera, and the Barreal block in the interior of the Andean mountain range. We analysed 22 surface samples and 6 depth profiles. At the thrust front, the oldest terrace (T1) yields an age of 100-130 ka, the intermediate terrace (T2) between 40-95 ka, and the youngest terrace (T3) an age of ~20 ka. In the Andean interior, T1´ dates to 117-146 ka, T2´ to ~70 ka, and T3´ to ~20 ka, all calculations assuming negligible erosion and using the scaling scheme for spallation based on Lal 1991, Stone 2000. Vertical slip rates of fault offsets are 0.3-0.5 mm/yr and of 0.6-1.2 mm/yr at the thrust front and in the Andean interior, respectively. Our results highlight: i) fault activity related to the growth of the Andean orogenic wedge is not only limited to a narrow thrust front zone. Internal structures have been active during the last 150 ka, ii) deformation rates in the Andean interior are comparable or even higher that those estimated and reported along the emerging thrust front, iii) distribution of active faulting seems to account for unsteady state conditions, and iv) seismic hazards may be more relevant in the internal parts of the Andean orogen than assumed so far. References Lal, D., 1991: Cosmic ray labeling of erosion surfaces: In situ nuclide production rates and erosion models. Earth and Planetary Science Letters 104: 424-439. Stone, J.O., 2000: Air pressure and cosmogenic isotope production. Journal of Geophysical</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMPP11A2204M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMPP11A2204M"><span id="translatedtitle">The CREp program, a fully parameterizable program to compute exposure ages (3He, <span class="hlt">10</span><span class="hlt">Be</span>)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin, L.; Blard, P. H.; Lave, J.; Delunel, R.; Balco, G.</p> <p>2015-12-01</p> <p>Over the last decades, cosmogenic exposure dating permitted major advances in Earth surface sciences, and particularly in paleoclimatology. Yet, exposure age calculation is a dense procedure. It requires numerous choices of parameterization and the use of an appropriate production rate. Nowadays, Earth surface scientists may either calculate exposure ages on their own or use the available programs. However, these programs do not offer the possibility to include all the most recent advances in Cosmic Ray Exposure (CRE) dating. Notably, they do not propose the most recent production rate datasets and they only offer few possibilities to test the impact of the atmosphere model and the geomagnetic model on the computed ages. We present the CREp program, a Matlab © code that computes CRE ages for 3He and <span class="hlt">10</span><span class="hlt">Be</span> over the last 2 million years. The CREp program includes the scaling models of Lal-Stone in the "Lal modified" version (Balco et al., 2008; Lal, 1991; Stone, 2000) and the LSD model (Lifton et al., 2014). For any of these models, CREP allows choosing between the ERA-40 atmosphere model (Uppala et al., 2005) and the standard atmosphere (National Oceanic and Atmospheric Administration, 1976). Regarding the geomagnetic database, users can opt for one of the three proposed datasets: Muscheler et al. 2005, GLOPIS-75 (Laj et al. 2004) and the geomagnetic framework proposed in the LSD model (Lifton et al., 2014). They may also import their own geomagnetic database. Importantly, the reference production rate can be chosen among a large variety of possibilities. We made an effort to propose a wide and homogenous calibration database in order to promote the use of local calibration rates: CREp includes all the calibration data published until July 2015 and will be able to access an updated online database including all the newly published production rates. This is crucial for improving the ages accuracy. Users may also choose a global production rate or use their own data</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1412086B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1412086B"><span id="translatedtitle">Contrasting Modern and <span class="hlt">10</span><span class="hlt">Be</span>- derived erosion rates for the Southern Betic Cordillera, Spain</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bellin, N.; Vanacker, V.; Kubik, P.</p> <p>2012-04-01</p> <p>In Europe, Southeast Spain was identified as one of the regions with major treat of desertification in the context of future land use and climate change. During the last years, significant progress has been made to understand spatial patterns of modern erosion rates in these semi-arid degraded environments. Numerous European projects have contributed to the collection of modern erosion data at different spatial scales for Southeast Spain. However, these data are rarely analysed in the context of long-term changes in vegetation, climate and human occupation. In this paper, we present Modern and Holocene denudation rates for small river basins (1 to 10 km2) located in the Spanish Betic Cordillera. Long-term erosion data were derived from cosmogenic nuclide analyses of river-borne sediment. Modern erosion data were quantified through analysis of sediment deposition volumes behind check dams, and represent average erosion rates over the last 10 to 40 years. Modern erosion rates are surprisingly low (mean erosion rate = 0.048 mm y-1; n=36). They indicate that the steep, sparsely vegetated hillslopes in the Betic Cordillera cannot directly be associated with high erosion rates. <span class="hlt">10</span><span class="hlt">Be</span> -derived erosion rates integrate over the last 37500 to 3500 years, and are roughly of the same magnitude. They range from 0.013 to 0.243 mm y-1 (mean denudation rate = 0.062 mm y-1 ± 0.054; n=20). Our data suggest that the modern erosion rates are similar to the long-term erosion rates in this area. This result is in contrast with the numerous reports on human-accelerated modern erosion rates for Southeast Spain. Interestingly, our new data on long-term erosion rates show a clear spatial pattern, with higher erosion rates in the Sierra Cabrera and lower erosion rates in Sierra de las Estancias, and Sierra Torrecilla. Preliminary geomorphometric analyses suggest that the spatial variation that we observe in long-term erosion rates is related to the gradient in uplift rates of the Betic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EPJWC.11706011D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EPJWC.11706011D"><span id="translatedtitle">Study of cluster structures in <span class="hlt">10</span><span class="hlt">Be</span> and 16C neutron-rich nuclei via break-up reactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dell'Aquila, D.; Acosta, L.; Amorini, F.; Andolina, R.; Auditore, L.; Berceanu, I.; Cardella, G.; Chatterjiee, M. B.; De Filippo, E.; Francalanza, L.; Gnoffo, B.; Grzeszczuk, A.; Lanzalone, G.; Lombardo, I.; Martorana, N.; Minniti, T.; Pagano, A.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Pop, A.; Porto, F.; Quattrocchi, L.; Rizzo, F.; Rosato, E.; Russotto, P.; Trifirò, A.; Trimarchi, M.; Verde, G.; Vigilante, M.</p> <p>2016-05-01</p> <p>Projectile break-up reactions induced on polyethylene (CH2) target are used in order to study the spectroscopy of <span class="hlt">10</span><span class="hlt">Be</span> and 16C nuclei. For the present experiment we used <span class="hlt">10</span><span class="hlt">Be</span> and 16C beams delivered by the FRIBs facility at INFN-LNS, and the CHIMERA 4π multi-detector. <span class="hlt">10</span><span class="hlt">Be</span> and 16C structures are studied via a relative energy analysis of break-up fragments. The 4He+6He break-up channel allowed us to study the spectroscopy of <span class="hlt">10</span><span class="hlt">Be</span>; in particular we find evidence of a new state in <span class="hlt">10</span><span class="hlt">Be</span> at 13.5 MeV excitation energy. The 16C nucleus is studied via 6He-<span class="hlt">10</span><span class="hlt">Be</span> correlation; we find the fingerprint of a possible state at about 20.6 MeV</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26PSL.439..143C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26PSL.439..143C"><span id="translatedtitle">Simulating the mobility of meteoric <span class="hlt">10</span><span class="hlt">Be</span> in the landscape through a coupled soil-hillslope model (Be2D)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Campforts, Benjamin; Vanacker, Veerle; Vanderborght, Jan; Baken, Stijn; Smolders, Erik; Govers, Gerard</p> <p>2016-04-01</p> <p>Meteoric <span class="hlt">10</span><span class="hlt">Be</span> allows for the quantification of vertical and lateral soil fluxes over long time scales (103-105 yr). However, the mobility of meteoric <span class="hlt">10</span><span class="hlt">Be</span> in the soil system makes a translation of meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories into erosion and deposition rates complex. Here, we present a spatially explicit 2D model simulating the behaviour of meteoric <span class="hlt">10</span><span class="hlt">Be</span> on a hillslope. The model consists of two parts. The first component deals with advective and diffusive mobility of meteoric <span class="hlt">10</span><span class="hlt">Be</span> within the soil profile, and the second component describes lateral soil and meteoric <span class="hlt">10</span><span class="hlt">Be</span> fluxes over the hillslope. Soil depth is calculated dynamically, accounting for soil production through weathering as well as downslope fluxes of soil due to creep, water and tillage erosion. Synthetic model simulations show that meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories can be related to erosion and deposition across a wide range of geomorphological and pedological settings. Our results also show that meteoric <span class="hlt">10</span><span class="hlt">Be</span> can be used as a tracer to detect human impact on soil fluxes for soils with a high affinity for meteoric <span class="hlt">10</span><span class="hlt">Be</span>. However, the quantification of vertical mobility is essential for a correct interpretation of the observed variations in meteoric <span class="hlt">10</span><span class="hlt">Be</span> profiles and inventories. Application of the Be2D model to natural conditions using data sets from the Southern Piedmont (Bacon et al., 2012) and Appalachian Mountains (Jungers et al., 2009; West et al., 2013) allows to reliably constrain parameter values. Good agreement between simulated and observed meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations and inventories is obtained with realistic parameter values. Furthermore, our results provide detailed insights into the processes redistributing meteoric <span class="hlt">10</span><span class="hlt">Be</span> at the soil-hillslope scale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26PSL.437...47I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26PSL.437...47I"><span id="translatedtitle">A continuous ice-core <span class="hlt">10</span><span class="hlt">Be</span> record from Mongolian mid-latitudes: Influences of solar variability and local climate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Inceoglu, F.; Knudsen, M. F.; Olsen, J.; Karoff, C.; Herren, P.-A.; Schwikowski, M.; Aldahan, A.; Possnert, G.</p> <p>2016-03-01</p> <p>High-resolution <span class="hlt">10</span><span class="hlt">Be</span> records used for studies of detailed changes in atmospheric <span class="hlt">10</span><span class="hlt">Be</span> production rates predominantly derive from polar ice cores. In this study, we present the first <span class="hlt">10</span><span class="hlt">Be</span> record from a mid-latitude ice core. The ice core derives from the Tsambagarav mountain range located in the Mongolian Altai region. The new <span class="hlt">10</span><span class="hlt">Be</span> concentration record spans the period from AD 1550 to 2009, while the flux record extends from AD 1816 to 2009. The <span class="hlt">10</span><span class="hlt">Be</span> concentration in the Tsambagarav ice core ranges between ∼ 1.5 ×104 and ∼ 10 ×104 atomsg-1, whereas the <span class="hlt">10</span><span class="hlt">Be</span> flux changes from ∼0.02 to ∼0.15 atoms cm-2 s-1. The average <span class="hlt">10</span><span class="hlt">Be</span> flux at Tsambagarav is four times higher than the average <span class="hlt">10</span><span class="hlt">Be</span> flux recorded in the NGRIP and Dome Fuji ice cores, which is in accordance with model predictions. In general, the long-term trends observed in the Tsambagarav <span class="hlt">10</span><span class="hlt">Be</span> concentration and flux records are reasonably similar to those observed in the NGRIP ice core. A comparison between the Tsambagarav <span class="hlt">10</span><span class="hlt">Be</span> record, group sunspot numbers (GSNs), and solar modulation potentials based on 14C in tree rings suggests that the Maunder Minimum was associated with a prolonged maximum in <span class="hlt">10</span><span class="hlt">Be</span> concentrations at Tsambagarav, whereas the Dalton Minimum was associated with a minor increase in the <span class="hlt">10</span><span class="hlt">Be</span> concentration and flux that was delayed relative to the primary minimum in GSNs. The sulphate record from Tsambagarav shows that large positive anomalies in the sulphate concentration are associated with negative anomalies in the <span class="hlt">10</span><span class="hlt">Be</span> concentration. A concurrent positive sulphate anomaly may explain why the main phase of the Dalton Minimum is subdued in the <span class="hlt">10</span><span class="hlt">Be</span> record from Tsambagarav. Spectral analysis indicates that the 11-yr solar-cycle signal may have influenced the new <span class="hlt">10</span><span class="hlt">Be</span> record, but the evidence supporting a direct link is ambiguous. Local and regional climatic changes, such as cyclonic versus anticyclonic conditions and related storm tracks, most likely played a significant role for the <span class="hlt">10</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26PSL.440..105H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26PSL.440..105H"><span id="translatedtitle">Multiple <span class="hlt">10</span><span class="hlt">Be</span> records revealing the history of cosmic-ray variations across the Iceland Basin excursion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Horiuchi, Kazuho; Kamata, Kanae; Maejima, Shun; Sasaki, Sho; Sasaki, Nobuyoshi; Yamazaki, Toshitsugu; Fujita, Shuji; Motoyama, Hideaki; Matsuzaki, Hiroyuki</p> <p>2016-04-01</p> <p>Cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> is a proxy of cosmic-ray flux, and its natural records provide vital information about the past intensity variability of the geomagnetic field and solar activity. <span class="hlt">10</span><span class="hlt">Be</span> records also serve as powerful tools for global synchronization among a variety of paleoarchives and for elucidating sedimentary processes on natural remanent magnetization acquisition. However, high-resolution (multi-decadal to multi-centennial) records of <span class="hlt">10</span><span class="hlt">Be</span> are scarce, especially those older than several tens of thousands of years. Here we present multiple high-resolution <span class="hlt">10</span><span class="hlt">Be</span> records of the Iceland Basin geomagnetic excursion interval (ca. 170-200 kyr ago) obtained from sediment cores (authigenic <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio) and an ice core (atmospheric <span class="hlt">10</span><span class="hlt">Be</span> flux). Comparing sedimentary <span class="hlt">10</span><span class="hlt">Be</span> records with relative paleointensity from the same cores, we found differences in the magnetic lock-in depth, even between adjacent cores. The <span class="hlt">10</span><span class="hlt">Be</span>-proxy records from the sediment and ice cores exhibit common characteristics: an asymmetric large-scale variation, a ∼7-kyr quasi-plateau around the maximum with a characteristic mid-term depression, and multi-millennial fluctuations in cosmic-ray flux during this interval. Minimal-synchronized and stacked <span class="hlt">10</span><span class="hlt">Be</span> records show that maximum cosmic-ray flux occurred 188.5-190.0 kyr ago and was double the present flux. A wavelet analysis of the stacked curve reveals dominant 4-kyr and secondary 8-kyr periodicities, both of which can be interpreted as intrinsic geomagnetic cycles. The wavelet spectrum of the high-resolution ice-core record shows a periodicity of 1.7 kyr and somewhat intermingled multi-centennial cycles around the maxima of <span class="hlt">10</span><span class="hlt">Be</span>, which likely represent solar cycles in this period. High-resolution <span class="hlt">10</span><span class="hlt">Be</span> records from multiple paleoarchives provide both a robust proxy record of cosmic-ray flux and a valuable tool for detailed global synchronization based on cosmic-ray variations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016LPICo1921.6222D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LPICo1921.6222D"><span id="translatedtitle">Beryllium-Boron Systematics of Refractory Inclusions in CR2 and CV3 Chondrites: Evidence for <span class="hlt">10</span><span class="hlt">Be</span> Heterogeneity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dunham, E.; Wadhwa, M.; Simon, S.; Grossman, L.</p> <p>2016-08-01</p> <p>Be-B systematics of Allende (CV3), Axtell (CV3), and NWA 5028 (CR2) CAIs suggests that <span class="hlt">10</span><span class="hlt">Be</span> was distributed heterogeneously in the early solar system which implies that <span class="hlt">10</span><span class="hlt">Be</span> was produced in the solar nebula by irradiation of nebular gas or dust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMEP51B0598J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMEP51B0598J"><span id="translatedtitle">In Situ-produced vs. Meteoric <span class="hlt">10</span><span class="hlt">Be</span> in Hillslope Soils: One Isotope, Two Tracers, Different Stories</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jungers, M. C.; Bierman, P. R.; Matmon, A.; Cox, R.; Pavich, M.; Finkel, R. C.</p> <p>2009-12-01</p> <p>In situ-produced and meteoric <span class="hlt">10</span><span class="hlt">Be</span> are both powerful tools for tracing the production and transport of hillslope sediment. In situ-produced <span class="hlt">10</span><span class="hlt">Be</span> is used to infer sediment production rates as well as investigate sediment sources and transport. Meteoric <span class="hlt">10</span><span class="hlt">Be</span> may also be useful for inferring sediment production and transport rates in some landscapes, especially those that lack the target minerals for in situ-produced <span class="hlt">10</span><span class="hlt">Be</span>. Few studies have investigated the insights gained by a comparing in situ-produced and meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories. We present a series of paired <span class="hlt">10</span><span class="hlt">Be</span> inventories from different climatic and tectonic regimes to illustrate both the value and the potential pitfalls of coupling these geomorphic tracers. The mean in situ and meteoric <span class="hlt">10</span><span class="hlt">Be</span> near surface (within a meter) inventories for our field areas are as follows: Great Smoky Mountains, NC, USA: 3.6 x 107 atoms cm-2 and 3.3 x 1010 atoms cm-2; Laurely Fork, PA, USA: 2.6 x 106 atoms cm-2 and 3.0 x 109 atoms cm-2; Oregon Coast Range, OR, USA: no in situ data and 3.87 x 1010 atoms cm-2; North Island, New Zealand: no in situ data and 1.8 x 109 atoms cm-2; and Amparafaravola, Madagascar: 1.86 x 107 atoms cm-2 and 8.0 x 109 atoms cm-2. The associated inferred soil residence times, respectively, are: Great Smoky Mountains, NC, USA: 40.9 ky and 25.6 ky; Laurely Fork, PA, USA: 2.9 ky and 2.3 ky; Oregon Coast Range, OR, USA: n/a and 30ky; North Island, New Zealand: n/a and 1.5 ky; and Amparafaravola, Madagascar: 21 ky and 6.2 ky. Soil residence times inferred from meteoric <span class="hlt">10</span><span class="hlt">Be</span> assume a global average delivery rate of 1.3 x 106 atoms cm-2 yr-1. These soil residence times are minimum values that assume that all in situ and meteoric <span class="hlt">10</span><span class="hlt">Be</span> is accounted for. Discrepancies between inferred soil residence times most likely highlight some error in assumptions regarding meteoric <span class="hlt">10</span><span class="hlt">Be</span> retention in the soil mantles that we sampled. For example, if meteoric <span class="hlt">10</span><span class="hlt">Be</span> is not retained at the near surface where we collected our samples</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.T13C3027F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.T13C3027F"><span id="translatedtitle">A Model for Interpreting <span class="hlt">10</span><span class="hlt">Be</span> Basin-Wide Erosion Rates in Post-Glacial Environments, Northwest Scotland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fame, M. L.; Owen, L. A.; Balco, G.; Spotila, J. A.</p> <p>2015-12-01</p> <p>Meaningful interpretation of in-situ cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> basin-wide erosion rates in slowly eroding postglacial catchments is complicated because <span class="hlt">10</span><span class="hlt">Be</span> is inherited through shifts between glacial and fluvial regimes and ice shielding prevents <span class="hlt">10</span><span class="hlt">Be</span> production. Such environments do not attain isotopic and landscape steady state, conditions necessary for the current method of calculating basin-wide erosion rates. We propose an alternate set of assumptions, specific to postglacial regions, which make it possible to calculate basin-wide erosion rates in the post-glacial Highlands of NW Scotland. From 20 Scottish basins basin-wide <span class="hlt">10</span><span class="hlt">Be</span> concentrations range from 2.129 x 104 to 4.870 x 104 atoms/g qtz. Average <span class="hlt">10</span><span class="hlt">Be</span> concentrations from shallow till and bank deposits within the basins are 2.856 x 104 atoms/g qtz, similar to the basin-wide concentrations, whereas average bedrock concentrations in the basins are 1.747 x 105 atoms/g qtz. This suggests that during the postglacial time most active sediment is derived from reworked deposits rather then sub-aerially eroded bedrock. Therefore, we make the simplifying assumption that most bedrock erosion occurs during glaciation. A deeply buried till that has experienced no nuclide production since deglaciation has a <span class="hlt">10</span><span class="hlt">Be</span> concentration of 6.810 x 103 atoms/g qtz and allows us to estimate how much of the <span class="hlt">10</span><span class="hlt">Be</span> in basin-wide samples was produced since deglaciation. A glacial ice thickness of only 2 m would shield all <span class="hlt">10</span><span class="hlt">Be</span> production; therefore we assume that no <span class="hlt">10</span><span class="hlt">Be</span> production occurred during glacial periods and that all production occurs during interglacial periods. Using 100 ka as the approximate duration of a Pleistocene glacial-interglacial cycle, comprised of a 15 ka interglacial period and an 85 ka glacial period, and the aforementioned assumptions we have derived a numerical model to calculate basin-wide glacial erosion rates in NW Scotland.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.9314M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9314M"><span id="translatedtitle">Cosmogenic Nuclides <span class="hlt">10</span><span class="hlt">Be</span>-21Ne Burial Dating of Middle Miocene Sedimentary Formation of the Hongliu Valley in Southern Ningxia Basin: A Case of Isotopic Geochronology Study for the Cenozoic Sedimentary Strata</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ma, Yan; Zhang, Huiping; Wang, Weitao; Pang, Jianzhang; Zheng, Dewen</p> <p>2016-04-01</p> <p>Chronology studies for the Cenozoic sedimentary strata based on the magnetostratigraphy cannot afford the unique chronological sequences in the absence of absolute ages from biostratigraphy or volcanic ash chronology. In situ-produced cosmogenic nuclides provide a powerful tool for the sediment dating based on the time-dependent concentration ratio of two nuclides, which are produced in the same mineral but with different half-lives. Thereinto,<span class="hlt">10</span><span class="hlt">Be</span>-<span class="hlt">26</span><span class="hlt">Al</span> is the most widely used nuclide pairs, of which the available dating range spans the Plio-Pleistocene. But the coupling of <span class="hlt">10</span><span class="hlt">Be</span> with the stable nuclide 21Ne would significantly improve the burial dating range up to the middle Miocene, which is promising in revolutionizing the chronology study for the Late Cenozoic terrestrial sedimentary sequences. We have applied <span class="hlt">10</span><span class="hlt">Be</span>-21Ne pair for dating the middle Miocene sediments of the Hongliu Valley in southern Ningxia basin. Two major features of the sediments are involved in our study: (1) sediments originated from the steady erosion of the source area, and (2) the burial depth of our sample after deposition is time dependent due to the gradual accumulation of sediments into basin. The post-burial nuclide production is estimated to be less than 3%, including the contribution by muon interactions, of the total nuclide concentrations measured in our sample. Our <span class="hlt">10</span><span class="hlt">Be</span>-21Ne analysis demonstrates the age of the burial sample is 12.4(+0.6/-0.4) Ma, and the erosion rate at the source area is 0.26±0.01 cm ka-1. The sample's burial age is consistent with the age constraint set by the Hongliugou Formation (16.7-5.4 Ma) which we collected the sample in. Vertebrate fossils of Platybelodon tongxinensis with an age between 12 and 15 Ma exhumated along with our sample further verifies the reliability of our dating results for the middle Miocene sediments.This study has shown the improved age range of cosmogenic-nuclide burial dating method by incorporating the stable nuclide 21Ne, and has</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70019580','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70019580"><span id="translatedtitle">Beryllium geochemistry in soils: Evaluation of <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios in authigenic minerals as a basis for age models</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Barg, E.; Lal, D.; Pavich, M.J.; Caffee, M.W.; Southon, J.R.</p> <p>1997-01-01</p> <p>Soils contain a diverse and complex set of chemicals and minerals. Being an 'open system', both in the chemical and nuclear sense, soils have defied quantitative nuclear dating. However, based on the published studies of the cosmogenic atmospheric <span class="hlt">10</span><span class="hlt">Be</span> in soils, its relatively long half-life (1.5 Ma), and the fact that <span class="hlt">10</span><span class="hlt">Be</span> gets quickly incorporated in most soil minerals, this radionuclide appears to be potentially the most useful for soil dating. We therefore studied the natural variations in the specific activities of <span class="hlt">10</span><span class="hlt">Be</span> with respect to the isotope 9Be in mineral phases in eight profiles of diverse soils from temperate to tropical climatic regimes and evaluated the implications of the data for determining the time of formation of soil minerals, following an earlier suggestion [Lal et al., 1991. Development of cosmogenic nuclear methods for the study of soil erosion and formation rates. Current Sci. 61, 636-639.]. We find that the <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios in both bulk soils and in the authigenic mineral phases are confined within a narrower range than in <span class="hlt">10</span><span class="hlt">Be</span> concentrations. Also, the highest <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios in authigenic minerals are observed at the soil-rock interface as predicted by the model. We present model <span class="hlt">10</span><span class="hlt">Be</span>/9Be ages of the B-horizon and the corresponding soil formation rates for several soil profiles. The present study demonstrates that the <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios in the authigenic phases, e.g. clay and Fe-hydroxides, can indeed be used for obtaining useful model ages for soils younger than 10-15 Ma. However, the present work has to be pushed considerably further, to take into account more realistic age models in which, for instance, downward transport of <span class="hlt">10</span><span class="hlt">Be</span> and clays, and in-situ dissolution of clay minerals at depths, altering the <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios of the acidic solutions, are included. We show that in the case of younger soils (< 1 Ma) studied here, their <span class="hlt">10</span><span class="hlt">Be</span> inventories and <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios have been significantly disturbed possibly by mixing with transported</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.6472B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.6472B"><span id="translatedtitle">New ways of using an old isotopic system - meteoric <span class="hlt">10</span>-<span class="hlt">Be</span> is back and ready to do geomorphology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bierman, P.; Reusser, L.; Pavich, M.</p> <p>2009-04-01</p> <p>Meteoric <span class="hlt">10</span>-<span class="hlt">Be</span>, produced in the atmosphere and delivered in precipitation, is an important tracer of sediment and geomorphic processes. This talk will review several decades of work measuring <span class="hlt">10</span>-<span class="hlt">Be</span> adhered to soil and sediment collected from varied terrains around the world. We will then present new data and modeling approaches demonstrating the rich potential but complex, dynamic nature of this isotope system. Considering all of these data, we will examine the utility of meteoric<span class="hlt">10</span>-<span class="hlt">Be</span>, produced in the atmosphere and delivered in precipitation, as a tracer of watershed and hillslope sediment transport processes at a variety of spatial scales. We will finish the talk by examining uncertainties that require additional research to resolve. After a brief hay-day in the 1980s, tracing sediment down rivers, dating a few terraces, and following sediment through subduction zones, meteoric or garden variety <span class="hlt">10</span>-<span class="hlt">Be</span> was largely forgotten. It's been lurking somewhere in the dark corners of isotope geoscience while its more famous but difficult-to-measure twin, the <span class="hlt">10</span>-<span class="hlt">Be</span> produced in quartz, got all the attention. Recently, several research groups have again begun to build upon the excellent foundation constructed by those working in the 1980s and early 1990s. New data from a series of soil pits on hillslopes from around the world suggest that meteoric <span class="hlt">10</span>-<span class="hlt">Be</span> is mobile in the soil column moving from the more acidic, organic-rich A-horizon to the B-horizon. Meteoric <span class="hlt">10</span>-<span class="hlt">Be</span> concentrations are well correlated with both soil pH and extractable Al suggesting that Be is retained in Al-rich grain coatings that we know, from numerous attempts to purify riverine quartz, survive fluvial transport all too well. The important take-away message is that meteoric <span class="hlt">10</span>-<span class="hlt">Be</span> is mobile in soil fluids while in situ <span class="hlt">10</span>-<span class="hlt">Be</span> only moves with the quartz grains in which it resides. Depth profiles of in situ and meteoric <span class="hlt">10</span>-<span class="hlt">Be</span> can be quite different, helping us to learn about rates of soil stirring and <span class="hlt">10</span>-<span class="hlt">Be</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.T31F2576R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.T31F2576R"><span id="translatedtitle">Using meteoric <span class="hlt">10</span><span class="hlt">Be</span> to constrain the age and structure of the frontal wedge at the Japan Trench</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Regalla, C.; Bierman, P. R.; Rood, D.; Motoyama, I.; Fisher, D. M.</p> <p>2013-12-01</p> <p>We present new meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentration data from marine sediments recovered during International Ocean Drilling Program (IODP) Exp. 343 that help constrain the age and internal structure of the frontal prism at the Japan trench in the vicinity of the 2011 Tohoku-oki M9 earthquake rupture. Exp. 343 recovered sediments from an ~200 m interval of the frontal wedge at site C0019. Core and log observations identify the plate boundary décollement at ~820 mbsf, which separates a deformed sedimentary wedge from relatively undeformed underthrust sediments. However, reconstructions of the structural evolution of the wedge are difficult because of similarity in lithology between sediments from the incoming and overriding plate, and the chaotic character of seismic reflectors in the frontal wedge. We utilize the radiogenic decay of <span class="hlt">10</span><span class="hlt">Be</span> (t1/2 =1.36 Ma) in marine sediments to constrain variations in sediment age with depth in core C0019. Meteoric <span class="hlt">10</span><span class="hlt">Be</span> was isolated from marine sediments at the University of Vermont using total fusion and <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios were measured at the Scottish Universities Environmental Research Centre. Concentrations of meteoric <span class="hlt">10</span><span class="hlt">Be</span> in core C0019 range from 1.7x107 to 2.1x109 atm/g and are consistent with <span class="hlt">10</span><span class="hlt">Be</span> concentrations at nearby DSDP sites 436 and 434. We calculate <span class="hlt">10</span><span class="hlt">Be</span> sediment ages for analyzed samples assuming a range of initial <span class="hlt">10</span><span class="hlt">Be</span> concentrations from 1.6 to 2.1x109 atm/g. These concentrations are constrained by a <span class="hlt">10</span><span class="hlt">Be</span> sample co-located with a radiolarian micropaleontology sample at 780 mbsf that yields a Quaternary age, and from previously reported <span class="hlt">10</span><span class="hlt">Be</span> concentrations for Quaternary sediments in nearby DSDP cores. <span class="hlt">10</span><span class="hlt">Be</span> and radiolarian micropaleontology samples from similar depths yield consistent ages for late Miocene to Quaternary sediments (R2 = 0.89). Calculated <span class="hlt">10</span><span class="hlt">Be</span> ages range from 0-10 Ma, with ~50% of analyzed samples yielding ages <2 Ma. Repetition and inversion of high (109 atm/g) and low (107 atm/g) concentration sediments with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMPP11D1456G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMPP11D1456G"><span id="translatedtitle">Long-term erosion and interglacial period exposure in Western Greenland from meteoric <span class="hlt">10</span><span class="hlt">Be</span> in ice-bound sediment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Graly, J. A.; Corbett, L.; Bierman, P. R.; Neumann, T.; Rood, D. H.; Finkel, R. C.