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Sample records for accessory minerals zircon

  1. Hunting for eruption ages in accessory minerals

    NASA Astrophysics Data System (ADS)

    Vazquez, J. A.

    2012-12-01

    A primary goal in geochronology is to provide precise and accurate ages for tephras that serve as chronostratigraphic markers for constraining the timing and rates of volcanism, sedimentation, climate change, and catastrophic events in Earth history. Zircon remains the most versatile accessory mineral for dating silicic tephras due to its common preservation in distal pyroclastic deposits, as well as the robustness of its U-Pb and U-series systems even after host materials have been hydrothermally altered or weathered. Countless studies document that zircon may be complexly zoned in age due to inheritance, contamination, recycling of antecrysts, protracted crystallization in long-lived magma reservoirs, or any combination of these. Other accessory minerals such as allanite or chevkinite can retain similar records of protracted crystallization. If the goal is to date the durations of magmatic crystallization, differentiation, and/or magma residence, then these protracted chronologies within and between accessory minerals are a blessing. However, if the goal is to date the timing of eruption with high precision, i.e., absolute ages with millennial-scale uncertainties, then this age zoning is a curse. Observations from ion microprobe 238U-230Th dating of Pleistocene zircon and allanite provide insight into the record of near-eruption crystallization in accessory minerals and serve as a guide for high-precision whole-crystal dating. Although imprecise relative to conventional techniques, ion probe analysis allows high-spatial resolution 238U-230Th dating that can document multi-millennial age distributions at the crystal scale. Analysis of unpolished rims and continuous depth profiling of zircon from small and large volume eruptions (e.g., Coso, Mono Craters, Yellowstone) reveals that the final several micrometers of crystallization often yield ages that are indistinguishable from associated eruption ages from the 40Ar/39Ar or (U-Th)/He methods. Using this approach, we

  2. Integrated single crystal laser ablation U/Pb and (U-Th)/He dating of detrital accessory minerals - Proof-of-concept studies of titanites and zircons from the Fish Canyon tuff

    NASA Astrophysics Data System (ADS)

    Horne, Alexandra M.; van Soest, Matthijs C.; Hodges, Kip V.; Tripathy-Lang, Alka; Hourigan, Jeremy K.

    2016-04-01

    Excimer laser technologies enable a rapid and effective approach to simultaneous U/Pb geochronology and (U-Th)/He thermochronology of a wide range of detrital accessory minerals. Here we describe the 'laser ablation double dating' (LADD) method and demonstrate its viability by applying it to zircon and titanite crystals from the well-characterized Fish Canyon tuff. We found that LADD dates for Fish Canyon zircon (206Pb/238U - 28.63 ± 0.11 Ma; (U-Th)/He - 28.38 ± 0.73 Ma) are statistically indistinguishable from those obtained through established, traditional methods of single-crystal dating. The same is true for Fish Canyon titanite LADD dates: 206Pb/238U - 28.08 ± 0.90 Ma; (U-Th)/He - 27.98 ± 0.86 Ma. As anticipated, given that LADD involves the analysis of smaller amounts of material than traditional methods, it yields dates with higher analytical uncertainty. However, this does not substantially reduce the utility of the results for most applications to detrital datasets. An important characteristic of LADD is that it encourages the chemical characterization of crystals by backscattered electron, cathodoluminescence, and/or Raman mapping prior to dating. In addition, by permitting the rapid and robust dating of crystals regardless of the degree of their abrasion during sedimentary transport, the method theoretically should yield dates that are more broadly representative of those of the entire population of detrital crystals in a natural sample.

  3. Evolution of the continental crust as recorded in accessory minerals

    NASA Astrophysics Data System (ADS)

    Iizuka, Tsuyoshi

    2013-04-01

    Recent developments in precise in situ isotopic analysis by LA-ICPMS and SIMS allow correlating multiple isotopic systems within single grains of accessory minerals such as zircon and monazite. The combined isotope systematics have provided valuable insights into the evolution of the continental crust. Zircon, a common accessory phase in granitoids, can be precisely dated by the U-Pb system. Zircon Lu-Hf isotopic composition is a function of crustal residence time of the magmatic protolith, whereas the O isotopic composition is a sensitive record of reworking of mature sediments such as pelite. An integration of U-Pb, Lu-Hf and O isotopic data for detrital zircons from modern large rivers indicates that: (1) the preserved continental crust dominantly formed between 3.6 and 1.0 Ga, (2) the major mode of crustal development would change during the supercontinent cycle, i.e., the generation of juvenile crust during supercontinent fragmentation versus the stabilization of the generated crust via crustal remelting during supercontinent fragmentation, and (3) reworking of mature sediments increased abruptly at ca. 2.1 Ga. No granitoids are known to have survived since 4.03 Ga. Yet evidence of an even older evolved crust is provided by detrital zircons with ages up to 4.4 Ga from Mt. Narryer and Jack Hills metasedimentary rocks in the Yilgarn Craton, Western Australia. Recently, such Hadean zircons have been found from outside the Yilgarn Craton, indicating that the young Earth had widespread granitoid crust. In addition, another accessory phase, monazite, in the Mt. Narryer and Jack Hills metasedimentary rocks offers an unique opportunity to advance our knowledge of early crustal evolution. Monazite, a light rare earth element phosphate mineral, occurs as an igneous accessory phase particularly in low-Ca granitoids, in contrast to the occurrence of igneous zircon in a wide range of granitoids. U-Pb and Sm-Nd isotope systematic of monazite are analogous to U-Pb and Lu

  4. Identification and significance of accessory minerals from a bituminous coal

    USGS Publications Warehouse

    Finkelman, R.B.; Stanton, R.W.

    1978-01-01

    A scanning electron microscope (SEM) has been used to study the in situ accessory minerals in polished blocks and pellets of petrographically analysed samples of the Waynesburg coal (hvb). Individual grains from the low-temperature ash (LTA) of the same coal were also studied. The visual resolution of the SEM permitted the detection of submicron mineral grains, which could then be analysed by the attached energy-dispersive system. Emphasis was placed on the highly reflective grains in the carbominerite bands. Among the most abundant accessory minerals observed were rutile, zircon, and rare-earth-bearing minerals. Small (1-5 ??m) particles of what may be authigenic iron-rich chromite and a nickel silicate form rims on quartz grains. The SEM also permits the observation of grain morphology and mineral intergrowths. These data are useful in determining authigenicity and diagenic alteration. Substances in density splits of LTA include authigenic, detrital, extraterrestrial magnetite, tourmaline, and evaporite (?) minerals, and a fluorine-bearing amphibole. This analytical approach allows the determination of specific sites for many of the trace elements in coals. In the Waynesburg coal, most of the chromium is in the iron-chromium rims, the fluorine is in the amphibole, and the rare-earth elements are in rare-earth-bearing minerals. The ability to relate trace-element data to specific minerals will aid in predicting the behaviour of elements in coal during combustion, liquefaction, gasification, weathering, and leaching processes. This ability also permits insight into the degree of mobility of these elements in coal and provides clues to sedimentological and diagenetic conditions. ?? 1978.

  5. A software tool to evaluate crystal types and morphological developments of accessory zircon

    NASA Astrophysics Data System (ADS)

    Sturm, Robert

    2014-08-01

    Computer programs for an appropriate visualization of crystal types and morphological developments of accessory zircon are not available hitherto. Usually, typological computations are conducted by using simple calculation tools or spread-sheet programs. In practice, however, high numbers of data sets including information of numerous zircon populations have to be processed and stored. The paper describes the software ZIRCTYP, which is a macro-driven program within the Microsoft Access database management system. It allows the computation of zircon morphologies occurring in specific rock samples and their presentation in typology diagrams. In addition, morphological developments within a given zircon population are presented (1) statistically and (2) graphically as crystal sequences showing initial, intermediate, and final growth stages.

  6. Accessory minerals and subduction zone metasomatism: a geochemical comparison of two mélanges (Washington and California, U.S.A.)

    USGS Publications Warehouse

    Sorensen, Sorena S.; Grossman, Jeffrey N.

    1993-01-01

    Data from the Gee Point and Catalina mélanges suggest that the accessory minerals titanite, rutile, apatite, zircon and REE-rich epidote play a significant role in the enrichment of trace elements in both mafic and ultramafic rocks during subduction-related fluid-rock interaction. Mobilization of incompatible elements, and deposition of such elements in the accessory minerals of mafic and ultramafic rocks may be fairly common in fluid-rich metamorphic environments in subduction zones.

  7. Next steps in using accessory minerals to date the evolution of silicic magmas

    NASA Astrophysics Data System (ADS)

    Vazquez, J. A.

    2011-12-01

    Over the past decade, 238U-230Th-206Pb isotopic dating of accessory minerals using the high spatial resolution and sensitivity of ion microprobe analysis has provided new insights into the longevity and thermochemical evolution of silicic magmas, but has also created new questions about the generation, differentiation, and construction of silicic magma chambers. An important conclusion from in situ dating is that accessory minerals such as zircon and allanite in silicic magmas may be 10's to 100's of thousands of years older than their age of eruption. Whether these relatively "old" crystals are derived from long-lived crystal-rich magma reservoirs or inherited due to remelting of frozen intrusions remains a difficult question to answer because long-lived centers of magmatism are characteristically dynamic and are open systems. Nevertheless, not all rhyolites from loci of repeated silicic magmatism carry a dominant "cargo" of antecrystic zircon (or other accessory minerals). Crystal-poor high-silica rhyolites from Coso volcanic field, eastern California, contain a bimodal population of young zircon that yield 238U-230Th ages concordant with their respective late Pleistocene 40Ar/39Ar eruption ages, and a population of Mesozoic zircon that are obvious xenocrysts derived from wallrocks. Rhyolites erupted from La Primavera caldera, Mexico, contain zircon and chevkinite that yield 238U-230Th ages that are within 10's of k.y. of their corresponding eruption ages between ca. 125-85 ka. Antecrysts from intrusions related to older episodes of rhyolitic magmatism appear absent or exceedingly rare. The relatively short timescales between crystallization and eruption suggest that these rhyolites, unlike otherwise similar rhyolites from other systems, were tapped shortly after highly effective differentiation and/or reheating. It is apparent that zircon ages alone are insufficient for resolving the thermochemical and differentiation histories of silicic magmas, and need to be

  8. Using the potential of accessory minerals: detailed reconstruction of emplacement and crystallization sequence in the Southern Adamello Batholith, N. Italy

    NASA Astrophysics Data System (ADS)

    Broderick, C. A.; Schaltegger, U.; Frick, D.; Guenther, D.; Brack, P.

    2011-12-01

    Recent advances in U-Pb zircon geochronology have revealed the complexities of pluton construction, by multiple injections on 10-100 ka to Ma timescales (Michel et al., 2008, Schaltegger et al., 2009). Using high precision U-Pb dating we are potentially able to describe the duration and evolution of magmatic systems, their crystallization and emplacement within the crust. The potential exists to better understand these processes by detailed study of accessory minerals. The trace element and isotopic characteristics of accessory minerals makes them important information carriers for tracking changes in a magma through time. High precision U-Pb dating, using CA-ID-TIMS and employing the ET2535 tracer solution for <0.1% precision and accuracy on 206Pb/238U zircon and titanite dates, and trace element analyses of zircon and titanite, combined with Hf isotope analysis of zircon are presented for the investigation of a complex magmatic system. This study focuses on the Val Fredda Complex (VFC) in the southern tip of the 43 to 32 Ma Adamello batholith, N. Italy. The VFC displays complex relationships among mafic melts that were injected into solidifying felsic magmas. The mafic units crystallized potential autocrystic zircons over a duration of 100 ka, with the majority of zircons co-crystallizing with titanite. The TIMS-TEA method (Schoene et al., 2010) allows us to analyze trace elements on the same volume of zircon/titanite used for U-Pb dating. Mafic zircon and titanite trace elements (e.g., Eu/Eu* and Sr) suggest that these accessory minerals crystallized prior to plagioclase fractionation. Based on experiments (Ulmer et al., 1983) and the trace element data from this study, we suggest that the mafic zircons and titanites do not represent in situ crystallization and therefore are more likely antecrystic. Data from the VFC felsic units show more complex zircon populations, including xenocrystic, antecrystic and autocrystic zircons. These felsic units have apparent

  9. Accessory and opaque minerals in impact melt rocks of the Boltysh structure, Ukraine

    NASA Astrophysics Data System (ADS)

    Gurov, E. P.; Shekhunova, S. B.; Permyakov, V. V.

    2015-06-01

    Electron microprobe analyses of accessory and opaque minerals from the impact melt rocks of the Boltysh structure, in the central part of the Ukrainian Shield, are presented in this report. Our study establishes a variety of minerals represented by native metals, alloys, oxides, sulfides, phosphates, and silicates, formed during several stages of cooling and solidification of the thick impact melt sheet. Baddeleyite was determined to be the earliest high-temperature mineral to occur in the impact melt rocks. Iron and titanium oxides crystallized earlier or simultaneously with the microliths of orthopyroxene and feldspars. High concentrations of TiO2, Al2O3, and Cr2O3 were identified in some hematite varieties. Cu- and Ni-bearing pyrrhotites occur in impact melt rocks with a glassy matrix. Native metals—copper, platinum, and silver—were likely formed due to the hydrothermal alteration of the upper unit of the impact melt sheet. Zircon is the only accessory mineral found in impact melt rocks that is preserved from the basement granites of the Boltysh structure.

  10. Evaluating 238U/235U in U-bearing accessory minerals

    NASA Astrophysics Data System (ADS)

    Hiess, J.; Condon, D. J.; Noble, S. R.; McLean, N.; Bowring, S. A.; Mattinson, J. M.

    2010-12-01

    U-daughter (U-Pb, Pb-Pb, and U-series) geochronology and cosmochronology utilize the absolute value of the present day 238U/235U ratio to calculate and compare dates. For decades, this value has been assumed to be invariant and equal to 137.88, but recent experiments indicate that there is potential for ‘per mil level’ variation in 238U/235U in natural materials, hypothesized to be the result of redox reactions. These studies have largely focused on materials formed in low-temperature environments (e.g. speleothems, corals) and U ore deposits. At present there are no published high-precision high-accuracy 238U/235U data for U-bearing accessory minerals commonly used for U-Pb geochronology. We present accurate and precise 238U/235U determinations for a suite of common U-bearing accessory minerals (zircon, monazite etc.), from a variety of geological environments and ages. Measurements have been made by thermal ionization mass spectrometry, accurately correcting for mass fractionation using the IRMM 3636 233U-236U double spike. Accessory mineral 238U/235U ratios are generally lower than the ‘consensus’ value of 137.88. Systematic discordance has been observed in 238U/206Pb and 235U/207Pb dates obtained for closed-system minerals, and has been used to reassess the relative decay constants of 238U and 235U (Mattinson, 2000, 2010; Schoene et al., 2006). However, these attempts assumed values (i.e., 137.88 or 137.80) for all present-day 238U/235U ratios. Our new determination of coupled 238U/206Pb, 235U/207Pb and 238U/235U measurements on the same closed system zircons, all traceable to SI units, permit further refinement of λ238U/λ235U estimates. Mattinson J.M. 2000. Revising the "gold standard" - the Uranium decay constants of Jaffey et al., 1971. EOS, AGU Fall meeting Supplement Abstract V61A-02. Mattinson J.M. 2010. Analysis of the relative decay constants of 235U and 238U by multi-step CA-TIMS measurements of closed-system natural zircon samples. Chemical

  11. Progress integrating ID-TIMS U-Pb geochronology with accessory mineral geochemistry: towards better accuracy and higher precision time

    NASA Astrophysics Data System (ADS)

    Schoene, B.; Samperton, K. M.; Crowley, J. L.; Cottle, J. M.

    2012-12-01

    It is increasingly common that hand samples of plutonic and volcanic rocks contain zircon with dates that span between zero and >100 ka. This recognition comes from the increased application of U-series geochronology on young volcanic rocks and the increased precision to better than 0.1% on single zircons by the U-Pb ID-TIMS method. It has thus become more difficult to interpret such complicated datasets in terms of ashbed eruption or magma emplacement, which are critical constraints for geochronologic applications ranging from biotic evolution and the stratigraphic record to magmatic and metamorphic processes in orogenic belts. It is important, therefore, to develop methods that aid in interpreting which minerals, if any, date the targeted process. One promising tactic is to better integrate accessory mineral geochemistry with high-precision ID-TIMS U-Pb geochronology. These dual constraints can 1) identify cogenetic populations of minerals, and 2) record magmatic or metamorphic fluid evolution through time. Goal (1) has been widely sought with in situ geochronology and geochemical analysis but is limited by low-precision dates. Recent work has attempted to bridge this gap by retrieving the typically discarded elution from ion exchange chemistry that precedes ID-TIMS U-Pb geochronology and analyzing it by ICP-MS (U-Pb TIMS-TEA). The result integrates geochemistry and high-precision geochronology from the exact same volume of material. The limitation of this method is the relatively coarse spatial resolution compared to in situ techniques, and thus averages potentially complicated trace element profiles through single minerals or mineral fragments. In continued work, we test the effect of this on zircon by beginning with CL imaging to reveal internal zonation and growth histories. This is followed by in situ LA-ICPMS trace element transects of imaged grains to reveal internal geochemical zonation. The same grains are then removed from grain-mount, fragmented, and

  12. Radiation Effects in Zircon

    SciTech Connect

    Ewing, Rodney C.; Meldrum, Alkiviathes; Wang, L. M.; Weber, William J.; Corrales, Louis R.

    2003-12-11

    The widespread distribution of zircon in the continental crust, its tendency to concentrate trace elements, particularly lanthanides and actinides, its use in age-dating, and its resistance to chemical and physical degradation have made zircon the most important accessory mineral in geologic studies. Because zircon is highly refractory, it also has important industrial applications, including its use as a lining material in high-temperature furnaces. However, during the past decade, zircon has also been proposed for advanced technology applications, such as a durable material for the immobilization of plutonium or, when modified by ion-beam irradiation, as an optic waveguide material. In all of these applications, the change in properties as a function of increasing radiation dose is of critical importance. In this chapter, we summarize the state-of-knowledge on the radiation damage accumulation process in zircon.

  13. Effects of sampling and mineral separation on accuracy of detrital zircon studies

    NASA Astrophysics Data System (ADS)

    SláMa, JiřÃ.­; KošLer, Jan

    2012-05-01

    We investigated some of the sampling and mineral separation biases that affect the accuracy of detrital zircon provenance studies. The study has been carried on a natural catchment in the Scottish Highlands that represents a simple two-component source system and on samples of synthetic sediment prepared for this study to test the effects of heavy mineral separation on the resulting zircon age spectra. The results suggest that zircon fertility of the source rocks and physical properties of zircon represent the most important factors affecting the distribution of zircon age populations in the stream sediments. The sample preparation and selection of zircons for analysis may result in preferential loss of information from small zircon grains. Together with the preference for larger crystals during handpicking, it can result in several-fold difference compared to the real age distribution in the sediment sample. These factors appear to be more important for the reproducibility of zircon age spectra than is the number of zircon grains analyzed per sample.

  14. Dating widespread tephras and their proximal equivalents by SIMS analysis of accessory mineral rims and by argon geochronology (Invited)

    NASA Astrophysics Data System (ADS)

    Vazquez, J. A.; Calvert, A. T.; Matthews, N. E.; Till, C.; Stelten, M. E.; Cooper, K. M.; Marcaida, M.; Lidzbarski, M. I.; Coble, M. A.

    2013-12-01

    Dating the deposition of regionally distributed ash beds whose vent-proximal equivalents are unknown, eroded, or buried by the products of younger eruptions may be challenging because the potassium-rich minerals necessary for high-precision argon geochronology are absent, too small, or altered. Where correlative proximal deposits can be identified, juvenile pyroclasts can be sampled to date their coarse-grained crystals. Zircon is the premier mineral for dating via the U-Pb system, and is commonly present in distal ash beds produced by eruption of silicic magma. However, zircon often yields ages older than eruption due to protracted crystallization in subvolcanic magma chambers, recycling of antecrysts, and/or inheritance. High-spatial resolution sampling of unpolished crystal faces on indium-mounted zircon and other accessory minerals via SIMS (ion microprobe) analysis provides U-Pb or 238U-230Th ages for the final few micrometers of rim crystallization, and represents an alternative technique for avoiding, or at least minimizing, the aforementioned problems. To explore the utility of this technique for dating distal tephras erupted from Quaternary volcanoes in the western United States, we performed U-Pb and U-Th dating of unpolished rims on zircon and allanite in tandem with sanidine 40Ar/39Ar dating for rhyolitic ash beds and proximal pyroclastic deposits or lava associated with a variety of Pleistocene eruptions. Tephra beds generated by late Pleistocene eruptions from Mono Craters, east-central California, are distributed over a significant area of the Great Basin, but their ages have been difficult to resolve due to contamination by sanidine xenocrysts and accidental lithic clasts. Rims on zircon and allanite from a regionally distributed tephra and its correlative rhyolite dome in the Mono Craters both yield U-Th isochron ages of ca. 21 ka, which are indistinguishable from the 40Ar/39Ar age for sanidine from the dome. A distinct tephra that erupted from

  15. Constraints on Hadean geodynamics from mineral inclusions in > 4 Ga zircons

    NASA Astrophysics Data System (ADS)

    Hopkins, Michelle D.; Harrison, T. Mark; Manning, Craig E.

    2010-10-01

    The inclusion mineralogy of 1450 zircons over 4 billion years in age from the Jack Hills, Western Australia, was characterized for composition and phase assemblage. Results confirm that the inclusion population of these largely igneous zircons is dominated by muscovite and quartz (~ 75%). If the inclusions are original to the igneous zircons, this observation alone restricts the host melts to formation at pressure-temperature ( P- T) conditions of ~ 650-800 °C and > 4 kbar. Several lines of evidence support the view that most of the analyzed mineral inclusions are primary, including their lack of association with cracks, magmatic crystal forms, and lack of exchange with fuchsitic (Cr-rich) micas in the host conglomerate. The application of Ti-in-zircon thermometry, and phengite, Ti-in-quartz, and Al-in-hornblende barometry to these inclusion assemblages yields estimates of magmatic P-T conditions from 5 to > 12 kbar and 700 ± 40 °C. These data indicate zircon formation along geotherms of ≤ 60 °C/km and imply conductive near-surface heat flow of < 40 to 85 mW/m 2— a range that is substantially lower than most estimates of global Hadean heat flow. Of the possible environments capable of generating melting under such locally low heat flow early in Earth history, underthrusting, possibly in a manner similar to modern convergent margins, appears most consistent with numerous other geochemical constraints derived from investigation of Hadean zircons.

  16. 238U/235U determinations of some commonly used reference materials and U-bearing accessory minerals (Invited)

    NASA Astrophysics Data System (ADS)

    Condon, D.; Noble, S.; McLean, N.; Bowring, S. A.

    2009-12-01

    We have determined 238U/235U ratios for a suite of commonly used natural (CRM 112a, SRM 950a, HU-1) and synthetic (IRMM 184 and CRM U500) uranium reference materials in addition to several U-bearing accessory phases (zircon and monazite) by thermal ionisation mass-spectrometry (TIMS) using the IRMM 3636 233U-236U double spike to accurately correct for mass fractionation. The 238U/235U values for the natural uranium reference materials differ, by up to 0.1%, from the widely used ‘consensus’ value (137.88) with all having 238U/235U values less than 137.88. Similarly, initial 238U/235U data from zircon and monazite yield 238U/235U values that are lower than the ‘consensus’ value. The data obtained from U-bearing minerals is used to assess how the uncertainty in the 238U/235U ratio contributes to the systematic discordance observed in 238U/206Pb and 235U/207Pb dates (Mattinson, 2000; Schoene et al., 2006) which has traditionally been wholly attributed to error in the U decay constants. The 238U/235U determinations made on the synthetic reference materials yield results that are considerably more precise and accurate than the certified values (0.02% vs. 0.1% for CRM U500). The calibration of isotopic tracers used for U-daughter geochronology that are partially based upon these reference materials, and the resultant age determinations, will benefit from increased accuracy and precision. Mattinson, J.M., 2000. Revising the “gold standard”—the uranium decay constants of Jaffey et al., 1971. Eos Trans. AGU, Spring Meet. Suppl., Abstract V61A-02. Schoene B., Crowley J.L., Condon D.C., Schmitz M.D., Bowring S.A., 2006, Reassessing the uranium decay constants for geochronology using ID-TIMS U-Pb data. Geochimica et Cosmochimica Acta 70: 426-445

  17. Tracking hydrothermal alteration and mineralization in rock-forming and accessory minerals from the Lyon Mountain Granite and related iron oxide apatite (IOA) ores from the Adirondack Mountains, New York State

    NASA Astrophysics Data System (ADS)

    Buchanan, A.; Hanchar, J. M.; Steele-MacInnis, M. J.; Crowley, J. L.; Valley, P. M.; Fisher, C. M.; Fedo, C.; Piccoli, P. M.; Fournelle, J.

    2012-12-01

    The Lyon Mountain granite (LMG) is located in the northeastern Adirondack Mountains in New York State and hosts several low-titanium iron oxide apatite (IOA) ore deposits. The ores are predominately hosted by perthite bearing granite, which has been extensively altered to albite and microcline granite by Na and K metasomatism. This alteration results in several distinct groups of rocks that are dominated by either K or Na addition and a group composed of mixed Na and K addition. The different groups of altered perthite also lie on a trend suggestive of addition of Fe to each, consistent with a secondary mineralization origin. Previous work showed that the host rocks of the IOA ores have zircon with ~1150 Ma cores and 1060-1050 Ma rims and whole grains. This study aims to further constrain the timing of LMG emplacement, subsequent hydrothermal alteration, and Fe mineralization through geochemical analysis of the major, minor, and accessory phases and geochronology of accessory phases. SIMS analyses of zircon from several of the IOA ores reveal at least two periods of growth after LMG magmatism, at 1039 +/- 4.4 Ma and 1016 +/- 7 Ma to 1000 +/- 9 Ma. In situ EMPA and LA-ICPMS trace element analyses of the zircon rims and cores reveal that in two samples the zircon rims are enriched in rare earth elements (REE) compared to their cores, potentially pointing to a hydrothermal origin. Apatite has unusually high REE and Y concentrations (some total REE2O3 > 20 wt. % oxide and up to 8 wt. % oxide Y2O3), as does titanite, which allowed for the in situ analysis of Sm-Nd in apatite and titanite by LA-MC-ICP-MS. Initial Nd isotopic composition of both ore and host rock apatite and host rock titanite are consistent with published Adirondack initial Nd whole rock data, suggesting a local source for REE in these ores. EMPA and LA-ICPMS trace-element analyses of the major rock-forming minerals indicate that the feldspar have undergone Na-metasomatism and are depleted in REEs

  18. Effective LA-ICP-MS dating of common-Pb bearing accessory minerals with new data reduction schemes in Iolite

    NASA Astrophysics Data System (ADS)

    Kamber, Balz S.; Chew, David M.; Petrus, Joseph A.

    2014-05-01

    Compared to non-destructive geochemical analyses, LA-ICP-MS consumes ca. 0.1 μm of material per ablation pulse. It is therefore to be expected that the combined analyses of ca. 200 pulses will encounter geochemical and isotopic complexities in all but the most perfect minerals. Experienced LA-ICP-MS analysts spot down-hole complexities and choose signal integration areas accordingly. In U-Pb geochronology, the task of signal integration choice is complex as the analyst wants to avoid areas of common Pb and Pb-loss and separate true (concordant) age complexity. Petrus and Kamber (2012) developed VizualAge as a tool for reducing and visualising, in real time, U-Pb geochronology data obtained by LA-ICP-MS as an add-on for the freely available U-Pb geochronology data reduction scheme of Paton et al. (2010) in Iolite. The most important feature of VizualAge is its ability to display a live concordia diagram, allowing users to inspect the data of a signal on a concordia diagram as the integration area it is being adjusted, thus providing immediate visual feedback regarding discordance, uncertainty, and common lead for different regions of the signal. It can also be used to construct histograms and probability distributions, standard and Tera-Wasserburg style concordia diagrams, as well as 3D U-Th-Pb and total U-Pb concordia diagrams. More recently, Chew et al. (2014) presented a new data reduction scheme (VizualAge_UcomPbine) with much improved common Pb correction functionality. Common Pb is a problem for many U-bearing accessory minerals and an under-appreciated difficulty is the potential presence of (possibly unevenly distributed) common Pb in calibration standards, introducing systematic inaccuracy into entire datasets. One key feature of the new method is that it can correct for variable amounts of common Pb in any U-Pb accessory mineral standard as long as the standard is concordant in the U/Pb (and Th/Pb) systems after common Pb correction. Common Pb correction

  19. Mineral Chemistry, Thermometry and Geochronological Constraints on the Petrogenesis of Apollo 14 Melt Breccia 14311 Zircons

    NASA Astrophysics Data System (ADS)

    Hopkins, M.; Mojzsis, S. J.

    2012-12-01

    Records of the early thermal history of the Moon have been blurred or erased by later (mare) volcanism and a protracted history of impact bombardments, including the so-called "Late Heavy Bombardment" (LHB) at ca. 3.9 Ga [1]. It is well-documented, however, that lunar impact breccias contain rock and mineral fragments with U-Pb ages that were not wholly re-set by thermal events subsequent to their original formation; many of these pre-date the LHB epoch and yield complex histories perhaps associated with multiple shock events [2-5] of uncertain affinity. It is therefore evident that further detailed geochronological analyses are warranted to uncover a cryptic record of "pre-LHB" bombardments. Lunar zircons are useful in this regard because they are oft-quoted as the most reliable chronometers despite (sometimes significant) thermal metamorphism. A suite of criteria used to elucidate the petrogenetic history of a lunar zircon include: determination whether they are the products of a purely crustal igneous process; crystallized from impact melts; or were so thermally altered that they experienced massive Pb-loss but did not entirely recrystallize via impact heating. Geochemical tools to distinguish between these different scenarios include Ti-in-zircon thermometry [6] and trace element diffusion modeling [7]. We report U-Th-Pb-Ti abundances for 43 lunar zircons extracted from Apollo 14 breccia sample 14311 measured by high-resolution ion microprobe in conventional 2-D spot analysis mode. Results of our analysis show a bimodal distribution of lunar 207Pb/206Pb ages at ca. 3.95 Ga and 4.25 Ga. Thermometry results yield temperatures that range from 800-1200 °C (temperatures >1200 °C are associated with grain fractures and are omitted from our analysis). Younger zircon ages are correlated with slightly higher temperatures compared to the older group, and within the range of modeled impact melt values for the Moon [6]. We interpret the oldest zircon age clusters as

  20. Rare-element granitic pegmatite of Miocene age emplaced in UHP rocks from Visole, Pohorje Mountains (Eastern Alps, Slovenia): accessory minerals, monazite and uraninite chemical dating

    NASA Astrophysics Data System (ADS)

    Uher, Pavel; Janák, Marian; Konečný, Patrik; Vrabec, Mirijam

    2014-04-01

    The granitic pegmatite dike intruded the Cretaceous UHP rocks at Visole, near Slovenska Bistrica, in the Pohorje Mountains (Slovenia). The rock consists mainly of K-feldspar, albite and quartz, subordinate muscovite and biotite, while the accessory minerals include spessartine-almandine, zircon, ferrocolumbite, fluorapatite, monazite- (Ce), uraninite, and magnetite. Compositions of garnet (Sps48-49Alm45-46Grs + And3-4 Prp1.5-2), metamict zircon with 3.5 to 7.8 wt. % HfO2 [atom. 100Hf/(Hf + Zr) = 3.3-7.7] and ferrocolumbite [atom. Mn/(Mn + Fe) = 0.27-0.43, Ta/(Ta + Nb) = 0.03-0.46] indicate a relatively low to medium degree of magmatic fractionation, characteristic of the muscovite - rare-element class or beryl-columbite subtype of the rare-element class pegmatites. Monazite-(Ce) reveals elevated Th and U contents (≤11 wt. % ThO2, ≤5 wt. % UO2). The monazite-garnet geothermometer shows a possible precipitation temperature of ~495 ± 30 °C at P~4 to 5 kbar. Chemical U-Th-Pb dating of the monazite yielded a Miocene age (17.2 ± 1.8 Ma), whereas uraninite gave a younger (~14 Ma) age. These ages are comtemporaneous with the main crystallization and emplacement of the Pohorje pluton and adjacent volcanic rocks (20 to 15 Ma), providing the first documented evidence of Neogene granitic pegmatites in the Eastern Alps. Consequently, the Visole pegmatite belongs to the youngest rare-element granitic pegmatite populations in Europe, together with the Paleogene pegmatite occurrences along the Periadriatic (Insubric) Fault System in the Alps and in the Rhodope Massif, as well as the Late Miocene to Pliocene pegmatites in the Tuscany magmatic province (mainly on the Island of Elba).

  1. Accessories after the facts: Constraining the timing, duration and conditions of high-temperature metamorphic processes

    NASA Astrophysics Data System (ADS)

    Taylor, Richard J. M.; Kirkland, Christopher L.; Clark, Chris

    2016-11-01

    High-temperature metamorphic rocks are the result of numerous chemical and physical processes that occur during a potentially long-lived thermal evolution. These rocks chart the sequence of events during an orogenic episode including heating, cooling, exhumation and melt interaction, all of which may be interpreted through the elemental and isotopic characteristics of accessory minerals such as zircon, monazite and rutile. Developments in imaging and in situ chemical analysis have resulted in an increasing amount of information being extracted from these accessory phases. The refractory nature of these minerals, combined with both their use as geochronometers and tracers of metamorphic mineral reactions, has made them the focus of many studies of granulite-facies terrains. In such studies the primary aim is often to determine the timing and conditions of the peak of metamorphism, and high-temperature metasedimentary rocks may seem ideal for this purpose. For example pelites typically contain an abundance of accessory minerals in a variety of bulk compositions, are melt-bearing, and may have endured extreme conditions that facilitate diffusion and chemical equilibrium. However complexities arise due to the heterogeneous nature of these rocks on all scales, driven by both the composition of the protolith and metamorphic differentiation. In additional to lithological heterogeneity, the closure temperatures for both radiogenic isotopes and chemical thermometers vary between different accessory minerals. This apparent complexity can be useful as it permits a wide range of temperature and time (T-t) information to be recovered from a single rock sample. In this review we cover: 1) characteristic internal textures of accessory minerals in high temperature rocks; 2) the interpretation of zircon and monazite age data in relation to high temperature processes; 3) rare earth element partitioning; 4) trace element thermometry; 5) the incorporation of accessory mineral growth

  2. U-Pb geochronology on zircon and columbite-group minerals of the Cap de Creus pegmatites, NE Spain

    NASA Astrophysics Data System (ADS)

    Van Lichtervelde, Marieke; Grand'Homme, Alexis; de Saint-Blanquat, Michel; Olivier, Philippe; Gerdes, Axel; Paquette, Jean-Louis; Melgarejo, Joan Carles; Druguet, Elena; Alfonso, Pura

    2016-08-01

    The Cap de Creus granitic pegmatites in the eastern Catalan Pyrenees were dated using in situ U-Pb geochronology by laser ablation ICP-MS on zircon and columbite-group minerals (CGM), which are present in the different types of pegmatites from type I (K-feldspar pegmatites, least evolved) to type IV (albite pegmatites, most evolved) and therefore allow dating the different pegmatitic pulses. In a type III pegmatite where zircon and CGM are co-genetically associated in the same sample, both minerals were dated using zircon and tantalite reference materials, respectively, to avoid laser-induced matrix-dependent fractionation. In one sample, xenotime genetically associated with zircon was also dated. Two ages were obtained for type I and three ages for type III pegmatites. Three of these 5 ages range from 296.2 ± 2.5 to 301.9 ± 3.8 Ma and are allocated to the primary magmatic stage of crystallization and therefore to the emplacement event. Two younger ages (290.5 ± 2.5 and 292.9 ± 2.9 Ma) obtained on secondary zircon and xenotime, respectively, are interpreted as late post-solidus hydrothermal remobilization. There is no age difference between type I and type III pegmatites. The mean 299 Ma primary magmatic age allows the main late Carboniferous deformation event to be dated and is also synchronous with other peraluminous and calc-alkaline granites in the Pyrenees. However, the youngest ages around 292 Ma imply that tectonics was still active in Early Permian times in the Cap de Creus area.

  3. Uranium-lead isotope systematics and apparent ages of zircons and other minerals in precambrian granitic rocks, Granite Mountains, Wyoming

    USGS Publications Warehouse

    Ludwig, K. R.; Stuckless, J.S.

    1978-01-01

    Zircon suites from the two main types of granite in the Granite Mountains, Wyoming, yielded concordia-intercept ages of 2,640??20 m.y. for a red, foliated granite (granite of Long Creek Mountain) and 2,595??40 m.y. for the much larger mass of the granite of Lankin Dome. These ages are statistically distinct (40??20 m.y. difference) and are consistent with observed chemical and textural differences. The lower intercepts of the zircon chords of 50??40 and 100+ 75 m.y. for the granite of Long Creek Mountain and granite of Lankin Dome, respectively, are not consistent with reasonable continuous diffusion lead-loss curves but do correspond well with the known (Laramide) time of uplift of the rocks. Epidote, zircon, and apatite from silicified and epidotized zones in the granites all record at least one postcrystallization disturbance in addition to the Laramide event and do not define a unique age of silicification and epidotization. The lower limit of ???2,500 m.y. provided by the least disturbed epidote, however, suggests that these rocks were probably formed by deuteric processes shortly after emplacement of the granite of the Lankin Dome. The earlier of the two disturbances that affected the minerals of the silicified-epidotized rock can be bracketed between 1,350 and 2,240 m.y. ago and is probably the same event that lowered mineral K-Ar and ages in the region. Zircon suites from both types of granite show well-defined linear correlations among U content, common-Pb content, and degree of discordance. One of the zircon suites has an extremely high common-Pb content (up to 180 ppm) and exhibits a component of radiogenic-Pb loss that is apparently unrelated to radiation damage. ?? 1978 Springer-Verlag.

  4. Crystallization of accessory phases in magmas by local saturation adjacent to phenocrysts

    USGS Publications Warehouse

    Bacon, C.R.

    1989-01-01

    Accessory minerals commonly occur attached to or included in the major crystalline phases of felsic and some intermediate igneous rocks. Apatite is particularly common as inclusions, but Fe-Ti oxides, pyrrhotite, zircon, monazite, chevkinite and xenotime are also known from silicic rocks. Accessories may nucleate near the host crystal/ liquid interface as a result of local saturation owing to formation of a differentiated chemical boundary layer in which accessory mineral solubility would be lower than in the surrounding liquid. Differentiation of this boundary layer would be greatest adjacent to ferromagnesian phenocrysts, especially Fe-Ti oxides; it is with oxides that accessories are most commonly associated in rocks. A boundary layer may develop if the crystal grows more rapidly than diffusion can transport incorporated and rejected elements to and from the phenocryst. Diffusion must dominate over convection as a mode of mass transfer near the advancing crystal/liquid interface in order for a boundary layer to exist. Accumulation of essential structural constituent elements of accessory minerals owing to their slow diffusion in evolved silicate melt also may force local saturation, but this is not a process that applies to all cases. Local saturation is an attractive mechanism for enhancing fractionation during crystallization differentiation. If accessory minerals attached to or included in phenocrysts formed because of local saturation, their host phenocrysts must have grown rapidly when accessories nucleated in comparison to lifetimes of magma reservoirs. Some inconsistencies remain in a local saturation origin for accessory phases that cannot be evaluated without additional information. ?? 1989.

  5. Hydrothermal Zircon U-Pb Dating for Early Cretaceous Iron Skarn Mineralization in the Handan-Xingtai District, North China Craton

    NASA Astrophysics Data System (ADS)

    Deng, X., Sr.; Li, J. W., Sr.; Wen, G., Sr.

    2015-12-01

    The Handan-Xingtai district in the North China craton (NCC) is one of the most important concentrations of iron skarn deposits in China. The iron mineralization occurs predominantly along contact zones between early Cretaceous intrusions and Middle Ordovician marine carbonates. We present textural features and LA-ICP-MS U-Pb dating results of hydrothermal zircon to constrain on the time of iron mineralization. Zircon grains from mineralized skarns are subhedral crystals and euhedral tetragonal bipyramids, which are closely intergrown with skarn minerals. They contain abundant inclusions of skarn minerals and daughter mineral-rich (mostly magnetite, halite, and sylvite) fluid inclusions, and have variable Th (518-17477 ppm) and U (109-25610 ppm) contents, with Th/U ratios of 0.01-5.23. These features indicate their hydrothermal origin. The hydrothermal zircon grains from 5 deposits yield concordant U-Pb ages ranging from 133.6 ± 0.9 to 128.5 ± 1.4 Ma (2σ). These ages are consistent with U-Pb ages (134.1 ± 1.2 to 128.5 ± 0.9 Ma; 2σ) of magmatic zircon grains, confirming the reliability of hydrothermal zircon U-Pb ages. Our new geochronological data indicate that iron mineralization and associated magmatism in the Handan-Xingtai district occurred mainly at the ca. 137-133 and 131-128 Ma intervals. These iron skarn deposits represent as the only known giant Mesozoic iron skarn province in a cratonic block on the Earth. Their formation time coincided with lithospheric thinning or destruction of the NCC, strongly suggesting a causal link between the two processes. Our work provides a valuable approach to date iron skarn mineralization by using U-Pb geochronology of hydrothermal zircon and highlights its potential for similar studies. Keywords: Hydrothermal zircon; LA-ICPMS; U-Pb geochronology, iron skarn deposits; North China craton

  6. Source of zircon in world-class heavy mineral placer deposits of the Cenozoic Eucla Basin, southern Australia from LA-ICPMS U-Pb geochronology

    NASA Astrophysics Data System (ADS)

    Reid, Anthony; Keeling, John; Boyd, Doug; Belousova, Elena; Hou, Baohong

    2013-03-01

    The Eucla Basin of southern Australia is a newly recognised zircon-rich mineral sands province with mining operations underway at the world-class Jacinth-Ambrosia deposits. Detrital zircon U-Pb dating via laser ablation inductively coupled plasma mass spectrometry from samples distributed along the length of the Eucla Basin paleoshore system reveals the majority of zircons (c. 55%) are from c. 1300 to 1000 Ma source rocks. Many of the zircons of this age range have metamorphic textures indicating the source province(s) of these zircons underwent high-grade metamorphism during the Mesoproterozoic. A secondary provenance signature occurs at c. 1800-1600 Ma, with significant amounts of c. 1680-1600 Ma zircon. These two key age intervals, c. 1300-1000 Ma and c. 1800-1600 Ma match the major rock-forming intervals of the Albany Fraser Orogen and Musgrave Province, crystalline basement regions that crop out in the western and northern hinterland of the Eucla Basin and which are transected by extensive Early Cenozoic paleodrainage systems. The subordinant volume of Archean zircons in the paleoshoreline deposits are predominantly c. 2660 Ma or older and are most likely derived from the Yilgarn Craton. The primary source regions for the zircons thus lie to the west and north of the main sites of heavy mineral sand accumulation, located in the central and eastern portions of the paleoshoreline complex of the Eucla Basin. This is indicative of the dominant process of westerly longshore drift as the primary control on sediment movement and redistribution along much of the Eucla Basin coastline. Zircons of these ages were also likely derived from recycling sediments of Neoproterozoic and Phanerozoic intracontinental basins, in particular the Officer Basin, which contains dominantly c. 1350-1000 Ma zircons, and was widely incised by the Paleogene drainage network. Monazite U-Pb data from the Jacinth Mine records an abundance of c. 1350-1160 Ma grains, supporting source areas to

  7. Water-compacted Na-bentonite interaction in simulated nuclear fuel disposal conditions: The role of accessory minerals

    SciTech Connect

    Melamed, A.; Pitkaenen, P.

    1994-12-31

    In an earlier laboratory study, ion exchange processes and smectite alteration were investigated through the interaction between compacted Na-bentonite (Volclay MX-80) and simulated granitic groundwater solutions. In the water, a concentration decrease in Ca, Mg and K, and an increase in Na, HCO{sub 3} and SO{sub 4} were recorded. The total amount of Ca available in the water, however, was found insufficient to account for the recorded formation of Ca-smectite, and it is therefore assumed that the accessory Ca-bearing minerals in the bentonite provide the fundamental source of these cations. X-ray powder diffraction analyses and microscope observations of the bentonite samples were re-conducted. Quartz, feldspars, pyrite, calcite and traces of gypsum were revealed as the primary accessories. In reacted samples, goethite and siderite are found as the secondary mineral products in association with corroded pyrite grains, while calcite and gypsum tend to disappear. From these results it is assumed that the oxygen present in the water and bentonite pore space promotes the oxidation of pyrite (dissolved) and the precipitation of goethite. The pore water pH decreases and calcite is partly dissolved. Through the dissolution, the bulk amount of Ca ions in addition to those arising by diffusion from the water is provided. Some of the reaction-released bicarbonate and Fe{sup 2+} re-precipitate in the bentonite as siderite, while the rest (as also SO{sub 4} ions) diffuse into the water. Though the relative oxygen content in the experiment may be considered higher than that of the repository concept for nuclear fuel disposal (interaction in a semi-closed system with high water/bentonite ratio), the near field geochemistry predictions imply limited oxidizing conditions, which will be characterized by the above-described processes in sulphide-bearing bentonite and occur for some time after the sealing of the repository.

  8. Neodymium isotope equilibration during crustal metamorphism revealed by in situ microanalysis of REE-rich accessory minerals

    NASA Astrophysics Data System (ADS)

    Hammerli, J.; Kemp, A. I. S.; Spandler, C.

    2014-04-01

    Radiogenic isotopes are widely used to investigate crustal evolutionary processes, however recent claims of Nd and Sr isotope disequilibrium during anatexis question the reliability of such information. We have conducted an in situ Sm-Nd isotope study of apatite, allanite, titanite, xenotime and monazite in metasedimentary rocks of different metamorphic grade to test Nd isotope equilibrium during metamorphism. Our results show that apatite retains an original, probably detrital, highly variable Nd isotopic signature until at least 500 °C before being isotopically homogenised, irrespective of textural context within the rock. Once equilibrated, apatite retains its Nd isotope signature throughout anatexis. In contrast, allanite and titanite are equilibrated at temperatures as low as 350-400 °C. REE-rich accessory minerals in high-grade rocks (∼600 °C) show very similar initial εNd values at the time of metamorphism. We conclude that under these metamorphic conditions Nd isotope disequilibrium between crustal melts and metasedimentary sources is unlikely. Intra-grain Nd isotope zoning of monazite indicates that partial melting was open system, involving the injection of externally-derived melt into migmatites. This process, likely to be common in anatectic terranes but not always obvious at hand-specimen scale or from bulk rock geochemical data, can produce isotope variation that could potentially be misinterpreted as disequilibrium between the melt and its protolith.

  9. Irraditation-Induced Stabilization of Zircon (ZrSiO4) at High Pressure

    SciTech Connect

    Lang,M.; Zhang, F.; Lian, J.; Trautmann, C.; Neumann, R.; Ewing, R.

    2008-01-01

    Zircon (ZrSiO4), the most important accessory mineral in the Earth's crust, transforms under high pressure to reidite, a scheelite-structured polymorph. Recently, reidite was found in association with meteorite impact structures. Here, we show that the zircon-to-reidite transition, and thus the amount of reidite produced during high-pressure events, strongly depends on the microstructure of the initial zircon. Our results clearly demonstrate that radiation damage, present in natural zircon due to radioactive decay, dramatically modifies the phase stability of crystalline zircon at high pressure. By simulating this radiation damage with ion beams, we show that zircon, pre-irradiated with 1.47-GeV Xe ions, formed only minor amounts of reidite up to 36GPa; whereas, an unirradiated zircon was almost completely transformed to reidite under the same conditions. By means of Raman scattering, X-ray diffraction, and transmission electron microscopy, we confirmed that the stability field of the irradiated zircon is expanded to higher pressures as a result of the interplay between pressure, ion beam-induced amorphization, and the formation of nanoscale damage domains. These results provide insight into the formation-conditions of reidite in nature and illustrate how pressure-induced phase transitions may be affected by defects, in this case those caused by radioactive decay.

  10. Experimental high-grade alteration of zircon using akali- and Ca-bearing solutions: resetting the zircon geochronometer during metasomatism

    NASA Astrophysics Data System (ADS)

    Harlov, D. E.; Dunkley, D.

    2010-12-01

    In nature zircon is one of the principle accessory minerals used for the dating of geologic processes. As a consequence, the stability of zircon in the presence of various possible metamorphic and igneous fluids under a range of P-T conditions and its subsequent alteration with respect to some of these fluids has begun to be explored experimentally as well as speculated upon in a series of natural studies of metasomatised zircons (see review in Geisler et al., 2007 Elements 3, 43-50). Natural alteration of zircon takes place either via dissolution coupled with overgrowth or via fluid-aided coupled dissolution-reprecipitation (Putnis, 2009 Rev Mineral Geochem, vol 70, 87-124). This process results in the zircon being partially or totally replaced by new compositionally re-equilibrated zircon or a new mineral phase or both. In this study, fragments (50 to 200 microns) from a large, inclusion-free, clear, light brown, relatively non-metamict euhedral zircon collected from a nepheline syenite pegmatite (Seiland magmatic province, northern Norway) were experimentally reacted in 20 mg batches with a series of alkali-and Ca-bearing fluids plus a Th + Si source (5 mg ThO2 + ThSiO2 + SiO2) in sealed Pt capsules at 900 °C and 1000 MPa for 6 to 11 days in the piston cylinder press using a CaF2 setup with cylindrical graphite oven. Fluids included 5 mg 2 N NaOH, 5 mg 2 N KOH, 10 mg Na2Si2O5 + 5 mg H2O, 1 mg NaF + 5 mg H2O, and 1 - 5 mg Ca(OH)2 + 5 mg H2O. In each experiment, the fluid reacted with the zircon. This reaction took the form of partial replacement of the zircon with compositionally altered zircon via coupled dissolution-reprecipitation plus varying amounts of overgrowth. The reacted zircon is characterized by a sharp compositional boundary between the altered and original zircon as well as, in some cases, by a micro-porosity and/or inclusions of ZrO2 or ThSiO4. SIMS analysis of the replaced zircon indicates that it is strongly enriched in Th + Si, heavily depleted

  11. Unique accessory Ti-Ba-P mineralization in the Kvalöya ultrapotassic dike, Northern Norway

    NASA Astrophysics Data System (ADS)

    Zozulya, D. R.; Savchenko, E. E.; Kullerud, K.; Ravna, E. K.; Lyalina, L. M.

    2010-12-01

    Unusual ultrapotassic dikes were recently found on the Kvalöya Island in Northern Norway. The dikes crosscutting granites 1.8 Ga in age are 0.1-1.0 m thick and consist of phlogopite phenocrysts in a fine-grained groundmass of K-magnesioarfvedsonite, orthoclase, apatite, and secondary chlorite. According to the composition of the rock-forming minerals (4.5-6.0 wt % K2O and 0.7-3.5 wt % TiO2 in magnesioarfved-sonite, 1.6-3.6 wt % FeO in orthoclase, 9.2-10.7 wt % Al2O3 and 2.1-2.6 wt % TiO2 in phlogopite) and its bulk chemical composition (K/Na = 2.3-2.9, K/Al = 1.0-1.2, (Na + K)/Al = 1.4-1.7, Mg# V = 65-73, (La/Yb) n = 100-140, 3.2-4.0 wt % TiO2, 0.55-1.47 wt % BaO, 2.5-3.0 wt % P2O5, 2650-3000 ppm Zr, 900-1260 ppm REE total, 2300-2500 ppm Sr), the rock corresponds to lamproite of the transitional type. The unique chemical composition of the rock resulted in uncommon Ti-Ba-P accessory mineralization, including baotite Ba4(Ti,Nb)8Si4O28Cl (up to 5 vol %), Sr-apatite (5-7 vol %), and previously unknown Na-Mg-Ba phosphate. Baotite forms anhedral elongated and isometric grains 10-500 μm in size. It is characterized by low Nb (0.03-0.05 f.c.); admixtures of K (0.04-0.12 f.c.) and Sr (0.04-0.07) replacing Ba and Fe (0.01-0.03 f.c.); and Al (0.03-0.04 f.c.) substituting Ti. Euhedral elongated zonal apatite crystals are extremely enriched in SrO (8-12 wt %) and REE2O3 + Y2O3 (6-9 wt %) in the marginal zone. Na-Mg-Ba phosphate occurs as prismatic grains 10-100 μm in size. The atomic ratio of its major cations Na: Mg: Ba: P ˜ 2: 1: 1: 2 corresponds to the conventional formula Na2MgBa(PO4)2; the mineral contains Sr, Mn, Fe, Ca, Si, and Al admixtures.

  12. Roundness of heavy minerals (zircon and apatite) as a provenance tool for unraveling recycling: A case study from the Sefidrud and Sarbaz rivers in N and SE Iran

    NASA Astrophysics Data System (ADS)

    Zoleikhaei, Yousef; Frei, Dirk; Morton, Andrew; Zamanzadeh, S. Mohammad

    2016-08-01

    In order to improve techniques for provenance studies, and especially to address the question of sediment recycling, morphological changes of two minerals with contrasting durability (zircon and apatite) were tracked during both fluvial transport and littoral reworking. The Sefidrud river system in northern Iran, which drains the Alborz volcano-sedimentary range into the Caspian Sea, and the Sarbaz river system in southeastern Iran, which drains the Makran Accretionary Prism into the Oman Sea, were chosen for this study. To determine source rocks of the grains, and thus their nature in terms of sedimentary cycles, zircon geochronology was conducted on both rivers. The zircon data indicate that most of the Sefidrud sediments are first cycle, derived from crystalline rocks, and the Sarbaz sediments are generally recycled from older wedges of the Makran. Results from SEM analysis show significant differences between the roundness of associated zircon and apatite grains. Zircon grains remain unrounded through several cycles, while apatite grains show abrasion from the early stages of their first cycle.

  13. Quaternary dust sources on the Chinese Loess Plateau: a view from single zircon grains, heavy minerals and quartz luminescence

    NASA Astrophysics Data System (ADS)

    Stevens, T.; Carter, A.; Vermeesch, P.; Bird, A.; Rittner, M.; Lu, H.; Andò, S.; Garzanti, E.; Nie, J.; Adamiec, G.; Zeng, L.; Zhang, H.; Xu, Z.

    2013-12-01

    The origin of loess deposits on the Chinese Loess Plateau (CLP), one of the most valuable Cenozoic climate archives on land, is the subject of considerable debate. A large number of sources have been proposed for the vast quantity of dust that forms the up to 400 m thick loess sequences that cover the c. 640,000 km2 the CLP, including deserts, alluvial fans and mountain regions. There is also debate over whether sources shift across the CLP, within loess units, between units and across the Quaternary/Pliocene boundary. Furthermore, the role of river systems in sediment supply to the CLP has not previously been substantively addressed. Geochemical analysis of bulk sediment from loess is limited by mixing of different source influences and so here we apply a variety of techniques to Quaternary sequences on the CLP. We use single-grain based techniques on zircons and heavy mineral analyses in an attempt to discriminate between potential multiple sources and to test the influence of proximal deserts and major rivers on CLP dust. In addition, we utilise information from detailed optically stimulated luminescence dating of quartz from loess to identify rapid shifts in source region on the CLP. Provenance signatures from samples from the eastern Mu Us and the Tengger deserts can be explained by local sources and recycling of the underlying Cretaceous rock. However, the western Mu Us desert as well as Quaternary loess shows different zircon U-Pb age spectra and heavy mineral distributions, indicative of strong influence from northeastern Tibet. Further, samples from the Yellow River are close to identical to these western Mu Us samples and crucially, also to Quaternary samples from the Loess Plateau. This suggests that the Tibetan-derived sediments are unlikely to have been transported from Tibet by wind, but rather may have been delivered by the Yellow River. This provides the first evidence of a possible genetic link between the Yellow River and the CLP. However, there

  14. Mineral inclusions and SHRIMP U-Pb dating of zircons from the Alamas nephrite and granodiorite: Implications for the genesis of a magnesian skarn deposit

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Zhang, Rongqing; Zhang, Zhiyu; Shi, Guanghai; Zhang, Qichao; Abuduwayiti, Maituohuti; Liu, Jianhui

    2015-01-01

    Extending approximately 1300 km and located in the Western Kunlun Mountains, the Hetian nephrite belt is the largest nephrite belt in the world and contains approximately 11 major deposits and more than 20 orebodies including the Alamas deposit. Hetian nephrite deposits can be classified as Mg-skarn deposits with Precambrian dolomitic marble host rock and green, green-white and white nephrite zones are distributed gradually in the zone of a granodiorite pluton. The green nephrite is mainly predominately composed of tremolite with generally minor to trace constituents of diopside, grossularitic garnet, actinolite and other minerals. Also green nephrite has higher content of TFe2O3, than green-white and white nephrites have. We subdivided the zircons from the green nephrites into four types, depending on their internal textures, mineral inclusions, and SHRIMP U-Pb ages. Type I zircons are round instead of idiomorphic in shape and lack obvious zoning. Type II and IV zircons have broad, clear oscillatory zoning and are hypidiomorphic or idiomorphic in shape; they contain inclusions of diopside, tremolite, chlorite and calcite. Most Type III zircons are narrow rims (< 10 μm) surrounding Type II and Type I zircons with highly luminous brightness and no zoning. Both Type I and Type II zircons have individual ages of 411 to 445 Ma and Type IV zircons have younger ages (388 to 406 Ma). Among the concordant ages, 425.7 ± 5.8 Ma and 420.0 ± 9.9 Ma for the QYZr1 and QYZr2 are consistent within error, with the 418.5 ± 2.8 Ma of the Alamas granodiorite formation age and the maximum age of the Alamas nephrite deposit. The partially recrystallization of zircons during skarn formation possibly lead to some younger individual ages (406.5 to 308 Ma). In the Western Kunlun Mountain, both Buya granite and Alamas grandiorite are high Ba-Sr granites and crystallized in Western Kunlun Orogen. The Buya granite formed at about 430 Ma in a post-orogenic tectonic environment. Considering

  15. Cathodoluminescence of radiation-induced zircon

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Y.; Nishido, H.; Kayama, M.; Noumi, Y.

    2013-12-01

    Zircon occurs as a common accessory mineral in igneous, metamorphic and sedimentary rocks, and maintains much information on thermal history, metamorphic process and natural radiation dose accumulated in the mineral. U-Pb zircon dating (e.g., SHRIMP) is an important tool to interpret a history of the minerals at a micrometer-scale, where cathodoluminescence (CL) image has been used for identification of internal zones and domains having different chemical compositions and/or structures with a high spatial resolution. The CL of zircon is derived from various types of emission centers, which are derived from impurities such as rare earth elements (REE) and structural defects. In fact, the CL features of zircon are closely related to metamorphic process and radiation from contained radionuclides as well as geochemical condition of its formation. Most zircon has yellow emission, which seems to be assigned to UO2 centers or radiation-induced defect during metamictization of the lattice by alpha particles from the decay of U and Th. In this study, the radiation effects on zircon CL have been studied for He+ ion-implanted samples annealed at various temperatures to clarify radiation-induced defect centers involved with the yellow CL emission in zircon. Single crystals of zircon from Malawi (MZ), Takidani granodiorite (TZ) and Kurobegawa granite (KZ) were selected for He+ ion implantation experiments. The polished plates of the samples were implanted by He+ ion 4.0 MeV corresponding to energy of alpha particle from 238 U and 232Th. CL spectra in the range from 300 to 800 nm with 1 nm step were measured by a scanning electron microscopy-cathodoluminescence (SEM-CL). CL spectra of untreated and annealed zircon show emission bands at ~370 nm assigned to intrinsic defect centers and at ~480, ~580 and ~760 nm to trivalent Dy impurity centers (Cesbron et al., 1995; Gaft et al, 2005). CL emissions in the yellow-region were observed in untreated zircon. The TZ and KZ indicate

  16. U-Th-Pb systematics of zircon inclusions in rock-forming minerals: A study of armoring against isotopic loss using the Sherman Granite of Colorado-Wyoming, USA

    USGS Publications Warehouse

    Aleinikoff, J.N.