</p> <p>2010-12-01</p> <p>To examine the history of surface exposure and erosion in areas of Western Greenland presently covered by ice, we measured the concentration of meteoric <span class="hlt">10</span><span class="hlt">Be</span> in ice-bound fine sediment at three locations: Kangerlussuaq (67.1°N), Ilulissat (69.4°N), and Upernavik (72.5°N). Meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations at Ilulissat and Upernavik range from 2×106 to 2×108 atoms/g and are statistically indistinguishable from each other. Meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations at Kangerlussuaq range from 2×106 to 5×107 atoms/g and are significantly lower than the values found at the northern two sites. Through comparison to typical meteoric <span class="hlt">10</span><span class="hlt">Be</span> distribution in soils, source soil ages can be estimated at each of these locations. These estimates suggest on the order of 105 years of exposure at the northern sites and on the order of 104 years of exposure at Kangerlussuaq. Because meteoric <span class="hlt">10</span><span class="hlt">Be</span> is lost from the soil system both by erosion and isotope decay, these exposure ages represent a minimum length of cumulative interglacial exposure. This exposure signal likely developed over several Late Pliocene and Pleistocene interglacial periods and prior to the onset of Northern hemisphere glaciation, ~2.7 Ma before present. To further constrain the glacial history of Western Greenland implied from the meteoric <span class="hlt">10</span><span class="hlt">Be</span> data, we constructed forward models of interglacial period exposure and glacial period erosion. The high levels of meteoric <span class="hlt">10</span><span class="hlt">Be</span> at Upernavik and Ilulissat imply erosion rates below 5 m/My and some preservation of pre-glacial regolith. The lower levels of meteoric <span class="hlt">10</span><span class="hlt">Be</span> at Kangerlussuaq can be explained with erosion rates as high as 20 m/My. Because of the substantial debris fluxes in modern Kangerlussuaq glaciers [Knight, et al., 2002], erosion rates greater than 10 m/My are likely. Meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories at Kangerlussuaq under 10-20 m/My of long-term erosion imply substantial interglacial exposure and the slow evacuation of sediment by glacial transport. These results suggest that</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004JQS....19..431K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004JQS....19..431K"><span id="translatedtitle">Surface exposure dating of the Great Aletsch Glacier Egesen moraine system, western Swiss Alps, using the cosmogenic nuclide <span class="hlt">10</span><span class="hlt">Be</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kelly, Meredith A.; Kubik, Peter W.; von Blanckenburg, Friedhelm; Schlüchter, Christian</p> <p>2004-07-01</p> <p>Egesen moraines throughout the Alps mark a glacial advance that has been correlated with the Younger Dryas cold period. Using the surface exposure dating method, in particular the measurement of the cosmogenic nuclide <span class="hlt">10</span><span class="hlt">Be</span> in rock surfaces, we attained four ages for boulders on a prominent Egesen moraine of Great Aletsch Glacier, in the western Swiss Alps. The <span class="hlt">10</span><span class="hlt">Be</span> dates range from 10 460+/-1100 to 9040+/-1020 yr ago. Three <span class="hlt">10</span><span class="hlt">Be</span> dates between 9630+/-810 and 9040+/-1020 yr ago are based upon samples from the surfaces of granite boulders. Two <span class="hlt">10</span><span class="hlt">Be</span> dates, 10 460+/-1100 and 9910+/-970 yr ago, are based upon a sample from a quartz vein at the surface of a schist boulder. In consideration of the numerous factors that can influence apparently young <span class="hlt">10</span><span class="hlt">Be</span> dates and the scatter within the data, we interpret the weighted mean of four boulder ages, 9640+/-430 yr (including the weighted mean of two <span class="hlt">10</span><span class="hlt">Be</span> dates of the quartz vein), as a minimum age of deposition of the moraine.<TR><TD>All <span class="hlt">10</span><span class="hlt">Be</span> dates from the Great Aletsch Glacier Egesen moraine are consistent with radiocarbon dates of nearby bog-bottom organic sediments, which provide minimum ages of deglaciation from the moraine. The <span class="hlt">10</span><span class="hlt">Be</span> dates from boulders on the Great Aletsch Glacier Egesen moraine also are similar to <span class="hlt">10</span><span class="hlt">Be</span> dates from Egesen moraines of Vadret Lagrev Glacier on Julier Pass, in the eastern Swiss Alps. Both the morphology of the Great Aletsch Glacier Egesen moraine and the comparison with <span class="hlt">10</span><span class="hlt">Be</span> dates from the inner Vadret Lagrev Egesen moraine support the hypothesis that the climatic cooling that occurred during the Younger Dryas cold episode influenced the glacial advance that deposited the Great Aletsch Glacier Egesen moraine. Because of the large size and slow response time of Great Aletsch Glacier, we suggest that the Great Aletsch Glacier Egesen moraine was formed during the last glacial advance of the multiphased Egesen cold period, the Kromer stage, during the Preboreal chron. Copyright</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRF..118.1877W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRF..118.1877W"><span id="translatedtitle">Regolith production and transport at the Susquehanna Shale Hills Critical Zone Observatory, Part 2: Insights from meteoric <span class="hlt">10</span><span class="hlt">Be</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>West, Nicole; Kirby, Eric; Bierman, Paul; Slingerland, Rudy; Ma, Lin; Rood, Dylan; Brantley, Susan</p> <p>2013-09-01</p> <p>Regolith-mantled hillslopes are ubiquitous features of most temperate landscapes, and their morphology reflects the climatically, biologically, and tectonically mediated interplay between regolith production and downslope transport. Despite intensive research, few studies have quantified both of these mass fluxes in the same field site. Here we present an analysis of 87 meteoric <span class="hlt">10</span><span class="hlt">Be</span> measurements from regolith and bedrock within the Susquehanna Shale Hills Critical Zone Observatory (SSHO), in central Pennsylvania. Meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations in bulk regolith samples (n = 73) decrease with regolith depth. Comparison of hillslope meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories with analyses of rock chip samples (n = 14) from a 24 m bedrock core confirms that >80% of the total inventory is retained in the regolith. The systematic downslope increase of meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories observed at SSHO is consistent with <span class="hlt">10</span><span class="hlt">Be</span> accumulation in slowly creeping regolith (~ 0.2 cm yr-1). Regolith flux inferred from meteoric <span class="hlt">10</span><span class="hlt">Be</span> varies linearly with topographic gradient (determined from high-resolution light detection and ranging-based topography) along the upper portions of hillslopes at SSHO. However, regolith flux appears to depend on the product of gradient and regolith depth where regolith is thick, near the base of hillslopes. Meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories at the north and south ridgetops indicate minimum regolith residence times of 10.5 ± 3.7 and 9.1 ± 2.9 ky, respectively, similar to residence times inferred from U-series isotopes in Ma et al. (2013). The combination of our results with U-series-derived regolith production rates implies that regolith production and erosion rates are similar to within a factor of two on SSHO hillcrests.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DNP.FE005K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DNP.FE005K"><span id="translatedtitle">Studying <span class="hlt">10</span><span class="hlt">Be</span> and 11Be Halo States through the (p,d) Single-Neutron Transfer Reaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuhn, Keri; Sarazin, Fred; (Pcb)<Sup>2</Sup> Collaboration; Tigress Collaboration</p> <p>2015-10-01</p> <p>One-neutron transfer reactions are being used to study single-particle neutron states in nuclei. For one-neutron halo nuclei, such as 11Be, the (p,d) reaction enables the removal of the halo neutron or of one of the core neutrons. This way, it is possible to simultaneously study the halo wavefunction of the 11Be ground-state but also a possible excited halo state in <span class="hlt">10</span><span class="hlt">Be</span>. The 11Be(p, d)<span class="hlt">10</span><span class="hlt">Be</span> transfer reaction at 10 MeV/nucleon is being investigated at the TRIUMF-ISAC II facility with the Printed Circuit Board Based Charged Particle ((PCB)2) array inside the TRIUMF ISAC Gamma-Ray Escape-Suppressed Spectrometer (TIGRESS). The ground state and first excited state of <span class="hlt">10</span><span class="hlt">Be</span> can be directly identified using deuteron identification and kinematics from the charged particle array, while the four excited states in<span class="hlt">10</span><span class="hlt">Be</span> around 6 MeV, including the suspected halo state (2- state), are identified using coincident gamma rays from TIGRESS with the identified deuterons. Angular distributions for the <span class="hlt">10</span><span class="hlt">Be</span> populated states will be shown along with their FRESCO fits. This work is partially supported by the US Department of Energy through Grant/Contract No. DE-FG03-93ER40789 (Colorado School of Mines).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvC..93b4611D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvC..93b4611D"><span id="translatedtitle">New experimental investigation of the structure of <span class="hlt">10</span><span class="hlt">Be</span> and 16C by means of intermediate-energy sequential breakup</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dell'Aquila, D.; Lombardo, I.; Acosta, L.; Andolina, R.; Auditore, L.; Cardella, G.; Chatterjiee, M. B.; De Filippo, E.; Francalanza, L.; Gnoffo, B.; Lanzalone, G.; Pagano, A.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Porto, F.; Quattrocchi, L.; Rizzo, F.; Rosato, E.; Russotto, P.; Trifirò, A.; Trimarchi, M.; Verde, G.; Vigilante, M.</p> <p>2016-02-01</p> <p><span class="hlt">10</span><span class="hlt">Be</span> and 16C spectroscopy has been investigated by analyzing their breakup events on CH2 and CD2 targets. Breakup fragments have been detected by means of the CHIMERA detector. In particular, we investigated cluster decays of <span class="hlt">10</span><span class="hlt">Be</span> in 4He+6He and of 16C in 6He+<span class="hlt">10</span><span class="hlt">Be</span> and 4He+6He+6He . From the relative energy analysis of breakup fragments, we investigate the spectroscopy of excited states of projectile nuclei. In the <span class="hlt">10</span><span class="hlt">Be</span> case we observe known states at 9.51, 10.16, 10.6, and 11.8 MeV. Further, we suggest the existence of a new state at 13.5 MeV, possibly 6+ as indicated from angular correlation analysis. The relative energy (Erel+Eth) spectrum of 16C, reconstructed starting from 6He+<span class="hlt">10</span><span class="hlt">Be</span> correlations, shows a peak at about 20.6 MeV, probably related to the existence of an high-lying excited state. Non-vanishing yields are also seen in the triple coincidences 4He+6He+6He .</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001M%26PS...36..301W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001M%26PS...36..301W"><span id="translatedtitle">Cosmic-ray exposure history of two Frontier Mountain H-chondrite showers from spallation and neutron-capture products</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Welten, K. C.; Nishiizumi, K.; Masarik, J.; Caffee, M. W.; Jull, A. J. T.; Klandrud, S. E.; Wieler, R.</p> <p>2001-02-01</p> <p>We measured the concentrations of <span class="hlt">10</span><span class="hlt">Be</span>, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, 41Ca and 14C in the metal and/or stone fractions of 27 Antarctic chondrites from Frontier Mountain (FRO), including two large H-chondrite showers. To estimate the pre-atmospheric size of the two showers, we determined the contribution of neutron-capture produced <span class="hlt">36</span><span class="hlt">Cl</span> (half-life = 3.01 ´ 105 years) and 41Ca (1.04 ´ 105 years) in the stone fraction. The measured activities of neutron-capture <span class="hlt">36</span><span class="hlt">Cl</span> and 41Ca, as well as spallation produced <span class="hlt">10</span><span class="hlt">Be</span> and <span class="hlt">26</span><span class="hlt">Al</span>, were compared with Monte Carlo-based model calculations. The largest shower, FRO 90174, includes eight fragments with an average terrestrial age of (100 ~ 30) ´ 103 years; the neutron-capture saturation activities extend to 27 dpm/kg stone for <span class="hlt">36</span><span class="hlt">Cl</span> and 19 dpm/kg stone for 41Ca. The concentrations of spallation produced <span class="hlt">10</span><span class="hlt">Be</span>, <span class="hlt">26</span><span class="hlt">Al</span> and <span class="hlt">36</span><span class="hlt">Cl</span> constrain the radius (R) to 80-100 cm, while the neutron-capture 41Ca activities indicate that the samples originated from the outer 25 cm. With a pre-atmospheric radius of 80-100 cm, FRO 90174 is among the largest of the Antarctic stony meteorites. The large pre-atmospheric size supports our hypothesis that at least 50 of the ~150 classified H5/H6-chondrites from the Frontier Mountain stranding area belong to this single fall; this hypothesis does not entirely account for the high H/L ratio at Frontier Mountain. The smaller shower, FRO 90001, includes four fragments with an average terrestrial age of (40 ~ 10) ´ 103 years; they contain small contributions of neutron-capture <span class="hlt">36</span><span class="hlt">Cl</span>, but no excess of 41Ca. FRO 90001 experienced a complex exposure history with high shielding conditions in the first stage (150 < R < 300 cm) and much lower shielding in the second stage (R < 30 cm), the latter starting ~1.0 million years (Ma) ago. Based on the measured <span class="hlt">10</span><span class="hlt">Be</span>/21Ne and <span class="hlt">26</span><span class="hlt">Al</span>/21Ne ratios, the cosmic-ray exposure ages of the two showers are 7.2 ~ 0.5 Ma for FRO 90174 and 8 ~ 1 Ma for FRO 90001. These ages coincide with the well-established H</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.189...70K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.189...70K"><span id="translatedtitle">A link between oxygen, calcium and titanium isotopes in <span class="hlt">26</span><span class="hlt">Al</span>-poor hibonite-rich CAIs from Murchison and implications for the heterogeneity of dust reservoirs in the solar nebula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kööp, Levke; Davis, Andrew M.; Nakashima, Daisuke; Park, Changkun; Krot, Alexander N.; Nagashima, Kazuhide; Tenner, Travis J.; Heck, Philipp R.; Kita, Noriko T.</p> <p>2016-09-01</p> <p>PLACs (platy hibonite crystals) and related hibonite-rich calcium-, aluminum-rich inclusions (CAIs; hereafter collectively referred to as PLAC-like CAIs) have the largest nucleosynthetic isotope anomalies of all materials believed to have formed in the solar system. Most PLAC-like CAIs have low inferred initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios and could have formed prior to injection or widespread distribution of <span class="hlt">26</span><span class="hlt">Al</span> in the solar nebula. In this study, we report <span class="hlt">26</span><span class="hlt">Al</span>-26Mg systematics combined with oxygen, calcium, and titanium isotopic compositions for a large number of newly separated PLAC-like CAIs from the Murchison CM2 chondrite (32 CAIs studied for oxygen, 26 of these also for <span class="hlt">26</span><span class="hlt">Al</span>-26Mg, calcium and titanium). Our results confirm (1) the large range of nucleosynthetic anomalies in 50Ti and 48Ca (our data range from -70‰ to +170‰ and -60‰ to +80‰, respectively), (2) the substantial range of Δ17O values (-28‰ to -17‰, with Δ17O = δ17O - 0.52 × δ18O), and (3) general <span class="hlt">26</span><span class="hlt">Al</span>-depletion in PLAC-like CAIs. The multielement approach reveals a relationship between Δ17O and the degree of variability in 50Ti and 48Ca: PLAC-like CAIs with the highest Δ17O (∼-17‰) show large positive and negative 50Ti and 48Ca anomalies, while those with the lowest Δ17O (∼-28‰) have small to no anomalies in 50Ti and 48Ca. These observations could suggest a physical link between anomalous 48Ca and 50Ti carriers and an 16O-poor reservoir. We suggest that the solar nebula was isotopically heterogeneous shortly after collapse of the protosolar molecular cloud, and that the primordial dust reservoir, in which anomalous carrier phases were heterogeneously distributed, was 16O-poor (Δ17O ⩾ -17‰) relative to the primordial gaseous (CO + H2O) reservoir (Δ17O < -35‰). However, other models such as CO self-shielding in the protoplanetary disk are also considered to explain the link between oxygen and calcium and titanium isotopes in PLAC-like CAIs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMEP23C0776F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMEP23C0776F"><span id="translatedtitle">Constraining Regolith Production on a Hillslope Over Long Timescales: Interpreting In Situ <span class="hlt">10</span><span class="hlt">Be</span> Concentrations on an Evolving Landscape</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Foster, M. A.; Anderson, R. S.; Duehnforth, M.; Kelly, P. J.</p> <p>2011-12-01</p> <p>In situ produced <span class="hlt">10</span><span class="hlt">Be</span> cosmogenic radionuclide (CRN) concentrations provide geomorphologists with a quantitative tool to calculate regolith production rates in a variety of landscapes. However, the power of CRN dating is limited by the care with which these hard-earned numbers are interpreted. As rock is exhumed through the weathered zone, it accumulates in situ produced CRNs. Most studies assume a steady-state condition to calculate regolith production rates from <span class="hlt">10</span><span class="hlt">Be</span> concentrations obtained from rock at the base of mobile regolith; ignoring decay, the regolith production rate becomes simply Poe-H/z*/[<span class="hlt">10</span><span class="hlt">Be</span>]. Although the balance of regolith production and the spatial pattern of divergence required to maintain steady regolith thickness is valid in some landscapes, steady-state is unlikely on hillslopes where time scales for generating soils are longer than climatic cycles. We report in situ <span class="hlt">10</span><span class="hlt">Be</span> concentrations to calculate production rates for mobile regolith in 8 soil pits along north- and south-facing slopes in Gordon Gulch, an intensively studied catchment in the Boulder Creek CZO. Gordon Gulch hillslopes exhibit variable regolith and saprolite thicknesses over gneissic and granitic parent rock; mean regolith thickness is 0.65 m. Local denudation rates in nearby catchments are 25 ± 8 m/Ma (Dethier and Lazarus, 2006). The mean residence time of mobile regolith in Gordon Gulch catchment is therefore 20-45 ka; less than half of this time is spent in Holocene climatic conditions. Although Gordon Gulch presently has mean annual temperature (MAT) ~4°C, it was likely at least 6°C cooler during the Last Glacial Maximum, meaning that periglacial conditions likely dominated. We therefore anticipate that parent rock could be more rapidly damaged by increased frost-cracking, and regolith transport be enhanced by increased frost-heave; thus steady-state conditions cannot be assumed over this timescale. To develop strategies for interpretation of <span class="hlt">10</span><span class="hlt">Be</span>, we employ a 1D</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70171236','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70171236"><span id="translatedtitle">Denudation rates determined from the accumulation of in situ-produced <span class="hlt">10</span><span class="hlt">Be</span> in the luquillo experimental forest, Puerto Rico</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Brown, Erik Thorson; Stallard, Robert F.; Larsen, Matthew C.; Raisbeck, Grant M.; Yiou, Francoise</p> <p>1995-01-01</p> <p>We present a simple method for estimation of long-term mean denudation rates using in situ-produced cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> in fluvial sediments. Procedures are discussed to account for the effects of soil bioturbation, mass wasting and attenuation of cosmic rays by biomass and by local topography. Our analyses of <span class="hlt">10</span><span class="hlt">Be</span> in quartz from bedrock outcrops, soils, mass-wasting sites and riverine sediment from the Icacos River basin in the Luquillo Experimental Forest, Puerto Rico, are used to characterize denudation for major landform elements in that basin. The <span class="hlt">10</span><span class="hlt">Be</span> concentration of a discharge-weighted average of size classes of river sediment corresponds to a long-term average denudation of ≈ 43 m Ma −1, consistent with mass balance results. </p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EPJA...52..179K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EPJA...52..179K"><span id="translatedtitle">13C(n,α0)<span class="hlt">10</span><span class="hlt">Be</span> cross section measurement with sCVD diamond detector</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kavrigin, P.; Griesmayer, E.; Belloni, F.; Plompen, A. J. M.; Schillebeeckx, P.; Weiss, C.</p> <p>2016-06-01</p> <p>This paper presents 13C(n, α0)<span class="hlt">10</span><span class="hlt">Be</span> cross section measurements performed at the Van de Graaff facility of the Joint Research Centre Geel. The 13C(n, α0)<span class="hlt">10</span><span class="hlt">Be</span> cross section was measured relative to the 12C(n, α0)9Be cross section at 14.3 MeV and 17.0 MeV neutron energies. The measurements were performed with an sCVD (single-crystal chemical vapor deposition) diamond detector which acted as sample and as sensor simultaneously. A novel analysis technique was applied, which is based on the pulse-shape analysis of the detector's ionization current. This technique resulted in an efficient separation of background events and consequently in a well-determined selection of the nuclear reaction channels 12C(n, α0)9Be and 13C(n, α0)<span class="hlt">10</span><span class="hlt">Be</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.6357B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.6357B"><span id="translatedtitle">A new <span class="hlt">10</span><span class="hlt">Be</span> record recovered from an Antarctic ice core: validity and limitations to record the solar activity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baroni, Mélanie; Bard, Edouard; Aster Team</p> <p>2015-04-01</p> <p>Cosmogenic nuclides provide the only possibility to document solar activity over millennia. Carbon-14 (14C) and beryllium-10 (<span class="hlt">10</span><span class="hlt">Be</span>) records are retrieved from tree rings and ice cores, respectively. Recently, 14C records have also proven to be reliable to detect two large Solar Proton Events (SPE) (Miyake et al., Nature, 2012, Miyake et al., Nat. Commun., 2013) that occurred in 774-775 A.D. and in 993-994 A.D.. The origin of these events is still under debate but it opens new perspectives for the interpretation of <span class="hlt">10</span><span class="hlt">Be</span> ice core records. We present a new <span class="hlt">10</span><span class="hlt">Be</span> record from an ice core from Dome C (Antarctica) covering the last millennium. The chronology of this new ice core has been established by matching volcanic events on the WAIS Divide ice core (WDC06A) that is the best dated record in Antarctica over the Holocene (Sigl et al., JGR, 2013, Sigl et al., Nat. Clim. Change, 2014). The five minima of solar activity (Oort, Wolf, Spörer, Maunder and Dalton) are detected and characterized by a <span class="hlt">10</span><span class="hlt">Be</span> concentration increase of ca. 20% above average in agreement with previous studies of ice cores drilled at South Pole and Dome Fuji in Antarctica (Bard et al., EPSL, 1997; Horiuchi et al., Quat. Geochrono., 2008) and at NGRIP and Dye3 in Greenland (Berggren et al., GRL, 2009). The high resolution, on the order of a year, allows the detection of the 11-year solar cycle. Sulfate concentration, a proxy for volcanic eruptions, has also been measured in the very same samples, allowing a precise comparison of both <span class="hlt">10</span><span class="hlt">Be</span> and sulfate profiles. We confirm the systematic relationship between stratospheric eruptions and <span class="hlt">10</span><span class="hlt">Be</span> concentration increases, first evidenced by observations of the stratospheric volcanic eruptions of Agung in 1963 and Pinatubo in 1991 (Baroni et al., GCA, 2011). This relationship is due to an increase in <span class="hlt">10</span><span class="hlt">Be</span> deposition linked to the role played by the sedimentation of volcanic aerosols. In the light of these new elements, we will discuss the limitations and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....3931C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....3931C"><span id="translatedtitle">High-resolution authigenic <span class="hlt">10</span><span class="hlt">Be</span>/9Be records : A proxy indicator of the past geomagnetic field variability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carcaillet, J.; Thouveny, N.; Bourlès, D. L.</p> <p>2003-04-01</p> <p>At global scale, the synchronicity of abnormal directions of the paleomagnetic field and minimum intensities supports the hypothesis of a relationship between the occurrence of excursions and/or polarity changes and the collapse of the dipolar component. We present quantitative evaluations of relationships between <span class="hlt">10</span><span class="hlt">Be</span> production rate variations and geomagnetic events using high resolution authigenic <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios and continuous paleointensity records measured in three marine sediment sequences located on the Portuguese margin, (MD95-2042 and MD95-2040), and in the Western Pacific, (MD97-2140). Since <span class="hlt">10</span><span class="hlt">Be</span> concentrations measured in marine sediments not only depend on <span class="hlt">10</span><span class="hlt">Be</span> production rates but also on oceanic and sedimentary effects, authigenic (i.e. adsorbed onto particles from the water column) <span class="hlt">10</span><span class="hlt">Be</span> concentrations were normalized to their related authigenic 9Be concentrations in order to account for these disturbing effects on the sedimentation rate as well as on the chemical and granulometric composition of the sediments. Due to their different sources, only the soluble form of both beryllium isotopes may indeed have been homogenized in the water column before deposition in the sediment. The measured <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios increase significantly at all identified excursions and reversals, associated with decreased paleointensities, consistently with the expected relationship between magnetic moment and cosmic ray flux (Q/Qo=(M/Mo)-1/2). Our results confirm the global occurrence of well-recognized and well-dated phases of low geomagnetic moments associated to well known geomagnetic excursions, short events or polarity reversals that occurred between 0 and 300 ka BP and between 0.6 and 1.3 Ma BP: the Laschamp excursion, the Blake event, the Jamaica/Pringle falls excursion, the Brunhes-Matuyama Reversal, the upper and lower Jaramillo transitions and the Cobb Mountain event. They strengthen the validity of recently reported excursions: Icelandic basin, Calabrian Ridge 0</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JGRF..117.1023D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JGRF..117.1023D"><span id="translatedtitle">Unsteady late Pleistocene incision of streams bounding the Colorado Front Range from measurements of meteoric and in situ <span class="hlt">10</span><span class="hlt">Be</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dühnforth, Miriam; Anderson, Robert S.; Ward, Dylan J.; Blum, Alex</p> <p>2012-03-01</p> <p>Dating of gravel-capped strath terraces in basins adjacent to western U.S. Laramide Ranges is one approach to document the history of late Cenozoic fluvial exhumation. We use in situ <span class="hlt">10</span><span class="hlt">Be</span> measurements to date the broad surfaces adjacent to the eastern edge of the Rocky Mountains in Colorado, and compare these calculated ages with results from meteoric <span class="hlt">10</span><span class="hlt">Be</span> measurements. We analyze three sites near Boulder, Colorado (Gunbarrel Hill, Table Mountain, and Pioneer) that have been mapped as the oldest terrace surfaces with suggested ages ranging from 640 ka to the Plio-Pleistocene transition. Our in situ <span class="hlt">10</span><span class="hlt">Be</span> results reveal abandonment ages of 95 ± 129 ka at Table Mountain, 175 ± 27 ka at Pioneer, and ages of 251 ± 10 ka and 307 ± 15 ka at Gunbarrel Hill. All are far younger than previously thought. Inventories of meteoric <span class="hlt">10</span><span class="hlt">Be</span> support this interpretation, yielding ages that are comparable to Table Mountain and ˜20% lower than Pioneer in situ ages. We argue that lateral beveling by rivers dominated during protracted times of even moderate glacial climate, and that vertical incision rates of several mm/yr likely occurred during times of very low sediment supply during the few interglacials that were characterized by particularly warm climate conditions. In contrast to the traditional age chronology in the area, our ages suggest that the deep exhumation of the western edge the High Plains occurred relatively recently and at an unsteady pace.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.C41A0440W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.C41A0440W"><span id="translatedtitle">Cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> Depth Profile in top 560 m of West Antarctic Ice Sheet Divide Ice Core</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Welten, K. C.; Woodruff, T. E.; Caffee, M. W.; Edwards, R.; McConnell, J. R.; Bisiaux, M. M.; Nishiizumi, K.</p> <p>2009-12-01</p> <p>Concentrations of cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> in polar ice samples are a function of variations in solar activity, geomagnetic field strength, atmospheric mixing and annual snow accumulation rates. The <span class="hlt">10</span><span class="hlt">Be</span> depth profile in ice cores also provides independent chronological markers to tie Antarctic to Greenland ice cores and to tie Holocene ice cores to the 14C dendrochronology record. We measured <span class="hlt">10</span><span class="hlt">Be</span> concentrations in 187 samples from depths of 0-560 m of the main WAIS Divide core, WDC06A. The ice samples are typically 1-2 kg and represent 2-4 m of ice, equivalent to an average temporal resolution of ~12 years, based on the preliminary age-depth scale proposed for the WDC core, (McConnell et al., in prep). Be, Al and Cl were separated using ion exchange chromatography techniques and the <span class="hlt">10</span><span class="hlt">Be</span> concentrations were measured by accelerator mass spectrometry (AMS) at PRIME lab. The <span class="hlt">10</span><span class="hlt">Be</span> concentrations range from 8.1 to 19.1 x 10^3 at/g, yielding an average of (13.1±2.1) x 10^3 at/g. Adopting an average snow accumulation rate of 20.9 cm weq/yr, as derived from the age-depth scale, this value corresponds to an average <span class="hlt">10</span><span class="hlt">Be</span> flux of (2.7±0.5) x 10^5 atoms/yr/cm2. This flux is similar to that of the Holocene part of the Siple Dome (Nishiizumi and Finkel, 2007) and Dome Fuji (Horiuchi et al. 2008) ice cores, but ~30% lower than the value of 4.0 x 10^5 atoms/yr/cm2 for GISP2 (Finkel and Nishiizumi, 1997). The periods of low solar activity, known as Oort, Wolf, Spörer, Maunder and Dalton minima, show ~20% higher <span class="hlt">10</span><span class="hlt">Be</span> concentrations/fluxes than the periods of average solar activity in the last millennium. The maximum <span class="hlt">10</span><span class="hlt">Be</span> fluxes during some of these periods of low solar activity are up to ~50% higher than average <span class="hlt">10</span><span class="hlt">Be</span> fluxes, as seen in other polar ice cores, which makes these peaks suitable as chronologic markers. We will compare the <span class="hlt">10</span><span class="hlt">Be</span> record in the WAIS Divide ice core with that in other Antarctic as well as Greenland ice cores and with the 14C treering record. Acknowledgment. This</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMPP11B1822B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMPP11B1822B"><span id="translatedtitle">Orbital forcing of the East Asian summer monsoon based on quantitative paleorainfall records from Chinese Loess using <span class="hlt">10</span><span class="hlt">Be</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beck, W.; White, L.; Cheng, L.; Wu, Z.; zhou, W.; Kong, X.</p> <p>2013-12-01</p> <p>Here we outline a method for deriving quantitative records of paleoprecipitation using meteoric <span class="hlt">10</span><span class="hlt">Be</span> flux as recorded in Quaternary loess sediments, and apply this method to derive a ~500ka rainfall record from Chinese loess. The method involves measuring loess <span class="hlt">10</span><span class="hlt">Be</span> concentration by AMS, then applying corrections for radioactive decay, recycled <span class="hlt">10</span><span class="hlt">Be</span> in reaerosolized dust, and for variations in geomagnetic field to correct for atmospheric <span class="hlt">10</span><span class="hlt">Be</span> production rate variations. <span class="hlt">10</span><span class="hlt">Be</span> flux is calculated by multiplying the corrected <span class="hlt">10</span><span class="hlt">Be</span> concentrations with loess accumulation rate, where the later is derived from a (non-orbitally tuned) timescale determined from correlating variations in loess magnetic susceptibility with U/Th dated Chinese speleothem δ18O records. The dependence of <span class="hlt">10</span><span class="hlt">Be</span> flux on rainfall rate is determined using modern observations of 7Be flux in rainfall, and atmospheric <span class="hlt">10</span><span class="hlt">Be</span>/7Be cosmogenic nuclide production ratios. Modern rainfall on the Chinese Loess Plateau has been shown to be primarily a function of East Asian Summer Monsoon (EASM) intensity. Our <span class="hlt">10</span><span class="hlt">Be</span> rainfall proxy shows that glacial to peak interglacial rainfall rates in this region have varied by about a factor of two over the last 0.5 Ma. Our results suggests EASM intensity during interglacials MIS11, MIS 9c and MIS13 were all comparable (~850 mm/yr), but slightly less (by ~8%) than for MIS1, and about 15% less than for MIS5e, which is similar to the high latitude ice volume pattern of response except for MIS11. We note that the <span class="hlt">10</span><span class="hlt">Be</span> rainfall record of MIS13 differs from typical Chinese loess magnetic susceptibility records that suggest MIS13 was the strongest EASM of the last 6 interglacials. Our record instead indicates a relative subdued MIS13 EASM, more consistent with the Antarctic EPICA ice core deuterium or marine δ18O records. We correlate our results with orbital forced solar insolation variations at high and low latitudes as well as with interhemispheric insolation gradients. We find</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.8159B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.8159B"><span id="translatedtitle">Using <span class="hlt">10</span>-<span class="hlt">Be</span> in sediment to understand the long-term behavior of the Greenland Ice Sheet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bierman, Paul; Rood, Dylan; Corbett, Lee; Nelson, Alice; Shakun, Jeremy</p> <p>2013-04-01</p> <p>We have used in situ and meteoric cosmogenic <span class="hlt">10</span>-<span class="hlt">Be</span>, measured in sediment and rock, to understand better the history and erosional processes of the Greenland Ice Sheet over the many thousand to several million-year time scale. Measured concentrations of in situ <span class="hlt">10</span>-<span class="hlt">Be</span> constrain Holocene emergence histories at the head of Igaliku fiord in southern Greenland. We sampled two well-preserved gravel beach ridges that are the highest marine deposits. Below one beach ridge, we sampled 4 quartzite outcrops at progressively lower elevations and above a nearby beach ridge, we sampled an erratic boulder and the underlying bedrock. We also sampled a beach ridge at a similar elevation at Qassiarsuk on Tunulliarfik Fiord about 20 km away. The data show rapid emergence after 11 ky. All three beach ridges (average and standard error of 6, 6 and 10 clast ages) have the same age (10.98±0.09, 11.07±0.51ky, and 10.96±0.33 ky). Ages of outcrops below the beach ridges are in stratigraphic order and show steady emergence; the outcrop just above modern high water has an age of 8.80 ky. The bedrock/boulder ages from above the beach ridge are slightly younger (10.45 and 10.73 ky, respectively), consistent with inheritance of about 1400 atoms/g <span class="hlt">10</span>-<span class="hlt">Be</span> in beach clasts. Low levels of inheritance in deglacial beach gravels are consistent with the <span class="hlt">10</span>-<span class="hlt">Be</span> content of clasts collected directly from the GIS in western Greenland. Most clasts have the equivalent of only a few hundred to a few thousand atoms/g <span class="hlt">10</span>-<span class="hlt">Be</span>. Sand-sized sediment collected from outwash streams exiting the ice margin at Kangerlussuaq (western Greenland), Narsarsuaq (southern Greenland), and Tasilaq (eastern Greenland) has two to five thousand atoms/g of <span class="hlt">10</span>-<span class="hlt">Be</span> - several times the median amount of in situ <span class="hlt">10</span>-<span class="hlt">Be</span> measured in clasts collected from the ice. These data indicate efficient erosion by the ice sheet of both pre-glacial and interglacial regolith at least near the ice sheet margins. In contrast, chemical and meteoric <span class="hlt">10</span>-<span class="hlt">Be</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMPP24B..08Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMPP24B..08Z"><span id="translatedtitle">The study of the geomagnetic excursions and the relative intensities from Chinese loess <span class="hlt">10</span><span class="hlt">Be</span> over the past 130 ka</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, W.; Xian, F.; Beck, J.; An, Z.; Wu, Z.; Liu, M.; Chen, M.; Priller, A.; Kutschera, W.; Jull, A. T.; Yu, H.; Song, S.; Cheng, P.; Kong, X.</p> <p>2009-12-01</p> <p>Chinese loess is well-known archive for the paleogeomagnetic and paleoclimatic studies [Zhou et al., 1990; An et al., 1990; Zhu et al., 2007]. However, earlier efforts to extract weak geomagnetic excursion signals from Chinese loess <span class="hlt">10</span><span class="hlt">Be</span> were always unsuccessful due to the complexities of loess <span class="hlt">10</span><span class="hlt">Be</span>, which results in the fact that loess <span class="hlt">10</span><span class="hlt">Be</span> was only used as a climatic proxy [Shen et al., 1992; Beer et al.,1993; Gu et al.,1996]. Meanwhile, knowledge on the precise stratigraphic horizons of geomagnetic excursions with a reliable dating [Channell, 2006], on whether the short-lived excursions such as Blake can not be recorded in paleosol unit are still controversial. Here, we present the reconstructed past 130ka geomagnetic excursions and relative paleointensities for the first time from <span class="hlt">10</span><span class="hlt">Be</span> records in two Chinese loess sections. Results are comparative with those of independent geomagnetic research on Atlantic and Pacific sediments. The derived Laschamp and Blake events lie in the loess-paleosol (L1SS1 and S1SS3) corresponding to mid MIS 3 and 5e respectively. Our studies prove the potential application of the complex loess <span class="hlt">10</span><span class="hlt">Be</span> for long-term geomagnetic tracing and provide new evidence to answer the long-existing debates on the precise stratigraphic horizon of geomagnetic excursions. Our study suggests the potential application of loess-paleosol <span class="hlt">10</span><span class="hlt">Be</span> for reconstructing geomagnetic intensity variations spanning the whole Quaternary. References 1. Zhou, L. P., F. Oldfield, A. G. Wintle, S. G. Robinson, and J. T. Wang (1990), Partly pedogenic origin of magnetic variations in Chinese loess, Nature, 346, 737-739. 2. An, Z. S., T. S. Liu, Y. C. Lu, S. C. Porter, G. Kukla, X. H. Wu, and Y. M. Hua (1990), The long-term paleomonsoon variation recorded by the loess-paleosol sequence in Central China, Quat. Int., 7-8, 91-95. 3. Zhu, R. X., R. Zhang, C. L. Deng, Y. X. Pan, Q. S. Liu, and Y. B. Sun (2007), Are Chinese loess deposits essentially continuous?, Geophys. Res. Lett</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.1140D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.1140D"><span id="translatedtitle">Synchronizing the North American Varve Chronology with Greenland ice core records during late MIS 2 using Meteoric <span class="hlt">10</span><span class="hlt">Be</span> Flux</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>DeJong, Benjamin D.; Balco, Greg; Ridge, Jack C.; Rood, Dylan H.; Bierman, Paul R.</p> <p>2013-04-01</p> <p>The North American Varve Chronology (NAVC) is a floating 5700-year sequence of glacial lake varves deposited in the Connecticut River Valley of the northeast US ~18,000-12,500 years ago. The NAVC is an annually resolved record of regional climate and ice-marginal processes at 40-45° N latitude, near the margin of the retreating Laurentide Ice Sheet (LIS). NAVC deposition occurred at the same time as rapid and abrupt Arctic and North Atlantic climate changes that took place during the last deglaciation. Age calibration estimates for the NAVC based on radiocarbon dated plant macrofossils in individual varves imply a relationship between ice-marginal events recorded by the NAVC and climate events recorded in Greenland ice cores. For example, the retreat rate of the LIS up the Connecticut River Valley increased during the Bolling warming in Greenland, a readvance of the LIS margin took place during the Older Dryas cold period, and a correlation between an outburst flood from glacial Lake Iroquois and the Intra-Allerod Cold Period supports the hypothesis that the flood affected North Atlantic thermohaline circulation. On the other hand, a doubling of the ice-margin retreat rate recorded by the NAVC around 16,000 years ago coincides with a relatively cold period in Greenland. Our goal is to investigate the precise time relationship between these two records by synchronizing the NAVC with the Greenland ice core time scale using atmospherically-produced <span class="hlt">10</span><span class="hlt">Be</span>. Existing <span class="hlt">10</span><span class="hlt">Be</span> flux records, including those from Greenland ice cores, exhibit solar variability on a range of time scales. Because this variability is globally synchronous, a <span class="hlt">10</span><span class="hlt">Be</span> flux record for the NAVC can, in principle, be used to align NAVC and ice core timescales. In the first phase of this research we tested this potential by generating <span class="hlt">10</span><span class="hlt">Be</span> flux records for two 80-year varve sequences and analyzing them using multi-taper spectral analysis for determination of statistically significant periodicities. We were</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Geomo.241..122C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Geomo.241..122C"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span>-derived denudation rates from the Burdekin catchment: The largest contributor of sediment to the Great Barrier Reef</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Croke, Jacky; Bartley, Rebecca; Chappell, John; Austin, Jenet M.; Fifield, Keith; Tims, Stephen G.; Thompson, Chris J.; Furuichi, Takahisa</p> <p>2015-07-01</p> <p>Terrestrial cosmogenic nuclides (TCNs) such as Beryllium-10 (<span class="hlt">10</span><span class="hlt">Be</span>) are now routinely used to reconstruct erosional rates over tens of thousands of years at increasingly large basin scales (> 100,000 km2). In Australia, however, the approach and its assumptions have not been systematically tested within a single, large drainage basin. This study measures <span class="hlt">10</span><span class="hlt">Be</span> concentrations in river sediments from the Burdekin catchment, one of Australia's largest coastal catchments, to determine long-term (> 10,000 years), time-integrated rates of sediment generation and denudation. A nested-sampling design was used to test for effects of increasing catchment scale on nuclide concentrations with upstream catchment areas ranging from 4 to 130,000 km2. Beryllium-10 concentrations in sediment samples collected from the upstream headwater tributaries and mid-stream locations range from 1.8 to 2.89 × 105 atoms g- 1 and data confirm that nuclide concentrations are well and rapidly mixed downstream. Sediment from the same tributaries consistently yielded <span class="hlt">10</span><span class="hlt">Be</span> concentrations in the range of their upstream samples. Overall, no decrease in <span class="hlt">10</span><span class="hlt">Be</span> concentrations can be observed at the range of catchment scales measured here. The mean denudation rate for all river sediment samples throughout the Fanning subcatchment (1100 km2) is 18.47 m Ma- 1, which compares with the estimate at the end of the Burdekin catchment (130,000 km2) of 16.22 m Ma- 1. Nuclide concentrations in the lower gradient western and southern catchments show a higher degree of variability, and several complications emerged as a result of the contrasting geomorphic processes and settings. This study confirms the ability of TCNs to determine long-term denudation rates in Australia and highlights some important considerations in the model assumptions that may affect the accuracy of limited sampling in large, low-gradient catchments with long storage times.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C14A..08Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C14A..08Y"><span id="translatedtitle">Quantifying Sub-Glacial Abrasion at Jakobshavn Isbræ: A Novel Approach Using In Situ <span class="hlt">10</span><span class="hlt">Be</span> Measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Young, N. E.; Briner, J. P.; Schaefer, J. M.</p> <p>2015-12-01</p> <p>Warm-based ice sheets and glaciers incontrovertibly erode and modify the terrain that they mantle; yet precise estimates of the rate and magnitude of sub-glacial erosion are rare. Estimates of sub-glacial erosion occurring beneath ice sheets, such as the Greenland Ice Sheet, are particularly important because they can provide key insights into sediment availability at ice-sheet margins that influences ice-sheet stability. Furthermore, estimates of sub-glacial erosion can help inform predictive geophysical ice-sheet models that incorporate a basal sliding parameter. Here, we take advantage of a detailed ice-margin history at Jakobshavn Isbræ over the last ~7,500 years, combined with in situ <span class="hlt">10</span><span class="hlt">Be</span> measurements from strategic bedrock locations, to quantify the rate of sub-glacial abrasion beneath Jakobshavn Isbræ's land-based margins. Our bedrock samples are from 1) locations that deglaciated ~7,500 years ago and have remained ice-free through present day, and 2) locations that also deglaciated ~7,500 years ago, but were re-occupied by the ice-margin during the last few hundred years. After accounting for the slightly different exposure histories between bedrock locations, and despite the short duration in ice-cover, initial <span class="hlt">10</span><span class="hlt">Be</span> measurements reveal a detectable difference in <span class="hlt">10</span><span class="hlt">Be</span> concentrations between the two bedrock surfaces. We hypothesize that the offset in <span class="hlt">10</span><span class="hlt">Be</span> concentrations reveals the magnitude of sub-glacial abrasion beneath Jakobshavn Isbræ's land-terminating margins.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1714367H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1714367H"><span id="translatedtitle">Observations of historical sea cliff retreat rates exceed long-term estimates derived from cosmogenic <span class="hlt">10</span><span class="hlt">Be</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hurst, Martin D.; Rood, Dylan H.; Ellis, Michael A.; Anderson, Robert S.</p> <p>2015-04-01</p> <p>Historical observation of coastal retreat are limited to relatively short timescales (< 150 years), during which time humans may have modified the coastal environment. There is growing concern that rates of coastal change may be accelerated in the face of anticipated stormier climates and rising sea level, yet there is little knowledge of rates of coastal change prior to the relatively brief historical records. In order to make predictions about potential future coastal change it is important to establish baseline conditions averaged over longer time periods. Here we present analysis of sea cliff retreat throughout the Holocene averaged for chalk cliffs in south-east England using cosmogenic isotopes. We determine long-term rates of sea cliff erosion from <span class="hlt">10</span><span class="hlt">Be</span> measured from in-situ flint samples collected from three transects across coastal platforms in East Sussex. A numerical model of <span class="hlt">10</span><span class="hlt">Be</span> accumulation on an evolving coastal profile allows estimation of cliff retreat rate during the Holocene. The model accounts for variation in <span class="hlt">10</span><span class="hlt">Be</span> accumulation with tides and sea-level rise, and takes into account platform downwear and topographic shielding by adjacent cliffs. We find that cliff retreat rates during the Holocene were significantly slower (2-6 cm yr-1) than those derived from recent historical observations (15-25 cm yr-1). Modelled accumulation of <span class="hlt">10</span><span class="hlt">Be</span> requires retreat rates that increase rapidly in recent times, potentially reflecting human modification of the coastal sediment budget through construction of sea defences, flood defenses and aggregate extraction. Therefore knowledge of past human activity at the coastline may be important in anticipating future rates of coastal retreat.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008GeoRL..35.5817H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008GeoRL..35.5817H"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> measured in a GRIP snow pit and modeled using the ECHAM5-HAM general circulation model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heikkilä, U.; Beer, J.; Jouzel, J.; Feichter, J.; Kubik, P.</p> <p>2008-03-01</p> <p><span class="hlt">10</span><span class="hlt">Be</span> measured in a Greenland Ice Core Project (GRIP) snow pit (1986-1990) with a seasonal resolution is compared with the ECHAM5-HAM GCM run. The mean modeled <span class="hlt">10</span><span class="hlt">Be</span> concentration in ice (1.0.104 atoms/g) agrees well with the measured value (1.2.104 atoms/g). The measured <span class="hlt">10</span><span class="hlt">Be</span> deposition flux (88 atoms/m2/s) also agrees well with the modeled flux (69 atoms/m2/s) and the measured precipitation rate (0.67 mm/day) agrees with the modeled rate (0.61 mm/day). The mean surface temperature of -31°C estimated from δ 18O is lower than the temperature measured at a near-by weather station (-29°C) and the modeled temperature (-26°C). During the 5-year period the concentrations and deposition fluxes, both measured and modeled, show a decreasing trend consistent with the increase in the solar activity. The variability of the measured and modeled concentrations and deposition fluxes is very similar suggesting that the variability is linked to a variability in production rather than the local meteorology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21191997','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21191997"><span id="translatedtitle">Coexistence of {alpha}+{alpha}+n+n and {alpha}+t+t cluster structures in {sup <span class="hlt">10</span>}<span class="hlt">Be</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Itagaki, N.; Ito, M.; Milin, M.; Hashimoto, T.; Ishiyama, H.; Miyatake, H.</p> <p>2008-06-15</p> <p>The coexistence of the {alpha}+{alpha}+n+n and {alpha}+t+t cluster structures in the excited states of {sup <span class="hlt">10</span>}<span class="hlt">Be</span> has been discussed. In the previous analysis, all the low-lying states of {sup <span class="hlt">10</span>}<span class="hlt">Be</span> were found to be well described by the motion of the two valence neutrons around two {alpha} clusters. However, the {alpha}+t+t cluster structure was found to coexist with the {alpha}+{alpha}+n+n structure around E{sub x}=15 MeV, close to the corresponding threshold. We have introduced a microscopic model to solve the coupling effect between these two configurations. The K=0 and K=1 states are generated from the {alpha}+t+t configurations due to the spin coupling of two triton clusters. The present case of {sup <span class="hlt">10</span>}<span class="hlt">Be</span> is one of the few examples in which completely different configurations of triton-type ({alpha}+t+t three-center) and {alpha}-type ({alpha}+{alpha}+n+n two-center) clusters coexist in a single nucleus in the same energy region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMEP41D0835S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMEP41D0835S"><span id="translatedtitle">Spatial patterns of mobile regolith thickness and meteoric <span class="hlt">10</span><span class="hlt">Be</span> in the Boulder Creek Critical Zone Observatory, Front Range, Colorado</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shea, N.; Ouimet, W. B.; Dethier, D. P.; Bierman, P. R.; Rood, D. H.</p> <p>2012-12-01</p> <p>The Boulder Creek Critical Zone Observatory (BcCZO) aims to understand the history, architecture and evolution of hillslopes found within the diverse topography and climate regimes of the Colorado Front Range. This information is crucial for testing and developing models of hillslope evolution, giving especial consideration to the production and downslope transport of mobile regolith on the hillslopes. Here, we present the results of a systematic study aiming to document spatial patterns of mobile regolith thickness and meteoric Beryllium-10 (<span class="hlt">10</span><span class="hlt">Be</span>) concentrations in the Gordon Gulch basin of the BcCZO. Gordon Gulch lies within the unglaciated portion of the Colorado Front Range and is thought to be an artifact of long-term steady state evolution. The basin is characterized by mixed bedrock-soil mantled hillslopes, with intermittent bedrock outcrops (tors) on ~10% of slopes. It is currently unclear how the hillslopes of Gordon Gulch have evolved given the variable rock type and strength (i.e., fracture spacing), gradients (steep slopes in lower basin compared to gradual in the upper), and hillslope aspects (north versus south facing hillslopes, with varying tree types and soil moisture for frost cracking and heaving) that exist within the basin. Furthermore, climate data suggest that the current climate regime (relatively warm) is representative of only 20% of the last 65 ka. Mobile regolith thickness measurements provide a snapshot of hillslope evolution in the basin given these controls, and meteoric <span class="hlt">10</span><span class="hlt">Be</span> can used to constrain residence times and trace mobile regolith transport. We measure mobile regolith thickness as the depth to immobile weathered bedrock and/or saprolite. Preliminary analysis of over 200 soil pits reveals a high degree of variability in mobile regolith thickness. In general, the mobile regolith cover is thinner on the south facing slopes than the north facing and a general thickening of mobile regolith occurs on steeper slopes, especially along</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..DNP.KD004S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..DNP.KD004S"><span id="translatedtitle">Search for the isovector monopole resonance via the 28Si(<span class="hlt">10</span><span class="hlt">Be</span>,10B+ γ)28Al reaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scott, Michael; e11021 Collaboration Team</p> <p>2013-10-01</p> <p>The isovector giant monopole resonance (IVGMR) is a fundamental mode of collective oscillation in which the neutron and proton fluids in a nucleus radially expand and contract in an out-of-phase manner. Observation of the IVGMR has been difficult due to the lack of a probe that will excite only its non-spin-flip (ΔS = 0) transitions. The IVGMR's spin-transfer (ΔS = 1) counterpart, the isovector spin giant monopole resonance, is much more strongly excited at bombarding energies higher than 60 MeV/ u. By way of the (<span class="hlt">10</span><span class="hlt">Be</span>,10B+ γ) charge-exchange reaction, the selectivity for the excitation of the IVGMR can be gained. In this probe, the superallowed Fermi transition <span class="hlt">10</span><span class="hlt">Be</span>(0+,g.s.) -->10B(01+,1.74 MeV, T = 1) allows a nearly pure isolation of the ΔS = 0 component by detecting the 1022 keV gamma rays from the deexcitation of the 10B. We measured the double differential cross sections for the 28Si(<span class="hlt">10</span><span class="hlt">Be</span>,10B+ γ) reaction at 100 MeV/ u using the large acceptance S800 Spectrometer at the National Superconducting Cyclotron Laboratory with the GRETINA array detecting the gamma rays emitted from the 10B ejectile. In this presentation, we will report preliminary reults of the IVGMR in 28Al. GRETINA was funded by the US DOE - Office of Science. Operation of the array at NSCL is supported by NSF under Cooperative Agreement PHY-1102511(NSCL) and DOE under grant DE-AC02-05CH11231(LBNL).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015A%26A...577A..20I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015A%26A...577A..20I"><span id="translatedtitle">Grand solar minima and maxima deduced from <span class="hlt">10</span><span class="hlt">Be</span> and 14C: magnetic dynamo configuration and polarity reversal</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Inceoglu, F.; Simoniello, R.; Knudsen, M. F.; Karoff, C.; Olsen, J.; Turck-Chiéze, S.; Jacobsen, B. H.</p> <p>2015-05-01</p> <p>Aims: This study aims to improve our understanding of the occurrence and origin of grand solar maxima and minima. Methods: We first investigate the statistics of peaks and dips simultaneously occurring in the solar modulation potentials reconstructed using the Greenland Ice Core Project (GRIP) <span class="hlt">10</span><span class="hlt">Be</span> and IntCal13 14C records for the overlapping time period spanning between ~1650 AD to 6600 BC. Based on the distribution of these events, we propose a method to identify grand minima and maxima periods. By using waiting time distribution analysis, we investigate the nature of grand minima and maxima periods identified based on the criteria as well as the variance and significance of the Hale cycle during these kinds of events throughout the Holocene epoch. Results: Analysis of grand minima and maxima events occurring simultaneously in the solar modulation potentials, reconstructed based on the 14C and the <span class="hlt">10</span><span class="hlt">Be</span> records, shows that the majority of events characterized by periods of moderate activity levels tend to last less than 50 years: grand maxima periods do not last longer than 100 years, while grand minima can persist slightly longer. The power and the variance of the 22-year Hale cycle increases during grand maxima and decreases during grand minima, compared to periods characterized by moderate activity levels. Conclusions: We present the first reconstruction of the occurrence of grand solar maxima and minima during the Holocene based on simultaneous changes in records of past solar variability derived from tree-ring 14C and ice-core <span class="hlt">10</span><span class="hlt">Be</span>, respectively. This robust determination of the occurrence of grand solar minima and maxima periods will enable systematic investigations of the influence of grand solar minima and maxima episodes on Earth's climate.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984NIMPB...5..380B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984NIMPB...5..380B"><span id="translatedtitle">The camp century <span class="hlt">10</span><span class="hlt">Be</span> record: Implications for long-term variations of the geomagnetic dipole moment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beer, Jürg; Andree, Michael; Oeschger, Hans; Siegenthaler, Ulrich; Bonani, G.; Hofmann, H.; Morenzoni, E.; Nessi, M.; Suter, M.; Wölfli, W.; Finkel, R.; Langway, C.</p> <p>1984-11-01</p> <p><span class="hlt">10</span><span class="hlt">Be</span> concentrations measured in ice samples from Camp Century, Greenland, show short term variations which in general correspond to the 100-200 year "wiggles" in the 14C tree ring record. There is, however, no evidence for a long term variation over the last 5000 years. This constancy is in contrast to the approximately sinusoidal variation of the atmospheric 14C concentration which has generally been attributed to a changing geomagnetic dipole moment. This discrepancy implies that the 14C trend might stem from other causes such as changes of oceanic circulation processes or from higher production rates during the Wisconsin rather than from variation in the geomagnetic field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1817178C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1817178C"><span id="translatedtitle">Understanding complex exposure history of Mount Hampton, West Antarctica using cosmogenic 3He, 21Ne and <span class="hlt">10</span><span class="hlt">Be</span> in olivine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carracedo, Ana; Rodes, Angel; Stuart, Finlay; Smellie, John</p> <p>2016-04-01</p> <p>Combining stable and radioactive cosmogenic nuclides is an established tool for revealing the complexities of long-term landscape development. To date most studies have concentrated on 21Ne and <span class="hlt">10</span><span class="hlt">Be</span> in quartz. We have combined different chemical protocols for extraction of cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> from olivine, and measured concentrations in olivine from lherzolite xenoliths from the peak of Mount Hampton (~3,200 m), an 11 Ma shield volcano on the West Antarctic rift flank. We combine this data with cosmogenic 3He (and 21Ne) in the olivines in order to unravel the long-term environmental history of the region. The mean 3He/21Ne ratio (1.98 ± 0.22) is consistent with the theoretical value and previous determinations. <span class="hlt">10</span><span class="hlt">Be</span>/3He ratios (0.012 to 0.018) are significantly lower than the instantaneous production ratio (~0.045). The data are consistent with 1-3 Ma of burial. The altitude of the volcano rules out over-topping of the peak by the West Antarctic Ice Sheet only possible burial could be generated by the growth of an ice cap although this contradicts the absence of evidence for ice cover. The 3He-<span class="hlt">10</span><span class="hlt">Be</span> data can also be generated during episodic erosion of the volcanic ash over the last few million years. The data requires a minimum depth of 1 to 2.5 m for the samples during a minimum age of 5 Ma and maximum long-term erosion rate of ~0.5 m/Ma with at least one erosive episode reflecting short-term erosion rate of ~7 m/Ma that would have brought the samples into the surface during the last ~350 ka. Erosion in this type of landscape could be related to interglacial periods where cryostatic erosion can occur generating an increase in the erosion rate. This study shows that episodic erosion can produce stable-radioactive cosmogenic isotope systematics that are similar to those generated by exposure-burial cycles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016QuRes..85..107H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016QuRes..85..107H"><span id="translatedtitle">Rapid thinning of the Welsh Ice Cap at 20-19 ka based on <span class="hlt">10</span><span class="hlt">Be</span> ages</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hughes, Philip D.; Glasser, Neil F.; Fink, David</p> <p>2016-01-01</p> <p>New <span class="hlt">10</span><span class="hlt">Be</span> ages from the summits of three mountain areas of North Wales reveal a very similar exposure timing as the Welsh Ice Cap thinned after the global Last Glacial Maximum. Eight bedrock and one boulder sample gave a combined arithmetic mean exposure age of 19.08 ± 0.80 ka (4.2%, 1σ). Similar exposure ages over a 320 m vertical range (824 to 581 m altitude) show that ice cap thinning was very rapid and spatially uniform. Using the same production rate and scaling scheme, we recalculated six published <span class="hlt">10</span><span class="hlt">Be</span> exposure ages from the nearby Arans, which also covered a similar elevation range from 608 to 901 m and obtained an arithmetic mean of 19.41 ± 1.45 ka (7.5%, 1σ). The average exposure age of all 15 accepted deglaciation ages is 19.21 ± 1.07 (5.6%, 1σ). The complete dataset from North Wales provides very strong evidence indicating that these summits became exposed as nunataks at 20-19 ka. This result provides important insight to the magnitude of ice surface lowering and behavior of the Welsh Ice Cap during the last deglaciation that can be compared to other ice masses that made up the British-Irish Ice Sheet.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4350738','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4350738"><span id="translatedtitle">Synthèse et structure cristalline d’un matériau noir AgMnII 3(MnIII 0,<span class="hlt">26</span><span class="hlt">Al</span>0,74)(MoO4)5</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bouzidi, Chahira; Frigui, Wafa; Zid, Mohamed Faouzi</p> <p>2015-01-01</p> <p>A new silver aluminium trimangan­ese penta­molybdate {silver(I) trimanganese(II) aluminium penta­kis­[tetra­oxidomolybdate(VI)]}, AgMnII 3(MnIII 0,<span class="hlt">26</span><span class="hlt">Al</span>0,74)(MoO4)5, has been synthesized using solid-state methods. The structure is composed of M 2O10 dimers, M 3O14 (M = Mn, Al) trimers and MoO4 tetra­hedra sharing corners and forming three types of layers A, B and B′. The sequence of the constituting layers is A–BB′–A–BB′, with B′ obtained from B by inversion symmetry, forming a three-dimensional structure with large channels in which the positionally disordered and partially occupied Ag+ ions reside. The MnIII and AlIII atoms share the same site, M. AgMnII 3(MnIII 0,<span class="hlt">26</span><span class="hlt">Al</span>0,74)(MoO4)5 is isotypic with the NaMg3 X(MoO4)5 (X = Al, In) family and with NaFe4(MoO4)5. A comparative structural description is provided between the structure of the title compound and those of related phases containing dimers, trimers and tetra­mers. PMID:25844193</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFM.B22F..03C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFM.B22F..03C"><span id="translatedtitle">Application of in situ-produced <span class="hlt">10</span><span class="hlt">Be</span> to the study of Australian stone line induced by termite activity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Colin, F.; Gurarie, E.; Bourles, D.; Braucher, R.; Brown, E.; Anan, R.; Gilkes, R.; Meunier, J. D.; Varajao, C.</p> <p>2001-12-01</p> <p>The aim of this study is to understand the genesis of a stoneline sequence located at the border of the Yilgarn Craton in southwest Austrtalia. The sequence was selected because a well-defined line of siliceous pebbles traces the limit between a typical tropical saprolite and a soil almost entirely composed of termite nests, providing an opportunity to study the role of biological processes in stoneline genesis. A roadcut along the Boyup Brook Road provided the opportunity to examine and sample a 100 m wide section of weathering mantle developed on a gently sloping hill. The sequence consists, from base to top, of three main weathering layers: a gneiss- and schist-inherited yellow saprolite that includes subvertical quartz veins ; a 10 to 20 cm thick stone line composed primarily of angular quartz pebble; and a 40 to 50 cm thick dark brown surficial soil rich in both active and dormant termite nests. The distribution of these layers does not vary significantly across the hill, but quartz rich veins are most abundant in the central part of the hill. Kaolinite and quartz are the major mineralogical components throughout the sequence. There is little variation in grain size distributions, other than a modest increase in the >63 micron fractions of surface samples due to termite activity (mixing of minerals with woody and grassy debris). Chemical and mineralogical analyses were used to characterise the weathering layers and to investigate the role of termite colonies. We determined the in situ produced <span class="hlt">10</span><span class="hlt">Be</span> contents of samples collected from a depth profile through the quartz-rich schist and of pebbles from the stoneline at distances up to 40 m from central quartz veins. The <span class="hlt">10</span><span class="hlt">Be</span> depth profile shows a simple exponential decrease with depth, consistent with attenuation of cosmic ray neutrons and erosion at a rate of 20 mMyr, consistent with rates of excavation by termites. The pebbles from the stoneline have nearly constant <span class="hlt">10</span><span class="hlt">Be</span> concentrations that are approximately</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Geomo.268...54S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Geomo.268...54S"><span id="translatedtitle">Long-term background denudation rates of southern and southeastern Brazilian watersheds estimated with cosmogenic <span class="hlt">10</span><span class="hlt">Be</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sosa Gonzalez, Veronica; Bierman, Paul R.; Fernandes, Nelson F.; Rood, Dylan H.