    1983-01-01

    Zircon inclusions were separated from the five major rock-forming minerals of the Sherman Granite of southern Wyoming, in order to evaluate the degree of discordance as a possible function of host minerals. U-Th-Pb isotopic ratios were determined for two size fractions of zircon inclusions from each mineral, plus five size fractions from the bulk rock. Isotopic data from the inclusions have more than double the spread of data on a discordia obtained from the bulk sample, thereby yielding better-resolved concordia intercepts. However, isotopic ratios and morphologic characteristics indicate that the Pb/U systematics are complicated by inherited radiogenic lead. Although the data array cannot unequivocally be explained by the armoring process, the proposed methodology has succeeded in identifying groups of zircon with different isotopic characteristics. As such, this technique can be used to decipher complex geologic/isotopic histories and may be a useful addition to routine zircon geochronology. ?? 1983 Springer-Verlag.

  17. Disturbed Sr and Nd Isotope Systematics in Zircons With Concordant SHRIMP U-Pb Ages

    NASA Astrophysics Data System (ADS)

    Weaver, K. L.; Bennett, V. C.; Depaolo, D. J.; Mundil, R.

    2004-12-01

    Little is known about the Sr- and Nd-isotopic systematics of zircon. With slow diffusion rates and a high resistance to weathering, zircon should preserve accurate age information and initial Sr and Nd isotopic ratios. As a common accessory mineral, it could provide petrogenetic information for rocks that have been altered, weathered, or metamorphosed. We have investigated the Sm-Nd and Rb-Sr systematics of zircons from unmetamorphosed granitic rocks that have yielded concordant U-Pb SHRIMP (Sensitive High Resolution Ion Microprobe) ages and have depleted mantle signatures for Nd and Sr isotopes. Zircon populations from mantle-derived igneous rocks with ages of 0.1, 1.7, and 3.8 Ga were chosen for Sr and Nd isotopic analysis. Low concentrations (Sr, 4 to 8 ppm and Nd, 6 to 12 ppm) and small grain size necessitate the use of multigrain aliquots. Meaningful results can be obtained only if all of the zircons in the rock are a coherent population with homogeneous ages throughout and among grains. Zircon U-Pb ages were characterized using the SHRIMP RG, and trace element concentrations were measured by LA-ICPMS. The populations are homogeneous and the material ablated by the ion beam ( ˜~20 μ m spot size) shows little evidence of lead loss. Results on zircons of 100 Ma and 1700 Ma indicate that both the Rb-Sr and Sm-Nd systems have been severely disturbed. For the 1700 Ma granitic rocks from the Yavapai sequence of Arizona, zircon Sm-Nd apparent ages are ca. 1000 Ma! Leaching was used to remove contributions from adhering or included minerals, but leached residues that presumably most closely approximate the composition of the pure zircon (e.g. have high Sm/Nd) are no less disturbed than unleached samples. Despite the U-Pb SHRIMP ages indicating a closed system, the zircons have failed to preserve a reasonable age or initial isotopic composition for Sr and Nd, indicating that parts of the crystal might be severely affected by radiation damage resulting in disturbed

  18. Elemental Analysis of Zircon by High Mass Resolution USGS-Stanford SHRIMP-RG: Measuring and Evaluating Ti-in-zircon Temperatures and Compositional Characteristics

    NASA Astrophysics Data System (ADS)

    Wooden, J. L.; Mazdab, F. K.; Claiborne, L. L.; Miller, C. F.; Barth, A. P.

    2006-12-01

    High mass resolution of SHRIMP-RG permits measurement of a large set of trace elements for zircon, including 48Ti, Sc, and Nb (requiring better than 9,000 MR) and Be, B, F, P, 49Ti, V, Y, all the REE, Hf, Th, and U (Mazdab and Wooden 2006). A 15-20 micron spot allows analysis of numerous discrete CL zones from single zircons with minimal contributions from unknown material below the exposed surface. Data from suites of zircons from more than 20 individual granitoid samples suggest several general observations: (1) Temperatures calculated by Ti-in-zircon (Watson et al 2006) are entirely compatible with petrologic constraints; uncertainty in a(TiO2) introduces uncertainty in calculated T, but for reasonable values between 0.5 and 0.8 T's consistently fall between 650 and 900 C, mostly in the lower half of the range; (2) T can vary by 150-200 C within suites of zircons from individual samples and even in single zircons, where zonation may be normal (high to low, core to rim), reverse (low to high) or fluctuating; (3) Hf concentrations increase with decreasing T because of Zr/Hf fractionation between zircon and melt (Claiborne et al in press); (4) Many elements and element ratios show a co-variation with T and Hf concentration e.g., Th/U and MREE/HREE decrease with increasing Hf and decreasing T. Hf concentrations can continue to increase after a minimum T is reached, indicating continuing zircon growth from remaining (near eutectic?) melt. Yb/Gd (steepness of the HREE pattern) is an excellent monitor of fractionation, particularly at lower T (below 750 C) where the ratio increases rapidly. This trend may result from co-fractionation of accessory minerals and/or be driven by the thermodynamics of crystal growth, and/or may involve other factors and processes as yet poorly understood. Magmatic zircons commonly have a negative Eu anomaly of about 0.5 or lower which may change little or become more pronounced with falling T; anomalies probably reflect feldspar

  19. Cretaceous tectonism, mineralization & hydrocarbon trap formation in the northern Canadian Cordillera: results of zircon (U-Th)/He thermochronology

    NASA Astrophysics Data System (ADS)

    Schneider, David; Powell, Jeremy; Ryan, Jim

    2013-04-01

    The northern Intermontane terranes of the Canadian Cordillera are dissected by a series of diachronous dextral strike-slip faults, including the Cretaceous Teslin fault possessing moderate displacement (~100 km) and the major Tertiary Tintina fault with >400 km displacement. The Teslin can be traced down to 7-8 seconds (~20 km) in seismic profiles and likely originated as a SW-directed thrust fault during the Jurassic which has been reactivated as a strike-slip fault in the Cretaceous. Jurassic cooling and exhumation of the middle crust now exposed across the central Yukon Cordillera has been slowly coming to light. We suggest unroofing is likely more widespread and long-lived then previously documented. Thirty Paleozoic and Mesozoic granitoids from the northern termination of the Teslin fault were selected for (U-Th)/He zircon thermochronology and only samples that exhibited typical igneous zoning and lack metamorphic overgrowths were analyzed. Analyses yield robust and reliable ages for each sample, which can be divided into three fault-parallel corridors: 215-130 Ma, 115-90 Ma, and 70-55 Ma. No clear pattern emerges when comparing age versus elevation, grain size, or mineral chemistry. The Klondike Plateau and rocks directly west of the Tintina fault record Jurassic cooling. The youngest domainal ages are proximal to voluminous Early to Mid-Cretaceous plutons and fault splays of the Teslin system, where structures with overall small displacement are associated with gold and copper-gold deposits. The remaining structural-age corridor can be resolved into a SW-directed extrusion wedge geometry, exhuming a large portion of the Yukon-Tanana terrane during Albian-Cenomanian tectonism. In the Cordilleran foreland front range of the Northwest Territories, 500 km to the northeast, detrital ZHe ages from ten Neoproterozoic units record contemporaneous cooling during the Late Cretaceous. Moreover, a subset of these samples serves to resolve the timing of movement on the

  20. Zircon and monazite response to prograde metamorphism in the Reynolds Range, central Australia

    NASA Astrophysics Data System (ADS)

    Rubatto, Daniela; Williams, Ian S.; Buick, Ian S.

    2001-01-01

    We report an extensive field-based study of zircon and monazite in the metamorphic sequence of the Reynolds Range (central Australia), where greenschist- to granulite-facies metamorphism is recorded over a continuous crustal section. Detailed cathodoluminescence and back-scattered electron imaging, supported by SHRIMP U-Pb dating, has revealed the different behaviours of zircon and monazite during metamorphism. Monazite first recorded regional metamorphic ages (1576 ± 5 Ma), at amphibolite-facies grade, at ˜600 °C. Abundant monazite yielding similar ages (1557 ± 2 to 1585 ± 3 Ma) is found at granulite-facies conditions in both partial melt segregations and restites. New zircon growth occurred between 1562 ± 4 and 1587 ± 4 Ma, but, in contrast to monazite, is only recorded in granulite-facies rocks where melt was present (≥700 °C). New zircon appears to form at the expense of pre-existing detrital and inherited cores, which are partly resorbed. The amount of metamorphic growth in both accessory minerals increases with temperature and metamorphic grade. However, new zircon growth is influenced by rock composition and driven by partial melting, factors that appear to have little effect on the formation of metamorphic monazite. The growth of these accessory phases in response to metamorphism extends over the 30 Ma period of melt crystallisation (1557-1587 Ma) in a stable high geothermal regime. Rare earth element patterns of zircon overgrowths in leucosome and restite indicate that, during the protracted metamorphism, melt-restite equilibrium was reached. Even in the extreme conditions of long-lasting high temperature (750-800 °C) metamorphism, Pb inheritance is widely preserved in the detrital zircon cores. A trace of inheritance is found in monazite, indicating that the closure temperature of the U-Pb system in relatively large monazite crystals can exceed 750-800 °C.

  1. Insights from heavy minerals and zircon U-Pb ages into the middle Miocene-Pliocene provenance evolution of the Yinggehai Basin, northwestern South China Sea

    NASA Astrophysics Data System (ADS)

    Jiang, Tao; Cao, Licheng; Xie, Xinong; Wang, Zhenfeng; Li, Xushen; Zhang, Yingzhao; Zhang, Daojun; Sun, Hui

    2015-08-01

    The well-preserved Cenozoic sedimentary record in the Yinggehai Basin, South China Sea, is suitable to explore the tectonic and climatic evolution of SE Asia. Red River, a large-scale fluvial system in this region, was previously regarded as the major sediment source for the basin. Here we combine heavy mineral analysis and detrital zircon U-Pb dating to shed new light on the middle Miocene-Pliocene provenance evolution at a basin scale. The results clearly reveal potential source areas additional to the Red River. Sediments have been delivered to the proximal areas from Hainan Island, as indicated by the high zircon content and the Yanshanian U-Pb ages in the southern segment of the Yingdong Slope. A provenance from Central Vietnam is explicitly discerned in the upper Miocene of the Central Depression, where sediments are characterized by few metamorphic heavy minerals and the U-Pb age pattern peaking at around 250 Ma and 440 Ma. Coeval large-scale relative sea-level fall and rapid exhumation along the Vietnamese margin together may have facilitated this long-distance sediment transport. Provenance of sediments from the Red River seems to change over time. Song Lo River, on the north side of the main stream, probably flowed from the NE and carried Neoproterozoic-early Paleozoic zircons to the Yinggehai Basin during the middle Miocene. Since the late Miocene, rocks along the Red River Fault Zone have become the dominant source. Subsequently, widespread metamorphic minerals in the Central Depression of the Yinggehai Basin, combined with the strong river incision and high offshore sedimentation rates, indicate an increased sediment supply from the Red River in the Pliocene.

  2. Textures and geochemistry of zircons in ODP holes 735B and 1105A, Atlantis Bank, SWIR

    NASA Astrophysics Data System (ADS)

    John, B. E.; Cheadle, M. J.; Rioux, M. E.; Wooden, J. L.; Baines, G.

    2012-12-01

    Zircon is a common accessory mineral in ocean crust, and an important chronometer for studying the timing and duration of crustal accretion. Here, we present a comprehensive textural/geochemical study of zircon in 25 samples from the length of ODP Hole 735B (1508m) and adjacent Hole 1105A (158m) at Atlantis Bank, South West Indian Ridge (SWIR). Two zircon-bearing rock suites include i) a dioritic suite comprising amphibole granodiorite, quartz diorite and diorite dikes/veins, and ii) a suite of oxide gabbro segregations/veins. Combined TIMS U/Pb dating (Rioux et al, this meeting) and SIMS REE and other trace element (TE) chemical analyses of these zircons provide constraints on the growth and thermal history of ocean crust, and melt evolution. Zircons from both drill holes vary in morphology, but are typically pristine, colorless euhedral to anhedral grains from ~50-1000 μm in the long dimension. Over 90% show weak sector zoning, and ~50% show oscillatory zoning in CL. Additional textures include: 1. resorbed rims in two dioritic veins; 2. high U rims in two additional dioritic veins; 3. internal resorption/recrystallization boundaries in one diorite dike and one oxide gabbro; 4. a sub-population of high U grains hosting mottled/spongy interiors, possibly indicative of disequilibrium/reaction, in one diorite dike; and 5. mineral/melt inclusions in zircons in most of the dioritic veins, and in ~50% of oxide gabbros. SIMS analyses of 390 zircons (>750 spot analyses) confirm that the zircons have TE concentrations (including U/Yb vs Hf) typical of those from ocean crust. U ranges from <10 to >800 ppm in zircons from the dioritic veins (mean 123 ppm), and 5 to >500 ppm in zircons from the oxide gabbros (mean 59 ppm). All analyzed zircons have steep positive REE slopes with distinct positive Ce and negative Eu anomalies (Ce/Ce* and Eu/Eu*), similar to other oceanic zircons. Zircons from dioritic veins are REE-enriched (ΣREE = 216-15670; mean 3000 ppm) and have

  3. Rhyolite magma evolution recorded in isotope and trace element composition of zircon from Halle Volcanic Complex

    NASA Astrophysics Data System (ADS)

    Słodczyk, E.; Pietranik, A.; Breitkreuz, C.; Fanning, C. M.; Anczkiewicz, R.; Ehling, B.-C.

    2016-04-01

    Voluminous felsic volcanic magmas were formed in Central Europe at the Carboniferous/Permian boundary in numerous pull-apart basins; one of which is the Saale Basin, which holds the Halle Volcanic Complex (HVC), the focus of this study. The rhyolites in the HVC formed laccoliths and scarce lavas, and occur in two different textural types: fine and coarse porphyritic. Zircon isotope and trace element composition was analysed in four units, two per each textural type. Zircon from the different units shows similar ranges in εHf (- 4.1 to - 8.1) and δ18O values (6.51-8.26), indicating similar sources and evolution processes for texturally diverse rhyolites from the HVC. Scarce inherited zircon ranges from ~ 315 Ma to ~ 2100 Ma with the major groupings around 315-550 Ma. These ages are typical for Devonian arc magmatic activity (350-400 Ma) and Cadomian igneous rocks (500-600 Ma), which occur in the basement presently underlying the HVC. Therefore, the source of the rhyolites was multicomponent and probably represented by a basement composed of various crystalline rocks. Trace elements in zircon show similar distributions in all analysed samples, which is broadly consistent with zircon cores crystallizing in a less evolved magma undergoing limited fractional crystallization, whilst the zircon rims crystallized from a magma undergoing extensive fractional crystallization of major and accessory minerals. Interestingly, comparison of the zircon composition in HVC rhyolites and other rhyolites worldwide shows that the observed trends are similar in such rhyolites despite the values being different. This may suggest that most of the zircon in rhyolites crystallizes at a similar stage in the rhyolite magma evolution, from magmas undergoing extensive crystallization of major phases and apatite. The implication is that most of the zircon represents late stage crystallization, but also that antecrystic component may be present and preserve information on the development of

  4. HRTEM study of zircon from Eliseev anorthosite complex, Antarctica

    SciTech Connect

    Wirth, R.; Kaempf, H.; Hoehndorf, A.

    1996-12-31

    Zircon-bearing rocks of this study are metamorphic oxide-apatite gabbronorites (OAGN) from the Eliseev Anorthosite Complex, Wohlthat-Massif, East Antarctica. These unusual rocks are strongly enriched in accessory minerals apatite: <10 vol.%; zircon: < 1 vol.. Three steps in the evolution of these rocks are distinguished: a magnetic formation, followed by a granulite facies metamorphism and finally a tectonomagmatic overprint. The zircon crystals of this study are brown colored, up to 12 mm in length and up to 3 mm wide. Petrological investigations show that zircon has formed during the granulite facies event. Optical microscopy and cathodoluminiscence microscopy reveal a rhythmic zoning and many microcracks. The concentrations of uranium and thorium are low (U: 34-89 ppm and Th: 3-9 ppm). The radiation damage by radioactive decay of U and Th is expected to be minor due to the low uranium and thorium content. The investigations were carried out in a Philips CM200 transmission electron microscope. Analytical electron microscopy was performed by energy dispersive analysis (EDAX).

  5. Zircon geochronology and Hf isotopic composition of Mesozoic magmatic rocks from Chizhou, the Lower Yangtze Region: Constraints on their relationship with Cu-Au mineralization

    NASA Astrophysics Data System (ADS)

    Yang, Wei; Zhang, Hong-Fu

    2012-10-01

    Zircon U-Pb ages and Hf isotopic compositions of Mesozoic magmatic rocks from the Chizhou Area are systematically investigated to reveal the tectonic setting of magmatism and their relationship with Cu-Au mineralization in the Lower Yangtze River Belt, southeastern China. The samples cover nearly all types of magmatic rocks in a 30 × 50 km2 region, including 6 granite porphyries, 6 dacites and 4 granites. The zircon U-Pb geochronology yields a range of 151-124 Ma, with granite porphyries ranging from 151 to 146 Ma, dacites from 132 to 127 Ma and granites from 127 to 124 Ma, indicating two magmatic episodes of the late Jurassic and the early Cretaceous. The earlier episode mainly formed small granite porphyries (generally < 5 km) and is always associated with porphyry Cu-Au deposits. The later episode began with dacites and was then dominated by large granite intrusions (generally > 10 km), which are barren in mineralization. The ore-barren dacites and the granites (131-124 Ma) are poor in inherited zircons. Zircons in these rocks yield a very large ɛHf(t) variation of - 20.8-0.4, suggesting a mixing between mantle-derived and crustal-derived magmas. By contrast, the ore-bearing porphyries (151-146 Ma) are rich in inherited zircons. The magmatic zircons have ɛHf(t) values of - 8.8-0.9, and the inherited ones yield U-Pb ages of 1156-811 Ma with ɛHf(t) values of 2.5-11.5. The existence of quantitative inherited zircons indicates that the crustal rocks of 1156-811 Ma significantly contribute to the formation of the ore-bearing porphyries, either being source or contamination. Since these inherited zircons are igneous as indicated by their oscillatory zonings, they may derive from components of the Grenvillian oceanic crust (ca. 1100-1000 Ma), i.e. the Neoproterozoic magmatic rocks related to arc (970-890 Ma) and Nanhua rift (ca. 825 Ma). Recent studies reveal that the ore-baring porphyries of the Lower Yangtze River Belt have slab melt features and conclude that

  6. Gahnite, chrysoberyl and beryl co-occurrence as accessory minerals in a highly evolved peraluminous pluton: The Belvís de Monroy leucogranite (Cáceres, Spain)

    NASA Astrophysics Data System (ADS)

    Merino, E.; Villaseca, C.; Orejana, D.; Jeffries, T.

    2013-10-01

    Gahnite (ZnAl2O4), chrysoberyl (BeAl2O4) and beryl (Be3Al2Si6O18) have been found as accessory minerals in the external, highly fractionated, leucogranitic unit within the Hercynian reversely zoned Belvís de Monroy pluton (westernmost part of the Montes de Toledo batholith, Cáceres, Spain). The highly felsic (SiO2 > 72 wt.%) and peraluminous (ACNK > 1.2) character of this leucogranite, together with the high content of some incompatible elements (F, Li, B, and P), seems to be a primary consequence of fractional crystallization in a magmatic closed-system. The high Be contents and Zn/FeTotal ratio (> 0.01) are relevant factors which have favoured the precipitation of these minerals. Moreover, the Si, Al, P, B, and F activities might be high, favouring the magmatic crystallization of such exotic mineral phases together with Be-rich cordierite, F-rich micas, sillimanite and Al-rich phosphates. In fact, the interplay between the silica and alumina activities likely controls the stabilization and the preferential crystallization of gahnite + chrysoberyl or beryl + chrysoberyl assemblages in mm-sized microdomains. The P-T crystallization conditions are constrained by the muscovite and sillimanite stability fields and the minimum granite Al2O3-saturated solidus, and have been estimated at temperatures between 670 and 700 °C, and pressures between 1 and 2 kbar.

  7. Provenance and metamorphic PT conditions of Cryogenian-Ediacaran metasediments from the Kid metamorphic complex, Sinai, NE Arabian-Nubian Shield: Insights from detrital zircon geochemistry and mineral chemistry

    NASA Astrophysics Data System (ADS)

    El-Bialy, Mohammed Z.; Ali, Kamal A.; Abu El-Enen, Mahrous M.; Ahmed, Ahmed H.

    2015-12-01

    The Malhaq and Um Zariq formations occupy the northern part of the Neoproterozoic Kid metamorphic complex of SE Sinai, NE Arabian-Nubian Shield. This study presents new mineral chemistry data and LA-ICP-MS analyses of the trace element concentrations on zircons separated from metapelites from these formations. The detrital zircons of Um Zariq Formation are more enriched in ΣREE, whereas Malhaq Formation zircons are markedly HREE-enriched with strongly fractionated HREE patterns. The quite differences in the overall slope and size of the Eu and Ce anomalies between REE patterns of the two zircon suites provide a robust indication of different sources. The Ti-in-zircon thermometer has revealed that the zircons separated from Malhaq Formation were crystallized within the 916-1018 °C range, while those from Um Zariq Formation exhibit higher range of crystallization temperatures (1084-1154 °C). The detrital zircons of Malhaq Formation were derived mainly from mafic source rocks (basalt and dolerite), whereas Um Zariq Formation zircons have varied and more evolved parent rocks. Most of the investigated zircons from both formations are concluded to be unaltered magmatic that were lately crystallized from a high LREE/HREE melt. All the studied detrital zircon grains show typical trace elements features of crustal-derived zircons. All of the Um Zariq Formation and most of Malhaq Formation detrital zircons are geochemically discriminated as continental zircons. Both formation metapelites record similar, overlapping peak metamorphic temperatures (537-602 °C and 550-579 °C, respectively), and pressures (3.83-4.93 kbar and 3.69-4.07 kbar, respectively). The geothermal gradient, at the peak metamorphic conditions, was quite high (37-41 °C/km) corresponding to metamorphism at burial depth of 14-16 km. The peak regional metamorphism of Um Zariq and Malhaq formations is concluded to be generated during extensional regime and thinning of the lithosphere in an island arc

  8. Fluid-driven destabilization of REE-bearing accessory minerals in the granitic orthogneisses of North Veporic basement (Western Carpathians, Slovakia)

    NASA Astrophysics Data System (ADS)

    Ondrejka, M.; Putiš, M.; Uher, P.; Schmiedt, I.; Pukančík, L.; Konečný, P.

    2016-02-01

    A variety of rare earth elements-bearing (REE) accessory mineral breakdowns were identified in granitic orthogneisses from the pre-Alpine basement in the Veporic Unit, Central Western Carpathians, Slovakia. The Ordovician granitic rocks were subjected to Variscan metamorphic-anatectic overprint in amphibolite facies. Chemical U-Th-Pb dating of monazite-(Ce) and xenotime-(Y) reveal their primary magmatic Lower to Middle Ordovician age (monazite: 472 ± 4 to 468 ± 6 Ma and xenotime: 471 ± 13 Ma) and/or metamorphic-anatectic Variscan (Carboniferous, Visean) age (monazite: 345 ± 3 Ma). Younger fluid-rock interactions caused breakdown of primary magmatic and/or metamorphic-anatectic monazite-(Ce), xenotime-(Y), fluorapatite and allanite-(Ce). Fluid-induced breakdown of xenotime-(Y) produced numerous tiny uraninite inclusions within the altered xenotime-(Y) domains. The monazite-(Ce) breakdown produced secondary egg-shaped coronal structures of different stages with well-developed concentric mineral zones. Secondary sulphatian monazite-(Ce) (up to 0.15 apfu S) occasionally formed along fluorapatite fissures. Localized fluorapatite and monazite-(Ce) recrystallization resulted in a very fine-grained, non-stoichiometric mixture of REE-Y-Fe-Th-Ca-P-Si phases. Finally, allanite-(Ce) decomposed to secondary REE carbonate minerals (members of the bastnäsite and synchysite groups) and calcite in some places. Although the xenotime alteration and formation of uraninite inclusions is believed to be the result of dissolution-reprecipitation between early magmatic xenotime and late-magmatic granitic fluids, the monazite, apatite and allanite breakdowns were driven by metamorphic hydrothermal fluids. While earlier impact of post-magmatic fluids originated probably from Permian acidic volcanic and microgranitic veins crosscutting the orthogneisses, another fluid-rock interaction event most likely occurred during Late Cretaceous metamorphism in the Veporic basement and covering

  9. Fluid-driven destabilization of REE-bearing accessory minerals in the granitic orthogneisses of North Veporic basement (Western Carpathians, Slovakia)

    NASA Astrophysics Data System (ADS)

    Ondrejka, M.; Putiš, M.; Uher, P.; Schmiedt, I.; Pukančík, L.; Konečný, P.

    2016-10-01

    A variety of rare earth elements-bearing (REE) accessory mineral breakdowns were identified in granitic orthogneisses from the pre-Alpine basement in the Veporic Unit, Central Western Carpathians, Slovakia. The Ordovician granitic rocks were subjected to Variscan metamorphic-anatectic overprint in amphibolite facies. Chemical U-Th-Pb dating of monazite-(Ce) and xenotime-(Y) reveal their primary magmatic Lower to Middle Ordovician age (monazite: 472 ± 4 to 468 ± 6 Ma and xenotime: 471 ± 13 Ma) and/or metamorphic-anatectic Variscan (Carboniferous, Visean) age (monazite: 345 ± 3 Ma). Younger fluid-rock interactions caused breakdown of primary magmatic and/or metamorphic-anatectic monazite-(Ce), xenotime-(Y), fluorapatite and allanite-(Ce). Fluid-induced breakdown of xenotime-(Y) produced numerous tiny uraninite inclusions within the altered xenotime-(Y) domains. The monazite-(Ce) breakdown produced secondary egg-shaped coronal structures of different stages with well-developed concentric mineral zones. Secondary sulphatian monazite-(Ce) (up to 0.15 apfu S) occasionally formed along fluorapatite fissures. Localized fluorapatite and monazite-(Ce) recrystallization resulted in a very fine-grained, non-stoichiometric mixture of REE-Y-Fe-Th-Ca-P-Si phases. Finally, allanite-(Ce) decomposed to secondary REE carbonate minerals (members of the bastnäsite and synchysite groups) and calcite in some places. Although the xenotime alteration and formation of uraninite inclusions is believed to be the result of dissolution-reprecipitation between early magmatic xenotime and late-magmatic granitic fluids, the monazite, apatite and allanite breakdowns were driven by metamorphic hydrothermal fluids. While earlier impact of post-magmatic fluids originated probably from Permian acidic volcanic and microgranitic veins crosscutting the orthogneisses, another fluid-rock interaction event most likely occurred during Late Cretaceous metamorphism in the Veporic basement and covering

  10. High-grade metamorphism during Archean-Paleoproterozoic transition associated with microblock amalgamation in the North China Craton: Mineral phase equilibria and zircon geochronology

    NASA Astrophysics Data System (ADS)

    Yang, Qiong-Yan; Santosh, M.; Tsunogae, Toshiaki

    2016-10-01

    Metamorphic regimes in Archean terranes provide important keys to the plate tectonic processes in early Earth. The North China Craton (NCC) is one of the ancient continental nuclei in Asia and recent models propose that the cratonic architecture was built through the assembly of several Archean microcontinental blocks into larger crustal blocks. Here we investigate garnet- and pyroxene-bearing granulite facies rocks along the periphery of the Jiaoliao microcontinental block in the NCC. The garnet-bearing granulites contain peak mineral assemblage of garnet + clinopyroxene + orthopyroxene + magnetite + plagioclase + quartz ± biotite ± ilmenite. Mineral phase equilibria computations using pseudosection and geothermobarometry suggest peak P-T condition of 800-830 °C and 7-8 kbar for metamorphism. Isopleths using XMg of orthopyroxene and XCa of garnet in another sample containing the peak mineral assemblage of garnet + orthopyroxene + quartz + magnetite ± fluid yield peak P-T conditions of 860-920 °C and 11-14 kbar. Geochemical data show tonalitic to granodioritic composition and arc-related tectonic setting for the magmatic protoliths of these rocks. Zircon LA-ICP-MS analyses yield well-defined discordia with upper intercept ages of 2562 ± 20 Ma (MSWD = 0.94) and 2539 ± 21 Ma (MSWD = 0.59) which is correlated with the timing of emplacement of the magmatic protolith. A younger group of zircons with upper intercept ages of 2449 ± 41 Ma (MSWD = 0.83); N = 6 as 2449 ± 41 Ma (MSWD = 0.83; N = 6) and 2480 ± 44 Ma (MSWD = 1.2; N = 9) constrains the timing of metamorphism. Zircon Lu-Hf data show dominantly positive εHf(t) values (up to 8.5), and yield crustal residence ages (TDMC) in the range of 2529 to 2884 Ma, suggesting magma sources from Meso-Neoarchean juvenile components. The high temperature and medium to high pressure metamorphism is considered to have resulted from the subduction-collision tectonics associated with microblock amalgamation in the NCC at

  11. U-Pb Dating of Zircons and Phosphates in Lunar Meteorites, Acapulcoites and Angrites

    NASA Technical Reports Server (NTRS)

    Zhou, Q.; Zeigler, R. A.; Yin, Q. Z.; Korotev, R. L.; Joliff, B. L.; Amelin, Y.; Marti, K.; Wu, F. Y.; Li, X. H.; Li, Q. L.; Lin, Y. T.; Liu, Y.; Tang, G. Q.

    2012-01-01

    Zircon U-Pb geochronology has made a great contribution to the timing of magmatism in the early Solar System [1-3]. Ca phosphates are another group of common accessory minerals in meteorites with great potential for U-Pb geochronology. Compared to zircons, the lower closure temperatures of the U-Pb system for apatite and merrillite (the most common phosphates in achondrites) makes them susceptible to resetting during thermal metamorphism. The different closure temperatures of the U-Pb system for zircon and apatite provide us an opportunity to discover the evolutionary history of meteoritic parent bodies, such as the crystallization ages of magmatism, as well as later impact events and thermal metamorphism. We have developed techniques using the Cameca IMS-1280 ion microprobe to date both zircon and phosphate grains in meteorites. Here we report U-Pb dating results for zircons and phosphates from lunar meteorites Dhofar 1442 and SaU 169. To test and verify the reliability of the newly developed phosphate dating technique, two additional meteorites, Acapulco, obtained from Acapulco consortium, and angrite NWA 4590 were also selected for this study as both have precisely known phosphate U-Pb ages by TIMS [4,5]. Both meteorites are from very fast cooled parent bodies with no sign of resetting [4,5], satisfying a necessity for precise dating.

  12. Magma evolution as seen through zircon geochemistry: an example from the Southern Adamello Batholith, N. Italy

    NASA Astrophysics Data System (ADS)

    Broderick, C.; Schaltegger, U.; Gerdes, A.; Frick, D.; Guenther, D.; Brack, P.

    2012-04-01

    Zircon is an ubiquitous accessory mineral often used for U-Pb geochronology but is also an important recorder of geochemical information. The trace element and isotopic characteristics of zircon yield potential for tracking changes in an evolving magma through time. With recent advances in U-Pb zircon geochronology, 10-100 ka to Ma timescales are observed for incremental pluton construction (Michel et al., 2008, Schaltegger et al., 2009). In observed 100 ka timescales of zircon crystallization, can zircon record the processes that produce trace element variations in a magma? This study focuses on the Val Fredda Complex (VFC) in the southern tip of the 43 to 33 Ma Adamello batholith, N. Italy. The VFC displays complex relationships among mafic melts that were injected into solidifying felsic magmas. Single zircon crystals were dated using CA-ID-TIMS. With permil uncertainties on 206Pb/238U zircon dates, zircons reveal complexities within single populations. The mafic units crystallized potential autocrystic zircons over a duration of 100 - 150ka, whereas the felsic units record up to 200ka of zircon crystallization. In order to understand these complex zircon populations, we analyzed Hf isotopes and trace elements, on the same volume of zircon used for U-Pb dating, following the TIMS-TEA method (Schoene et al., 2010). This detailed zircon study will allow us to look at how magmas are evolving with time. Hf isotopes of VFC mafic zircons reveal distinct ɛHf values between the three mafic units and their ɛHf values remain consistent through time, whereas the VFC felsic units record more complexity in their ɛHf values. We observe changes such as increasing and slight decreases in ɛHf with time which suggest different processes are occurring to produce the different felsic units. Trace element ratios in zircon reveal differences which allow us to make distinctions between felsic and mafic units (e.g. Th/U, (Lu/Gd)N, REEs). The VFC records 200 ka of zircon

  13. Geochronology of the Martian meteorite Zagami revealed by U-Pb ion probe dating of accessory minerals

    NASA Astrophysics Data System (ADS)

    Zhou, Qin; Herd, Christopher D. K.; Yin, Qing-Zhu; Li, Xian-Hua; Wu, Fu-Yuan; Li, Qiu-Li; Liu, Yu; Tang, Guo-Qiang; McCoy, Timothy J.

    2013-07-01

    The precise chronology of geological events on Mars is hampered by the lack of absolute ages for the Martian timescale, and the significant uncertainties that result from the extrapolation of the lunar timescale to Mars (Hartmann and Neukum, 2001). Martian meteorites represent the only samples of Mars currently available. Attempts to identify source craters for the meteorites have thus far proven inconclusive (Hamilton et al., 2003; Lang et al., 2009; Mouginis-Mark and Boyce, 2012>), precluding their use in constraining the absolute Martian timescale. The majority of the known Martian meteorites are basalts ("shergottites"); all dated shergottites have mineral separate (Rb-Sr or Sm-Nd) ages of <600 Ma (Borg et al., 2005). Here we report a 238U/206Pb age of 182.7±6.9 Ma by ion microprobe analysis of baddeleyite (ZrO2) grains in the Zagami shergottite. There is no correlation between discordancy and baddeleyite grain location relative to shock metamorphism. Mineral petrography demonstrates that baddeleyite is the result of late-stage igneous crystallization, and Raman spectroscopy shows that baddeleyite has not been transformed by shock into preservable high-pressure polymorphs. Supported by an age of 153±81 Ma for phosphate grains, obtained using the same method, we conclude that Zagami crystallized at ~180 Ma, in agreement with previous results from mineral separate geochronology. Therefore, the shergottites represent igneous rocks preferentially ejected from young terrains on Mars in a small number of ejection events.

  14. U-Th-Pb and 230Th/ 238U disequilibrium isotope systematics: Precise accessory mineral chronology and melt evolution tracing in the Alpine Bergell intrusion

    NASA Astrophysics Data System (ADS)

    Oberli, Felix; Meier, Martin; Berger, Alfons; Rosenberg, Claudio L.; GierÉ, Reto

    2004-06-01

    In order to investigate the potential of combined Th-U-Pb isotope and 230Th/ 238U disequilibrium systematics for tracing magmatic crystallization and melt evolution, conventional high-resolution single-crystal TIMS techniques have been applied to zircon, titanite and fragments of geochemically characterized growth zones of allanite. These minerals were extracted from a single tonalite specimen collected from the feeder zone of the Tertiary Bergell pluton (Southern Steep Belt, S Switzerland/N Italy). The isotopic results document an extended history of crystallization and melt evolution of at least 5 Ma, with well-resolved zircon ages defining an early interval of 33.0 to 32.0 Ma, followed by crystallization of zoned allanite from 32.0 to 28.0 Ma and formation of magmatic epidote possibly as late as 26 Ma. Trace and major element patterns in zoned allanite closely mirror melt evolution, characterized by increase of U concentration and sharp decrease of Th and LREE, reflecting early crystallization of phases low in U and, in particular, the dominating control by allanite precipitation. Preservation of substantial quantities of excess 206Pb derived from initial excess 230Th in all analyzed allanite grains indicates that their isotopic systems have not been reset by loss of radiogenic Pb during prolonged residence at magmatic conditions and regional-metamorphic cooling, and that the measured sequence of 208Pb/ 232Th dates translates into a real age sequence. Major loss of radiogenic Pb from compositionally zoned allanite by volume diffusion would have resulted in a data pattern grossly different from the observed one, as demonstrated by numerical modeling of 232Th- 208Pb- 238U- 230Th- 206Pb isotopic evolution. The results therefore suggest closure temperatures ≥700°C for magmatic allanite. Quantification of 230Th/ 238U disequilibrium relationships reveals a smooth, initially steep decrease of Th/U in the magma from values of 2.9 at 32.0 Ma to < 0.1 at 28.0 Ma in

  15. Rejuvenation effects during plastic deformation of Zircon: geochronological implications

    NASA Astrophysics Data System (ADS)

    Kovaleva, Elizaveta; Klötzli, Urs

    2013-04-01

    Zircon is one of the most stable accessory minerals known on the Earth; it was believed that zircon isotopic ages mostly record primary igneous crystallization events. It is true until the mineral is not affected by plastic deformation or other disturbing events during its life after crystallization. Zircon may deform by the recovery/subgrain rotation recrystallisation that indicates formation and migration of dislocations under crustal conditions. Deformation occurs at depth due to stresses associated with collision of the phases, and forms such microstructures as low-angle boundaries (Reddy et al., 2007). Low-angle boundaries act as fluid migration paths and elements diffusion paths. Facilitating Pb, Ti, U, Th and trace elements mobility in the crystalline zircon, these structures can change chemical, REE and isotopic composition of certain grain's parts (Reddy and Timms, 2010) and lead to isotopic resetting in the mineral domains. Since the isotopic age of the domains of single crystal can vary, it should be possible to recognize and interpret this variation and distinguish the timing of different high-temperature deformation events. Zircon can preserve low-angle boundaries and associated age disturbance under lower-crust temperatures for billions of years (Moser et al., 2009). Electron backscatter diffraction (EBSD) allows us to make microstructural-crystallographic analyses in order to measure the crystallographic orientations in crystalline material. EBSD mapping is supposed to be able to constrain potential diffusion pathways in minerals. It can indicate areas of damaged crystalline structure, helps to examine substructures of minerals used in radiometric dating and to assess the potential for resetting of ages by deformation events (Reddy et al., 2007). In this research we are trying to answer a list of questions, related to isotopic resetting due to deformation: What is the behavior of zircons which were plastically deformed during metamorphic

  16. Geochemical signatures in zircons as probes of the impact history of the inner solar system

    NASA Astrophysics Data System (ADS)

    Hopkins, Michelle Diane

    Understanding the origin and evolution of the planets requires better constraints on the timing and intensity of early thermal events in the asteroid belt and Moon, including the proposed "Late Heavy Bombardment" (LHB) at ca. 3900 Ma. Both the eucrite meteorites (from asteroid 4 Vesta) and lunar impact breccias contain accessory minerals (e.g. zircon, apatite, baddeleyite, zirconolite) with U-Pb ages that may not have been wholly re-set by thermal events subsequent to their original formation; many of these pre-date the LHB epoch and yield complex histories attributable to multiple thermal events of uncertain affinity. Further detailed geochronological analyses are therefore warranted to uncover a cryptic record of "pre-LHB" bombardments. Zircons are useful in this regard because they are cited as the most reliable chronometers despite (sometimes significant) thermal metamorphism. A suite of criteria used to elucidate the petrogenetic history of zircon include: determination whether they are the products of a purely crustal igneous process; crystallized from impact melts; or experienced diffusion-controlled age resetting from impact shock-heating resulting in the partial re-equilibration of primary igneous zircon. Geochemical tools to distinguish between these different scenarios include U-Pb geochronology, trace element geochemistry, Ti-in-zircon thermometry and zircon-melt trace element partition modeling. Ultra-high resolution (sub-μm) U-Th-Pb depth profiles in eucritic zircons reveal different age domains correlative to mineral chemistry in cores and mantles within individual zircons. Results from eucrite zircons confirm previous ages determined for the solidification 4 Vesta's crust within a few million years after the formation of CAIs (4561+/-13 Ma), while younger ages may be the result of either shock metamorphism via impact heating, or are associated with protracted basaltic magmatism. Furthermore, U-Th-Pb-Ti abundances for 106 lunar zircons from lunar

  17. Trace elements in corundum, chrysoberyl, and zircon: Application to mineral exploration and provenance study of the western Mamfe gem clastic deposits (SW Cameroon, Central Africa)

    NASA Astrophysics Data System (ADS)

    Kanouo, Nguo Sylvestre; Ekomane, Emile; Yongue, Rose Fouateu; Njonfang, Emmanuel; Zaw, Khin; Changqian, Ma; Ghogomu, Tanwi Richard; Lentz, David R.; Venkatesh, Akella Satya

    2016-01-01

    Trace element abundances in three indicator minerals (corundum, chrysoberyl, and zircon grains) from the western Mamfe gem placers, as determined by LA-ICP-MS analytical techniques, are shown to be sensitive to their crystallization conditions and source rock types. Corundum is dominantly composed of Al (standardized at 529,300 ppm), Fe (2496-12,899 ppm), and Ti (46-7070 ppm). Among element ratios, Fe/Mg (73-1107), Fe/Ti (0.5-245.0), Ti/Mg (1-175), and Ga/Mg (4-90) are generally higher whereas, Cr/Ga (<0.072) is low. The Fe (≤12,899), Ga (≤398), Mg (2-62), Cr (1.1-33.0), and V (3.0-93.0) contents (in ppm) mostly typify corundum grains formed in magmatic rocks, although some are metamorphic affiliated. A very higher Ti and significantly low Ga, Ta and Nb contents in some blue grains, suggest interesting concentrations of those high-tech metals in their source rocks. Chrysoberyl is dominantly composed of Al (standardized at 425,000 ppm) and Be (62701-64371 ppm). Iron (7605-9225 ppm), Sn (502-3394 ppm), and Ti (33-2251 ppm) contents are high, whereas Ga (333-608 ppm), Ta (<456.0 ppm), and Nb (<3.0 ppm) are significantly low. The high (Be and Sn) and significantly low Ga-Rb abundances, and Ta > Nb in the western Mamfe chrysoberyls show that they were crystallized in granitic pegmatites, with some of those source rocks being enriched in Ta and Sn. Zirconium oxide (ZrO2: standardized at 66.1 wt.%)) is the only major oxide in analysed coarse-grained zircons. Within the minor elementary suites: Hf (4576-12,565 ppm) and Y (48-2805 ppm) contents are significantly high. The trace element suites include: Th (7-1565 ppm), U (13-687 ppm), and ∑REE (50-2161 ppm), whose values are significantly low. The (Yb/Sm)N, Ce/Ce*, and Eu/Eu* anomalies range from 1.0 to 227.0, 0 to 308, and 0.08 to 1.7 respectively. They are Hf-Y-HREE enriched and depleted zircons mainly crystallized in magmatic oxidized environments. They were mainly sorted from granitoids, syenites and kimberlites.

  18. Maruyamaite, a new K-dominant tourmaline coexisting with diamond -an important accessory mineral in UHP rocks

    NASA Astrophysics Data System (ADS)

    Stock, M. J.; Humphreys, M.; Smith, V.; Pyle, D. M.; Isaia, R.

    2014-12-01

    The apatite crystal structure is capable of incorporating H2O, F and Cl, as well as trace CO2 and sulphur. These can be related to parental magma compositions through application of a series of pressure and temperature-dependent exchange reactions (Piccoli and Candela, 1994), permitting apatite crystals to preserve a record of all major volatile species in the melt. Furthermore, due to the general incompatibility of P in other rock-forming minerals, apatite is ubiquitous in igneous systems and often begins crystallising early, such that apatite inclusions within phenocrysts record melt volatile contents throughout magmatic differentiation. In this work, we compare the compositions of apatite inclusions and microphenocrysts with pyroxene-hosted melt inclusions from the Astroni 1 eruption of Campi Flegrei, Italy. These data are coupled with magmatic differentiation models (Gualda et al., 2012), experimental volatile solubility data (Webster et al., 2014) and thermodynamic models of apatite compositional variations (Piccoli and Candela, 1994) to determine a time-series of magmatic volatile evolution in the build-up to eruption. We find that apatite halogen/OH ratios decreased through magmatic differentiation, while melt inclusion F and Cl concentrations increased. Melt inclusion H2O contents are constant at ~2.5 wt%. These data are best explained by volatile-undersaturated differentiation over most of the crystallisation history of the Astroni 1 melt, with melt inclusion H2O contents reset during ascent, due to rapid H diffusion through the phenocryst hosts (Woods et al., 2000). Given the rapid diffusivity of volatiles in apatite (Brenan, 1993), preservation of undersaturated compositions in microphenocrysts suggests that saturation was only achieved a few days to months before eruption and that it may have been the transition into a volatile-saturated state that ultimately triggered eruption. Piccoli and Candela, 1994. Am. J. of Sc., 294, 92-135. Gualda et al., 2012

  19. Timing and conditions of high-pressure metamorphism in the western Grenville Province: Constraints from accessory mineral composition and phase equilibrium modeling

    NASA Astrophysics Data System (ADS)

    Marsh, Jeffrey H.; Culshaw, Nicholas G.

    2014-07-01

    Previous geochronological analyses of high pressure (HP) metamorphic rocks in the western Grenville Province, Ontario, Canada have yielded precise U-Pb zircon ages; however, uncertainty has remained as to whether these ages represent the timing of HP metamorphism or the granulite/amphibolite facies overprint accompanying exhumation to a hot middle orogenic crust. Detailed study of these HP rocks, involving garnet, rutile, and zircon trace element analysis, phase equilibrium modeling, and zircon U-Pb geochronology, has yielded much improved constraints on the timing and conditions of HP metamorphism. Zircon from five of the six HP samples yield anchored discordia upper intercept and 207Pb/206Pb weighted average ages between 1097 and 1085 Ma, and typically have trace element compositions consistent with growth in a garnet-rich, plagioclase-poor eclogite-type assemblage (i.e. no negative Eu anomaly and flat HREE trends). Titanium-in-zircon and Zr-in-rutile thermometry indicates that the range of zircon crystallization temperatures for most samples (643-767 °C) is close to that of rutile inclusions in garnet (668-753 °C) and matrix rutile (690-772 °C). Phase relations in a pseudosection calculated for the sample that best preserves the HP assemblage indicate that: (1) the stability field for the inclusions observed in garnet and kyanite is between 11.5 < P < 14 kbar and 600 < T < 700 °C, and (2) zircon and rutile crystallization temperatures intersect the inferred HP assemblage field (Grt + Cpx + Ky + Rt + Hbl + Qtz) and garnet and kyanite modal isopleths at P > ~ 15 kbar, indicating that the ca. 1090 Ma zircon ages date metamorphism at eclogite facies conditions. Thus, the deep burial of mafic lower crust that resulted in HP metamorphism in the western CGB occurred just prior to the main "Ottawan" phase of continental collision in the western Grenville Province (ca. 1080-1040 Ma).

  20. Early Cretaceous U-Pb zircon ages for the Copiapó plutonic complex and implications for the IOCG mineralization at Candelaria, Atacama Region, Chile

    NASA Astrophysics Data System (ADS)

    Marschik, Robert; Söllner, Frank

    2006-12-01

    Four of the major plutons in the vicinity of the Candelaria mine (470 Mt at 0.95% Cu, 0.22 g/t Au, 3.1 g/t Ag) and a dike-sill system exposed in the Candelaria open pit have been dated with the U-Pb zircon method. The new geochronological data indicate that dacite magmatism around 123 Ma preceded the crystallization of hornblende diorite (Khd) at 118 ± 1 Ma, quartz-monzonite porphyry (Kqm) at 116.3 ± 0.4 Ma, monzodiorite (Kmd) at 115.5 ± 0.4 Ma, and tonalite (Kt) at 110.7 ± 0.4 Ma. The new ages of the plutons are consistent with field relationships regarding the relative timing of emplacement. Plutonism temporally overlaps with the iron oxide Cu-Au mineralization (Re-Os molybdenite ages at ˜115 Ma) and silicate alteration (ages mainly from 114 to 116 and 110 to 112 Ma) in the Candelaria-Punta del Cobre district. The dated dacite porphyry and hornblende diorite intrusions preceded the ore formation. A genetic link of the metallic mineralization with the quartz-monzonite porphyry and/or the monzodiorite is likely. Both of these metaluminous, shoshonitic (high-K) intrusions could have provided energy and contributed fluids, metals, and sulfur to the hydrothermal system that caused the iron oxide Cu-Au mineralization. The age of the tonalite at 110.7 Ma falls in the same range as the late alteration at 110 to 112 Ma. Tonalite emplacement may have sustained existing or driven newly developed hydrothermal cells that caused this late alteration or modified 40Ar/39Ar and K/Ar systematic in some areas.

  1. Constraining the Timescales of Magmatic Differentiation with U-Pb Zircon Geochronology

    NASA Astrophysics Data System (ADS)

    Bucholz, C. E.; Eddy, M. P.; Jagoutz, O. E.; Bowring, S. A.

    2015-12-01

    Quantifying the timescales of magmatic differentiation is critical to understand the rate at which silicic plutonic and volcanic rocks form. However, directly dating this process is difficult because locations with both clear evidence for fractional crystallization and the accessory phases necessary for radiometric dating (e.g. zircon) are rare. This study focuses on the Dariv Igneous Complex in western Mongolia where early saturation of zircon in a suite of cogenetic, upper crustal (<0.5 GPa) igneous rocks ranging from biotite-bearing ultramafic cumulates through to evolved granitoids and late stage felsic dikes allows for dating of magmatic differentiation through U-Pb geochronology for the first time. Notably, zircon is an early crystallizing mineral in the Dariv Igneous Complex, first appearing in the ultramafic cumulates, likely due to the high-Zr contents and alkaline nature of the crystallizing parental melt. Detailed textural and petrographic observations confirm that zircon is magmatic in origin and crystallized either before or contemporaneously with the volumetrically dominant mineral phases. Indistinguishable crystallization ages from Th-corrected 206Pb/238U dates of zircons from 5 samples across the sequence indicate that fractionation from a basalt to high silica (>65 wt.% SiO2) melt occurred in ≤300 ka between 502-503 Ma. If crystallization rates in crustal intrusions are primarily a function of cooling, rates of fractionation will be strongly dependent on the size and depth of the magmatic system, as well as, the dynamics of magma chamber replenishment. Therefore, the Dariv Igneous Complex, which crystallized at relatively shallow, cool levels in the crust, represents an end-member constraint for timescales associated with fractional crystallization of a basaltic melt. Fractional crystallization of mantle-derived basalts in the lower crust may occur on more protracted timescales due to greater ambient temperatures at depth and repeated influx of

  2. Age of nephrite-bearing dikes of the Uzunkyr Belt (South Urals): Local U-Pb isotope analysis of zircon and Sr-Nd isotope data of rock-forming minerals

    NASA Astrophysics Data System (ADS)

    Arkhireev, I. E.; Makagonov, E. P.; Belyatskii, B. V.; Maslennikov, V. V.

    2012-01-01

    Through local U-Pb isotope analysis of zircon and Sir-Need data on rock-forming minerals, the age of nephrite-bearing monzonite-diorite dikes of the Uzunkyr Belt has been determined. The derived datings coincide with known geological events that took place in the Phanerozoic on the territory of the South Urals. Xenogenic zircons prove the participation of the Upper Ordovician units in the tectonic structure of the studied area. Devonian zircons are associated with assimilation of subvolcanic rocks which are middle and basic in composition and whose formation time correlates with the appearance of the subduction zone with the Magnitogorsk island arc above it. Early Carboniferous datings indicate the relationship between dike formation and formation of the continental arc-shaped structure to which the Syrostan massif (monzodiorite-granite formation) belongs. The age range of the Uzunkyr nephrite-bearing dikes coincides with that of intrusives (350-336 Ma) of the Magnitogorsk Belt, where formation of gabbro series was also changed by formation of subalkali and alkali igneous rocks. According to the analogous data on zircon datings from metamorphic rocks of the Il'menogorskii Complex, the given territory later evolved as a whole.

  3. Differential response of U-Pb systems in coexisting accessory minerals, Winnipeg River Subprovince, Canadian Shield: implications for Archean crustal growth and stabilization

    NASA Astrophysics Data System (ADS)

    Corfu, F.

    1988-03-01

    The U-Pb isotopic systems of zircon, monazite, titanite and some apatite and the Pb isotopic composition of K-feldspar have been investigated in three areas of the Winnipeg River Subprovince (WRS) of the Superior Province, Canada, in order to define the timing of magmatic and metamorphic processes in this Archean gneissic-granitoid terrain. The new data together with published results define the following stages in the evolution of the WRS: (1) an extended period of early crustal growth punctuated by the episodic generation of tonalite. New ages include 3170+20/s-5 Ma, 2875+20/s-5 Ma and 2840+20/s-5 Ma for tonalitic gneisses at Cedar Lake, Kenora and Daniels Lake, respectively. (2) This early evolution was concluded by about 2760 Ma after emplacement of tonalite-granodiorite at Cliff Lake and was followed by a period of magmatic quiescence between about 2760 and 2710 Ma that contrasts with the intensive igneous activity characterizing the evolution of neighbouring greenstone belts. (3) A major episode of magmatism, deformation and metamorphism affected the Kenora and Daniels Lake areas between about 2710 and 2700 Ma. (4) A younger event caused deformation, metasomatism and amphibolite to granulite grade metamorphism at Cedar Lake and Daniels Lake at about 2680 Ma. (5) A subsequent, protracted period of low grade activity reset or (re-)crystallized titanite and apatite defining ages that scatter between about 2640 and 2520 Ma at Cedar and Daniels Lake but not in Kenora where titanite closed by about 2690 Ma. The 2680 Ma metamorphism may have been triggered in part by crustal thickening due to nappe thrusting but the subsequent period of lower grade activity requires the protracted addition of heat and/or fluids probably derived from magmatic and metamorphic processes continuing deep in the crust. The isotopic compositions of K-feldspars are relatively homogeneous and indicate mixing of Pb evolved in different reservoirs. The general enrichment in 207Pb with respect

  4. Hydrogen diffusion in Zircon

    NASA Astrophysics Data System (ADS)

    Ingrin, Jannick; Zhang, Peipei

    2016-04-01

    Hydrogen mobility in gem quality zircon single crystals from Madagascar was investigated through H-D exchange experiments. Thin slices were annealed in a horizontal furnace flushed with a gas mixture of Ar/D2(10%) under ambient pressure between 900 ° C to 1150 ° C. FTIR analyses were performed on oriented slices before and after each annealing run. H diffusion along [100] and [010] follow the same diffusion law D = D0exp[-E /RT], with log D0 = 2.24 ± 1.57 (in m2/s) and E = 374 ± 39 kJ/mol. H diffusion along [001] follows a slightly more rapid diffusion law, with log D0 = 1.11 ± 0.22 (in m2/s) and E = 334 ± 49 kJ/mol. H diffusion in zircon has much higher activation energy and slower diffusivity than other NAMs below 1150 ° C even iron-poor garnets which are known to be among the slowest (Blanchard and Ingrin, 2004; Kurka et al. 2005). During H-D exchange zircon incorporates also deuterium. This hydration reaction involves uranium reduction as it is shown from the exchange of U5+ and U4+ characteristic bands in the near infrared region during annealing. It is the first time that a hydration reaction U5+ + OH‑ = U4+ + O2‑ + 1/2H2, is experimentally reported. The kinetics of deuterium incorporation is slightly slower than hydrogen diffusion, suggesting that the reaction is limited by hydrogen mobility. Hydrogen isotopic memory of zircon is higher than other NAMs. Zircons will be moderately retentive of H signatures at mid-crustal metamorphic temperatures. At 500 ° C, a zircon with a radius of 300 μm would retain its H isotopic signature over more than a million years. However, a zircon is unable to retain this information for geologically significant times under high-grade metamorphism unless the grain size is large enough. Refrences Blanchard, M. and Ingrin, J. (2004) Hydrogen diffusion in Dora Maira pyrope. Physics and Chemistry of Minerals, 31, 593-605. Kurka, A., Blanchard, M. and Ingrin, J. (2005) Kinetics of hydrogen extraction and deuteration in

  5. Hydrogen diffusion in Zircon

    NASA Astrophysics Data System (ADS)

    Ingrin, Jannick; Zhang, Peipei

    2016-04-01

    Hydrogen mobility in gem quality zircon single crystals from Madagascar was investigated through H-D exchange experiments. Thin slices were annealed in a horizontal furnace flushed with a gas mixture of Ar/D2(10%) under ambient pressure between 900 ° C to 1150 ° C. FTIR analyses were performed on oriented slices before and after each annealing run. H diffusion along [100] and [010] follow the same diffusion law D = D0exp[-E /RT], with log D0 = 2.24 ± 1.57 (in m2/s) and E = 374 ± 39 kJ/mol. H diffusion along [001] follows a slightly more rapid diffusion law, with log D0 = 1.11 ± 0.22 (in m2/s) and E = 334 ± 49 kJ/mol. H diffusion in zircon has much higher activation energy and slower diffusivity than other NAMs below 1150 ° C even iron-poor garnets which are known to be among the slowest (Blanchard and Ingrin, 2004; Kurka et al. 2005). During H-D exchange zircon incorporates also deuterium. This hydration reaction involves uranium reduction as it is shown from the exchange of U5+ and U4+ characteristic bands in the near infrared region during annealing. It is the first time that a hydration reaction U5+ + OH- = U4+ + O2- + 1/2H2, is experimentally reported. The kinetics of deuterium incorporation is slightly slower than hydrogen diffusion, suggesting that the reaction is limited by hydrogen mobility. Hydrogen isotopic memory of zircon is higher than other NAMs. Zircons will be moderately retentive of H signatures at mid-crustal metamorphic temperatures. At 500 ° C, a zircon with a radius of 300 μm would retain its H isotopic signature over more than a million years. However, a zircon is unable to retain this information for geologically significant times under high-grade metamorphism unless the grain size is large enough. Refrences Blanchard, M. and Ingrin, J. (2004) Hydrogen diffusion in Dora Maira pyrope. Physics and Chemistry of Minerals, 31, 593-605. Kurka, A., Blanchard, M. and Ingrin, J. (2005) Kinetics of hydrogen extraction and deuteration in

  6. Fatigue properties for the fracture strength of columnar accessory minerals embedded within metamorphic tectonites: implications for stress magnitude in continental crust at the depth of the brittle-plastic transition zone

    NASA Astrophysics Data System (ADS)

    Kimura, N.; Iwashita, N.; Masuda, T.

    2009-04-01

    1. Introduction Previous studies have compiled yield-strength profiles of continental lithosphere based on the results of laboratory measurements and numerical calculations; however, yield-strength values remain poorly constrained, especially at depths below the brittle-plastic transition zone. Recent studies by the authors have refined the microboudin technique for estimating palaeostress magnitude in the deep crust (> 10 km depth). This technique has the potential to provide important information on stress levels in the deep continental crust, an environment to which available in situ stress measurements and palaeopiezometric methods cannot be applied. In applying the microboudinage technique, obtaining an estimate of the palaeostress magnitude requires knowledge of the fracture strength of columnar accessory minerals (e.g., tourmaline, amphibole, and epidote) that are subjected to brittle fracturing during plastic deformation of the surrounding matrix minerals. The absolute magnitude of fracture strength is known to show a marked reduction in the case of fatigue fracture. Fatigue fracture falls into two categories: static fatigue and cyclic fatigue. In the field of experimental rock deformation, stress corrosion by water molecules (static fatigue) is commonly invoked as the mechanism of fatigue fracture; however, evidence of both static and cyclic fatigue has been reported from studies of natural geological samples. The present study focused on the fatigue properties of columnar accessory minerals at high temperatures, with the aim of improving the accuracy of estimates of natural palaeostress magnitude at depth in the crust. 2. Constant stress-rate test A constant stress-rate test was performed to determine the influence of static fatigue on the strength of columnar accessory minerals. The test was conducted under three-point bending with a span distance of 10 mm. Temperature conditions and the crosshead speed were set in the ranges of ambient to 600°C, and 0

  7. Accessory mineral U-Th-Pb ages and 40Ar/39Ar eruption chronology, and their bearing on rhyolitic magma evolution in the Pleistocene Coso volcanic field, California

    USGS Publications Warehouse

    Simon, J.I.; Vazquez, J.A.; Renne, P.R.; Schmitt, A.K.; Bacon, C.R.; Reid, M.R.