</p> <p>2016-09-01</p> <p>In comparison to humid temperate regions of the Northern Hemisphere, less is known about the long-term (millennial scale) background rates of erosion in Southern Hemisphere tropical watersheds. In order to better understand the rate at which watersheds in southern and southeastern Brazil erode, and the relationship of that erosion to climate and landscape characteristics, we made new measurements of in situ produced <span class="hlt">10</span><span class="hlt">Be</span> in river sediments and we compiled all extant measurements from this part of the country. New data from 14 watersheds in the states of Santa Catarina (n = 7) and Rio de Janeiro (n = 7) show that erosion rates vary there from 13 to 90 m/My (mean = 32 m/My; median = 23 m/My) and that the difference between erosion rates of basins we sampled in the two states is not significant. Sampled basin area ranges between 3 and 14,987 km2, mean basin elevation between 235 and 1606 m, and mean basin slope between 11 and 29°. Basins sampled in Rio de Janeiro, including three that drain the Serra do Mar escarpment, have an average basin slope of 19°, whereas the average slope for the Santa Catarina basins is 14°. Mean basin slope (R2 = 0.73) and annual precipitation (R2 = 0.57) are most strongly correlated with erosion in the basins we studied. At three sites where we sampled river sand and cobbles, the <span class="hlt">10</span><span class="hlt">Be</span> concentration in river sand was greater than in the cobbles, suggesting that these grain sizes are sourced from different parts of the landscape. Compiling all cosmogenic <span class="hlt">10</span><span class="hlt">Be</span>-derived erosion rates previously published for southern and southeastern Brazil watersheds to date (n = 76) with our 14 sampled basins, we find that regional erosion rates (though low) are higher than those of watersheds also located on other passive margins including Namibia and the southeastern North America. Brazilian basins erode at a pace similar to escarpments in southeastern North America. Erosion rates in southern and southeastern Brazil are directly and positively related to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFMOS12A0264F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFMOS12A0264F"><span id="translatedtitle">Water Mass Distribution and Particle Flux in the Arctic Ocean From Dissolved <span class="hlt">10</span><span class="hlt">Be</span> and 9Be Concentrations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Frank, M.; Porcelli, D.; Andersson, P.; Halliday, A. N.; Kubik, P. W.; Hattendorf, B.; Guenther, D.</p> <p>2002-12-01</p> <p>The Arctic Ocean basin is confined by landmasses similar to the Mediterranean. There is only little deep water formed seasonally on the shelves of the Arctic Ocean despite the low temperatures. This is due to a freshwater lid at the surface which originates from the Arctic rivers. The deeper Arctic Ocean water masses can thus only be renewed at comparatively low rates through the only deep connection to the Atlantic Ocean, the Fram Strait. At the same time the biogenic particulate fluxes in the central Arctic Ocean are very low due to perennial sea ice cover and the organic matter produced in the surface waters is remineralised efficiently. Detrital particle fluxes from either eolian or riverine sources are also very low. We will present the first combined dissolved <span class="hlt">10</span><span class="hlt">Be</span> (cosmogenic) and 9Be (continental sources) depth profiles from water samples of the major deep basins of the Arctic Ocean collected during the Swedish Arctic Ocean 2001 expedition. Be is 5-10 times less particle-reactive than other previously investigated radionuclides such as Th or Pa and should therefore even at the relatively low Arctic Ocean renewal rates serve as a quasi-conservative tracer for different origins of water masses (Atlantic Ocean/Norwegian Sea, Pacific Ocean, Arctic Shelves). 9Be and Nd isotope analyses provide complementary information on the pathways of dissolved material originating from the Arctic continents. Results obtained ten years ago at similar locations as in our study indicated a uniform distribution of <span class="hlt">10</span><span class="hlt">Be</span> at low values of 500 +/- 100 atoms/g suggesting restricted input and efficient homogenisation. In contrast, our new results show that in 2001 the inflowing waters from the Atlantic are traced by <span class="hlt">10</span><span class="hlt">Be</span> concentrations of up to 1100 atoms/g. In addition, the surface concentrations vary considerably. It will be discussed wether this is a consequence of a seasonal/decadal variability in the distribution of surface water masses, which has been deduced from oceanographic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFMPP31C2264L&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFMPP31C2264L&link_type=ABSTRACT"><span id="translatedtitle">Identifying signals of Late Pleistocene climate change from cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> chronologies of moraines in the western U.S.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Laabs, B. J. C.; Licciardi, J. M.; Leonard, E. M.; Munroe, J. S.</p> <p>2015-12-01</p> <p>Cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> exposure dating has become the most widely applied method of developing ages of terminal moraines in the western U.S. Advances in the precision of analytical measurements along with a more accurate understanding of spatial and temporal variations in the production of in situ <span class="hlt">10</span><span class="hlt">Be</span> have improved the accuracy of cosmogenic exposure dating of moraines. Such improvements afford more accurate assessment of the impact of regional and global-scale climate changes of the Late Pleistocene on glaciation in the western U.S. A great number of new and recalculated cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> exposure ages of moraines are considered here to identify the most probable drivers of changes in ice extent at the end of the last glacial period. The last Pleistocene glaciation culminated in the western U.S. during marine oxygen isotope stage 2, before or during the onset of the global Last Glacial Maximum at ca. 26.5 ka. Terminal moraine abandonment in several ranges corresponds to the end of the Last Glacial Maximum at ca. 19.0 ka. This observation indicates that most mountain glaciers started retreating in step with the decline of global ice volume, and possibly in response to rising insolation at northern middle latitudes. In some regions, such as the Northern Rocky Mountains and the Great Basin, mountain glaciers apparently advanced to or persisted near their maximum terminus positions well after the start of global deglaciation, during the interval of the Oldest Dryas/Heinrich Stadial 1 (ca. 19.0-14.6 ka). Although changes in atmospheric circulation and precipitation patterns during this time likely affected mountain glacier extent, rapid ice retreat commenced in nearly all settings by 17.0-16.0 ka. This indication of warming prior to the onset of the Bølling-Allerød interval at ca. 14.6 ka is consistent with records from elsewhere at northern middle latitudes, and supports the hypothesis that warming of the region was in phase with a global rise in atmospheric CO2. This</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015GeoRL..42.2759F&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015GeoRL..42.2759F&link_type=ABSTRACT"><span id="translatedtitle">The impact of geomagnetic spikes on the production rates of cosmogenic 14C and <span class="hlt">10</span><span class="hlt">Be</span> in the Earth's atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fournier, Alexandre; Gallet, Yves; Usoskin, Ilya; Livermore, Philip W.; Kovaltsov, Gennady A.</p> <p>2015-04-01</p> <p>We seek corroborative evidence of the geomagnetic spikes detected in the Near East ca. 980 BC and 890 BC in the records of the past production rates of the cosmogenic nuclides 14C and <span class="hlt">10</span><span class="hlt">Be</span>. Our forward modeling strategy rests on global, time-dependent, geomagnetic spike field models feeding state-of-the-art models of cosmogenic nuclide production. We find that spike models with an energy budget in line with presently inferred large-scale flow at Earth's core surface fail to produce a visible imprint in the nuclide record. Spike models able to reproduce the intensity changes reported in the Near East require an unaccountably high-magnitude core flow, yet their computed impact on cosmogenic isotope production rates remains ambiguous. No simple and unequivocal agreement is obtained between the observed and modeled nuclide records at the epochs of interest. This indicates that cosmogenic nuclides cannot immediately be used to confirm the occurrence of these two geomagnetic spikes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016QSRv..147...59C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016QSRv..147...59C"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> dating reveals early-middle Holocene age of the Drygalski Moraines in central West Greenland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cronauer, Sandra L.; Briner, Jason P.; Kelley, Samuel E.; Zimmerman, Susan R. H.; Morlighem, Mathieu</p> <p>2016-09-01</p> <p>We reconstruct the history of the Greenland Ice Sheet margin on the Nuussuaq Peninsula in central West Greenland through the Holocene using lake sediment analysis and cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> exposure dating of the prominent Drygalski Moraines. Erratics perched on bedrock outboard of the Drygalski Moraines constrain local deglaciation to ∼9.9 ± 0.6 ka (n = 2). Three Drygalski Moraine crests yield mean <span class="hlt">10</span><span class="hlt">Be</span> ages of 8.6 ± 0.4 ka (n = 2), 8.5 ± 0.2 ka (n = 3), and 7.6 ± 0.1 ka (n = 2) from outer to inner. Perched erratics between the inner two moraines average 7.8 ± 0.1 ka (n = 2) and are consistent with the moraine ages. Sediments from a proglacial lake with a catchment area extending an estimated 2 km beneath (inland of) the present ice sheet terminus constrain an ice sheet minimum extent from 5.4 ka to 0.6 ka. The moraine chronology paired with the lake sediment stratigraphy reveals that the ice margin likely remained within ∼2 km of its present position from ∼9.9 to 5.4 ka. This unexpected early Holocene stability, preceded by rapid ice retreat and followed by minimum ice extent between ∼5.4 and 0.6 ka, contrasts with many records of early Holocene warmth and the Northern Hemisphere summer insolation maximum. We suggest ice margin stability may instead be tied to adjacent ocean temperatures, which reached an optimum in the middle Holocene.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.9222L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.9222L"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> exposure dating of onset and timing of Neoglacial glacier advances in the Ecrins massif, French Alps</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Le Roy, Melaine; Deline, Philip; Carcaillet, Julien</p> <p>2013-04-01</p> <p>Alpine glaciers are known to be highly sensitive to change in temperature and precipitation on decadal to centennial time scales. For two decades, numerous studies on Holocene climate revealed a period marked by abrupt cold reversals (e.g. 8.2 ka event) with increasing frequency and magnitude after the Holocene Climatic Optimum, during the so-called Neoglacial period (roughly the last 4 ka). State-of-the-art studies indicate that largest alpine glaciers failed to exceed their Little Ice Age (LIA) extent during these LIA Type-Events, unlike certain smaller glaciers. In the French Alps, very few investigations were conducted to date on Holocene glacier variability. Almost all studies focused on the most glacierized area: the Mont Blanc massif, where suitable organic remains to apply radiocarbon dating and dendrochronology are available. Other glacierized massifs are poorly studied, without any Holocene/Neoglacial glacier chronology up to now. Here, we present the results of a study focusing on six glacier forefields distributed in the Ecrins massif. Detailed geomorphological mapping and in-situ produced <span class="hlt">10</span><span class="hlt">Be</span> dating were carried on multi-crested so-called "LIA composite moraines". The targeted ridges are located in distal position with respect to late LIA drift in order to identify Holocene cold pulses that have led to (or slightly exceeded) LIA-like glacier extent. The 35 <span class="hlt">10</span><span class="hlt">Be</span> ages obtained revealed that the onset of Neoglacial occurred at ~4.2 ka, and that at least two other advances were recorded at ~3.3 ka and ~0.85 ka. One site has yielded a nearly complete Neoglacial record as four discrete events have been dated. These results highlight the potential of lateral moraine ridge stratigraphy which could yield accurate record when sufficiently preserved, but also the different preservation of landforms along the glacier margin which could censor the record.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Geomo.224...55P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Geomo.224...55P"><span id="translatedtitle">Grain-size dependent concentration of cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> and erosion dynamics in a landslide-dominated Himalayan watershed</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Puchol, Nicolas; Lavé, Jérôme; Lupker, Maarten; Blard, Pierre-Henri; Gallo, Florian; France-Lanord, Christian</p> <p>2014-11-01</p> <p>For documenting recent or Late Quaternary erosion rates at the scale of a small watershed, or even an entire mountain range, the use of in-situ terrestrial cosmogenic nuclides (TCN), such as <span class="hlt">10</span><span class="hlt">Be</span>, in river sediments has become widespread over the last decade. In mountainous settings, however, landslides may induce a two-fold complication in the cosmogenic nuclide budget. First, they may episodically deliver large amounts of sediment with low TCN concentrations to the river channel. Second, they may generate a grain-size-concentration dependence in these sediments. However, studies that have explored grain-size dependence in landslide-dominated areas have reached differing conclusions and the underlying mechanisms remain poorly understood. The present study focuses on the Khudi Khola river basin, a small drainage basin in the central Himalayas. The area is characterized by steep slopes, heavy rainfall, and high sediment production rates. Importantly, the watershed contains a large area of active landsliding. In-situ <span class="hlt">10</span><span class="hlt">Be</span> was analyzed in sediments of grain sizes ranging from 75 μm to ~ 4 cm, collected from five locations: upstream, downstream, and in the small tributaries which drain the landslides. In all sampling locations, including those situated upstream of the landslides, the finest grains (75-250 μm) are two to four times more concentrated in <span class="hlt">10</span><span class="hlt">Be</span> than the largest clasts (> 4.7 mm). We developed a numerical slope model which includes a low level of background soil erosion and episodic denudation from large mass-wasting events. We then introduced a coarsening of average grain-size with soil-depth to the model. Our simulation shows that the data available for this valley are compatible with a scenario in which landslides deliver coarse grains to the channel that are less concentrated in TCN and have deeper provenance. Best-fit estimates of the model parameters suggest recurrence times of 3000 to 9000 years for a major landslide on the same slope, and mean long</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Geomo.206..107E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Geomo.206..107E"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> exposure age chronology of the last glaciation in the Krkonoše Mountains, Central Europe</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Engel, Zbyněk; Braucher, Régis; Traczyk, Andrzej; Laetitia, Léanni; AsterTeam</p> <p>2014-02-01</p> <p>A new chronology of the last glaciation is established for the Krkonoše (Giant) Mountains, Central Europe, based on in-situ produced <span class="hlt">10</span><span class="hlt">Be</span> in moraine boulders. Exposure ages and Schmidt Hammer rebound values obtained for terminal moraines on the northern and southern flank of the mountains suggest that the oldest preserved moraines represent early phases of the Last Glacial Maximum (LGM). Large moraines at the outlet of the Snowy Cirques (Śnieżne Kotły) and in the middle part of the Úpa (Obří důl) trough were deposited around 21 ka while a series of smaller moraines above the LGM deposits represent readvances that occurred no later than 18.1 ± 0.6 ka, 15.7 ± 0.5 ka, 13.5 ± 0.5 ka and 12.9 ± 0.7 ka. An exposure age of 13.8 ± 0.4 ka obtained for protalus ramparts at the foot of the Úpská jáma Cirque headwall indicates that glaciers advanced only in north- to east-facing cirques during the Lateglacial. The last glacier fluctuation was synchronous with the Younger Dryas cold event. The timing of local glacier advances during the last glacial episode correlates with the late Weichselian glacier phases in the Alps and in the Bavarian/Bohemian Forest.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012Tecto..31.2017C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012Tecto..31.2017C"><span id="translatedtitle">Paleoseismology of the Mejillones Fault, northern Chile: Insights from cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> and optically stimulated luminescence determinations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>CortéS A., J.; GonzáLez L., Gabriel; Binnie, S. A.; Robinson, R.; Freeman, S. P. H. T.; Vargas E., G.</p> <p>2012-04-01</p> <p>We have undertaken the first paleoseismological study on an upper plate fault in Chile. The selected structure was the Mejillones Fault, which is marked by a conspicuous fault-scarp. Using cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> and OSL dating and detailed sedimentary logging of trenches, we have constrained the abandonment of two alluvial surfaces by fault activity at ca. 35 ka and ca.14 ka. Based on stratigraphic observation we characterized the fault evolution in four intervals over the last ca. 35 ka. During the first three intervals the fault had a steady slip rate of 0.61 ± 0.26 m/ka. The fourth interval is delineated by the last vertical fault slip and the accumulation of un-deformed hillslope deposits after ca. 3.3 ka and has a slip rate of 0.22 ± 0.06 m/ka. The younger surface abandonment was caused by two Mw ˜ 7 paleoearthquakes with a recurrence interval of 5.0 ± 3.5 ka. The third interval is characterized by the interaction of hillslope deposits and aseismic slip and/or centimeter scale seismic slip events. At ca. 3.5 ka, a last large (Mw ˜ 6.6) earthquake took place. The recurrence intervals of large (Mw > 8.5) subduction earthquakes do not appear to be the same as the recurrence intervals of the Mw ˜ 7 events on the upper plate Mejillones Fault.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/576328','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/576328"><span id="translatedtitle">Weathering histories of Chinese loess deposits based on uranium and thorium series nuclides and cosmogenic {sup <span class="hlt">10</span>}<span class="hlt">Be</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gu, Z.Y. |; Lal, D.; Liu, T.S.</p> <p>1997-12-01</p> <p>The long, continuous deposition of dust in the Chinese loess plateau offers an unique opportunity to study the nature of soil weathering in a wide range of climatic conditions. In this paper we report on measurements of concentrations of U- and Th-series nuclides and of major cations in 150 loess and paleosol samples from five sites, going back 2.5 Ma. Using the results for {sup <span class="hlt">10</span>}<span class="hlt">Be</span> concentrations in these soils, we determined the absolute amounts of water added to several soil units and obtained: (1) first-order leaching constants for U and several cations and (2) the compositions of the soils contributing to the dust-source regions and of the dust at deposition. Further, based on analyses of {sup 230}Th in soils deposited in the past ca. 140 ka, we determined when the soils weathered in the source regions. We conclude that most of the weathering in the dust-source regions may have occurred during the interglacials. 34 refs., 8 figs., 2 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17080088','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17080088"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> evidence for the Matuyama-Brunhes geomagnetic reversal in the EPICA Dome C ice core.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Raisbeck, G M; Yiou, F; Cattani, O; Jouzel, J</p> <p>2006-11-01</p> <p>An ice core drilled at Dome C, Antarctica, is the oldest ice core so far retrieved. On the basis of ice flow modelling and a comparison between the deuterium signal in the ice with climate records from marine sediment cores, the ice at a depth of 3,190 m in the Dome C core is believed to have been deposited around 800,000 years ago, offering a rare opportunity to study climatic and environmental conditions over this time period. However, an independent determination of this age is important because the deuterium profile below a depth of 3,190 m depth does not show the expected correlation with the marine record. Here we present evidence for enhanced <span class="hlt">10</span><span class="hlt">Be</span> deposition in the ice at 3,160-3,170 m, which we interpret as a result of the low dipole field strength during the Matuyama-Brunhes geomagnetic reversal, which occurred about 780,000 years ago. If correct, this provides a crucial tie point between ice cores, marine cores and a radiometric timescale. PMID:17080088</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1815850C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1815850C"><span id="translatedtitle">U-Th and <span class="hlt">10</span><span class="hlt">Be</span> constraints on sediment recycling in proglacial settings, Lago Buenos Aires, Patagonia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cogez, Antoine; Herman, Frédéric; Pelt, Eric; Norton, Kevin; Darvill, Christopher; Christl, Marcus; Morvan, Gilles; Reuschlé, Thierry; Chabaux, François</p> <p>2016-04-01</p> <p>The sedimentary cycle includes the formation by erosion of rocks, transport and deposition. While erosion and deposition can be documented, the history of sediments between the time it is extracted from the rocks and ultimately deposited into basins remains a major challenge. However, the mechanism of transfer and alteration of the sediments during transport plays a key role in the evolution of basins, feedbacks between erosion and climate, and glacial-interglacial variability of sediment transport and weathering. This is particularly true in proglacial settings because large overdeepenings, in particular, are potential sediment traps for which the efficiency at evacuating those sediments is largely unknown. The Lago Buenos Aires moraines in Patagonia are particularly interesting because they are imbricated from the older in the outer part to the younger in the inner part of the system. We sampled fine grained sediments from these moraines and measured U-Th isotopes in the 4-50 μm silicate fraction. Deposition ages were refined using <span class="hlt">10</span><span class="hlt">Be</span> exposure ages. We show first that the comminution ages model can be improved by measuring also Th isotopes, from which weathering rates can be deduced. Moreover we show from our data that there is a time lag of 300 kyr on average between erosion and deposition in the moraine. This could be attributed to the long residence time of sediments in the lake overdeepening. This conclusion raises perspectives about the transport times and dynamic of the sediments during a whole sedimentary cycle, and the subsequent effect on weathering. This conclusion could also contradict some assumptions commonly made for our erosion rates/sediment fluxes reconstructions based on river sediments analysis, in recently deglaciated catchments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.T24B..01F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.T24B..01F"><span id="translatedtitle">Rate of fluvial incision in the Central Alps constrained through joint inversion of detrital <span class="hlt">10</span><span class="hlt">Be</span> and thermochronometric data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fox, M.; Leith, K.; Bodin, T.; Balco, G.; Shuster, D. L.</p> <p>2015-12-01</p> <p>Catchment-wide cosmogenic nuclide concentration (CNCs) measurements of erosion rates have revolutionized the interpretation of processes responsible for generating mountainous landscapes. However, surface processes can vary within a single catchment, leading to spatial and temporal variations in erosion rates. This is particularly apparent for landscapes that have transient topographic features due to changes in tectonics or inherited glacial topography. Detrital thermochronometry provides a means to assess where modern sediment is derived as a function of elevation, and constrains the relative erosion rates across a catchment. To solve the corresponding inverse problem, we build on the Bayesian interpretation of probability of observing a detrital age (Avdeev et al., 2011) and use a reversible jump Markov chain Monte Carlo algorithm to sample both the parameter space and also the model complexity. Rivers within the Codera watershed of the Bergell Intrusion (Central European Alps) have incised into a glacial valley. We integrate constraints from detrital apatite fission track ages and detrital <span class="hlt">10</span><span class="hlt">Be</span> concentrations to interrogate the primary erosion processes shaping this Alpine landscape and constrain rates of erosion across the catchment. We find that modern erosion rates within most downstream portions of the landscape are too low to permit the inferred ˜500 m of incision during the most recent interglacial. Based on the spatial pattern of modern erosion rates, we predict that if the incised fluvial valley was formed solely during interglacial periods, incision is likely to have initiated almost 400,000 years BP. We explore the potential for this type of analysis to study inaccessible landscapes currently covered by ice. Avdeev, B., Niemi, N.A., Clark, M.K., 2011. Doing more with less: Bayesian estimation of erosion models with detrital thermochronometric data. Earth Planet. Sci. Lett. 305 (3), 385-395.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22267765','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22267765"><span id="translatedtitle">Use of Arrott plots to identify Néel temperature (T{sub N}) in metamagnetic Ni{sub 48}Co{sub 6}Mn{sub <span class="hlt">26</span>}<span class="hlt">Al</span>{sub 20} polycrystalline ribbons</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Singh, Rohit; Kumar Srivastava, Saurabh; Chatterjee, Ratnamala E-mail: rmala@physics.iitd.ac.in; Nigam, Arun K.; Khovaylo, Vladimir V.; Varga, Lajos K.</p> <p>2013-12-28</p> <p>(Ni{sub 48}Co{sub 6})Mn{sub <span class="hlt">26</span>}<span class="hlt">Al</span>{sub 20} polycrystalline ribbons with B2 structure at room temperature are investigated. Considering the presence of competing magnetic interactions, Arrott-plot analysis gives T{sub N} ∼ 170 K. A broad ferromagnetic-paramagnetic transition (T{sub C}) is observed at ∼200 K. H-T phase-diagram is used to validate the presence of competing exchange interactions that persist till very close to T{sub C}. Based on Néel theory, a cluster model is used to explain the presence of ferromagnetic and antiferromagnetic clusters in the sample. Formation of ferromagnetic clusters can be understood in terms of positive exchange interactions among the Mn atoms that are neighboring Co atoms located at Ni sites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Geomo.234..151P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Geomo.234..151P"><span id="translatedtitle">Erosion rates and landscape evolution of the lowlands of the Upper Paraguay river basin (Brazil) from cosmogenic <span class="hlt">10</span><span class="hlt">Be</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pupim, Fabiano do Nascimento; Bierman, Paul R.; Assine, Mario Luis; Rood, Dylan H.; Silva, Aguinaldo; Merino, Eder Renato</p> <p>2015-04-01</p> <p>The importance of Earth's low sloping areas in regard to global erosion and sediment fluxes has been widely and vigorously debated. It is a crucial area of research to elucidate geologically meaningful rates of land-surface change and thus the speed of element cycling on Earth. However, there are large portions of Earth where erosion rates have not been well or extensively measured, for example, the tropical lowlands. The Cuiabana lowlands are an extensive low-altitude and low-relief dissected metamorphic terrain situated in the Upper Paraguay river basin, central-west Brazil. Besides exposures of highly variable dissected metamorphic rocks, flat residual lateritic caps related to a Late Cenozoic planation surface dominate interfluves of the Cuiabana lowlands. The timescale over which the lowlands evolved and the planation surface developed, and the rate at which they have been modified by erosion, are poorly known. Here, we present measurements of in situ produced cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> in outcropping metamorphic bedrock and clastic-lateritic caps to quantify rates of erosion of the surface and associated landforms in order to better understand the Quaternary landscape evolution of these lowlands. Overall, slow erosion rates (mean 10 m/Ma) suggest a stable tectonic environment in these lowlands. Erosion rates vary widely between different lithologies (range 0.57 to 28.3 m/Ma) consistent with differential erosion driving regional landform evolution. The lowest erosion rates are associated with the low-relief area (irregular plains), where clastic-laterite (mean 0.67 m/Ma) and quartzite (mean 2.6 m/Ma) crop out, whereas the highest erosion rates are associated with dissection of residual hills, dominated by metasandstone (mean 11.6 m/Ma) and phyllite (mean 27.6 m/Ma). These data imply that the Cuiabana lowland is comprised of two dominant landform sets with distinct and different dynamics. Because the planation surface (mostly lowlands) is lowering and losing mass more</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.T33B2221G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.T33B2221G"><span id="translatedtitle">Paleoseismology of Upper Plate Faults in the Chilean Covergent Margin: Insights from <span class="hlt">10</span><span class="hlt">BE</span> and OSL Dating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gonzalez, G.; Cortes, J. A.; Binnie, S.; Robinson, R.; Toledo, C.</p> <p>2010-12-01</p> <p>The Chilean convergent margin is the locus of most of the largest subduction earthquakes recorded in history. Slip deficit along this plate boundary is absorbed by elastic deformation of the upper plate. Numerical models and geodetic data suggest a fully elastic behaviour of the overriding crust and that deformation is balanced between inter- and co-seismic phases earthquake cycle; thus, non permanent deformation should be expected. However,the topographic surface of the coastal area, especially in the arid northern region of Chile (18°-26°S), shows clear evidences of permanent deformation expressed as kilometric-long fault scarps produced by normal faults. It suggests that normal faulting is a regional-scale extended process characteristic of the near surface structure of the upper plate. Some unanswered, yet critical, questions in this plate boundary are the present activity of these faults and the causal relationship between them and the subduction earthquake cycle. In order to answer these questions we conducted a paleoseismological project aimed at understanding the most recent activity of the upper plate faults in northern Chile. Here, we present the first results of two main faults located nearby the city of Antofagasta and the Mejillones Peninsula. One of these faults corresponds to the main strand of the Atacama Fault System whereas the other is the Mejillones Fault. At least 18 trenches were excavated for paleoseismological logging across these faults. OSL samples were extracted from wedge shaped colluvium and <span class="hlt">10</span><span class="hlt">Be</span> exposures ages were determined in alluvial surfaces displaced by the faults. Our results indicate that fault scarps were formed during Late Pleistocene-Holocene with a fault slip rate of 0.3 to 0.6 m/ky. Furthermore, we demonstrated that these faults generated large Mw~7 earthquakes with recurrence interval of many thousands years. In the Mejillones Fault, we determined that the elapsed time since the last large earthquake Mw~6.7 is ~3 ky BP</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoRL..43.9121B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..43.9121B"><span id="translatedtitle">The deep accumulation of <span class="hlt">10</span><span class="hlt">Be</span> at Utsira, southwestern Norway: Implications for cosmogenic nuclide exposure dating in peripheral ice sheet landscapes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Briner, Jason P.; Goehring, Brent M.; Mangerud, Jan; Svendsen, John Inge</p> <p>2016-09-01</p> <p>Cosmogenic nuclide exposure dating is a widely used method for constraining past ice sheet histories. We scrutinize a recently published data set of cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> data from erratic boulders in Norway used to constrain the deglaciation of the western Scandinavian Ice Sheet to 20 ka. Our model of the <span class="hlt">10</span><span class="hlt">Be</span> inventory in glacial surfaces leads us to conclude that the chronology may be afflicted by the deep subsurface accumulation of <span class="hlt">10</span><span class="hlt">Be</span> during long-lasting ice-free periods that resulted in <span class="hlt">10</span><span class="hlt">Be</span> ages >10% too old. We suggest that the majority of the dated erratic boulders contain a uniform level of inherited muon-produced <span class="hlt">10</span><span class="hlt">Be</span> and were derived from bedrock depths >2.5 m and most likely ~4 m. The implication of our finding is that for landscapes that experience long ice-free periods between brief maximum glacial phases, glacial erosion of >5 m is required to remove detectable traces of inherited <span class="hlt">10</span><span class="hlt">Be</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NIMPB.361..207F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..207F"><span id="translatedtitle">A preliminary study of direct <span class="hlt">10</span><span class="hlt">Be</span>2+ counting in AMS using the super-halogen anion BeF3-</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fu, Yun-Chong; Zhang, Li; Zhou, Wei-Jian; Zhao, Xiao-Lei; Wu, Zhen-Kun; Zhao, Guo-Qing; Liu, Qi; Lu, Xue-Feng; Zhao, Wen-Nian; Huang, Chun-Hai</p> <p>2015-10-01</p> <p>The key to effective <span class="hlt">10</span><span class="hlt">Be</span> measurements by AMS is to efficiently suppress the interference of the isobar 10B and at the same time optimize <span class="hlt">10</span><span class="hlt">Be</span> transmission. In this work, a new approach of measuring <span class="hlt">10</span><span class="hlt">Be</span> by AMS has been studied. It uses the super-halogen anion of beryllium, BeF3-, which inherently suppresses 10B interference by nearly 5 orders of magnitude because the accompanying BF3- anion is rarely formed. The resulting 10B suppression factor is not as high as that achieved with energy degrader foils, but the 10B and <span class="hlt">10</span><span class="hlt">Be</span> separation in the final ionization detector was found to result in sufficient total 10B suppression for <span class="hlt">10</span><span class="hlt">Be</span>2+ to be counted directly at ∼6 MeV energies. Although the stripping yield from <span class="hlt">10</span><span class="hlt">Be</span>F3- to <span class="hlt">10</span><span class="hlt">Be</span>2+ is not as large as that from <span class="hlt">10</span><span class="hlt">Be</span>O-, this inefficiency is compensated by avoiding the reduction in transmission due to charge fraction splitting and optical transmission losses after the degrader foil. This paper summarizes our first observation of the direct <span class="hlt">10</span><span class="hlt">Be</span>2+ counting approach using the 3 MV multi-element system at the Xi'an AMS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000NIMPB.172..112S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000NIMPB.172..112S"><span id="translatedtitle">PRIME lab AMS performance, upgrades and research applications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sharma, P.; Bourgeois, M.; Elmore, D.; Granger, D.; Lipschutz, M. E.; Ma, X.; Miller, T.; Mueller, K.; Rickey, F.; Simms, P.; Vogt, S.</p> <p>2000-10-01</p> <p>The Purdue Rare Isotope Measurement Laboratory (PRIME Lab) is a dedicated research and service facility for AMS that provides the scientific community with timely, reliable and high quality chemical processing (~600 samples/year) and AMS measurements (~3000 samples/year) of <span class="hlt">10</span><span class="hlt">Be</span>, 14C, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, 41Ca and 129I. The AMS system is based on an upgraded FN (7 MV) tandem accelerator that has recently been modified to improve performance. The precision is 1% for 14C and it is 3-5% for the other nuclides for radioisotope/stable isotope ratios at the 10-12 levels. System background for <span class="hlt">10</span><span class="hlt">Be</span>, 14C, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span> and 41Ca is 1-10×10-15 while for 129I the natural abundance limits it to 20×10-15. Research is being carried out in Earth, planetary, and biomedical sciences. Geoscience applications include determination of exposure ages of glacial moraines, volcanic eruptions, river terraces, and fault scarps. Burial histories of sand are being determined to decipher the timing of human expansion and climatic history. Environmental applications are tracing the release of radioactivity from nuclear fuel reprocessing plants, water tracing, and neutron dosimetry. The applications using meteoric nuclides are oil field brines, sediment subduction, radiocarbon dating, and groundwater <span class="hlt">36</span><span class="hlt">Cl</span> mapping. Radionuclide concentrations are also determined in meteorites and tektites for deciphering space and terrestrial exposure histories.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1211532P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1211532P"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> in ice at high resolution: Solar activity and climate signals observed and GCM-modeled in Law Dome ice cores</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pedro, Joel; Heikkilä, Ulla; van Ommen, T. D.; Smith, A. M.</p> <p>2010-05-01</p> <p>Changes in solar activity modulate the galactic cosmic ray flux, and in turn, the production rate of <span class="hlt">10</span><span class="hlt">Be</span> in the earth's atmosphere. The best archives of past changes in <span class="hlt">10</span><span class="hlt">Be</span> production rate are the polar ice cores. Key challenges in interpreting these archives as proxies for past solar activity lie in separating the useful solar activity (or production) signal from the interfering meteorological (or climate) signal, and furthermore, in determining the atmospheric source regions of <span class="hlt">10</span><span class="hlt">Be</span> deposited to the ice core site. In this study we use a new monthly resolution composite <span class="hlt">10</span><span class="hlt">Be</span> record, which spans the past decade, and a general circulation model (ECHAM5-HAM), to constrain both the production and climate signals in <span class="hlt">10</span><span class="hlt">Be</span> concentrations at the Law Dome ice core site, East Antarctica. This study differs from most previous work on <span class="hlt">10</span><span class="hlt">Be</span> in Antarctica due to the very high sample resolution achieved. This high resolution, through a time period where accurate instrumental measurements of solar activity and climate are available, allows us to examine the response of <span class="hlt">10</span><span class="hlt">Be</span> concentrations in ice to short-term (monthly to annual) variations in solar activity, and to short-term variations in climate, including seasonality. We find a significant correlation (r2 = 0.56, P < 0.005, n = 92) between observed <span class="hlt">10</span><span class="hlt">Be</span> concentrations and solar activity (represented by the neutron counting rate). The most pervasive climate influence is a seasonal cycle, which shows maximum concentrations in mid-to-late-summer and minimum concentrations in winter. Model results show reasonable agreement with observations; both a solar activity signal and seasonal cycle in <span class="hlt">10</span><span class="hlt">Be</span> are captured. However, the modeled snow accumulation rate is too high by approximately 60%. According to the model, the main atmospheric source region of <span class="hlt">10</span><span class="hlt">Be</span> deposited to Law Dome is the 30-90°S stratosphere (~50%), followed by the 30-90°S troposphere (~30%). An enhancement in the fraction of <span class="hlt">10</span><span class="hlt">Be</span> arriving to Law Dome from the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010NIMPB.268..187K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010NIMPB.268..187K"><span id="translatedtitle">A new value for the half-life of <span class="hlt">10</span><span class="hlt">Be</span> by Heavy-Ion Elastic Recoil Detection and liquid scintillation counting</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Korschinek, G.; Bergmaier, A.; Faestermann, T.; Gerstmann, U. C.; Knie, K.; Rugel, G.; Wallner, A.; Dillmann, I.; Dollinger, G.; von Gostomski, Ch. Lierse; Kossert, K.; Maiti, M.; Poutivtsev, M.; Remmert, A.</p> <p>2010-01-01</p> <p>The importance of <span class="hlt">10</span><span class="hlt">Be</span> in different applications of accelerator mass spectrometry (AMS) is well-known. In this context the half-life of <span class="hlt">10</span><span class="hlt">Be</span> has a crucial impact, and an accurate and precise determination of the half-life is a prerequisite for many of the applications of <span class="hlt">10</span><span class="hlt">Be</span> in cosmic-ray and earth science research. Recently, the value of the <span class="hlt">10</span><span class="hlt">Be</span> half-life has been the centre of much debate. In order to overcome uncertainties inherent in previous determinations, we introduced a new method of high accuracy and precision. An aliquot of our highly enriched <span class="hlt">10</span><span class="hlt">Be</span> master solution was serially diluted with increasing well-known masses of 9Be. We then determined the initial <span class="hlt">10</span><span class="hlt">Be</span> concentration by least square fit to the series of measurements of the resultant <span class="hlt">10</span><span class="hlt">Be</span>/ 9Be ratio. In order to minimize uncertainties because of mass bias which plague other low-energy mass spectrometric methods, we used for the first time Heavy-Ion Elastic Recoil Detection (HI-ERD) for the determination of the <span class="hlt">10</span><span class="hlt">Be</span>/ 9Be isotopic ratios, a technique which does not suffer from difficult to control mass fractionation. The specific activity of the master solution was measured by means of accurate liquid scintillation counting (LSC). The resultant combination of the <span class="hlt">10</span><span class="hlt">Be</span> concentration and activity yields a <span class="hlt">10</span><span class="hlt">Be</span> half-life of T1/2 = 1.388 ± 0.018 (1 s, 1.30%) Ma. In a parallel but independent study (Chmeleff et al. [11]), found a value of 1.386 ± 0.016 (1.15%) Ma. Our recommended weighted mean and mean standard error for the new value for <span class="hlt">10</span><span class="hlt">Be</span> half-life based on these two independent measurements is 1.387 ± 0.012 (0.87%) Ma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.H53C1388R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.H53C1388R"><span id="translatedtitle">A New Approach for Estimating Background Rates of Erosion Using Concentration of Meteoric <span class="hlt">10</span>-<span class="hlt">Be</span> Adhered to River Sediment: Application to the Rapidly Eroding Waipaoa Basin, New Zealand</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reusser, L. J.; Bierman, P. R.; Pavich, M.; Finkel, R.</p> <p>2007-12-01</p> <p>New and existing data suggest that the concentration of atmospherically- produced, meteoric <span class="hlt">10</span>-<span class="hlt">Be</span> adhered to river sediment provides a proxy for basin-scale erosion rates. Although the widely applied method of analyzing in situ produced <span class="hlt">10</span>-<span class="hlt">Be</span> in river sediments has proven useful for estimating pre-anthropogenic rates of erosion in a variety of environments, there are lithologic limitation. In contrast, measuring the concentration of meteoric <span class="hlt">10</span>-<span class="hlt">Be</span> adhered to river sediment allows erosion rate analysis in landscapes underlain by quartz-deficient or fine-grained lithologies, as well as in basins where the concentration of quartz varies spatially. By assuming that basins are in an overall isotopic steady-state, that erosion is rapid enough that decay is negligible, and that the integrated delivery rate of <span class="hlt">10</span>-<span class="hlt">Be</span> from the atmosphere (D<span class="hlt">10</span>-<span class="hlt">Be</span>) can be estimated, basin-scale mass loss rates (Ms) can be solved by equating the <span class="hlt">10</span>-<span class="hlt">Be</span> flux in from the atmosphere with the flux of <span class="hlt">10</span>-<span class="hlt">Be</span> out of the basin on sediment (C<span class="hlt">10</span>-<span class="hlt">Be</span>) and expressed as sediment yield per unit area (Ys). Fin = Fout D<span class="hlt">10</span>-<span class="hlt">Be</span> * A = Ms * C<span class="hlt">10</span>-<span class="hlt">Be</span> Ms = (D<span class="hlt">10</span>-<span class="hlt">Be</span> * A)/ C<span class="hlt">10</span>-<span class="hlt">Be</span> Ys = D<span class="hlt">10</span>-<span class="hlt">Be</span> / C<span class="hlt">10</span>-<span class="hlt">Be</span> To validate this new approach, we examined the limited data that do exist and found reasonable correspondence between erosion rates estimated from meteoric <span class="hlt">10</span>-<span class="hlt">Be</span> concentrations and estimated by other means. As a first application, we use meteoric <span class="hlt">10</span>-<span class="hlt">Be</span> in river sediment to estimate basin-scale erosion rates from catchments within and near the mud-stone dominated Waipaoa River Basin draining the tectonically active east coast of New Zealand's North Island. Near total conversion of indigenous forest to pasture over the past century in the Waipaoa Basin has resulted in some of the most dramatic and widespread erosional features on the planet, and contemporary sediment yields that rank among the highest in the world (~7 million kg/(km2 * yr)). The amount of meteoric <span class="hlt">10</span>-<span class="hlt">Be</span> adhered to eight river sediment samples suggests that modern</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMEP22B..02F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMEP22B..02F"><span id="translatedtitle">Hillslope lowering rates and mobile-regolith residence times from in situ and meteoric <span class="hlt">10</span><span class="hlt">Be</span> analysis: Boulder Creek Critical Zone Observatory, Colorado</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Foster, M. A.; Anderson, R. S.; Wyshnytzky, C.; Ouimet, W. B.; Dethier, D. P.</p> <p>2014-12-01</p> <p>Mobile regolith is produced as weathered saprolite is entrained into the mobile layer. The rate of mobile-regolith production and its residence time on hillslopes shapes the topography and evolution of hillslopes. We calculate the production rate of mobile regolith and the mobile-regolith residence times on active hillslopes in Gordon Gulch, within the Boulder Creek Critical Zone Observatory (CZO), Colorado. We find mobile-regolith production rates (average 3.1 cm/ka) and residence times (average 10-20 ka) derived from both in situand meteoric methods agree. Lowering-rates derived from our study are also comparable to basin-averaged denudation rates for small basins in the Colorado Front Range (Dethier and Lazarus, 2006). In this study, we have measured both in situ and meteoric <span class="hlt">10</span><span class="hlt">Be</span> in saprolite and mobile regolith separately. We find that, on average, two-thirds of in situ <span class="hlt">10</span><span class="hlt">Be</span> is produced within saprolite, and that at least one-tenth of the meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories are stored in saprolite. In the case of in situ <span class="hlt">10</span><span class="hlt">Be</span>, this simply reflects the exponential fall-off in production rates through a thin mobile-regolith cover. In the case of meteoric <span class="hlt">10</span><span class="hlt">Be</span>, our calculations suggest that >40% of the meteoric <span class="hlt">10</span><span class="hlt">Be</span> deposition occurs within the saprolite. Most studies that utilize <span class="hlt">10</span><span class="hlt">Be</span> report residence times and soil-production rates based on concentrations in either the mobile regolith or saprolite; therefore, our <span class="hlt">10</span><span class="hlt">Be</span> data highlight the importance of clearly identifying mobile and immobile portions of the regolith, constraining its <span class="hlt">10</span><span class="hlt">Be</span> inventory, and use of consistent terminology for the mobile-layer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMEP33D..05N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMEP33D..05N"><span id="translatedtitle">Dual <span class="hlt">10</span><span class="hlt">Be</span> isotope systems constrain the source of sediment and rate of erosion for the tropical Barron River catchment, Queensland, Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nichols, K. K.; Bierman, P. R.; Reusser, L. J.; Portenga, E.; Matmon, A.; Rood, D. H.</p> <p>2010-12-01</p> <p>In order to understand source of sediment and rate of erosion for Barron River catchment, which heads on the Atherton Tablelands of northeast Australia, crosses the northern Queensland escarpment and drains into the Coral Sea, we collected fluvial sediment and measured both in situ and meteoric <span class="hlt">10</span><span class="hlt">Be</span> contents on the medium sand fraction. We collected fourteen samples from rivers and streams including large regional drainages and small tributaries. The upland basins are characterized by lower relief and less precipitation than the steeper and wetter escarpment basins. One sample is quartz sand from the Coral Sea beach at Yorkey's Knob, below the escarpment. Sand from the Barron River upstream of the escarpment integrates the upland basins and has an in situ <span class="hlt">10</span><span class="hlt">Be</span> concentration of 2.31±0.84 x105atoms/g and an erosion rate of 17.2 m/My (calculated using the CRONOS on-line calculator). This is similar to a major upland tributary (2.51±0.40 x105 atoms/g; 15.2 m/My) and two smaller upstream tributaries (20.5 m/My and 21.4 m/My). Escarpment streams have less in situ <span class="hlt">10</span><span class="hlt">Be</span> in their sediment (mean = 1.64±0.55 x 105 atoms/g, n=8) and higher basin area-weighted erosion rates (37.2 m/My). Based on the in situ measurements, the uplands are eroding at approximately half the rate of the escarpment basins. The beach sand has an in situ <span class="hlt">10</span><span class="hlt">Be</span> concentration (2.75±0.19 x 105 atoms/g) similar to the upland sediment suggesting that the source of beach sand is the larger but more slowly eroding Tablelands. In contrast, the meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations of Barron River sand-sized sediment collected above the escarpment is ~4 fold lower (2.55x107 atoms/g) than the average meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentration of the 8 escarpment samples (9.94±4.49 x107 atoms/g). This discrepancy cannot be explained by differences in annual average precipitation which ranges only from 1.9 to 2.3 m/yr but likely results from the deep mobility of meteoric <span class="hlt">10</span><span class="hlt">Be</span> in oxic Tableland soils. Considering meteoric <span class="hlt">10</span><span class="hlt">Be</span> as a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70021298','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70021298"><span id="translatedtitle">Linking the<span class="hlt">10</span><span class="hlt">Be</span> continental record of Lake Baikal to marine and ice archives of the last 50 ka: Implication for the global dust-aerosol input</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Aldahan, A.; Possnert, G.; Peck, J.; King, J.; Colman, S.</p> <p>1999-01-01</p> <p>We present here a <span class="hlt">10</span><span class="hlt">Be</span> profile from the continental sediments of Lake Baikal (the world's largest fresh water lake), which, for the first time, shows the ??? 40 ka <span class="hlt">10</span><span class="hlt">Be</span> enhancement and a pattern that strongly matches those from the marine and ice records for the last 50 ka. This finding provides a new horizon for global and regional correlation of continental archives. Additionally, our VADM-predicted <span class="hlt">10</span><span class="hlt">Be</span> production confirms and further strengthens a common global cause (geomagnetic field intensity) for the change in atmospheric <span class="hlt">10</span><span class="hlt">Be</span> over the last 50 ka. We also show that most of the <span class="hlt">10</span><span class="hlt">Be</span> inventory to the lake has been provided by riverine input, but with a significant addition from direct precipitation and dust-aerosol fallout. We estimate a higher dust-aerosol contribution of <span class="hlt">10</span><span class="hlt">Be</span> during the Holocene and interstadial stage 3 (22-50 ka) as compared with the glacial period (12-22 ka). Copyright 1999 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMEP52D..05W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMEP52D..05W"><span id="translatedtitle">Constraints on regolith formation and erosion rates at the Susquehanna Shale Hills Critical Zone Observatory, PA, determined using meteoric <span class="hlt">10</span><span class="hlt">Be</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>West, N.; Kirby, E.; Bierman, P. R.; Rood, D. H.</p> <p>2011-12-01</p> <p>New meteoric <span class="hlt">10</span><span class="hlt">Be</span> data from 73 samples of bulk regolith collected along north- and south-facing hillslopes at the Susquehanna Shale Hills Critical Zone Observatory (SSHO) provide first-order constraints on the timescales of regolith formation. The SSHO is located in the presently temperate climate zone of central Pennsylvania; however, sustained periglacial climate during the time of maximal extent of the Laurentide ice sheet (~19-21 ka) and deforestation during mid-19th Century charcoal production may have exerted significant influence on regolith production. Here, we quantify soil residence times and corresponding rates of regolith production and erosion on the north- and south-facing slopes at SSHO, using meteoric <span class="hlt">10</span><span class="hlt">Be</span> in samples of regolith collected at 25 locations along each hillslope from ridge top to toe slope. Hillslopes within the SSHO are relatively planar, but exhibit a pronounced asymmetry; north-facing slopes are steeper (~20°) than south-facing slopes (~15°). Meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations decrease systematically with depth at all 6 profile sites. Meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories are similar at the north and south ridgetop sites (1.89 ± 0.55 at/cm2 and 1.63 ± 0.41 at/cm2, respectively) and generally increase with position downslope. Assuming that the delivery of meteoric <span class="hlt">10</span><span class="hlt">Be</span> to regolith is balanced by its removal via erosion, the total meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories at the north and south ridgetops are consistent with soil <span class="hlt">10</span><span class="hlt">Be</span> residence times of 10.5 ± 3 ky and 9.1 ± 2 ky, and with steady lowering rates of ~ 16 m/My and ~ 19 m/My, respectively. Increases in meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories downslope are consistent with relatively slow creep, with transport velocities of 0.45 cm/y and 0.38 cm/y for the north and south hillslopes, respectively. Comparison of our results with previously-published estimates of regolith production rates inferred from U-series disequilibrium reveals that estimates of steady-state erosion calculated using meteoric <span class="hlt">10</span><span class="hlt">Be</span> are considerably</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMGP23A1286S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMGP23A1286S"><span id="translatedtitle">Authigenic <span class="hlt">10</span><span class="hlt">Be</span>/9Be Ratio Signatures of the Cosmogenic Nuclide Production Linked to Geomagnetic Dipole Moment Variation During and Since the Brunhes/Matuyama Boundary</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Simon, Q.; Thouveny, N.; Bourles, D. L.; Ménabréaz, L.; Valet, J. P.; Valery, G.; Choy, S.</p> <p>2015-12-01</p> <p>The atmospheric production rate of cosmogenic nuclides is linked to the geomagnetic dipole moment (GDM) by a non-linear inverse relationship. Large amplitude GDM variations associated with reversals and excursions can potentially be reconstructed using time variation of the cosmogenic beryllium-10 (<span class="hlt">10</span><span class="hlt">Be</span>) production recorded in ocean sediments. Downcore profiles of authigenic <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios (proxy of atmospheric <span class="hlt">10</span><span class="hlt">Be</span> production) in oceanic cores provide independent and additional records of the evolution of the geomagnetic intensity and complete previous information derived from relative paleointensity (RPI). Here are presented new authigenic <span class="hlt">10</span><span class="hlt">Be</span>/9Be results obtained from cores MD05-2920 and from the top of core MD05-2930 collected in the West Equatorial Pacific Ocean. Completing data of Ménabréaz et al. (2012, 2014), these results provide the first continuous <span class="hlt">10</span><span class="hlt">Be</span> production rate sedimentary record covering the last 800 ka. Along these cores, authigenic <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio peaks are recorded - within methodological errors - at the stratigraphic level of RPI lows. High-resolution chronologies (δ18O-derived) lead to interpret these peaks as successive global <span class="hlt">10</span><span class="hlt">Be</span> overproduction events triggered by geomagnetic dipole lows present in the PISO-1500 and Sint-2000 stacks. The largest amplitude <span class="hlt">10</span><span class="hlt">Be</span> production enhancement is synchronous to the very large decrease of the dipole field associated with the last polarity reversal (772 ka). It is consistent in shape and duration with the peak recorded in core MD90-0961 from the Maldive area (Indian Ocean) (Valet et al. 2014). Two significant <span class="hlt">10</span><span class="hlt">Be</span> production enhancements are coeval with the Laschamp (41 ka) and Icelandic basin (190 ka) excursions, while <span class="hlt">10</span><span class="hlt">Be</span> production peaks of lower amplitude correlate to other recognized excursions such as the Blake (120 ka), Pringle-Falls (215 ka), Portuguese Margin (290 ka), Big Lost (540 ka) among others. This study provides new data on the amplitude and timing of dipole field variations</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMPP33C1950D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMPP33C1950D"><span id="translatedtitle">Drivers of foraminiferal and bulk-sedimentary <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios in a marine sediment record offshore of sub-tropical Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Davies, M. H.; Abrajevitch, A.; Srncik, M.; Fifield, L. K.; De Deckker, P.; Heslop, D.; Roberts, A. P.</p> <p>2013-12-01</p> <p>Meteoric <span class="hlt">10</span><span class="hlt">Be</span> (half-life of ~1.5 My) is produced in the atmosphere via cosmic ray spallation of 16O, following which it is quickly transported to Earth's surface by precipitation. This process concentrates <span class="hlt">10</span><span class="hlt">Be</span> in the ocean, where it is thought to remain with a residence time of ~500-1000 years prior to export to the marine sedimentary record largely associated with sorption to the surface of settling clay particles. The bulk beryllium isotopic composition of marine clays hence reflects the convoluted factors of <span class="hlt">10</span><span class="hlt">Be</span> production and varying scavenging efficiency/terrigenous input. However, measurements of meteoric <span class="hlt">10</span><span class="hlt">Be</span>/9Be incorporated in the calcium carbonate tests of foraminifera (and hence presumably isolated from the dilution effects of sediment-bound terrigenous 9Be) may have the potential to provide useful chronological control for marine sediment records. Here we present <span class="hlt">10</span><span class="hlt">Be</span>/9Be results from a ~42 m-long sediment core collected off the NW coast of Australia (MD00-2361: 113°28.63‧E, 22°04.92‧S, 1805 m water depth). Measurements of δ18O on Globigerinoides ruber, supported by magnetostratigraphy, indicate that the record extends back >1.2 Ma. This independent chronology, in conjunction with excellent carbonate preservation at this site, allows preliminary evaluation of foraminiferal <span class="hlt">10</span><span class="hlt">Be</span> as a chronometer. We also evaluate the relationship between sedimentary <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratios, regional surface ocean conditions as inferred from the δ18O stratigraphy and low-resolution Globigerinoides ruber Mg/Ca ratios, as well as large-scale changes in regional fluvial input as reconstructed from high-resolution XRF scanning profiles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMEP43A0747W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMEP43A0747W"><span id="translatedtitle">Using meteoric <span class="hlt">10</span><span class="hlt">Be</span> to track soil erosion and transport within a forested watershed, Susquehanna Shale Hills Critical Zone Observatory, PA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>West, N.; Kirby, E.; Bierman, P. R.; Rood, D. H.</p> <p>2010-12-01</p> <p>This study presents new meteoric <span class="hlt">10</span><span class="hlt">Be</span> data from 30 hillslope and bedrock core samples, data which allow for estimation of soil residence times and inferred rates of soil erosion in the Susquehanna Shale Hills Critical Zone Observatory (CZO). The Shale Hills CZO is located in the temperate climate of central Pennsylvania and comprises a first-order watershed developed on a Fe-rich, organic-poor, Silurian-aged shale. Two major perturbations to the landscape have occurred at the Shale Hills CZO in the geologically recent past, including significant periglacial activity until the retreat of the Laurentide ice sheet (~15 ka) and deforestation during early colonial land-use. Meteoric <span class="hlt">10</span><span class="hlt">Be</span> depth profiles were measured from bulk soil samples (n=16) collected at three locations along a planar hill-slope on the southern ridge of the catchment, representing the ridge top, mid- and foot-slope; samples were amalgamated over 10 cm depth intervals to the base of the soil (depth to hand auger refusal). Soil and rock chip samples (n=14) were also collected and analyzed along a 24 m deep core drilled into the northern ridge top. Meteoric <span class="hlt">10</span><span class="hlt">Be</span> was extracted from each sample using a total fusion method and analyzed at Lawrence Livermore National Laboratory. All meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentration profiles show a declining trend with depth, with >50% of the <span class="hlt">10</span><span class="hlt">Be</span> held in the upper-most decimeters of the soil. Meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventories are high at the mid- and foot-slope sites, at 3.71 ± 0.02 x 10^10 at/cm^2 and 3.69 ± 0.02 x 10^10 at/cm^2, respectively. The ridge top site has a lower inventory of 1.90 ± 0.01 x 10^10 at/cm^2, while the meteoric <span class="hlt">10</span><span class="hlt">Be</span> inventory for soil at the deep core site (also on a ridge top) is 4.09 ± 0.07 x 10^9 at/cm^2. Bedrock samples from the core contain at least an additional 1.07 x 10^10 at/cm^2 <span class="hlt">10</span><span class="hlt">Be</span>. If we assume that soils sampled at the Shale Hills CZO formed in place, and that <span class="hlt">10</span><span class="hlt">Be</span> delivery has been constant over time (1.8 x 10^6 atoms/cm^2 x y) and balanced by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMEP53A3641M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMEP53A3641M"><span id="translatedtitle">Initial Test Determination of Cosmogenic Nuclides in Magnetite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matsumura, H.; Caffee, M. W.; Nagao, K.; Nishiizumi, K.</p> <p>2014-12-01</p> <p>Long-lived radionuclides, such as <span class="hlt">10</span><span class="hlt">Be</span>, <span class="hlt">26</span><span class="hlt">Al</span>, and <span class="hlt">36</span><span class="hlt">Cl</span>, are produced by cosmic rays in surficial materials on Earth, and used for determinations of cosmic-ray exposure ages and erosion rates. Quartz and limestone are routinely used as the target minerals for these geomorphological studies. Magnetite also contains target elements that produce abundant cosmogenic nuclides when exposed to the cosmic rays. Magnetite has several notable merits that enable the measurement of cosmogenic nuclides: (1) the target elements for production of cosmogenic nuclides in magnetite comprise the dominant mineral form of magnetite, Fe3O4; (2) magnetite can be easily isolated, using a magnet, after rock milling; (3) multiple cosmogenic nuclides are produced by exposure of magnetite to cosmic-ray secondaries; and (4) cosmogenic nuclides produced in the rock containing the magnetite, but not within the magnetite itself, can be separated using nitric acid and sodium hydroxide leaches. As part of this initial study, magnetite was separated from a basaltic sample collected from the Atacama Desert in Chili (2,995 m). Then Be, Al, Cl, Ca, and Mn were separated from ~2 g of the purified magnetite. We measured cosmogenic <span class="hlt">10</span><span class="hlt">Be</span>, <span class="hlt">26</span><span class="hlt">Al</span>, and <span class="hlt">36</span><span class="hlt">Cl</span> concentrations in the magnetite by accelerator mass spectrometry at PRIME Lab, Purdue University. Cosmogenic 3He and 21Ne concentrations of aliquot of the magnetite were measured by mass spectrometry at the University of Tokyo. We also measured the nuclide concentrations from magnetite collected from a mine at Ishpeming, Michigan as a blank. The <span class="hlt">10</span><span class="hlt">Be</span> and <span class="hlt">36</span><span class="hlt">Cl</span> concentrations as well as 3He concentration produce concordant cosmic ray exposure ages of ~0.4 Myr for the Atacama basalt. However, observed high <span class="hlt">26</span><span class="hlt">Al</span> and 21Ne concentrations attribute to those nuclides incorporation from silicate impurity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000NIMPB.172..790H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000NIMPB.172..790H"><span id="translatedtitle">Cosmogenic in situ production of radionuclides: Exposure ages and erosion rates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heisinger, B.; Nolte, E.</p> <p>2000-10-01</p> <p>Experimental data for the cosmogenic in situ production of radionuclides and its depth dependence are used for two applications, the determination of exposure ages and of erosion rates. Concentrations of the long-lived radionuclides <span class="hlt">10</span><span class="hlt">Be</span>, 14C and <span class="hlt">26</span><span class="hlt">Al</span> in quartz are presented as function of exposure age, depth before exposure and erosion rate after exposure. It is shown that the cosmogenic production before exposure can introduce important corrections to the representation without consideration of pre-exposure production. Depth profiles of <span class="hlt">10</span><span class="hlt">Be</span>, 14C and <span class="hlt">26</span><span class="hlt">Al</span> in quartz and sulfur, of <span class="hlt">36</span><span class="hlt">Cl</span> in K 2O, CaCO 3, granite and concrete and of 53Mn in Fe 2O 3 are given as function of erosion rate. Consequences to determinations of neutron fluences in Hiroshima are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70015578','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70015578"><span id="translatedtitle">Detection of erosion events using <span class="hlt">10</span><span class="hlt">Be</span> profiles: example of the impact of agriculture on soil erosion in the Chesapeake Bay area (U.S.A.)</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Valette-Silver, J. N.; Brown, L.; Pavich, M.; Klein, J.; Middleton, R.</p> <p>1986-01-01</p> <p><span class="hlt">10</span><span class="hlt">Be</span> concentration, total carbon and grain-size were measured in cores collected in undisturbed estuarine sediments of three tributaries of the Chesapeake Bay. These cores were previously studied by Davis [1] and Brush [2,3] for pollen content, age and sedimentation rate. In this work, we compare the results obtained for these various analyses. In the cores, we observed two increases in <span class="hlt">10</span><span class="hlt">Be</span> concentration concomitant with two major changes in the pollen composition of the sediments. These two pollen changes each correspond to well-dated agricultural horizons reflecting different stages in the introduction of European farming techniques [2]. In the Chesapeake Bay area, the agricultural development, associated with forest clearing, appears to have triggered the erosion, transport, and sedimentation into the river mouths of large quantities of <span class="hlt">10</span><span class="hlt">Be</span>-rich soils. This phenomenon explains the observed rise in the sedimentation rate associated with increases in agricultural land-use. ?? 1986.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996LPI....27..357F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996LPI....27..357F"><span id="translatedtitle">Cosmogenic-radionuclide Profile of the Mocs Meteorite Strewnfield</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferko, T. E.; Lipschutz, M. E.