    2009-01-01

    We determined Ar/Ar eruption ages of eight extrusions from the Pleistocene Coso volcanic field, a long-lived series of small volume rhyolitic domes in eastern California. Combined with ion-microprobe dating of crystal ages of zircon and allanite from these lavas and from granophyre geothermal well cuttings, we were able to track the range of magma-production rates over the past 650 ka at Coso. In ??? 230 ka rhyolites we find no evidence of protracted magma residence or recycled zircon (or allanite) from Pleistocene predecessors. A significant subset of zircon in the ???85 ka rhyolites yielded ages between ???100 and 200 Ma, requiring that generation of at least some rhyolites involves material from Mesozoic basement. Similar zircon xenocrysts are found in an ???200 ka granophyre. The new age constraints imply that magma evolution at Coso can occur rapidly as demonstrated by significant changes in rhyolite composition over short time intervals (???10's to 100's ka). In conjunction with radioisotopic age constraints from other young silicic volcanic fields, dating of Coso rhyolites highlights the fact that at least some (and often the more voluminous) rhyolites are produced relatively rapidly, but that many small-volume rhyolites likely represent separation from long-lived mushy magma bodies. ?? The Author(s) 2009.

  8. Magmatic ^18O in Zircons From Gabbros and Serpentinized Peridotite at the Mid-Atlantic Ridge (ODP Leg 153)

    NASA Astrophysics Data System (ADS)

    Cavosie, A. J.; Kita, N. T.; Valley, J. W.

    2005-12-01

    Zircons from gabbros and serpentinized ultramafic rocks from the Mid-Atlantic Ridge near the Kane Transform (MARK area) drilled during Leg 153 of the Ocean Drilling Program were analyzed for δ18O in situ in rock chips by ion microprobe. The gabbros contain clinopyroxene, plagioclase, apatite, Fe-oxides, with zircon occurring primarily along grain boundaries and as inclusions in other minerals (e.g. plagioclase). The mineralogy of the serpentinites is more complex, as they are comprised predominantly of a serpentine matrix that is cross-cut by multiple generations of intrusions, including zircon-bearing magmas emplaced as cm- to mm-scale gabbroic dikes and also lower temperature hydrothermal veins. The gabbroic dikes were pervasively altered at greenschist facies conditions, leaving zircon ± apatite as the only preserved magmatic phases. In some serpentinites it is difficult to distinguish altered magmatic veins from lower temperature hydrothermal veins. Zircons in serpentinite and gabbroic samples yield average δ18O values of 4.94±0.80‰ VSMOW (2 SD, N=33 analyses on 12 grains). This value would be in high temperature, magmatic equilibrium with MORB if δ18O (WR) ~ 5.3‰, or mantle peridotite if δ18O (Ol) = ~4.8‰. Equilibrium fractionation factors for δ18O between zircon-water (Zrc-H2O) were calculated by combining fractionation factors for Zrc-quartz (Valley et al. 2003) and quartz-H2O (Clayton et al., 1972; Matsuhisa et al., 1979). Over the temperature range of the calibrated fractionation factors (i.e. 500-800°C), calculated δ18O (zircon) values would be < 1 ‰ for zircon in equilibrium with previously measured MARK hydrothermal fluids (e.g. δ18O = 2.3‰). Zircon in equilibrium with seawater with δ18O = 0.0‰ would have 2.3‰ lower values. We note that extrapolation of the Zrc-H2O fractionation factors to temperatures below the calibrations of Zrc-Qtz and Qtz-H2O (e.g. <500°C) does not yield a typical mineral-water `crossover' at lower

  9. A protracted timeline for lunar bombardment from mineral chemistry, Ti thermometry and U-Pb geochronology of Apollo 14 melt breccia zircons

    NASA Astrophysics Data System (ADS)

    Hopkins, M. D.; Mojzsis, S. J.

    2015-03-01

    New zircon U-Pb and trace element investigations from Apollo 14 lunar impact breccia sample #14311 reveal at least three distinct (Concordia, 2 σ) age populations at 4334 ± 10, 4245 ± 10 and 3953 ± 10 Ma. Titanium-in-zircon thermometry (Ti xln ) results correlated with U-Pb ages range from ~800-1200 ºC. Lattice strain models used to infer zircon versus whole-rock rare earth element contents, and partitioning calculations against lunar impact breccia component compositions, quantitatively constrain formation conditions for the different age populations. A compilation of new data with published work shows that Apollo 14 zircons older than ca. 4300 Ma formed by igneous processes associated with lunar crust formation. Compositional variability in the ca. 4240 Ma zircon age population is interpretable, however, via a mixture of inherited and melt-generated components from one or more large impacts perhaps related to a marked increase in bombardment flux. Ages from the youngest zircon group at ca. 3950 Ma coincide with the classical "late heavy bombardment" (LHB) as documented from previous lunar geochronologies. These results lend support to the idea that instead of a simple unimodal LHB scenario, or a monotonic decline in impacts, the Moon was battered by multiple cataclysms since ca. 4240 Ma. Such a "Picket fence"-like bombardment to the Moon best describes the mode and tempo of impacts that accompanied the late stages of solar system formation and giant planet migration.

  10. Contrasting zircon Hf-O isotopes and trace elements between ore-bearing and ore-barren adakitic rocks in central-eastern China: Implications for genetic relation to Cu-Au mineralization

    NASA Astrophysics Data System (ADS)

    Wang, Fangyue; Liu, Sheng-Ao; Li, Shuguang; He, Yongsheng

    2013-01-01

    The petrogenesis of Early Cretaceous adakitic intrusions in the Lower Yangtze River belt (LYRB), central-eastern China, and their genetic association with Cu-Au mineralization have recently been debated. This study presented integrated in-situ zircon U-Pb-Hf-O isotopic and trace elemental data for the LYRB adakites, and a comparison with ore-barren adakites from the south Tan-Lu fault (STLF) adjacent to the LYRB. Magmatic zircons from these two series of intrusions have U-Pb ages of 145-132 Ma and 136-132 Ma respectively. The STLF zircons have δ18O ranging from 5.6 to 6.7‰ and ɛHf(t) from - 28.8 to - 16.4, plotted within the range of global lower crustal metabasaltic xenoliths, consistent with low-radiogenic Pb of the host adakitic rocks. In contrast, both Hf and O isotopic compositions of zircons from the LYRB are greatly variable with heavier δ18O (4.7 to 9.6‰) and higher ɛHf(t) values (- 25.5 to + 2.0) compared with the STLF series. The co-variations of Hf-O isotopes in the LYRB series reflect source heterogeneity as a result of mixing of basaltic oceanic crust with sediments (10-20%), consistent with high-radiogenic Pb and enriched Sr-Nd isotopic compositions of the host adakites. The high La, U and low Ti concentrations in the LYRB zircons also imply a volatile (perhaps, CO32 --rich, carbonatite-like) source. Combined with whole-rock geochemical data, the new results further suggest contrasting origins of the LYRB and STLF adakites from subducted oceanic crust and foundering lower continental crust, respectively. The LYRB zircons have much higher ratios of Ce4 +/Ce3 + (avg.417) and Eu/Eu* (avg. 0.67) than the STLF zircons (avg. 84 and 0.44). This difference confirms that the ore-bearing adakitic magmas are more oxidized relative to the ore-barren ones. There is roughly a positive correlation between zircon Ce4 +/Ce3 + and δ18O in the LYRB series, probably indicating that the elevated fO2 was related to components enriched in heavy oxygen isotopes. A

  11. Mineral inclusions in zircons of S-type granite: implications for high pressure metamorphism history of meta-sedimentary rocks in the Huai'an terrain, North China Craton

    NASA Astrophysics Data System (ADS)

    Wang, Haozheng; Zhang, Huafeng; Zhai, Mingguo; Cui, Xiahong

    2016-04-01

    The Paleoproterozoic evolution of North China Craton (NCC) arises many argument as geologists have different viewpoints on the distribution and metamorphic history of mafic granulites and granulite facies meta-sedimentary rocks. To provide more evidence of constraining the metamorphic history of granulite facies meta-sedimentary rocks, we select granulite facies meta-sedimentary rocks and co-existing S-type granite in the Huai'an terrain to make a deep research. Magmatic zircons derived from the S-type granite reveal the magmatic age of ˜1.95 Ga and metamorphic age of ˜1.85 Ga with ɛHf(t) value of -4.5 - -0.5. The ɛHf(t) value of S-type granite and relict of garnet-sillimanite gneiss suggest that the S-type granite is generated by melting of meta-sedimentary rocks. Zircons with ages of ˜1.95 Ga and ˜1.85 Ga have the mineral inclusions of Ky + Qz + Ru + Pl and these mineral inclusions are determined by method of Laser-Raman. The ˜1.95 Ga magmatic zircons with inclusions of Ky + Qz + Ru + Pl suggest that meta-sedimentary rocks have mineral assemblages Ky + Qz + Ru + Pl. However, previous studies in the Huai'an terrain showed that almost granulite facies metamorphic condition of meta-sedimentary rocks were regarded as medium pressure by considering the Sill + Grt + Bt + Pl + Qz + Ru + Kf. Presence of kyanite instructs that meta-sedimentary rocks may experience high pressure granulite facies metamorphism. According to pseudosection calculation by using effective bulk composition of garnet-sillimanite gneiss, mineral assemblage of Grt + Ky + Pl + Bt + Qz + Ru + Kf is regarded as the peak stage of high pressure metamorphism. This mineral assemblage is occurred at field of 1033 - 1123 K and 9 - 15 Kbar and the peak pressure is around 11 - 13 Kbar, determined by the XMg and XCa isopleths of garnet. This P-T result is consistent with peak condition of high pressure mafic granulite. Considering the ˜1.95 Ga magmatic age of S-type granite generated by decompression

  12. Zircon U-Pb geochronology and Sr-Nd-Hf isotopic compositions of the Yuanzhuding granitoid porphyry within the Shi-Hang Zone, South China: Petrogenesis and implications for Cu-Mo mineralization

    NASA Astrophysics Data System (ADS)

    Zhong, Lifeng; Li, Jie; Peng, Touping; Xia, Bin; Liu, Liwen

    2013-09-01

    The Shi-Hang Zone is an important NE-SW-trending Mesozoic magmatic belt in South China, which is dominated by granites with relatively high εNd(t) values and young TDM model ages. Here, we present laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U-Pb ages, major and trace element compositions, and Sr-Nd-Hf isotope data for the Yuanzhuding porphyritic granitoids within the southwestern Shi-Hang Zone, and use these data to determine the origin of this granitoid and its relationship with Cu-Mo mineralization. Zircon U-Pb dating indicates that these granitoids were emplaced at 157.8 ± 1.1 Ma. They have initial 87Sr/86Sr ratios of 0.70941-0.71398, εNd(t) values of - 3.15 to - 2.02, and in situ zircon εHf(t) values of + 1.71 to + 6.17. Geochemically, most of them are high-K calc-alkaline and show an adakitic affinity. They are more likely emplaced in a continental arc setting related to westward subduction of the paleo-Pacific plate. Their parental magma originated chiefly from the overlying sediments of the downgoing slab, and subsequently interacted with the lithospheric mantle wedge at the temperatures of ~ 790 °C. High oxygen fugacity during magmatic evolution played a crucial role in the development of Cu-Mo mineralization within the Yuanzhuding. The discovery of the Yuanzhuding deposit implies that the Chenzhou-Huaiji fault belt is most likely prospective for mineral exploration for porphyry Cu-Mo deposits.

  13. Constraints on the timing of Co-Cu ± Au mineralization in the Blackbird district, Idaho, using SHRIMP U-Pb ages of monazite and xenotime plus zircon ages of related Mesoproterozoic orthogneisses and metasedimentary rocks

    USGS Publications Warehouse

    Aleinikoff, John N.; Slack, John F.; Lund, Karen; Evans, Karl V.; Fanning, C. Mark; Mazdab, Frank K.; Wooden, Joseph L.; Pillers, Renee M.

    2012-01-01

    The Blackbird district, east-central Idaho, contains the largest known Co reserves in the United States. The origin of strata-hosted Co-Cu ± Au mineralization at Blackbird has been a matter of controversy for decades. In order to differentiate among possible genetic models for the deposits, including various combinations of volcanic, sedimentary, magmatic, and metamorphic processes, we used U-Pb geochronology of xenotime, monazite, and zircon to establish time constraints for ore formation. New age data reported here were obtained using sensitive high resolution ion microprobe (SHRIMP) microanalysis of (1) detrital zircons from a sample of Mesoproterozoic siliciclastic metasedimentary country rock in the Blackbird district, (2) igneous zircons from Mesoproterozoic intrusions, and (3) xenotime and monazite from the Merle and Sunshine prospects at Blackbird. Detrital zircon from metasandstone of the biotite phyllite-schist unit has ages mostly in the range of 1900 to 1600 Ma, plus a few Neoarchean and Paleoproterozoic grains. Age data for the six youngest grains form a coherent group at 1409 ± 10 Ma, regarded as the maximum age of deposition of metasedimentary country rocks of the central structural domain. Igneous zircons from nine samples of megacrystic granite, granite augen gneiss, and granodiorite augen gneiss that crop out north and east of the Blackbird district yield ages between 1383 ± 4 and 1359 ± 7 Ma. Emplacement of the Big Deer Creek megacrystic granite (1377 ± 4 Ma), structurally juxtaposed with host rocks in the Late Cretaceous ca. 5 km north of Blackbird, may have been involved in initial deposition of rare earth elements (REE) minerals and, possibly, sulfides. In situ SHRIMP ages of xenotime and monazite in Co-rich samples from the Merle and Sunshine prospects, plus backscattered electron imagery and SHRIMP analyses of trace elements, indicate a complex sequence of Mesoproterozoic and Cretaceous events. On the basis of textural relationships

  14. U-Pb zircon and geochemical evidence for bimodal mid-Paleozoic magmatism and syngenetic base-metal mineralization in the Yukon-Tanana terrane, Alaska

    USGS Publications Warehouse

    Dusel-Bacon, C.; Wooden, J.L.; Hopkins, M.J.

    2004-01-01

    New SHRIMP (sensitive, high-resolution ion microprobe) U-Pb zircon ages and trace element geochemical data for mafic and felsic metaigneous rocks of the pericratonic Yukon-Tanana terrane in east-central Alaska help define the tectonic setting of mid-Paleozoic magmatism and syngenetic hydrothermal Zn-Pb-Ag mineralization along the ancient Pacific margin of North America. We compare data from similar greenschist-facies sequences of bimodal volcanic and subvolcanic rocks associated with carbonaceous and siliciclastic marine sedimentary rocks, in the Wood River area of the Alaska Range and the Salcha River area of the Yukon-Tanana Upland, and from amphibolite-facies augen gneiss and mafic gneiss (amphibolite) in the Goodpaster River area of the upland. Allowing for analytical uncertainties, igneous crystallization age ranges of 376-353 Ma, 378-346 Ma, and 374-358 Ma are indicated by 13 new SHRIMP U-Pb dates for the Wood River, Salcha River, and Goodpaster River areas, respectively. Bimodal magmatism is indicated by Late Devonian crystallization ages for both augen gneiss (371 ?? 3 and 362 ?? 4 Ma) and associated orthoamphibolite (369 ?? 3 Ma) in the upland and by stratigraphic interleaving of mafic and felsic rocks in the Alaska Range. Metabasites in all three study areas have elevated HFSE (high field strength element) and REE (rare earth element) contents indicative of generation in a within-plate (extensional) tectonic setting. Within-plate trace element signatures also are indicated for peralkaline metarhyolites that host the largest volcanogenic massive sulfide deposits of the Bonnifield district in the Wood River area and for metarhyolite tuff interlayered with the carbonaceous Nasina assemblage, which hosts sedimentary exhalative sulfide occurrences in the Salcha River area. Most of the other felsic metaigneous samples from the Alaska Range and the Yukon-Tanana Upland have geochemical signatures that are similar to those of both average upper continental crust

  15. Zircon-rutile-ilmenite froth flotation process

    SciTech Connect

    Schmidt, R.; Denham, D.L. Jr.

    1992-04-21

    This patent describes a method for separating a mixture of minerals comprising at least zircon, ilmenite and rutile. It comprises adding an acid solution to the mixture to acidify to a pH of between about 2.0 and 6.0; adding starch to the mixture to depress the ilmenite and the rutile; adding a source of fluoride ions to the mixture to provide a negative surface charge on the zircon surface to activate the zircon; adding an amine cationic collector to the mixture to float the activated zircon; subjecting the mixture containing the added acid solution, the fluoride ions, the starch and the cationic collector, to froth flotation; and withdrawing a float product comprising the zircon and a sink product comprising the ilmenite and rutile.

  16. Minerals

    MedlinePlus

    Minerals are important for your body to stay healthy. Your body uses minerals for many different jobs, including building bones, making ... regulating your heartbeat. There are two kinds of minerals: macrominerals and trace minerals. Macrominerals are minerals your ...

  17. Zircon U-Pb ages, Hf-O isotopes and trace elements of Mesozoic high Sr/Y porphyries from Ningzhen, eastern China: Constraints on their petrogenesis, tectonic implications and Cu mineralization

    NASA Astrophysics Data System (ADS)

    Wang, Fangyue; Liu, Sheng-Ao; Li, Shuguang; Akhtar, Shamim; He, Yongsheng

    2014-07-01

    The relationship between high Sr/Y (adakitic) rocks and Cu mineralization has been long recognized but the mechanism remains unclear. The Cretaceous high Sr/Y porphyries in the Ningzhen area host major Cu polymetallic deposits in the Lower Yangtze River Belt (LYRB) of eastern China. These rocks exhibit some geochemical characteristics (e.g., non-radiogenic Pb isotope ratios) that differ from adakitic rocks from adjacent locations in the LYRB. In this study, we present a study of the zircon U-Pb-Hf-O isotope and trace element compositions for five porphyries from Ningzhen to reveal their petrogenesis and how that correlates with Cu-Fe-Mo mineralization. Zircon U-Pb ages of Anjishan (Cu deposit), Tongshan (Cu-Mo deposit) and Xiangshan (Fe deposit) plutons in the Ningzhen area are 108.8 ± 1.5 Ma, 105-107 Ma and 100-105 Ma, respectively, which are significantly younger than the ore-bearing adakites (140 ± 5 Ma) in the western part of the LYRB. Zircon εHf(t) and δ18O values range from - 23.4 to - 10.6 and from 5.7 to 7.0‰, respectively, falling between subduction-related adakites from the other regions in the LYRB and delamination-related adakitic rocks from the adjacent South Tan-Lu Fault Zone. The similarities of Ce4 +/Ce3 + and Eu/Eu* ratios in zircons from Ningzhen and those from the western LYRB indicate higher oxygen fugacity in their magma sources. Ti-in-zircon thermometer yields magma temperatures of 550 to 700 °C (with an average of ~ 650 °C) for the Ningzhen porphyries, which are significantly lower than those of the South Tan-Lu Fault adakites (> 750 °C), but similar to those for the LYRB adakites (< 700 °C). In summary, the Ningzhen high Sr/Y porphyries have high Mg# (> 50), non-radiogenic Pb, enriched Sr-Nd isotopic compositions, negative zircon εHf(t), mantle-like δ18O values, high oxygen fugacities and low magma temperatures. Mafic rocks that co-exist with ore-bearing porphyries or occur as xenoliths in porphyries are widespread. We proposed

  18. U-Pb Detrital Zircon Ages From the Internal Hellenides Using LA-SF-ICP-MS

    NASA Astrophysics Data System (ADS)

    Frei, D.; Meinhold, G.

    2008-12-01

    Zircon is a common accessory phase in clastic sedimentary rocks as well as one of the most stable minerals in sedimentary environments. Investigating the age spectra of detrital zircons is important for sedimentary provenance analysis to glean information regarding ancient source areas and major magmatic events, crucial for plate-tectonic and palaeogeographic reconstructions. Furthermore, in the absence of fossil and other stratigraphic data, the youngest zircon grain in a sedimentary rock can indicate a maximum limit for the age of deposition. Laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) is a rapid, comparably inexpensive and sufficiently precise technique for in-situ Pb-Pb and U-Pb age determinations of igneous, metamorphic and detrital zircons. In this study, we applied a simple method for in-situ U-Pb age determinations of zircons using a ThermoFinnigan Element2 magnetic sectorfield ICP-MS coupled to a frequency quintupled Nd-YAG (213 nm) laser ablation system. This method takes advantage of the very high sensitivity of the magnetic sectorfied ICP-MS and allows U-Pb age dating of zircons with significantly better spatial resolution (i.e. spot diameters of 30 microns and below and a depth resolution of 15 to 20 ìm) compared to quadrupole ICP-MS based methods. For this study, samples were collected from the Serbo- Macedonian Massif and the Vardar Zone of northern Greece. Both areas belong to the Internal Hellenides. There, the relationships between different pre-Alpine crustal fragments are now masked by younger (Mesozoic to Cenozoic) complex structural and metamorphic events. This, together with the scarcity of biostratigraphic, geochronological and palaeomagnetic data, has given rise to equivocal palaeotectonic models and interpretations. Detrital zircon geochronology is used here to constrain terrane accretion processes and the provenance of crustal sources for sediments during Palaeozoic and Mesozoic times. The age and origin of

  19. The Laser Accessory Market

    NASA Astrophysics Data System (ADS)

    Desai, Ashvin

    1988-09-01

    Wandering through the exhibit hall yesterday, I noticed that if you look at the laser companies and if you look at the accessory companies, there are pretty much the same number of accessory booths as well as the laser companies. There was one difference. Laser company booths are all sexy looking, very flashy, big booths. Whereas if you look at the accessories booths, they were small, not so prominent.

  20. Advantages of reusable accessories.

    PubMed

    Wolfsen, H C

    2000-04-01

    Despite scant evidence supporting the use of disposable accessories, these devices have been widely disseminated. Manufacturers and governmental regulators, the most devout proponents of one-time use accessories, have framed the issue in economic terms-parsimonious practitioners reusing disposable accessories at the risk of cross-contamination, mechanical failure and product liability. This simplistic view represents revisionist history and ignores the long tradition of reusing these devices. This article reviews the numerous studies that support the safe and cost effective reuse of disposable and reusable accessories.

  1. A new method integrating high-precision U-Pb geochronology with zircon trace element analysis (U-Pb TIMS-TEA)

    NASA Astrophysics Data System (ADS)

    Schoene, B.; Latkoczy, C.; Schaltegger, U.; Günther, D.

    2010-12-01

    Increased precision in isotope-dilution thermal ionization mass spectrometry (ID-TIMS) U-Pb geochronology has revealed age complexities in zircon populations that require new tools for understanding how the growth of zircon is related to geologic processes. U and Pb are routinely separated from other elements in dated minerals by ion exchange separation prior to TIMS isotope measurement. We develop a method in which trace elements in the exact same volume of zircon are redissolved and analyzed using solution nebulization inductively coupled plasma sector-field mass spectrometry with matrix-matched external liquid calibration. Using <0.5 ml solution, resulting concentrations are between <1 ppt for elements such as Ti, Nb and Ta and tens of ppb for Zr. By analyzing a series of standard solutions, zircons and procedural blanks, we show that accurate measurements are performed on Zr, Hf, Y, Sc, and the HREE while low-concentration elements can be measured accurately to <5 ppt. We performed combined U-Pb ID-TIMS geochronology with trace element analysis (here called U-Pb TIMS-TEA) on zircons from eight volcanic rocks comprising several volcanic systems and one metamorphic sample. Similar to previous in situ trace element analyses, zircon geochemistry is distinct between different samples and records petrogenetic processes such as fractional crystallization, assimilation and/or magma mixing. Unique from in situ analysis, U-Pb TIMS-TEA can trace geochemical evolution in accessory minerals with adequate age precision to resolve magmatic processes in rocks at least 200 million years old. This provides a means to identify auto-, ante- and xenocrystic zircon and lead to more robust age interpretations in ID-TIMS U-Pb geochronology. One suite of Cretaceous andesitic zircons shows correlations in geochemistry and absolute time that record evolution of a magmatic system over ˜250 ka prior to eruption. Future work will combine U-Pb TIMS-TEA with solution isotopic analysis of Nd

  2. Perspectives on Precambrian basement architecture in the northern US Rocky Mountains from inherited zircons in the Idaho batholith

    NASA Astrophysics Data System (ADS)

    Gaschnig, R. M.; Vervoort, J. D.; Lewis, R.; Tikoff, B.

    2010-12-01

    Inherited accessory minerals in Phanerozoic plutons can often provide key information about Precambrian crystalline basement that is poorly exposed. Here, we present U-Pb age and Hf isotope data for Precambrian inherited zircons in the Cretaceous-Paleocene Idaho batholith, in anticipation of the IDOR (Idaho-Oregon) Earthscope Project. In situ U-Pb dating of these inherited zircons reveals major differences in the crustal architecture between the southern Atlanta and northern Bitterroot lobes of the Idaho batholith. Inheritance in the Atlanta lobe is dominated by ages of ~2.55 Ga and ~670 Ma, with the older age more prevalent in the southernmost samples. We interpret these ages to record the presence of significant Neoarchean and Neoproterozoic igneous or metaigneous rock in the subsurface since both ages can be correlated with known local bedrock exposures and xenoliths (in the case of the Neoarchean). In contrast, inherited zircons from the Bitterroot lobe yield a continuous age distribution between 1.9 and 1.4 Ga, which is remarkably similar to the detrital zircon age spectra of much of the Mesoproterozoic Belt Supergroup. Belt Supergroup rocks are the likely source of the zircon inheritance, implying that the inheritance pattern we see in the Bitterroot samples provides little new information on the crystalline basement on which the Belt Supergroup was deposited. The extent of Archean inheritance in the Atlanta lobe suggests that the Archean crust exposed in the Albion and Grouse Creek Mountains and present beneath the central and eastern Snake River Plain extends as far west as the Pre-Mesozoic continental margin and further north than previously thought, making it a potentially important piercing point in reconstructions of the Rodinian supercontinent. In situ Hf isotopic analyses of the Archean cores provide evidence for previously existing Early Archean crustal components to this crustal block, similar to components of the Wyoming Province to the east.

  3. Pan-Africa/Pan-Brazilian detrital zircons in Lower Palaeozoic schists of SW Norway - enigmatic detrital zircon U-Pb ages

    NASA Astrophysics Data System (ADS)

    Zimmermann, Udo; Bjørheim, Maren; Clark, Chris

    2013-04-01

    We present Sensitive High Resolution Ion Microprobe (SHRIMP) U-Pb zircon age data from metasedimentary rocks (schists and quartzites) located in the town of Stavanger (SW Norway). The metasedimentary sequence is composed of schists, medium grained quartz-rich metawackes and quartzites. Quartzites and meta-quartz-wackes exhibit a mylonitic fabric with newly grown fine-grained muscovite defining the fabric. Accessory minerals are zircon, allanite, detrital apatite, monazite, ilmenite, rutile and zircon. The schists are dark and dominated by quartz and feldspar in a fine chloritic and silica-rich matrix and represent the dominant lithology of the region. While quartzites and metawackes show typical geochemical characteristics for strongly reworked rocks, the schists have very low Zr/Sc and Th/Sc ratios below 0.9 and point together with other trace element ratios (La/Sc, Ti/Zr) to the strong influence of less fractionated, mafic, sources in the detritus, possibly arc derived. U-Pb ages of detrital zircon from quartzites range between 740 to 1800 Ma. There is a defined population at 1135 and 1010 Ma tentatively correlated with the Sveconorwegian orogeny. A second population at ~1450 Ma that can be related to a tectono-magmatic event during the Earliest Mesoproterozoic, also recorded in Oslo, southern Sweden and Bornholm, mapped along the proposed southern margin of Baltica. Other detrital zircons record ages between 1586 - 1664 Ma that are not related to the latter event. The oldest U-Pb detrital zircon grain age was 1796 Ma and is potentially associated with the terminal phase of the Svecofennian orogeny. Detrital zircons from the associated schists do show a similar abundance of main age clusters but the oldest found zircons dates to 2013 Ma while the maximum depositional age could be determined by grains of Cambrian to even Ordovician ages with a large 1 sigma error, as such that we rather propose a Cambrian maximum depositional age. It is possible to speculate that

  4. High-resolution tephrochronology of the Wilson Creek Formation (Mono Lake, California) and Laschamp event using 238U-230Th SIMS dating of accessory mineral rims

    USGS Publications Warehouse

    Vazquez, Jorge A.; Lidzbarski, Marsha I.

    2012-01-01

    Sediments of the Wilson Creek Formation surrounding Mono Lake preserve a high-resolution archive of glacial and pluvial responses along the eastern Sierra Nevada due to late Pleistocene climate change. An absolute chronology for the Wilson Creek stratigraphy is critical for correlating the paleoclimate record to other archives in the western U.S. and the North Atlantic region. However, multiple attempts to date the Wilson Creek stratigraphy using carbonates and tephras yield discordant results due to open-system effects and radiocarbon reservoir uncertainties as well as abundant xenocrysts. New ion microprobe 238U-230Th dating of the final increments of crystallization recorded by allanite and zircon autocrysts from juvenile pyroclasts yield ages that effectively date eruption of key tephra beds and delimit the timing of basal Wilson Creek sedimentation to the interval between 26.8±2.1 and 61.7±1.9 ka. Tephra (Ash 15) erupted during the geomagnetic excursion originally designated the Mono Lake excursion yields an age of 40.8±1.9 ka, indicating that the event is instead the Laschamp excursion. The new ages support a depositional chronology from magnetostratigraphy that indicates quasi-synchronous glacial and hydrologic responses in the Sierra Nevada and Mono Basin to regional climate change, with intervals of lake filling and glacial-snowpack melting that are in phase with peaks in spring insolation.

  5. High-resolution tephrochronology of the Wilson Creek Formation (Mono Lake, California) and Laschamp event using 238U-230Th SIMS dating of accessory mineral rims

    NASA Astrophysics Data System (ADS)

    Vazquez, Jorge A.; Lidzbarski, Marsha I.

    2012-12-01

    Sediments of the Wilson Creek Formation surrounding Mono Lake preserve a high-resolution archive of glacial and pluvial responses along the eastern Sierra Nevada due to late Pleistocene climate change. An absolute chronology for the Wilson Creek stratigraphy is critical for correlating the paleoclimate record to other archives in the western U.S. and the North Atlantic region. However, multiple attempts to date the Wilson Creek stratigraphy using carbonates and tephras yield discordant results due to open-system effects and radiocarbon reservoir uncertainties as well as abundant xenocrysts. New ion microprobe 238U-230Th dating of the final increments of crystallization recorded by allanite and zircon autocrysts from juvenile pyroclasts yield ages that effectively date eruption of key tephra beds and delimit the timing of basal Wilson Creek sedimentation to the interval between 26.8±2.1 and 61.7±1.9 ka. Tephra (Ash 15) erupted during the geomagnetic excursion originally designated the Mono Lake excursion yields an age of 40.8±1.9 ka, indicating that the event is instead the Laschamp excursion. The new ages support a depositional chronology from magnetostratigraphy that indicates quasi-synchronous glacial and hydrologic responses in the Sierra Nevada and Mono Basin to regional climate change, with intervals of lake filling and glacial-snowpack melting that are in phase with peaks in spring insolation.

  6. Imaging of trace element distribution in zircon by LA-ICP-MS: Insights into ultrahigh-pressure anatexis

    NASA Astrophysics Data System (ADS)

    Stepanov, Aleksandr; Danyushevsky, Leonid; Olin, Paul; Meffre, Sebastien; Rubatto, Daniela; Hermann, Joerg; Korsakov, Andrey

    2014-05-01

    Zircon is a key accessory mineral in Ultra High Pressure (UHP) metamorphic rocks as it is stable during the entire metamorphic evolution and it remains as a restite phase after melt extraction. Zircon contains significant amounts of REE, Th and U, elements which, at the bulk-rock scale, are strongly affected by melting at UHP conditions. Due to its refractory nature, zircon can preserve pre-melting concentrations of such elements. Moreover, zircon growth zones can be precisely dated and the Ti-in-zircon thermometer can provide a temperature record. A LA-ICP-MS imaging technique has been developed at the CODES analytical facilities at the University of Tasmania. The technique uses a set of parallel lines with spacing equaling the laser beam size. Pre-ablation of each line is essential for removing surface deposition from previous ablations. Regular measurements of the background and calibration standards are required for controlling memory effects and instrumental drift. Use of square rather than round beam shape is preferred for this application. LA-ICP-MS imaging provides spatial resolution of about 10 microns and detection limits below 1 ppm. High errors on individual measurements are compensated by large overall statistics. Here we report the successful application of this imaging technique to zircons from the Kokchetav metamorphic complex (Kazakhstan). The UHP metamorphic rocks of the Kokchetav complex experienced partial melting and melt loss at extreme conditions of 45-60 kbar and 950-1000°C. Metamorphism of metasediments produced a specific bulk rock trace element signature with depletion in LREE, Th and U. LA-ICP-MS spots analysis and LA-ICP-MS imaging reveal at least four different compositional types of zircon. Type-1 zircon cores have low Th contents and Th/U ratios and steep REE patterns. The low Th content is attributed to formation in equilibrium with monazite, which hosted a large fraction of the bulk Th. Type-2 zircons are seen as mantles with Th

  7. Ti-in-Zircon Thermometer: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Fu, B.; Cavosie, A. J.; Clechenko, C. C.; Fournelle, J.; Kita, N. T.; Lackey, J.; Page, F.; Wilde, S. A.; Valley, J. W.

    2005-12-01

    The titanium in zircon thermometer has been applied to 167 zircons from diverse rock types. These rocks include metamorphosed anorthosite and gabbro (1.15 Ga, intrusion age), and unmetamorphosed granitic pegmatite (0.9 Ga) from the Adirondack Highlands; metaluminous and peraluminous granites (114-90 Ma) of the Sierra Nevada Batholith; megacrysts from kimberlite pipes in southern Africa, Brazil, and Siberia; and detrital zircons (4.4-3.9 Ga) of metaconglomerate from Jack Hills, Western Australia. Titanium concentration in zircon was analysed using a CAMECA IMS-1280 ion microprobe (see Page et al., this volume). Spot analyses were correlated to U-Pb SHRIMP pits especially for Adirondack and Jack Hills zircons. The majority of zircons have Ti-content less than 10 ppm. Variability, in excess of analytical precision, within individual zircons is observed in about one-third of crystals. In general, there is no systematic change in Ti from core to rim (identified by cathodoluminescence) of zircons, or with regard to age, U content, Th/U ratio, or U-Pb age concordance for these non-metamict grains. The average temperatures for zircon crystallization in different rock suites using the experimental/empirical calibration of Watson and Harrison (W&H, 2005, Science 308:841), assuming the presence of rutile and quartz, are estimated to be: anorthosite 735±41°C (1SD, n=24; Ti = 10±5 ppm); metagabbro 714±31°C (n=19; Ti = 8±4 ppm); Adirondack pegmatite 500±16°C (n=5; Ti = 0.3±0.1 ppm); metaluminous and peraluminous granites from Sierra Nevada 681±67°C (n=53; Ti = 6±5 ppm) and 613±75°C (n=68; Ti = 3±3 ppm); kimberlite megacrysts 740±64°C (n=169; Ti = 14±13 ppm) (Page et al., this volume); and detrital zircons from Jack Hills metaconglomerate 718±63°C (n=64; Ti = 10±9 ppm). Most of the host rocks contain ilmenite or titanite suggesting that α(TiO2)>0.5, but rutile activity is unknown for megacrysts and detrital zircons. Pegmatite contains no Ti-rich minerals

  8. Zircon U-Pb ages and Sr-Nd-Hf isotopes of the highly fractionated granite with tetrad REE patterns in the Shamai tungsten deposit in eastern Inner Mongolia, China: Implications for the timing of mineralization and ore genesis

    NASA Astrophysics Data System (ADS)

    Jiang, Si-Hong; Bagas, Leon; Hu, Peng; Han, Ning; Chen, Chun-Liang; Liu, Yuan; Kang, Huan

    2016-09-01

    The Shamai tungsten deposit is located in the eastern part of the Central Asian Orogenic Belt (CAOB). Tungsten mineralization is closely related to the emplacement of fine- to medium-grained biotite monzogranite (G1) and porphyritic biotite monzogranite (G2) in the Shamai Granite. NW-trending joints and faults host orebodies in the Shamai Granite and Devonian hornfels. The mineralization is characterized by a basal veinlet zone progressing upwards to a thick vein zone followed by a mixed zone, a veinlet zone, and a thread vein zone at the top. The ore-related alteration typically consists of muscovite, greisen, and hornfels. In order to constrain the timing of the Shamai mineralization and discuss the ore genesis, muscovite Ar-Ar, molybdenite Re-Os, and zircon U-Pb geochronological, geochemical, and Sr-Nd-Hf isotopic studies were completed on the deposit. The U-Pb zircon dating yielded weighted mean ages of 153 ± 1 Ma for G1 and 146 ± 1 Ma for G2. Muscovite from a wolframite-bearing quartz vein yielded an Ar-Ar plateau age of 140 ± 1 Ma, whereas two molybdenite samples yielded identical Re-Os model ages of 137 ± 2 Ma. These two ages are younger than the two monzogranites, suggesting a prolonged magmatic-hydrothermal interaction during tungsten mineralization. Major and trace element geochemistry shows that both G1 and G2 are characterized by high SiO2 and K2O contents, high A/CNK values (1.08-1.40), a spectacular tetrad effect in their REE distribution patterns, and non-CHARAC (charge-and-radius-controlled) trace element behavior. This suggests that both G1 and G2 are highly differentiated peraluminous rocks with strong hydrothermal interaction. The Nd-Hf isotope data for the Shamai Granite (εNd(t) between - 1.9 and + 7.4, ɛHf(t) from 5.2 to 12.8) are largely compatible with the general scenario for much of the Phanerozoic granite emplaced in the CAOB. It is here suggested that the Shamai Granite originated from partial melting of a juvenile lower crust with

  9. Evidence of ancient cataclysm in modern sand: shock microstructures in detrital quartz, zircon, and monazite from the Vaal River, Vredefort Dome, South Africa

    NASA Astrophysics Data System (ADS)

    Cavosie, A. J.; Quintero-Mendez, R. R.; Radovan, H. A.; Moser, D. E.; Valley, J. W.

    2009-12-01

    spacing (1 to 20 μm). Many detrital shocked monazite grains contain large (up to 120μm), euhedral, oscillatory-zoned zircon inclusions that also contain PFs, and thus are the first reported shocked accessory mineral inclusions within shocked accessory grains. In addition, single grains of both zircon and monazite with granular texture were identified. This study is further proof of the concept that quartz, zircon, and monazite with pervasive shock microstructures survive the processes of erosion and sedimentary transport in modern siliciclastic sediments up to 2 billion years after an impact (Cavosie et al., 2008). These results demonstrate the large preservation potential of detrital shocked minerals for identifying the presence, timing, and target rock age for ancient impact events that may be otherwise missing from the rock record. The ubiquitous presence of quartz, zircon, and monazite in Archean-age siliciclastic rocks offers promise that traces of the lost record of impacts from the early Earth are preserved in younger sediments and await discovery. Cavosie et al., 2008, Eos Trans., 89(53), abstr. V12B-02. Cavosie et al., GSA Bulletin, in review.

  10. Topological Modeling of Metamict Zircon

    NASA Astrophysics Data System (ADS)

    Hobbs, L. W.; Zhang, Y.; Yuan, X.

    2006-05-01

    Zircon (ZrSiO4) is the most studied metamict mineral and a leading model for candidate ceramic hosts designed to encapsulate highly radioactive nuclear waste and excess plutonium. It is also emblematic of compound oxide ceramics with a potential to phase separate in the amorphized state. Several groups have carried out ab initio or molecular dynamics (MD) simulations of melt-quenched or radiation-disordered zircon. A tendency for silica tetrahedra to polymerize, implying incipient phase separation, has been noted, but adequate descriptors of the amorphous state capable of distinguishing between different disordered arrangements have not been available. This contribution details critical modifications made to empirical potentials used in MD simulations and useful improvements in modeling efficiency that have facilitated constant pressure simulations of quenched and displacement cascade-amorphized zircon. The simulated end- states have been subjected to topological assessment algorithms for enumerating coordinations, bond lengths and bond angles; counting primitive rings and identifying structure-defining local primitive-ring clusters; and assessing degree of coordination-unit polymerization. The topologies of simulated melt, melt-quenched and cascade-amorphized disordered arrangements have been found to be different and distinguishable. A two-body Born-Mayer empirical potential with ZBL short-range repulsive term was fit to major structural, elastic, thermal and dielectric properties of crystalline zircon, but it was noted that the best crystalline fit, with non-stoichiometric partial ion charges, led to unrealistic coordinations in amorphized arrangements and uncontrolled expansions in constant pressure simulations because of silica polymerization. Therefore, stoichiometrically charge-balanced partial charges were instead chosen and optimized; the optimal choice of O-1.2, Si+2.4, Zr+2.4 led to realistic coordinations (Zr 7, Si 4) and well-behaved constant

  11. Accessory oral cavity

    PubMed Central

    Gnaneswaran, Manica Ramamoorthy; Varadarajan, Usha; Srinivasan, Ramesh; Kamatchi, Sangeetha

    2012-01-01

    This is a rare case report of a patient around 11 years with the complaint of extra mouth who reported to the hospital for removal of that extra mouth. On examination there was accessory oral cavity with small upper and lower lips, seven teeth and saliva was drooling out. Under general anesthesia crevicular incision from 32 to 43 was put and labial gingiva with alveolar mucosa was reflected completely and bone exposed to lower border of mandible. There were seven teeth resembling lower permanent anterior teeth in the accessory mouth, which was excised with the accessory lips. 41 extracted and osteotomy carried out extending the incision from the extracted site and osteotomy carried out. Dermoid cyst both below and above the mylohyoid muscle and rudimentary tongue found and excised and the specimen sent for histopathological examination. The wound was closed and uneventful healing noted to the satisfaction of the patient. This is a rare and interesting case which has been documented. PMID:23833508

  12. Zircon U-Pb age, Lu-Hf isotope, mineral chemistry and geochemistry of Sundamalai peralkaline pluton from the Salem Block, southern India: Implications for Cryogenian adakite-like magmatism in an aborted-rift

    NASA Astrophysics Data System (ADS)

    Renjith, M. L.; Santosh, M.; Li, Tang; Satyanarayanan, M.; Korakoppa, M. M.; Tsunogae, T.; Subba Rao, D. V.; Kesav Krishna, A.; Nirmal Charan, S.

    2016-01-01

    The Sundamalai peralkaline pluton is one among the Cryogenian alkaline plutons occurring in the Dharmapuri Rift Zone (DRZ) of the Salem Block in the Southern Granulite Terrane (SGT) of India. Here we present zircon U-Pb age and Lu-Hf isotopic composition, mineral chemistry and geochemistry of the pluton to explore the petrogenesis and geodynamic implications. Systematic modal variation of orthoclase, Na-plagioclase, Ca-amphibole (ferro-edenite and hastingsite) and quartz developed quartz-monzonite and granite litho units in the Sundamalai pluton. Thermometry based on amphibole-plagioclase pair suggests that the pluton was emplaced and solidified at around 4.6 kbar pressure with crystallization of the major phases between 748 and 661 °C. Estimated saturation temperature of zircon (712-698 °C) is also well within this range. However, apatite saturation occurred at higher temperatures between 835 and 870 °C, in contrast with monazite saturation (718-613 °C) that continued up to the late stage of crystallization. Estimated oxygen fugacity values (log fO2: -14 to -17) indicate high oxidation state for the magma that stabilized titanite and magnetite. The magmatic zircons from Sundamalai pluton yielded a weighted mean 206Pb/238U age of 832.6 ± 3.2 Ma. Geochemically, the Sundamalai rocks are high-K to shoshonitic, persodic (Na2O/K2O ratio > 1), silica-saturated (SiO2:65-72 wt.%), and peralkaline in composition (aluminum saturation index, ASI < 1; Alkalinity index, AI < 0). The initial magma was mildly metaluminous which evolved to strongly peralkaline as result of fractional crystallization (plagioclase effect) controlled differentiation between quartz-monzonite and granite. Both rock types have high content of Na2O (5.1-6.3 wt.%), Ba (350-2589 ppm) and Sr (264-1036 ppm); low content of Y (8.7-17 ppm) and Yb (0.96-1.69 ppm); elevated ratios of La/Yb (11-46) and Sr/Y (46-69) and are depleted in Ti, with a positive Sr anomaly suggesting an adakite-like composition and

  13. Ceramic with zircon coating

    NASA Technical Reports Server (NTRS)

    Wang, Hongyu (Inventor)

    2003-01-01

    An article comprises a silicon-containing substrate and a zircon coating. The article can comprise a silicon carbide/silicon (SiC/Si) substrate, a zircon (ZrSiO.sub.4) intermediate coating and an external environmental/thermal barrier coating.

  14. Accessory fissures of the lung

    SciTech Connect

    Godwin, D.; Tarver, R.D.

    1985-01-01

    Accessory fissures of the lung are commonly observed in lung specimens, but are often unappreciated or misinterpreted in radiographs and computer tomographic (CT) scans. They usually occur at the boundaries between bronchopulmonary segments. Most common are the inferior accessory fissure, which demarcates the medial basal segment; the superior accessory fissure, which demarcates the superior segment; and the left minor fissure, which demarcates the lingula. This essay will illustrate the findings of the common accessory fissures both on plain radiographs and on CT scans.

  15. Bilateral accessory thoracodorsal artery.

    PubMed

    Natsis, Konstantinos; Totlis, Trifon; Tsikaras, Prokopios; Skandalakis, Panagiotis

    2006-09-01

    The subscapular artery arises from the third part of the axillary artery and gives off the circumflex scapular and the thoracodorsal arteries. Although anatomical variations of the axillary artery are very common, the existence of a unilateral accessory thoracodorsal artery has been described in the literature only once. There are no reports of bilateral accessory thoracodorsal artery, in the literature. In the present study, a bilateral accessory thoracodorsal artery, originating on either side of the third part of the axillary artery, is described in a 68-year-old female cadaver. All the other branches of the axillary artery had a typical origin, course, distribution and termination. This extremely rare anatomical variation apart from the anatomical importance also has clinical significance for surgeons in this area. Especially, during the dissection or mobilization of the latissimus dorsi that is partly used for coverage problems in many regions of the body and also in dynamic cardiomyoplasty, any iatrogenic injury of this accessory artery may result in ischemia and functional loss of the graft.

  16. Accessory parotid gland tumors

    PubMed Central

    Ramachar, Sreevathsa M.; Huliyappa, Harsha A.

    2012-01-01

    Tumors of accessory parotid gland are considered in the differential diagnosis of a mid cheek mass. Parotidectomy is the procedure of choice. All pathological types of parotid main gland tumors occur in the accessory parotid gland also. Presenting as a mid cheek or infrazygomatic mass, the tumors of this accessory parotid gland are notorious for recurrences, if adequate margins are not achieved. We describe two such cases of such a tumor. 40-year-old male with a slowly progressive mid cheek mass was operated by a mid cheek incision. Histopathology of the tumor was pleomorphic adenoma. Facial nerve paresis recovered complelety in 6 months. A 52-year-old female with progressive mid cheek mass who underwent parotidectomy and neck dissection by a modified Blair's incision was diagnosed with extranodal marginal zone lymphoma with focal transformation to a diffuse large B-cell lymphoma. Chemotherapy with CHOP regime was initiated. There was no recurrence at 6 months of follow-up. Lymphoma of accessory parotid gland is a very rare tumor. Standard parotidectomy incision is advocated to prevent damage to facial nerve branches. PMID:23483721

  17. Rare earth elements in synthetic zircon. 1. synthesis, and rare earth element and phosphorus doping.

    SciTech Connect

    Hanchar, J. M.; Finch, R. J.; Hoskin, W. O.; Watson, E. B.; Cherniak, D. J.; Mariano, A. N.; Chemical Engineering; George Washington Univ.; Univ. of Canterbury; Australian National Univ.; Rensselaer Polytechnic Inst.

    2001-05-01

    Sedimentary mineral assemblages commonly contain detrital zircon crystals as part of the heavy-mineral fraction. Age spectra determined by U-Pb isotopic analysis of single zircon crystals within a sample may directly image the age composition--but not the chemical composition--of the source region. Rare earth element (REE) abundances have been measured for zircons from a range of common crustal igneous rock types from different tectonic environments, as well as kimberlite, carbonatite, and high-grade metamorphic rocks, to assess the potential of using zircon REE characteristics to infer the rock types present in sediment source regions. Except for zircon with probable mantle affinities, zircon REE abundances and normalized patterns show little intersample and intrasample variation. To evaluate the actual variation in detrital zircon REE composition in a true sediment of known mixed provenance, zircons from a sandstone sample from the Statfjord Formation (North Sea) were analyzed. Despite a provenance including high-grade metasediment and granitoids and a range in zircon age of 2.82 b.y., the zircon REEs exhibit a narrow abundance range with no systematic differences in pattern shape. These evidences show zircon REE patterns and abundances are generally not useful as indicators of provenance.

  18. Iatrogenic accessory nerve injury.

    PubMed Central

    London, J.; London, N. J.; Kay, S. P.

    1996-01-01

    Accessory nerve injury produces considerable disability. The nerve is most frequently damaged as a complication of radical neck dissection, cervical lymph node biopsy and other surgical procedures. The problem is frequently compounded by a failure to recognise the error immediately after surgery when surgical repair has the greatest chance of success. We present cases which outline the risk of accessory nerve injury, the spectrum of clinical presentations and the problems produced by a failure to recognise the deficit. Regional anatomy, consequences of nerve damage and management options are discussed. Diagnostic biopsy of neck nodes should not be undertaken as a primary investigation and, when indicated, surgery in this region should be performed by suitably trained staff under well-defined conditions. Awareness of iatrogenic injury and its consequences would avoid delays in diagnosis and treatment. Images Figure 2 PMID:8678450

  19. Resolving the age of Wilson Creek Formation tephras and the Mono Lake excursion using high-resolution SIMS dating of allanite and zircon rims

    NASA Astrophysics Data System (ADS)

    Vazquez, J. A.; Lidzbarski, M. I.

    2012-12-01

    the recorded event is instead the Laschamp excursion. The results are consistent with a depositional chronology from correlation of relative paleointensity (Zimmerman et al., 2006) that indicates quasi-synchronous glacial and hydrologic responses in the Sierra Nevada and Mono Basin to climate change, with intervals of lake filling and glacial-snowpack melting that are in phase with peaks in spring insolation. Moreover, the results demonstrate that high-spatial resolution SIMS dating of accessory mineral rims is an alternative and promising approach for resolving the depositional ages of silicic tephras containing minerals that crystallized over protracted intervals or that are plagued by incorporation of xenocrysts and/or antecrysts. References: Lajoie, K., 1968, PhD Dissertation, UC Berkeley; Zimmerman et al., 2006, EPSL 252: 94-106.

  20. A reconnaissance ion-probe of hafnium isotopes in zircons

    SciTech Connect

    Kinny, P.D.; Compston, W.; Williams, I.S. )

    1991-03-01

    A SIMS technique for the isotopic analysis of hafnium in zircons using the SHRIMP ion microprobe has been developed, and a precision of typically 0.5{per thousand} (2{sigma}) achieved in the mean reduced {sup 176}Hf/{sup 177}Hf ratio measured at several spots on a single grain. Unfractionated (chondritic) initial Hf isotopic compositions have been measured on a number of Archaean zircon populations. These include the oldest-known terrestrial minerals, the 4.2 Ga-old Mount Narryer detrital zircons, thereby confirming their antiquity. In contrast, positive initial {epsilon}{sub Hf} (relative to the chondritic model composition) has been found in several post-Archaean zircon populations, reflecting the increasing involvement of isotopically evolved depleted mantle sources in the formation of younger crust. The 570 Ma-old Sri Lankan zircon standard SL7 yielded an exceptionally low initial {epsilon}{sub Hf} of {minus}23, implying a metamorphic origin as a reworked product of ancient crust. SHRIMP U-Pb analyses of zircons from Archaean tonalitic gneiss at Watersmeet, Michigan, yield a precise crystallization age of 3636 {plus minus}6 Ma (2{sigma}), and show that a previously reported correlation between {sup 176}Hf/{sup 177}Hf and U-Pb isotopic discordance in bulk zircon samples (Patchett, 1983) was caused by the addition of radiogenic Hf in discrete overgrowths of new zircon ca. 2.7 Ga ago. The original 3.64 Ga grains show no evidence of distrubance to their original (chondritic) Hf isotopic composition. There is presently no evidence for significant isotopic exchange of Hf between zircon and other minerals in crustal rocks.

  1. The use of the scanning electron microscope in the determination of the mineral composition of Ballachulish slate

    SciTech Connect

    Walsh, Joan A.

    2007-11-15

    Slate is a fine-grained, low-grade metamorphic rock derived from argillaceous sediments or occasionally volcanic ash. Although most slates contain mainly quartz, chlorite and white mica, they vary considerably in their durability, some lasting centuries while others fail after a few years of service. A detailed characterisation of their mineralogy is required for the assessment of performance, and to establish the provenance of a used slate. A combination of methods was used to examine Ballachulish slates; XRD analysis to determine the principal minerals present, XRF analysis to determine the total chemical composition, and scanning electron microscopy to determine the chemical composition of individual minerals. It was found that the white mica in Ballachulish slate is phengite and the chlorite is ripidolite. Feldspar is present as albite and carbonate as ferroan dolomite. Several accessory minerals were also identified, including chloritoid, monzonite and zircon. There was considerable variation in the ratio of the principal minerals, making it impossible to identify used slates by this criterion. Instead, chemical composition of the individual minerals, and possibly key accessory minerals, should be used to determine the provenance of slates.

  2. Li diffusion in zircon

    NASA Astrophysics Data System (ADS)

    Cherniak, D. J.; Watson, E. B.

    2010-09-01

    Diffusion of Li under anhydrous conditions at 1 atm and under fluid-present elevated pressure (1.0-1.2 GPa) conditions has been measured in natural zircon. The source of diffusant for 1-atm experiments was ground natural spodumene, which was sealed under vacuum in silica glass capsules with polished slabs of zircon. An experiment using a Dy-bearing source was also conducted to evaluate possible rate-limiting effects on Li diffusion of slow-diffusing REE+3 that might provide charge balance. Diffusion experiments performed in the presence of H2O-CO2 fluid were run in a piston-cylinder apparatus, using a source consisting of a powdered mixture of spodumene, quartz and zircon with oxalic acid added to produce H2O-CO2 fluid. Nuclear reaction analysis (NRA) with the resonant nuclear reaction 7Li(p,γ)8Be was used to measure diffusion profiles for the experiments. The following Arrhenius parameters were obtained for Li diffusion normal to the c-axis over the temperature range 703-1.151°C at 1 atm for experiments run with the spodumene source: D_{text{Li}} = 7.17 × 10^{ - 7} { exp }( - 275 ± 11 {text{kJmol}}^{ - 1} /{text{RT}}){text{m}}2 {text{s}}^{ - 1}. Diffusivities are similar for transport parallel to the c-axis, indicating little anisotropy for Li diffusion in zircon. Similar Li diffusivities were also found for experiments run under fluid-present conditions and for the experiment run with the Dy-bearing source. Li diffusion is considerably faster than diffusion of other cations in zircon, with a smaller activation energy for diffusion. Although Li diffusion in zircon is comparatively rapid, zircons will be moderately retentive of Li signatures at mid-crustal metamorphic temperatures, but they are unlikely to retain this information for geologically significant times under high-grade metamorphism.

  3. A petrographic study of shocked minerals from the Vredefort Dome, South Africa

    NASA Astrophysics Data System (ADS)

    Quintero, R. R.; Cavosie, A. J.

    2007-12-01

    The effects of impact-induced shock metamorphism can be preserved in the microstructure of individual mineral grains in target rocks, and thus provide a record of past impact events. This undergraduate research project is a petrographic study of shock metamorphism preserved in minerals from the Vredefort Dome impact structure, South Africa, with the goal of documenting shock features using standard petrographic techniques. The Vredefort Dome is widely regarded as the oldest and largest preserved impact crater on Earth at 2.02 Ga (Kamo et al., 1996 EPSL), and is thus important in studies of impact processes on the Precambrian Earth. Five samples representing three rock types were collected from the Vredefort Dome: two different quartzites were sampled from the collar zone, including Dominion Group quartzite (Ro) on R53 north of Parys, and quartzite Rjo1 on the maps of Bisschoff (1999). In addition, three granitoids were sampled, including two pseudotachylite breccias, from the center of the dome. Two pseudotachylite samples from quarries within the amphibolite zone contain granitoid clasts; a third sample of granulite-facies granitoid (charnockite) was collected from the amphibolite-granulate transition near Vredefort. In general, all of the samples are quartz-rich, and exhibit quartz grains with variably developed planar deformation features (PDFs). Two and three compelling sets of PDFs within individual grains were only observed in quartz from the collar zone; most samples contain quartz with only one set of conspicuous PDFs, usually decorated, that are readily visible with optical light microscopy. Shock microstructures were also observed in accessory minerals, including zircon. Detrital zircons in quartzite (unit Ro) contain PDFs that are readily apparent with a 10x to 40x objective. The zircons are average size (e.g. 125 microns), and contain parallel PDFs with an apparent regular spacing of 5 microns. Zircons were observed in all granitoid and pseudotachylite

  4. Complete zircon and chromite digestion by sintering of granite, rhyolite, andesite and harzburgite rock reference materials for geochronological purposes

    NASA Astrophysics Data System (ADS)

    Bokhari, Syed Nadeem H.; Meisel, Thomas

    2014-05-01

    Zircon (ZrSiO4) is a common accessory mineral in nature that occurs in a wide variety of sedimentary, igneous, and metamorphic rocks. Zircon has the ability to retain substantial chemical and isotopic information that are used in range of geochemical and geo- chronological investigations. Sample digestion of such rock types is a limiting factor due to the chemical inertness of zircon (ZrSiO4) tourmaline, chromite, barite, monazite, sphene, xenotime etc. as the accuracy of results relies mainly on recovery of analytes from these minerals. Dissolution by wet acid digestions are often incomplete and high blank and total dissolved solids (TDS) contents with alkali fusions lead to an underestimation of analyte concentrations. Hence an effective analytical procedure, that successfully dissolves refractory minerals such as zircon is needed to be employed for reliable analytical results. Na2O2 digestion [1] was applied in characterisation of granite (G-3), rhyolite (MRH), andesite (MGL-AND) and harzburgite (MUH-1) powdered reference material with solution based ICP-MS analysis. In this study we undertake a systematic evaluation of decomposition time and sample:Na2O2 ratio and test portion size after minimising effect of all other constraints that makes homogeneity ambiguous. In recovering zircon and chromite 100 mg test portion was mixed with different amounts of Na2O2 i.e. 100-600 mg. Impact of decomposition time was observed by systematically increasing heating time from 30-45 minutes to 90-120 minutes at 480°C. Different test portion sizes 100-500 mg of samples were digested to control variance of inhomogeneity. An improved recovery of zirconium in zircon in granite (G-3), rhyolite MRH), andesite (MGL-AND) and chromite in harzburgite (MUH-1) was obtained by increasing heating time (2h) at 480°C and by keeping (1:6) ratio of sample:Na2O2. Through this work it has been established that due to presence of zircon and chromite, decomposition time and sample:Na2O2 ratio has

  5. Timing of metasomatism in a subcontinental mantle: evidence from zircon at Finero (Italy)

    NASA Astrophysics Data System (ADS)

    Badanina, I. Yu.; Malitch, K. N.

    2012-04-01

    The Finero phlogopite-peridotite represents a metasomatized residual mantle harzburgite, exposed at the base of the lower-crust section in the Ivrea Zone, Western Alps (Hartmann and Wedepohl 1993). It forms the core of a concentrically zoned sequence of internal layered gabbro, amphibole-rich peridotite and external gabbro. The phlogopite peridotite contains small-size chromitite bodies, with a suite of accessory minerals such as phlogopite, apatite, Ca-Mg carbonates, zirconolite, zircon, thorianite and uraninite, proposed to form during alkaline-carbonatitic metasomatism process within the mantle (Zaccarini et al. 2004). In this study, the combined application of a non-destructive technique to separate zircon from their host rocks (see details at http://www.natires.com) and in-situ analytical technique for compositional and isotopic analysis (SHRIMP-II at Russian Geological Research Institute, St. Petersburg) has provided new more detailed age constraints on the formation of chromitite and related metasomatic events within a mantle tectonite at Finero. Chromitite samples derived from the dump in the prospecting trenches of Rio Creves. In thin sections, zircon occurs as relatively large (up to 200 μm) grains characterized by subhedral to euhedral shapes. Separated grains of zircon form two distinct populations. Dominant zircon population is pale pink and characterized by different shapes (subhedral, subrounded or elongated). In cathodoluminescense, the main set of population is represented by complex grains, which show development of core-rim relationship (most likely recrystallized rim on a preserved core). Subordinate zircon grains are colourless. They are characterized by a smoky cathodoluminescense, with almost no internal pattern. Three main U-Pb age clusters have been recognized. The youngest age cluster, typical for subordinate colourless zircon population and rims in complex grains of dominant pale pink population, show two concordant 206Pb/238U ages (e

  6. Rhabdovirus accessory genes.

    PubMed

    Walker, Peter J; Dietzgen, Ralf G; Joubert, D Albert; Blasdell, Kim R

    2011-12-01

    The Rhabdoviridae is one of the most ecologically diverse families of RNA viruses with members infecting a wide range of organisms including placental mammals, marsupials, birds, reptiles, fish, insects and plants. The availability of complete nucleotide sequences for an increasing number of rhabdoviruses has revealed that their ecological diversity is reflected in the diversity and complexity of their genomes. The five canonical rhabdovirus structural protein genes (N, P, M, G and L) that are shared by all rhabdoviruses are overprinted, overlapped and interspersed with a multitude of novel and diverse accessory genes. Although not essential for replication in cell culture, several of these genes have been shown to have roles associated with pathogenesis and apoptosis in animals, and cell-to-cell movement in plants. Others appear to be secreted or have the characteristics of membrane-anchored glycoproteins or viroporins. However, most encode proteins of unknown function that are unrelated to any other known proteins. Understanding the roles of these accessory genes and the strategies by which rhabdoviruses use them to engage, divert and re-direct cellular processes will not only present opportunities to develop new anti-viral therapies but may also reveal aspects of cellar function that have broader significance in biology, agriculture and medicine.

  7. U-Pb-Th geochronology of monazite and zircon in albitite metasomatites of the Rožňava-Nadabula ore field (Western Carpathians, Slovakia): implications for the origin of hydrothermal polymetallic siderite veins

    NASA Astrophysics Data System (ADS)

    Hurai, V.; Paquette, J.-L.; Lexa, O.; Konečný, P.; Dianiška, I.

    2015-10-01

    Sodic metasomatites (albitites) occur around and within siderite veins in the southern part of the Gemeric tectonic unit of the Western Carpathians. Accessory minerals of the metasomatites represented by monazite, zircon, apatite, rutile, tourmaline and siderite are basically identical with the quartz-tourmaline stage of other siderite and stibnite veins of the tectonic unit. Statistical analysis of chemical Th-U(total)-Pb isochron method (CHIME) of monazite dating yielded Jurassic-Cretaceous ages subdivided into 3-4 modes, spreading over time interval between 78 and 185 Ma. In contrast, LA-ICPMS 206Pb/238U dating carried out on the same monazite grains revealed a narrow crystallization interval, showing ages of Th-poor cores with phengite inclusions identical within the error limit with Th-rich rims with cauliflower-like structure. The determined lower intercept at 139 ± 1 Ma overlapped the Vallanginian-Berriasian boundary, thus corroborating the model of formation of hydrothermal vein structures within an arcuate deformation front built up in the Variscan basement as a response to Early Cretaceous compression, folding and thrusting. In contrast, associated zircons are considerably older than the surrounding Early-Palaeozoic volcano-sedimentary rocks, showing Neoproterozoic ages. The zircon grains in albitite metasomatites are thus interpreted as fragments of Pan-African magmatic detritus incorporated in the vein structures by buoyant hydrothermal fluids.

  8. Prediction of thermodynamic property of Pu-zircon and Pu-pyrochlore

    NASA Astrophysics Data System (ADS)

    Xu, Hulfang; Wang, Yifeng

    2000-07-01

    Due to its high durability, zircon is often present as a heavy mineral in natural environments and is the oldest mineral that has been dated on the earth. There are four zircon structure phases of M4+SiO4 occurring in nature: zircon (ZrSiO4), hafnon (HfSiO4), thorite (ThSiO4), and coffinite (USiO4). These phases may form solid solution. Recent interest in zircon minerals stems from the study of highly durable radioactive waste forms. Crystalline phases of M4+SiO4 with zircon structure have been proposed as a durable ceramic waste form for immobilizing actinides such as Pu, Np, and U. To predict the behavior of zircon-based waste forms in a geologic repository environment as well as to optimize the fabrication of those waste forms, the thermodynamic and kinetic properties for zircon mineral phases have to be determined. In this paper, we use a linear free energy relationship to predict the Gibbs free energies of formation of Pu-bearing phases (Xu et al., 1999). The calculated results show that the PuSiO4 phase with zircon structure is unstable with respect to oxides of PuO2 and quartz. However, the PuSiO4 phase will be stable with respect to oxides of PuO2 and silica glass at low temperature.

  9. Sulfide mineralization associated with arc magmatism in the Qilian Block, western China: zircon U-Pb age and Sr-Nd-Os-S isotope constraints from the Yulonggou and Yaqu gabbroic intrusions

    NASA Astrophysics Data System (ADS)

    Zhang, Zhao-Wei; Li, Wen-Yuan; Gao, Yong-Bao; Li, Chusi; Ripley, Edward M.; Kamo, Sandra

    2014-02-01

    The sulfide-bearing Yulonggou and Yaqu mafic intrusions are located in the southern margin of the Qilian Block, Qinghai Province, western China. They are small dike-like bodies mainly composed of gabbros and diorites. Disseminated sulfides (pyrrhotite, pentlandite, and chalcopyrite) are present as concordant lenses within the intrusions. Precise CA-ID-TIMS zircon U-Pb dating yields the crystallization ages of 443.39 ± 0.42 and 440.74 ± 0.33 Ma for the Yulonggou and Yaqu intrusions, respectively. Whole rock samples from both intrusions show light rare earth element (REE) enrichments relative to heavy REE and pronounced negative Nb-Ta anomalies relative to Th and La, which are consistent with the products of arc basaltic magmatism. The Yulonggou intrusion has negative ɛ Nd values from -5.7 to -7.7 and elevated (87Sr/86Sr) i ratios from 0.711 to 0.714. In contrast, the Yaqu intrusion has higher ɛ Nd values from -4.1 to +8.4 and lower (87Sr/86Sr) i ratios from 0.705 to 0.710. The δ34S values of sulfide separates from the Yulonggou and Yaqu deposits vary from 0.8 to 2.4 ‰ and from 2 to 4.3 ‰, respectively. The γ Os values of sulfide separates from the Yulonggou and Yaqu deposits vary between 80 and 123 and between 963 and 1,191, respectively. Higher γ Os values coupled with higher δ34S values for the Yaqu deposit relative to the Yulonggou deposit indicate that external sulfur played a bigger role in sulfide mineralization in the Yaqu intrusion than in the Yulonggou intrusion. Mixing calculations using Sr-Nd isotope data show that contamination with siliceous crustal materials is more pronounced in the Yulonggou intrusion (up to 20 wt%) than in the Yaqu intrusion (<15 wt%). The distribution of sulfides in both intrusions is consistent with multiple emplacements of sulfide-saturated magmas from depth. The Yulonggou and Yaqu sulfide deposits are not economically valuable under current market condition due to small sizes and low Ni grades, which can be explained

  10. Distinguishing primary and secondary inclusion assemblages in Jack Hills zircons

    NASA Astrophysics Data System (ADS)

    Bell, Elizabeth A.; Boehnke, Patrick; Hopkins-Wielicki, Michelle D.; Harrison, T. Mark

    2015-10-01

    Detrital igneous zircons from Jack Hills, Western Australia, range in age from ~ 3.0 to nearly 4.4 Ga and contain an inclusion assemblage dominated by quartz and muscovite, cited as evidence of their derivation from peraluminous granitoids. However, some phosphate inclusions in these zircons are known to be secondary from their post-depositional U-Pb ages and manifest mineralization along cracks. We undertook a survey of mineral inclusions in 4.3-3.0 Ga Jack Hills zircons with particular emphasis on their relationship to possible alteration features (e.g., cracks, disturbed internal zonation, and visual turbidity). Mineral inclusions revealed at polished surfaces show variations in modal mineralogy, mostly corresponding to their relationship with cracks. Muscovite is common both on and away from cracks, although the chemistry of muscovite inclusions shows little relationship with other potential alteration features. Inclusions filling cracks (secondary) and inclusions isolated from cracks differ in their modal mineralogy, although both suites are rich in muscovite and quartz. The higher incidence of crack-intersecting inclusions among younger zircons may reflect effects of the (generally larger) inclusion size among younger zircons. Mismatches between the isolated and crack-intersecting populations indicate selective loss of certain phases (e.g., feldspar, apatite) and over-representation of quartz and muscovite along cracks likely due to the effects of larger inclusion size and varying degrees of overpressure following zircon cooling and decompression. Inclusions not associated with cracks in magmatically zoned versus regions with disturbed zoning have similar phase proportions. This indicates only minor inclusion replacement away from cracks (i.e., the isolated assemblage is likely primary). This holds true also for inclusions within visually turbid versus clear volumes of zircon. Phase proportions within the inclusion assemblages differ with age indicating a

  11. Petrography and U-Pb Zircon Geochronology of Geological Units of the Mesa de Cocodite, Península de Paraguaná, Venezuela

    NASA Astrophysics Data System (ADS)

    Mendi, D.; Baquero, M. L.; Oliveira, E. P.; Urbani, F.; Pinto, J.; Grande, S.; Valencia, V.

    2013-05-01

    Several continental crust units crop out in The Mesa de Cocodite, central Paraguaná Peninsula, Northwestern Venezuela, including a newly mapped quartz-feldspar gneiss that intruded the El Amparo Pluton, a major low-graded metamorphic unit of Permian age. It is unconformably overlying by Late Jurassic phyllites of the Pueblo Nuevo Formation. All these units are cross-cut by narrow dykes. This contribution focuses on the petrography and LA-ICP-MS U-Pb zircon dating of the igneous units, with the aim of constraining magmatism and its tectonic significance in the area. The quartz-feldspar gneiss consists of albite, bluish-smoked quartz, muscovite-chlorite, epidote and zircon. The enclosing El Amparo Pluton is typically a coarse-grained and thick-banded metagranodiorite, containing andesine, quartz, hornblende, epidote, K-feldspar, biotite, chlorite, titanite and zircon. The younger dykes consist of fine-grained, porphyritic hornblende diorites that contain numerous hornblende phenocrysts. The main minerals are andesine, hornblende, quartz, and chlorite. Accessory minerals include zircon, epidote and opaques. A felsic gneiss xenolith collected from the dykes contain quartz, K-feldspar, chlorite, epidote, albite and zircon. Zircon population in the quartz-feldspar gneiss displays a discordia trend, ranging in age from 1050-750 Ma but mostly around 950-900 Ma, which may represent a peak high-grade metamorphism in the area. The El Amparo Pluton provides a concordant Permian age (271.3±6.5 Ma), which is comparable with previous reported U-Pb ages in titanite. Because the porphyry dykes cross-cut all the units in the area, they should be post-Late Jurassic in Age; however, all dated zircons from the dykes are in the range of 1200-750 Ma. The absence of younger ages can be attributed to either formation during a relatively low temperature magmatic event, which generated very narrow younger zircon rims only and thus undetectable with the technique used, or a completely lack

  12. Paragneiss zircon geochronology and trace element geochemistry, North Qaidam HP/UHP terrane, western China

    USGS Publications Warehouse

    Mattinson, C.G.; Wooden, J.L.; Zhang, J.X.; Bird, D.K.

    2009-01-01

    In the southeastern part of the North Qaidam terrane, near Dulan, paragneiss hosts minor peridotite and UHP eclogite. Zircon geochronology and trace element geochemistry of three paragneiss samples (located within a ???3 km transect) indicates that eclogite-facies metamorphism resulted in variable degrees of zircon growth and recrystallization in the three samples. Inherited zircon core age groups at 1.8 and 2.5 Ga suggest that the protoliths of these rocks may have received sediments from the Yangtze or North China cratons. Mineral inclusions, depletion in HREE, and absence of negative Eu anomalies indicate that zircon U-Pb ages of 431 ?? 5 Ma and 426 ?? 4 Ma reflect eclogite-facies zircon growth in two of the samples. Ti-in-zircon thermometry results are tightly grouped at ???660 and ???600 ??C, respectively. Inclusions of metamorphic minerals, scarcity of inherited cores, and lack of isotopic or trace element inheritance demonstrate that significant new metamorphic zircon growth must have occurred. In contrast, zircon in the third sample is dominated by inherited grains, and rims show isotopic and trace element inheritance, suggesting solid-state recrystallization of detrital zircon with only minor new growth. ?? 2009 Elsevier Ltd.

  13. Accessories or necessities? Exploring consensus on usage of stoma accessories.

    PubMed

    Rudoni, Caroline; Dennis, Heather

    Usage and opinion of accessory products in stoma care vary enormously. The aim of this study was to identify what constitutes an accessory product and to find out whether there is any standardization regarding their recommendation. Views of both patients and stoma nurses were examined. Patients identify accessory products as being necessary both physically and psychologically in improving their quality of life. While stoma nurses identify that the psychological effects of having a stoma should never be underestimated, there is still concern regarding the cost of recommending these products and their clinical necessity. It would appear that clinical necessity is based on nurses' opinions and is not always evidence or research based. Since accessory products have been shown to be essential to many patients with a stoma, should stoma nurses be more empathetic when considering their recommendation?

  14. Interpreting U-Pb data from primary and secondary features in lunar zircon

    NASA Astrophysics Data System (ADS)

    Grange, M. L.; Pidgeon, R. T.; Nemchin, A. A.; Timms, N. E.; Meyer, C.

    2013-01-01

    In this paper, we describe primary and secondary microstructures and textural characteristics found in lunar zircon and discuss the relationships between these features and the zircon U-Pb isotopic systems and the significance of these features for understanding lunar processes. Lunar zircons can be classified according to: (i) textural relationships between zircon and surrounding minerals in the host breccias, (ii) the internal microstructures of the zircon grains as identified by optical microscopy, cathodoluminescence (CL) imaging and electron backscattered diffraction (EBSD) mapping and (iii) results of in situ ion microprobe analyses of the Th-U-Pb isotopic systems. Primary zircon can occur as part of a cogenetic mineral assemblage (lithic clast) or as an individual mineral clast and is unzoned, or has sector and/or oscillatory zoning. The age of primary zircon is obtained when multiple ion microprobe analyses across the polished surface of the grain give reproducible and essentially concordant data. A secondary set of microstructures, superimposed on primary zircon, include localised recrystallised domains, localised amorphous domains, crystal-plastic deformation, planar deformation features and fractures, and are associated with impact processes. The first two secondary microstructures often yield internally consistent and close to concordant U-Pb ages that we interpret as dating impact events. Others secondary microstructures such as planar deformation features, crystal-plastic deformation and micro-fractures can provide channels for Pb diffusion and result in partial resetting of the U-Pb isotopic systems.

  15. Ti Diffusion in Zircon

    NASA Astrophysics Data System (ADS)

    Cherniak, D. J.; Watson, E. B.

    2006-12-01

    Diffusion of Ti under anhydrous conditions at 1 atmosphere and under fluid-present conditions at 1.1-1.2 GPa has been measured in natural zircon. The source of diffusant for 1-atm experiments was a ZrO2- TiO2-ZrSiO4 mixture, with experiments run in Pt capsules. Diffusion experiments conducted in the presence of H2O-CO2 fluid were run in a piston-cylinder apparatus, using a source of ground TiO2, ZrSiO4 and SiO2, with oxalic acid added to produce H2O-CO2 vapor and partially melt the solid source material, yielding an assemblage of rutile + zircon + melt + vapor. Resonant nuclear reaction analysis (NRA) with the nuclear reaction ^{48}Ti(p,Γ)^{49}V was used to measure diffusion profiles for both sets of experiments. The following Arrhenius relation was obtained for Ti diffusion normal to c over the temperature range 1350-1550C at one atmosphere: DTi = 3.3x102 exp(-754 ± 56 kJ mol-1 /RT) m2sec-1 Ti diffusivities were found to be similar for experiments run under fluid-present conditions. A fit to all of the data yields the Arrhenius relation D = 1.3x103 exp(-741 ± 46 kJ mol-1 /RT) m2sec-1. These data suggest that zircon should be extremely retentive of Ti chemical signatures, indicating that the recently developed Ti-in-zircon crystallization geothermometer (Watson and Harrison, 2005; Watson et al., 2006) will be quite robust in preserving temperatures of zircon crystallization. Titanium diffuses somewhat faster in zircon than larger tetravalent cations U, Th, and Hf, but considerably more slowly than Pb, the REE, and oxygen; hence Ti crystallization temperatures may be retained under circumstances when radiometric ages or other types of geochemical information are lost. Watson EB, Harrison TM (2005) Science 308, 841-844. Watson EB, Wark DA, Thomas JB (2006) CMP(in press).

  16. Detrital shocked minerals: microstructural provenance indicators of impact craters

    NASA Astrophysics Data System (ADS)

    Cavosie, A. J.

    2014-12-01

    The study of detrital shocked minerals (DSMs) merges planetary science, sedimentology, mineralogy/crystallography, accessory mineral geochemistry, and geochronology, with the goal of identifying and determining provenance of shock metamorphosed sand grains. Diagnostic high-pressure impact-generated microstructures (planar fractures, planar deformation features) are readily identified on external grain surfaces using standard SEM imaging methods (BSE), and when found, unambiguously confirm an impact origin for a given sand grain. DSMs, including quartz, zircon, monazite, and apatite, have thus far been documented at the Vredefort Dome [1,2,3], Sudbury [4], Rock Elm [5], and Santa Fe [6,7] impact structures. DSMs have been identified in alluvium, colluvium, beach sand, and glacial deposits. Two main processes are recognized that imply the global siliciclastic record contains DSMs: they survive extreme distal transport, and they survive 'deep time' lithification. Distal transport: In South Africa, shocked minerals are preserved in alluvium from the Vaal River >750 km downstream from the Vredefort impact; SHRIMP U-Pb geochronology has confirmed the origin of detrital shocked zircon and monazite from shocked Vredefort bedrock [2]. Vredefort-derived shocked zircons have also been found at the mouth of the Orange River on the Atlantic coast, having travelled ~2000 km downriver from Vredefort [8]. Deep time preservation: Vredefort-derived shocked zircon and quartz has been documented in glacial diamictite from the 300 Myr-old Dwyka Group in South Africa. Shocked minerals were thus entrained and transported in Paleozoic ice sheets that passed over Vredefort [9]. An impact crater can thus be viewed as a unique 'point source', in some cases for billions of years [2,4]; DSMs thus have applications in studying eroded impact craters, sedimentary provenance, landscape evolution, and long-term sediment transport processes throughout the geologic record. This work was supported by

  17. The Use and Abuse of Th-U Ratios in the Interpretation of Zircon

    NASA Astrophysics Data System (ADS)

    Möller, A.; ÓBrien, P. J.; Kennedy, A.; Kröner, A.

    2003-04-01

    In the interpretation of geochronological data the distinction between magmatic and metamorphic zircon is mainly based on morphology, internal zoning or Th-U ratio. This distinction is of doubtful benefit in partially molten high grade metamorphic rocks where partial melting and zircon growth or dissolution may have occurred in several phases. It is proposed that instead of classifying zircon into magmatic and metamorphic groups, differences and changes in chemistry from inherited core to overgrowth can be attributed to growth or recrystallization mechanisms. Taking the distinction literally, only zircon grown by solid state (metamorphic) reactions may be called metamorphic, whereas zircon crystallized from melt is magmatic, and zircon crystallized from fluids is hydrothermal. Trace element characteristics together with the criteria mentioned above may help to link zircon growth to these environments or to other processes altering existing zircon (i.e. metamictisation, annealing, recrystallization, dissolution-reprecipitation). In-situ ion microprobe analysis has been used to track Th-U ratios of zircon through time in polymetamorphic rocks. Several different trends can be distinguished and attributed to different growth mechanisms when combined with cathodo-luminescence and backscatter electron imaging. Unchanged Th/U through time is interpreted to reflect closed system behaviour, lower Th/U in overgrowths can indicate competition for Th with high Th minerals (monazite, allanite etc.), higher Th/U is also observed and interpreted to reflect open system behaviour, breakdown of minerals with high Th/U, or competition with high U minerals (e.g. xenotime). In summary, zircon grown during metamorphic events may not be characterized by low Th/U, and classifying zircon as "metamorphic" solely based on its Th/U as occasionally seen in the literature can lead to gross misinterpretations.

  18. 14 CFR 33.25 - Accessory attachments.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Accessory attachments. 33.25 Section 33.25... STANDARDS: AIRCRAFT ENGINES Design and Construction; General § 33.25 Accessory attachments. The engine must operate properly with the accessory drive and mounting attachments loaded. Each engine accessory drive...

  19. Lead zirconate titanate ceramics

    SciTech Connect

    Walker, B.E. Jr.

    1986-12-02

    This patent describes a lead zirconate titanate (PZT) piezoelectric ceramic composition which, based on total composition weight, consists essentially of a solid solution of lead zirconate and lead titanate in a PbZrO/sub 3/:PbTiO/sub 3/ ratio from about 0.505:0.495 to about 0.54:0.46; a halide salt selected from the group consisting of fluorides and chlorides of alkali metal and alkaline earth elements and mixtures thereof except for francium and radium in an amount from about 0.5 to 2 weight percent; and an oxide selected from the group consisting of magnesium, barium, scandium, aluminum, lanthanum, praesodynium, neodymium, samarium, and mixtures thereof in an amount from about 0.5 to about 6 weight percent, the relative amount of oxide being from about 1 to about 4 times that of the halide.

  20. Mechanisms of radon loss from zircon: Microstructural controls on emanation and diffusion

    NASA Astrophysics Data System (ADS)

    Eakin, Marty; Brownlee, S. J.; Baskaran, M.; Barbero, L.

    2016-07-01

    Understanding how radon escapes from minerals is important for many fields in Earth science, yet few studies have focused on the mechanisms for radon escape. We measured radon emanation rate and radon loss upon heating for crushed aliquots of three large zircon crystals from three localities: Mud Tank (Australia), Bancroft (Canada), and Malawi (Africa). Our study, in conjunction with published data, shows that the room temperature radon emanation coefficient (REC) varies over 5 orders of magnitude in zircon. For low U zircon, Mud Tank, there are variations in REC that appear to be related to annealing at different temperatures, possibly due to annealing of fission tracks, however, all REC values for Mud Tank zircon are within error of one another. Bancroft and Malawi zircons have higher U content and do not show any systematic relationship of REC to annealing temperature. Results from Mud Tank zircon suggest that partial annealing of fission tracks decreases REC, but when all fission tracks are annealed REC reaches a maximum. REC in zircons with high U content, Bancroft and Malawi, is slightly higher than in zircon with lower U, although results are within error. Results of measurements of radon loss upon heating suggest that radon diffusion is slow, ∼30% of the radon is lost during heating at 975 °C for 48 h. Samples heated a second time yield less fractional radon loss, ∼10%, suggesting that diffusion parameters are changed during heating at temperatures ⩾975 °C, which is likely the result of annealing of radiation damage. Diffusion parameters calculated from the fractional loss experiments reflect diffusion in highly radiation damaged or metamict zircons. Our results indicate that internal microstructures in zircon, such as fission tracks and alpha-radiation damage, influence radon escape for diffusion and recoil mechanisms, and hence if these effects can be further characterized, measurements of 222Rn escape have the potential to be useful for probing

  1. Etching fission tracks in zircons

    USGS Publications Warehouse

    Naeser, C.W.

    1969-01-01

    A new technique has been developed whereby fission tracks can be etched in zircon with a solution of sodium hydroxide at 220??C. Etching time varied between 15 minutes and 5 hours. Colored zircon required less etching time than the colorless varieties.

  2. Automobile accessories: Assessment and improvement

    SciTech Connect

    Jackson, M.

    1995-11-01

    With mandates and regulatory policies to meet both the California Air Resources Board (CARB) and the Partnership for a New Generation of Vehicles (PNGV), designing vehicles of the future will become a difficult task. As we look into the use of electric and hybrid vehicles, reduction of the required power demand by influential automobile components is necessary in order to obtain performance and range goals. Among those automobile components are accessories. Accessories have a profound impact on the range and mileage of future vehicles with limited amounts of energy or without power generating capabilities such as conventional vehicles. Careful assessment of major power consuming accessories helps us focus on those that need improvement and contributes to attainment of mileage and range goals for electric and hybrid vehicles.

  3. Advantages of disposable endoscopic accessories.

    PubMed

    Petersen, B T

    2000-04-01

    Despite the prevailing emphasis on falling reimbursements and cost containment, the use of disposable endoscopic accessories has grown tremendously. They offer simplicity of use, certain sterility, and reduced labor costs in exchange for higher purchase costs per procedure and the burden of waste disposal. Disposable accessories provide greater variety, complexity, and utility. They carry a cost burden that may be acceptable when the devices are difficult to reprocess, when they incorporate features that justify the added cost, or when their unit cost approaches purchase plus reprocessing costs for reusable alternatives, such as for biopsy forceps. Units with small volumes may prefer the ease of disposable accessories independent of relative cost issues, while large high-volume units may need to evaluate cost data more carefully to maintain sustainable practices.

  4. The Role of Accessory Phases in the Sm-Nd Isotope Systematics of the Acasta Gneiss Complex

    NASA Astrophysics Data System (ADS)

    Bauer, A.; Fisher, C. M.; Vervoort, J. D.; Bowring, S. A.

    2015-12-01

    The Acasta Gneiss Complex (AGC) of the Slave Craton in the Northwest Territories, Canada, contains some of Earth's oldest continental crust. It is characterized by a range of compositionally diverse gneisses with crystallization ages of 3.3 to > 4.0 Ga1-5. The AGC has undergone a multistage history of metamorphism and deformation. Given these post-crystallization processes, the extent of Nd isotope heterogeneity suggested by published4-7 whole rock Sm-Nd analyses of these rocks has been called into question. Criticisms include the likelihood of mixed lithologies at the hand-sample scale and the potential for open-system behavior of the Sm-Nd isotopic system in these rocks. We obtained whole rock compositional, Sm-Nd and Lu-Hf isotope data paired with Hf in zircon and Nd in titanite and apatite data to further evaluate the isotope record, and use U-Pb and Lu-Hf of zircon as a basis for identifying mixed or complex samples. Preferential preservation of Lu-Hf over Sm-Nd isotope systematics in multiply deformed, complex rocks may be controlled by the minerals that dominate the Hf and Nd budgets, with the majority of the Hf effectively sheltered in zircon and the Nd largely hosted in accessory phases such as apatite and titanite. This composite dataset enables us to evaluate the possibility that Hf and Nd isotopic systematics have been decoupled in these samples that have such critical bearing on our understanding of early crust-forming processes. [1]Bowring and Williams (1999). CoMP, 134(1), 3-16. [2]Iizuka, T. et al. (2006) Geology, 34(4), 245-248. [3]Iizuka et al (2007). Precambrian Res, 153(3), 179-208. [4]Bowring et al. 1989. Nature, 340: 222-225. [5]Mojzsis et al. (2014). GCA, 133, 68-96. [6]Bowring and Housh (1995) Science 269, 1535-1540. [7]Moorbath et al (1997) Chem. Geol. 135, 213-231.

  5. Chemical characteristics of zircon from A-type granites and comparison to zircon of S-type granites

    NASA Astrophysics Data System (ADS)

    Breiter, Karel; Lamarão, Claudio Nery; Borges, Régis Munhoz Krás; Dall'Agnol, Roberto

    2014-04-01

    The trace element content in zircons from A-type granites and rhyolites was investigated by using back-scattered electron images and electron microprobe analyses. The studied Proterozoic (Wiborg batholith, Finland and Pará, Amazonas and Goiás states, Brazil) and Variscan (Krušné Hory/Erzgebirge, Czech Republic and Germany) plutons cover a wide range of rocks, from large rapakivi-textured geochemically primitive plutons to small intrusions of F-, Li-, Sn-, Nb-, Ta-, and U-enriched rare-metal granites. While zircon is one of the first crystallized minerals in less fractionated metaluminous and peraluminous granites, it is a late-crystallized phase in peralkaline granites and in evolved granites that may crystallize during the whole process of magma solidification. The early crystals are included in mica, quartz, and feldspar; the late grains are included in fluorite or cryolite or are interstitial. The zircon in hornblende-biotite and biotite granites from the non-mineralized plutons is poor in minor and trace elements; the zircon in moderately fractionated granite varieties is slightly enriched in Hf, Th, U, Y, and HREEs; whereas the zircon in highly fractionated ore-bearing granites may be strongly enriched in Hf (up to 10 wt.% HfO2), Th (up to 10 wt.% ThO2), U (up to 10 wt.% UO2), Y (up to 12 wt.% Y2O3), Sc (up to 3 wt.% Sc2O3), Nb (up to 5 wt.% Nb2O5), Ta (up to 1 wt.% Ta2O5), W (up to 3 wt.% WO3), F (up to 2.5 wt.% F), P (up to 11 wt.% P2O5), and As (up to 1 wt.% As2O5). Metamictized zircons may also be enriched in Bi, Ca, Fe, and Al. The increase in the Hf content coupled with the decrease in the Zr/Hf value in zircon is one of the most reliable indicators of granitic magma evolution. In the zircon of A-type granites, the Zr/Hf value decreases from 41-67 (porphyritic granite) to 16-19 (equigranular granite) in the Kymi stock, Finland, and from 49-52 (biotite granite) to 18-36 (leucogranite) in the Pedra Branca pluton, Brazil. In the in situ strongly

  6. Zircon U-Th-Pb-He double dating of the Merlin kimberlite field, Northern Territory, Australia

    NASA Astrophysics Data System (ADS)

    McInnes, Brent I. A.; Evans, Noreen J.; McDonald, Brad J.; Kinny, Peter D.; Jakimowicz, Janusz

    2009-11-01

    soon as it was produced by radioactive decay; (ii) the grains were heated by deuteric processes to temperatures in excess of 180 °C following emplacement of the kimberlite pipe. The consistently young (U-Th)/He ages of the kimberlite zircon xenocrysts distinguish them from surficial detrital zircon and this geochemical feature could have application in regional diamond exploration where standard kimberlite indicator minerals (e.g., Cr-pyrope, Cr-diopside, picroilmenite, chromite) are prone to destruction by chemical weathering in tropical and sub-tropical climates.

  7. 1.8 Billion Years of Detrital Zircon Recycling Calibrates a Refractory Part of Earth's Sedimentary Cycle.

    PubMed

    Hadlari, Thomas; Swindles, Graeme T; Galloway, Jennifer M; Bell, Kimberley M; Sulphur, Kyle C; Heaman, Larry M; Beranek, Luke P; Fallas, Karen M

    2015-01-01

    Detrital zircon studies are providing new insights on the evolution of sedimentary basins but the role of sedimentary recycling remains largely undefined. In a broad region of northwestern North America, this contribution traces the pathway of detrital zircon sand grains from Proterozoic sandstones through Phanerozoic strata and argues for multi-stage sedimentary recycling over more than a billion years. As a test of our hypothesis, integrated palynology and detrital zircon provenance provides clear evidence for erosion of Carboniferous strata in the northern Cordillera as a sediment source for Upper Cretaceous strata. Our results help to calibrate Earth's sedimentary cycle by showing that recycling dominates sedimentary provenance for the refractory mineral zircon.

  8. Intrahepatic accessory spleen: imaging features.

    PubMed

    Izzo, Luciano; Caputo, Maria; Galati, Gaspare

    2004-06-01

    The authors present a case report of a 60-year-old man with a hepatic unknown mass. For diagnosis, they used ECO, CT (with and without contrast), MR (with and without contrast) and an ultrasound-assisted percutaneous lesion biopsy. Thus the mass-lesion in the liver appeared to be an intrahepatic accessory spleen in a patient afflicted with chronic hepatitis.

  9. Teaching Techniques for Accessory Percussion

    ERIC Educational Resources Information Center

    Micallef, Ken

    2007-01-01

    Everyone is familiar with the main percussion instruments of the contemporary orchestra: bass drum, snare drum, suspended cymbal, vibraphone, and timpani. But as source material broadens, so do the demands placed on the percussion section. Accessory, or auxiliary percussion, can make the difference between a typical rendition of a well-known piece…

  10. Phosphorus-controlled trace element distribution in zircon revealed by NanoSIMS

    NASA Astrophysics Data System (ADS)

    Yang, Wei; Lin, Yangting; Hao, Jialong; Zhang, Jianchao; Hu, Sen; Ni, Huaiwei

    2016-03-01

    To better understand the origin of oscillatory zoning in zircons, distributions of REEs (represented by Ce, Sm, Dy and Lu), Y, Ti, Li and P in the igneous zircons (QH) from a felsic syenite in the Qinghu alkaline complex and metamorphic zircons (DMP06-14) from a banded granulite xenolith from Hannuoba basalts have been investigated with NanoSIMS. The NanoSIMS analyses reveal well correlation between the trace element distributions and the cathodoluminescence dark-bright zonings of zircons. The QH zircons with oscillatory zonings display large trace element variations within single grains by a factor up to 13.5, with Y and P ranging from 574 and 227 ppm in the bright zones to 7754 and 2464 ppm in the dark zones, respectively. By contrast, the DMP06-14 zircons without oscillatory zonings show much smaller trace element variations by a factor of 1.4, with Y ranging from 477 to 636 ppm and P from 331 to 467 ppm. Such large trace element variations in oscillatory zonings cannot be produced by compositional fluctuation in the magma chambers. The correlations between P and Y, REEs (Ce, Sm, Dy and Lu) ( R 2 > 0.97) indicate xenotime substitution in zircons. The oscillatory distribution of P in zircon could be formed by the fluctuation of P in the melt adjacent to the mineral-melt boundary, either because P diffuses slower than Zr in the melt or due to surfacial interaction of melt with crystals. Such a zoned distribution of P in turn controls the substitution types of phosphates in zircon, developing oscillatory distributions of Y and REEs. Our results indicate that apparent partition coefficients of Y and REEs between zircon and melt are controlled by P contents, which may result in the large discrepancy in zircon partitioning data.

  11. «Granulite» zircons of the Lapland granulite belt

    NASA Astrophysics Data System (ADS)

    Kaulina, T.

    2003-04-01

    An age of the main stage of granulite metamorphism, which followed the overthrusting of the Lapland granulite belt (LGB) is estimated at about 1.91-1.95 Ga (Tugarinov, Bibikova, 1980; Bernard-Griffiths et al., 1984; Bibikova et al., 1993; Mitrofanov et al., 1993). This high-grade metamorphism is dated by U-Pb method on short prismatic gem-quality zircons that are typical for granulites and are interpreted as formed under stress and space-shortage conditions of the high pressure. And the common belief is that these zircon ages are dating the peak conditions of a metamorphic P-T path, since zircon has a high closure temperature of its U-Pb system. We studied rocks with different degree of metamorphism from Yavr and Pados rivers district (Kola Peninsula, Russia) located in the connection zone of the Tanaelv belt and LGB. Samples from the Tanaelv belt were taken from: 1) leucocratic garnet-clinopyroxene-amphibole plagiogneiss, chemically corresponds to andesite and formed under amphibolite facies 2) leucocratic biotite-pyroxene plagiogneiss with mineral association of granulite facies. Lapland granulites are represented by sillimanite-garnet-biotite gneiss from khondalite complex and leuco-mesocratic amphibole-pyroxene-plagioschist, belonging to the charnockite complex. Metamorphic zircons in all studied samples are represented practically by crystals of the same image. These are round or isometric (rarely subidiomorphic-prismatic in mafic granulites) large crystals with bright luster and high transparency. They are colorless or weakly colored into yellowish-pinkish tones. Crystals are zoneless but may contain cores, especially zircons from khondalite, 60% of which contain zoned cores. Thus typically “granulitic” zircon, described in many works, is the dominant type both in granulites of the Lapland belt and in amphiboles gneisses of the Tanaelv belt. Zircons are distinguished by low U contents (up to 100 ppm) and high Th/U and Zr/Hf ratios (0.6-0.7 and 42

  12. Extreme lithium isotopic fractionation in three zircon standards (Plešovice, Qinghu and Temora).

    PubMed

    Gao, Yu-Ya; Li, Xian-Hua; Griffin, William L; Tang, Yan-Jie; Pearson, Norman J; Liu, Yu; Chu, Mei-Fei; Li, Qiu-Li; Tang, Guo-Qiang; O'Reilly, Suzanne Y

    2015-01-01

    To understand the behavior of Li in zircon, we have analyzed the abundance and isotopic composition of Li in three zircon standards (Plešovice, Qinghu and Temora) widely used for microbeam analysis of U-Pb ages and O-Hf isotopes. We have mapped Li concentration ([Li]) on large grains, using a Cameca 1280HR Secondary Ion Mass Spectrometer (SIMS). All zircons have a rim 5-20 μm wide in which [Li] is 5 to 20 times higher than in the core. Up to ~20‰ isotopic fractionation is observed on a small scale in the rims of a single zircon grain. The measured δ(7)Li values range from -14.3 to 3.7‰ for Plešovice, -22.8 to 1.4‰ for Qinghu and -4.7 to 16.1‰ for Temora zircon. The [Li] and δ(7)Li are highly variable at the rims, but relatively homogenous in the cores of the grains. From zircon rim to core, [Li] decreases rapidly, while δ(7)Li increases, suggesting that the large isotopic variation of Li in zircons could be caused by diffusion. Our data demonstrate that homogeneous δ(7)Li in the cores of zircon can retain the original isotopic signatures of the magmas, while the bulk analysis of Li isotopes in mineral separates and in bulk-rock samples may produce misleading data. PMID:26594042

  13. Extreme lithium isotopic fractionation in three zircon standards (Plešovice, Qinghu and Temora).

    PubMed

    Gao, Yu-Ya; Li, Xian-Hua; Griffin, William L; Tang, Yan-Jie; Pearson, Norman J; Liu, Yu; Chu, Mei-Fei; Li, Qiu-Li; Tang, Guo-Qiang; O'Reilly, Suzanne Y

    2015-11-23

    To understand the behavior of Li in zircon, we have analyzed the abundance and isotopic composition of Li in three zircon standards (Plešovice, Qinghu and Temora) widely used for microbeam analysis of U-Pb ages and O-Hf isotopes. We have mapped Li concentration ([Li]) on large grains, using a Cameca 1280HR Secondary Ion Mass Spectrometer (SIMS). All zircons have a rim 5-20 μm wide in which [Li] is 5 to 20 times higher than in the core. Up to ~20‰ isotopic fractionation is observed on a small scale in the rims of a single zircon grain. The measured δ(7)Li values range from -14.3 to 3.7‰ for Plešovice, -22.8 to 1.4‰ for Qinghu and -4.7 to 16.1‰ for Temora zircon. The [Li] and δ(7)Li are highly variable at the rims, but relatively homogenous in the cores of the grains. From zircon rim to core, [Li] decreases rapidly, while δ(7)Li increases, suggesting that the large isotopic variation of Li in zircons could be caused by diffusion. Our data demonstrate that homogeneous δ(7)Li in the cores of zircon can retain the original isotopic signatures of the magmas, while the bulk analysis of Li isotopes in mineral separates and in bulk-rock samples may produce misleading data.

  14. Extreme lithium isotopic fractionation in three zircon standards (Plešovice, Qinghu and Temora)

    PubMed Central

    Gao, Yu-Ya; Li, Xian-Hua; Griffin, William L.; Tang, Yan-Jie; Pearson, Norman J.; Liu, Yu; Chu, Mei-Fei; Li, Qiu-Li; Tang, Guo-Qiang; O’Reilly, Suzanne Y.

    2015-01-01

    To understand the behavior of Li in zircon, we have analyzed the abundance and isotopic composition of Li in three zircon standards (Plešovice, Qinghu and Temora) widely used for microbeam analysis of U-Pb ages and O-Hf isotopes. We have mapped Li concentration ([Li]) on large grains, using a Cameca 1280HR Secondary Ion Mass Spectrometer (SIMS). All zircons have a rim 5–20 μm wide in which [Li] is 5 to 20 times higher than in the core. Up to ~20‰ isotopic fractionation is observed on a small scale in the rims of a single zircon grain. The measured δ7Li values range from –14.3 to 3.7‰ for Plešovice, –22.8 to 1.4‰ for Qinghu and –4.7 to 16.1‰ for Temora zircon. The [Li] and δ7Li are highly variable at the rims, but relatively homogenous in the cores of the grains. From zircon rim to core, [Li] decreases rapidly, while δ7Li increases, suggesting that the large isotopic variation of Li in zircons could be caused by diffusion. Our data demonstrate that homogeneous δ7Li in the cores of zircon can retain the original isotopic signatures of the magmas, while the bulk analysis of Li isotopes in mineral separates and in bulk-rock samples may produce misleading data. PMID:26594042

  15. Impact-shocked zircons: Discovery of shock-induced textures reflecting increasing degrees of shock metamorphism

    NASA Technical Reports Server (NTRS)

    Bohor, B. F.; Betterton, W. J.; Krogh, T. E.

    1993-01-01

    Textural effects specifically characteristic of shock metamorphism in zircons from impact environments have not been reported previously. However, planar deformation features (PDF) due to shock metamorphism are well documented in quartz and other mineral grains from these same environments. An etching technique was developed that allows scanning electron microscope (SEM) visualization of PDF and other probable shock-induced textural features, such as granular (polycrystalline) texture, in zircons from a variety of impact shock environments. These textural features in shocked zircons from K/T boundary distal ejecta form a series related to increasing degrees of shock that should correlate with proportionate resetting of the U-Pb isotopic system.

  16. Impact-shocked zircons: discovery of shock-induced textures reflecting increasing degrees of shock metamorphism

    USGS Publications Warehouse

    Bohor, B.F.; Betterton, W.J.; Krogh, T.E.

    1993-01-01

    Textural effects specifically characteristic of shock metamorphism in zircons from impact environments have not been reported previously. However, planar deformation features (PDF) due to shock metamorphism are well documented in quartz and other mineral grains from these same environments. An etching technique was developed that allows SEM visualization of PDF and other probable shock-induced textural features, such as granular (polycrystalline) texture, in zircons from a variety of impact shock environments. These textural features in shocked zircons from K/T boundary distal ejecta form a series related to increasing degrees of shock that should correlate with proportionate resetting of the UPb isotopic system. ?? 1993.

  17. Annealing effects on cathodoluminescence of zircon

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Y.; Nishido, H.; Noumi, Y.

    2011-12-01

    U-Pb zircon dating (e. g., SHRIMP) is an important tool to interpret a history of the minerals at a micrometer-scale, where cathodoluminescence (CL) imaging allows us to recognize internal zones and domains with different chemical compositions and structural disorder at high spatial resolution. The CL of zircon is attributed by various types of emission centers, which are extrinsic ones such as REE impurities and intrinsic ones such as structural defects. Metamictization resulted from radiation damage to the lattice by alpha particles from the decay of U and Th mostly causes an effect on the CL features of zircon as a defect center. However, slightly radiation-damaged zircon, which is almost nondetectable by XRD, has not been characterized using CL method. In this study, annealing effects on CL of zircon has been investigated to clarify a recovery process of the damaged lattice at low radiation dose. A single crystal of zircon from Malawi was selected for CL measurements. It contains HfO2: 2.30 w.t %, U: 241 ppm and Th: 177 ppm. Two plate samples perpendicular to c and a axes were prepared for annealing experiments during 12 hours from room temperature to 1400 degree C. Color CL images were captured using a cold-cathode microscope (Luminoscope: Nuclide ELM-3R). CL spectral measurements were conducted using an SEM (JEOL: JSM-5410) combined with a grating monochromator (Oxford: Mono CL2) to measure CL spectra ranging from 300 to 800 nm in 1 nm steps with a temperature controlled stage. The dispersed CL was collected by a photoncounting method using a photomultiplier tube (Hamamatsu: R2228) and converted to digital data. All CL spectra were corrected for the total instrumental response. Spectral analysis reveals an anisotropy of the CL emission bands related to intrinsic defect center in blue region, radiation-induced defect center from 500 to 700 nm, and trivalent Dy impurity center at 480 and 580 nm, but their relative intensities are almost constant. CL on the

  18. Locally vascularized pelvic accessory spleen.

    PubMed

    Iorio, F; Frantellizzi, V; Drudi, Francesco M; Maghella, F; Liberatore, M

    2016-01-01

    Polysplenism and accessory spleen are congenital, usually asymptomatic anomalies. A rare case of polysplenism with ectopic spleen in pelvis of a 67-year-old, Caucasian female is reported here. A transvaginal ultrasound found a soft well-defined homogeneous and vascularized mass in the left pelvis. Patient underwent MRI evaluation and contrast-CT abdominal scan: images with parenchymal aspect, similar to spleen were obtained. Abdominal scintigraphy with 99mTc-albumin nanocolloid was performed and pelvic region was studied with planar scans and SPECT. The results showed the presence of an uptake area of the radiopharmaceutical in the pelvis, while the spleen was normally visualized. These findings confirmed the presence of an accessory spleen with an artery originated from the aorta and a vein that joined with the superior mesenteric vein. To our knowledge, in the literature, there is just only one case of a true ectopic, locally vascularized spleen in the pelvis.

  19. Coupled Uranium-Series and (U-Th)/He Zircon Geochronology of the Emmons Lake Volcanic Center (ELVC): Dating the Record of Voluminous Tephra Production in Quaternary Eastern-Beringia.

    NASA Astrophysics Data System (ADS)

    Burgess, S. D.; Vazquez, J. A.; Grove, M. J.; Coble, M. A.; Hourigan, J. K.; Waythomas, C. F.; Coombs, M. L.; Wallace, K.

    2015-12-01

    Tephrochronology is an invaluable tool used to date, link, and reconstruct paleo-environments, climates, and landscapes. Single tephra layers represent isochronous markers across broad regions, thus accurate and precise temporal constraints on the timing of eruption are critical to their utility. If a U-bearing accessory phase such as zircon is present, U/Pb, U-series, and (U-Th)/He geochronometers may be selectively applied. Application of multiple geochronometers to the same sample corroborates accuracy, can potentially resolve mineral crystallization and volcano eruption dates, and can define an eruption age from inherited crystals, assuming complete thermal resetting of the (U-Th)/He system upon crystal incorporation into magma prior to eruption. The Emmons Lake Volcanic Center is one of the largest Quaternary volcanic systems in the Aleutian volcanic arc, and is characterized by at least two major caldera-forming eruptions. C1 has been dated by 40Ar/39Ar at ~238 ka, and was originally proposed as the source for the Old Crow tephra, the largest and most widespread Quaternary tephra in eastern Beringia, and a critical time horizon for reconstruction of Pleistocene paleo-environment and climate. C2 produced the widespread Dawson tephra, and has been dated indirectly by radiocarbon at ~27 ka. We present in-situ grain-surface ion microprobe (SHRIMP-RG) 238U-230Th and/or U/Pb data on a suite of autocrysitc zircon grains from a C1 sample, the Old Crow, and from the Dawson. On these same zircon crystals, we utilize a noble gas sector mass spectrometer to make sensitive, low blank, single crystal 4He measurements. With these datasets, we investigate the temporal and potential genetic relationship between C1 and Old Crow, and place absolute radiogenic time constraints on the C2 eruption. Coupled 238U-230Th and sector field (U-Th)/He application shows significant promise for generating accurate, precise dates for Quaternary tephra bearing a U-rich accessory mineral phase.

  20. Comparative zircon tephrochronology: correlating the Pliocene Bouse tephra, lower Colorado River trough, California, with the Lawlor Tuff of the Sonoma volcanic field, California

    NASA Astrophysics Data System (ADS)

    Harvey, J. C.

    2013-12-01

    Formation tephra with the Lawlor Tuff, independent of the glass chemistry results. Zircon age spectra from both Bouse ash and potential proximal source candidates have elevated MSWD values attributed to protracted crystallization periods, while the Bouse ash includes confounding older age populations attributed to detrital addition. Juvenile zircon age comparison identifies, but cannot distinguish between, two source candidates, the Lawlor Tuff and the 'Pre-Kilogore' tephra from the Heise volcanic complex (Snake River Plain). U concentration variation overlaps between source candidates but yields moderately distinguishing probability curves. Pre-Kilogre zircon have distinctly lower (2.1 ×1.5‰ vs. 6.9 ×0.5 ‰ ) oxygen isotopic composition than Bouse tephra zircon, and thus can be ruled out as a source. Combining multiple zircon characteristics identifies the Bouse Tephra as a distal deposit of the Lawlor Tuff. This identification exemplifies the discriminatory power of accessory minerals, especially if geochronological probability comparison is augmented by stable isotope and trace element analysis.

  1. An integrated microtextural and chemical approach to zircon geochronology: refining the Archaean history of the Napier Complex, east Antarctica

    NASA Astrophysics Data System (ADS)

    Kelly, Nigel M.; Harley, Simon L.

    2005-03-01

    Integrated textural and chemical characterisation of zircon is used to refine the U-Pb geochronology of the Archaean, ultra-high temperature Napier Complex, east Antarctica. Scanning electron microscope characterisation of zircon and the rare earth element compositions of zircon, garnet and orthopyroxene are integrated to place zircon growth in an assemblage context, thereby providing tighter constraints on the timing of magmatic and metamorphic events. Data indicate that magmatism occurred in the central and northern Napier Complex at ca. 2,990 Ma. A regional, relatively low-pressure metamorphic event occurred at ca. 2,850-2,840 Ma. Mineral REE data from garnet-bearing orthogneiss indicate that ca. 2,490-2,485 Ma U-Pb zircon ages provide an absolute minimum age for the ultrahigh temperature (UHT) foliation preserved in this rock. Internal zircon zoning relationships and estimated zircon-garnet DREE values from paragneiss suggest that an absolute minimum age of ultra-high temperature metamorphism is ca. 2,510 Ma, but that it is more likely to be older than ca. 2,545 Ma. We suggest that the high proportion of published zircon U-Pb data with ages between ca. 2,490-2,450 Ma reflects late, post-peak zircon growth and does not date the timing of peak UHT metamorphism.

  2. Crystallographically controlled crystal-plastic deformation of zircon in shear zones

    NASA Astrophysics Data System (ADS)

    Kovaleva, Elizaveta; Klötzli, Urs

    2014-05-01

    common slip systems, screw dislocations or the development of brittle deformation. In this case the internal deformation is mainly controlled by the host phase microstructural arrangement. Crystal lattice distortions of zircon such as plastic deformation features may facilitate intragranular material transport. Enhanced mobility of trace elements or radiogenic isotopes influences isotopic systems used for geochronology. In-situ microstructural study of plastically deformed accessory zircon grains allows linking different stages of high-grade regional metamorphism and deformation. Understanding of zircon deformation mechanisms and their effects on the distribution of trace elements and isotopic systems is important for deriving the age of deformation events. References: Leroux, H., Reimold, W.U., Koeberl, C., Hornemann, U., Doukhan, J.C., 1999. Experimental shock deformation in zircon: a transmission electron microscopic study. Earth and Planetary Science Letters, 169, 291-301. Reddy, S.M., Timms, N.E., Pantleon, W., Trimby, T., 2007. Quantitative characterization of plastic deformation of zircon and geological implications. Contributions to Mineralogy and Petrology 153, 625-645.

  3. Opening the closed box: lattice diffusion in zircon?

    NASA Astrophysics Data System (ADS)

    Wheeler, J.; MacDonald, J.; Goodenough, K. M.; Crowley, Q.; Harley, S.; Mariani, E.

    2015-12-01

    In principle, any radiogenic parent or daughter element can diffuse through any crystalline lattice. Given improved analytic techniques and mathematical models, geochronology is beginning to take such diffusion into account in a quantitative fashion. Whilst lattice diffusion compromises simple interpretation of radiometric data, it can, when combined with spatially resolved data, provide more detailed insight into thermal histories. In regions that have experienced particularly high temperatures diffusion may become significant in minerals normally thought to be reliably closed. We have modelled Pb diffusion in zircon, building on earlier work on Ar diffusion in micas - the mathematics being basically the same. We are motivated by some challenging isotope data from zircon in the Lewisian Complex of NW Scotland (a TTG region with a long Archaean and Proterozoic history). For example we have grains with old rims and younger cores. Whilst other explanations are possible, we show how lattice diffusion of Pb is plausible, using experimental diffusion data together with estimates of ultra-high temperatures from the region. We have modified a previous model for Ar diffusion ("Diffarg") to include variations in parent isotope concentration, so we can understand the consequences of U zonation within zircon grains during prolonged thermal histories. This is also relevant to asking why Pb has apparently not diffused in zircon from other UHT regions - or has it?

  4. Accessory spleen hypertrophy mimicking colon cancer metastasis.

    PubMed

    Ates, I; Yazici, O; Yazilitas, D; Ozdemir, N; Zengin, N

    2016-09-01

    Accessory spleen is a congenital form of an ectopic splenic tissue. In this report, we present a case of a patient who was followed with the diagnosis of rectal and sigmoid colon cancer and an accessory spleen hypertrophy, which was thought to be colon cancer metastasis in the left hypochondriac region. After colectomy and splenectomy, accessory spleen that mimics cancer metastasis was diffrentially diagnosed using scintigraphy. PMID:27685531

  5. Accessory suprarenal gland: report of a case.

    PubMed

    Kirici, Y; Mas, M R; Saglamkaya, U; Oztas, E; Ozan, H

    2001-06-01

    The suprarenal glands are normally located at the superomedial aspect of the kidneys. Accessory cortical masses are seen in approximately half of the newborn but usually disappear later. Several cases with accessory cortical tissues located near the main suprarenal glands have been reported but their usual locations have been rarely described. Here we report a case with accessory cortical tissue located on the right in the retrocrural space with compression symptoms. Such a lesion may be confused with lymphadenopathy radiologically.

  6. Detrital Zircon Geochronology of Cretaceous and Paleogene Strata Across the South-Central Alaskan Convergent Margin

    USGS Publications Warehouse

    Bradley, Dwight; Haeussler, Peter; O'Sullivan, Paul; Friedman, Rich; Till, Alison; Bradley, Dan; Trop, Jeff

    2009-01-01

    Ages of detrital zircons are reported from ten samples of Lower Cretaceous to Paleogene metasandstones and sandstones from the Chugach Mountains, Talkeetna Mountains, and western Alaska Range of south-central Alaska. Zircon ages are also reported from three igneous clasts from two conglomerates. The results bear on the regional geology, stratigraphy, tectonics, and mineral resource potential of the southern Alaska convergent margin. Chugach Mountains - The first detrital zircon data are reported here from the two main components of the Chugach accretionary complex - the inboard McHugh Complex and the outboard Valdez Group. Detrital zircons from sandstone and two conglomerate clasts of diorite were dated from the McHugh Complex near Anchorage. This now stands as the youngest known part of the McHugh Complex, with an inferred Turonian (Late Cretaceous) depositional age no older than 91-93 Ma. The zircon population has probability density peaks at 93 and 104 Ma and a smattering of Early Cretaceous and Jurassic grains, with nothing older than 191 Ma. The two diorite clasts yielded Jurassic U-Pb zircon ages of 179 and 181 Ma. Together, these findings suggest a Mesozoic arc as primary zircon source, the closest and most likely candidate being the Wrangellia composite terrane. The detrital zircon sample from the Valdez Group contains zircons as young as 69 and 77 Ma, consistent with the previously assigned Maastrichtian to Campanian (Late Cretaceous) depositional age. The zircon population has peaks at 78, 91, 148, and 163 Ma, minor peaks at 129, 177, 330, and 352 Ma, and no concordant zircons older than Devonian. A granite clast from a Valdez Group conglomerate yielded a Triassic U-Pb zircon age of 221 Ma. Like the McHugh Complex, the Valdez Group appears to have been derived almost entirely from Mesozoic arc sources, but a few Precambrian zircons are also present. Talkeetna Mountains - Detrital zircons ages were obtained from southernmost metasedimentary rocks of the

  7. Advanced Accessory Power Supply Topologies

    SciTech Connect

    Marlino, L.D.

    2010-06-15

    This Cooperative Research and Development Agreement (CRADA) began December 8, 2000 and ended September 30, 2009. The total funding provided by the Participant (General Motors Advanced Technology Vehicles [GM]) during the course of the CRADA totaled $1.2M enabling the Contractor (UT-Battelle, LLC [Oak Ridge National Laboratory, a.k.a. ORNL]) to contribute significantly to the joint project. The initial task was to work with GM on the feasibility of developing their conceptual approach of modifying major components of the existing traction inverter/drive to develop low cost, robust, accessory power. Two alternate methods for implementation were suggested by ORNL and both were proven successful through simulations and then extensive testing of prototypes designed and fabricated during the project. This validated the GM overall concept. Moreover, three joint U.S. patents were issued and subsequently licensed by GM. After successfully fulfilling the initial objective, the direction and duration of the CRADA was modified and GM provided funding for two additional tasks. The first new task was to provide the basic development for implementing a cascaded inverter technology into hybrid vehicles (including plug-in hybrid, fuel cell, and electric). The second new task was to continue the basic development for implementing inverter and converter topologies and new technology assessments for hybrid vehicle applications. Additionally, this task was to address the use of high temperature components in drive systems. Under this CRADA, ORNL conducted further research based on GM’s idea of using the motor magnetic core and windings to produce bidirectional accessory power supply that is nongalvanically coupled to the terminals of the high voltage dc-link battery of hybrid vehicles. In order not to interfere with the motor’s torque, ORNL suggested to use the zero-sequence, highfrequency harmonics carried by the main fundamental motor current for producing the accessory power

  8. Mechanical accessories for mobile teleoperators

    SciTech Connect

    Feldman, M.J.; Herndon, J.N.

    1985-01-01

    The choice of optimum mechanical accessories for mobile teleoperators involves matching the criteria for emergency response with the available technology. This paper presents a general background to teleoperations, a potpourri of the manipulator systems available, and an argument for force reflecting manipulation. The theme presented is that the accomplishment of humanlike endeavors in hostile environments will be most successful when man model capabilities are utilized. The application of recent electronic technology to manipulator development has made new tools available to be applied to emergency response activities. The development activities described are products of the Consolidated Fuel Reprocessing Program at the Oak Ridge National Laboratory. 13 refs., 7 figs.

  9. Thermal Forensics of Zircons from the Mesoproterozoic Sudbury Impact Structure (ontario, Canada)

    NASA Astrophysics Data System (ADS)

    Prado, D.; Mojzsis, S. J.