</p> <p>1996-03-01</p> <p>Cosmic-ray produced nuclides were measured in samples from eight pieces of the L5-6 chondrite Mocs from known locations in the strewnfield. We measured <span class="hlt">10</span><span class="hlt">Be</span> and <span class="hlt">26</span><span class="hlt">Al</span> in the bulk phase along with <span class="hlt">36</span><span class="hlt">Cl</span> in both the metal and silicate phases. Relationships of the activities of these radionuclides from various meteorite pieces in the Mocs strewnfield provide new insight into the association of meteorite fragments to each other in the pre-atmospheric parent body. Results suggest a >2pi irradiation for the Mocs meteoroid which was less than 1 meter in radius.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/449829','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/449829"><span id="translatedtitle">The Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Roberts, M.L.; Heikkinen, D.W.; Southon, J.R.; Proctor, I.D.</p> <p>1996-10-01</p> <p>CAMS operates an HVEC FN tandem accelerator for use in both basic research and technology development. The accelerator is operated under a distributed computer control system with sophisticated auto-scaling, beam flat-topping, archiving, and recall capabilities, which makes possible rapid and precise switching between experimental configurations daily. Using the spectrometer, the AMS group can routinely measure the isotopes {sup 3}H, {sup 9}Be, {sup <span class="hlt">10</span>}<span class="hlt">Be</span>, {sup 14}C, {sup <span class="hlt">26</span>}<span class="hlt">Al</span>, {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, {sup 41}Ca, and {sup 129}I at abundances as low as 1 part in 10{sup 16}.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014M%26PS...49..394L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014M%26PS...49..394L"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> content in clasts from fallout suevitic breccia in drill cores from the Bosumtwi impact crater, Ghana: Clues to preimpact target distribution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Losiak, Anna; Wild, Eva Maria; Michlmayr, Leonard; Koeberl, Christian</p> <p>2014-03-01</p> <p>Rocks from drill cores LB-07A (crater fill) and LB-08A (central uplift) into the Bosumtwi impact crater, Ghana, were analyzed for the presence of the cosmogenic radionuclide <span class="hlt">10</span><span class="hlt">Be</span>. The aim of the study was to determine the extent to which target rocks of various depths were mixed during the formation of the crater-filling breccia, and also to detect meteoric water infiltration within the impactite layer. <span class="hlt">10</span><span class="hlt">Be</span> abundances above background were found in two (out of 24) samples from the LB-07A core, and in none of five samples from the LB-08A core. After excluding other possible explanations for an elevated <span class="hlt">10</span><span class="hlt">Be</span> signal, we conclude that it is most probably due to a preimpact origin of those clasts from target rocks close to the surface. Our results suggest that in-crater breccias were well mixed during the impact cratering process. In addition, the lack of a <span class="hlt">10</span><span class="hlt">Be</span> signal within the rocks located very close to the lake sediment-impactite boundary suggests that infiltration of meteoric water below the postimpact crater floor was limited. This may suggest that the infiltration of the meteoric water within the crater takes place not through the aerial pore-space, but rather through a localized system of fractures.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014E%26PSL.385..190M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014E%26PSL.385..190M&link_type=ABSTRACT"><span id="translatedtitle">The geomagnetic dipole moment variation between 250 and 800 ka BP reconstructed from the authigenic <span class="hlt">10</span><span class="hlt">Be</span>/9Be signature in West Equatorial Pacific sediments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ménabréaz, Lucie; Thouveny, Nicolas; Bourlès, Didier L.; Vidal, Laurence</p> <p>2014-01-01</p> <p>The authigenic <span class="hlt">10</span><span class="hlt">Be</span>/9Be ratio, proxy of the cosmogenic radionuclide <span class="hlt">10</span><span class="hlt">Be</span> production rate in the atmosphere, was measured in sediments deposited in the West Equatorial Pacific (Gulf of Papua; 10°25 S; 146°15 E), in order to reconstruct the geomagnetic dipole moment variations in the 250-800 ka time interval, independently from paleomagnetic methods. The pelagic clayey-carbonate muds continuously deposited between marine isotope stages 8 and 20 were subsampled every 10 cm. The <span class="hlt">10</span><span class="hlt">Be</span> production rate record reconstructed for the 250-800 ka interval is described and compared over the same time interval with global paleomagnetic stacks (SINT-2000 and PISO-1500). The highlighted cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> overproductions appear to be triggered by the series of Geomagnetic Dipole Lows (GDL) that have occurred since the Brunhes-Matuyama reversal. Calibration using absolute values of the geomagnetic dipole moment drawn from a paleomagnetic database produces a new record of the dipole moment variations over the 250-800 ka time interval. The timing and amplitude of the GDL succession revealed by such records will contribute to improving knowledge of the geodynamo rhythms and rate of changes at millennial to million year scales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70020821','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70020821"><span id="translatedtitle">Determination of predevelopment denudation rates of an agricultural watershed (Cayaguas River, Puerto Rico) using in-situ-produced <span class="hlt">10</span><span class="hlt">Be</span> in river-borne quartz</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Brown, E.T.; Stallard, R.F.; Larsen, M.C.; Bourles, D.L.; Raisbeck, G.M.; Yiou, F.</p> <p>1998-01-01</p> <p>Accurate estimates of watershed denudation absent anthropogenic effects are required to develop strategies for mitigating accelerated physical erosion resulting from human activities, to model global geochemical cycles, and to examine interactions among climate, weathering, and uplift. We present a simple approach to estimate predevelopment denudation rates using in-situ-produced cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> in fluvial sediments. Denudation processes in an agricultural watershed (Cayaguas River Basin, Puerto Rico) and a matched undisturbed watershed (Icacos River Basin) were compared using <span class="hlt">10</span><span class="hlt">Be</span> concentrations in quartz for various size fractions of bed material. The coarse fractions in both watersheds bear the imprint of long subsurface residence times. Fine material from old shallow soils contributes little, however, to the present-day sediment output of the Cayaguas. This confirms the recent and presumably anthropogenic origin of the modern high denudation rate in the Cayaguas Basin and suggests that pre-agricultural erosional conditions were comparable to those of the present-day Icacos.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012SCPMA..55.2357W&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012SCPMA..55.2357W&link_type=ABSTRACT"><span id="translatedtitle">Effect of thermal cycling on the mechanical properties of Zr41Ti14Cu12.5Ni<span class="hlt">10</span><span class="hlt">Be</span>22.5 alloy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Xin; Shao, Yang; Gong, Pan; Yao, KeFu</p> <p>2012-12-01</p> <p>The effect of thermal cycling treatment on mechanical properties and thermal stability of a Zr41Ti14Cu12.5Ni<span class="hlt">10</span><span class="hlt">Be</span>22.5 bulk metallic glass is investigated. The metallic glassy samples are sealed into quartz tubes under high vacuum condition, and liquid nitrogen together with electric furnace are used to control a periodical temperature variation between -196°C and 150°C. The structure and properties of the tested samples for different thermal cycles have been examined by X-ray diffraction analysis, mechanical properties measurement and thermal analysis. It has been found that the structure and properties of the samples do not show a significant change even after 200 cycles, which suggests Zr41Ti14Cu12.5Ni<span class="hlt">10</span><span class="hlt">Be</span>22.5 alloy as having potential in aerospace environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/945141','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/945141"><span id="translatedtitle">Ab Initio Many-Body Calculations Of n-3H, n-4He, p-3,4He, And n-<span class="hlt">10</span><span class="hlt">Be</span> Scattering</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Quaglioni, S; Navratil, P</p> <p>2008-03-26</p> <p>We develop a new ab initio many-body approach capable of describing simultaneously both bound and scattering states in light nuclei, by combining the resonating-group method with the use of realistic interactions, and a microscopic and consistent description of the nucleon clusters. This approach preserves translational symmetry and Pauli principle. We present phase shifts for neutron scattering on {sup 3}H, {sup 4}He and {sup <span class="hlt">10</span>}<span class="hlt">Be</span> and proton scattering on {sup 3,4}He, using realistic nucleon-nucleon potentials. Our A = 4 scattering results are compared to earlier ab initio calculations. We demonstrate that a proper treatment of the coupling to the n-{sup <span class="hlt">10</span>}<span class="hlt">Be</span> continuum is essential to explain the parity-inverted ground state in {sup 11}Be.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Geomo.224..102N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Geomo.224..102N"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> constrains the sediment sources and sediment yields to the Great Barrier Reef from the tropical Barron River catchment, Queensland, Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nichols, Kyle K.; Bierman, Paul R.; Rood, Dylan H.</p> <p>2014-11-01</p> <p>Estimates of long-term, background sediment generation rates place current and future sediment fluxes to the Great Barrier Reef in context. Without reliable estimates of sediment generation rates and without identification of the sources of sediment delivered to the reef prior to European settlement (c. 1850), determining the necessity and effectiveness of contemporary landscape management efforts is difficult. Here, using the ~ 2100-km2 Barron River catchment in Queensland, Australia, as a test case, we use in situ-produced <span class="hlt">10</span><span class="hlt">Be</span> to derive sediment generation rate estimates and use in situ and meteoric <span class="hlt">10</span><span class="hlt">Be</span> to identify the source of that sediment, which enters the Coral Sea near Cairns. Previous model-based calculations suggested that background sediment yields were up to an order of magnitude lower than contemporary sediment yields. In contrast, in situ <span class="hlt">10</span><span class="hlt">Be</span> data indicate that background (43 t km- 2 y- 1) and contemporary sediment yields (~ 45 t km- 2 y- 1) for the Barron River are similar. These data suggest that the reef became established in a sediment flux similar to what it receives today. Since western agricultural practices increased erosion rates, large amounts of sediment mobilized from hillslopes during the last century are probably stored in Queensland catchments and will eventually be transported to the coast, most likely in flows triggered by rare but powerful tropical cyclones that were more common before European settlement and may increase in strength as climate change warms the south Pacific Ocean. In situ and meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations of Coral Sea beach sand near Cairns are similar to those in rivers on the Atherton Tablelands, suggesting that most sediment is derived from the extensive, low-gradient uplands rather than the steep, more rapidly eroding but beach proximal escarpment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMEP13F..05N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMEP13F..05N"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> constrains the sediment sources and sediment yields to the Great Barrier Reef from the tropical Barron River catchment, Queensland, Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nichols, K. K.; Bierman, P. R.; Rood, D. H.</p> <p>2014-12-01</p> <p>Estimates of long-term, background sediment generation rates place current and future sediment fluxes to the Great Barrier Reef in context. Without reliable estimates of sediment generation rates and without identification of the sources of sediment delivered to the reef prior to European settlement (c. 1850), determining the necessity and effectiveness of contemporary landscape management efforts is difficult. Using the ~2100-km2 Barron River catchment in Queensland, Australia, as a test case, we use in situ-produced <span class="hlt">10</span><span class="hlt">Be</span> to derive sediment generation rate estimates and use in situ and meteoric <span class="hlt">10</span><span class="hlt">Be</span> to identify the source of that sediment, which enters the Coral Sea near Cairns. Previous model-based calculations suggested that background sediment yields were up to an order of magnitude lower than contemporary sediment yields. In contrast, in situ <span class="hlt">10</span><span class="hlt">Be</span> data indicate that background (43 t km-2 y-1) and contemporary sediment yields (~45 t km-2 y-1) for the Barron River are similar. These data suggest that the reef became established in a sediment flux similar to what it receives today. Since western agricultural practices increased erosion rates, large amounts of sediment mobilized from hillslopes during the last century are probably stored in Queensland catchments and will eventually be transported to the coast, most likely in flows triggered by rare but powerful tropical cyclones that were more common before European settlement and may increase in strength as climate change warms the south Pacific Ocean. In situ and meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations of Coral Sea beach sand near Cairns are similar to those in rivers on the Atherton Tablelands, suggesting that most sediment is derived from the extensive, low-gradient uplands rather than the steep, more rapidly eroding but beach proximal escarpment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813734C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813734C"><span id="translatedtitle">Atmospheric production signal in <span class="hlt">10</span><span class="hlt">Be</span> from varved sediments of Lake Meerfelder Maar during the late glacial-early Holocene transition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Czymzik, Markus; Adolphi, Florian; Muscheler, Raimund; Brauer, Achim; Mekhaldi, Florian; Martin-Puertas, Celia; Tjallingii, Rik; Aldahan, Ala; Possnert, Göran</p> <p>2016-04-01</p> <p>Beryllium 10 concentrations (10Becon) were measured at 20-year resolution in annually laminated (varved) sediments of Lake Meerfelder Maar (western Germany) covering the late glacial-early Holocene transition 11310-13130 varve years before present. Comparing the 10Becon record to environmental proxy records from the same archive indicates that varying sediment accumulation and composition only slightly modify trends, but do not substantially influence multi-decadal to centennial 10Becon excursions. Corrected for potential environmental biases using multiple-regression analysis, the resulting 10Beatmosphere time-series likely represents an alternative mid-latitude <span class="hlt">10</span><span class="hlt">Be</span> production record, exhibiting broad similarities but also some differences to radionuclide records as 14C in tree rings and <span class="hlt">10</span><span class="hlt">Be</span> in polar ice cores. The preservation of the globally common atmospheric production signal in <span class="hlt">10</span><span class="hlt">Be</span> from varved lake sediments indicates the, to date, largely unexplored potential of these archives for the synchronization to other radionuclide records around the globe, complementing existing solar activity reconstructions and Sun-climate studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010E%26PSL.296..443S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010E%26PSL.296..443S"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> evidence for delayed acquisition of remanent magnetization in marine sediments: Implication for a new age for the Matuyama-Brunhes boundary</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Suganuma, Yusuke; Yokoyama, Yusuke; Yamazaki, Toshitsugu; Kawamura, Kenji; Horng, Chorng-Shern; Matsuzaki, Hiroyuki</p> <p>2010-08-01</p> <p>Fluxes of the meteoric cosmogenic radionuclide <span class="hlt">10</span><span class="hlt">Be</span> vary with changes in the incoming cosmic rays modulated by geomagnetic field intensity variations. The variability in the <span class="hlt">10</span><span class="hlt">Be</span> flux can be used to synchronize ice cores, as well as marine sediments, by comparison with the relative paleointensity variations of the geomagnetic field. However, lock-in of the paleomagnetic signal at some depth below the sediment-water interface in marine sediments through acquisition of a post-depositional remanent magnetization (PDRM) adds uncertainty to synchronization. Despite the long history of such studies, the magnitude of the PDRM lock-in depth remains controversial. In this article, we present clear evidence for a downward offset of the paleointensity minimum relative to the <span class="hlt">10</span><span class="hlt">Be</span> flux anomaly at the Matuyama-Brunhes (M-B) geomagnetic polarity boundary, which we interpret to result from a ˜ 15 cm PDRM lock in depth. This lock-in depth indicates that up to several tens of thousands years of age offset probably occurs when a paleomagnetic record is used for dating marine sediments, and the age of the M-B boundary should be revised to ca. 10 kyr younger, which is consistent with a younger ice core derived age of 770 ± 6 ka (2 σ). This cosmogenic age tuning strategy will contribute to refining paleomagnetic-based age models for marine sediments and identifying of lead-lag relationships for global abrupt environmental changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvC..91c4606L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvC..91c4606L"><span id="translatedtitle">Microscopic analysis of Be,1110 elastic scattering on protons and nuclei, and breakup processes of 11Be within the <span class="hlt">10</span><span class="hlt">Be</span> +n cluster model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lukyanov, V. K.; Kadrev, D. N.; Zemlyanaya, E. V.; Spasova, K.; Lukyanov, K. V.; Antonov, A. N.; Gaidarov, M. K.</p> <p>2015-03-01</p> <p>The density distributions of <span class="hlt">10</span><span class="hlt">Be</span> and 11Be nuclei obtained within the quantum Monte Carlo model and the generator coordinate method are used to calculate the microscopic optical potentials (OPs) and cross sections of elastic scattering of these nuclei on protons and 12C at energies E <100 MeV/nucleon. The real part of the OP is calculated using the folding model with the exchange terms included, while the imaginary part of the OP that reproduces the phase of scattering is obtained in the high-energy approximation. In this hybrid model of OP the free parameters are the depths of the real and imaginary parts obtained by fitting the experimental data. The well-known energy dependence of the volume integrals is used as a physical constraint to resolve the ambiguities of the parameter values. The role of the spin-orbit potential and the surface contribution to the OP is studied for an adequate description of available experimental elastic scattering cross-section data. Also, the cluster model, in which 11Be consists of a n -halo and the <span class="hlt">10</span><span class="hlt">Be</span> core, is adopted. Within the latter, the breakup cross sections of 11Be nucleus on 9Be,93Nb,181Ta , and 238U targets and momentum distributions of <span class="hlt">10</span><span class="hlt">Be</span> fragments are calculated and compared with the existing experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6924887','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6924887"><span id="translatedtitle">[sup 14]C and [sup <span class="hlt">10</span>]<span class="hlt">Be</span> evidence for no incursion of the Lake Michigan lobe in northern Illinois from ca. 170 to 25 ka</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Curry, B.B. ); Pavich, M.J. )</p> <p>1994-04-01</p> <p>Uncorrected [sup <span class="hlt">10</span>]<span class="hlt">Be</span> inventories of a 2.7 m-long section of core indicate surface exposure lasting 115 ka during development of the Sangamon Geosol and 30 ka for a soil complex developed in overlying loessial sediment (Robein Silt). The latter estimate is in agreement with [sup 14]C assays in the region. Taking into account the age of overlying late Wisconsin drift, the new data indicate an age of about 170 ka for the onset of Sangamon pedogenesis in northern Illinois. Previous to this study, there have been no numerical-age determinations for the start of the last interglacial in northern IL. The data confirm a previous hypothesis that the Lake Michigan Lobe did not invade IL contemporaneous with deposition of Roxana Silt, or during the other period of midcontinental loess deposition suggest by TL ages of ca. 70 to 85 ka. The core was collected immediately south of the IL-WI border (42[degree] 30 minutes N, 88[degree] 30 minutes W) near Hebron, IL. Buried by 14 m of late Wisconsin drift, and the interval assayed for [sup <span class="hlt">10</span>]<span class="hlt">Be</span> included 2.0 m of pedogenically-altered Illinoian sand and gravel, and 0.7 m of Wisconsin silt. One AMS [sup 14]C assay of carbonized fragments from the A-horizon of the Sangamon Geosol yielded an age of 38,500 [+-] 5,000 yr B.P.; conventional [sup 14]C ages for the overlying silt are from wood fragments (24,780 [times] 360 yr B.P.) and a bulk soil sample (26,030 [+-] 450 yr B.P.). The range of ages is typical for this stratigraphic sequence in IL. The [sup <span class="hlt">10</span>]<span class="hlt">Be</span> concentration in the lowest part of the silt is 600 atoms/gm. This value is three times greater than the concentration typical of calcareous Mississippi River valley loess and of the C-horizon of the Sangamon Geosol in the core. High concentration of [sup <span class="hlt">10</span>]<span class="hlt">Be</span> in the Robein Silt likely was caused by redeposition of [sup <span class="hlt">10</span>]<span class="hlt">Be</span>-rich B-horizon material eroded from soil profiles elsewhere in the paleobasin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016QSRv..138...31R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016QSRv..138...31R"><span id="translatedtitle">Chronology of glaciations in the Cantabrian Mountains (NW Iberia) during the Last Glacial Cycle based on in situ-produced <span class="hlt">10</span><span class="hlt">Be</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rodríguez-Rodríguez, Laura; Jiménez-Sánchez, Montserrat; Domínguez-Cuesta, María José; Rinterknecht, Vincent; Pallàs, Raimon; Bourlès, Didier</p> <p>2016-04-01</p> <p>The mountain ranges of the Iberian Peninsula preserve a valuable record of past glaciations that may help reconstruct past atmospheric circulation patterns in response to cooling events in the North Atlantic Ocean. Available chronologies for the glacial record of the Cantabrian Mountains, which are mainly based on radiocarbon and luminescence dating of glacial-related sediments, suggest that glaciers recorded their Glacial Maximum (GM) during MIS 3 and experienced a later Last Glacial Maximum (LGM) advance. This LGM extent is not established yet, preventing a fair correlation with available Cosmic Ray Exposure (CRE) based chronologies for the glacial record of the Pyrenees and the Sistema Central. We present a glacial reconstruction and a <span class="hlt">10</span><span class="hlt">Be</span> CRE chronology for the Porma valley, in the southern slope of the central Cantabrian Mountains. Glacial evidence at the lowest altitudes correspond to erratic boulders and composite moraines whose minimum <span class="hlt">10</span><span class="hlt">Be</span> CRE age of 113.9 ± 7.1 ka suggests that glaciers were at their maximum extent during MIS 5d, most likely in response to the minima in summertime insolation of the Last Glacial Cycle. Recessional moraines preserved within the glacial maximum limits allow the assessment of subsequent glacier advances or stagnations. The most remarkable advance took place prior to 55.7 ± 4.0 ka (probably at the end of MIS 4), consistently with minimum radiocarbon ages previously reported for lacustrine glacial-related deposits in the Cantabrian Mountains. A limited number of <span class="hlt">10</span><span class="hlt">Be</span> CRE ages from a composite moraine suggest a possible advance of the Porma glacier coeval with the global LGM; the glacier front attributed to the LGM would be placed within the margins of the previous GM like in the western Pyrenees. Erratic boulders perched on an ice-moulded bedrock surface provided a mean <span class="hlt">10</span><span class="hlt">Be</span> CRE age of 17.7 ± 1.0 ka, suggesting that part of the recessional moraine sequence corresponds to minor advances or stagnations of the glacier fronts</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013EGUGA..1510831C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013EGUGA..1510831C&link_type=ABSTRACT"><span id="translatedtitle">Extended record of <span class="hlt">10</span><span class="hlt">Be</span> at EPICA Dome C during the last 800 000 years and its synchronization with geomagnetic paleointensity variations from marine sediments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cauquoin, Alexandre; Raisbeck, Grant; Jouzel, Jean; Bard, Edouard; Aster Team</p> <p>2013-04-01</p> <p>Polar ice cores are exceptional archives that permit the reconstruction of many parameters (variations of temperature, atmospheric composition...) and the reconstitution of the past variations of the Earth climate and environment. They also give access to beryllium-10 (<span class="hlt">10</span><span class="hlt">Be</span>) fallout, an isotope of cosmogenic origin, created by the interaction of Galactic Cosmic Rays (GCR, constituted of high energy charged particles) with the upper atmosphere. The cosmic rays being modulated by solar activity and Earth's magnetic field intensity, the <span class="hlt">10</span><span class="hlt">Be</span> production is inversely related to the intensity of these two parameters. Most <span class="hlt">10</span><span class="hlt">Be</span> produced is quickly removed from the atmosphere (residence time in the stratosphere ~1-2 years) and, on the Antarctic plateau, falls mainly by dry deposition as aerosols. So, <span class="hlt">10</span><span class="hlt">Be</span> can be used as a proxy of paleointensity. It has allowed the improvement of ice cores chronologies thanks to absolute stratigraphic markers linked to excursions and inversions of the geomagnetic field such as the Laschamp excursion [1] or the Matuyama-Brunhes reversal [2, 3]. EPICA Dome C (75° 06' S, 123° 21' E) is a 3270 meter ice core drilled in East Antarctica in the framework of an international project. It offers a complete climate record over the last 800 000 years. As shown at the IPICS 2012 meeting, for the 355 - 800 ka period [4], a continuous high-resolution (11 cm) <span class="hlt">10</span><span class="hlt">Be</span> profile in this core can be synchronized with continuous variations of paleointensity (PISO-1500) recorded in marine sediments [5] in order to obtain a continuous relative chronology of climate proxies (δD and δ18O respectively) for these two reservoirs. Here, we extend this synchronization down to 269 ka, thus including termination IV and interstadial MIS 9. [1]. Raisbeck et al. (2007) Clim.Past, 3, 541 - 547. [2]. Raisbeck et al. (2006) Nature, 444, 82 - 84. [3]. Dreyfus et al. (2008) Earth and Planet. Sci. Lett., 274, 151 - 156. [4]. G.Raisbeck et al. (2012) IPICS Open Science Conference</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010AGUFMEP41C0711L&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010AGUFMEP41C0711L&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span>, OSL/IRSL Luminescence and 14C Cross-Dating of a Series of Abandoned Alluvial Surfaces Laterally Offset by the Dead Sea Fault, Jordan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Le Beon, M.; Jaiswal, M.; Al-Qaryouti, M.; Moumani, K.; Burr, G. S.; Chen, Y.; Klinger, Y.; Abdelghafoor, M.; Suppe, J.</p> <p>2010-12-01</p> <p>Active tectonics studies are often limited by the uncertainties in accurately and precisely dating Late Quaternary deposits, especially alluvial deposits that often lack organic matter datable by 14C method. This is the case along the Wadi Araba Fault (WAF), the southernmost segment of the Dead Sea Fault, which delineates the 1000-km long plate boundary between the Arabia plate and the Sinai sub-plate. Geodetic, geomorphic and geologic studies converge to a fault slip rate of 5 ± 2 mm/a. Yet, long-term Late Pleistocene slip rates cover a wide range due to large uncertainties, mostly related to the dispersion of <span class="hlt">10</span><span class="hlt">Be</span> cosmogenic radionuclide (CRN) ages. The maximum slip rate since ~100 ka is up to a value of 11 mm/a, possibly suggesting significant variations in fault activity with time. In order to reduce the uncertainty on the Late Pleistocene slip rate and draw further conclusions regarding the seismic behavior of the WAF, we targeted one of the sites previously investigated for detailed morphotectonic analysis and <span class="hlt">10</span><span class="hlt">Be</span> CRN dating and we apply other chronometers, such as Optically stimulated luminescence (OSL) dating on quartz and feldspar minerals, and 14C dating when possible. The site consists in an abandoned bajada composed of four alluvial surface levels, offset by the WAF. We extensively sampled the terraces F2 and F4, which are offset by 160 ± 8 m and 626 ± 37 m, respectively. Our samples are collected from ~50-cm deep pits on the top of the terraces. On F2, we collected one OSL sample downstream from the fault and two upstream, where land snail shells were also found. Preliminary OSL ages agree on ~8 ± 2 ka upstream, also consistent with a 14C date, whereas the OSL age downstream is much older, ~41 ± 4 ka. On F4, we collected three samples downstream from the fault and two upstream. Preliminary OSL ages cluster between ~32 ± 4 ka and ~46 ± 5 ka. Five of the OSL samples have been collected at a similar location to surficial cobbles for <span class="hlt">10</span><span class="hlt">Be</span>, both on</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016QSRv..148...54B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016QSRv..148...54B"><span id="translatedtitle">A cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> chronology for the local last glacial maximum and termination in the Cordillera Oriental, southern Peruvian Andes: Implications for the tropical role in global climate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bromley, Gordon R. M.; Schaefer, Joerg M.; Hall, Brenda L.; Rademaker, Kurt M.; Putnam, Aaron E.; Todd, Claire E.; Hegland, Matthew; Winckler, Gisela; Jackson, Margaret S.; Strand, Peter D.</p> <p>2016-09-01</p> <p>Resolving patterns of tropical climate variability during and since the last glacial maximum (LGM) is fundamental to assessing the role of the tropics in global change, both on ice-age and sub-millennial timescales. Here, we present a<span class="hlt">10</span><span class="hlt">Be</span> moraine chronology from the Cordillera Carabaya (14.3°S), a sub-range of the Cordillera Oriental in southern Peru, covering the LGM and the first half of the last glacial termination. Additionally, we recalculate existing <span class="hlt">10</span><span class="hlt">Be</span> ages using a new tropical high-altitude production rate in order to put our record into broader spatial context. Our results indicate that glaciers deposited a series of moraines during marine isotope stage 2, broadly synchronous with global glacier maxima, but that maximum glacier extent may have occurred prior to stage 2. Thereafter, atmospheric warming drove widespread deglaciation of the Cordillera Carabaya. A subsequent glacier resurgence culminated at ∼16,100 yrs, followed by a second period of glacier recession. Together, the observed deglaciation corresponds to Heinrich Stadial 1 (HS1: ∼18,000-14,600 yrs), during which pluvial lakes on the adjacent Peruvian-Bolivian altiplano rose to their highest levels of the late Pleistocene as a consequence of southward displacement of the inter-tropical convergence zone and intensification of the South American summer monsoon. Deglaciation in the Cordillera Carabaya also coincided with the retreat of higher-latitude mountain glaciers in the Southern Hemisphere. Our findings suggest that HS1 was characterised by atmospheric warming and indicate that deglaciation of the southern Peruvian Andes was driven by rising temperatures, despite increased precipitation. Recalculated <span class="hlt">10</span><span class="hlt">Be</span> data from other tropical Andean sites support this model. Finally, we suggest that the broadly uniform response during the LGM and termination of the glaciers examined here involved equatorial Pacific sea-surface temperature anomalies and propose a framework for testing the viability</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010JGRB..11511414L&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010JGRB..11511414L&link_type=ABSTRACT"><span id="translatedtitle">Early Holocene and Late Pleistocene slip rates of the southern Dead Sea Fault determined from <span class="hlt">10</span><span class="hlt">Be</span> cosmogenic dating of offset alluvial deposits</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Le BéOn, Maryline; Klinger, Yann; Al-Qaryouti, Mahmoud; MéRiaux, Anne-Sophie; Finkel, Robert C.; Elias, Ata; Mayyas, Omar; Ryerson, Frederick J.; Tapponnier, Paul</p> <p>2010-11-01</p> <p>Two sites located along the Wadi Araba Fault (WAF) segment of the Dead Sea Fault are targeted for tectonic-morphological analysis. <span class="hlt">10</span><span class="hlt">Be</span> cosmogenic radionuclide (CRN) dating of embedded cobbles is used to constrain the age of offset alluvial surfaces. At the first site a 48 ± 7 m offset alluvial fan, for which <span class="hlt">10</span><span class="hlt">Be</span> CRN model ages average 11.1 ± 4.3 ka, yield a slip rate of 5.4 ± 2.7 mm/a, with conservative bounds of 1.3-16.4 mm/a. At the second site the scattered distributions of the <span class="hlt">10</span><span class="hlt">Be</span> CRN ages from an offset bajada attest to the complex processes involved in sediment transport and emplacement. There, two offsets were identified. The 160 ± 8 m offset of an incised alluvial fan dated at 37 ± 5 ka shows a slip rate of 4.5 ± 0.9 mm/a, with a conservative minimum value of 3.2 mm/a. A larger offset, 626 ± 37 m, is derived from a prominent channel incised into the bajada. Cobbles from the bajada surface have ages from 33 to 141 ka, with a mean of 87 ± 26 ka. A slip rate of 8.1 ± 2.9 mm/a is derived from the mean age, with conservative bounds of 3.8-22.1 mm/a. These results and other published slip rates along the linear WAF segment, from GPS to geological time scales, lack the resolution to fully resolve the question of temporal variations versus consistency of the fault slip rate of the WAF. Yet, given the uncertainties, they are not inconsistent with each other.