    2010-12-01

    The Sudbury Igneous Complex (SIC) forms the central part of the Mesoproterozoic (ca. 1.85 Ga) Sudbury impact structure and comprises three lithological units: norite (bottom), quartz gabbro, and granophyre (top). To determine the precise timing of the impact and the subsequent thermal behavior of the crust to this impact, an experimental approach was formulated to directly assess the associated impact energies by exploiting the crystallo-chemical response of zircon (Zr(SiO4)). The differential (slow) diffusional response of constituent elements (e.g. U, Th, Pb, REEs, Ti) in zircon at different temperatures and time-scales of the thermal pulse associated with impact makes this mineral an ideal recorder of the timing and condition of impact energies. Because titanium concentration in zircon is a function of temperature, we can also use this relationship a useful thermometer to probe time vs. temperature during the impact and its aftermath. Here, we report our studies of individual zircon grains extracted from SIC norite and granophyre drill core samples via standard heavy-mineral techniques (no zircons were found in the quartz gabbro unit). Grains were both hand-picked under an optical microscope and cast in epoxy, or entire heavy-mineral aliquots were cast without bias that arises from hand-picking. Electron imaging was used to identify individual zircons; many of the norite zircons displayed sets of planar deformation features (PDFs) attributable to shock wave deformation from impact, but none of the granophyre zircons displayed such structures. The largest and least altered grains from the sample aliquot we prepared were removed from their mounts and recast in epoxy with standard zircon AS-3 in anticipation of titanium thermometry and uranium-lead geochronology by high-resolution ion microprobe in depth-profile mode. Depth profiling reveals relationships between zircon growth time and the geochemical environment during crystallization and cooling after impact. We

  10. Determination of uranium in zircon

    USGS Publications Warehouse

    Cuttitta, F.; Daniels, G.J.

    1959-01-01

    A routine fluorimetric procedure is described for the determination of trace amounts of uranium in zircon. It employs the direct extraction of uranyl nitrate with ethyl acetate using phosphate as a retainer for zirconium. Submicrogram amounts or uranium are separated in the presence of 100,000 times the amount of zirconium. The modified procedure has been worked out using synthetic mixtures of known composition and zircon. Results of analyses have an accuracy of 97-98% of the contained uranium and a standard deviation of less than 2.5%. ?? 1959.

  11. Th-REE- and Nb-Ta-accessory minerals in post-collisional Ediacaran felsic rocks from the Katerina Ring Complex (S. Sinai, Egypt): An assessment for the fractionation of Y/Nb, Th/Nb, La/Nb and Ce/Pb in highly evolved A-type granites

    NASA Astrophysics Data System (ADS)

    Moreno, J. A.; Molina, J. F.; Bea, F.; Abu Anbar, M.; Montero, P.

    2016-08-01

    The relationships of Y/Nb, Th/Nb, La/Nb and Ce/Pb ratios in A-type felsic rocks from the Ediacaran Katerina Ring Complex, northernmost Arabian-Nubian Shield (ANS; S. Sinai, Egypt), are investigated in this work to understand their behavior during generation of highly evolved granitic magmas and to explore the nature of magma sources. Textural and compositional relationships of cognate Th-REE- and Nb-Ta-accessory minerals in Katerina felsic rocks show that chevkinite-group minerals (CGM), monazite, thorite, allanite and xenotime formed from residual liquids in quartz syenite porphyries, quartz monzonites and peralkaline granites, whereas in aluminous granites, allanite and monazite crystallized early, and thorite and columbite formed from residual liquids. Relationships of Y/Nb, Th/Nb, La/Nb and Ce/Pb ratios with Zr/Hf ratios in the aluminous granites and with Be abundances in the peralkaline granites suggest a decrease in La/Nb and Ce/Pb ratios in the former, and in Y/Nb and La/Nb ratios in the latter with crystallization progress. This contrasts with absence of systematic variations of Th/Nb and Ce/Pb ratios in the peralkaline compositions and of Y/Nb ratio in the aluminous ones. In this latter, Th/Nb ratio can present a significant decrease only in highly evolved compositions. An analysis of Y/Nb, Th/Nb, La/Nb and Ce/Pb relationships in worldwide OIB and subduction-related magmatic suites reveals that A-type felsic rocks with (Th/Nb)N < 1.3, (La/Nb)N < 1.3, and (Ce/Pb)N > 1 may have A1-type affinity, and those with (Th/Nb)N > 2, (La/Nb)N > 2, and (Ce/Pb)N < 1 tend to present A2-type affinity. The crystal fractionation of Th-LREE- and Nb-Ta-accessory minerals and mixing of components derived from the two granite groups may cause deviations from these compositional limits that can be evaluated using constraints imposed by Th/Nb-La/Nb, Ce/Pb-Th/Nb and Ce/Pb-La/Nb relationships in OIB and subduction-related magmatic suites. Three mantle sources might have been

  12. Determination of zircon/melt trace element partition coefficients from SIMS analysis of melt inclusions in zircon

    NASA Astrophysics Data System (ADS)

    Thomas, J. B.; Bodnar, R. J.; Shimizu, N.; Sinha, A. K.

    2002-09-01

    Partition coefficients ( zircon/meltD M) for rare earth elements (REE) (La, Ce, Nd, Sm, Dy, Er and Yb) and other trace elements (Ba, Rb, B, Sr, Ti, Y and Nb) between zircon and melt have been calculated from secondary ion mass spectrometric (SIMS) analyses of zircon/melt inclusion pairs. The melt inclusion-mineral (MIM) technique shows that D REE increase in compatibility with increasing atomic number, similar to results of previous studies. However, D REE determined using the MIM technique are, in general, lower than previously reported values. Calculated D REE indicate that light REE with atomic numbers less than Sm are incompatible in zircon and become more incompatible with decreasing atomic number. This behavior is in contrast to most previously published results which indicate D > 1 and define a flat partitioning pattern for elements from La through Sm. The partition coefficients for the heavy REE determined using the MIM technique are lower than previously published results by factors of ≈15 to 20 but follow a similar trend. These differences are thought to reflect the effects of mineral and/or glass contaminants in samples from earlier studies which employed bulk analysis techniques. D REE determined using the MIM technique agree well with values predicted using the equations of Brice (1975), which are based on the size and elasticity of crystallographic sites. The presence of Ce 4+ in the melt results in elevated D Ce compared to neighboring REE due to the similar valence and size of Ce 4+ and Zr 4+. Predicted zircon/meltD values for Ce 4+ and Ce 3+ indicate that the Ce 4+/Ce 3+ ratios of the melt ranged from about 10 -3 to 10 -2. Partition coefficients for other trace elements determined in this study increase in compatibility in the order Ba < Rb < B < Sr < Ti < Y < Nb, with Ba, Rb, B and Sr showing incompatible behavior (D M < 1.0), and Ti, Y and Nb showing compatible behavior (D M > 1.0). The effect of partition coefficients on melt evolution during

  13. "Fingerprinting" tectono-magmatic provenance using trace elements in igneous zircon

    NASA Astrophysics Data System (ADS)

    Grimes, C. B.; Wooden, J. L.; Cheadle, M. J.; John, B. E.

    2015-12-01

    Over 5300 recent SHRIMP-RG analyses of trace elements (TE) in igneous zircon have been compiled and classified based on their original tectono-magmatic setting to empirically evaluate "geochemical fingerprints" unique to those settings. Immobile element geochemical fingerprints used for lavas are applied with the same rational to zircon, including consideration of mineral competition on zircon TE ratios, and new criteria for distinguishing mid-ocean ridge (MOR), magmatic arc, and ocean island (and other plume-influenced) settings are proposed. The elemental ratios in zircon effective for fingerprinting tectono-magmatic provenance are systematically related to lava composition from equivalent settings. Existing discrimination diagrams using zircon U/Yb versus Hf or Y do not distinguish TE-enriched ocean island settings (i.e., Iceland, Hawaii) from magmatic arc settings. However, bivariate diagrams with combined cation ratios involving U-Nb-Sc-Yb-Gd-Ce provide a more complete distinction of zircon from these settings. On diagrams of U/Yb versus Nb/Yb, most MOR, ocean island, and kimberlite zircon define a broad "mantle-zircon array"; arc zircon defines a parallel array offset to higher U/Yb. Distinctly low U/Yb ratios of MOR zircon (typically <0.1) mirror their parental magmas and long-term incompatible element depletion of the MORB mantle. Plume-influenced sources are distinguished from MOR by higher U/Yb, U/Nb, Nb/Yb, and Nb/Sc. For zircon with U/Yb > 0.1, high Sc/Yb separates arc settings from low-Sc/Yb plume-influenced sources. The slope of scandium enrichment trends in zircon differ between MOR and continental arc settings, likely reflecting the involvement of amphibole during melt differentiation. Scandium is thus also critical for discriminating provenance, but its behavior in zircon probably reflects contrasting melt fractionation trends between tholeiitic and calc-alkaline systems more than compositional differences in primitive magmas sourced at each

  14. Lattice distortion in a zircon population and its effects on trace element mobility and U-Th-Pb isotope systematics: examples from the Lewisian Gneiss Complex, northwest Scotland

    NASA Astrophysics Data System (ADS)

    MacDonald, John M.; Wheeler, John; Harley, Simon L.; Mariani, Elisabetta; Goodenough, Kathryn M.; Crowley, Quentin; Tatham, Daniel

    2013-07-01

    Zircon is a key mineral in geochemical and geochronological studies in a range of geological settings as it is mechanically and chemically robust. However, distortion of its crystal lattice can facilitate enhanced diffusion of key elements such as U and Pb. Electron backscatter diffraction (EBSD) analysis of ninety-nine zircons from the Lewisian Gneiss Complex (LGC) of northwest Scotland has revealed five zircons with lattice distortion. The distortion can take the form of gradual bending of the lattice or division of the crystal into subgrains. Zircon lattices are distorted because of either post-crystallisation plastic distortion or growth defects. Three of the five distorted zircons, along with many of the undistorted zircons in the population, were analysed by ion microprobe to measure U and Pb isotopes, Ti and REEs. Comparison of Th/U ratio, 207Pb/206Pb age, REE profile and Ti concentration between zircons with and without lattice distortion suggests that the distortion is variably affecting the concentration of these trace elements and isotopes within single crystals, within samples and between localities. REE patterns vary heterogeneously, sometimes relatively depleted in heavy REEs or lacking a Eu anomaly. Ti-in-zircon thermometry records temperatures that were either low (~700 °C) or high (>900 °C) relative to undistorted zircons. One distorted zircon records apparent 207Pb/206Pb isotopic ages (-3.0 to +0.3 % discordance) in the range of ~2,420-2,450 Ma but this does not correlate with any previously dated tectonothermal event in the LGC. Two other distorted zircons give discordant ages of 2,331 ± 22 and 2,266 ± 40 Ma, defining a discordia lower intercept within error of a late amphibolite-facies tectonothermal event. This illustrates that Pb may be mobilised in distorted zircons at lower metamorphic grade than in undistorted zircons. These differences in trace element abundances and isotope systematics in distorted zircons relative to undistorted

  15. Comparison of Zircon (Ti) Thermometry and Typology of the Cappadocian Ignimbrites

    NASA Astrophysics Data System (ADS)

    Akin, Lutfiye; Aydar, Erkan; Schmitt, Axel K.; Çubukçu, H. Evren

    2014-05-01

    The typological study of zircons is a valuable, convenient, reliable and economical tool since this mineral is highly resistant to alteration and post-magmatic heating. The zircon morphology yields information on temperature and the chemistry of magma hence can be a perfect indicator of the origin of material (e.g., crustal, hybrid or mantle). Zircon typology method has been applied to 8 different ignimbrite successions (Kavak-9.3 Ma, Zelve-9.2 Ma, Sarimadentepe-8.4 Ma, Sofular-8.2 Ma, Cemilkoy-7.2 Ma, Tahar-6.1 Ma, Gordeles-6.4 Ma, Kizilkaya-5.2 Ma) of Miocene-Pliocene in Central Anatolian Volcanic Province. The growth of the pyramidal and prismal faces of zircon crystals, extracted from pumices of each ignimbrite, has been examined and plot onto typology diagram. The temperature index (I.T.), which depends on the relative change of the (110) and (100) prismal faces and alkaline index (I.A.), which depends on the change of the (211) and (301) pyramidal faces, are determined. Typological Evolution Trend (T.E.T) which is used for granitoid classification, is drawn based on estimated I.T. and I.A.. Furthermore, Ti-thermometry of zircons has been applied in order to estimate the emplacement temperatures of the magmatic rocks. For that purpose, Ti concentrations of zircons and host rocks are determined. Zircon evolution temperatures and zircon saturation temperatures are calculated according to Ferry and Watson (2007) and Watson and Harrison (1983). Obtained zircon geothermometry data have been correlated with the zircon typology data. Zircon evolution temperature estimated from zircon crystals are 741oC ( Tmin=-30oC and Tmax=16oC) for Kavak, 749oC (Tmin=-31oC and Tmax=33oC) for Zelve, 811oC (Tmin=-37oC and Tmax=53 oC) for Sarimadentepe, 807oC (Tmin=-24oC and Tmax=61oC) for Sofular, 739oC (Tmin=-58oC and Tmax=42oC) for Cemilkoy, 768oC for Tahar, 806oC (Tmin=-37oC and Tmax=29oC) for Gordeles, 805oC (Tmin=-35oC and Tmax=69oC) for Gordeles-B, 765oC (Tmin=-25oC and Tmax=48

  16. 14 CFR 27.1163 - Powerplant accessories.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... involved; (2) Use the provisions on the engine for mounting; and (3) Be sealed in such a way as to prevent contamination of the engine oil system and the accessory system. (b) Unless other means are provided, torque... drive system to prevent damage to these components from excessive accessory load. Powerplant...

  17. 14 CFR 27.1163 - Powerplant accessories.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... involved; (2) Use the provisions on the engine for mounting; and (3) Be sealed in such a way as to prevent contamination of the engine oil system and the accessory system. (b) Unless other means are provided, torque... drive system to prevent damage to these components from excessive accessory load. Powerplant...

  18. Three Accessories for a Rotating Platform.

    ERIC Educational Resources Information Center

    Riley, James A.; Fryer, Oscar G.

    1980-01-01

    Describes three accessories developed to be used in conjunction with the rotating platform or turntable. Three demonstrations using these accessories are included. These demonstrations are: (a) conservation of angular momentum; (b) gravity-defying goblets; and (c) direct measurement of centripetal force. (HM)

  19. 21 CFR 890.5925 - Traction accessory.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Traction accessory. 890.5925 Section 890.5925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5925 Traction accessory....

  20. 21 CFR 890.5925 - Traction accessory.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Traction accessory. 890.5925 Section 890.5925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5925 Traction accessory....

  1. 21 CFR 890.5925 - Traction accessory.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Traction accessory. 890.5925 Section 890.5925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5925 Traction accessory....

  2. 21 CFR 890.5925 - Traction accessory.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Traction accessory. 890.5925 Section 890.5925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5925 Traction accessory....

  3. 21 CFR 890.5925 - Traction accessory.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Traction accessory. 890.5925 Section 890.5925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5925 Traction accessory....

  4. Selective zircon accumulation in a new benthic foraminifer, Psammophaga zirconia, sp. nov.

    PubMed

    Sabbatini, A; Negri, A; Bartolini, A; Morigi, C; Boudouma, O; Dinelli, E; Florindo, F; Galeazzi, R; Holzmann, M; Lurcock, P C; Massaccesi, L; Pawlowski, J; Rocchi, S

    2016-07-01

    Benthic foraminifera are single-celled eukaryotes that make a protective organic, agglutinated or calcareous test. Some agglutinated, single-chambered taxa, including Psammophaga Arnold, 1982, retain mineral particles in their cytoplasm, but the selective mechanism of accumulation is not clear. Here, we report the ability of a foraminiferal species to select and accumulate zircons and other heavy minerals in their cytoplasm. In particular, the use of Scanning Electron Microscope coupled with an Energy Dispersive X-ray microanalysis system (SEM-EDS) enabled a representative overview of the mineral diversity and showed that the analysed Psammophaga zirconia sp. nov. individuals contained dominantly crystals of zircon (51%), titanium oxides (27%), and ilmenite (11%) along with minor magnetite and other minerals. The studied specimens occur in the shallow central Adriatic Sea where the sediment has a content of zircon below 1% and of other heavy minerals below 4%. For that reason we hypothesize that: (i) P. zirconia may be able to chemically select minerals, specifically zircon and rutile; (ii) the chemical mechanism allowing the selection is based on electrostatic interaction, and it could work also for agglutinated foraminifera (whether for ingestion, like Xenophyophores, or incorporation in the test as in many other described taxa). In particular, this aptitude for high preferential uptake and differential ingestion or retention of zircon is reported here for the first time, together with the selection of other heavy minerals already described in members of the genus Psammophaga. They are generally counted among early foraminifera, constructing a morphologically simple test with a single chamber. Our molecular phylogenetic study confirms that P. zirconia is a new species, genetically distinctive from other Psammophaga, and occurs in the Adriatic as well as in the Black Sea.

  5. Selective zircon accumulation in a new benthic foraminifer, Psammophaga zirconia, sp. nov.

    PubMed

    Sabbatini, A; Negri, A; Bartolini, A; Morigi, C; Boudouma, O; Dinelli, E; Florindo, F; Galeazzi, R; Holzmann, M; Lurcock, P C; Massaccesi, L; Pawlowski, J; Rocchi, S

    2016-07-01

    Benthic foraminifera are single-celled eukaryotes that make a protective organic, agglutinated or calcareous test. Some agglutinated, single-chambered taxa, including Psammophaga Arnold, 1982, retain mineral particles in their cytoplasm, but the selective mechanism of accumulation is not clear. Here, we report the ability of a foraminiferal species to select and accumulate zircons and other heavy minerals in their cytoplasm. In particular, the use of Scanning Electron Microscope coupled with an Energy Dispersive X-ray microanalysis system (SEM-EDS) enabled a representative overview of the mineral diversity and showed that the analysed Psammophaga zirconia sp. nov. individuals contained dominantly crystals of zircon (51%), titanium oxides (27%), and ilmenite (11%) along with minor magnetite and other minerals. The studied specimens occur in the shallow central Adriatic Sea where the sediment has a content of zircon below 1% and of other heavy minerals below 4%. For that reason we hypothesize that: (i) P. zirconia may be able to chemically select minerals, specifically zircon and rutile; (ii) the chemical mechanism allowing the selection is based on electrostatic interaction, and it could work also for agglutinated foraminifera (whether for ingestion, like Xenophyophores, or incorporation in the test as in many other described taxa). In particular, this aptitude for high preferential uptake and differential ingestion or retention of zircon is reported here for the first time, together with the selection of other heavy minerals already described in members of the genus Psammophaga. They are generally counted among early foraminifera, constructing a morphologically simple test with a single chamber. Our molecular phylogenetic study confirms that P. zirconia is a new species, genetically distinctive from other Psammophaga, and occurs in the Adriatic as well as in the Black Sea. PMID:27001345

  6. Mesozoic magmatism and timing of epigenetic Pb-Zn-Ag mineralization in the western Fortymile mining district, east-central Alaska: Zircon U-Pb geochronology, whole-rock geochemistry, and Pb isotopes

    USGS Publications Warehouse

    Dusel-Bacon, Cynthia; Aleinkoff, J.N.; Day, W.C.; Mortensen, J.K.

    2015-01-01

    Epigenetic Pb-Zn-Ag ± Cu prospects in the western Fortymile district are spatially associated with splays of the northeast-trending Kechumstuk sinistral-normal fault zone and with ca. 68-66 Ma felsic intrusions and dikes. The similarity between Pb isotope compositions of feldspars from the Late Cretaceous igneous bodies and sulfides from the epithermal prospects suggests a Late Cretaceous age for most of the mineralization. Fluid flow along the faults undoubtedly played a major role in mineralization. We interpret displacement on the northeast-trending faults to be a far-field effect of dextral translation along Late Cretaceous plate-scale boundaries and faults that were roughly parallel to the subsequently developed Denali and Tintina fault systems, which currently bound the region.

  7. Amplifying Earth history: Zircon U-Pb geochronology by ID-TIMS at the 0.1 ‰ level using new 1013 ohm resistors

    NASA Astrophysics Data System (ADS)

    Wotzlaw, Jörn-Frederik; von Quadt, Albrecht

    2016-04-01

    Precise and accurate radiometric dating of volcanic ash beds in sedimentary successions is the backbone of the numerical calibration of Earth history. Uranium-lead geochronology by isotope dilution thermal ionization mass spectrometry (ID-TIMS) is the most precise and accurate dating technique and is applicable to most of Earth history from the Hadean to the Pleistocene. The accessory mineral zircon is the prime target material due to its commonly high U concentration, virtually no initial Pb and high daughter-product retentivity. However, complex crystallization histories as well as magmatic and sedimentary recycling of zircons require the analysis of single crystals resulting in small amounts of radiogenic Pb (Pb* usually <100 pg) available for mass spectrometry. Precise and accurate isotope ratio determinations on such small samples require highly sensitive ion detection systems making ion counting detectors such as secondary electron multipliers and Daly photomultipliers the most commonly employed detectors for the analysis of small Pb* ion beams. While these detector systems are highly sensitive they are limited by their restricted linear dynamic range and require dynamic peak hopping to collect multiple isotopes. We recently demonstrated the applicability of new 1013 ohm resistors in the Faraday cup amplifier feedback loop for the static multi-collection of all tracer and sample Pb isotopes with 202,205,206,207,208Pb measured on Faraday cups and 204Pb measured in the axial SEM of a Thermo Scientific TRITON Plus TIMS instrument [1]. These measurements take advantage of the superior stability of Faraday detectors, their significantly larger dynamic range and the multiple advantages of static multi collector analyses (longer counting on peak, simultaneous collection of all isotopes etc.). Here, we document recent advances in our analytical protocols that further improve the precision, accuracy and reproducibility of U and Pb isotope ratio measurements of small

  8. Carcinoma in accessory axillary breast.

    PubMed

    Khanna, Seema; Mishra, Shashi Prakash; Kumar, Satendra; Khanna, Ajay Kumar

    2015-08-10

    We present a rare case of carcinoma developing in an accessory breast. The patient presented with a progressive lump in her right axilla for 1 year. On examination, there was a well-developed nipple areola complex in the right axilla overlying a hard, fixed 5 × 3 cm lump. On investigation, core biopsy revealed poorly differentiated carcinoma of the breast. Mammography also revealed features of a malignant lesion with skin and muscle infiltration. Neoadjuvant chemotherapy was administered followed by modified radical mastectomy after three cycles. Immunohistochemistry study showed positive status of oestrogen and progesterone receptors, and negative HER-2 neu. Three more cycles of chemotherapy along with 50 Gy radiotherapy were given in an adjuvant setting followed by hormone therapy.

  9. 19 CFR 10.920 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 19 Customs Duties 1 2012-04-01 2012-04-01 false Accessories, spare parts, or tools. 10.920 Section... Promotion Agreement Rules of Origin § 10.920 Accessories, spare parts, or tools. (a) General. Accessories... accessories, spare parts, or tools will be treated as originating goods if the good is an originating...

  10. 19 CFR 10.456 - Accessories, spare parts or tools.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... good will be treated as a material used in the production of the good, if— (a) The accessories, spare... 19 Customs Duties 1 2014-04-01 2014-04-01 false Accessories, spare parts or tools. 10.456 Section... Trade Agreement Rules of Origin § 10.456 Accessories, spare parts or tools. Accessories, spare parts...

  11. 19 CFR 10.920 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 1 2013-04-01 2013-04-01 false Accessories, spare parts, or tools. 10.920 Section... Promotion Agreement Rules of Origin § 10.920 Accessories, spare parts, or tools. (a) General. Accessories... accessories, spare parts, or tools will be treated as originating goods if the good is an originating...

  12. 19 CFR 10.456 - Accessories, spare parts or tools.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... good will be treated as a material used in the production of the good, if— (a) The accessories, spare... 19 Customs Duties 1 2011-04-01 2011-04-01 false Accessories, spare parts or tools. 10.456 Section... Trade Agreement Rules of Origin § 10.456 Accessories, spare parts or tools. Accessories, spare parts...

  13. 19 CFR 10.456 - Accessories, spare parts or tools.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... good will be treated as a material used in the production of the good, if— (a) The accessories, spare... 19 Customs Duties 1 2012-04-01 2012-04-01 false Accessories, spare parts or tools. 10.456 Section... Trade Agreement Rules of Origin § 10.456 Accessories, spare parts or tools. Accessories, spare parts...

  14. 19 CFR 10.456 - Accessories, spare parts or tools.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... good will be treated as a material used in the production of the good, if— (a) The accessories, spare... 19 Customs Duties 1 2013-04-01 2013-04-01 false Accessories, spare parts or tools. 10.456 Section... Trade Agreement Rules of Origin § 10.456 Accessories, spare parts or tools. Accessories, spare parts...

  15. 19 CFR 10.456 - Accessories, spare parts or tools.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... good will be treated as a material used in the production of the good, if— (a) The accessories, spare... 19 Customs Duties 1 2010-04-01 2010-04-01 false Accessories, spare parts or tools. 10.456 Section... Trade Agreement Rules of Origin § 10.456 Accessories, spare parts or tools. Accessories, spare parts...

  16. 19 CFR 10.920 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 1 2014-04-01 2014-04-01 false Accessories, spare parts, or tools. 10.920 Section... Promotion Agreement Rules of Origin § 10.920 Accessories, spare parts, or tools. (a) General. Accessories... accessories, spare parts, or tools will be treated as originating goods if the good is an originating...

  17. 14 CFR 29.1163 - Powerplant accessories.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... continued rotation of an engine-driven cabin supercharger or any remote accessory driven by the engine will be a hazard if they malfunction, there must be means to prevent their hazardous rotation...

  18. 14 CFR 23.1163 - Powerplant accessories.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... in the event it malfunctions. (d) If the continued rotation of any accessory remotely driven by the engine is hazardous when malfunctioning occurs, a means to prevent rotation without interfering with...

  19. 14 CFR 29.1163 - Powerplant accessories.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... continued rotation of an engine-driven cabin supercharger or any remote accessory driven by the engine will be a hazard if they malfunction, there must be means to prevent their hazardous rotation...

  20. 14 CFR 23.1163 - Powerplant accessories.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... in the event it malfunctions. (d) If the continued rotation of any accessory remotely driven by the engine is hazardous when malfunctioning occurs, a means to prevent rotation without interfering with...

  1. 14 CFR 23.1163 - Powerplant accessories.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... in the event it malfunctions. (d) If the continued rotation of any accessory remotely driven by the engine is hazardous when malfunctioning occurs, a means to prevent rotation without interfering with...

  2. 14 CFR 23.1163 - Powerplant accessories.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... in the event it malfunctions. (d) If the continued rotation of any accessory remotely driven by the engine is hazardous when malfunctioning occurs, a means to prevent rotation without interfering with...

  3. 14 CFR 23.1163 - Powerplant accessories.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... in the event it malfunctions. (d) If the continued rotation of any accessory remotely driven by the engine is hazardous when malfunctioning occurs, a means to prevent rotation without interfering with...

  4. 14 CFR 29.1163 - Powerplant accessories.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... continued rotation of an engine-driven cabin supercharger or any remote accessory driven by the engine will be a hazard if they malfunction, there must be means to prevent their hazardous rotation...

  5. 46 CFR 169.671 - Accessories.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Electrical Electrical Installations Operating at Potentials of Less Than 50 Volts on Vessels of Less Than 100 Gross Tons § 169.671 Accessories. Each light, receptacle and switch exposed to the weather must...

  6. The Accessory Genome of Pseudomonas aeruginosa

    PubMed Central

    Kung, Vanderlene L.; Ozer, Egon A.; Hauser, Alan R.

    2010-01-01

    Summary: Pseudomonas aeruginosa strains exhibit significant variability in pathogenicity and ecological flexibility. Such interstrain differences reflect the dynamic nature of the P. aeruginosa genome, which is composed of a relatively invariable “core genome” and a highly variable “accessory genome.” Here we review the major classes of genetic elements comprising the P. aeruginosa accessory genome and highlight emerging themes in the acquisition and functional importance of these elements. Although the precise phenotypes endowed by the majority of the P. aeruginosa accessory genome have yet to be determined, rapid progress is being made, and a clearer understanding of the role of the P. aeruginosa accessory genome in ecology and infection is emerging. PMID:21119020

  7. Trace element chemistry of zircons from oceanic crust: A method for distinguishing detrital zircon provenance

    USGS Publications Warehouse

    Grimes, Craig B.; John, Barbara E.; Kelemen, P.B.; Mazdab, F.K.; Wooden, J.L.; Cheadle, Michael J.; Hanghoj, K.; Schwartz, J.J.

    2007-01-01

    We present newly acquired trace element compositions for more than 300 zircon grains in 36 gabbros formed at the slow-spreading Mid-Atlantic and Southwest Indian Ridges. Rare earth element patterns for zircon from modern oceanic crust completely overlap with those for zircon crystallized in continental granitoids. However, plots of U versus Yb and U/Yb versus Hf or Y discriminate zircons crystallized in oceanic crust from continental zircon, and provide a relatively robust method for distinguishing zircons from these environments. Approximately 80% of the modern ocean crust zircons are distinct from the field defined by more than 1700 continental zircons from Archean and Phanerozoic samples. These discrimination diagrams provide a new tool for fingerprinting ocean crust zircons derived from reservoirs like that of modern mid-ocean ridge basalt (MORB) in both modern and ancient detrital zircon populations. Hadean detrital zircons previously reported from the Acasta Gneiss, Canada, and the Narryer Gneiss terrane, Western Australia, plot in the continental granitoid field, supporting hypotheses that at least some Hadean detrital zircons crystallized in continental crust forming magmas and not from a reservoir like modern MORB. ?? 2007 The Geological Society of America.

  8. The geological microprobe: The first 25 years of dating zircons

    NASA Astrophysics Data System (ADS)

    Compston, W.; Clement, S. W. J.

    2006-07-01

    Andersen and Hinthorne reported in situ Pb isotope ages for lunar minerals in the early 1970s. ‘Peak stripping’ was used to subtract isobaric interferences but it worked only for old, U-rich targets. Jim Long entered the race for in situ mineral dating using high resolution to separate isobars. Despite low sensitivity, he achieved 207Pb/206Pb dating of zircons in the late 1970s. In 1980 we finished the large instrument SHRIMP I based on the magnetic analyser design of Matsuda that delivered both high resolution and high sensitivity. A year later we found zircon grains 4200 million years old, far older than any previous terrestrial age. Certain in situ isotope studies remained inaccessible, such as Sr isotopes in Ca-rich minerals. All need 20,000 R with high sensitivity to accumulate enough counts for worthwhile precision. In 1990, Matsuda published new reverse-geometry designs that have still higher resolution, one of which we completed in 1997. We achieved 20,000 R but so far only at reduced sensitivity. Its full potential will be realised after further testing including computer simulations.

  9. Uranium and minor-element partitioning in Fe-Ti oxides and zircon from partially melted granodiorite, Crater Lake, Oregon

    SciTech Connect

    La Tourrette, T.Z.; Burnett, D.S. ); Bacon C.R. )

    1991-02-01

    Crystal-liquid partitioning in Fe-Ti oxides and zircon was studied in partially melted granodiorite blocks ejected during the climactic eruption of Mt. Mazama (Crater Lake), Oregon. The blocks, which contain up to 33% rhyolite glass (75 wt% SiO{sub 2}), are interpreted to be portions of the magma chamber walls that were torn off during eruption. The glass is clear and well homogenized for all measured elements except Zr. Results for Fe-Ti oxides give D{sub U}{sup oxide/liq} {approx} 0.1. Partitioning of Mg, Mn, Al, Si, V, and Cr in Fe-Ti oxides indicates that grains surrounded by glass are modestly well equilibrated with the melt for many of the minor elements, while those that are inclusions in relict plagioclase are not. Uranium and ytterbium inhomogeneities in zircons indicate that the zircons have only partially equilibrated with the melt and that uranium appears to have been diffusing out of the zircons have only partially equilibrated with the melt and that uranium appears to have been diffusing out of the zircons faster that the zircons were dissolving. Based on the authors measurements and given their low abundances in most rocks, Fe-Ti oxides probably do not play a major role in U-Th fractional during partial melting. The partial melts were undersaturated with zircon and apatite, but both phases are present in the authors samples. This demonstrates an actual case of nonequilibrium source retention of accessory phases, which in general could be an important trace element fractionation mechanism. Their results do not support the hypothesis that liquid structure is the dominant factor controlling trace-element partitioning in high-silica rhyolites.

  10. Uranium and minor-element partitioning in Fe-Ti oxides and zircon from partially melted granodiorite, Crater Lake, Oregon

    USGS Publications Warehouse

    Tourrette, T.Z.L.; Burnett, D.S.; Bacon, C.R.

    1991-01-01

    Crystal-liquid partitioning in Fe-Ti oxides and zircon was studied in partially melted granodiorite blocks ejected during the climactic eruption of Mt. Mazama (Crater Lake), Oregon. The blocks, which contain up to 33% rhyolite glass (75 wt% SiO2), are interpreted to be portions of the magma chamber walls that were torn off during eruption. The glass is clear and well homogenized for all measured elements except Zr. Results for Fe-Ti oxides give DUoxide/liq ??? 0.1. Partitioning of Mg, Mn, Al, Si, V, and Cr in Fe-Ti oxides indicates that grains surrounded by glass are moderately well equilibrated with the melt for many of the minor elements, while those that are inclusions in relict plagioclase are not. Uranium and ytterbium inhomogeneities in zircons indicate that the zircons have only partially equilibrated with the melt and that uranium appears to have been diffusing out of the zircons faster than the zircons were dissolving. Minimum U, Y, and P concentrations in zircons give maximum DUzrc/liq = 13,DYzrc/liq = 23, and DPzrc/liq = 1, but these are considerably lower than reported by other workers for U and Y. Based on our measurements and given their low abundances in most rocks, Fe-Ti oxides probably do not play a major role in U-Th fractionation during partial melting. The partial melts were undersaturated with zircon and apatite, but both phases are present in our samples. This demonstrates an actual case of non-equilibrium source retention of accessory phases, which in general could be an important trace-element fractionation mechanism. Our results do not support the hypothesis that liquid structure is the dominant factor controlling trace-element partitioning in high-silica rhyolites. Rough calculations based on Zr gradients in the glass indicate that the samples could have been partially molten for 800 to 8000 years. ?? 1991.

  11. Radiation damage effects in zircon

    NASA Astrophysics Data System (ADS)

    Trachenko, Kostya; Dove, Martin; Salje, Ekhard

    2002-03-01

    Zircon, ZrSiO_4, is important for geology and geochronology, and has been proposed as a host material to immobilize highly radioactive materials from dismantled weapons and nuclear waste from power stations [1]. In these applications zircon is exposed to alpha-irradiation. Computer simulations have started to be employed to simulate radiation damage in zircon [2], but the origin and microscopic mechanisms of the most important structural changes in zircon - unit cell expansion and large macroscopic swelling at higher doses, strong shear deformation of the crystalline lattice, and polymerization of SiOn units [3], remain unknown. Here, we perform the molecular dynamics simulation of highly energetic recoils in zircon. Basing on the simulation results, we propose the simple picture of the density change in the damaged region that consists of the depleted and densified matter. We find that the experimentally observed structural changes originate from the interaction of the damaged region with the surrounding crystalline lattice: the shear of the lattice around the damaged region causes shear deformation and expansion of the unit cells. The polymers of connected SiOn polyhedra are most commonly present in the densified shell at the periphery of the damaged region. [1] R C Ewing et al, J. Mater. Res. 10, 243 (1995); W J Weber et al, B E Burakov et al, in Scientific Basis for Nuclear Waste Management XIX, 25-32 and 33-40 (Plenum, New York, 1996); R C Ewing, et al in Crystalline Ceramics: Waste Forms for the Disposal of Weapons Plutonium, NATO Workshop Proceedings 65 (Academic Publishers, Dordrecht, The Netherlands, 1996). [2] B Park et al, Phys. Rev. B, 64, 174108 (1-16) (2001); J P Crocombette and D Ghaleb, J. Nucl. Mater., 295, 167 (2001); K Trachenko et al, J. Appl. Phys., 87, 7702 (2000); K Trachenko et al, J. Phys.: Cond. Matt., 13, 1947 (2001). [3] T Murakami et al, Am. Min., 76, 1510 (1991); H D Holland and D Gottfried, Acta Cryst. 8, 291 (1955).; W J Weber, J. Am

  12. Metallic lead nanospheres discovered in ancient zircons.

    PubMed

    Kusiak, Monika A; Dunkley, Daniel J; Wirth, Richard; Whitehouse, Martin J; Wilde, Simon A; Marquardt, Katharina

    2015-04-21

    Zircon (ZrSiO4) is the most commonly used geochronometer, preserving age and geochemical information through a wide range of geological processes. However, zircon U-Pb geochronology can be affected by redistribution of radiogenic Pb, which is incompatible in the crystal structure. This phenomenon is particularly common in zircon that has experienced ultra-high temperature metamorphism, where ion imaging has revealed submicrometer domains that are sufficiently heterogeneously distributed to severely perturb ages, in some cases yielding apparent Hadean (>4 Ga) ages from younger zircons. Documenting the composition and mineralogy of these Pb-enriched domains is essential for understanding the processes of Pb redistribution in zircon and its effects on geochronology. Using high-resolution scanning transmission electron microscopy, we show that Pb-rich domains previously identified in zircons from East Antarctic granulites are 5-30 nm nanospheres of metallic Pb. They are randomly distributed with respect to zircon crystallinity, and their association with a Ti- and Al-rich silica melt suggests that they represent melt inclusions generated during ultra-high temperature metamorphism. Metallic Pb is exceedingly rare in nature and previously has not been reported in association with high-grade metamorphism. Formation of these metallic nanospheres within annealed zircon effectively halts the loss of radiogenic Pb from zircon. Both the redistribution and phase separation of radiogenic Pb in this manner can compromise the precision and accuracy of U-Pb ages obtained by high spatial resolution methods.

  13. Metallic lead nanospheres discovered in ancient zircons.

    PubMed

    Kusiak, Monika A; Dunkley, Daniel J; Wirth, Richard; Whitehouse, Martin J; Wilde, Simon A; Marquardt, Katharina

    2015-04-21

    Zircon (ZrSiO4) is the most commonly used geochronometer, preserving age and geochemical information through a wide range of geological processes. However, zircon U-Pb geochronology can be affected by redistribution of radiogenic Pb, which is incompatible in the crystal structure. This phenomenon is particularly common in zircon that has experienced ultra-high temperature metamorphism, where ion imaging has revealed submicrometer domains that are sufficiently heterogeneously distributed to severely perturb ages, in some cases yielding apparent Hadean (>4 Ga) ages from younger zircons. Documenting the composition and mineralogy of these Pb-enriched domains is essential for understanding the processes of Pb redistribution in zircon and its effects on geochronology. Using high-resolution scanning transmission electron microscopy, we show that Pb-rich domains previously identified in zircons from East Antarctic granulites are 5-30 nm nanospheres of metallic Pb. They are randomly distributed with respect to zircon crystallinity, and their association with a Ti- and Al-rich silica melt suggests that they represent melt inclusions generated during ultra-high temperature metamorphism. Metallic Pb is exceedingly rare in nature and previously has not been reported in association with high-grade metamorphism. Formation of these metallic nanospheres within annealed zircon effectively halts the loss of radiogenic Pb from zircon. Both the redistribution and phase separation of radiogenic Pb in this manner can compromise the precision and accuracy of U-Pb ages obtained by high spatial resolution methods. PMID:25848043

  14. Metallic lead nanospheres discovered in ancient zircons

    PubMed Central

    Kusiak, Monika A.; Dunkley, Daniel J.; Wirth, Richard; Whitehouse, Martin J.; Wilde, Simon A.; Marquardt, Katharina

    2015-01-01

    Zircon (ZrSiO4) is the most commonly used geochronometer, preserving age and geochemical information through a wide range of geological processes. However, zircon U–Pb geochronology can be affected by redistribution of radiogenic Pb, which is incompatible in the crystal structure. This phenomenon is particularly common in zircon that has experienced ultra-high temperature metamorphism, where ion imaging has revealed submicrometer domains that are sufficiently heterogeneously distributed to severely perturb ages, in some cases yielding apparent Hadean (>4 Ga) ages from younger zircons. Documenting the composition and mineralogy of these Pb-enriched domains is essential for understanding the processes of Pb redistribution in zircon and its effects on geochronology. Using high-resolution scanning transmission electron microscopy, we show that Pb-rich domains previously identified in zircons from East Antarctic granulites are 5–30 nm nanospheres of metallic Pb. They are randomly distributed with respect to zircon crystallinity, and their association with a Ti- and Al-rich silica melt suggests that they represent melt inclusions generated during ultra-high temperature metamorphism. Metallic Pb is exceedingly rare in nature and previously has not been reported in association with high-grade metamorphism. Formation of these metallic nanospheres within annealed zircon effectively halts the loss of radiogenic Pb from zircon. Both the redistribution and phase separation of radiogenic Pb in this manner can compromise the precision and accuracy of U–Pb ages obtained by high spatial resolution methods. PMID:25848043

  15. High-spatial-resolution isotope geochemistry of monazite (U-Pb & Sm-Nd) and zircon (U-Pb & Lu-Hf) in the Old Woman and North Piute Mountains, Mojave Desert, California

    NASA Astrophysics Data System (ADS)

    Phillips, Stacy E.; Hanchar, John M.; Miller, Calvin F.; Fisher, Christopher M.; Lancaster, Penny J.; Darling, James R.

    2014-05-01

    Recent improvements in analytical capabilities allow us to reveal details of magmatic processes at an increasingly finer spatial and temporal scale. In situ analyses of the isotopic and trace element composition of accessory minerals at the sub-grain scale have proven to be effective tools for solving a wide range of geological problems. This study presents new data on accessory minerals including monazite & zircon, examined by in situ LA-ICP-MS and Laser Ablation Split Stream (LASS) techniques, analyzing multiple isotopic systems (U-Pb + Sm-Nd, and U-Pb + Lu-Hf in monazite and zircon, respectively) in order to track geochemical changes over time through a magmatic system. The late Cretaceous granitoids of the Old Woman Mountains in the Mojave Desert, California, provide an excellent opportunity to apply these analytical techniques. The peraluminous granites of the Sweetwater Wash, Painted Rock, and North Piute plutons represent different depths of the magmatic system, and are well understood in terms of field relations and whole-rock geochemistry. A preliminary study on the Sweetwater Wash monazites (Fisher et al., in preparation) has revealed significant inter-grain isotopic heterogeneity in the ɛNd composition of the source region (~1700 Ma); however, the U-Pb ages show an isotopic resetting during emplacement at ~75 Ma. This decoupling of U-Pb and Sm-Nd isotopic systems is suggested by Fisher et al. to be due to recrystallisation and/or dissolution-reprecipitation of monazite. If grain boundary diffusion of Pb overrides the more kinetically limited volume diffusion, then the U-Pb systematics will be reset while Sm and Nd remain immobile in the monazite structure as essential structural components of the lattice. This new data will allow the further investigation of these preliminary results, providing new insights into the observed isotopic disequilibrium, with the LASS technique accurately linking the multiple isotopic systems. This will provide important

  16. Li zoning in zircon as a potential geospeedometer and peak temperature indicator

    NASA Astrophysics Data System (ADS)

    Trail, Dustin; Cherniak, Daniele J.; Watson, E. Bruce; Harrison, T. Mark; Weiss, Benjamin P.; Szumila, Ian

    2016-03-01

    Zircon Li concentrations and δ7Li values may potentially trace crustal recycling because continental and mantle-derived zircons yield distinct values. The usefulness of these differences may depend upon the retentivity of zircon to Li concentrations and isotopic ratios. Given the relatively high Li diffusivities measured by Cherniak and Watson (Contrib Mineral Petrol 160: 383-390, 2010), we sought to discover the scenarios under which Li mobility might be inhibited by charge-compensating cations. Toward this end, we conducted "in" diffusion experiments in which Li depth profiles of synthetic Lu-doped, P-doped, and undoped zircon were determined by nuclear reaction analysis. In separate experiments, Li was ion-implanted at depth within polished natural zircon slabs to form a Gaussian Li concentration profile. Diffusively relaxed concentration profiles were measured after heating the slabs to determine diffusivities. In all experiments, which ranged from 920 to 650 °C, calculated diffusivities are in agreement with a previously established Arrhenius relationship calibrated on trace-element-poor Mud Tank zircon. Our revised Arrhenius relationship that includes both datasets is: D_{Li} = 9.60 × 10^{ - 7} exp [ {{ - 278 ± 8{{kJ}/{mol}^{ - 1} }}{RT}} ]{m}^{ 2} {{s}}^{ - 1} We also observed that synthetic sector-zoned zircon exhibits near-step-function Li concentration profiles across sectors that correlate with changes in the rare earth element (REE) and P concentrations. This allowed us to examine how Li diffusion might couple with REE diffusion in a manner different than that described above. In particular, re-heating these grains revealed significant Li migration, but no detectable migration of the rare earth elements. Thus, unlike most elements in zircon which are not mobile at the micrometer scale under most time-temperature paths in the crust, Li zoning, relaxation of zoning, or lack of zoning altogether could be used to reveal time-temperature information

  17. The role of detrital zircons in Hadean crustal research

    NASA Astrophysics Data System (ADS)

    Nebel, Oliver; Rapp, Robert P.; Yaxley, Gregory M.

    2014-03-01

    Meso-Archean sedimentary sequences at Mt. Narryer and the Jack Hills of the Narryer Terrane in Western Australia's Yilgarn Craton contain detrital zircon grains with ages as old as 4.37 Ga, the oldest preserved terrestrial matter. These grains are rare remnants of Hadean (4.5-4.0 Ga) terrestrial crust and their survival stems from the crystallographic properties of zircon during crustal reworking: they are resistant to physical and chemical weathering. Zircons are further suitable for single grain, precise age determinations making them a unique archive of the crustal past. Only a small proportion of all detrital zircons from the Narryer Terrane show Hadean age spectra and younger overgrowth rims on all 'Hadean' grains indicate multiple recycling events. Numerous studies that applied a spectacular range of analytical tools and proxies have been undertaken to decipher the geochemical nature of these zircons' host rocks, in order to place constraints on Hadean geodynamics and the processes responsible for creating the earliest terrestrial crust. Their elemental and isotope budget and mineral inclusions have helped to develop an emerging picture of a water-rich, evolved Hadean crust. However, subsequent studies have challenged this view and it seems that each piece of new evidence indicative of an early, evolved continental crust has non-unique interpretations also permissive of mafic to ultra-mafic crust. In this review we examine these disparate interpretations and their possible implications and conclude that at least parts of the earliest terrestrial crust were hydrated. However, to date there is no conclusive evidence for preserved granitic, continental crust. The protoliths of the Hadean detrital zircons were likely acidic in nature, yet the composition of the greater terrane from which these melts were derived was probably mafic. It remains unclear if the zircons formed in a geodynamic environment that includes Hadean subduction. We suspect that the Hadean

  18. Laparoscopic excision of infarcted accessory spleen.

    PubMed

    Yousef, Yasmin; Cameron, Brian H; Maizlin, Zeev V; Boutross-Tadross, Odette

    2010-04-01

    An accessory spleen is present in about 10-30% of the population and, usually, does not cause symptoms. We present a case report of an unusual presentation of accessory spleen infarction, with a literature review. A 12-year old male presented with acute left-upper quadrant pain that slowly resolved. An ultrasound and computed tomography scan showed a 3.5 x 2.5 x 2 cm solid mass abutting and displacing the splenic flexure of the colon, with surrounding inflammatory changes. This was interpreted as a colonic duplication cyst, and the boy was treated with antibiotics and underwent elective laparoscopic exploration. It was removed laparoscopically without complication and, on pathologic examination, proved to be consistent with an infarcted accessory spleen. Less than two dozen similar cases of accessory spleen infarction have been reported in the literature, most presenting with acute abdominal pain. Preoperative diagnoses included appendicitis, ovarian torsion, neoplasm, and, in our case, colonic duplication. The natural course of infarcted accessory spleen would be to atrophy, but, even with advanced imaging techniques, it may be impossible to diagnose infarcted accessory spleen with enough confidence to avoid surgery.

  19. Evaluating the Paleomagnetic Potential of Zircons

    NASA Astrophysics Data System (ADS)

    Fu, R. R.; Lima, E. A.; Weiss, B. P.; Glenn, D. R.; Kehayias, P.; Walsworth, R. L.

    2015-12-01

    Because zircon crystals commonly display high natural U/Pb ratios and excellent resistance to weathering, paleomagnetic data collected from zircons potentially enjoy the benefits of excellent age controls and minimal remagnetization from infiltrating fluids. We present rock magnetic and paleomagnetic experiments on two sets of zircons with contrasting geologic histories to determine the viability of zircons as paleomagnetic recorders. First, we characterize primary zircons from the Bishop Tuff, a pyroclastic deposit formed at 767±1 ka in a magnetic field of 43±3 µT. Magnetic field maps with ~10 µm resolution obtained with the nitrogen vacancy (NV) diamond magnetometer indicate that most ferromagnetic sources are situated within zircon interiors, suggesting a primary origin (Fig. 1A). Stepwise thermal demagnetization reveals well-defined components of magnetization blocked in most samples up to 580˚C, indicating the dominance of magnetite, which is the expected primary phase. The intensity of natural remanent magnetization (NRM) is typically 10-12 Am2. Ongoing Thellier-Thellier dual heating experiments will evaluate the accuracy of recovered paleointensities. Second, we study Hadean and Archean detrital zircons from the Jack Hills. In contrast to the Bishop Tuff samples, magnetic microscopy and stepwise thermal demagnetization demonstrate that the remanent magnetization of >80% of Jack Hills zircon are carried exclusively by secondary hematite situated on grain surfaces (Fig. 1B). NRM intensities range between 10-15 and 10-12 Am2 and decrease by a factor of several upon chemical removal of secondary hematite. Our analyses reveal a diversity of ferromagnetic mineralogies and distribution in natural zircons. While some zircon populations carry reliable paleomagnetic information, others are dominated by secondary ferromagnetic phases. Without the application of high-resolution magnetic microscopy techniques to identify the main ferromagnetic carrier, it is

  20. 21 CFR 878.4950 - Manual operating table and accessories and manual operating chair and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Manual operating table and accessories and manual operating chair and accessories. 878.4950 Section 878.4950 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY...

  1. 21 CFR 878.4960 - Operating tables and accessories and operating chairs and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Operating tables and accessories and operating chairs and accessories. 878.4960 Section 878.4960 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES...

  2. 21 CFR 878.4950 - Manual operating table and accessories and manual operating chair and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Manual operating table and accessories and manual operating chair and accessories. 878.4950 Section 878.4950 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY...

  3. 21 CFR 878.4960 - Operating tables and accessories and operating chairs and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Operating tables and accessories and operating chairs and accessories. 878.4960 Section 878.4960 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES...

  4. 21 CFR 878.4950 - Manual operating table and accessories and manual operating chair and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Manual operating table and accessories and manual operating chair and accessories. 878.4950 Section 878.4950 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY...

  5. 21 CFR 878.4960 - Operating tables and accessories and operating chairs and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Operating tables and accessories and operating chairs and accessories. 878.4960 Section 878.4960 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES...

  6. 21 CFR 878.4960 - Operating tables and accessories and operating chairs and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Operating tables and accessories and operating chairs and accessories. 878.4960 Section 878.4960 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES...

  7. 21 CFR 878.4950 - Manual operating table and accessories and manual operating chair and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Manual operating table and accessories and manual operating chair and accessories. 878.4950 Section 878.4950 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY...

  8. 21 CFR 878.4950 - Manual operating table and accessories and manual operating chair and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Manual operating table and accessories and manual operating chair and accessories. 878.4950 Section 878.4950 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY...

  9. 21 CFR 878.4960 - Operating tables and accessories and operating chairs and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Operating tables and accessories and operating chairs and accessories. 878.4960 Section 878.4960 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES...

  10. Cathodoluminescence Microscopy and Spectroscopy of Planar Deformation Features of Shocked Zircon from the Vredefort Impact Structure, South Africa

    SciTech Connect

    Gucsik, A.

    2009-08-17

    Thorough understanding of the shock metamorphic signatures of zircon will provide a basis for the application of this mineral as a powerful tool for the study of terrestrial impact structures and formations. This paper of the cathodoluminescence (CL) spectroscopic signatures of naturally shocked zircon crystals from the Vredefort Dome, South Africa contributes to the understanding of the formation of microdeformation in zircon under very high pressures. All investigated shocked samples shows an inverse relationship between the brightness of the backscattered electron (BSE) signal and the corresponding cathodoluminescence intensity of the zonation patterns. The CL spectra of samples are characterised by narrow emission lines and broad bands in the region of visible light and in the near-ultraviolet range. The emission lines result from rare earth element activators and the broad bands are associated with lattice defects. The results show a clear relationship between the CL properties of zircon and shock pressure, which confirm the possible use of these methods as shock indicators.

  11. 1.8 Billion Years of Detrital Zircon Recycling Calibrates a Refractory Part of Earth’s Sedimentary Cycle

    PubMed Central

    Hadlari, Thomas; Swindles, Graeme T.; Galloway, Jennifer M.; Bell, Kimberley M.; Sulphur, Kyle C.; Heaman, Larry M.; Beranek, Luke P.; Fallas, Karen M.

    2015-01-01

    Detrital zircon studies are providing new insights on the evolution of sedimentary basins but the role of sedimentary recycling remains largely undefined. In a broad region of northwestern North America, this contribution traces the pathway of detrital zircon sand grains from Proterozoic sandstones through Phanerozoic strata and argues for multi-stage sedimentary recycling over more than a billion years. As a test of our hypothesis, integrated palynology and detrital zircon provenance provides clear evidence for erosion of Carboniferous strata in the northern Cordillera as a sediment source for Upper Cretaceous strata. Our results help to calibrate Earth's sedimentary cycle by showing that recycling dominates sedimentary provenance for the refractory mineral zircon. PMID:26658165

  12. Zircon xenocryst resorption and magmatic regrowth at El Chichón Volcano, Chiapas, Mexico

    NASA Astrophysics Data System (ADS)

    Pack, Brenda; Schmitt, Axel K.; Roberge, Julie; Tenorio, Felipe Garcia; Damiata, Brian N.

    2016-02-01

    El Chichón volcano is the only active volcano located within the Chiapanecan Volcanic Arc in southern Mexico, which lies between the Trans-Mexican Volcanic Belt and the Central American Volcanic Arc. Previous studies have shown that ~ 12 eruptions have occurred at El Chichón within the last 8000 years, forming a complex of lava domes with a central crater and surrounding pyroclastic deposits. Here, we report the discovery of zircon in Holocene El Chichón rocks, which were analyzed by high spatial resolution imaging (color cathodoluminescence CCL) and isotopic (secondary ionization mass spectrometry SIMS) methods to resolve core and rim crystallization ages. Pumice samples from five proximal pyroclastic flow and fall-out deposits were collected based on published stratigraphy. Two of the samples were further (re-)classified by new 14C dates. In addition, we sampled two lavas from the 1982 eruption and from remnants of the older Somma lava complex. Zircon crystals were dated using 230Th/238U disequilibrium (U-Th) and U-Pb geochronology. U-Th zircon ages fall between near eruption ages and ca. 84 ka, with overlapping ages in all samples. By contrast, zircon core U-Pb ages range between ca. 290 Ma and 1.9 Ga. These ages are consistent with xenocrystic origins and their heterogeneity indicates derivation from clastic country rocks. Strong age contrasts between inherited xenocrystic and young magmatic domains in individual zircon crystals are evidence for arrested assimilation of crustal rocks where initially zircon-undersaturated magmas cooled rapidly to form a crystal mush or subsolidus amalgamate as a crustally contaminated boundary layer. This layer contributed zircon crystals to eruptible magma during episodic recharge events followed by partial melt extraction, mixing and homogenization. Zircon overgrowths are significantly older than major minerals whose U-series ages and sharp zonation boundaries suggest crystallization only within a few ka before eruption

  13. Recovering the primary geochemistry of Jack Hills zircons through quantitative estimates of chemical alteration

    NASA Astrophysics Data System (ADS)

    Bell, Elizabeth A.; Boehnke, Patrick; Harrison, T. Mark

    2016-10-01

    Despite the robust nature of zircon in most crustal and surface environments, chemical alteration, especially associated with radiation damaged regions, can affect its geochemistry. This consideration is especially important when drawing inferences from the detrital record where the original rock context is missing. Typically, alteration is qualitatively diagnosed through inspection of zircon REE patterns and the style of zoning shown by cathodoluminescence imaging, since fluid-mediated alteration often causes a flat, high LREE pattern. Due to the much lower abundance of LREE in zircon relative both to other crustal materials and to the other REE, disturbance to the LREE pattern is the most likely first sign of disruption to zircon trace element contents. Using a database of 378 (148 new) trace element and 801 (201 new) oxygen isotope measurements on zircons from Jack Hills, Western Australia, we propose a quantitative framework for assessing chemical contamination and exchange with fluids in this population. The Light Rare Earth Element Index is scaled on the relative abundance of light to middle REE, or LREE-I = (Dy/Nd) + (Dy/Sm). LREE-I values vary systematically with other known contaminants (e.g., Fe, P) more faithfully than other suggested proxies for zircon alteration (Sm/La, various absolute concentrations of LREEs) and can be used to distinguish primary compositions when textural evidence for alteration is ambiguous. We find that zircon oxygen isotopes do not vary systematically with placement on or off cracks or with degree of LREE-related chemical alteration, suggesting an essentially primary signature. By omitting zircons affected by LREE-related alteration or contamination by mineral inclusions, we present the best estimate for the primary igneous geochemistry of the Jack Hills zircons. This approach increases the available dataset by allowing for discrimination of on-crack analyses (and analyses with ambiguous or no information on spot placement or

  14. Zircon solubility and of Zr species in subduction zone fluids

    NASA Astrophysics Data System (ADS)

    Wilke, M.; Schmidt, C.; Rickers, K.; Pascarelli, S.; Manning, C. E.; Stechern, A.

    2009-12-01

    The geochemical signature of igneous rocks at convergent plate margins is thought to result from complex melt formation processes involving aqueous solutions derived from dehydration of the subducted slab. In these processes, the depletion of high-field-strength elements (HFSE) may be controlled by the presence of accessory phases such as zircon and rutile, which can strongly fractionate these elements; however, the stability and solubility of these phases depends strongly on the fluid composition, including concentration and stoichiometry of Na-Al silicate components. Here we present new data on the influence of the fluid composition on zircon solubility as well as data on the Zr complexation in these fluids at P&T. Experiments were conducted using a modified hydrothermal diamond-anvil cell (HDAC). Zr contents at P&T were determined using SR-µXRF spectra. Zr K-edge X-ray Absorption Fine Structure (XAFS) spectra were acquired to investigate the Zr complexation in-situ at P&T. A grain of synthetic crystalline zircon was equilibrated with an aqueous fluid containing Na2Si2O5 or Na2Si2O5 + Al2O3 components. XAFS and SR-µXRF spectra were taken at the dispersive beamline ID24 of the ESRF, Grenoble, France. Some additional SR-µXRF spectra were taken at HASYLAB, Hamburg, beamline L. The observed Zr concentrations in fluids containing 7-33 wt% Na2Si2O5 and variable Al contents were between 75 and 720 ppm at 500 to 750°C and ~300 MPa to ~700 MPa. These values match expected solubilities calculated from linear interpolation of the maximum solubility in pure H2O (from the detection limit) and the solubility in the most alkaline high-silica melts reported by Ellison and Hess (1986, CMP, 94, 343). The high Zr solubility in sodium silicate-bearing solutions signifies that aqueous fluids with alkali silicates offer an efficient mechanism for HFSE transport. This can be explained by complexation of HFSE with Si, Na, and perhaps also Al, via formation of polymerized solutes

  15. Radon Emanation from Zircon as a Function of Grain Size, Temperature and Fission Track Density

    NASA Astrophysics Data System (ADS)

    Eakin, M.; Barbero, L.; Brownlee, S. J.; Baskaran, M. M.

    2012-12-01

    Radon emanation from rocks and minerals is ubiquitous. Quantification of radon emanation rates from zircon is critical to assess the reliability of U-Pb ages of zircon bearing rocks. The 238U decay chain includes 222Rn, a noble gas, which can readily escape the crystal structure if sufficient escape pathways in lattice structure exist, ultimately leading to a deficiency of 206Pb in the parent crystal. Few studies have directly investigated the link between track density and 222Rn emanation rates, and none have done this for zircon. In order to evaluate the factors affecting radon emanation from the mineral zircon under different conditions, a series of experiments were performed on a large, crushed Mud Tank zircon crystal. Five different grain sizes (500 μm, 250-500 μm, 125-250 μm, 63 - 125 μm, and < 63 μm) were separated and sealed in closed glass jars and radon emanation rates were measured at 25 C. These aliquots are then subjected to a range of temperatures (100 C, 200 C, 400 C, and 600 C) for six hours and the radon emanation rates are measured after each heating step. Fission track densities are measured after the same annealing temperature steps allowing quantification of 222Rn emanation rate as a function of fission track density. The concentration of 210Pb, 234Th, 212Pb, 226Ra and 228Ra in these fractions are also measured using gamma spectroscopy. The results of these experiments will have implications for U-Pb dating (i.e., explanation of discordant ages), and noble gas escape systematics in zircon (i.e., volume diffusion or fast pathway escape). The possibility also exists for using 222Rn, or other noble gasses, as a measure of defect density within crystals.

  16. Low heat flow inferred from >4Gyr zircons suggests Hadean plate boundary interactions

    NASA Astrophysics Data System (ADS)

    Hopkins, Michelle; Harrison, T. Mark; Manning, Craig E.

    2008-11-01

    The first ~600 million years of Earth history (the `Hadean' eon) remain poorly understood, largely because there is no rock record dating from that era. Detrital Hadean igneous zircons from the Jack Hills, Western Australia, however, can potentially provide insights into the conditions extant on our planet at that time. Results of geochemical investigations using these ancient grains have been interpreted to suggest the presence of a hydrosphere and continental crust before 4Gyr. An underexploited characteristic of the >4Gyr zircons is their diverse assemblage of mineral inclusions. Here we present an examination of over 400 Hadean zircons from Jack Hills, which shows that some inclusion assemblages are conducive to thermobarometry. Our thermobarometric analyses of 4.02-4.19-Gyr-old inclusion-bearing zircons constrain their magmatic formation conditions to about 700°C and 7kbar. This result implies a near-surface heat flow of ~75mWm-2, about three to five times lower than estimates of Hadean global heat flow. As the only site of magmatism on modern Earth that is characterized by heat flow of about one-quarter of the global average is above subduction zones, we suggest that the magmas from which the Jack Hills Hadean zircons crystallized were formed largely in an underthrust environment, perhaps similar to modern convergent margins.

  17. Controlled Speed Accessory Drive demonstration program

    NASA Technical Reports Server (NTRS)

    Hoehn, F. W.

    1981-01-01

    A Controlled Speed Accessory Drive System was examined in an effort to improve the fuel economy of passenger cars. Concept feasibility and the performance of a typical system during actual road driving conditions were demonstrated. The CSAD system is described as a mechanical device which limits engine accessory speeds, thereby reducing parasitic horsepower losses and improving overall vehicle fuel economy. Fuel consumption data were compiled for fleets of GSA vehicles. Various motor pool locations were selected, each representing different climatic conditions. On the basis of a total accumulated fleet usage of nearly three million miles, an overall fuel economy improvement of 6 percent to 7 percent was demonstrated. Coincident chassis dynamometer tests were accomplished on selected vehicles to establish the effect of different accessory drive systems on exhaust emissions, and to evaluate the magnitude of the mileage benefits which could be derived.

  18. Reutilization of accessories in gastrointestinal endoscopic practice.

    PubMed

    Haber, G

    2000-10-01

    The key issues that determine the decision between reusable versus disposable accessories are cost and functionality. In most health-care systems the availability and dissemination of endoscopic services relates directly to the resources (i.e. budget) of that system. Given the limitations of health-care budgets, access to endoscopic services will depend upon the cost efficiency of endoscopic practice. The onus on endoscopists and health-care providers, therefore, is to meticulously evaluate the necessary steps for safe reutilization of accessories. This paper addresses the principles of reuse, quality assurance and particularly disinfection practices. Any change to a more costly disposable accessory policy must bear the responsibility of denied access to endoscopic services in a system with finite resources.

  19. What can zircon ages from the Jack Hills detrital zircon suite really tell us about Hadean geodynamics?

    NASA Astrophysics Data System (ADS)

    Whitehouse, Martin; Nemchin, Alexander

    2015-04-01

    As the only direct sample of the Hadean Earth, detrital zircon grains from the Jack Hills, Western Australia, have been the subject of intense investigation over the almost three decades since their discovery. A wide variety of geochemical and isotopic analyses of these grains, as well as their mineral inclusions, have been used variously to support two fundamentally different models for Hadean geodynamics: (i) Some form of (not necessarily modern-style) plate recycling generating felsic (continental-type?) crust at the boundaries [1, 2], or conversely (ii) the persistence of a long-lived, stagnant basaltic lid within which magmatism occurred as a result of internal temperature perturbations and/or impacts [3, 4], a model also generally consistent with a wide range of observations from post-Hadean geochemical reservoirs. Despite the considerable time and resources expended, the majority of these studies uncritically accept the individual U-Pb zircon ages, even though their veracity is key to many of the interpretations [5, 6]. We report here the results of an in-depth evaluation of all published (and new) U-Pb ages from the Jack Hills zircon suite in order to define age populations that can be used with a high degree of confidence in geodynamic interpretations. A notable problem in the interpretation of U-Pb data from ancient zircon grains (including those as young as the Neoarchean) is that disturbance of the systematics even several 100 Ma after crystallization causes data to spread along the concordia curve without becoming discernably discordant within the relatively large error bounds associated with U/Pb ages from in situ dating methods (e.g. SIMS). While 207Pb/206Pb ages are typically more precise, individually they provide no means to detect Pb-loss-induced younging. However, if two or preferably more analyses have been made in the same zircon growth zone, a reasonable evaluation of the possibility of Pb-loss can be made. In the available Jack Hills zircon

  20. 30 CFR 75.1106-5 - Maintenance and tests of liquefied and nonliquefied compressed gas cylinders; accessories and...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... nonliquefied compressed gas cylinders; accessories and equipment; requirements. 75.1106-5 Section 75.1106-5 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Fire Protection § 75.1106-5 Maintenance and tests...

  1. 30 CFR 75.1106-5 - Maintenance and tests of liquefied and nonliquefied compressed gas cylinders; accessories and...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... nonliquefied compressed gas cylinders; accessories and equipment; requirements. 75.1106-5 Section 75.1106-5 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Fire Protection § 75.1106-5 Maintenance and tests...

  2. Zircon dating of oceanic crustal accretion.

    PubMed

    Lissenberg, C Johan; Rioux, Matthew; Shimizu, Nobumichi; Bowring, Samuel A; Mével, Catherine

    2009-02-20

    Most of Earth's present-day crust formed at mid-ocean ridges. High-precision uranium-lead dating of zircons in gabbros from the Vema Fracture Zone on the Mid-Atlantic Ridge reveals that the crust there grew in a highly regular pattern characterized by shallow melt delivery. Combined with results from previous dating studies, this finding suggests that two distinct modes of crustal accretion occur along slow-spreading ridges. Individual samples record a zircon date range of 90,000 to 235,000 years, which is interpreted to reflect the time scale of zircon crystallization in oceanic plutonic rocks.

  3. Recrystallization and hydrothermal growth of high U-Th zircon in the Weondong deposit, Korea: Record of post-magmatic alteration

    NASA Astrophysics Data System (ADS)

    Park, Changyun; Song, Yungoo; Chung, Donghoon; Kang, Il-Mo; Khulganakhuu, Chuluunbaatar; Yi, Keewook

    2016-09-01

    In this study, we investigate zircons with high U and Th contents of 12,000-24,000 and 11,000-40,000 ppm, respectively, from leucocratic granite in the Weondong region of South Korea. Hydrothermally epitaxial growth textures are observed in addition to four distinct textures with different backscattered electron (BSE) intensities within single zircon crystals. We describe the internal textures of the zircon crystals and define the chemical characteristics of each textural domain. The zircon crystals show internally recrystallized and externally crystallized textures, supporting the concept of post-magmatic fluid control. After crystallization of the primary zircon by late magmatism, four types of secondary textures were developed. The type-I domain shows patchy forms within the primary domain due to the structural and chemical recrystallization of self-irradiated zircon by a fluid-dominated diffusion reaction process. The type-II domain is characterized by a pure zircon composition, mineral inclusions (mainly thorite), and micropores due to chemical recrystallization by a coupled dissolution-reprecipitation process during interaction with aqueous fluids. The type-III domain is the purest zircon, is interconnected with type-II, and formed by a second coupled dissolution-reprecipitation process. The type-IV domain is the hydrothermal recrystallization/overgrowth texture formed by the direct crystallization process from fluorine-enriched, zircon-saturated aqueous fluid. These results indicate that the zircon crystals were formed sequentially or intermittently through multi-genetic processes by post-magmatic fluids. Furthermore, we conclude that F-enriched post-magmatic fluid migrated large amounts of zirconium, resulting in the typical overgrowth texture of zircon.

  4. [Accessory symptomatology and therapy of Gilles de la Tourette's disease].

    PubMed

    Achkova, M; Terziev, D

    1987-01-01

    Eight patients with Gilles de la Tourette's syndrome were examined. They had typical multiple tics and accessory disturbances--impulsive and reactive symptoms. The authors described the classification of accessory symptoms and the therapeutic approaches.

  5. Refractory Materials of Zirconate. Part 2: Synthesis and some properties of strontium, zirconate, calcium zirconate and barium zirconate

    NASA Technical Reports Server (NTRS)

    Okubo, Tsutomo; Yonemochi, Osamu; Nakamura, Kazuo; Maeda, Minoru

    1988-01-01

    Chemical compounds SrZrO3, CaZrO3, and BaZrO3 were synthesized by solid reaction and arc fusion, and their properties examined. Results were as follows: (1) in the synthesis of CaZrO3 by solid reaction, ZrO2 solid solution with cubic form was produced, which then changed into CaZrO3; (2) the BaZrO3 was a cubic form and did not show any transformation, while SrZrO3 and CaZrO3 with an orthorhombic form transformed to a cubic form at high temperature; and (3) the solubility of BaZrO3 in acid and its vaporization rate at a high temperature were greater than those of zirconates.

  6. Applying the Ce-in-zircon oxygen geobarometer to diverse silicic magmatic systems

    NASA Astrophysics Data System (ADS)

    Claiborne, L. L.; Miller, C. F.

    2012-12-01

    Zircon provides information on age, temperature, and composition of the magma from which it grew. In systems such as Mount St. Helens, where zircon is not coeval with the rest of the crystal cargo, it provides the only accessible record of the extended history of the magmatic system, including cycles of intrusion, crystallization and rejuvenation beneath an active volcano (Claiborne et al., 2010). The rare earth elements, which are present in measureable quantities in zircon, provide information about the composition of the magma from which zircon grew. Unique among the generally trivalent rare earth elements, cerium can exist as either trivalent or tetravalent, depending on the oxidation state of the magma. The tetravalent ion is highly compatible in zircon, in the site that usually hosts tetravalent zirconium, and so the amount of Cerium in zircon relative (relative to what would be expected of trivalent Ce) depends the oxidation state of the magma from which it grew. Trail et al. (2011) proposed a calibration based on experimental data that uses the Ce anomaly in zircon as a direct proxy for magma oxidation (fugacity), describing the relationship between Ce in zircon and magma oxygen fugacity as ln(Ce/Ce*)D = (0.1156±0.0050)xln(fO2)+(13860±708)/T-(6.125±0.484). For systems like Mount St. Helens, where the major minerals record only events in the hundreds to thousands of years leading to eruption, (including the Fe-Ti oxides traditionally relied upon for records of oxidation state of the magmas), this presents a novel approach for understanding more extended histories of oxidation of magmas in the tens and hundreds of thousands of years of magmatism at a volcanic center. This calibration also promises to help us better constrain conditions of crystallization in intrusive portions of volcanic systems, as well as plutonic bodes. We apply this new oxygen geobarometer to natural volcanic and plutonic zircons from a variety of tectonic settings, and compare to

  7. Physical, chemical, and mineral properties of the Polonnaruwa stones

    NASA Astrophysics Data System (ADS)

    Wallis, Jamie; Wickramasinghe, N. C.; Wallis, Daryl H.; Miyake, Nori; Wallis, M. K.; Hoover, Richard B.; Samaranayake, Anil; Wickramarathne, Keerthi; Oldroyd, Anthony

    2013-09-01

    We report on the physical, chemical and mineral properties of a series of stone fragments recovered from the North Central Province of Sri Lanka following a witnessed fireball event on 29 December 2012. The stones exhibit highly porous poikilitic textures comprising of isotropic silica-rich/plagioclase-like hosts. Inclusions range in size and shape from mm-sized to smaller subangular grains frequently more fractured than the surrounding host and include ilmenite, olivine (fayalitic), quartz and accessory zircon. Bulk mineral compositions include accessory cristobalite, hercynite, anorthite, wuestite, albite, anorthoclase and the high pressure olivine polymorph wadsleyite, suggesting previous endurance of a shock pressure of ~20 GPa. Further evidence of shock is confirmed by the conversion of all plagioclase to maskelynite. Here the infrared absorption spectra in the region 580 cm-1 to 380 cm-1 due to the Si-O-Si or Si-O-Al absorption band shows a partial shift in the peak at 380 cm-1 towards 480 cm-1 indicating an intermediate position between crystalline and amorphous phase. Host matrix chemical compositions vary between samples, but all are rich in SiO2. Silica-rich melts display a heterogeneous K-enrichment comparable to that reported in a range of non-terrestrial material from rare iron meteorites to LL chondritic breccias and Lunar granites. Bulk chemical compositions of plagioclase-like samples are comparable to reported data e.g. Miller Ranger 05035 (Lunar), while Si-rich samples accord well with mafic and felsic glasses reported in NWA 1664 (Howardite) as well as data for fusion crust present in a variety of meteoritic samples. Triple oxygen isotope results show Δ17O = -0.335 with δ18O (‰ rel. SMOW) values of 17.816 +/- 0.100 and compare well with those of known CI chondrites and are within the range of CI-like (Meta-C) chondrites. Rare earth elemental abundances show a profound Europium anomaly of between 0.7 and 0.9 ppm while CI normalized REE

  8. Physical, Chemical and Mineral Properties of the Polonnaruwa Stones

    NASA Astrophysics Data System (ADS)

    Wallis, Jamie; Wickramasinghe, N. C.; Wallis, Daryl H.; Miyake, Nori; Wallis, M. K.; Hoover, Richard B.; Samaranayake, Anil; Wickramarathne, Keerthi; Oldroyd, Anthony

    We report on the physical, chemical and mineral properties of a series of stone fragments recovered from the North Central Province of Sri Lanka following a witnessed fireball event on 29 December 2012. The stones exhibit highly porous poikilitic textures comprising of isotropic silica-rich/plagioclase-like hosts. Inclusions range in size and shape from mm-sized to smaller subangular grains frequently more fractured than the surrounding host and include ilmenite, olivine (fayalitic), quartz and accessory zircon. Bulk mineral compositions include accessory cristobalite, hercynite, anorthite, wuestite, albite, anorthoclase and the high pressure olivine polymorph wadsleyite, suggesting previous endurance of a shock pressure of ~20GPa. Further evidence of shock is confirmed by theconversion of all plagioclase to maskelynite. Here the infrared absorption spectra in the region 580 cm-1 to 380 cm-1 due to the Si-O-Si or Si-O-Al absorption band shows a partial shift in the peak at 380 cm-1 towards 480 cm-1 indicating an intermediate position between crystalline and amorphous phase. Host matrix chemical compositions vary between samples, but all are rich in SiO2. Silica-rich melts display a heterogeneous K-enrichment comparable to that reported in a range of nonterrestrial material from rare iron meteorites to LL chondritic breccias and Lunar granites. Bulk chemical compositions of plagioclase-like samples are comparable to reported data e.g. Miller Ranger 05035 (Lunar), while Si-rich samples accord well with mafic and felsic glasses reported in NWA 1664 (Howardite)as well asdata for fusion crust present in a variety of meteoritic samples.Triple oxygen isotope results show Δ17O = .0.335 with δ18O (‰ rel. SMOW) values of 17.816 ± 0.100 and compare well with those of known CI chondrites and are within the range of CI-like (Meta-C) chondrites. Rare earth elemental abundances show a profound Europium anomaly of between 0.7 and 0.9 ppm while CI normalized REE patterns

  9. Perspectives and perils of using U-Pb zircon geochronology to constrain stratigraphic age: lessons from the Permian-Triassic Karoo basin, South Africa

    NASA Astrophysics Data System (ADS)

    Weislogel, A. L.; Mckay, M. P.; Dean, J.; Fildani, A.

    2013-12-01

    The Karoo basin contains an important Carboniferous-Jurassic sedimentary record that chronicles the amalgamation of Pangea, subduction along the southern Panthallasan margin and later opening of the South Atlantic, Southern, and Indian oceans. It also preserves a robust record of the end-Permian extinction, Earth's largest paleobiologic crisis. Fortuitously, this stratigraphic record is interleaved with numerous air-fall volcanic ashes likely derived from a continental magmatic system, part of which is currently exposed in the Choiyoi igneous province of South America. Our U-Pb geochronology of air-fall ash zircon from the Ecca and Beaufort Groups via SHRIMP analysis, along with LA-ICP-MS U-Pb analysis of detrital zircon from interbedded sandstones indicate that magmatic activity of this system likely persisted for at least 50 Ma. Particularly noteworthy is that uppermost Ecca Group detrital zircon signature exhibits few Precambrian ages and abundant Permian-Triassic ages; thus, by the start of marginal marine deposition, Karoo basin clastic influx was primarily sourced by some part of the Permian-Triassic Panthallassic magmatic system (i.e., the Choiyoi igneous province or its southern equivalent). Detrital zircon U-Pb ages suggest initial zircon formed within this magmatic system by ~300 Ma and that the apex of zircon crystallization occurred at ~265-275 Ma, after which, zircon crystallization decreased through time. We hypothesize that over the long duration of magmatic evolution, the melt began to become depleted with respect to zircon, such that by ~260 Ma, the melt became primarily undersaturated with respect to zircon. As a result, zircon was no longer a major accessory phase and ultimately after ~250 Ma was extruded only in scant trace amounts. This interpretation is also supported by U-Pb zircon geochronology on a few dozen Ecca and Beaufort Group ashes from across the Karoo basin. Individual ash ages were determined from statistically-robust, coherent

  10. Electronic Position Sensor for Power Operated Accessory

    DOEpatents

    Haag, Ronald H.; Chia, Michael I.

    2005-05-31

    An electronic position sensor for use with a power operated vehicle accessory, such as a power liftgate. The position sensor includes an elongated resistive circuit that is mounted such that it is stationary and extends along the path of a track portion of the power operated accessory. The position sensor further includes a contact nub mounted to a link member that moves within the track portion such that the contact nub is slidingly biased against the elongated circuit. As the link member moves under the force of a motor-driven output gear, the contact nub slides along the surface of the resistive circuit, thereby affecting the overall resistance of the circuit. The position sensor uses the overall resistance to provide an electronic position signal to an ECU, wherein the signal is indicative of the absolute position of the power operated accessory. Accordingly, the electronic position sensor is capable of providing an electronic signal that enables the ECU to track the absolute position of the power operated accessory.

  11. Biting palsy of the accessory nerve.

    PubMed Central

    Paljärvi, L; Partanen, J

    1980-01-01

    A young man was bitten by his girl friend at the anterior border of the left trapezius muscle. Weakness of the trapezius resulted and a longstanding ache in the shoulder developed. Clinically and neurophysiologically, an axonotmesis type crush injury of the accessory nerve was verified. PMID:7431036

  12. 14 CFR 29.1163 - Powerplant accessories.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... involved; (2) Use the provisions on the engine for mounting; and (3) Be sealed in such a way as to prevent contamination of the engine oil system and the accessory system. (b) Electrical equipment subject to arcing or... be a hazard if they malfunction, there must be means to prevent their hazardous rotation...

  13. 14 CFR 29.1163 - Powerplant accessories.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... involved; (2) Use the provisions on the engine for mounting; and (3) Be sealed in such a way as to prevent contamination of the engine oil system and the accessory system. (b) Electrical equipment subject to arcing or... be a hazard if they malfunction, there must be means to prevent their hazardous rotation...

  14. Normal variants of the accessory hemiazygos vein

    PubMed Central

    Blackmon, J M; Franco, A

    2011-01-01

    This short communication describes two normal variants of the accessory hemiazygous vein in a 15-year-old female. The article demonstrates that knowledge of the aberrant venous anatomy and the collateral pathway is important for the practising radiologist. PMID:21697414

  15. 21 CFR 890.3910 - Wheelchair accessory.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Wheelchair accessory. 890.3910 Section 890.3910 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3910...

  16. 21 CFR 890.3910 - Wheelchair accessory.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Wheelchair accessory. 890.3910 Section 890.3910 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3910...

  17. 21 CFR 890.3910 - Wheelchair accessory.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Wheelchair accessory. 890.3910 Section 890.3910 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3910...

  18. 21 CFR 890.3910 - Wheelchair accessory.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Wheelchair accessory. 890.3910 Section 890.3910 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3910...

  19. 21 CFR 890.3910 - Wheelchair accessory.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Wheelchair accessory. 890.3910 Section 890.3910 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3910...

  20. 21 CFR 868.5860 - Pressure tubing and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Pressure tubing and accessories. 868.5860 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5860 Pressure tubing and accessories. (a) Identification. Pressure tubing and accessories are flexible or rigid devices intended...

  1. 21 CFR 868.5860 - Pressure tubing and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Pressure tubing and accessories. 868.5860 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5860 Pressure tubing and accessories. (a) Identification. Pressure tubing and accessories are flexible or rigid devices intended...

  2. 21 CFR 868.5860 - Pressure tubing and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Pressure tubing and accessories. 868.5860 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5860 Pressure tubing and accessories. (a) Identification. Pressure tubing and accessories are flexible or rigid devices intended...

  3. 14 CFR 23.1192 - Engine accessory compartment diaphragm.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Engine accessory compartment diaphragm. 23... Powerplant Powerplant Fire Protection § 23.1192 Engine accessory compartment diaphragm. For aircooled radial... accessory compartment by a diaphragm that meets the firewall requirements of § 23.1191....

  4. 14 CFR 23.1192 - Engine accessory compartment diaphragm.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine accessory compartment diaphragm. 23... Powerplant Powerplant Fire Protection § 23.1192 Engine accessory compartment diaphragm. For aircooled radial... accessory compartment by a diaphragm that meets the firewall requirements of § 23.1191....

  5. 14 CFR 25.1192 - Engine accessory section diaphragm.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Engine accessory section diaphragm. 25.1192....1192 Engine accessory section diaphragm. For reciprocating engines, the engine power section and all portions of the exhaust system must be isolated from the engine accessory compartment by a diaphragm...

  6. 14 CFR 23.1192 - Engine accessory compartment diaphragm.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Engine accessory compartment diaphragm. 23... Powerplant Powerplant Fire Protection § 23.1192 Engine accessory compartment diaphragm. For aircooled radial... accessory compartment by a diaphragm that meets the firewall requirements of § 23.1191....

  7. 14 CFR 25.1192 - Engine accessory section diaphragm.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Engine accessory section diaphragm. 25.1192....1192 Engine accessory section diaphragm. For reciprocating engines, the engine power section and all portions of the exhaust system must be isolated from the engine accessory compartment by a diaphragm...

  8. 14 CFR 25.1192 - Engine accessory section diaphragm.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Engine accessory section diaphragm. 25.1192....1192 Engine accessory section diaphragm. For reciprocating engines, the engine power section and all portions of the exhaust system must be isolated from the engine accessory compartment by a diaphragm...

  9. 14 CFR 23.1192 - Engine accessory compartment diaphragm.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Engine accessory compartment diaphragm. 23... Powerplant Powerplant Fire Protection § 23.1192 Engine accessory compartment diaphragm. For aircooled radial... accessory compartment by a diaphragm that meets the firewall requirements of § 23.1191....

  10. 14 CFR 25.1192 - Engine accessory section diaphragm.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine accessory section diaphragm. 25.1192....1192 Engine accessory section diaphragm. For reciprocating engines, the engine power section and all portions of the exhaust system must be isolated from the engine accessory compartment by a diaphragm...

  11. 21 CFR 876.5540 - Blood access device and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Blood access device and accessories. 876.5540... (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5540 Blood access device and accessories. (a) Identification. A blood access device and accessories is a device intended...

  12. 21 CFR 876.5540 - Blood access device and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Blood access device and accessories. 876.5540... (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5540 Blood access device and accessories. (a) Identification. A blood access device and accessories is a device intended...

  13. 21 CFR 876.5540 - Blood access device and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Blood access device and accessories. 876.5540... (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5540 Blood access device and accessories. (a) Identification. A blood access device and accessories is a device intended...

  14. 21 CFR 876.5540 - Blood access device and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Blood access device and accessories. 876.5540... (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5540 Blood access device and accessories. (a) Identification. A blood access device and accessories is a device intended...

  15. 14 CFR 25.1192 - Engine accessory section diaphragm.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Engine accessory section diaphragm. 25.1192....1192 Engine accessory section diaphragm. For reciprocating engines, the engine power section and all portions of the exhaust system must be isolated from the engine accessory compartment by a diaphragm...

  16. 21 CFR 872.6300 - Rubber dam and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rubber dam and accessories. 872.6300 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6300 Rubber dam and accessories. (a) Identification. A rubber dam and accessories is a device composed of a thin sheet of latex with a hole in...

  17. 21 CFR 872.6300 - Rubber dam and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Rubber dam and accessories. 872.6300 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6300 Rubber dam and accessories. (a) Identification. A rubber dam and accessories is a device composed of a thin sheet of latex with a hole in...

  18. 19 CFR 10.1020 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 1 2014-04-01 2014-04-01 false Accessories, spare parts, or tools. 10.1020... Free Trade Agreement Rules of Origin § 10.1020 Accessories, spare parts, or tools. (a) General. Accessories, spare parts, or tools that are delivered with a good and that form part of the good's...

  19. 19 CFR 10.3020 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 1 2014-04-01 2014-04-01 false Accessories, spare parts, or tools. 10.3020...-Colombia Trade Promotion Agreement Rules of Origin § 10.3020 Accessories, spare parts, or tools. (a) General. Accessories, spare parts, or tools that are delivered with a good and that form part of the...

  20. 19 CFR 10.600 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 19 Customs Duties 1 2012-04-01 2012-04-01 false Accessories, spare parts, or tools. 10.600 Section...-Central America-United States Free Trade Agreement Rules of Origin § 10.600 Accessories, spare parts, or tools. (a) General. Accessories, spare parts, or tools that are delivered with a good and that form...

  1. 19 CFR 10.3020 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 1 2013-04-01 2013-04-01 false Accessories, spare parts, or tools. 10.3020...-Colombia Trade Promotion Agreement Rules of Origin § 10.3020 Accessories, spare parts, or tools. (a) General. Accessories, spare parts, or tools that are delivered with a good and that form part of the...

  2. 19 CFR 10.2020 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 1 2014-04-01 2014-04-01 false Accessories, spare parts, or tools. 10.2020... Trade Promotion Agreement Rules of Origin § 10.2020 Accessories, spare parts, or tools. (a) General. Accessories, spare parts, or tools that are delivered with a good and that form part of the good's...

  3. 19 CFR 10.600 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 1 2013-04-01 2013-04-01 false Accessories, spare parts, or tools. 10.600 Section...-Central America-United States Free Trade Agreement Rules of Origin § 10.600 Accessories, spare parts, or tools. (a) General. Accessories, spare parts, or tools that are delivered with a good and that form...

  4. 19 CFR 10.1020 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 19 Customs Duties 1 2012-04-01 2012-04-01 false Accessories, spare parts, or tools. 10.1020... Free Trade Agreement Rules of Origin § 10.1020 Accessories, spare parts, or tools. (a) General. Accessories, spare parts, or tools that are delivered with a good and that form part of the good's...

  5. 19 CFR 10.600 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 1 2011-04-01 2011-04-01 false Accessories, spare parts, or tools. 10.600 Section...-Central America-United States Free Trade Agreement Rules of Origin § 10.600 Accessories, spare parts, or tools. (a) General. Accessories, spare parts, or tools that are delivered with a good and that form...

  6. 19 CFR 10.1020 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 1 2013-04-01 2013-04-01 false Accessories, spare parts, or tools. 10.1020... Free Trade Agreement Rules of Origin § 10.1020 Accessories, spare parts, or tools. (a) General. Accessories, spare parts, or tools that are delivered with a good and that form part of the good's...

  7. 19 CFR 10.600 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Accessories, spare parts, or tools. 10.600 Section...-Central America-United States Free Trade Agreement Rules of Origin § 10.600 Accessories, spare parts, or tools. (a) General. Accessories, spare parts, or tools that are delivered with a good and that form...

  8. 19 CFR 10.600 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 1 2014-04-01 2014-04-01 false Accessories, spare parts, or tools. 10.600 Section...-Central America-United States Free Trade Agreement Rules of Origin § 10.600 Accessories, spare parts, or tools. (a) General. Accessories, spare parts, or tools that are delivered with a good and that form...

  9. 21 CFR 878.3925 - Plastic surgery kit and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Plastic surgery kit and accessories. 878.3925... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Prosthetic Devices § 878.3925 Plastic surgery kit and accessories. (a) Identification. A plastic surgery kit and accessories is a device intended...

  10. 21 CFR 878.3925 - Plastic surgery kit and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Plastic surgery kit and accessories. 878.3925... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Prosthetic Devices § 878.3925 Plastic surgery kit and accessories. (a) Identification. A plastic surgery kit and accessories is a device intended...

  11. 21 CFR 878.3925 - Plastic surgery kit and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Plastic surgery kit and accessories. 878.3925... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Prosthetic Devices § 878.3925 Plastic surgery kit and accessories. (a) Identification. A plastic surgery kit and accessories is a device intended...

  12. 21 CFR 878.3925 - Plastic surgery kit and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Plastic surgery kit and accessories. 878.3925... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Prosthetic Devices § 878.3925 Plastic surgery kit and accessories. (a) Identification. A plastic surgery kit and accessories is a device intended...

  13. 21 CFR 878.3925 - Plastic surgery kit and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Plastic surgery kit and accessories. 878.3925... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Prosthetic Devices § 878.3925 Plastic surgery kit and accessories. (a) Identification. A plastic surgery kit and accessories is a device intended...

  14. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Abrasive device and accessories. 872.6010 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and accessories. (a) Identification. An abrasive device and accessories is a device constructed of various...

  15. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Abrasive device and accessories. 872.6010 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and accessories. (a) Identification. An abrasive device and accessories is a device constructed of various...

  16. 21 CFR 872.3980 - Endosseous dental implant accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Endosseous dental implant accessories. 872.3980... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3980 Endosseous dental implant accessories. (a) Identification. Endosseous dental implant accessories are manually powered devices...

  17. 21 CFR 872.4920 - Dental electrosurgical unit and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental electrosurgical unit and accessories. 872... SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4920 Dental electrosurgical unit and accessories. (a) Identification. A dental electrosurgical unit and accessories is an...

  18. 21 CFR 872.4200 - Dental handpiece and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental handpiece and accessories. 872.4200 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4200 Dental handpiece and accessories. (a) Identification. A dental handpiece and accessories is an AC-powered, water-powered, air-powered, or...

  19. 21 CFR 872.6250 - Dental chair and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental chair and accessories. 872.6250 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6250 Dental chair and accessories. (a) Identification. A dental chair and accessories is a device, usually AC-powered, in which a patient sits....

  20. 21 CFR 872.6640 - Dental operative unit and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental operative unit and accessories. 872.6640... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6640 Dental operative unit and accessories. (a) Identification. A dental operative unit and accessories is an AC-powered device that...

  1. 21 CFR 872.6250 - Dental chair and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Dental chair and accessories. 872.6250 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6250 Dental chair and accessories. (a) Identification. A dental chair and accessories is a device, usually AC-powered, in which a patient sits....

  2. 21 CFR 872.3980 - Endosseous dental implant accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Endosseous dental implant accessories. 872.3980... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3980 Endosseous dental implant accessories. (a) Identification. Endosseous dental implant accessories are manually powered devices...

  3. 21 CFR 872.4200 - Dental handpiece and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Dental handpiece and accessories. 872.4200 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4200 Dental handpiece and accessories. (a) Identification. A dental handpiece and accessories is an AC-powered, water-powered, air-powered, or...

  4. 21 CFR 872.3980 - Endosseous dental implant accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Endosseous dental implant accessories. 872.3980... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3980 Endosseous dental implant accessories. (a) Identification. Endosseous dental implant accessories are manually powered devices...

  5. 21 CFR 872.4200 - Dental handpiece and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Dental handpiece and accessories. 872.4200 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4200 Dental handpiece and accessories. (a) Identification. A dental handpiece and accessories is an AC-powered, water-powered, air-powered, or...

  6. 21 CFR 872.4200 - Dental handpiece and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Dental handpiece and accessories. 872.4200 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4200 Dental handpiece and accessories. (a) Identification. A dental handpiece and accessories is an AC-powered, water-powered, air-powered, or...

  7. 21 CFR 872.3980 - Endosseous dental implant accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Endosseous dental implant accessories. 872.3980... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3980 Endosseous dental implant accessories. (a) Identification. Endosseous dental implant accessories are manually powered devices...

  8. 21 CFR 872.4200 - Dental handpiece and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Dental handpiece and accessories. 872.4200 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4200 Dental handpiece and accessories. (a) Identification. A dental handpiece and accessories is an AC-powered, water-powered, air-powered, or...

  9. 21 CFR 872.3980 - Endosseous dental implant accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Endosseous dental implant accessories. 872.3980... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3980 Endosseous dental implant accessories. (a) Identification. Endosseous dental implant accessories are manually powered devices...

  10. 21 CFR 872.6640 - Dental operative unit and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Dental operative unit and accessories. 872.6640... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6640 Dental operative unit and accessories. (a) Identification. A dental operative unit and accessories is an AC-powered device that...

  11. 21 CFR 872.6250 - Dental chair and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Dental chair and accessories. 872.6250 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6250 Dental chair and accessories. (a) Identification. A dental chair and accessories is a device, usually AC-powered, in which a patient sits....

  12. 21 CFR 872.6250 - Dental chair and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Dental chair and accessories. 872.6250 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6250 Dental chair and accessories. (a) Identification. A dental chair and accessories is a device, usually AC-powered, in which a patient sits....

  13. 21 CFR 872.6640 - Dental operative unit and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Dental operative unit and accessories. 872.6640... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6640 Dental operative unit and accessories. (a) Identification. A dental operative unit and accessories is an AC-powered device that...

  14. 21 CFR 872.6640 - Dental operative unit and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Dental operative unit and accessories. 872.6640... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6640 Dental operative unit and accessories. (a) Identification. A dental operative unit and accessories is an AC-powered device that...

  15. 21 CFR 872.6250 - Dental chair and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Dental chair and accessories. 872.6250 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6250 Dental chair and accessories. (a) Identification. A dental chair and accessories is a device, usually AC-powered, in which a patient sits....

  16. 21 CFR 872.4120 - Bone cutting instrument and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Bone cutting instrument and accessories. 872.4120... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4120 Bone cutting instrument and accessories. (a) Identification. A bone cutting instrument and accessories is a metal device intended for...

  17. 21 CFR 872.4120 - Bone cutting instrument and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Bone cutting instrument and accessories. 872.4120... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4120 Bone cutting instrument and accessories. (a) Identification. A bone cutting instrument and accessories is a metal device intended for...

  18. 21 CFR 872.4120 - Bone cutting instrument and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Bone cutting instrument and accessories. 872.4120... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4120 Bone cutting instrument and accessories. (a) Identification. A bone cutting instrument and accessories is a metal device intended for...

  19. 21 CFR 872.4120 - Bone cutting instrument and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Bone cutting instrument and accessories. 872.4120... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4120 Bone cutting instrument and accessories. (a) Identification. A bone cutting instrument and accessories is a metal device intended for...

  20. 21 CFR 872.4120 - Bone cutting instrument and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Bone cutting instrument and accessories. 872.4120... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4120 Bone cutting instrument and accessories. (a) Identification. A bone cutting instrument and accessories is a metal device intended for...

  1. 21 CFR 878.4700 - Surgical microscope and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Surgical microscope and accessories. 878.4700 Section 878.4700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... microscope and accessories. (a) Identification. A surgical microscope and accessories is an AC-powered...

  2. 21 CFR 878.4700 - Surgical microscope and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Surgical microscope and accessories. 878.4700 Section 878.4700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... microscope and accessories. (a) Identification. A surgical microscope and accessories is an AC-powered...

  3. 21 CFR 878.4700 - Surgical microscope and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Surgical microscope and accessories. 878.4700 Section 878.4700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... microscope and accessories. (a) Identification. A surgical microscope and accessories is an AC-powered...

  4. Detection of accessory spleens with indium 111-labeled autologous platelets

    SciTech Connect

    Davis, H.H., II; Varki, A.; Heaton, W.A.; Siegel, B.A.

    1980-01-01

    In two patients with recurrent immune thrombocytopenia, accessory splenic tissue was demonstrated by radionuclide imaging following administration of indium 111-labeled autologous platelets. In one of these patients, no accessory splenic tissue was seen on images obtained with technetium 99m sulfur colloid. This new technique provides a simple means for demonstrating accessory spleens and simultaneously evaluating the life-span of autologous platelets.

  5. 21 CFR 884.6120 - Assisted reproduction accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Assisted reproduction accessories. 884.6120... (CONTINUED) MEDICAL DEVICES OBSTETRICAL AND GYNECOLOGICAL DEVICES Assisted Reproduction Devices § 884.6120 Assisted reproduction accessories. (a) Identification. Assisted reproduction accessories are a group...

  6. 21 CFR 884.6120 - Assisted reproduction accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Assisted reproduction accessories. 884.6120... (CONTINUED) MEDICAL DEVICES OBSTETRICAL AND GYNECOLOGICAL DEVICES Assisted Reproduction Devices § 884.6120 Assisted reproduction accessories. (a) Identification. Assisted reproduction accessories are a group...

  7. 21 CFR 884.6120 - Assisted reproduction accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Assisted reproduction accessories. 884.6120... (CONTINUED) MEDICAL DEVICES OBSTETRICAL AND GYNECOLOGICAL DEVICES Assisted Reproduction Devices § 884.6120 Assisted reproduction accessories. (a) Identification. Assisted reproduction accessories are a group...

  8. 21 CFR 884.6120 - Assisted reproduction accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Assisted reproduction accessories. 884.6120... (CONTINUED) MEDICAL DEVICES OBSTETRICAL AND GYNECOLOGICAL DEVICES Assisted Reproduction Devices § 884.6120 Assisted reproduction accessories. (a) Identification. Assisted reproduction accessories are a group...

  9. 21 CFR 876.5980 - Gastrointestinal tube and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Gastrointestinal tube and accessories. 876.5980... tube and accessories. (a) Identification. A gastrointestinal tube and accessories is a device that..., gastrointestinal string and tubes to locate internal bleeding, double lumen tube for intestinal decompression...

  10. 21 CFR 876.5980 - Gastrointestinal tube and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Gastrointestinal tube and accessories. 876.5980... tube and accessories. (a) Identification. A gastrointestinal tube and accessories is a device that..., gastrointestinal string and tubes to locate internal bleeding, double lumen tube for intestinal decompression...

  11. 21 CFR 876.5980 - Gastrointestinal tube and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Gastrointestinal tube and accessories. 876.5980... tube and accessories. (a) Identification. A gastrointestinal tube and accessories is a device that..., gastrointestinal string and tubes to locate internal bleeding, double lumen tube for intestinal decompression...

  12. 21 CFR 876.5980 - Gastrointestinal tube and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Gastrointestinal tube and accessories. 876.5980... tube and accessories. (a) Identification. A gastrointestinal tube and accessories is a device that..., gastrointestinal string and tubes to locate internal bleeding, double lumen tube for intestinal decompression...

  13. 21 CFR 876.5980 - Gastrointestinal tube and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Gastrointestinal tube and accessories. 876.5980... tube and accessories. (a) Identification. A gastrointestinal tube and accessories is a device that..., gastrointestinal string and tubes to locate internal bleeding, double lumen tube for intestinal decompression...

  14. 21 CFR 878.4700 - Surgical microscope and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Surgical microscope and accessories. 878.4700 Section 878.4700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... microscope and accessories. (a) Identification. A surgical microscope and accessories is an AC-powered...

  15. 21 CFR 878.4700 - Surgical microscope and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Surgical microscope and accessories. 878.4700 Section 878.4700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... microscope and accessories. (a) Identification. A surgical microscope and accessories is an AC-powered...

  16. Isotopic Composition of Oxygen in Lunar Zircons

    NASA Technical Reports Server (NTRS)

    Nemchin, A. A.; Whitehouse, M. J.; Pidgeon, R. T.; Meyer, C.

    2005-01-01

    The recent discovery of heavy oxygen in zircons from the Jack Hills conglomerates Wilde et al. and Mojzsis et al. was interpreted as an indication of presence of liquid water on the surface of Early Earth. The distribution of ages of Jack Hills zircons and lunar zircons appears to be very similar and therefore analysis of oxygen in the lunar grains may provide a reference frame for further study of the early history of the Earth as well as give additional information regarding processes that operated on the Moon. In the present study we have analysed the oxygen isotopic composition of zircon grains from three lunar samples using the Swedish Museum of Natural History CAMECA 1270 ion microprobe. The samples were selected as likely tests for variations in lunar oxygen isotopic composition. Additional information is included in the original extended abstract.

  17. Preliminary study on multi-element profile mapping of crustal and mantle zircons by using Synchrotron Radiation X-ray Fluorescence (SR-XRF)

    NASA Astrophysics Data System (ADS)

    Hasözbek, Altug; Shyam, Badri; Siebel, Wolfgang; Schmitt, Axel; Akay, Erhan; Skinner, Lawrie

    2013-04-01

    Zircon (ZrSiO4) is a mineral of singular importance in the geosciences. Zircon microanalysis has greatly contributed to our understanding of key events in earth's history as certain radioactive heavy elements and their daughter products are well-preserved within the exceptionally stable inorganic matrix of the mineral. A prevailing notion in this field is that zircon, as a mineral, is predominantly a crustal mineral; this has been contested in the last few years with more reports of mantle-derived zircons (Siebel et al., 2009). Zircons enriched from different parts of the upper mantle to lower crust from Turkey (Hasozbek et al. 2010) and Germany (Siebel et al., 2009) will be presented in this study using SR-XRF mapping carried out at beamline 2-IDE at the Advanced Photon Source synchrotron facility (Argonne National Laboratory, USA). The high-resolution (5-10 µm) elemental maps were obtained with collimated and linearly polarized synchrotron radiation (10 to 17 keV) and possess the advantage of being a completely non-destructive technique. Elemental maps of various trace and rare-earth elements along the cross-section of the zircons reveal a zonation-related distribution, which may be used to reveal factors affecting the growth history and dynamics of the crystal formation. Further, abrupt changes in elemental distribution or concentration were found to correspond to faults or inclusions within the zircon crystal. If such observations are found to be applicable for a wide range of samples, elemental mapping with this technique may serve as an important qualitative diagnostic to locating µ-meter inclusions that may be challenging to identify using other techniques (ICP-MS LA, SHRIMP,…) Through these preliminary elemental profile mapping studies of crustal and mantle zircons using SR-XRF methods, we aim to highlight a relatively quick and promising analytical method that may be used to study various geological problems.

  18. Recognizing the Geochemical Consequences of Zircon Alteration at Jack Hills, Western Australia

    NASA Astrophysics Data System (ADS)

    Bell, E. A.; Boehnke, P.; Harrison, T. M.

    2014-12-01

    Detrital zircons from Jack Hills, Western Australia are the best known >4 Ga terrestrial mineral record. As their ca. 3 Ga host quartzite experienced several documented Precambrian metamorphic events, it is unsurprising that various alteration features have been suggested or identified in the zircons. Using these grains to understand early Earth conditions requires knowledge to what extent they have been altered. We have used 200 ion microprobe δ18O and 67 trace element analyses of these zircons, together with backscattered electron and cathodoluminescence imaging, to assess differences between spots falling on crack-bearing vs. uncracked surfaces. Analyses on uncracked surfaces were further subdivided into those within magmatic zonations versus those in altered regions. We have combined the results with data from previous studies of Jack Hills zircons to identify alteration signatures and their mechanisms. Analyses on cracks overlap the field of uncracked regions in terms of most variables, but also display trends toward distinct compositions. Regions with altered zonationare often intermediate between magmatic and cracked regions but also overlap magmatic regions in other variables. Clear alteration signals include high P (>1000 ppm), high LREE/HREE (Nd/Yb (N) >0.01), high Ti (>900°C apparent Txlln), high Fe (>1000 ppm), and low HREE/MREE (Yb/Gd (N) <10). Cracks and altered regions are more likely to show high Th/U, low Ce/Ce*, and low δ18O, but the considerable overlap with magmatic regions limits the diagnostic usefulness of these variables. Crack-associated alteration is likely due to the extensive Fe-Ti oxide and xenotime mineralization seen in the zircons. Many but not all CL-dark regions are consistent with solid-state recrystallization. Bright regions cross-cutting magmatic zonation are evident in some zircons, but we have not yet identified a diagnostic signature of this alteration mode.Mineral inclusions falling on and away from cracks show distinct

  19. U-Pb zircon geochronology and phase equilibria modelling of a mafic eclogite from the Sumdo complex of south-east Tibet: Insights into prograde zircon growth and the assembly of the Tibetan plateau

    NASA Astrophysics Data System (ADS)

    Weller, O. M.; St-Onge, M. R.; Rayner, N.; Waters, D. J.; Searle, M. P.; Palin, R. M.

    2016-10-01

    The Sumdo complex is a Permian-Triassic eclogitic metamorphic belt in south-east Tibet, which marks the location of a suture zone that separates the northern and southern Lhasa terranes. An integrated geochronological and petrological study of a mafic eclogite from the complex has constrained its tectonometamorphic history and provides a case study of zircon growth in eclogite as a product of prograde dissolution-precipitation. In situ U-Pb geochronology indicates that the eclogite contains a single population of zircon with a crystallisation age of 273.6 ± 2.8 Ma. The morphology and chemistry of the zircon grains are consistent with growth by dissolution-precipitation of protolith magmatic zircon. The presence of zircon grains as inclusions in the cores of peak phases indicates that zircon dissolution-precipitation occurred during prograde metamorphism, and calculated pressure and temperature conditions over which mineral inclusions in zircon are stable suggest that the zircon most likely precipitated at ~15.5-16.5 kbar and 500-560 °C. Subsequent peak metamorphism is calculated to have reached pressure-temperature conditions of 27 ± 1 kbar and 670 ± 50 °C. Previous studies, which have documented a range of peak metamorphic conditions from high- to ultrahigh-pressure at c. 266-230 Ma, indicate that the Sumdo complex is a composite belt that experienced protracted eclogite exhumation. The results of this study are consistent with this interpretation, and extend the age range of high-pressure metamorphism in the complex to over 40 Myr. Analysis of published pressure-temperature-time data indicates two systematic behaviours within this spread. First, peak metamorphic temperatures declined over time. Second, eclogite exhumation occurred in two discrete intervals: soon after formation, and during the demise of the subduction zone. The latter behaviour serves as a reminder that eclogite exhumation is the exception rather than the rule.

  20. Elastic properties of minerals

    SciTech Connect

    Aleksandrov, K.S.; Prodaivoda, G.T.

    1993-09-01

    Investigations of the elastic properties of the main rock-forming minerals were begun by T.V. Ryzhova and K.S. Aleksandrov over 30 years ago on the initiative of B.P. Belikov. At the time, information on the elasticity of single crystals in general, and especially of minerals, was very scanty. In the surveys of that time there was information on the elasticity of 20 or 30 minerals. These, as a rule, did not include the main rock-forming minerals; silicates were represented only by garnets, quartz, topaz, tourmaline, zircon, beryl, and staurolite, which are often found in nature in the form of large and fairly high-quality crystals. Then and even much later it was still necessary to prove a supposition which now seems obvious: The elastic properties of rocks, and hence the velocities of elastic (seismic) waves in the earth`s crust, are primarily determined by the elastic characteristics of the minerals composing these rocks. Proof of this assertion, with rare exceptions of mono-mineralic rocks (marble, quartzite, etc.) cannot be obtained without information on the elasticities of a sufficiently large number of minerals, primarily framework, layer, and chain silicates which constitute the basis of most rocks. This also served as the starting point and main problem of the undertakings of Aleksandrov, Ryzhova, and Belikov - systematic investigations of the elastic properties of minerals and then of various rocks. 108 refs., 7 tabs.

  1. The not-so-sublime early Earth recorded in Hadean zircons

    NASA Astrophysics Data System (ADS)

    Cavosie, A. J.

    2011-12-01

    The first few hundred million years following accretion is the least understood eon in the geologic time scale- the Hadean. This poorly defined eon continues to both challenge and fascinate scientists seeking to understand the early Earth, as the most profound planet-wide transition in Earth history occurred during the Hadean: the post-accretion transformation from a meteorite impact dominated, partially molten, steam covered mafic surface on a 'Hot Earth', to a solidified, granitoid-bearing, water covered, life-supporting 'Cool Earth'. Intact rocks from the Hadean have not been identified; other means are thus required to study early Earth processes, such as the appearance, formation, and processing of evolved crust, duration of early impacts and magma oceans, the appearance of liquid water and oceans, and ultimately, stabilization of habitats for life. Hadean detrital zircons found in younger sedimentary rocks in Australia, China, and the USA constitute a mineral record from the early Earth that enables 'ground truth' constraints to be placed on early Earth processes. Hadean zircons are complicated and originate from myriad sources; identification of grains that preserve magmatic composition is critical (as evidenced by growth zoning in CL, concordant U-Pb systematics, trace element abundances and ratios), as many have been modified by secondary processes. Detailed documentation of analyzed material is paramount. A generally consistent understanding of processes on the Hadean Earth is emerging, based on data from well-documented igneous zircons with concordant U-Pb systems: (1) A record of continuous magmatism and rock-forming events starting at 4.4 Ga is recorded in U-Pb ages of Hadean zircons; no periods of magmatic quiescence occur in the Hadean. (2) Coupled Lu/Hf and U/Pb data require formation of evolved crust from extracted Hadean reservoirs by 4.5 to 4.4 Ga. (3) Mineral inclusion suites, low Ti and high Li abundances, trace elements (U-Yb), and elevated

  2. The crust-mantle interaction in continental subduction channels: Zircon evidence from orogenic peridotite in the Sulu orogen

    NASA Astrophysics Data System (ADS)

    Li, Hai-Yong; Chen, Ren-Xu; Zheng, Yong-Fei; Hu, Zhaochu

    2016-02-01

    A combined secondary ion mass spectrometer and laser ablation-(multicollector)-inductively coupled plasma mass spectrometer study of zircon U-Pb ages, trace elements, and O and Hf isotopes was carried out for orogenic peridotite and its host gneiss in the Sulu orogen. Newly grown zircon domains exhibit weak zoning or no zoning, relatively low Th/U ratios (<0.1), low heavy rare earth element (HREE) contents, steep middle rare earth element-HREE patterns, negative Eu anomalies, and negative to low δ18O values of -11.3 to 0.9‰ and U-Pb ages of 220 ± 2 to 231 ± 4 Ma. Thus, these zircons would have grown from metasomatic fluids during the early exhumation of deeply subducted continental crust. The infiltration of metasomatic fluids into the peridotite is also indicated by the occurrence of hydrous minerals such as amphibole, serpentine, and chlorite. In contrast, relict zircon domains exhibit magmatic zircon characteristics. Their U-Pb ages and trace element and Hf-O isotope compositions are similar to those for protolith zircons from ultrahigh-pressure metamorphic rocks in the Dabie-Sulu orogenic belt. Thus, these relict magmatic zircons would be physically transported into the peridotite by metasomatic fluids originated from the deeply subducted continental crust. Therefore, the peridotite underwent metasomatism by aqueous solutions derived from dehydration of the deeply subducted continental crust during the early exhumation. It is these crustally derived fluids that would have brought not only such chemical components as Zr and Si but also tiny zircon grains from the deeply subducted crustal rocks into the peridotite at the slab-mantle interface in continental subduction channels. As such, the orogenic peridotite records the crust-mantle interaction at the deep continental subduction zone.

  3. U-Pb Detrital Zircon Ages from Sarawak: Changes in Provenance Reflecting the Tectonic Evolution of Southeast Asia

    NASA Astrophysics Data System (ADS)

    Breitfeld, H. T.; Galin, T.; Hall, R.

    2014-12-01

    Sarawak is located on the northern edge of Sundaland in NW Borneo. Five sedimentary basins are distinguished with ages from Triassic to Cenozoic. New light mineral, heavy mineral and U-Pb detrital zircon ages show differences in provenance reflecting the tectonic evolution of the region. The oldest clastic sediments are Triassic of the Sadong-Kuching Basin and were sourced by a Carnian to Norian volcanic arc and erosion of Cathaysian rocks containing zircons of Paleoproterozoic age. Sandstones of the Upper Jurassic to Cretaceous Bau-Pedawan Basin have distinctive zircon populations indicating a major change of tectonic setting, including initiation of subduction below present-day West Sarawak in the Late Jurassic. A wide range of inherited zircon ages indicates various Cathaysian fragments as major source areas and the arrival of the SW Borneo Block following subduction beneath the Schwaner Mountains in the early Late Cretaceous. After collision of the SW Borneo Block and the microcontinental fragments with Sundaland in the early Late Cretaceous, deep marine sedimentation (Pedawan Formation) ceased, and there was uplift forming the regional Pedawan-Kayan unconformity. Two episodes of extension were responsible for basin development on land from the latest Cretaceous onwards, probably in a strike-slip setting. The first episode formed the Kayan Basin in the Latest Cretaceous (Maastrichtian) to Early Paleocene, and the second formed the Ketungau Basin and the Penrissen Sandstone in the Middle to Late Eocene. Zircons indicate nearby volcanic activity throughout the Early Cenozoic in NW Borneo. Inherited zircon ages indicate an alternation between Borneo and Tin Belt source rocks. A large deep marine basin, the Rajang Basin, formed north of the Lupar Line fault. Zircons from sediments of the Rajang Basin indicate they are of similar age and provenance as the contemporaneous terrestrial sediments to the south suggesting a narrow steep continental Sundaland margin at the

  4. Zircons reveal magma fluxes in the Earth's crust.

    PubMed

    Caricchi, Luca; Simpson, Guy; Schaltegger, Urs

    2014-07-24

    Magma fluxes regulate the planetary thermal budget, the growth of continents and the frequency and magnitude of volcanic eruptions, and play a part in the genesis and size of magmatic ore deposits. However, because a large fraction of the magma produced on the Earth does not erupt at the surface, determinations of magma fluxes are rare and this compromises our ability to establish a link between global heat transfer and large-scale geological processes. Here we show that age distributions of zircons, a mineral often present in crustal magmatic rocks, in combination with thermal modelling, provide an accurate means of retrieving magma fluxes. The characteristics of zircon age populations vary significantly and systematically as a function of the flux and total volume of magma accumulated in the Earth's crust. Our approach produces results that are consistent with independent determinations of magma fluxes and volumes of magmatic systems. Analysis of existing age population data sets using our method suggests that porphyry-type deposits, plutons and large eruptions each require magma input over different timescales at different characteristic average fluxes. We anticipate that more extensive and complete magma flux data sets will serve to clarify the control that the global heat flux exerts on the frequency of geological events such as volcanic eruptions, and to determine the main factors controlling the distribution of resources on our planet.

  5. Multicopper manganese oxidase accessory proteins bind Cu and heme.

    PubMed

    Butterfield, Cristina N; Tao, Lizhi; Chacón, Kelly N; Spiro, Thomas G; Blackburn, Ninian J; Casey, William H; Britt, R David; Tebo, Bradley M

    2015-12-01

    Multicopper oxidases (MCOs) catalyze the oxidation of a diverse group of metal ions and organic substrates by successive single-electron transfers to O2 via four bound Cu ions. MnxG, which catalyzes MnO2 mineralization by oxidizing both Mn(II) and Mn(III), is unique among multicopper oxidases in that it carries out two energetically distinct electron transfers and is tightly bound to accessory proteins. There are two of these, MnxE and MnxF, both approximately 12kDa. Although their sequences are similar to those found in the genomes of several Mn-oxidizing Bacillus species, they are dissimilar to those of proteins with known function. Here, MnxE and MnxF are co-expressed independent of MnxG and are found to oligomerize into a higher order stoichiometry, likely a hexamer. They bind copper and heme, which have been characterized by electron paramagnetic resonance (EPR), X-ray absorption spectroscopy (XAS), and UV-visible (UV-vis) spectrophotometry. Cu is found in two distinct type 2 (T2) copper centers, one of which appears to be novel; heme is bound as a low-spin species, implying coordination by two axial ligands. MnxE and MnxF do not oxidize Mn in the absence of MnxG and are the first accessory proteins to be required by an MCO. This may indicate that Cu and heme play roles in electron transfer and/or Cu trafficking.

  6. International strategic minerals inventory summary report; zirconium

    USGS Publications Warehouse

    Towner, R.R.

    1992-01-01

    Zircon, a zirconium silicate, is currently the most important commercial zirconium-bearing mineral. Baddeleyite, a natural form of zirconia, is less important but has some specific end uses. Both zircon and baddeleyite occur in hard-rock and placer deposits, but at present all zircon production is from placer deposits. Most baddeleyite production is from hard-rock deposits, principally as a byproduct of copper and phosphate-rock mining. World zirconium resources in identified, economically exploitable deposits are about 46 times current production rates. Of these resources, some 71 percent are in South Africa, Australia, and the United States. The principal end uses of zirconium minerals are in ceramic applications and as refractories, abrasives, and mold linings in foundries. A minor amount, mainly of zircon, is used for the production of hafnium-free zirconium metal, which is used principally for sheathing fuel elements in nuclear reactors and in the chemical-processing industry, aerospace engineering, and electronics. Australia and South Africa are the largest zircon producers and account for more than 70 percent of world output; the United States and the Soviet Union account for another 20 percent. South Africa accounts for almost all the world's production of baddeleyite, which is about 2 percent of world production of contained zirconia. Australia and South Africa are the largest exporters of zircon. Unless major new deposits are developed in countries that have not traditionally produced zircon, the pattern of world production is unlikely to change by 2020. The proportions, however, of production that come from existing producing countries may change somewhat.

  7. Deformation-induced trace element redistribution in zircon revealed using atom probe tomography

    NASA Astrophysics Data System (ADS)

    Piazolo, Sandra; La Fontaine, Alexandre; Trimby, Patrick; Harley, Simon; Yang, Limei; Armstrong, Richard; Cairney, Julie M.

    2016-02-01

    Trace elements diffuse negligible distances through the pristine crystal lattice in minerals: this is a fundamental assumption when using them to decipher geological processes. For example, the reliable use of the mineral zircon (ZrSiO4) as a U-Th-Pb geochronometer and trace element monitor requires minimal radiogenic isotope and trace element mobility. Here, using atom probe tomography, we document the effects of crystal-plastic deformation on atomic-scale elemental distributions in zircon revealing sub-micrometre-scale mechanisms of trace element mobility. Dislocations that move through the lattice accumulate U and other trace elements. Pipe diffusion along dislocation arrays connected to a chemical or structural sink results in continuous removal of selected elements (for example, Pb), even after deformation has ceased. However, in disconnected dislocations, trace elements remain locked. Our findings have important implications for the use of zircon as a geochronometer, and highlight the importance of deformation on trace element redistribution in minerals and engineering materials.