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.T31A2821G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.T31A2821G"><span id="translatedtitle">Northern San Andreas Fault slip rates on the Santa Cruz Mountain section: <span class="hlt">10</span><span class="hlt">Be</span> dating of an offset alluvial fan complex, Sanborn County Park, Saratoga, CA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guns, K. A.; Prentice, C. S.; DeLong, S. B.; Kiefer, K.; Blisniuk, K.; Burgmann, R.</p> <p>2015-12-01</p> <p>To better assess seismic hazard and fault behavior along the southern peninsula in the San Francisco Bay Area on the Santa Cruz Mountain section of the San Andreas Fault, we combine field observations and high-resolution lidar topography data with <span class="hlt">10</span><span class="hlt">Be</span> exposure dating on offset landforms to estimate geologic fault slip rates. Our mapping at Sanborn County Park near Saratoga reveals a progression of alluvial fans and debris flows offset from their upstream sources by dextral slip on the San Andreas Fault. These upstream sources are 3 drainages, Todd Creek, Service Road Creek and Aubry Creek. Coarse alluvial deposits from each of these creeks contain large Tertiary sandstone boulders of varying size and abundance, derived from the Vaqueros Formation, that allow us to constrain the provenance of offset alluvial deposits to their upstream sources. Initial reconstruction, based on clast-count data on lithology and size from Todd Creek (n=68), Service Road Creek (N=32) and the offset deposits (n=68), suggest ≥140 m of dextral fault movement. Initial <span class="hlt">10</span><span class="hlt">Be</span> cosmogenic dating of sandstone boulders on an offset deposit from Service Road Creek yields a maximum date of 8 ka, a date uncorrected for hillslope residence and fluvial transport of inherited <span class="hlt">10</span><span class="hlt">Be</span> concentrations. These data suggest a minimum slip rate of at least 17 mm/yr on the Santa Cruz Mountain section of the San Andreas Fault in the peninsula. Ongoing analysis will refine this fault slip rate. Our preliminary data underscore the potential of this site to provide geologic slip rate estimates, and therefore answer a question critical to seismic hazard assessment, in a region where steep terrain, mass wasting, vegetation and urban development have generally made slip rate estimates challenging to obtain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21290054','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21290054"><span id="translatedtitle">Energy of the ground and 2{sup +} excited states of {sub {lambda}}{sub {lambda}}{sup <span class="hlt">10</span>}<span class="hlt">Be</span>: A partial ten-body model</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shoeb, Mohammad; Sonika</p> <p>2009-08-15</p> <p>The energies of the ground and excited 2{sup +} states of {sub {lambda}}{sub {lambda}}{sup <span class="hlt">10</span>}<span class="hlt">Be</span> have been calculated variationally in the Monte Carlo framework. The hypernucleus is treated as a partial ten-body problem in the {lambda}{lambda}+{alpha}{alpha} model where nucleonic degrees of freedom of {alpha}'s are taken into consideration ignoring the antisymmetrization between two {alpha}'s. The central two-body {lambda}N and {lambda}{lambda} and the three-body dispersive and two-pion exchange {lambda}NN forces, constrained by the {lambda}p scattering data and the observed ground state energies of {sub {lambda}}{sup 5}He and {sub {lambda}}{sub {lambda}}{sup 6}He, are employed. The product-type trial wave function predicts binding energy for the ground state considerably less than for the event reported by Danysz et al.; however, it is consistent with the value deduced assuming a {gamma} ray of 3.04 MeV must have escaped undetected in the decay of the product {sub {lambda}}{sup 9}Be* {yields} {sub {lambda}}{sup 9}Be+{gamma} of the emulsion event {sub {lambda}}{sub {lambda}}{sup <span class="hlt">10</span>}<span class="hlt">Be</span>{yields} {pi}{sup -}+p+{sub {lambda}}{sup 9}Be* and for the excited 2{sup +} state closer to the value measured in the Demachi-Yanagi event. The hypernucleus {sub {lambda}}{sub {lambda}}{sup <span class="hlt">10</span>}<span class="hlt">Be</span> has an oblate shape in the excited state. These results are consistent with the earlier four-body {alpha} cluster model approach where {alpha}'s are assumed to be structureless entities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMPP11E..03S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMPP11E..03S"><span id="translatedtitle">Eight Million Years of Land-Based Antarctic Ice Sheet Stability Recorded By In Situ <span class="hlt">10</span><span class="hlt">Be</span> from the ANDRILL-1B Core</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shakun, J. D.; Corbett, L. B.; Bierman, P. R.</p> <p>2015-12-01</p> <p>The response of the East Antarctic Ice Sheet (EAIS) to Pliocene warmth provides a critical way to gauge its sensitivity to climate change. Considerable uncertainty surrounds the Pliocene behavior of the EAIS, however. For instance, global sea level estimates for the mid-Pliocene warm period range from <10 m to >30 m, and numerous cosmogenic nuclide and sedimentological studies from the Transantarctic Mountains imply extreme landscape stability over the last several Myr whereas ocean records suggest orbital-scale instability of at least marine-based sectors of the ice sheet. These stabilist versus dynamicist views are difficult to resolve because onshore records are generally biased toward intervals of expanded ice cover and limited to areas with exposed land, while marine sediments typically provide indirect evidence for conditions on land and cannot distinguish between marine versus land-based ice sheet collapse. The AND-1B marine sediment core drilled beneath the Ross Ice Shelf contains a remarkably complete late Cenozoic sequence of glacial diamictons sourced from the adjacent EAIS, intercalated with open-water sediments likely associated with West Antarctic Ice Sheet collapse. We measured concentrations of in situ <span class="hlt">10</span><span class="hlt">Be</span> - produced only when ice cover is reduced and the landscape is exposed - in eight samples of glacially-derived quartz sand from AND-1B spanning parts of the last 8 Myr. Decay-corrected concentrations are low and show a long-term decline from 13,000 atoms/g to 1000 atoms/g over the record. These low values and the monotonic trend suggest that land-based ice sheet sectors have experienced little, if any, exposure during the past 8 Myr; the <span class="hlt">10</span><span class="hlt">Be</span> concentrations we measured are equivalent to only centuries or a few kyr of surface exposure. Perhaps more likely, the small quantities of <span class="hlt">10</span><span class="hlt">Be</span> were produced prior to the establishment of a full EAIS in the mid-Miocene, and reflect deeply-exhumed and thus <span class="hlt">10</span><span class="hlt">Be</span>-poor material that has been radioactively</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26PSL.453...33A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26PSL.453...33A"><span id="translatedtitle">Regolith evolution on the millennial timescale from combined U-Th-Ra isotopes and in situ cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> analysis in a weathering profile (Strengbach catchment, France)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ackerer, J.; Chabaux, F.; Van der Woerd, J.; Viville, D.; Pelt, E.; Kali, E.; Lerouge, C.; Ackerer, P.; di Chiara Roupert, R.; Négrel, P.</p> <p>2016-11-01</p> <p>U-Th-Ra disequilibria, cosmogenic in situ <span class="hlt">10</span><span class="hlt">Be</span> concentrations and major and trace element concentrations have been analyzed in a 2 m-deep weathering profile sampled at the summit of the granitic Strengbach catchment (France). The data have been used to independently estimate both the long-term regolith production and denudation rates and the weathering and erosion rates. Modeling of the 238U-234U-230Th-226Ra disequilibrium variations in the lower part of the profile yields a regolith production rate of 12 ± 4 mm/kyr (30 ± 10 T/km2/yr), while modeling of the high-resolution <span class="hlt">10</span><span class="hlt">Be</span> concentration profile leads to an exposure age of 19.7 ± 2.2 kyr, an inherited concentration of 15,000 ± 1,000 at/g in quartz and a mean denudation rate of 22 ± 10 mm/kyr (37 ± 15 T/km2/yr). The consistency between production and denudation rates suggests that, on a millennial timescale, the regolith mass balance at the summit of the catchment is close to a steady state, even if the watershed may have been impacted by Quaternary climatic changes and by recent anthropogenic perturbations (e.g., 20th century acid rain and recent afforestation efforts). The results also indicate that physical erosion is likely the dominant long-term process of regolith denudation in the catchment. Furthermore, the comparison of the long-term production and denudation rates and of weathering and erosion rates determined from the depth profile analyses with the current weathering and erosion rates estimated at the outlet of the watershed based on monitoring of the water chemistry and sediment fluxes suggests that physical erosion may have varied more than the chemical weathering flux during the last 150 kyr. Although very few other sites with U-series, in situ <span class="hlt">10</span><span class="hlt">Be</span> and stream monitoring data are available for comparison, the current data suggest that (1) the mass balance steady state of regolith might be commonly achieved in soil mantled landscapes, and (2) physical erosion has varied much more than</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JSAES..67...89S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JSAES..67...89S"><span id="translatedtitle">Relief evolution of the Continental Rift of Southeast Brazil revealed by in situ-produced <span class="hlt">10</span><span class="hlt">Be</span> concentrations in river-borne sediments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Salgado, André Augusto Rodrigues; Rezende, Eric de Andrade; Bourlès, Didier; Braucher, Régis; da Silva, Juliana Rodrigues; Garcia, Ricardo Alexandrino</p> <p>2016-04-01</p> <p>This study aims to quantify the denudation dynamics of the Brazilian passive margin along a segment of the Continental Rift of Southeast Brazil. The denudation rates of 30 basins that drain both horsts of the continental rift, including the mountain ranges of the Serra do Mar (seaside horst); and the Serra da Mantiqueira (continental horst); were derived from <span class="hlt">10</span><span class="hlt">Be</span> concentrations measured in sand-sized river sediment. The mean denudation rate ranges from 9.2 m Ma-1 on the plateau of the Serra do Mar to 37.1 m Ma-1 along the oceanic escarpment of the Serra do Mar. The seaward-facing scarps of both mountain ranges exhibit mean denudation rates that are approximately 1.5 times those of the inland-facing scarps. The escarpments of the horst nearer to the ocean (Serra do Mar) exhibit higher denudation rates (mean 30.2 m Ma-1) than the escarpments of the continental horst (Serra da Mantiqueira) (mean 16.5 m Ma-1). The parameters that impact these denudation rates include the catchment relief, the slope gradient, the rock and the climate. The incongruent combination of a mountainous landscape and moderate to low <span class="hlt">10</span><span class="hlt">Be</span>-based denudation rates averaging at ∼20 m Ma-1 suggests a reduction in intraplate tectonic activity beginning in the Middle Quaternary or earlier.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009PhLB..675..170R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009PhLB..675..170R"><span id="translatedtitle">High-precision Penning trap mass measurements of 9,<span class="hlt">10</span><span class="hlt">Be</span> and the one-neutron halo nuclide 11Be</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ringle, R.; Brodeur, M.; Brunner, T.; Ettenauer, S.; Smith, M.; Lapierre, A.; Ryjkov, V. L.; Delheij, P.; Drake, G. W. F.; Lassen, J.; Lunney, D.; Dilling, J.</p> <p>2009-05-01</p> <p>Penning trap mass measurements of 9Be, <span class="hlt">10</span><span class="hlt">Be</span> (t1 / 2 = 1.51 My), and the one-neutron halo nuclide 11Be (t1 / 2 = 13.8 s) have been performed using TITAN at TRIUMF. The resulting 11Be mass excess (ME = 20 177.60 (58) keV) is in agreement with the current Atomic Mass Evaluation (AME03) [G. Audi, et al., Nucl. Phys. A 729 (2003) 337] value, but is over an order of magnitude more precise. The precision of the mass values of 9,<span class="hlt">10</span><span class="hlt">Be</span> have been improved by about a factor of four and reveal a ≈ 2 σ deviation from the AME mass values. Results of new atomic physics calculations are presented for the isotope shift of 11Be relative to 9Be, and it is shown that the new mass values essentially remove atomic mass uncertainties as a contributing factor in determining the relative nuclear charge radius from the isotope shift. The new mass values of 10,11Be also allow for a more precise determination of the single-neutron binding energy of the halo neutron in 11Be.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.T31A2827P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.T31A2827P"><span id="translatedtitle">Preliminary Vertical Slip Rate for the West Tahoe Fault from six new Cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> Exposure Ages of Late Pleistocene Glacial Moraines at Cascade Lake, Lake Tahoe, California</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pierce, I. K. D.; Wesnousky, S. G.; Kent, G. M.; Owen, L. A.</p> <p>2015-12-01</p> <p>The West Tahoe Fault is the primary range bounding fault of the Sierra Nevada at the latitude of Lake Tahoe. It is a N-NW striking, east dipping normal fault that has a pronounced onshore quaternary scarp extending from highway 50 southwest of Meyers, CA to Emerald Bay. At Cascade Lake, the fault cuts and progressively offsets late Pleistocene right lateral moraines. The fault vertically offsets the previously mapped Tahoe moraine ~83 m and the Tioga moraine ~23 m, measured from lidar data. Seventeen samples were collected for <span class="hlt">10</span><span class="hlt">Be</span> cosmogenic age analysis from boulders on both the hanging and footwalls of the fault along the crests of these moraines.We report here the initial analysis of 6 of these boulders and currently await processing of the remainder. The <span class="hlt">10</span><span class="hlt">Be</span> exposure ages of 3 boulders each on the younger Tioga and older Tahoe moraines range from 12.7 +/- 1.6 to 20.7 +/- 3.3 ka and 13.3 +/- 2.1 to 72.5 +/- 8.8 ka, respectively. Using the oldest ages as minima, these preliminary results suggest that the slip rate has averaged ~1 mm/yr since the penultimate glaciation, in accord with estimates of previous workers, and place additional bounds on the age of glaciation in the Lake Tahoe basin. The Last Glacial Maxima and penultimate glaciation near Lake Tahoe thus appear to coincide with the Tioga and Tahoe II glaciations of the Eastern Sierra.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014QSRv...98..135W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014QSRv...98..135W"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> dating of the Narsarsuaq moraine in southernmost Greenland: evidence for a late-Holocene ice advance exceeding the Little Ice Age maximum</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Winsor, K.; Carlson, A. E.; Rood, D. H.</p> <p>2014-08-01</p> <p>In southernmost Greenland near Narsarsuaq, the terminal Narsarsuaq moraine was deposited well outside of a historical Little Ice Age (LIA) moraine adjacent to the modern ice margin. Using <span class="hlt">10</span><span class="hlt">Be</span> surface exposure dating, we determine Narsarsuaq moraine abandonment at 1.51 ± 0.11 ka. A second set of <span class="hlt">10</span><span class="hlt">Be</span> ages from a more ice-proximal position shows that ice has been within or at its historical (i.e., LIA) extent since 1.34 ± 0.15 ka. Notably, Narsarsuaq moraine abandonment was coincident with climate amelioration in southern Greenland. Southern Greenland warming at ˜1.5 ka was also concurrent with the end of the Roman Warm Period as climate along the northern North Atlantic sector of Europe cooled into the Dark Ages. The warming of southern Greenland and retreat of ice from the Narsarsuaq moraine is consistent with studies suggesting possible anti-phase centennial-scale climate variability between northwestern Europe and southern Greenland. Other southernmost Greenland ice-margin records do not preclude a pre-LIA ice-margin maximum, potentially concurrent with a Narsarsuaq advance prior to ˜1.51 ka, but also lack sufficient ice-margin control to confirm such a correlation. We conclude that there is a clear need to further determine whether a late-Holocene pre-LIA maximum was a local phenomenon or a regional southern Greenland ice maximum, and if this advance and retreat reflects a regional fluctuation in climate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.8468P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.8468P"><span id="translatedtitle">The effect of permafrost on soil erosion using meteoric <span class="hlt">10</span><span class="hlt">Be</span>, 137Cs and 239+240Pu in the Eastern Swiss Alps</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pichler, Barbara; Brandovà, Dagmar; Alewell, Christine; Ivy-Ochs, Susan; Kubik, Peter W.; Kneisel, Christof; Meusburger, Katrin; Ketterer, Michael; Egli, Markus</p> <p>2013-04-01</p> <p>Permafrost ecosystems are highly sensitive to climate warming. The expected changes in the thermal and hydrological soil regime might have crucial consequences on soil erosion processes. Therefore, the determination of erosional activities on the long- (since the beginning of soil formation) and mid-term (last 50-60 yr) using cosmogenic and anthropogenic radionuclides can provide important information on past and ongoing processes. Permafrost soils in the Alps and their behaviour with climate change are only rarely studied. The expected new insights will lead to a better understanding of the processes of high mountain soils and are a further step towards improving climate-related modelling of fast warming scenarios and increasing system disequilibria. Our aim is to quantify soil erosion processes in permafrost soils and nearby unfrozen soils in the Alpine (sites at 2700 m asl) and the sub-Alpine (sites 1800 m asl) range of the Swiss Alps (Upper Engadine). We hypothesise that permafrost soils differ distinctly in their long- and mid-term soil erosion rates due to different water retention capacities. Long-term soil erosion was assessed using meteoric <span class="hlt">10</span><span class="hlt">Be</span>. Meteoric <span class="hlt">10</span><span class="hlt">Be</span> in a soil profile was estimated assuming that it is has been deposited as a function of precipitation and adsorbed in the fine earth fraction (</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMEP23A3579L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMEP23A3579L"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> in Quartz Gravel from the Gobi Desert and Evolutionary History of Alluvial Sedimentation in the Ejina Basin, Inner Mongolia, China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lyu, Y.</p> <p>2014-12-01</p> <p>Reconstructing the evolutionary history of the Gobi deserts developed from alluvial sediments in arid regions has great significance in unraveling changes in both tectonic activity and climate. However, such work is limited by a lack of suitable dating material preserved in the Gobi Desert, but cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> has great potential to date the Gobi deserts. In the present study, <span class="hlt">10</span><span class="hlt">Be</span> in quartz gravel from the Gobi deserts of the Ejina Basin in Inner Mongolia of China has been measured to assess exposure ages. Results show that the Gobi Desert in the northern margin of the basin developed 420 ka ago, whereas the Gobi Desert that developed from alluvial plains in the Heihe River drainage basin came about during the last 190 ka. The latter developed gradually northward and eastward to modern terminal lakes of the river. These temporal and spatial variations in the Gobi deserts are a consequence of alluvial processes influenced by Tibetan Plateau uplift and tectonic activities within the Ejina Basin. Possible episodes of Gobi Desert development within the last 420 ka indicate that the advance/retreat of alpine glaciers during glacial/interglacial cycles might have been the dominant factor to influencing the alluvial intensity and water volume in the basin. Intense floods and large water volumes would mainly occur during the short deglacial periods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.T21D1861B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.T21D1861B"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> and U-series dating of late Quaternary landforms along the southern San Jacinto fault: Implications for temporal slip rate variability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Blisniuk, K.; Oskin, M. E.; Fletcher, K.; Sharp, W. D.; Rockwell, T. K.</p> <p>2009-12-01</p> <p>Robust age control on faulted landforms with well-constrained offsets is essential to documenting the heterogeneous behavior of a fault zone over time. However, showing late Quaternary temporal slip rate variation is often challenging due to the difficultly of obtaining reliable ages for Quaternary deposits. Exposure ages from cosmogenic isotopes can be significantly affected by surface processes, and U-series dating of pedogenic carbonate provides only minimum ages because carbonate accumulation occurs after deposition. Fortunately, the controlling factors for the resulting age uncertainties of each method are relatively independent from each other, so a combination of cosmogenic isotope and U-series dating may significantly improve the reliability of landform dating and yield more robust slip rate estimates. We present preliminary results of this dual-dating approach at 4 sites along the southern San Jacinto fault zone in California: 2 sites along the Coyote Creek fault, and 2 sites along the Clark fault. These results show age agreement between the two dating methods. Along the southern Clark fault, a <span class="hlt">10</span><span class="hlt">Be</span> depth profile model age of 34.5 ±6.6 ka and a U-series age of 33.2 ±1.1 ka were obtained for an offset Q2b fan surface, and a Q3b surface yielded a weighted mean <span class="hlt">10</span><span class="hlt">Be</span> surface exposure age of 5.9 ±1.5 ka, similar to an U-series age of 6.3 ±0.4 ka. Along the northern Coyote Creek fault, preliminary data indicate a <span class="hlt">10</span><span class="hlt">Be</span> surface exposure age of 11.3 ±3.4 ka and a U-series age of 11.7 ±1.8 ka for an offset Q3a surface, and a <span class="hlt">10</span><span class="hlt">Be</span> surface exposure age of 6.9 ±1.0 ka and a U-series age of 7.8 ± 0.9 ka for an offset Q3b surface. The remarkable consistency among ages from the two dating methods suggest that: (1) U-series ages of pedogenic carbonate clast rinds closely approach depositional ages of the host alluvium; (2) erosion may be negligible at the sampled sites; and (3) inherited <span class="hlt">10</span><span class="hlt">Be</span> has been accurately quantified (via depth profile) for the late</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1715847R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1715847R"><span id="translatedtitle">In situ produced <span class="hlt">10</span><span class="hlt">Be</span> depth profiles and luminescence data tracing climatic and tectonic control on terrace formation, Danube River, Central Europe, Hungary</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruszkiczay-Rüdiger, Zsófia; Braucher, Régis; Novothny, Ágnes; Csillag, Gábor; Fodor, László; Molnár, Gábor; Madarász, Balázs; Aster Team</p> <p>2015-04-01</p> <p>The terrace sequence of the Hungarian part of the Danube valley preserves a record of varying tectonic uplift rates along the river course and throughout several climate stages. To establish the chronology of formation of these terraces, two different dating methods on alluvial terraces were used: 1) in situ produced cosmogenic <span class="hlt">10</span><span class="hlt">Be</span>, which yield the time of abandonment of the terrace and 2) luminescence dating, which provides burial ages of the sediment. In situ produced cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> samples originated from vertical depth profiles to enable the determination of both the exposure time and the denudation rate at each locality. We used Monte Carlo approach to model the denudation rate-corrected exposure ages. Post-IR IRSL measurements were carried out on K-feldspar samples to obtain the ages of sedimentation. The highest and oldest terrace remnants (tIV-VI) yield a minimum <span class="hlt">10</span><span class="hlt">Be</span> exposure age of 800 ka close to MIS 22, the onset of major continental glaciations of Quaternary age, suggesting climatic signal of the abandonment of the uppermost terrace levels. For the lower terraces it was possible to reveal close correlation with MIS stages using IRSL ages. The new chronology enables the distinction of tIIb (60-110 ka; MIS 4-5d) and tIIIa (130-190 ka; MIS 6) in the study area. Surface denudation rates were well constrained by the cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> depth profiles between 5.9 m/Ma and 10.0 m/Ma for all terraces. Maximum incision rates of the Danube were calculated for middle and late Pleistocene times. These rates were increasing from west to east, toward the more elevated Transdanubian Range from 0.05 mm/a to 0.12 mm/a. Incision rates derived from the age of the low terraces (0.13 mm/a) may suggest a slight acceleration of uplift towards present. Our research was supported by the OTKA PD83610, PD100315, NK60455, K062478, K83150 and F042799, the French-Hungarian Balaton-Tét Project (FR-32/2007; TÉT_11-2-2012-0005), the Bolyai János Scholarship of the Hungarian Academy</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMPP51E..02L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMPP51E..02L"><span id="translatedtitle">Cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> Chronologies of Moraines and Glacially Scoured Bedrock in the Teton Range, with Implications for Paleoclimatic Events and Tectonic Activity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Licciardi, J. M.; Pierce, K. L.; Thackray, G. D.; Finkel, R. C.; Zimmerman, S. R. H.</p> <p>2015-12-01</p> <p>At its Pleistocene maximum, the greater Yellowstone glacial system consisted of an ice cap on the Yellowstone Plateau joined by glaciers from adjacent high mountains, including the Teton Range. In prior research, we obtained 112 exposure ages from moraines and bedrock in this region. These chronologies identified asynchronous outlet glacier culminations around the periphery of the Yellowstone glacier complex, supporting a model of spatial and temporal progressions in buildup and decay of the various ice source regions. Here we build on this previous work and present >30 recently developed <span class="hlt">10</span><span class="hlt">Be</span> exposure ages on glacial features in the Teton Range. Although the Tetons harbored a relatively small portion of the greater Yellowstone ice complex, glaciers in this range left behind some of the region's best-preserved moraine sequences and scoured bedrock. Ongoing investigations are focused on developing moraine chronologies in several drainages on the eastern and western Teton Range fronts, and obtaining exposure ages along scoured bedrock transects in glacial troughs upvalley from the dated moraines to define rates of ice recession. Notably, our dating campaign includes lateral moraines that are offset by the Teton fault, providing a rare opportunity to establish direct constraints on integrated long-term slip rates. All new and previously obtained <span class="hlt">10</span><span class="hlt">Be</span> ages are calculated using recently published calibrations and scaling of <span class="hlt">10</span><span class="hlt">Be</span> production rates. Initial results show that massive lateral moraines in selected drainages are several thousands of years older than adjacent distal end moraines, implying that the laterals were constructed during an earlier phase of the last glaciation and then acted to topographically confine subsequent ice advances. Mean ages of ca. 17-16 ka from terminal moraine loops along with limiting ages from scoured bedrock upvalley of the moraines indicate glacier culminations followed by the onset of rapid ice retreat long after the end of the global</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.1540W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.1540W"><span id="translatedtitle">Consideration of geomorphological uncertainties with terrestrial cosmogenic nuclide dating (TCND): combining Schmidt-hammer and <span class="hlt">10</span><span class="hlt">Be</span> dating, Southern Alps, New Zealand</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Winkler, Stefan</p> <p>2010-05-01</p> <p>As the importance of glaciers as key indicators of global change has increased during recent years, investigating Holocene glaciers chronologies has gained higher attention accordingly. One reason is the need for a better understanding of the climate - glacier relationship. Comparative studies play a major role in this field of research owing to the natural diversity of glacier behaviour. Detailed Holocene glacier chronologies are, furthermore, necessary to verify and eventually adjust glacier models indispensable for many attempts to predict future glacier changes. The Southern Alps of New Zealand are one of the few key study areas on the Southern Hemisphere where, in general, evidence is still sparse compared to its Northern counterpart. Improvement and reassessment of the Late Holocene glacier chronology in this region is, therefore, an important goal of current research. Recently, terrestrial (in situ) cosmogenic nuclide (<span class="hlt">10</span><span class="hlt">Be</span>) surface exposure dating has been increasingly applied to Holocene moraines in New Zealand and elsewhere. In the context of numerical ("absolute") dating techniques, terrestrial cosmogenic nuclide dating (TCND) seems to have been established as an alternative to the previously dominating radiocarbon (14C) dating of organic material (plant remains, organic-rich soil layers etc.) buried beneath or within moraines. Precision and time resolution achieved by the newest laboratory standards and procedures (Schaefer et al. 2009) is truly a milestone and will promote future attempts of TCND in any comparable context. Maybe, TCND has the potential to at least partially replace radiocarbon (14C) dating in its dominating role for the "absolute" dating of Holocene glacial deposits. By contrast, field sampling for TCND often lacks appropriate consideration of geomorphological uncertainties. Whereas much effort is made with the high precision results achieved in the laboratory, the choice of boulders sampled on Holocene moraines is often purely made</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70020234','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70020234"><span id="translatedtitle">Paleopedology plus TL, <span class="hlt">10</span><span class="hlt">Be</span>, and14C dating as tools in stratigraphic and paleoclimatic investigations, Mississippi River Valley, U.S.A.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Markewich, H.W.; Wysocki, D.A.; Pavich, M.J.; Rutledge, E.M.; Millard, H.T.; Rich, F.J.; Maat, P.B.; Rubin, M.; McGeehin, J.P.</p> <p>1998-01-01</p> <p>Thick ( ??? 35 m) loess deposits are present on ridges and high bluffs in the northern-half of the Lower Mississippi Valley (LMV), U.S.A. Detailed descriptions of the loess sections and pedologic, physiochemical, and mineralogic analyses and TL, 14C, and <span class="hlt">10</span><span class="hlt">Be</span> age determinations, allow preliminary paleoclimatic reconstructions for the late Quaternary of central North America. No age data are available for the oldest (Fifth) loess. <span class="hlt">10</span><span class="hlt">Be</span> and TL age data suggest a 250-200 ka age for the Fourth or Crowleys Ridge(?) Loess, and indicate that the Loveland or Third Loess is time equivalent to oxygen isotope stage 6, ??? 190-120 ka. A weakly developed paleosol is present in the basal-half of the Loveland. The Sangamon Geosol is present in the upper 5 m and represents all of oxygen isotope stage 5, ??? 130-60 ka. It formed in a climate as warm as, but drier and (or) with greater variation in precipitation, than the present. The Roxana Silt (second loess) was deposited during oxygen isotope stages 4 and 3, ??? 65-26 ka. The early Wisconsinan interglacial-glacial transition, represented by the Sangamon Geosol and the unnamed paleosol in the basal Roxana Silt, was slow. The paleoclimate during the 35 k yr of Roxana deposition was cool to cold and wet. Age and pedologic data indicate that deposition of the Peoria Loess (the youngest) began around 25 ka when the area's climate changed abruptly from cool or cold and wet to cold and dry, with periods of sustained high winds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMEP52A..05D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMEP52A..05D"><span id="translatedtitle">Placing Absolute Timing on Basin Incision Adjacent to the Colorado Front Range: Results from Meteoric and in Situ <span class="hlt">10</span><span class="hlt">BE</span> Dating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Duehnforth, M.; Anderson, R. S.; Ward, D.</p> <p>2010-12-01</p> <p>A sequence of six levels of gravel-capped surfaces, mapped as Pliocene to Holocene in age, are cut into Cretaceous shale in the northwestern part of the Denver Basin immediately adjacent to the Colorado Front Range (CFR). The existing relative age constraints and terrace correlations suggest that the incision of the Denver Basin occurred at a steady and uniform rate of 0.1 mm yr-1 since the Pliocene. As absolute ages in this landscape are rare, they have the potential to test the reliability of the existing chronology, and to illuminate the detailed history of incision. We explore the timing of basin incision and the variability of geomorphic process rates through time by dating the three highest surfaces at the northwestern edge of the Denver Basin using both in situ and meteoric <span class="hlt">10</span><span class="hlt">Be</span> concentrations. As the tectonic conditions have not changed since the Pliocene, much of the variability of generation and abandonment of alluvial surfaces likely reflects the influence of glacial-interglacial climate variations. We selected Gunbarrel Hill (mapped as pre-Rocky Flats (Pliocene)), Table Mountain (mapped as Rocky Flats (early Pleistocene)), and the Pioneer surface (mapped as Verdos (Pleistocene, ~640 ka)) as sample locations. We took two amalgamated clast samples on the Gunbarrel Hill surface, and dated depth profiles using meteoric and in situ <span class="hlt">10</span><span class="hlt">Be</span> on the Table Mountain and Pioneer surfaces. In addition, we measured the in situ <span class="hlt">10</span><span class="hlt">Be</span> concentrations of 6 boulder samples from the Table Mountain surface. We find that all three surfaces are significantly younger than expected and that in situ and meteoric age measurements largely agree with each other. The samples from the pre-Rocky Flats site (Gunbarrel Hill) show ages of 250 and 310 ka, ignoring post-depositional surface erosion. The ages of the Table Mountain and Pioneer sites fall within the 120 to 150 ka window. These absolute ages overlap with the timing of the penultimate glaciation during marine isotope stage (MIS) 6</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMPP33A2281S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMPP33A2281S"><span id="translatedtitle">Records of Local Glacier Variability in Western Greenland During the Holocene From Lake Sediments, Ice-cap-killed Vegetation, and <span class="hlt">10</span><span class="hlt">Be</span> Dating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schweinsberg, A.; Briner, J. P.; Miller, G. H.; Bennike, O.