  8. Deformation-induced trace element redistribution in zircon revealed using atom probe tomography.

    PubMed

    Piazolo, Sandra; La Fontaine, Alexandre; Trimby, Patrick; Harley, Simon; Yang, Limei; Armstrong, Richard; Cairney, Julie M

    2016-01-01

    Trace elements diffuse negligible distances through the pristine crystal lattice in minerals: this is a fundamental assumption when using them to decipher geological processes. For example, the reliable use of the mineral zircon (ZrSiO4) as a U-Th-Pb geochronometer and trace element monitor requires minimal radiogenic isotope and trace element mobility. Here, using atom probe tomography, we document the effects of crystal-plastic deformation on atomic-scale elemental distributions in zircon revealing sub-micrometre-scale mechanisms of trace element mobility. Dislocations that move through the lattice accumulate U and other trace elements. Pipe diffusion along dislocation arrays connected to a chemical or structural sink results in continuous removal of selected elements (for example, Pb), even after deformation has ceased. However, in disconnected dislocations, trace elements remain locked. Our findings have important implications for the use of zircon as a geochronometer, and highlight the importance of deformation on trace element redistribution in minerals and engineering materials. PMID:26868040

  9. Deformation-induced trace element redistribution in zircon revealed using atom probe tomography

    PubMed Central

    Piazolo, Sandra; La Fontaine, Alexandre; Trimby, Patrick; Harley, Simon; Yang, Limei; Armstrong, Richard; Cairney, Julie M.

    2016-01-01

    Trace elements diffuse negligible distances through the pristine crystal lattice in minerals: this is a fundamental assumption when using them to decipher geological processes. For example, the reliable use of the mineral zircon (ZrSiO4) as a U-Th-Pb geochronometer and trace element monitor requires minimal radiogenic isotope and trace element mobility. Here, using atom probe tomography, we document the effects of crystal–plastic deformation on atomic-scale elemental distributions in zircon revealing sub-micrometre-scale mechanisms of trace element mobility. Dislocations that move through the lattice accumulate U and other trace elements. Pipe diffusion along dislocation arrays connected to a chemical or structural sink results in continuous removal of selected elements (for example, Pb), even after deformation has ceased. However, in disconnected dislocations, trace elements remain locked. Our findings have important implications for the use of zircon as a geochronometer, and highlight the importance of deformation on trace element redistribution in minerals and engineering materials. PMID:26868040

  10. Peninsular terrane basement ages recorded by Paleozoic and Paleoproterozoic zircon in gabbro xenoliths and andesite from Redoubt volcano, Alaska

    USGS Publications Warehouse

    Bacon, Charles R.; Vazquez, Jorge A.; Wooden, Joseph L.

    2012-01-01

    Historically Sactive Redoubt volcano is an Aleutian arc basalt-to-dacite cone constructed upon the Jurassic–Early Tertiary Alaska–Aleutian Range batholith. The batholith intrudes the Peninsular tectonostratigraphic terrane, which is considered to have developed on oceanic basement and to have accreted to North America, possibly in Late Jurassic time. Xenoliths in Redoubt magmas have been thought to be modern cumulate gabbros and fragments of the batholith. However, new sensitive high-resolution ion microprobe (SHRIMP) U-Pb ages for zircon from gabbro xenoliths from a late Pleistocene pyroclastic deposit are dominated by much older, ca. 310 Ma Pennsylvanian and ca. 1865 Ma Paleoproterozoic grains. Zircon age distributions and trace-element concentrations indicate that the ca. 310 Ma zircons date gabbroic intrusive rocks, and the ca. 1865 Ma zircons also are likely from igneous rocks in or beneath Peninsular terrane basement. The trace-element data imply that four of five Cretaceous–Paleocene zircons, and Pennsylvanian low-U, low-Th zircons in one sample, grew from metamorphic or hydrothermal fluids. Textural evidence of xenocrysts and a dominant population of ca. 1865 Ma zircon in juvenile crystal-rich andesite from the same pyroclastic deposit show that this basement has been assimilated by Redoubt magma. Equilibration temperatures and oxygen fugacities indicated by Fe-Ti–oxide minerals in the gabbros and crystal-rich andesite suggest sources near the margins of the Redoubt magmatic system, most likely in the magma accumulation and storage region currently outlined by seismicity and magma petrology at ∼4–10 km below sea level. Additionally, a partially melted gabbro from the 1990 eruption contains zircon with U-Pb ages between ca. 620 Ma and ca. 1705 Ma, as well as one zircon with a U-Th disequilibrium model age of 0 ka. The zircon ages demonstrate that Pennsylvanian, and probably Paleoproterozoic, igneous rocks exist in, or possibly beneath, Peninsular

  11. Elucidating the magmatic history of the Austurhorn silicic intrusive complex (southeast Iceland) using zircon elemental and isotopic geochemistry and geochronology

    NASA Astrophysics Data System (ADS)

    Padilla, A. J.; Miller, C. F.; Carley, T. L.; Economos, R. C.; Schmitt, A. K.; Coble, M. A.; Wooden, J. L.; Fisher, C. M.; Vervoort, J. D.; Hanchar, J. M.

    2016-09-01

    The Austurhorn intrusive complex (AIC) in southeast Iceland comprises large bodies of granophyre and gabbro, and a mafic-silicic composite zone (MSCZ) that exemplifies magmatic interactions common in Icelandic silicic systems. Despite being one of Iceland's best-studied intrusions, few studies have included detailed analyses of zircon, a mineral widely recognized as a valuable tracer of the history and evolution of its parental magma(s). In this study, we employ high spatial resolution zircon elemental and isotopic geochemistry and U-Pb geochronology as tools for elucidating the complex construction and magmatic evolution of Austurhorn's MSCZ. The trace element compositions of AIC zircon crystals form a broad but coherent array that partly overlaps with the geochemical signature for zircons from Icelandic silicic volcanic rocks. Typical of Icelandic zircons, Hf concentrations are relatively low (<10,000 ppm) and Ti concentrations range from 5 to 40 ppm (Ti-in-zircon model temperatures = 761-981 °C). Zircon δ18O values vary from +2.2 to +4.8 ‰, consistent with magmatic zircons from other Icelandic silicic rocks, and preserve evidence for recycling of hydrothermally altered crust as a significant contribution to the generation of silicic magmas within the AIC. Zircon ɛ Hf values generally range from +11 to +15. This range overlaps with that of Icelandic basalts from off-rift settings as well as the least depleted rift basalts, suggesting that the AIC developed within a transitional rift environment. In situ zircon U-Pb ages yield a weighted mean of 6.52 ± 0.03 Ma for the entire complex, but span a range of ~320 kyr, from 6.35 ± 0.08 to 6.67 ± 0.06 Ma (2 σ SE). Gabbros and the most silicic units make up the older part of this range, while granophyres and intermediate units make up the younger part of the complex, consistent with field relationships. We interpret the ~320 kyr range in zircon ages to represent the approximate timescale of magmatic construction

  12. [Accessory renal arteries in human fetuses].

    PubMed

    Gościcka, D; Szpinda, M; Kochan, J

    1996-12-01

    Using conventional anatomical methods, renal arteries of 140 human fetuses were studied. It was found (21.1%) that the accessory renal arteries occurred in a three-fold manner: 1. as single arteries (19.2%), 2. as double arteries (2.1%) and 3. as triplex arteries (0.7%). More often they originated from the right part of the circumference of the abdominal aorta, mainly in the female fetuses. These arteries penetrated the following segments of the kidney: the inferior (12.9%), the superior (2.3%), the anterior inferior (2.8%), the posterior (2.1%) and the anterior superior (1.5%). They crossed the renal pelvis more often in front (12.2%) than from behind of it (5%). The frequency of the occurrence of the accessory arteries depends not from the age of the fetus. PMID:9082875

  13. New ion microprobe U-Pb analyses on unpolished zircon surfaces and polished grain interiors from the 28 Ma Fish Canyon Tuff reveal a protracted crystallization history

    NASA Astrophysics Data System (ADS)

    Coble, M. A.

    2013-12-01

    U-Pb analyses on surfaces and polished interiors of Oligocene Fish Canyon Tuff (FCT) zircon are investigated to better constrain the disparity in FCT ages measured by different isotopic techniques. FCT sanidine is a widely used geochronology standard for K-Ar and 40Ar/39Ar analyses with reported ages ranging from ~27.6-28.3 Ma. In comparison, published U-Pb ID-TIMS zircon ages using chemical or mechanical abrasion methods range from ~28.2 to 28.6 Ma. New 206U-238Pb SHRIMP-RG ion microprobe ages were obtained on untreated, unpolished FCT zircon surfaces as well as from polished zircon interiors. FCT zircon was mounted with primary age standard Temora-2 (416.8 Ma) and secondary zircon standard early-erupted Bishop Tuff (0.767 Ma) by pressing euhedral grains into pliable indium metal leaving the exterior surfaces exposed. The high spatial resolution of the ion-microprobe produced analytical pits 25-30 μm in diameter and 4-6 μm deep (~8 to 9 nA primary O2- beam), allowing only the youngest portion of the zircon to be targeted, while avoiding abundant mineral and glass inclusions pervasive in FCT zircons. The 230Th-corrected 206Pb-238U weighted mean age for FCT zircon surfaces is 28.03×0.17 Ma (2σ, n=38, MSWD=1.07, Th/Urock=2.2) and for Bishop Tuff zircon surfaces is 0.763×0.006 Ma (2σ, n=25, MSWD=0.88, Th/Urock=2.81) analyzed over three analytical sessions. Calculated ages for FCT zircon surfaces are insensitive to common-Pb correction due to high radiogenic yield (average 98.2% radiogenic 206Pb corrected using 207Pb). Following analysis of zircon surfaces, the mount was polished to expose the interior of FCT zircons and reanalyzed. 230Th-corrected 206Pb-238U ages for FCT zircon interiors range from 28.0 to 29.5 Ma, with a weighted mean age of 28.68×0.15 Ma (2σ, n=54, MSWD=2.6, Th/Urock=2.2). Using an age of 418.4 Ma for Temora-2 (Mattinson, 2010) increases the ages for FCT zircon by 0.10 My. Despite this added uncertainty in standardization and the imprecision

  14. Algal Accessory Pigment Detection Using AVIRIS Image-Derived Spectral Radiance Data

    NASA Technical Reports Server (NTRS)

    Richardson, Laurie L.; Ambrosia, Vincent G.

    1996-01-01

    Visual and derivative analyses of AVIRIS spectral data can be used to detect algal accessory pigments in aquatic communities. This capability extends the use of remote sensing for the study of aquatic ecosystems by allowing detection of taxonomically significant pigment signatures which yield information about the type of algae present. Such information allows remote sensing-based assessment of aquatic ecosystem health, as in the detection of nuisance blooms of cyanobacteria or toxic blooms of dinoflagellates. Remote sensing of aquatic systems has traditionally focused on quantification of chlorophyll a, a photoreactive (and light-harvesting) pigment which is common to all algae as well as cyanobacteria (bluegreen algae). Due to the ubiquitousness of this pigment within algae, chl a is routinely measured to estimate algal biomass both during ground-truthing and using various airborne or satellite based sensors, including AVIRIS. Within the remote sensing and aquatic sciences communities, ongoing research has been performed to detect algal accessory pigments for assessment of algal population composition. This research is based on the fact that many algal accessory pigments are taxonomically significant, and all are spectrally unique. Aquatic scientists have been refining pigment analysis techniques, primarily high performance liquid chromatography, or HPLC, to detect specific pigments as a time-saving alternative to individual algal cell identifications and counts. Remote sensing scientists are investigating the use of pigment signatures to construct pigment libraries analogous to mineral spectral libraries used in geological remote sensing applications. The accessory pigment approach has been used successfully in remote sensing using data from the Thematic Mapper, low-altitude, multiple channel scanners, field spectroradiometers and the AVIRIS hyperspectral scanner. Due to spectral and spatial resolution capabilities, AVIRIS is the sensor of choice for such

  15. Geochemical signatures and magmatic stability of terrestrial impact produced zircon

    NASA Astrophysics Data System (ADS)

    Wielicki, Matthew M.; Harrison, T. Mark; Schmitt, Axel K.

    2012-03-01

    Understanding the role of impacts on early Earth has major implications to near surface conditions, but the apparent lack of preserved terrestrial craters > 2 Ga does not allow a direct sampling of such events. Ion microprobe U-Pb ages, REE abundances and Ti-in-zircon thermometry for impact produced zircon are reported here. These results from terrestrial impactites, ranging in age from ~ 35 Ma to ~ 2 Ga, are compared with the detrital Hadean zircon population from Western Australia. Such comparisons may provide the only terrestrial constraints on the role of impacts during the Hadean and early Archean, a time predicted to have a high bolide flux. Ti-in-zircon thermometry indicates an average of 773 °C for impact-produced zircon, ~ 100 °C higher than the average for Hadean zircon crystals. The agreement between whole-rock based zircon saturation temperatures for impactites and Ti-in-zircon thermometry (at aTiO2 = 1) implies that Ti-in-zircon thermometry record actual crystallization temperatures for impact melts. Zircon saturation modeling of Archean crustal rock compositions undergoing thermal excursions associated with the Late Heavy Bombardment predicts equally high zircon crystallization temperatures. The lack of such thermal signatures in the Hadean zircon record implies that impacts were not a dominant mechanism of producing the preserved Hadean detrital zircon record.

  16. Is there really carbon in the detrital zircons from Jack Hills, Western Australia?

    NASA Astrophysics Data System (ADS)

    Menneken, Martina; Geisler, Thorsten; Nemchin, Alexander A.; Pollok, Kilian; Whitehouse, Martin; Pidgeon, Robert; Wilde, Simon

    2014-05-01

    . Previously, we considered it impossible to remove and insert apparently larger solid minerals through such narrow openings during the polishing process. However, newly discovered CO2 inclusions along with graphite in Jack Hill zircons indicate that diamond grains from the polishing paste likely entered into cavities that were originally filled with CO2 and coated with graphite-like carbon, generating artificial graphite-diamond composite inclusions Dobrzhinetskaya et al. (2014) Diamonds in Earth's oldest zircons from Jack Hills conglomerate, Australia, are contamination. Earth Planet. Sci. Lett., 387, 212. Menneken et al. (2007) Hadean diamonds in zircon from Jack Hills, Western Australia. Nature, 448, 917. Nemchin et al. (2008) A light carbon reservoir recorded in zircon-hosted diamond from the Jack Hills. Nature, 454, 92.

  17. Jurassic zircons from the Southwest Indian Ridge.

    PubMed

    Cheng, Hao; Zhou, Huaiyang; Yang, Qunhui; Zhang, Lingmin; Ji, Fuwu; Dick, Henry

    2016-01-01

    The existence of ancient rocks in present mid-ocean ridges have long been observed but received less attention. Here we report the discovery of zircons with both reasonably young ages of about 5 Ma and abnormally old ages of approximate 180 Ma from two evolved gabbroic rocks that were dredged from the Southwest Indian Ridge (SWIR) in the Gallieni fracture zone. U-Pb and Lu-Hf isotope analyses of zircons were made using ion probe and conventional laser abrasion directly in petrographic thin sections. Young zircons and their host oxide gabbro have positive Hf isotope compositions (εHf = +15.7-+12.4), suggesting a highly depleted mantle beneath the SWIR. The spread εHf values (from-2.3 to-4.5) of abnormally old zircons, together with the unradiogenic Nd-Hf isotope of the host quartz diorite, appears to suggest an ancient juvenile magmatism along the rifting margin of the southern Gondwana prior to the opening of the Indian Ocean. A convincing explanation for the origin of the unusually old zircons is yet to surface, however, an update of the theory of plate tectonics would be expected with continuing discovery of ancient rocks in the mid-oceanic ridges and abyssal ocean basins. PMID:27185575

  18. Jurassic zircons from the Southwest Indian Ridge.

    PubMed

    Cheng, Hao; Zhou, Huaiyang; Yang, Qunhui; Zhang, Lingmin; Ji, Fuwu; Dick, Henry

    2016-05-17

    The existence of ancient rocks in present mid-ocean ridges have long been observed but received less attention. Here we report the discovery of zircons with both reasonably young ages of about 5 Ma and abnormally old ages of approximate 180 Ma from two evolved gabbroic rocks that were dredged from the Southwest Indian Ridge (SWIR) in the Gallieni fracture zone. U-Pb and Lu-Hf isotope analyses of zircons were made using ion probe and conventional laser abrasion directly in petrographic thin sections. Young zircons and their host oxide gabbro have positive Hf isotope compositions (εHf = +15.7-+12.4), suggesting a highly depleted mantle beneath the SWIR. The spread εHf values (from-2.3 to-4.5) of abnormally old zircons, together with the unradiogenic Nd-Hf isotope of the host quartz diorite, appears to suggest an ancient juvenile magmatism along the rifting margin of the southern Gondwana prior to the opening of the Indian Ocean. A convincing explanation for the origin of the unusually old zircons is yet to surface, however, an update of the theory of plate tectonics would be expected with continuing discovery of ancient rocks in the mid-oceanic ridges and abyssal ocean basins.

  19. Jurassic zircons from the Southwest Indian Ridge

    NASA Astrophysics Data System (ADS)

    Cheng, Hao; Zhou, Huaiyang; Yang, Qunhui; Zhang, Lingmin; Ji, Fuwu; Dick, Henry

    2016-05-01

    The existence of ancient rocks in present mid-ocean ridges have long been observed but received less attention. Here we report the discovery of zircons with both reasonably young ages of about 5 Ma and abnormally old ages of approximate 180 Ma from two evolved gabbroic rocks that were dredged from the Southwest Indian Ridge (SWIR) in the Gallieni fracture zone. U–Pb and Lu–Hf isotope analyses of zircons were made using ion probe and conventional laser abrasion directly in petrographic thin sections. Young zircons and their host oxide gabbro have positive Hf isotope compositions (εHf = +15.7–+12.4), suggesting a highly depleted mantle beneath the SWIR. The spread εHf values (from‑2.3 to‑4.5) of abnormally old zircons, together with the unradiogenic Nd-Hf isotope of the host quartz diorite, appears to suggest an ancient juvenile magmatism along the rifting margin of the southern Gondwana prior to the opening of the Indian Ocean. A convincing explanation for the origin of the unusually old zircons is yet to surface, however, an update of the theory of plate tectonics would be expected with continuing discovery of ancient rocks in the mid-oceanic ridges and abyssal ocean basins.

  20. Jurassic zircons from the Southwest Indian Ridge

    PubMed Central

    Cheng, Hao; Zhou, Huaiyang; Yang, Qunhui; Zhang, Lingmin; Ji, Fuwu; Dick, Henry

    2016-01-01

    The existence of ancient rocks in present mid-ocean ridges have long been observed but received less attention. Here we report the discovery of zircons with both reasonably young ages of about 5 Ma and abnormally old ages of approximate 180 Ma from two evolved gabbroic rocks that were dredged from the Southwest Indian Ridge (SWIR) in the Gallieni fracture zone. U–Pb and Lu–Hf isotope analyses of zircons were made using ion probe and conventional laser abrasion directly in petrographic thin sections. Young zircons and their host oxide gabbro have positive Hf isotope compositions (εHf = +15.7–+12.4), suggesting a highly depleted mantle beneath the SWIR. The spread εHf values (from−2.3 to−4.5) of abnormally old zircons, together with the unradiogenic Nd-Hf isotope of the host quartz diorite, appears to suggest an ancient juvenile magmatism along the rifting margin of the southern Gondwana prior to the opening of the Indian Ocean. A convincing explanation for the origin of the unusually old zircons is yet to surface, however, an update of the theory of plate tectonics would be expected with continuing discovery of ancient rocks in the mid-oceanic ridges and abyssal ocean basins. PMID:27185575

  1. Tracking the Longevity and Evolution of the Youngest Toba Tuff Using Allanite and Zircon Chronology, Thermometry, and Chemostratigraphy

    NASA Astrophysics Data System (ADS)

    Reid, M. R.; Vazquez, J. A.

    2007-12-01

    Accessory phases are powerful repositories of information about the thermal and chemical evolution of silicic magma bodies. Allanite and zircon from the relatively youthful and chemically variable Youngest Toba Tuff (YTT) of Indonesia provide key opportunities to explore gestation of Earth's largest Quaternary eruption. The YTT is compositionally zoned from 63 to 77 wt.% SiO2 but high silica rhyolite is predominant. Chemical diversity within the YTT can be explained largely by crystal fractionation. We have previously determined that allanites entrained by the eruption began to crystallize as much as 150 k.y. before eruption of the YTT at ca. 73 ka, but most crystallized within 50 k.y. of eruption. Age ranges within individual allanites can be as large as 150 k.y. Allanites from felsic enclaves yield ages that are within tens of thousands of years before eruption, but are distinct in composition from allanites in their host pumice. Zircons, on the other hand, range in age to more than 500 k.y. before eruption, although most are within 300 k.y. of it. Rare xenocrysts of Paleocene (ca. 60 Ma) and late Proterozoic (ca. 700 Ma) age and probable antecrysts from the earlier Oldest Toba Tuff are also present. Individual zircons crystallized over ca. 30 to more than 500 k.y. intervals. Taken at face value, the wider age distribution of zircon compared to allanite could be explained by secular cooling of the magma reservoir, with zircon saturation occurring much earlier than allanite saturation. Zircon saturation temperatures, FeTi-oxides, and allanite compositions collectively suggest that most of the YTT crystallized and evolved over the temperature interval 700-800°C. Temperatures based on Ti-in-zircon geothermometry expand this range to 670- 830°C. The zircons thus appear to retain a more complete record of differentiation than the host lavas and may represent crystals retained from more mafic progenitors of and/or intrusions into the YTT as well as zircons

  2. Flow Chart for Mineral Separation from Granitic Rocks.

    ERIC Educational Resources Information Center

    Mursky, Gregory

    1987-01-01

    Provided is a flow chart for the separation and purification of major, minor, and accessory minerals from granitic rocks. With careful use of heavy liquids, and a Franz Isodynamic Magnetic Separator, it is possible to obtain mineral concentrates with a purity of 95 percent or better. (Author/RH)

  3. U-Th-Pb zircon dating of the 13.8-Ma dacite volcanic dome at Cerro Rico de Potosi, Bolivia

    USGS Publications Warehouse

    Zartman, R.E.; Cunningham, C.G.

    1995-01-01

    The temporal relationship between the extrusion of the Miocene dacite volcanic dome at Cerro Rico de Potasi, Bolivia, and the associated Ag-Sn mineralization has an important bearing on the heat and metal sources for this world class mineral deposit. The present study uses U-Th-Pb dating of sparse zircon contained in the dacite to demonstrate that, at most, only several hundred thousand years separate dome emplacement from main stage mineralization. -from Authors

  4. Fission track dating of kimberlitic zircons

    USGS Publications Warehouse

    Haggerty, S.E.; Raber, E.; Naeser, C.W.

    1983-01-01

    The only reliable method for dating kimberlites at present is the lengthy and specialized hydrothermal procedure that extracts 206Pb and 238U from low-uranium zircons. This paper describes a second successful method by fission track dating of large single-crystal zircons, 1.0-1.5 cm in dimension. The use of large crystals overcomes the limitations imposed in conventional fission track analysis which utilizes crushed fragments. Low track densities, optical track dispersion, and the random orientation of polished surfaces in the etch and irradiation cycle are effectively overcome. Fission track ages of zircons from five African kimberlites are reported, from the Kimberley Pool (90.3 ?? 6.5 m.y.), Orapa (87.4 ?? 5.7 and 92.4 ?? 6.1 m.y.), Nzega (51.1 ?? 3.8 m.y.), Koffiefontein (90.0 ?? 8.2 m.y.), and Val do Queve (133.4 ?? 11.5 m.y.). In addition we report the first radiometric ages (707.9 ?? 59.6 and 705.5 ?? 61.0 m.y.) of crustal zircons from kimberlites in northwest Liberia. The fission track ages agree well with earlier age estimates. Most of the zircons examined in this study are zoned with respect to uranium but linear correlations are established (by regression analysis) between zones of variable uranium content, and within zones of constant uranium content (by analysis of variance). Concordance between the fission track method and the U/Pb technique is established and we concluded that track fading from thermal annealing has not taken place. Kimberlitic zircons dated in this study, therefore, record the time of eruption. ?? 1983.

  5. An unusual cause of subtalar pain and instability: accessory calcaneus.

    PubMed

    Boulet, C; De Maeseneer, M; Everaert, H; Kichouh, M; De Mey, J; Shahabpour, M

    2012-01-01

    We report on a 45-yr-old male sports instructor with chronic pain and instability of the ankle. He was a recreational basketball player, but because of repeated ankle sprains and chronic subtalar pain this activity became impossible. The radiologic findings were compatible with the diagnosis of accessory calcaneus. In an initial therapeutic approach the patient was treated conservatively with taping and physical therapy, but this failed to relieve the symptoms. Next, a ligamentoplasty was performed. The instability improved, but the pain remained the same. Finally the accessory calcaneus was resected and short term follow-up was unremarkable. Accessory calcaneus is an uncommon anatomical variation that may cause subtalar pain and instability. Resection of the accessory bone may be necessary to provide relief of symptoms. Accessory calcaneus can be well demonstrated on CT, SPECT-CT, and MR. MR and nuclear medicine can indicate instability of the accessory bone by showing bone marrow edema on MR or uptake on fusion imaging.

  6. Extinct 244Pu in Ancient Zircons

    NASA Astrophysics Data System (ADS)

    Turner, Grenville; Harrison, T. Mark; Holland, Greg; Mojzsis, Stephen J.; Gilmour, Jamie

    2004-10-01

    We have found evidence, in the form of fissiogenic xenon isotopes, for in situ decay of 244Pu in individual 4.1- to 4.2-billion-year-old zircons from the Jack Hills region of Western Australia. Because of its short half-life, 82 million years, 244Pu was extinct within 600 million years of Earth's formation. Detrital zircons are the only known relics to have survived from this period, and a study of their Pu geochemistry will allow us to date ancient metamorphic events and determine the terrestrial Pu/U ratio for comparison with the solar ratio.

  7. Guatemela: preliminary zircon ages from central cordillera.

    PubMed

    Gomberg, D N; Banks, P O; McBirney, A R

    1968-10-01

    Concordia resolution of uranium-lead analyses of zircons from rocks of the Guatemalan Cordillera indicates a period of plutonism, and perhaps metamorphism, in late Paleozoic times (345 +/- 20 million years). Gneisses of the Chuacus Series yield an age of 1075 +/- 25 million years which may be either the age of a source terrain for the original sediments, or the age of principal metamorphism. Zircons from a Paleozoic granite intruding the gneisses appear to contain inherited or contaminating material acquired during the process of magma generation or emplacement, or both.

  8. U-Pb dating and composition of inclusions in zircon from ophiolitic gabbro of the Klyuchevsk massif (Middle Urals): Results and geological interpretation

    NASA Astrophysics Data System (ADS)

    Smirnov, V. N.; Ivanov, K. S.; Koroteev, V. A.; Erokhin, Yu. V.; Khiller, V. V.

    2016-06-01

    The U-Pb (SHRIMP) dating of zircon from the layered complex of ophiolitic gabbro in the Klyuchevsk massif yielded an age of 456 ± 6 Ma corresponding within the limits of error to zircon dates obtained for other petrographic varieties from this massif. The investigation of the composition of silicate inclusions in dated zircon grains revealed that they are represented by typical metamorphic minerals: albite, zoisite, and secondary amphiboles. The data indicate that zircon was crystallized during metamorphic transformations of gabbroids and its U-Pb age (Late Ordovician-Silurian) is characteristic of all rocks in the ophiolite association of the Klyuchevsk massif indicating the age of metamorphism, not their formation time.

  9. Sialolithiasis of an accessory parotid gland: an unusual case.

    PubMed

    Debnath, S C; Adhyapok, A K

    2015-09-01

    We report a rare case of sialolithiasis of an accessory parotid gland, which was located anteromedial to the masseter muscle and isolated from the main parotid gland. The calculus developed from this accessory gland, and the main gland was free of lithiasis and inflammation. To our knowledge, there is no reported case of 14 stones in an accessory parotid salivary gland. The calculus was removed through a standard incision without injury to the facial nerve or a salivary fistula. PMID:26048098

  10. The Caraguataí syenitic suite, a ca. 2.7 Ga-old alkaline magmatism (petrology, geochemistry and U-Pb zircon ages). Southern Gavião block (São Francisco Craton), Brazil

    NASA Astrophysics Data System (ADS)

    Cruz, Simone Cerqueira Pereira; Peucat, Jean-Jacques; Teixeira, Leo; Carneiro, Maurício Antônio; Marques Martins, Adriano Alberto; Santana, Jocilene dos Santos; de Souza, Jailma Santos; Barbosa, Johildo Salomão Figueiredo; Leal, Ângela Beatriz Menezes; Dantas, Elton; Pimentel, Marcio

    2012-08-01

    The Gavião Block comprises amphibolite- and granulite-facies gneisses and migmatites of tonalitic, granodioritic and granitic compositions and supracrustal sequences including volcanosedimentary layers metamorphosed up to the amphibolite facies. In the region of Abaíra-Jussiape (BA), two main igneous suites, called Caraguataí and Jussiape, are exposed in the core of an anticline. The Caraguataí suite encompasses alkali-feldspar granites, syenites and quartz syenites that contain biotite, magnetite/hematite, apatite, titanite, hastingsite/pargasite and zircon as accessory minerals that were adjusted to the amphibolite facies. White mica and epidote minerals are related to retrograde greenschist facies. These rocks were deformed in dextral to reverse-dextral shear zones, giving origin to protomylonites and augen-mesomylonites to ultramylonites. The ultramylonites have a prominent banding parallel to the main foliation of the rocks. Lithogeochemical studies revealed subalkaline to alkaline, metaluminous to peraluminous, Fe-rich protolith for instead of to these rocks associated with A2-type magmatism and partial melting of igneous continental crust. In situ U-Pb zircon dating using the Laser Ablation ICPMS method was carried out for five samples of the Caraguataí alkaline suite. The ages obtained for an isotropic syenite (SCP 1470: 2680 ± 24 Ma), a foliated syenite (SCP 2035: 2703 ± 11 Ma), a syenitic augen gneiss (SCP 2017: 2706 ± 34 Ma) and two ultramylonitic syenitic banded gneisses (SCP 1446: 2711 ± 34 Ma and SCP 1809: 2698 ± 10 Ma) fall in the same range. The average of the 62 concordant analyses obtained from the five samples allows to determine a mean 207Pb/206Pb age of 2696 ± 5 Ma (±2σ) interpreted as that of the alkaline plutonism. The geochronologic data obtained up to now have not helped to constrain an age for the metamorphism that affected the study area. The A2 type of magmatism, instead of and the TDM model ages (ca. 3.2-3.8 Ga) and the

  11. Elucidating the construction of the Austurhorn Intrusion, SE Iceland, using zircon elemental and isotopic geochemistry and geochronology

    NASA Astrophysics Data System (ADS)

    Padilla, A. J.; Miller, C. F.; Carley, T. L.; Economos, R. C.; Schmitt, A. K.; Fisher, C. M.; Hanchar, J. M.; Bindeman, I. N.; Wooden, J. L.; Sigmarsson, O.

    2013-12-01

    The Austurhorn Intrusive Complex (AIC) in SE Iceland comprises large bodies of granophyre, gabbro, and a mafic-felsic composite zone (MFCZ) that exemplifies mafic-felsic interactions common in Icelandic silicic systems. However, despite being one of Iceland's best-studied intrusions (Blake 1966; Furman et al 1992a,b; Thorarinsson & Tegner 2009), few studies have included detailed analyses of zircon, a mineral widely recognized as a valuable tracer of the history and evolution of its parental magma(s). In this study, we employ in-situ zircon elemental and isotopic (hafnium and oxygen) geochemistry, as well as U-Pb geochronology, as tools for elucidating the complex construction and magmatic evolution of Austurhorn's MFCZ. The elemental compositions of AIC zircons form a broad but coherent array partly overlapping with the zircon geochemical signature for Icelandic silicic volcanic rocks (Carley et al 2011). With some exceptions (see below), Hf concentrations are low (less than 10,000 ppm), typical of Icelandic zircon, and Ti concentrations range from 6 to 25 ppm (Ti-in-zircon temps. 730-870°C). Their δ18O values are generally well-constrained at +2.5 to +4 ‰, consistent with other Icelandic magmatic zircon (Bindeman et al 2012) and preserving evidence for partial melting of hydrothermally-altered crust as the source of silicic magmas within the Austurhorn system. Epsilon-Hf values cluster tightly at +13×1 ɛ-units, suggesting a single source for the different units of the MFCZ. The notable exceptions to the trends described above are zircons from a high-silica granophyre displaying CL-dark zones and convoluted zoning. These fall well outside the AIC geochemical arrays, primarily distinguished by high Hf (up to 24,000 ppm) and lower Ti (down to 2 ppm), far higher Hf and lower Ti than any other analyzed Icelandic zircon, and extremely low δ18O values (down to -6 ‰). We interpret these to reflect multiple episodes of partial melting and melt extraction of the

  12. Accessory sperm: a biomonitor of boar sperm fertilization capacity.

    PubMed

    Ardón, Florencia; Evert, Meike; Beyerbach, Martin; Weitze, Karl-Fritz; Waberski, Dagmar

    2005-04-15

    The number of accessory sperm found in the zona pellucida of porcine embryos was correlated to their individual quality and to the embryo quality range found within a single sow. Our goal was to determine whether accessory sperm counts provide semen evaluation with additional, useful information. Accessory sperm count was highest when only normal embryos were found in a given sow and diminished if oocytes or degenerated embryos were present (P<0.01). Within a given sow, normal embryos had higher (P<0.05) accessory sperm counts than degenerated embryos, although not when oocytes were also present. Fertilization capacity of sperm is optimal when only normal embryos are found in a given sow; this capacity is indicated by high accessory sperm counts. A decrease in fertilization capacity is reflected in diminishing accessory sperm counts. The boar had a significant effect (P<0.01) on accessory sperm count, but not on the percentage of normal embryos; this suggests that accessory sperm may be more sensitive indicators of the fertilization capacity of sperm than the percentage of normal embryos. We conclude that accessory sperm count can be used for the detection of compensable defects in sperm and is a valid parameter for assessing sperm fertilization capacity.

  13. Adenoid cystic carcinoma of the accessory parotid gland.

    PubMed

    Baklacı, Deniz; Güngör, Volkan; Özcan, Müge; Yılmaz, Yavuz Fuat; Ünal, Adnan; Çolak, Aysel

    2015-01-01

    Accessory parotid gland is a small salivary gland tissue separated from main part of parotid gland. It is located on the masseter muscle anterior to the Stensen's duct. Tumors of accessory parotid gland are rare. In this article, we report an unusual case of adenoid cystic carcinoma involving accessory parotid gland. The patient presented with a progressively growing mass in the middle portion of her cheek. She underwent a partial parotidectomy including both the superficial and accessory lobes. The histopathologic diagnosis was adenoid cystic carcinoma of cribriform type. PMID:26476520

  14. 21 CFR 884.1690 - Hysteroscope and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...) MEDICAL DEVICES OBSTETRICAL AND GYNECOLOGICAL DEVICES Obstetrical and Gynecological Diagnostic Devices... portals for electrosurgical, laser, or other power sources. Such hysteroscope accessory...

  15. Compositional and phase relations among rare earth element minerals

    NASA Technical Reports Server (NTRS)

    Burt, D. M.

    1989-01-01

    A review is presented that mainly treats minerals in which the rare-earth elements are essential constituents, e.g., bastnaesite, monazite, xenotime, aeschynite, allanite. The chemical mechanisms and limits of REE substitution in some rock-forming minerals (zircon, apatite, titanite, garnet) are also derived. Vector representation of complex coupled substitutions in selected REE-bearing minerals is examined and some comments on REE-partitioning between minerals as related to acid-based tendencies and mineral stabilities are presented. As the same or analogous coupled substitutions involving the REE occur in a wide variety of mineral structures, they are discussed together.

  16. Estimates of volume and magma input in crustal magmatic systems from zircon geochronology: the effect of modelling assumptions and system variables

    NASA Astrophysics Data System (ADS)

    Caricchi, Luca; Simpson, Guy; Schaltegger, Urs

    2016-04-01

    Magma fluxes in the Earth's crust play an important role in regulating the relationship between the frequency and magnitude of volcanic eruptions, the chemical evolution of magmatic systems and the distribution of geothermal energy and mineral resources on our planet. Therefore, quantifying magma productivity and the rate of magma transfer within the crust can provide valuable insights to characterise the long-term behaviour of volcanic systems and to unveil the link between the physical and chemical evolution of magmatic systems and their potential to generate resources. We performed thermal modelling to compute the temperature evolution of crustal magmatic intrusions with different final volumes assembled over a variety of timescales (i.e., at different magma fluxes). Using these results, we calculated synthetic populations of zircon ages assuming the number of zircons crystallising in a given time period is directly proportional to the volume of magma at temperature within the zircon crystallisation range. The statistical analysis of the calculated populations of zircon ages shows that the mode, median and standard deviation of the populations varies coherently as function of the rate of magma injection and final volume of the crustal intrusions. Therefore, the statistical properties of the population of zircon ages can add useful constraints to quantify the rate of magma injection and the final volume of magmatic intrusions. Here, we explore the effect of different ranges of zircon saturation temperature, intrusion geometry, and wall rock temperature on the calculated distributions of zircon ages. Additionally, we determine the effect of undersampling on the variability of mode, median and standards deviation of calculated populations of zircon ages to estimate the minimum number of zircon analyses necessary to obtain meaningful estimates of magma flux and final intrusion volume.

  17. Insights on crustal growth from detrital zircons in ancient glacial deposits

    NASA Astrophysics Data System (ADS)

    Gaschnig, R. M.; Rudnick, R. L.; McDonough, W. F.; Kaufman, A. J.; Vervoort, J. D.; Fisher, C. M.

    2015-12-01

    Continental ice sheets can erode vast areas and carry unsorted sediment great distances before being deposited en masse. The resulting glacial diamictites can provide important information on the integrated geologic history of continents. Detrital mineral analysis, such as U-Pb geochronological and Hf isotope geochemical characterization of zircon, is one way of interrogating this sedimentary archive, and here we apply this approach to glacial diamictites of Mesoarchean and Neoproterozoic age in southern Africa and Paleoproterozoic age in North America. Several major magmatic events between 3.3 and 2.9 Ga, most notably at 3.08 Ga are recorded in detrital zircons from several of the Mesoarchean diamictites. Hf isotopes in these zircons are almost exclusively superchondritic, indicating that these are major juvenile crust forming events. In contrast, Neoproterozoic Namibian diamictites are almost devoid of Archean zircons and record a major 1.9 Ga population with subchondritic epsilon Hf, consistent with the reworking of Neoarchean (2.5-2.7 Ga) crust. Paleoproterozoic diamictites from North America (Ontario and Wyoming) are all dominated by a common age peak at 2.7 Ga with a narrow superchondritic Hf isotopic range, consistent with a major crustal growth event at this time in North America. Major globally recognized crust forming events that occurred at 2.7 Ga and orogenic events that occurred at 1.9 Ga are recorded by these diamictites. Lack of pre-Mesoarchean U-Pb ages and the superchondritic epsilon Hf of the Neoarchean and Mesoarchean detrital zircons are suggestive of minimal emergent continental crust prior to ~3.6 Ga or reflect significant preservation and/or recycling issues for the early Earth that are not well understood.

  18. Isotope dilution analysis of Ca and Zr in apatite and zircon (U-Th)/He chronometry

    NASA Astrophysics Data System (ADS)

    Guenthner, William R.; Reiners, Peter W.; Chowdhury, Uttam

    2016-05-01

    Because radiation damage influences He diffusivity, correlations between (U-Th)/He ages and effective uranium (eU, eU = U + 0.235 × Th) concentrations of single apatite and zircon grains are important for understanding thermal histories. Here we describe a method for quantifying eU concentrations in apatite and zircon grains using isotope dilution ICP-MS measurements of Zr and Ca and stoichiometry of zircon (ZrSiO4) and apatite (Ca5(PO4)3F) to obtain grain masses. Combined with independent U and Th measurements, these yield eU concentrations not based on the traditional morphologic measurements and assumptions. Additional benefits of this method include correct identification of an apatite or zircon and volume estimates for crystal shards. In some cases, this method gives eU concentrations consistent with those calculated with the morphologic approach, but often significant differences are observed between concentrations calculated from the two methods. Differences in eU concentrations for our apatite grains are greater and less than morphology estimates, and the majority are between 0.7 and 31%. With the exception of two grains, all of our zircon grains have differences between 3 and 34% less than morphology estimates. These differences could result from incorrect grain width measurements, mischaracterized grain shape, or incorrect volume calculations of the pure mineral phase due to inclusions. These morphologic errors—combined with evidence for the accuracy of our isotope dilution method from analyses of reference materials—suggest that eU concentrations calculated from morphology may often be significantly inaccurate. Finally, we demonstrate that differences between the two measurements of eU cause age-eU correlation variations for representative thermal histories.

  19. Mineral chemistry and U-series geochronology reveal timescales of differentiation for late Pleistocene peraluminous rhyolite erupted from Hayes Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Coombs, M. L.; Vazquez, J. A.; Hayden, L. A.; Calvert, A. T.

    2014-12-01

    The Hayes River ignimbrite is a recently recognized deposit from Hayes volcano, the northernmost and easternmost volcano in the Aleutian-Alaskan arc, with unusual whole-rock composition (peraluminous rhyolite; 74.2‒75.5 wt% SiO2, 1.14 to 1.18 ASI) and phenocryst mineralogy (biotite-sanidine-plagioclase-quartz) compared to the Quaternary arc. The accessory minerals zircon, monazite [(LREE)PO4], and xenotime [(Y,HREE)PO4] are also present. We use ion microprobe 238U-230Th ages and trace-element geochemistry of unpolished rims and sectioned interiors of individual zircon and monazite grains to track differentiation of the silicic magma body. Core-to-rim zoning in zircon indicates that the parent melt became progressively enriched with U, HREEs, P, and Sc, and depleted in Th and LREEs due to monazite crystallization. Zircon (238U/232Th) values reach as high as 110 in the most differentiated rims. Monazite rims exhibit similar differentiation trends with lower LREE, higher M-HREEs, and higher U than crystal interiors, which eventually led to co-precipitation of monazite and xenotime. Monazite grains form a curved array on an activity ratio plot, with unpolished rims at the higher end. The unusual abundance of monazite, which can accommodate up to several weight percent Th, in the crystallizing assemblage significantly affected the U-Th ratio of the magma as differentiation progressed. 238U/232Th values ranges from 2.6 for early melt, represented by the whole-rock value, to 7.4 for groundmass glass. Assuming monazite fractionation alone is responsible for this change, it would take ~0.12 wt% monazite crystallization, using partition coefficients of 120 and 1000 for U and Th, respectively. This amount of monazite is consistent with that observed in the samples. An isochron for early melt and low-238U/232Th monazites yields an age of 67.0±2.8 ka, whereas one for late melt and high-238U/232Th monazites yields 42.5±0.9 ka. This younger age is indistinguishable from the

  20. Macrophages: important accessory cells for reproductive function.

    PubMed

    Cohen, P E; Nishimura, K; Zhu, L; Pollard, J W

    1999-11-01

    Macrophages are found throughout reproductive tissues. To determine their role(s), we have studied mice homozygous for a null mutation (Csfm(op)) in the gene encoding the major macrophage growth factor, colony-stimulating factor-1 (CSF-1). Both male and female Csfm(op)/Csfm(op) mice have fertility defects. Males have low sperm number and libido as a consequence of dramatically reduced circulating testosterone. Females have extended estrous cycles and poor ovulation rates. CSF-1 is the principal growth factor regulating macrophage populations in the testis, male accessory glands, ovary, and uterus. However, analyses of CSF-1 nullizygous mice suggest that the primary reproductive defect is in the development of feedback regulation of the hypothalamic-pituitary axis. Although not correlating with deficiencies of microglia populations, electrophysiological investigations indicate an impairment of neuronal responses. This suggests that microglia, under the influence of CSF-1, act to organize neuronal connectivity during development and that the absence of this function results in a perturbation of the hypothalamic-pituitary-gonadal axis. Macrophages also appear to have functions in the differentiated tissues of the reproductive system, including having a positive influence on steroidogenic cells. These data suggest that macrophages, through their trophic functions, can be considered as essential accessory cells for normal reproductive functioning.

  1. Reviewing prescription spending and accessory usage.

    PubMed

    Oxenham, Julie

    This article aims to explore the role of the stoma nurse specialist in the community and how recent initiatives within the NHS have impacted on the roles in stoma care to react to the rising prescription costs in the specialty. The article will explore how the stoma care nurse conducted her prescription reviews within her own clinical commissioning group (CCG). The findings of the reviews will be highlighted by a small case history and a mini audit that reveals that some stoma patients may be using their stoma care accessories inappropriately, which may contribute to the rise in stoma prescription spending. To prevent the incorrect use of stoma appliances it may necessitate an annual review of ostomates (individuals who have a stoma), as the author's reviews revealed that inappropriate usage was particularly commonplace when a patient may have not been reviewed by a stoma care specialist for some considerable amount of time. Initial education of the ostomate and ongoing education of how stoma products work is essential to prevent the misuse of stoma appliances, particularly accessories, as the reviews revealed that often patients were not always aware of how their products worked in practice.

  2. Elemental and Isotopic Tomography at Single-Atom-Scale in 4.0 and 2.4 Ga Zircons

    NASA Astrophysics Data System (ADS)

    Valley, J. W.; Reinhard, D. A.; Snoeyenbos, D.; Lawrence, D.; Martin, I.; Kelly, T. F.; Ushikubo, T.; Strickland, A.; Cavosie, A. J.

    2012-12-01

    Atom probe tomography can determine identity (mass/charge ratio) and 3-D position of individual atoms in minerals such as zircon. These data provide unique information for understanding the thermal history and mechanisms of mineral reaction and exchange, including radiation damage. Nine needle-shaped specimens ~100 nm in diameter (at the apex) were sampled from 2 zircons by FIB and analyzed with a local-electrode atom probe (LEAP), CAMECA LEAP 4000X HR. The LEAP uses pulsed-laser heating to field evaporate the tip of a zircon needle and accelerates the ions into a position-sensitive TOF-MS. With due care for complex isobaric interferences (molecules, multiple ionizations) and background correction, it is possible to individually identify up to 10E8 atoms/needle (36% detection efficiency) by mass/charge (MRP ~ 1000@ m/n=16Da) and position (X-Y-Z coordinates on 0.2 nm scale) (Kelly & Larson 2012). The 3-D distribution of Pb and Y differ at atom-scale in the 2 zircons. Zircon #1 (4007 Ma, Jack Hills, W. Australia, Cavosie 2005, Ushikubo et al. 2008, Bouvier et al. 2011) is homogeneous in Pb and Y. In contrast, incompatible elements, including Pb and Y, are concentrated in equant 5-10 nm dia. domains, spaced ~50 nm apart in zircon #2 (2438 Ma, Albion-Raft R-Grouse Ck core complex, Utah, Strickland et al. 2011). U is homogeneously distributed in both zircons. The analyzed domains suffered 4-8 x 10E15 α-decay events/mg due to U and Th decay and yet both zircons yield >97% concordant U-Pb ages by SIMS, suggesting annealing of radiation damage during the life of the zircons. The 207-Pb/206-Pb ratios for these nm-scale domains, as measured by LEAP, average 0.17 for the 2.4 Ga Zrc2 (3 needles) and 0.43 for the 4.0 Ga Zrc1 (5 needles). These ratios are less precise (±40% 2σ) due to ultra-small sample size, but are in excellent agreement with values measured by SIMS, 0.1684 and 0.4269, respectively. Thus Pb in both zircons is radiogenic. The Pb-Y-rich domains and lack of

  3. Detrital Zircon Record of Colorado River Incision

    NASA Astrophysics Data System (ADS)

    Kimbrough, D.; Grove, M.; Gehrels, G.; Dorsey, R.; House, K. P.; Howard, K.; Pearthree, P. A.; Spencer, J. E.; Mahoney, B.

    2007-05-01

    The Colorado River is a large, youthful, unequilibrated continental drainage system the base-level for which was established rather abruptly between 5 and 6 million years ago in conjunction with Gulf of California rifting and establishment of the modern river course through the western Grand Canyon and lower Colorado river region. New laser ablation ICPMS detrital zircon U-Pb analyses (~3000) from ~40 samples provide insight into details relating to the cause, timing and consequences of river inception. These samples encompass (1) the modern Colorado River delta, (2) major tributaries including the Green, "Grand", San Juan, Little Colorado and Gila rivers (3) late Miocene to Pliocene sediments along the lower Colorado (4) late Miocene to Pleistocene deltaic and fluvial sediments of the Imperial and Palm Spring Groups in the western Salton Trough, and (5) late Miocene- early Pliocene Bidahochi Formation of eastern Arizona. Data from the western Salton Trough and modern delta yield strata yield remarkably homogeneous age distributions that indicate there was little evolution in Colorado River sediment composition since 5.3 Ma. Detrital zircon is dominated by a mix of local southwest US cratonal basement (1.7 and 1.4 Ga) plus reworked supracrustal sequences of the Colorado Plateau that provide Neoproterozoic, 1.1 Ga, and early Paleozoic zircons. A relative paucity of Grenville-age grains in the earliest part of the delta sequence may reflect an early stage of the modern river prior to deep incision through Colorado Plateau erg deposits. The strong homogeneity of the detrital zircon record from late Miocene to the present is consistent with the `lake spillover model' for inception and integration of the modern Colorado River drainage. Abrupt integration of the lower Colorado River after 5.6 Ma is clearly recorded by detrital zircon ages from the laucustrine Bouse Formation and Bullhead alluvium aggradational package. Fluvial-laucustrine deposits of the Bidahochi

  4. Mineral evolution and Earth history

    USGS Publications Warehouse

    Bradley, Dwight C.

    2015-01-01

    The field of mineral evolution—a merger of mineralogy and Earth history—coalesced in 2008 with the first of several global syntheses by Robert Hazen and coworkers in the American Mineralogist. They showed that the cumulative abundance of mineral species has a stepwise trend with first appearances tied to various transitions in Earth history such as the end of planetary accretion at ca. 4.55 Ga and the onset of bio-mediated mineralogy at ca. >2.5 Ga. A global age distribution is best established for zircon. Observed abundance of zircon fluctuates through more than an order of magnitude during successive supercontinent cycles. The pulse of the Earth is also recorded, albeit imperfectly, by the 87Sr/86Sr composition of marine biogenic calcite; the Sr-isotopic ratio of this mineral reflects the balance of inputs of primitive strontium at mid-ocean ridges and evolved strontium that drains off the continents. A global mineral evolution database, currently in the works, will greatly facilitate the compilation and analysis of extant data and the expansion of research in mineralogy outside its traditional bounds and into more interdisciplinary realms.

  5. Possible Biosphere-Lithosphere Interactions Preserved in Igneous Zircon and Implications for Hadean Earth.

    PubMed

    Trail, Dustin; Tailby, Nicholas D; Sochko, Maggie; Ackerson, Michael R

    2015-07-01

    Granitoids are silicic rocks that make up the majority of the continental crust, but different models arise for the origins of these rocks. One classification scheme defines different granitoid types on the basis of materials involved in the melting/crystallization process. In this end-member case, granitoids may be derived from melting of a preexisting igneous rock, while other granitoids, by contrast, are formed or influenced by melting of buried sedimentary material. In the latter case, assimilated sedimentary material altered by chemical processes occurring at the near surface of Earth-including biological activity-could influence magma chemical properties. Here, we apply a redox-sensitive calibration based on the incorporation of Ce into zircon crystals found in these two rock types, termed sedimentary-type (S-type) and igneous-type (I-type) granitoids. The ∼400 Ma Lachlan Fold Belt rocks of southeastern Australia were chosen for investigation here; these rocks have been a key target used to describe and explore granitoid genesis for close to 50 years. We observe that zircons found in S-type granitoids formed under more reducing conditions than those formed from I-type granitoids from the same terrain. This observation, while reflecting 9 granitoids and 289 analyses of zircons from a region where over 400 different plutons have been identified, is consistent with the incorporation of (reduced) organic matter in the former and highlights one possible manner in which life may modify the composition of igneous minerals. The chemical properties of rocks or igneous minerals may extend the search for ancient biological activity to the earliest period of known igneous activity, which dates back to ∼4.4 billion years ago. If organic matter was incorporated into Hadean sediments that were buried and melted, then these biological remnants could imprint a chemical signature within the subsequent melt and the resulting crystal assemblage, including zircon.

  6. Possible Biosphere-Lithosphere Interactions Preserved in Igneous Zircon and Implications for Hadean Earth.

    PubMed

    Trail, Dustin; Tailby, Nicholas D; Sochko, Maggie; Ackerson, Michael R

    2015-07-01

    Granitoids are silicic rocks that make up the majority of the continental crust, but different models arise for the origins of these rocks. One classification scheme defines different granitoid types on the basis of materials involved in the melting/crystallization process. In this end-member case, granitoids may be derived from melting of a preexisting igneous rock, while other granitoids, by contrast, are formed or influenced by melting of buried sedimentary material. In the latter case, assimilated sedimentary material altered by chemical processes occurring at the near surface of Earth-including biological activity-could influence magma chemical properties. Here, we apply a redox-sensitive calibration based on the incorporation of Ce into zircon crystals found in these two rock types, termed sedimentary-type (S-type) and igneous-type (I-type) granitoids. The ∼400 Ma Lachlan Fold Belt rocks of southeastern Australia were chosen for investigation here; these rocks have been a key target used to describe and explore granitoid genesis for close to 50 years. We observe that zircons found in S-type granitoids formed under more reducing conditions than those formed from I-type granitoids from the same terrain. This observation, while reflecting 9 granitoids and 289 analyses of zircons from a region where over 400 different plutons have been identified, is consistent with the incorporation of (reduced) organic matter in the former and highlights one possible manner in which life may modify the composition of igneous minerals. The chemical properties of rocks or igneous minerals may extend the search for ancient biological activity to the earliest period of known igneous activity, which dates back to ∼4.4 billion years ago. If organic matter was incorporated into Hadean sediments that were buried and melted, then these biological remnants could imprint a chemical signature within the subsequent melt and the resulting crystal assemblage, including zircon. PMID

  7. 21 CFR 864.3600 - Microscopes and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Microscopes and accessories. 864.3600 Section 864.3600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Pathology Instrumentation and Accessories §...

  8. 21 CFR 864.3600 - Microscopes and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Microscopes and accessories. 864.3600 Section 864.3600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Pathology Instrumentation and Accessories §...

  9. 21 CFR 864.3600 - Microscopes and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Microscopes and accessories. 864.3600 Section 864.3600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Pathology Instrumentation and Accessories §...

  10. 21 CFR 864.3600 - Microscopes and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Microscopes and accessories. 864.3600 Section 864.3600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Pathology Instrumentation and Accessories §...

  11. 21 CFR 884.2700 - Intrauterine pressure monitor and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Intrauterine pressure monitor and accessories. 884... Monitoring Devices § 884.2700 Intrauterine pressure monitor and accessories. (a) Identification. An intrauterine pressure monitor is a device designed to detect and measure intrauterine and amniotic...

  12. 14 CFR 121.251 - Engine accessory section diaphragm.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Engine accessory section diaphragm. 121.251 Section 121.251 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... accessory section diaphragm. Unless equivalent protection can be shown by other means, a diaphragm...

  13. 14 CFR 125.149 - Engine accessory section diaphragm.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Engine accessory section diaphragm. 125.149... Requirements § 125.149 Engine accessory section diaphragm. Unless equivalent protection can be shown by other means, a diaphragm that complies with § 125.145 must be provided on air-cooled engines to isolate...

  14. 21 CFR 884.5350 - Contraceptive diaphragm and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Contraceptive diaphragm and accessories. 884.5350 Section 884.5350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Devices § 884.5350 Contraceptive diaphragm and accessories. (a) Identification. A contraceptive...

  15. 21 CFR 884.5350 - Contraceptive diaphragm and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Contraceptive diaphragm and accessories. 884.5350 Section 884.5350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Devices § 884.5350 Contraceptive diaphragm and accessories. (a) Identification. A contraceptive...

  16. 14 CFR 125.149 - Engine accessory section diaphragm.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Engine accessory section diaphragm. 125.149... Requirements § 125.149 Engine accessory section diaphragm. Unless equivalent protection can be shown by other means, a diaphragm that complies with § 125.145 must be provided on air-cooled engines to isolate...

  17. 14 CFR 125.149 - Engine accessory section diaphragm.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Engine accessory section diaphragm. 125.149... Requirements § 125.149 Engine accessory section diaphragm. Unless equivalent protection can be shown by other means, a diaphragm that complies with § 125.145 must be provided on air-cooled engines to isolate...

  18. 14 CFR 121.251 - Engine accessory section diaphragm.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Engine accessory section diaphragm. 121.251 Section 121.251 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... accessory section diaphragm. Unless equivalent protection can be shown by other means, a diaphragm...

  19. 21 CFR 884.5350 - Contraceptive diaphragm and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Contraceptive diaphragm and accessories. 884.5350 Section 884.5350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Devices § 884.5350 Contraceptive diaphragm and accessories. (a) Identification. A contraceptive...

  20. 21 CFR 884.5350 - Contraceptive diaphragm and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Contraceptive diaphragm and accessories. 884.5350 Section 884.5350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Devices § 884.5350 Contraceptive diaphragm and accessories. (a) Identification. A contraceptive...

  1. 14 CFR 121.251 - Engine accessory section diaphragm.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Engine accessory section diaphragm. 121.251 Section 121.251 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... accessory section diaphragm. Unless equivalent protection can be shown by other means, a diaphragm...

  2. 21 CFR 884.5350 - Contraceptive diaphragm and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Contraceptive diaphragm and accessories. 884.5350 Section 884.5350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Devices § 884.5350 Contraceptive diaphragm and accessories. (a) Identification. A contraceptive...

  3. 21 CFR 884.1690 - Hysteroscope and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Hysteroscope and accessories. 884.1690 Section 884.1690 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OBSTETRICAL AND GYNECOLOGICAL DEVICES Obstetrical and Gynecological Diagnostic Devices § 884.1690 Hysteroscope and accessories....

  4. 14 CFR 23.1437 - Accessories for multiengine airplanes.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Equipment Miscellaneous Equipment § 23.1437 Accessories for multiengine airplanes. For multiengine airplanes... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Accessories for multiengine airplanes....

  5. 14 CFR 125.149 - Engine accessory section diaphragm.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Engine accessory section diaphragm. 125.149... Requirements § 125.149 Engine accessory section diaphragm. Unless equivalent protection can be shown by other means, a diaphragm that complies with § 125.145 must be provided on air-cooled engines to isolate...

  6. 14 CFR 125.149 - Engine accessory section diaphragm.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Engine accessory section diaphragm. 125.149... Requirements § 125.149 Engine accessory section diaphragm. Unless equivalent protection can be shown by other means, a diaphragm that complies with § 125.145 must be provided on air-cooled engines to isolate...

  7. 14 CFR 23.1192 - Engine accessory compartment diaphragm.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Engine accessory compartment diaphragm. 23... Powerplant Powerplant Fire Protection § 23.1192 Engine accessory compartment diaphragm. For aircooled radial engines, the engine power section and all portions of the exhaust sytem must be isolated from the...

  8. 46 CFR 98.25-40 - Valves, fittings, and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Anhydrous Ammonia in Bulk § 98.25-40 Valves, fittings, and accessories. (a) All valves, flanges, fittings and accessory equipment shall be of a type suitable for use with anhydrous ammonia and shall be made... Engineering) of this chapter. Valves shall be fitted with noncorrosive material suitable for ammonia...

  9. 46 CFR 98.25-40 - Valves, fittings, and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Anhydrous Ammonia in Bulk § 98.25-40 Valves, fittings, and accessories. (a) All valves, flanges, fittings and accessory equipment shall be of a type suitable for use with anhydrous ammonia and shall be made... Engineering) of this chapter. Valves shall be fitted with noncorrosive material suitable for ammonia...