</p> <p>2015-12-01</p> <p>Local mountain glaciers and ice caps are common and widespread along the periphery of Greenland and provide valuable paleoclimatic records because they respond sensitively to climate change. In contrast to extensive research on Greenland Ice Sheet (GIS) margin changes, the relative timing of mountain glaciation during the Holocene is poorly documented. Here, we use a multi-proxy approach to document the timing of local glacier advance and retreat throughout the past ~10 ka in western Greenland by combining: (1) proglacial lake sediment analysis, (2) 14C-dating of ice-cap-killed in situ plants, and (3) cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> dating. Radiocarbon-dated sediment cores from Sikuiui and Pauiaivik lakes, eastern Nuussuaq, provide minimum-limiting ages for local deglaciation of 9.4 ± 0.06 and 8.8 ± 0.16 ka, respectively, and are in agreement with <span class="hlt">10</span><span class="hlt">Be</span> ages of regional deglaciation that average 10.9 ± 0.7 ka (n=8). Radiocarbon ages (n=54) of in situ plants along retreating cold-based ice cap margins reveal net snowline lowering beginning ~5 ka and are concurrent with the onset of Neoglaciation recorded in both lake systems. Modes of vegetation kill dates highlight distinct ice cap expansion phases at ~3.7, ~3.0, ~1.5 ka, and during the Little Ice Age. The most pronounced snowline lowering event ~4-3 ka is expressed in both lake records by deposition of mineral-rich sediments between ~4.5 and 2.5 ka. Ice cap expansion phases are broadly correlative with elevated minerogenic input in both lakes with some modes in the vegetation ages occurring just prior to increases in mineral-rich sediment input. Published studies of the western GIS margin suggest a major cooling event between ~4.3-3.2 ka, which overlaps with periods of enhanced local glacier activity and ice cap expansion in our dataset. Lastly, the dominant ice cap expansion episode ~3.7 ka in western Greenland is synchronous with a significant snowline lowering event on Baffin Island, suggesting a common climate forcing</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMEP53A0732C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMEP53A0732C"><span id="translatedtitle">Using <span class="hlt">10</span><span class="hlt">Be</span> erosion rates and fluvial channel morphology to constrain fault throw rates in the southwestern Sacramento River Valley, California, USA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cyr, A. J.</p> <p>2013-12-01</p> <p>The Sacramento - San Joaquin River Delta, California, USA, is a critical region for California water resources, agriculture, and threatened or endangered species. This landscape is affected by an extensive set of levees that enclose artificial islands created for agricultural use. In addition to their importance for sustaining agriculture, this levee system also supports extensive transport and power transmission infrastructure and urban/suburban development. These levees are susceptible to damage from even moderate ground shaking by either a large earthquake on one of the high-activity faults in the nearby San Francisco Bay region, or even a moderate earthquake on one of the low-activity faults in the Delta region itself. However, despite this danger the earthquake hazards in this region are poorly constrained due to our lack of understanding of faults in and near the Delta region. As part of an effort to better constrain the seismic hazard associated with known, but poorly constrained, faults in the region, a geomorphic analysis of the Dunnigan Hills, northwest of Woodland, CA, is being combined with cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> catchment-averaged erosion rates. The Dunnigan Hills are a low-relief (maximum elevation 87 m) landscape generated by fault-bend folding above the west-vergent Sweitzer reverse fault that soles into a blind east-vergent reverse fault. These faults have been imaged by seismic reflection data, and local microseismicity indicates that this system is actively propagating to the east. However, the throw rates on the faults in this system remain unconstrained, despite the potential for significant shaking such as that experienced in the nearby April, 1892 earthquake sequence between Winters and Vacaville, Ca, ~25 km to the south, which has been estimated at magnitude 6.0 or greater. Geomorphic and cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> analyses from 12 catchments draining the eastern flank of the Dunnigan Hills will be used to infer vertical rock uplift rates to better constrain</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Geomo.270...40B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Geomo.270...40B"><span id="translatedtitle">Catchment-scale denudation and chemical erosion rates determined from <span class="hlt">10</span><span class="hlt">Be</span> and mass balance geochemistry (Mt. Lofty Ranges of South Australia)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bestland, Erick A.; Liccioli, Caterina; Soloninka, Lesja; Chittleborough, David J.; Fink, David</p> <p>2016-10-01</p> <p>Global biogeochemical cycles have, as a central component, estimates of physical and chemical erosion rates. These erosion rates are becoming better quantified by the development of a global database of cosmogenic radionuclide <span class="hlt">10</span><span class="hlt">Be</span> (CRN) analyses of soil, sediment, and outcrops. Here we report the denudation rates for two small catchments (~ 0.9 km2) in the Mt. Lofty Ranges of South Australia as determined from <span class="hlt">10</span><span class="hlt">Be</span> concentrations from quartz sand from the following landscape elements: 1) dissected plateaux, or summit surfaces (14.10 ± 1.61 t km- 2 y- 1), 2) sandstone outcrops (15.37 ± 1.32 t km- 2 y- 1), 3) zero-order drainages (27.70 ± 1.42 t km- 2 y- 1), and 4) stream sediment which reflect a mix of landscape elements (19.80 ± 1.01 t km- 2 y- 1). Thus, the more slowly eroding plateaux and ridges, when juxtaposed with the more rapidly eroding side-slopes, are leading to increased relief in this landscape. Chemical erosion rates for this landscape are determined by combining cosmogenic denudation rates with the geochemical mass balance of parent rock, soil and saprolite utilizing zirconium immobility and existing mass balance methods. Two different methods were used to correct for chemical weathering and erosion in the saprolite zone that is shielded at depth from CRN production. The corrected values are higher than uncorrected values: total denudation of 33.24 or 29.11 t km- 2 y- 1, and total chemical erosion of 15.64 or 13.68 t km- 2 y- 1. Thus, according to these methods, 32-40% of the denudation is taking place by chemical weathering and erosion in the saprolite below CRN production depth. Compared with other similar areas, the overall denudation and chemical erosion rates are low. In most areas with sub-humid climates and tectonic uplift, physical erosion is much greater than chemical erosion. The low physical erosion rates in these Mt. Lofty Range catchments, in what is a relatively active tectonic setting, are thought to be due to low rainfall intensity</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015E%26PSL.425..154M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26PSL.425..154M"><span id="translatedtitle">Spatial variability of <span class="hlt">10</span><span class="hlt">Be</span>-derived erosion rates across the southern Peninsular Indian escarpment: A key to landscape evolution across passive margins</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mandal, Sanjay Kumar; Lupker, Maarten; Burg, Jean-Pierre; Valla, Pierre G.; Haghipour, Negar; Christl, Marcus</p> <p>2015-09-01</p> <p>The persistence of significant topography in ancient, tectonically inactive orogenic belts remains one of the outstanding questions in geomorphology. In southern Peninsular India, the impressive topographic relief of the Western Ghat Mountains in tectonic quiescence since at least ca. 65 Ma has raised important questions concerning the long-term mechanism of topographic evolution. Quantifying the distribution of erosion in space and time is critical to understanding landscape evolution. Although the long-term erosion rates are reasonably well known, the short-term erosion rates and the relative importance of factors controlling erosion in southern Peninsular India are less well constrained. We present a new suite of catchment-averaged and local erosion rates using in situ produced <span class="hlt">10</span><span class="hlt">Be</span> concentrations in river sediments and exposed bedrock samples in southern Peninsular India. Catchment-averaged erosion rates vary from 9.6 ± 0.8 mMa-1 in the highlands to 114.3 ± 13.8 mMa-1 on the escarpment side. Bedrock erosion rates range from 2.4 ± 0.2 mMa-1 in the ridge-top to 143.4 ± 25.4 mMa-1 in active channel beds of the highlands. Catchment-averaged erosion rates derived from the across-escarpment, westward-draining catchments are significantly higher than those derived from the eastward-draining, over highland catchments. The difference indicates that long-term down-wearing of the highland proceeds at lower rates than in the escarpment zones. Catchment-averaged erosion rates are moderately correlated with mean hillslope angles and local relief whereas they are strongly correlated with catchment-averaged channel steepness index. This suggests that topographic steepness is the major control on the spatial variability of erosion while strong rainfall gradient is of minor importance in this area. <span class="hlt">10</span><span class="hlt">Be</span>-derived average erosion rates in highlands are consistent with previous long-term erosion rate estimated from thermochronometry. These results collectively point to large</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20864204','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20864204"><span id="translatedtitle">Excited states of {sub {lambda}}{sup 9}Be and {sub {lambda}}{sub {lambda}}{sup <span class="hlt">10</span>}<span class="hlt">Be</span> in an {alpha} cluster model</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shoeb, Mohammad</p> <p>2006-12-15</p> <p>The energies of the degenerate spin-flip doublet (3{sup +}/2,5{sup +}/2) of {sub {lambda}}{sup 9}Be and of the 2{sup +} state of {sub {lambda}}{sub {lambda}}{sup <span class="hlt">10</span>}<span class="hlt">Be</span> are analyzed in the {alpha} cluster model using a phenomenological dispersive three-body {lambda}{alpha}{alpha} force that reproduces the ground state energy of {sub {lambda}}{sup 9}Be. Two types of phenomenological {lambda}{alpha} and {alpha}{alpha} potentials and a few s-state {lambda}{lambda} potentials are taken as input. The energies of the excited states of the hypernuclei, treated as three- and four-body systems, calculated using the Variational Monte Carlo method, are in good agreement with the experimental values. Our results demonstrate that the existing data are insensitive to whether one employs a dispersive {lambda}{alpha}{alpha} force along with potentials in the relative angular momentum state l=0 and 2 as in the present work or whether one uses nonlocal {lambda}{alpha} potential as in earlier analyses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016QSRv..145...71D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016QSRv..145...71D"><span id="translatedtitle">Mid-late Pleistocene glacial evolution in the Grove Mountains, East Antarctica, constraints from cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> surface exposure dating of glacial erratic cobbles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dong, Guocheng; Huang, Feixin; Yi, Chaolu; Liu, Xiaohan; Zhou, Weijian; Caffee, Marc W.</p> <p>2016-08-01</p> <p>Glacial histories from the East Antarctic Ice Sheet (EAIS) provide keys to understanding correlations between the EAIS and global climate. They are especially helpful in the assessment of global sea level change, and as a means of quantifying the magnitude of past glacial activity and the rate at which ice responded to climate change. Given the significance of EAIS glacial histories, it is imperative that more glacial chronologic data for this region be obtained, especially for the mid-to-late Pleistocene. We report cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> surface exposure dating results from glacially transported cobbles embedded in blue-ice moraine material at Mount Harding, the Grove Mountains, EAIS. Forty exotic cobbles sampled along two profiles (A and B) on this blue-ice moraine present apparent exposure-ages ranging from 7.2 to 542.2 ka. We explore this scattered dataset by using Principal Component Analysis (PCA) to identify statistically significant trends in the data. We identify a correlation between exposure-age and distance of the cobbles from Mount Harding. In profile A, cobbles further from Mount Harding yield older exposure-ages than those that are relatively close. In profile B, cobbles closer to Mount Harding are found to have relatively older exposure-ages. In term of glacial history we suggest that the direction of ice flow changed during the period from ∼60 to 200 ka, and that multiple glacial fluctuations occurred in the mid-late Pleistocene.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhCS.724a2046S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.724a2046S"><span id="translatedtitle">Microscopic analysis of 10,11Be elastic scattering on protons and 12C and breakup processes of 11Be within the <span class="hlt">10</span><span class="hlt">Be</span>+n cluster model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Spasova, K.; Lukyanov, V. K.; Kadrev, D. N.; Antonov, A. N.; Zemlyanaya, E. V.; Lukyanov, K. V.; Gaidarov, M. K.</p> <p>2016-06-01</p> <p>The elastic scattering cross-sections of 10,11Be on protons and 12C at energy E < 100 MeV/nucleon using microscopically calculated optical potentials (OP) are presented. The real OP is obtained by a folding procedure with effective NN interactions, while the imaginary OP is estimated within the high energy approximation (HEA). The spin-orbit part of the OP is also included. The characteristics of the breakup processes of 11Be on different nuclear targets are also considered. The cross-sections of diffractive breakup and stripping reactions of 11Be on 9Be, 93Nb, 181Ta and 238U at energy E = 63 MeV/nucleon and the longitudinal momentum distributions of <span class="hlt">10</span><span class="hlt">Be</span> fragments produced in the breakup of 11Be on these nuclei are presented. The results are in a good agreement with the available experimental data, in particular the obtained widths of about 50 MeV/c are closed to the empirical ones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013JSAES..48...85G&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013JSAES..48...85G&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">10</span><span class="hlt">Be</span> dating of river terraces of Santo Domingo river, on Southeastern flank of the Mérida Andes, Venezuela: Tectonic and climatic implications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guzmán, Oswaldo; Vassallo, Riccardo; Audemard, Franck; Mugnier, Jean-Louis; Oropeza, Javier; Yepez, Santiago; Carcaillet, Julien; Alvarado, Miguel; Carrillo, Eduardo</p> <p>2013-12-01</p> <p>In this study, we discuss the first cosmogenic <span class="hlt">10</span><span class="hlt">Be</span> dating of river terraces located in the lower reaches of the Santo Domingo river (Southeastern flank of the Mérida Andes, Western Venezuela). The geomorphic observations and dating allowed the restoration of the temporal evolution of incision rate, which was analysed in terms of tectonic, climatic and geomorphic processes. The long-term incision rate in the area has been constantly around 1.1 mm/a over the last 70 ka. Taking into account the geologic and geomorphologic setting, this value can be converted into the Late Pleistocene uplift rate of the Southeastern flank of the Mérida Andes. Our results show that the process of terraces formation in the lower reaches of the Santo Domingo river occurred at a higher frequency (103-104 years) than a glacial/interglacial cycle (104-105 years). According to the global and local climate curve, these terraces were abandoned during warm to cold transitions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NIMPB.370...94R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NIMPB.370...94R"><span id="translatedtitle">The first four years of the AMS-facility DREAMS: Status and developments for more accurate radionuclide data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rugel, Georg; Pavetich, Stefan; Akhmadaliev, Shavkat; Enamorado Baez, Santiago Miguel; Scharf, Andreas; Ziegenrücker, René; Merchel, Silke</p> <p>2016-03-01</p> <p>DREAMS, the DREsden AMS-facility, is performing routine accelerator mass spectrometry of <span class="hlt">10</span><span class="hlt">Be</span>, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, 41Ca, and 129I for a wide range of applications. All DREAMS-data is normalised directly to primary standards or traceable to those via cross-calibration of secondary standards. Recent technical developments such as a low-memory ion source for <span class="hlt">36</span><span class="hlt">Cl</span> and 129I and sophisticated tuning strategies for 129I led to improved-accuracy data. Tests of ion source output have been performed with different metal binders, sample-to-binder mixing ratios, and compaction pressures in order to find optimal parameters. The highest and most stable outputs have been obtained for <span class="hlt">10</span><span class="hlt">Be</span>, <span class="hlt">26</span><span class="hlt">Al</span>, and 41Ca for the following binders and mixing ratios (by weight): BeO:Nb, 1:4; Al2O3:Ag, 1:1; CaF2:Ag, 1:4. Higher beam currents generally result in reduced statistical uncertainty. Cross-contamination and long-term memory seem to be underestimated problems asking for further tests and improvements such as the development of low-level in-house-standards.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70029325','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70029325"><span id="translatedtitle">Climatic and topographic controls on the style and timing of Late Quaternary glaciation throughout Tibet and the Himalaya defined by <span class="hlt">10</span><span class="hlt">Be</span> cosmogenic radionuclide surface exposure dating</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Owen, L.A.; Finkel, R.C.; Barnard, P.L.; Haizhou, Ma; Asahi, K.; Caffee, M.W.; Derbyshire, E.</p> <p>2005-01-01</p> <p>Temporal and spatial changes in glacier cover throughout the Late Quaternary in Tibet and the bordering mountains are poorly defined because of the inaccessibility and vastness of the region, and the lack of numerical dating. To help reconstruct the timing and extent of glaciation throughout Tibet and the bordering mountains, we use geomorphic mapping and <span class="hlt">10</span><span class="hlt">Be</span> cosmogenic radionuclide (CRN) surface dating in study areas in southeastern (Gonga Shan), southern (Karola Pass) and central (Western Nyainqentanggulha Shan and Tanggula Shan) Tibet, and we compare these with recently determined numerical chronologies in other parts of the plateau and its borderlands. Each of the study regions receives its precipitation mainly during the south Asian summer monsoon when it falls as snow at high altitudes. Gonga Shan receives the most precipitation (>2000 mm a-1) while, near the margins of monsoon influence, the Karola Pass receives moderate amounts of precipitation (500-600 mm a-1) and, in the interior of the plateau, little precipitation falls on the western Nyainqentanggulha Shan (???300 mm a -1) and the Tanggula Shan (400-700 mm a-1). The higher precipitation values for the Tanggula Shan are due to strong orographic effects. In each region, at least three sets of moraines and associated landforms are preserved, providing evidence for multiple glaciations. The <span class="hlt">10</span><span class="hlt">Be</span> CRN surface exposure dating shows that the formation of moraines in Gonga Shan occurred during the early-mid Holocene, Neoglacial and Little Ice Age, on the Karola Pass during the Lateglacial, Early Holocene and Neoglacial, in the Nyainqentanggulha Shan date during the early part of the last glacial cycle, global Last Glacial Maximum and Lateglacial, and on the Tanggula Shan during the penultimate glacial cycle and the early part of the last glacial cycle. The oldest moraine succession in each of these regions varies from the early Holocene (Gonga Shan), Lateglacial (Karola Pass), early Last Glacial (western</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013QSRv...62..114P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013QSRv...62..114P"><span id="translatedtitle">The Last Glacial Maximum at 44°S documented by a <span class="hlt">10</span><span class="hlt">Be</span> moraine chronology at Lake Ohau, Southern Alps of New Zealand</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Putnam, Aaron E.; Schaefer, Joerg M.; Denton, George H.; Barrell, David J. A.; Birkel, Sean D.; Andersen, Bjørn G.; Kaplan, Michael R.; Finkel, Robert C.; Schwartz, Roseanne; Doughty, Alice M.</p> <p>2013-02-01</p> <p>Determining whether glaciers registered the classic Last Glacial Maximum (LGM; ˜26,500-˜19,000 yrs ago) coevally between the hemispheres can help to discriminate among hypothesized drivers of ice-age climate. Here, we present a record of glacier behavior from the Southern Alps of New Zealand during the 'local LGM' (LLGM). We used <span class="hlt">10</span><span class="hlt">Be</span> surface-exposure dating methods and detailed glacial geomorphologic mapping to produce a robust chronology of well-preserved terminal moraines deposited during the LLGM near Lake Ohau on central South Island. We then used a glaciological model to estimate a LLGM glacier snowline and atmospheric temperature from the Ohau glacier record. Seventy-three <span class="hlt">10</span><span class="hlt">Be</span> surface-exposure ages place culminations of terminal moraine construction, and hence completions of glacier advances to positions outboard of present-day Lake Ohau, at 138,600 ± 10,600 yrs, 32,520 ± 970 yrs ago, 27,400 ± 1300 yrs ago, 22,510 ± 660 yrs ago, and 18,220 ± 500 yrs ago. Recessional moraines document glacier recession into the Lake Ohau trough by 17,690 ± 350 yrs ago. Exposure of an ice-molded bedrock bench located inboard of the innermost LLGM moraines by 17,380 ± 510 yrs ago indicates that the ice tongue had receded about 40% of its overall length by that time. Comparing our chronology with distances of retreat suggests that the Ohau glacier terminus receded at a mean net rate of about 77 m yr-1 and its surface lowered by 200 m between 17,690 and 17,380 yrs ago. A long-term continuation of ice retreat in the Ohau glacier catchment is implied by moraine records at the head of Irishman Stream valley, a tributary of the Ohau glacier valley. The Irishman Stream cirque glacier advanced to produce a set of Lateglacial moraines at 13,000 ± 500 yrs ago, implying that the cirque glacier was less extensive prior to that advance. We employed a glaciological model, fit to these mapped and dated LLGM moraines, to derive snowline elevations and temperature parameters from the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V13G..03O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V13G..03O"><span id="translatedtitle">How does a single precipitation event erode a landscape? Clues from meteoric 7Be and <span class="hlt">10</span><span class="hlt">Be</span> analysis of suspended sediments and soils</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Occhi, M.; Willenbring, J. K.; Kaste, J. M.; Scholl, M. A.; Shanley, J. B.</p> <p>2012-12-01</p> <p>Stream sediment contains a history recorded in isotopes that cling to suspended particles. In this study we exploit this recorded history in order to understand how a single precipitation event erodes the landscape at two watershed sites (Bisley I and Mameyes) within the Luquillo Critical Zone Observatory, Puerto Rico. We use fallout cosmogenic radionuclides Beryllium-7 (7Be) and Beryllium-10 (<span class="hlt">10</span><span class="hlt">Be</span>) to determine the provenance of suspended sediment at various stages of a hydrograph. Sediments from source areas within the watersheds, such as stable ridge crests and active landslide scars, were also sampled and analyzed. Exploiting the large difference in half-life, the <span class="hlt">10</span><span class="hlt">Be</span>/7Be ratio of suspended sediments coupled with the concentration and nature of organic material present show original depth of mobilized stream sediment in the hillslope. The storm hydrographs of a one-month recurrence interval storm on June 7th, 2011 were sampled at both watersheds. In the small watershed (0.067 km2), storm discharge and total suspended solids (TSS) show short lag times between the initiation of precipitation and the initial rise of the hydrograph and no lag time between peak discharge and peak TSS. The larger site (17.8 km2) had a lag time of approximately 30 minutes between the initiation of precipitation and a rise in discharge and had a 15-minute lag between peak stage (which occurred first) and peak TSS, highlighting the longer travel distances that particles must take to reach the stream sampling point in the larger basin. We compare fallout 7Be nuclide concentration in source sediments and assume a simple, two end-member model to mix these sources in the stream. Soil sediments collected from stable ridge crests ('old') have relatively high average 7Be concentrations of 2.7x106 atoms/g±10% and sediments collected from active landslide scars ('new') have relatively low 7Be concentrations of 4.0x104 atoms/g±15%. Suspended sediments had an average 7Be concentration of 7.2x</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005QSRv...24.1391O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005QSRv...24.1391O"><span id="translatedtitle">Climatic and topographic controls on the style and timing of Late Quaternary glaciation throughout Tibet and the Himalaya defined by <span class="hlt">10</span><span class="hlt">Be</span> cosmogenic radionuclide surface exposure dating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Owen, Lewis A.; Finkel, Robert C.; Barnard, Patrick L.; Haizhou, Ma; Asahi, Katsuhiko; Caffee, Marc W.; Derbyshire, Edward</p> <p>2005-07-01</p> <p>Temporal and spatial changes in glacier cover throughout the Late Quaternary in Tibet and the bordering mountains are poorly defined because of the inaccessibility and vastness of the region, and the lack of numerical dating. To help reconstruct the timing and extent of glaciation throughout Tibet and the bordering mountains, we use geomorphic mapping and <span class="hlt">10</span><span class="hlt">Be</span> cosmogenic radionuclide (CRN) surface dating in study areas in southeastern (Gonga Shan), southern (Karola Pass) and central (Western Nyainqentanggulha Shan and Tanggula Shan) Tibet, and we compare these with recently determined numerical chronologies in other parts of the plateau and its borderlands. Each of the study regions receives its precipitation mainly during the south Asian summer monsoon when it falls as snow at high altitudes. Gonga Shan receives the most precipitation (>2000 mm a -1) while, near the margins of monsoon influence, the Karola Pass receives moderate amounts of precipitation (500-600 mm a -1) and, in the interior of the plateau, little precipitation falls on the western Nyainqentanggulha Shan (˜300 mm a -1) and the Tanggula Shan (400-700 mm a -1). The higher precipitation values for the Tanggula Shan are due to strong orographic effects. In each region, at least three sets of moraines and associated landforms are preserved, providing evidence for multiple glaciations. The <span class="hlt">10</span><span class="hlt">Be</span> CRN surface exposure dating shows that the formation of moraines in Gonga Shan occurred during the early-mid Holocene, Neoglacial and Little Ice Age, on the Karola Pass during the Lateglacial, Early Holocene and Neoglacial, in the Nyainqentanggulha Shan date during the early part of the last glacial cycle, global Last Glacial Maximum and Lateglacial, and on the Tanggula Shan during the penultimate glacial cycle and the early part of the last glacial cycle. The oldest moraine succession in each of these regions varies from the early Holocene (Gonga Shan), Lateglacial (Karola Pass), early Last Glacial (western</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JGRB..115.8401B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JGRB..115.8401B"><span id="translatedtitle">Late Quaternary slip rate gradient defined using high-resolution topography and <span class="hlt">10</span><span class="hlt">Be</span> dating of offset landforms on the southern San Jacinto Fault zone, California</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Blisniuk, Kimberly; Rockwell, Thomas; Owen, Lewis A.; Oskin, Michael; Lippincott, Caitlin; Caffee, Marc W.; Dortch, Jason</p> <p>2010-08-01</p> <p>Recent studies suggest the San Jacinto fault zone may be the dominant structure accommodating PA-NA relative plate motion. However, because the late Quaternary slip history of the southern San Andreas fault system is insufficiently understood, it is difficult to evaluate the partitioning of deformation across the plate boundary and its evolution. Landforms displaced by the Clark fault of the southern San Jacinto fault zone were mapped using high-resolution airborne laser-swath topography and selected offset landforms were dated using cosmogenic <span class="hlt">10</span><span class="hlt">Be</span>. Beheaded channels at Rockhouse Canyon, displaced by 500 ± 70 m and 220 ± 70 m, have been dated to 47 ± 8 ka and 28 ± 9 ka, respectively. Farther south, near the southern Santa Rosa Mountains, an alluvial deposit displaced by 51 ± 9 m has been dated to 35 ± 7 ka. From these sites, the slip rate of the Clark fault is determined to diminish southward from 8.9 ± 2.0 to 1.5 ± 0.4 mm/yr. This implies a slip-rate decrease along the Clark fault from Anza southeastward to its surface termination near the Salton Trough, where slip is transferred to the Coyote Creek fault, and additional deformation is compensated by folding and thrusting in the basin. These data suggest that since ˜30 to 50 ka, the slip rate along the southern San Jacinto fault zone has been lower than, or equivalent to, the rate along the southernmost San Andreas fault. Accordingly, either the slip rate of the San Jacinto fault has substantially decreased since fault initiation, or fault slip began earlier than previously suggested.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFM.H12B0921R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.H12B0921R"><span id="translatedtitle">Long-Term Rates of Erosion and Relief Growth Along the Converging Southern Mexican Margin, Inferred From <span class="hlt">10</span><span class="hlt">Be</span> in Sediment and Regolith</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ramirez-Herrera, T.; Riebe, C. S.; Kirchner, J. W.; Finkel, R. C.</p> <p>2002-12-01</p> <p>Quantifying how erosion and tectonics interrelate is crucial for understanding patterns of sediment yield and for understanding how mountains evolve. Using <span class="hlt">10</span><span class="hlt">Be</span> in alluvial sediment and regolith, we measured long-term rates of erosion and relief generation in granitic mountains along 1800 km of southern Mexico's actively converging Pacific margin. Both the style and rate of plate convergence change significantly along the margin, with much steeper subduction in the south, and convergence increasing from 3 cm/yr to 7 cm/yr along strike from North to South. These differences in convergence should correspond to differences in tectonic activity, and thus in rates of landscape evolution. Our results show that catchment-wide erosion rates along the margin span a five-fold range and are highest (0.6 mm/yr) in the southernmost area, where convergence is fastest. Relief production (estimated here from the difference between ridgetop and catchment-wide erosion rates) also appears to be exceptionally rapid (0.5 mm/yr) in the south. Conversely, in the north, where convergence is slower and subduction is shallower, catchment erosion rates are slower (0.1 mm/yr) and relief is declining, with ridgetops wearing down faster than the catchments around them. Neither differences in lithology nor climate adequately account for the differences in relief growth and erosion rates measured here. We suggest that slower erosion and relief reduction in the north together with faster erosion and relief growth in the south may be signatures of the disparity in the styles and rates of plate convergence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014E%26PSL.405..194K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014E%26PSL.405..194K"><span id="translatedtitle">High-precision <span class="hlt">10</span><span class="hlt">Be</span> chronology of moraines in the Southern Alps indicates synchronous cooling in Antarctica and New Zealand 42,000 years ago</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kelley, Samuel E.; Kaplan, Michael R.; Schaefer, Joerg M.; Andersen, Bjørn G.; Barrell, David J. A.; Putnam, Aaron E.; Denton, George H.; Schwartz, Roseanne; Finkel, Robert C.; Doughty, Alice M.</p> <p>2014-11-01</p> <p>Millennial-scale temperature variations in Antarctica during the period 80,000 to 18,000 years ago are known to anti-correlate broadly with winter-centric cold-warm episodes revealed in Greenland ice cores. However, the extent to which climate fluctuations in the Southern Hemisphere beat in time with Antarctica, rather than with the Northern Hemisphere, has proved a controversial question. In this study we determine the ages of a prominent sequence of glacial moraines in New Zealand and use the results to assess the phasing of millennial climate change. Forty-four <span class="hlt">10</span><span class="hlt">Be</span> cosmogenic surface-exposure ages of boulders deposited by the Pukaki glacier in the Southern Alps document four moraine-building events from Marine Isotope Stage 3 (MIS 3) through to the end of the Last Glacial Maximum (∼18,000 years ago; LGM). The earliest moraine-building event is defined by the ages of nine boulders on a belt of moraine that documents the culmination of a glacier advance 42,000 years ago. At the Pukaki locality this advance was of comparable scale to subsequent advances that, from the remaining exposure ages, occurred between 28,000 and 25,000, at 21,000, and a