  10. 46 CFR 98.25-40 - Valves, fittings, and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Anhydrous Ammonia in Bulk § 98.25-40 Valves, fittings, and accessories. (a) All valves, flanges, fittings and accessory equipment shall be of a type suitable for use with anhydrous ammonia and shall be made... Engineering) of this chapter. Valves shall be fitted with noncorrosive material suitable for ammonia...

  11. 21 CFR 884.2640 - Fetal phonocardiographic monitor and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Fetal phonocardiographic monitor and accessories. 884.2640 Section 884.2640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Monitoring Devices § 884.2640 Fetal phonocardiographic monitor and accessories. (a) Identification. A...

  12. 21 CFR 884.2960 - Obstetric ultrasonic transducer and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Obstetric ultrasonic transducer and accessories. 884.2960 Section 884.2960 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Monitoring Devices § 884.2960 Obstetric ultrasonic transducer and accessories. (a) Identification....

  13. 21 CFR 884.2740 - Perinatal monitoring system and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Perinatal monitoring system and accessories. 884.2740 Section 884.2740 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Monitoring Devices § 884.2740 Perinatal monitoring system and accessories. (a) Identification. A...

  14. 21 CFR 884.2700 - Intrauterine pressure monitor and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Intrauterine pressure monitor and accessories. 884.2700 Section 884.2700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Monitoring Devices § 884.2700 Intrauterine pressure monitor and accessories. (a) Identification....

  15. Morphological characteristics of the cranial root of the accessory nerve.

    PubMed

    Liu, Hong-Fu; Won, Hyung-Sun; Chung, In-Hyuk; Kim, In-Beom; Han, Seung-Ho

    2014-11-01

    There has been the controversy surrounding the cranial root (CR) of the accessory nerve. This study was performed to clarify the morphological characteristics of the CR in the cranial cavity. Fifty sides of 25 adult cadaver heads were used. The accessory nerve was easily distinguished from the vagus nerve by the dura mater in the jugular foramen in 80% of 50 specimens. The trunk of the accessory nerve from the spinal cord penetrated the dura mater at various distances before entering the jugular foramen. In 20% of the specimens there was no dural boundary. In these cases, the uppermost cranial rootlet of the accessory nerve could be identified by removing the dura mater around the jugular foramen where it joined to the trunk of the accessory nerve at the superior vagal ganglion. The cranial rootlet was formed by union of two to four short filaments emerging from the medulla oblongata (66%) and emerged single, without filament (34%), and usually joined the trunk of the accessory nerve directly before the jugular foramen. The mean number of rootlets of the CR was 4.9 (range 2-9) above the cervicomedullary junction. The CR of the accessory nerve was composed of two to nine rootlets, which were formed by the union of two to four short filaments and joined the spinal root of the accessory nerve. The CR is morphologically distinct from the vagus nerve, confirming its existence.

  16. Simon Effect with and without Awareness of the Accessory Stimulus

    ERIC Educational Resources Information Center

    Treccani, Barbara; Umilta, Carlo; Tagliabue, Mariaelena

    2006-01-01

    The authors investigated whether a Simon effect could be observed in an accessory-stimulus Simon task when participants were unaware of the task-irrelevant accessory cue. In Experiment 1A a central visual target was accompanied by a suprathreshold visual lateral cue. A regular Simon effect (i.e., faster cue-response corresponding reaction times…

  17. 14 CFR 23.1437 - Accessories for multiengine airplanes.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Accessories for multiengine airplanes. 23... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Equipment Miscellaneous Equipment § 23.1437 Accessories for multiengine airplanes. For multiengine...

  18. 14 CFR 23.1437 - Accessories for multiengine airplanes.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Accessories for multiengine airplanes. 23... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Equipment Miscellaneous Equipment § 23.1437 Accessories for multiengine airplanes. For multiengine...

  19. 14 CFR 23.1437 - Accessories for multiengine airplanes.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Accessories for multiengine airplanes. 23... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Equipment Miscellaneous Equipment § 23.1437 Accessories for multiengine airplanes. For multiengine...

  20. 21 CFR 884.2660 - Fetal ultrasonic monitor and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Fetal ultrasonic monitor and accessories. 884.2660... Devices § 884.2660 Fetal ultrasonic monitor and accessories. (a) Identification. A fetal ultrasonic monitor is a device designed to transmit and receive ultrasonic energy into and from the pregnant...

  1. Thermoluminescence of the mineral components in granite

    SciTech Connect

    Schwartzman, R.G.; Kierstead, J.A.; Levy, P.W.

    1982-01-01

    The thermoluminescence (TL) of the minerals in Climax Stock (Nevada, USA) granite has been studied. The principal mineral constituents are plagioclase, quartz, potassium feldspar and biotite. Pyrite, sphene apatite and zircon occur at one percent or less. All exhibit TL except biotite. The TL kinetics were determined for plagioclase, quartz, potassium feldspar and pyrite. Plagioclase and potassium feldspar exhibit second order and pyrite first orker kinetics. Natural TL of quartz follows second order and artificial TL first order kinetics. However, in these four minerals unrealistic kinetic parameters are often obtained; thus more general kinetics, e.g. interactive kinetics, may apply. 8 figures.

  2. U Pb, Hf and O isotope evidence for two episodes of fluid-assisted zircon growth in marble-hosted eclogites from the Dabie orogen

    NASA Astrophysics Data System (ADS)

    Wu, Yuan-Bao; Zheng, Yong-Fei; Zhao, Zi-Fu; Gong, Bing; Liu, Xiaoming; Wu, Fu-Yuan

    2006-07-01

    A combined study of internal structure, U-Pb age, and Hf and O isotopes was carried out for metamorphic zircons from ultrahigh-pressure eclogite boudins enclosed in marbles from the Dabie orogen in China. CL imaging identifies two types of zircon that are metamorphically new growth and recrystallized domain, respectively. The metamorphic zircons have low Th and U contents with low Th/U ratios, yielding two groups of 206Pb/ 238U age at 245 ± 3 to 240 ± 2 Ma and 226 ± 4 to 223 ± 2 Ma, respectively. Anomalously high δ 18O values were obtained for refractory minerals, with 9.9 to 21.4‰ for garnet and 16.9‰ for zircon. This indicates that eclogite protolith is sedimentary rocks capable of liberating aqueous fluid for zircon growth during continental subduction-zone metamorphism. Most of the zircons are characterized by very low 176Lu/ 177Hf ratios of 0.000001-0.000028, indicating their growth in association with garnet recrystallization. A few of them falling within the older age group have comparatively high 176Lu/ 177Hf ratios of 0.000192-0.000383, suggesting their growth prior to the formation of garnet in the late stage of subduction. The variations in the Lu/Hf ratios for zircons can thus be used to correlate with garnet growth during eclogite-facies metamorphism. In either case, the zircons have variable ɛHf ( t) values for individual samples, suggesting that their protolith is heterogeneous in Hf isotope composition with localized fluid availability in the bulk processes of orogenic cycle. Nevertheless, a positive correlation exists between 206Pb/ 238U ages and Lu-Hf isotope ratios for the metamorphically recrystallized zircons, suggesting that eclogite-facies metamorphism in the presence of fluid has the identical effect on zircon Lu-Hf and U-Th-Pb isotopic systems. We conclude that the zircons of the older group grew in the presence of fluid during the subduction prior to the onset of peak ultrahigh-pressure metamorphism, whereas the younger zircons

  3. New insights into the provenance of Saudi Arabian Palaeozoic sandstones from heavy mineral analysis and single-grain geochemistry

    NASA Astrophysics Data System (ADS)

    Bassis, Alexander; Hinderer, Matthias; Meinhold, Guido

    2016-03-01

    Saudi Arabian Palaeozoic siliciclastics cover a stratigraphic range from the Cambrian to the Permian. They crop out along the eastern margin of the Arabian Shield and are comprised of highly mature sandstones. Their heavy mineral assemblage reflects their mineralogical maturity and is dominated by the ultra-stable phases zircon, tourmaline and rutile. Less stable accessories are apatite, staurolite and garnet. Standard heavy mineral analysis of samples from two study areas in central/northern (Tabuk area) and southern (Wajid area) Saudi Arabia reveals distinct changes in provenance. Cambrian-Ordovician sandstones are first-cycle sediments, probably sourced from the 'Pan-African' basement. The overlying Hirnantian glaciogenic deposits consist of recycled Cambrian-Ordovician material. Devonian-Permian sandstones show a significant influx of fresh basement material, as attested by an increase of meta-stable heavy minerals. Single-grain geochemical analysis of rutile and garnet has proven to be a powerful supplementary technique. Rutile varietal studies reveal distinct differences in host rock lithologies between the two study areas: the Tabuk area contains predominantly felsic rutiles, whereas the Wajid area has more mafic input. Zr-in-rutile thermometry identified granulite-facies detritus in the lower Palaeozoic of the Tabuk area and has the potential to further define source areas. The distribution patterns of garnet host rock lithologies are remarkably similar in both study areas. They are dominated by amphibolite-facies metasediments and intermediate to felsic igneous rocks. Garnets derived from granulite-facies metasediments, which are scarce in the Arabian-Nubian Shield, also occur. Possible source rocks for high-grade garnets can be found in Yemen or farther south in the Mozambique Belt.

  4. [Occurrence and structure of accessory adrenal glands in Wistar rats].

    PubMed

    Schwabedal, P E; Partenheimer, U

    1983-01-01

    In complete series of histological sections through the entire abdomen of one normal Wistar-rat, one untreated and two bilaterally adrenalectomized, spontaneously hypertensive Wistar-rats accessory suprarenal glands were found in each case. The detailed findings in the various groups of animals investigated were as follows: (1) In the normal animal 10 accessory suprarenal glands were present. They consisted of tiny aggregates of cortical cells and were surrounded by a thin layer of collageneous fibers. The diameters of the accessory suprarenal complexes were in the order of 0.3 mm. (2) In the untreated, spontaneously hypertensive rat three accessory suprarenal glands were found. However, in contrast to what was seen in the normal rat, these complexes were larger and had diameters of up to 1 mm. Some of these accessory suprarenal glands consisted almost exclusively of small, chromophobe cells, whereas in others a rim of such cells was seen to surround a central core of larger and more acidophile cortical cells. There were few and collapsed capillaries. (3) In the bilaterally adrenalectomized, spontaneously hypertensive rats three, respectively four, accessory suprarenal glands were found. They were situated in the retroperitoneum and partly within the adipose capsule of the kidney but never in the place of the exstirpated main suprarenal glands. In one case an accessory gland was found within the fibrous capsule of the kidney and seen to compress the renal parenchyma. In the bilaterally adrenalectomized animals the average diameters of the accessory glands were larger than in the other groups reaching values of up to 5 mm. At least in both animals one of the accessory glands had a diameter comparable to that of the normal suprarenal gland of an untreated animal. The capillaries were dilated and their number was increased in comparison to what was seen in the other groups. In certain regions the cortical tissue of the accessory glands had an appearance resembling

  5. Abundance and distribution of uranium and thorium in zircon, sphene, apatite, epidote, and monazite in granitic rocks

    USGS Publications Warehouse

    Hurley, Patrick M.; Fairbairn, Harold W.

    1956-01-01

    Analyses were made of uranium and thorium in ziircon, sphene, apatite, epidote, and monazite separated as accessory minerals from samples of granitic rock from widely scattered localities to indicate the abundance and distribution of these two elements among the five mineral phases.  For any pair of mineral phases the distribution ratio remains within the same order of magnitude over the different rocks tested, although the variability of the data is such that only wide departures from constancy could be ascertained.  Such gross differences have not been found. 

  6. Provenance of Pleistocene Rhine River Middle Terrace sands between the Swiss-German border and Cologne based on U-Pb detrital zircon ages

    NASA Astrophysics Data System (ADS)

    Krippner, Anne; Bahlburg, Heinrich

    2013-04-01

    Detrital zircon U-Pb age distributions derived from samples representing ancient or relatively young large-scale continental drainage networks are commonly taken to reflect the geochronological evolution of the tapped continental area. Here, we present detrital zircon U-Pb ages and associated heavy mineral data from Pleistocene Rhine River Middle Terrace sands and equivalents between the Swiss-German border and Cologne in order to test the commonly assumed Alpine provenance of the material. Samples from eight localities were analyzed for their heavy mineral assemblages. Detrital zircon U-Pb ages were determined by laser ablation inductively coupled mass spectrometry on selected samples from five locations along the Rhine River. The zircon age populations of all samples show a similar distribution, their main peaks being between 300 and 500 Ma. Minor age populations are recognized at 570 and 1,070 Ma. The 300-400 Ma maximum reflects the Variscan basement drained by or recycled into the Rhine River and its tributaries. The 400-500 Ma peak with predominantly Early Silurian ages points to Baltica or to the mid-German crystalline rise as original sources. One distinct peak at c. 570 Ma probably represents input from Cadomian terranes. The Precambrian U-Pb ages are compatible with derivation from sources in Baltica and in northern Gondwana. The heavy mineral populations of Middle Terrace sands and equivalents are characterized to a variable extend by garnet, epidote, and green hornblende. This association is often referred to as the Alpine spectrum and is considered to be indicative of an Alpine provenance. However, hornblende, epidote, and garnet are dominant heavy minerals of collisional orogens in general and may also be derived from Variscan and Caledonian units or from intermittent storage units. A remarkable feature of the detrital zircon age distribution in the Rhine River sediments from the Swiss-German border to Cologne is the absence of ages younger than 200 Ma

  7. Fluid assisted installation of electrical cable accessories

    DOEpatents

    Mayer, Robert W.; Silva, Frank A.

    1977-01-01

    An electrical cable accessory includes a generally tubular member of elastomeric material which is to be installed by placement over a cylindrical surface to grip the cylindrical surface, when in appropriate assembled relation therewith, with a predetermined gripping force established by dilation of the tubular member, the installation being facilitated by introducing fluid under pressure, through means provided in the tubular member, between the tubular member and the cylindrical surface, and simultaneously impeding the escape of the fluid under pressure from between the tubular member and the cylindrical surface by means adjacent one of the ends of the tubular member to cause dilation of the tubular member and establish a fluid layer between the tubular member and the cylindrical surface, thereby reducing the gripping force during installation.

  8. Ostensible oncocytoma of accessory lacrimal glands.

    PubMed

    Pecorella, I; Garner, A

    1997-03-01

    Benign oncocytomas of the accessory lacrimal glands can be found in the lacrimal caruncle, plica semilunaris or conjunctival fornices, but are extremely rare. A series of 15 supposed oncocytomas of the ocular adnexa was reviewed retrospectively, and histological differences were noted with respect to the parotid gland counterpart. Lesions could be divided into three histological groups: (1) tumours composed of tubules lined by tall columnar epithelium with finely granular cytoplasm; the tubules often had dilated lumens containing mucinous secretion; (2) cystic tumours with prominent epithelial tufts projecting from much of the cyst wall; (3) tumours with solid areas composed of variably cuboidal or polygonal cells, largely in trabecular arrangement, and co-existing with the previously described tubular and cystic elements. A striking resemblance to Warthin's tumour without a lymphocytic component, such as may affect the parotid salivary gland, was noted in several tumours.

  9. Hadean Crustal Processes Revealed from Oxygen Isotopes and U-Th-Pb Depth Profiling of Pre-4.0 Ga Detrital Zircons from Western Australia

    NASA Technical Reports Server (NTRS)

    Trail, D.; Mojzsis, S. J.; Harrison, T. M.

    2005-01-01

    Because physical and chemical processes of the past are determined from analysis of a preserved geologic record, little is known about terrestrial crustal processes of the first 500 Ma during the so-called Hadean Eon. What is known from direct measurements has been derived almost exclusively from the study of greater than 4.0 Ga detrital zircons from the Jack Hills, Western Australia. The geochemistry of these zircons has direct application to understanding the origin and evolution of the rocks during the Hadean because: (i) U-Th-Pb age determinations by ion microprobe suggests the presence of crust as early as 4.37 Ga, or shortly after lunar formation; (ii) high-resolution U-Th-Pb zircon depth profiles reported here reveal several episodes of zircon growth in the Hadean previously unrecognized; (iii) core regions of pre-4.0 Ga zircons with igneous compositions are enriched in O-18 and contain metaluminous and peraluminous mineral inclusions, both features indicative of S-type grainitod protoliths. Study of these ancient zircons provides a unique window into the first half billion years that permits assessment of the potential of the Hadean Earth to host an emergent biosphere.

  10. The crystallization age of eucrite zircon.

    PubMed

    Srinivasan, G; Whitehouse, M J; Weber, I; Yamaguchi, A

    2007-07-20

    Eucrites are a group of meteorites that represent the first planetary igneous activity following metal-silicate differentiation on an early planetesimal, similar to Asteroid 4 Vesta, and, thus, help date geophysical processes occurring on such bodies in the early solar system. Using the short-lived radionuclide (182)Hf as a relative chronometer, we demonstrate that eucrite zircon crystallized quickly within 6.8 million years of metal-silicate differentiation. This implies that mantle differentiation on the eucrite parent body occurred during a period when internal heat from the decay of (26)Al and (60)Fe was still available. Later metamorphism of eucrites took place at least 8.9 million years after the zircons crystallized and was likely caused by heating from impacts, or by burial under hot material excavated by impacts, rather than from lava flows. Thus, the timing of eucrite formation and of mantle differentiation is constrained. PMID:17641194

  11. Ion microprobe U-Th-Pb geochronology and study of micro-inclusions in zircon from the Himalayan high- and ultrahigh-pressure eclogites, Kaghan Valley of Pakistan

    NASA Astrophysics Data System (ADS)

    Rehman, Hafiz Ur; Kobayash, Katsura; Tsujimori, Tatsuki; Ota, Tsutomu; Yamamoto, Hiroshi; Nakamura, Eizo; Kaneko, Yoshiyuki; Khan, Tahseenullah; Terabayashi, Masaru; Yoshida, Kenta; Hirajima, Takao

    2013-02-01

    We report ion microprobe U-Th-Pb geochronology of in situ zircon from the Himalayan high- and ultrahigh-pressure eclogites, Kaghan Valley of Pakistan. Combined with the textural features, mineral inclusions, cathodoluminescence image information and the U-Th-Pb isotope geochronology, two types of zircons were recognized in Group I and II eclogites. Zircons in Group I eclogites are of considerably large size (>100 μm up to 500 μm). A few grains are euhederal and prismatic, show oscillatory zoning with distinct core-rim luminescence pattern. Several other grains show irregular morphology, mitamictization, embayment and boundary truncations. They contain micro-inclusions such as muscovite, biotite, quartz and albite. Core or middle portions of zircons from Group I eclogites yielded concordant U-Th-Pb age of 267.6 ± 2.4 Ma (MSWD = 8.5), have higher U and Th contents with a Th/U ratio > 1, indicating typical magmatic core domains. Middle and rim or outer portions of these zircons contain inclusions of garnet, omphacite, phengite and these portions show no clear zonation. They yielded discordant values ranging between 210 and 71 Ma, indicating several thermal or Pb-loss events during their growth and recrystalization prior to or during the Himalayan eclogite-facies metamorphism. Zircons in Group II eclogites are smaller in size, prismatic to oval, display patchy or sector zoning and contain abundant inclusions of garnet, omphacite, phengite, quartz, rutile and carbonates. They yielded concordant U-Th-Pb age of 44.9 ± 1.2 Ma (MSWD = 4.9). The lower U and Th contents and a lower Th/U ratio (<0.05) in these zircons suggest their formation from the recrystallization of the older zircons during the Himalayan high and ultrahigh-pressure eclogite-facies metamorphism.

  12. Proterozoic events recorded in quartzite cobbles at Jack Hills, Western Australia: New constraints on sedimentation and source of > 4 Ga zircons

    NASA Astrophysics Data System (ADS)

    Grange, Marion L.; Wilde, Simon A.; Nemchin, Alexander A.; Pidgeon, Robert T.

    2010-03-01

    Rare heavy mineral bands within quartzite cobbles were identified in two conglomerate units within the Jack Hills belt, Western Australia. Seven zircon-bearing cobbles were analysed from one location (site 152) and three from another (site 154), both approximately 1 km west of the site where zircons in excess of 4 Ga are abundant (W74 'discovery' site). Individual pebbles from the 152 site reveal three distinctive features, containing either zircons > 3.0 Ga in age, < 1.9 Ga in age or a range of ages from ˜ 1.2 to ˜ 3.6 Ga. Those from site 154 are more uniform, containing only zircons with ages between 3.1 and 3.9 Ga. Only one grain > 4 Ga was discovered from the entire suite of pebbles, in contrast to the well-studied W74 site. A single detrital zircon with an age of 1220 ± 42 Ma from location 152 is the youngest grain so far reported from sedimentary rocks at Jack Hills. It shows magmatic oscillatory zoning and thus implies at least two sedimentary cycles within the Proterozoic; requiring erosion of an igneous precursor, incorporation into a clastic sediment, induration and subsequent erosion and transport to be hosted in the conglomerate. The nearest source for rocks of this age is the Bangemall Supergroup in the Collier Basin, ˜ 100 km northeast in the Capricorn Orogen. This would imply tectonic interleaving of originally more extensive Bangemall rocks, possibly related to activity along the Cargarah Shear Zone that traverses the Jack Hills belt. The lack of > 4.1 Ga zircons in the pebbles is highly significant, suggesting the immediate source of ancient zircons was no longer present at the Earth's surface. This equates with a general lack of ancient crystals noted in rocks that contain Proterozoic zircons from previous studies and implies that such grains diminish in number as earlier sedimentary rocks were successively recycled.

  13. Radiation Damage Study in Natural Zircon Using Neutrons Irradiation

    SciTech Connect

    Lwin, Maung Tin Moe; Amin, Yusoff Mohd.; Kassim, Hasan Abu; Mohamed, Abdul Aziz; Karim, Julia Abdul

    2011-03-30

    Changes of atomic displacements in crystalline structure of natural zircon (ZrSiO{sub 4}) can be studied by using neutron irradiation on the surface of zircon and compared the data from XRD measurements before and after irradiation. The results of neutron irradiation on natural zircon using Pneumatic Transfer System (PTS) at PUSPATI TRIGA Research Reactor in the Malaysian Nuclear Agency are discussed in this work. The reactor produces maximum thermal power output of 1 MWatt and the neutron flux of up to 1x10{sup 13} ncm{sup -2}s{sup -1}. From serial decay processes of uranium and thorium radionuclides in zircon crystalline structure, the emission of alpha particles can produce damage in terms of atomic displacements in zircon. Hence, zircon has been extensively studied as a possible candidate for immobilization of fission products and actinides.

  14. Surface chemistry and flotation behavior of monazite, apatite, ilmenite, quartz, rutile, and zircon using octanohydroxamic acid collector

    NASA Astrophysics Data System (ADS)

    Nduwa Mushidi, Josue

    Global increase in rare earth demand and consumption has led to further understanding their beneficiation and recovery. Monazite is the second most important rare earth mineral that can be further exploited. In this study, the surface chemistry of monazite in terms of zeta potential, adsorption density, and flotation response by microflotation using octanohydroxamic acid is determined. Apatite, ilmenite, quartz, rutile, and zircon are minerals that frequently occur with monazite among other minerals. Hence they were chosen as gangue minerals in this study. The Iso Electric Point (IEP) of monazite, apatite, ilmenite, quartz, rutile, and zircon are 5.3, 8.7, 3.8, 3.4, 6.3, and 5.1 respectively. The thermodynamic parameters of adsorption were also evaluated. Ilmenite, rutile and zircon have high driving forces for adsorption with DeltaGads. = 20.48, 22.10, and 22.4 kJ/mol respectively. The free energy of adsorption is 14.87 kJ/mol for monazite. Adsorption density testing shows that octanohydroxamic acid adsorbs on negatively charged surfaces of monazite and its gangue minerals which indicates chemisorption. This observation was further confirmed by microflotation experiments. Increasing the temperature to 80°C raises the adsorption and flotability of monazite and gangue minerals. This does not allow for effective separation. Sodium silicate appeared to be most effective to depress associated gangue minerals. Finally, the fundamentals learned were applied to the flotation of monazite ore from Mt. Weld. However, these results showed no selectivity due to the presence of goethite as fine particles and due to a low degree of liberation of monazite in the ore sample.

  15. Accessory bands of the hamstring tendons: A clinical anatomical study.

    PubMed

    Yasin, M N; Charalambous, C P; Mills, S P; Phaltankar, P M

    2010-10-01

    Gracilis and semitendinosus tendons are commonly used as grafts in ligamentous reconstruction. Awareness of accessory bands of these tendons is essential in preventing inadvertent diversion of the tendon harvester into the main tendon resulting in premature tendon amputation and inadequate tendon graft. The aim of this study was to describe the characteristics of these accessory bands. Twenty five patients undergoing arthroscopic anterior cruciate ligament reconstruction using hamstring tendons were included. The number of accessory bands and distance of the most proximal band from the distal periosteal insertion point on the tibial crest was recorded for both gracilis and semitendinosus. In most cases gracilis had two accessory bands; the average distance of the most proximal band from the tibial crest insertion being 5.1 cm. Semitendinosus had three bands in most cases, the average distance of the most proximal band from the tibial crest insertion being 8.1 cm. Five (20%) semitendinosus but no gracilis tendons had an accessory band originating greater than 10 cm from the tibial crest insertion. Semitendinosus had more accessory bands compared to gracilis. A significant proportion (20%) of semitendinosus and none of the gracilis tendons had bands originating greater than 10 cm proximal to the tibial crest insertion. This knowledge about the accessory bands of the hamstrings can guide toward safe harvesting of these tendons.

  16. U-Pb dating of large zircons in low-temperature jadeitite from the Osayama serpentinite melange, southwest Japan: insights into the timing of serpentinization

    USGS Publications Warehouse

    Tsujimori, T.; Liou, J.G.; Wooden, J.; Miyamoto, T.

    2005-01-01

    Crystals of zircon up to 3 mm in length occur in jadeitite veins in the Osayama serpentinite mélange, Southwest Japan. The zircon porphyroblasts show pronounced zoning, and are characterized by both low Th/U ratios (0.2-0.8) and low Th and U abundances (Th = 1-81 ppm; U = 6-149 ppm). They contain inclusions of high-pressure minerals, including jadeite and rutile; such an occurrence indicates that the zircon crystallized during subduction-zone metamorphism. Phase equilibria and the existing fluid-inclusion data constrain P-T conditions to P > 1.2 GPa at T > 350°C for formation of the jadeitite. Most U/Pb ages obtained by SHRIMP-RG are concordant, with a weighted mean 206Pb/238U age of 472 ± 8.5 Ma (MSWD = 2.7, n = 25). Because zircon porphyroblasts contain inclusions of high-pressure minerals, the SHRIMP U-Pb age represents the timing of jadeitite formation, i.e., the timing of interaction between alkaline fluid and ultramafic rocks in a subduction zone. Although this dating does not provide a direct time constraint for serpentinization, U-Pb ages of zircon in jadeitite associated with serpentinite result in new insights into the timing of fluid-rock interaction of ultramafic rocks at a subduction zone and the minimum age for serpentinization.

  17. An evaluation of the zircon method of isotopic dating in the Southern Arabian Craton

    USGS Publications Warehouse

    Cooper, J.A.; Stacey, J.S.; Stoeser, D.G.; Fleck, R.J.

    1979-01-01

    A zircon study has been made on eleven samples of igneous rocks from the Saudi Arabian Craton. Ages of sized and magnetic fractions of zircon concentrates show variable degrees of discordance which seem to result from a very young disturbance that produces linear arrays in the Concordia plot. Model age calculations based on a statistically and geologically reasonable lower intercept produce very consistent internal relationships. The Pan African Orogeny, considered to be responsible for loss of radiogenic argon and strontium from minerals of many rocks, does not appear to have affected the zircon data, even though uplift had exposed the rocks of the Arabian Shield at that time. Tonalite, granodiorite, and crosscutting leucoadamellite bodies in the southern part of the An Nimas Bathylith yield ages in the time range 820-760 Ma. A narrow time range of 660 to 665 million years was indicated for ages of widely separated and compositionally different intrusive bodies all to the east of the An Nimas Bathylith. This work suggests that the younger end of the age spectrum established from regional K-Ar and Rb-Sr measurements may be underestimated, and that magmatic activity could be more episodic than previously assumed.

  18. Sonography of the accessory head of the biceps brachii.

    PubMed

    Lutterbach-Penna, Ricardo Augusto; Brigido, Monica Kalume; Robertson, Brian; Kim, Sung Moon; Jacobson, Jon A; Fessell, David P

    2014-10-01

    Anatomic variations in the anterior aspect of the shoulder, such as an accessory head of the biceps brachii muscle, are not uncommon. The magnetic resonance imaging and arthroscopic appearance of the accessory head of the biceps brachii has been recently described. This series demonstrates the sonographic appearance of the accessory head of the biceps brachii in the bicipital groove. It is an asymptomatic, flat, echogenic structure with average measurements of 7.7 × 1.2 mm in cross section. Knowledge of this anatomic variant can avoid the misdiagnosis of a longitudinal split tear and improve the accuracy of sonography.

  19. Accessory spleen compromising response to splenectomy for idiopathic thrombocytopenic purpura

    SciTech Connect

    Ambriz, P.; Munoz, R.; Quintanar, E.; Sigler, L.; Aviles, A.; Pizzuto, J.

    1985-06-01

    Accessory spleens were sought in 28 patients who had undergone splenectomy for chronic idiopathic thrombocytopenic purpura (ITP), using a variety of techniques. Abdominal scintigraphy with autologous erythrocytes labeled with Tc-99m and opsonized with anit-D IgG (radioimmune method) proved to be most useful, clearly demonstrating one or more accessory spleens in 12 cases (43%). Computed tomography (CT) was also helpful. Four out of five patients demonstrated an increased platelet count following surgery, the effectiveness of which was illustrated by the radioimmune scan. Patients who have had splenectomy for chronic ITP should be scanned using radioimmune techniques and CT to determine whether an accessory spleen is present.

  20. Oxygen isotopic composition and U-Pb discordance in zircon

    USGS Publications Warehouse

    Booth, A.L.; Kolodny, Y.; Chamberlain, C.P.; McWilliams, M.; Schmitt, A.K.; Wooden, J.

    2005-01-01

    We have investigated U-Pb discordance and oxygen isotopic composition of zircon using high-spatial resolution ??18O measurement by ion microprobe. ??18O in both concordant and discordant zircon grains provides an indication of the relationship between fluid interaction and discordance. Our results suggest that three characteristics of zircon are interrelated: (1) U-Pb systematics and concomitant age discordance, (2) ??18O and the water-rock interactions implied therein, and (3) zircon texture, as revealed by cathodoluminescence and BSE imaging. A key observation is that U-Pb-disturbed zircons are often also variably depleted in 18O, but the relationship between discordance and ??18O is not systematic. ??18O values of discordant zircons are generally lighter but irregular in their distribution. Textural differences between zircon grains can be correlated with both U-Pb discordance and ??18O. Discordant grains exhibit either a recrystallized, fractured, or strongly zoned CL texture, and are characteristic of 18O depletion. We interpret this to be a result of metamictization, leading to destruction of the zircon lattice and an increased susceptibility to lead loss. Conversely, grains that are concordant have less-expressed zoning and a smoother CL texture and are enriched in 18O. From this it is apparent that various stages of water-rock interaction, as evidenced by systematic variations in ??18O, leave their imprint on both the texture and U-Pb systematics of zircon. Copyright ?? 2005 Elsevier Ltd.

  1. Role of zircon in tracing crustal growth and recycling

    NASA Technical Reports Server (NTRS)

    Compston, W.; Williams, I. S.; Armstrong, R. A.; Claoue-Long, J. C.; Kinny, P. D.; Foster, J. J.; Kroener, A.; Pidgeon, R. T.; Myers, J. S.

    1988-01-01

    Single crystal ion probe ages of zircons is discussed, which allow much better time resolution compared to other geochronological methods, although the technique is not without problems. Rocks from two areas that contain composite zircon populations, including true magmatic zircons as well as a variety of xenocrystic types are described. It is often difficult to distinguish these; xenocrystic zircons, for example, cannot always be identified on the basis of morphology alone. Additional evidence is needed before making age interpretations. Evidence is also presented of zircon growth long after the original time of crystallization, in some cases apparently at temperatures less than 300 C. The spectacular discovery of 4.1 to 4.2 Ga detrital zircons in metaquartzites from the Mount Narryer area of Western Australia is described. Similar zircons with ages as old as 4276 Ma have been found in the nearby Jack Hills area. The source areas or parent lithologies of these zircons have not yet been determined, but the author expects that they may be unrecognized or buried antecedents of the K rich Narryer gneisses. U or Th concentrations of zircon cannot be used to discriminate between felsic and mafic source rocks.

  2. Geochronology and Geochemistry of Zircons from the IODP Site U1437 in the Rear of the Izu-Bonin Volcanic Arc

    NASA Astrophysics Data System (ADS)

    Andrews, G. D.; Schmitt, A. K.; Busby, C. J.; Brown, S. R.

    2015-12-01

    Zircons recovered from International Ocean Discovery Program Expedition 350 Site U1437 (31°47.390'N, 139°01.580'E) in the Izu-Bonin arc were analyzed by SIMS to constrain their age (U/Pb geochronology) and geochemistry (trace elements, δ18O); LA-ICP-MS ɛHf analyses are pending. Seven intervals were dated successfully: six tuffs and lapilli-tuffs between 680.99 and 1722.46 m below sea floor (mbsf) and a single peperitic rhyolitic intrusion at 1388.86 - 1390.07 mbsf. Thirty-two intervals which underwent mineral separation lacked zircon, or yielded zircon much older than age expectations for U1437. Geochronology results from separated zircons confirm and extend the shipboard age model to 1360.77 mbsf where Late Miocene (Tortonian) submarine volcanic rocks (11.3 ±0.7 Ma; n = 17) were sampled. In-situ measurement of zircons associated with magnetite crystals in the rhyolite intrusion yield an age of 13.6 ±1.7 Ma (n = 9). Zircon U contents are low (typically <300 ppm), with trace element ratios characteristic of oceanic lithosphere and near-mantle δ18O values (4-6 ‰). Individual Miocene zircon crystals are difficult to distinguish by age alone from those in the drilling mud (sepiolite) used during Expedition 350; the sepiolite is quarried by IMV Nevada in the Amargosa Valley. Our analysis of thirty-three zircons from the sepiolite finds that they have a broad and varied age distribution (2 - 2033 Ma) with a prominent peak at 12-14 Ma, bimodal δ18O values (peaks at 5-5.5 and 6.5-7.5 ‰), and dominantly continental trace element signatures. Three zircons from U1437 are tentatively identified as sepiolite-derived, but a single Eocene grain (51.7 ±2.4 Ma) recovered from 1722.46 mbsf has an age unlike those in the sepiolite, and potentially is genuinely xenocrystic. The majority of U1437 zircons thus crystallized from evolved melts lacking continental characteristics, although thermal and compositional conditions conducive for zircon crystallization appear to have

  3. U-Pb zircon isotope system in mingled and mixed magmas:an example from Central Srednogorie, Bulgaria

    NASA Astrophysics Data System (ADS)

    Peytcheva, I.; von Quadt, A.

    2003-04-01

    Mingling and mixing of granitic and gabbroic magma occur often in volcanic-arc and postcollisional geodynamic environments. Good opportunities for studying the different stages of reaction of the two magmas provide the Srednogorie zone in Bulgaria -- elongated belt of intensive Late Cretaceous magmatic activity and related important Cu-Au-Mo ore-deposits. Present study concentrate on the behavior of the U-Pb-zircon isotope system in mingled and mixed magmas. Zircons are separated from plutons of southern part of Central Srednogorie. According to Ivanov et al. (2001) the plutons show characteristics of layered intrusions (Wiebe &Collins, 1998): their lower parts consist of crystal rich phase porphyry granodiorites, and the upper ones -- of felsic, crystal poor phase granites. Between these two not entirely crystallized parts sheet-like gabbro or gabbro-diorites bodies are intruded. Boshulya pluton represents the middle levels of the complex. Samples are collected from outcrops with sharp contact between gabbro and granodiorite and from mingled/mixed layers. The granodiorite contains concordant zircons, three of them determining a mean 206Pb/238U age of 84.6 ± 0.3 Ma. Abraded grains point to contamination of the Cretaceous magma with crustal material of different age -- Early Paleozoic (?) and older one. Calculated initial (87Sr/86Sr)T-90Ma ratio is 0.70577. Three types of accessory zircons are distinguished in the gabbro. Brown zircons are prevailing in the sample. They show negligible lead inheritance and lead loses and only for the concordant two grains a mean 206Pb/238U age of 82.16 ± 0.10 Ma is calculated. Milky zircons are about 25% in the sample and for 3 concordant grains a mean 206Pb/238U value of 85.0 ± 0.5 Ma is determined. Colorless sparkle zircons from the small size fractions give an upper intercept age of 442.7 ± 8.3 Ma. The e-HfT-440Ma of 0.85 to 1.20 suggest the hosting gneisses of the metamorphic fundament or the lower crust as possible source

  4. 26 CFR 48.4061(b)-3 - Rebuilt, reconditioned, or repaired parts or accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... operations rather than the manufacturing or production of rebuilt parts or accessories. The sale of a... accessories. 48.4061(b)-3 Section 48.4061(b)-3 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE..., reconditioned, or repaired parts or accessories. (a) Rebuilt parts or accessories. Rebuilding of...

  5. 26 CFR 48.4061(b)-3 - Rebuilt, reconditioned, or repaired parts or accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... operations rather than the manufacturing or production of rebuilt parts or accessories. The sale of a... accessories. 48.4061(b)-3 Section 48.4061(b)-3 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE..., reconditioned, or repaired parts or accessories. (a) Rebuilt parts or accessories. Rebuilding of...

  6. 26 CFR 48.4061(b)-3 - Rebuilt, reconditioned, or repaired parts or accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... operations rather than the manufacturing or production of rebuilt parts or accessories. The sale of a... accessories. 48.4061(b)-3 Section 48.4061(b)-3 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE..., reconditioned, or repaired parts or accessories. (a) Rebuilt parts or accessories. Rebuilding of...

  7. 26 CFR 48.4061(b)-3 - Rebuilt, reconditioned, or repaired parts or accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... operations rather than the manufacturing or production of rebuilt parts or accessories. The sale of a... accessories. 48.4061(b)-3 Section 48.4061(b)-3 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE..., reconditioned, or repaired parts or accessories. (a) Rebuilt parts or accessories. Rebuilding of...

  8. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and accessories... excessive restorative materials, such as gold, and to smooth rough surfaces from oral restorations, such...

  9. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and accessories... excessive restorative materials, such as gold, and to smooth rough surfaces from oral restorations, such...

  10. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and accessories... excessive restorative materials, such as gold, and to smooth rough surfaces from oral restorations, such...

  11. Accessory proteins for heterotrimeric G-proteins in the kidney

    PubMed Central

    Park, Frank

    2015-01-01

    Heterotrimeric G-proteins play a fundamentally important role in regulating signal transduction pathways in the kidney. Accessory proteins are being identified as direct binding partners for heterotrimeric G-protein α or βγ subunits to promote more diverse mechanisms by which G-protein signaling is controlled. In some instances, accessory proteins can modulate the signaling magnitude, localization, and duration following the activation of cell membrane-associated receptors. Alternatively, accessory proteins complexed with their G-protein α or βγ subunits can promote non-canonical models of signaling activity within the cell. In this review, we will highlight the expression profile, localization and functional importance of these newly identified accessory proteins to control the function of select G-protein subunits under normal and various disease conditions observed in the kidney. PMID:26300785

  12. 21 CFR 876.5820 - Hemodialysis system and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... system controls and monitors the dialysate circulating through the dialysate compartment of the dialyzer. (1) The extracorporeal blood system and accessories consists of tubing, pumps, pressure monitors, air...) The dialysate delivery system consists of mechanisms that monitor and control the...

  13. 21 CFR 876.5630 - Peritoneal dialysis system and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... accessories is a device that is used as an artificial kidney system for the treatment of patients with renal failure or toxemic conditions, and that consists of a peritoneal access device, an administration set...

  14. 21 CFR 876.5630 - Peritoneal dialysis system and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... accessories is a device that is used as an artificial kidney system for the treatment of patients with renal failure or toxemic conditions, and that consists of a peritoneal access device, an administration set...

  15. 21 CFR 876.5630 - Peritoneal dialysis system and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... accessories is a device that is used as an artificial kidney system for the treatment of patients with renal failure or toxemic conditions, and that consists of a peritoneal access device, an administration set...

  16. The clinical anatomy of accessory mental nerves and foramina.

    PubMed

    Iwanaga, Joe; Saga, Tsuyoshi; Tabira, Yoko; Nakamura, Moriyoshi; Kitashima, Sadaharu; Watanabe, Koichi; Kusukawa, Jingo; Yamaki, Koh-Ichi

    2015-10-01

    Since three-dimensional computed tomography was developed, many researchers have described accessory mental foramina. The anatomical and radiological findings have been discussed, but details of accessory mental nerves (AMNs) have only been researched in a small number of anatomical and clinical cases. For this article, we reviewed the literature relating to accessory mental foramina (AMFs) and nerves to clarify aspects important for clinical situations. The review showed that the distribution pattern of the AMN can differ according to the position of the accessory mental foramen, and the reported incidence of AMFs differs among observation methods. A review of clinical cases also revealed that injury to large AMF can result in paresthesia. This investigation did not reveal all aspects of AMNs and AMFs, but will be useful for diagnosis and treatment by many dentists and oral and maxillofacial surgeons.

  17. INTERIOR VIEW OF BATHROOM 2. SHOWING ORIGINAL TILE. CERAMIC ACCESSORIES, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW OF BATHROOM 2. SHOWING ORIGINAL TILE. CERAMIC ACCESSORIES, AND MARBLE THRESHOLD. VIEW FACING EAST. - Hickam Field, Officers' Housing Type G, 205 Seventh Street, Honolulu, Honolulu County, HI

  18. Testing the reliability of information extracted from ancient zircon

    NASA Astrophysics Data System (ADS)

    Kielman, Ross; Whitehouse, Martin; Nemchin, Alexander

    2015-04-01

    Studies combining zircon U-Pb chronology, trace element distribution as well as O and Hf isotope systematics are a powerful way to gain understanding of the processes shaping Earth's evolution, especially in detrital populations where constraints from the original host are missing. Such studies of the Hadean detrital zircon population abundant in sedimentary rocks in Western Australia have involved analysis of an unusually large number of individual grains, but also highlighted potential problems with the approach, only apparent when multiple analyses are obtained from individual grains. A common feature of the Hadean as well as many early Archaean zircon populations is their apparent inhomogeneity, which reduces confidence in conclusions based on studies combining chemistry and isotopic characteristics of zircon. In order to test the reliability of information extracted from early Earth zircon, we report results from one of the first in-depth multi-method study of zircon from a relatively simple early Archean magmatic rock, used as an analogue to ancient detrital zircon. The approach involves making multiple SIMS analyses in individual grains in order to be comparable to the most advanced studies of detrital zircon populations. The investigated sample is a relatively undeformed, non-migmatitic ca. 3.8 Ga tonalite collected a few kms south of the Isua Greenstone Belt, southwest Greenland. Extracted zircon grains can be combined into three different groups based on the behavior of their U-Pb systems: (i) grains that show internally consistent and concordant ages and define an average age of 3805±15 Ma, taken to be the age of the rock, (ii) grains that are distributed close to the concordia line, but with significant variability between multiple analyses, suggesting an ancient Pb loss and (iii) grains that have multiple analyses distributed along a discordia pointing towards a zero intercept, indicating geologically recent Pb-loss. This overall behavior has

  19. Alternative delivery of male accessory gland products

    PubMed Central

    2014-01-01

    To increase fertilization success, males transfer accessory gland products (Acps). Several species have evolved unconventional Acps transfer modes, meaning that Acps are transferred separately from the sperm. By surveying the sperm-free Acps transfer cases, we show that these animals have evolved a common strategy to deliver Acps: they all inject Acps directly through the partner’s body wall into the hemolymph. Our review of this mode of Acps transfer reveals another striking similarity: they all transfer sperm in packages or via the skin, which may leave little room for Acps transfer via the conventional route in seminal fluid. We synthesise the knowledge about the function, and the effects in the recipients, of the Acps found in the widely diverse taxa (including earthworms, sea slugs, terrestrial snails, scorpions and salamanders) that inject these substances. Despite the clearly independent evolution of the injection devices, these animals have evolved a common alternative strategy to get their partners to accept and/or use their sperm. Most importantly, the evolution of the injection devices for the delivery of Acps highlights how the latter are pivotal for male reproductive success and, hence, strongly influence sexual selection. PMID:24708537

  20. Rare accessory uraninite in a Sierran granite

    NASA Technical Reports Server (NTRS)

    Snetsinger, K. G.; Polkowski, G.

    1977-01-01

    One grain of uraninite was found in a single thin-section of Sierran granite. Electron and ion microprobe analysis were used to determine the composition. Since the U-Pb age calculated for the uraninite does not differ greatly from the K-Ar age of the unit in which it occurs, it is suggested that the mineral is primary and not reworked from a preexisting rock. No uraninite has been detected in heavy mineral concentrates from other rocks of the local area.

  1. Paleomagnetic measurements of Archean and Hadean zircons

    NASA Astrophysics Data System (ADS)

    Cottrell, R. D.; Tarduno, J. A.; Bono, R. K.

    2014-12-01

    The long-term history of the geodynamo can provide important constraints on core and mantle evolution. The oldest paleointensity records on extant rocks suggest a relatively strong magnetic field at 3.45 Ga (Tarduno et al., 2010). Examining an even older magnetic field, however, must rely on igneous components (e.g. zircons hosting magnetic inclusions) now found in younger sedimentary rocks. Here we focus on methods developed to address the challenges posed by the paleointensity measurement of crystals having weak natural remanent magnetizations (NRMs). We use a small bore (6.3 mm) 2G SQUID magnetometer that currently has the highest 3-component moment resolution for measurements, and CO2 laser heating for demagnetization. Use of this 3-component system allows for the direct measurement of full vector natural remanent magnetizations and avoids the non-uniqueness inherent in scanning magnetometer approaches. To reduce sample blank size, we use 0.5 mm fused quartz sample holders. We find that some Archean to Hadean zircons of the Jack Hills (Yilgarn Craton, Western Australia) have NRMs of ca. 1-3 x 10-9 emu, within the resolution of the ultra-high moment resolution SQUID magnetometer. Thermal demagnetization data indicate most the magnetization unblocks between 550 and 580 °C, consistent with a magnetite carrier. Magnetic force microscopy suggests the presence of sub-micron single domain-like magnetic inclusions in the zircon. Thellier-Coe paleointensity data suggest the presence of a magnetic field at 3.55 Ga. We will discuss measurements and criteria to evaluate the presence/absence of an even older Paleoarchean and Hadean magnetic field, and opportunities provided by further increases in moment resolution provided by a new spin exchange relaxation-free magnetometer.

  2. Impact Crater Environments as Potential Sources of Hadean Detrital Zircons

    NASA Astrophysics Data System (ADS)

    Kenny, G. G.; Whitehouse, M. J.; Kamber, B. S.

    2016-08-01

    Here we show that contrary to previous suggestions, there is no reason to rule out impact melt sheets as major sources of Hadean detrital zircons. We then explore the potential of other impact crater-related environments in which zircons crystallise.

  3. Extinct Plutonium Geochemistry of Ancient Hadean Zircons

    NASA Astrophysics Data System (ADS)

    Turner, G.; Gilmour, J.; Crowther, S.; Busfield, A.; Mojzsis, S.; Harrison, M.

    2005-12-01

    The abundance of 244Pu in the early solar system has important implications for r-process nucleosynthesis and models of noble gas transport within the Earth's mantle. Our recent discovery(1) of xenon isotopes from the in-situ decay of 244Pu in ancient Jack Hills zircons promises to provide a new time-sensitive window on the first 500 Ma of Earth history. We have extended this initial work by the use of resonance ioniisation mass spectrometry to analyse xenon released by stepped heating from 17 individual zircons with Pb-Pb ages in the range 3.95 to 4.18 Ga. Our immediate objectives are to determine the causes of variations in the inferred Pu/U ratios and in the longer term to determine the initial Pu/U ratio of the Earth. The Pu/U ratios calculated for individual zircons may be expected to vary as a result of igneous fractionation and also from differential loss of Pu and U fission xenon in the last 4 Ga. We have studied the effects of xenon loss by irradiating the zircons with thermal neutrons to generate xenon from 235U neutron fission in order to determine U/Xe ratios and apparent ages. 131Xe/134Xe and 132Xe/134Xe ratios can be used to calculate the relative contributions from 244Pu and 238U spontaneous fission and 235U neutron fission. The measured Pu/U ratios (back calculated to 4.56 Ga on the basis of the individual Pb-Pb ages) range from zero to 0.012. The highest ratio in our initial study was 0.008 (note that the published ratio has been revised upwards on the basis of improved decay parameters for 238U spontaneous fission). Comparison of Pb-Pb and U-Xe ages indicate varying amounts of xenon loss, over 50% in some cases. While this accounts for some of the variability in the inferred Pu/U, igneous fractionation may also play a part, and we are currently attempting to investigate this by a comparison with REE abundances. Reference: (1) Turner et al. (2004) Science, 306, 89-91.

  4. Complex history of a zircon aggregate from lunar breccia 73235

    NASA Astrophysics Data System (ADS)

    Pidgeon, R. T.; Nemchin, A. A.; van Bronswijk, W.; Geisler, T.; Meyer, C.; Compston, W.; Williams, I. S.

    2007-03-01

    Results are reported of an investigation of the age and origin of the exceptional zircon aggregate in an anorthositic clast from lunar breccia 73235. Cathodoluminescence and birefringence images show that the aggregate consists of numerous angular fragments of sector zoned primary zircon in a matrix of secondary zircon with an overall texture that resembles a pseudotachylite. SIMS U-Pb analyses of the primary fragments and the matrix yielded two clearly defined ages, an age of 4.315 ± 0.015 Ga and initial Th/U ratio of 0.21-0.35 for the primary zircon and an age of 4.187 ± 0.011 Ga and Th/U of 0.04-0.17, for the secondary zircon matrix. A Raman spectroscopic study the secondary matrix zircon was undertaken to investigate its structure. Results showed that the matrix has a zircon structure but there is also evidence for the presence of an amorphous component. Implications of the structural and U-Pb age data are discussed in terms of the origin and evolution of the aggregate and the history of lunar events. It is proposed that an original single, millimetre-sized, sector zoned zircon, formed at 4.31 Ga, was subjected to a severe shock event at 4.18 Ga. This event resulted in the fracturing of the zircon, the displacement and rotation of fragments, the compression of the aggregate to a lensoid shape, and the shock reduction of zircon to sub-micron-sized and amorphous granules in crush zones in the mosaic of fractures. Volatilisation loss of Pb and the addition of U to the secondary zircon is attributed to processes activated by the extreme thermal pulse which accompanied the 4.18 Ga shock event. Shock effects are seen in some of the primary fragments but Raman spectra of the primary and secondary zircon show no evidence for pressure-induced transformation of zircon to a scheelite structure. The zircon U-Pb system has not been affected by the ca. 3.95 Ga thermal pulse that accompanied formation of the host breccia although this event has largely reset the K

  5. Petrology and textural evolution of granites associated with tin and rare-metals mineralization at the Pitinga mine, Amazonas, Brazil

    NASA Astrophysics Data System (ADS)

    Lenharo, Sara Lais Rahal; Pollard, Peter J.; Born, Helmut

    2003-01-01

    The Água Boa and Madeira igneous complexes at the Pitinga mine were emplaced into acid volcanic rocks of the Paleoproterozoic Iricoumé Group, and host major tin, rare-metal (Zr, Nb, Ta, Y, REE) and cryolite mineralization. The igneous complexes are elongate NE-SW and each is composed of three major facies that, in order of emplacement, include porphyritic and equigranular rapakivi granite and biotite granite in both igneous complexes, followed by topaz granite in the Água Boa igneous complex (ABIC) and albite granite in the Madeira igneous complex (MIC). Rapakivi, porphyritic and granophyric textures observed in the granites are interpreted to reflect multiple stages of crystallization at different pressures (depths). Decompression during ascent shifted the magmas into the plagioclase stability field, causing partial resorption of quartz, with subsequent growth at lower pressure. Fluid saturation and separation probably occurred after final emplacement at shallow levels. Temperature and pressure estimates based on phase relations and zircon concentrations range from a maximum of 930 °C and 5 kbar for the rapakivi granites to below 650 °C and 1 kbar for the peralkaline albite granite. This suggests initial crystallization of early intrusive phases at around 15 km depth, with final emplacement of more volatile-rich crystal-mush at a depth of 0.5-1 km. Accessory minerals, including zircon, thorite, monazite, columbite-tantalite, cassiterite, bastnaesite and xenotime are present in almost all facies of the Água Boa and Madeira igneous complexes, attesting to the highly evolved character of the magmas. The presence of magnetite and/or primary cassiterite indicate crystallization under oxidizing conditions above the NNO buffer. The evolutionary sequence and Nd isotope characteristics ( TDM=2.2-2.4 Ga) of the Pitinga granites are similar to those of other Proterozoic rapakivi granites. However, petrographic, geochemical and Nd isotopic data ( ɛNd initial=-2.1 to +0

  6. Micrometer-scale U-Pb age domains in eucrite zircons, impact re-setting, and the thermal history of the HED parent body

    NASA Astrophysics Data System (ADS)

    Hopkins, M. D.; Mojzsis, S. J.; Bottke, W. F.; Abramov, O.

    2015-01-01

    Meteoritic zircons are rare, but some are documented to occur in asteroidal meteorites, including those of the howardite-eucrite-diogenite (HED) achondrite clan (Rubin, A. [1997]. Meteorit. Planet. Sci. 32, 231-247). The HEDs are widely considered to originate from the Asteroid 4 Vesta. Vesta and the other large main belt asteroids record an early bombardment history. To explore this record, we describe sub-micrometer distributions of trace elements (U, Th) and 235,238U-207,206Pb ages from four zircons (>7-40 μm ∅) separated from bulk samples of the brecciated eucrite Millbillillie. Ultra-high resolution (∼100 nm) ion microprobe depth profiles reveal different zircon age domains correlative to mineral chemistry and to possible impact scenarios. Our new U-Pb zircon geochronology shows that Vesta's crust solidified within a few million years of Solar System formation (4561 ± 13 Ma), in good agreement with previous work (e.g. Carlson, R.W., Lugmair, G.W. [2000]. Timescales of planetesimal formation and differentiation based on extinct and extant radioisotopes. In: Canup, R., Righter, K. (Eds.), Origin of the Earth and Moon. University of Arizona Press, Tucson, pp. 25-44). Younger zircon age domains (ca. 4530 Ma) also record crustal processes, but these are interpreted to be exogenous because they are well after the effective extinction of 26Al (t1/2 = 0.72 Myr). An origin via impact-resetting was evaluated with a suite of analytical impact models. Output shows that if a single impactor was responsible for the ca. 4530 Ma zircon ages, it had to have been ⩾10 km in diameter and at high enough velocity (>5 km s-1) to account for the thermal field required to re-set U-Pb ages. Such an impact would have penetrated at least 10 km into Vesta's crust. Later events at ca. 4200 Ma are documented in HED apatite 235,238U-207,206Pb ages (Zhou, Q. et al. [2011]. Early basaltic volcanism and Late Heavy Bombardment on Vesta: U-Pb ages of small zircons and phosphates in

  7. Micrometer-scale U–Pb age domains in eucrite zircons, impact re-setting, and the thermal history of the HED parent body

    USGS Publications Warehouse

    Hopkins, M.D.; Mojzsis, S.J.; Bottke, W.F.; Abramov, Oleg

    2015-01-01

    Meteoritic zircons are rare, but some are documented to occur in asteroidal meteorites, including those of the howardite–eucrite–diogenite (HED) achondrite clan (Rubin, A. [1997]. Meteorit. Planet. Sci. 32, 231–247). The HEDs are widely considered to originate from the Asteroid 4 Vesta. Vesta and the other large main belt asteroids record an early bombardment history. To explore this record, we describe sub-micrometer distributions of trace elements (U, Th) and 235,238U–207,206Pb ages from four zircons (>7–40 μm ∅) separated from bulk samples of the brecciated eucrite Millbillillie. Ultra-high resolution (∼100 nm) ion microprobe depth profiles reveal different zircon age domains correlative to mineral chemistry and to possible impact scenarios. Our new U–Pb zircon geochronology shows that Vesta’s crust solidified within a few million years of Solar System formation (4561 ± 13 Ma), in good agreement with previous work (e.g. Carlson, R.W., Lugmair, G.W. [2000]. Timescales of planetesimal formation and differentiation based on extinct and extant radioisotopes. In: Canup, R., Righter, K. (Eds.), Origin of the Earth and Moon. University of Arizona Press, Tucson, pp. 25–44). Younger zircon age domains (ca. 4530 Ma) also record crustal processes, but these are interpreted to be exogenous because they are well after the effective extinction of 26Al (t1/2 = 0.72 Myr). An origin via impact-resetting was evaluated with a suite of analytical impact models. Output shows that if a single impactor was responsible for the ca. 4530 Ma zircon ages, it had to have been ⩾10 km in diameter and at high enough velocity (>5 km s−1) to account for the thermal field required to re-set U–Pb ages. Such an impact would have penetrated at least 10 km into Vesta’s crust. Later events at ca. 4200 Ma are documented in HED apatite 235,238U–207,206Pb ages (Zhou, Q. et al. [2011]. Early basaltic volcanism and Late Heavy Bombardment on Vesta: U–Pb ages of small

  8. Li diffusion and substitution in chemically diverse synthetic zircon

    NASA Astrophysics Data System (ADS)

    Trail, D.

    2015-12-01

    Li concentrations and 7Li/6Li ratios in zircon may potentially trace crustal recycling because continental and mantle-derived zircons yield distinct values (Ushikubo et al. 2008; Bouvier et al. 2012). To some extent, the usefulness of these differences may depend upon the retentively of Li in zircon. Cherniak and Watson (2010) measured relatively high diffusivities for Li; here we sought to discover the scenarios under which Li mobility might be inhibited by charge compensating cations. We conducted "in" diffusion experiments in synthetic Lu-doped (~5000 ppm), P-doped (~250 ppm), and nearly pure zircon following the procedure in Cherniak and Watson (2010). In separate experiments, Li was ion implanted at depth within polished Mud Tank zircon slabs to form a Gaussian Li concentration profile; the relaxed concentration profile was measured after heating the zircon slabs. In all experiments, which ranged from 920 to 650 oC, calculated diffusivities were in agreement with a previously established Arrhenius relationship calibrated on trace element poor Mud Tank zircon (Cherniak and Watson, 2010). We also conducted complementary LA-ICP-MS mapping on the surfaces of P- and Lu-doped synthetic zircon crystals after the Li diffusion results were obtained. This revealed heterogeneous though patterned correlation between Li+Lu in the near surface of the crystal (no strong patterns emerged for P+Li). And finally, we observed that synthetic sector-zoned zircon exhibits near step function Li concentration profiles - correlating with changes in the rare earth element concentrations across these sectors - which allowed us to examine Li diffusion in yet another manner. Re-heating these grains followed by LA-ICP-MS analysis revealed significant Li migration, with no detectable migration of the rare earth elements. While our experiments cannot be considered exhaustive, we have yet to find a scenario where Li mobility in synthetic zircon depends on charge compensating cations.

  9. Archean Arctic continental crust fingerprints revealing by zircons from Alpha Ridge bottom rocks

    NASA Astrophysics Data System (ADS)

    Sergeev, Sergey; Petrov, Oleg; Morozov, Andrey; Shevchenko, Sergey; Presnyakov, Sergey; Antonov, Anton; Belyatsky, Boris

    2015-04-01

    Whereas thick Cenozoic sedimentary cover overlapping bedrock of the Arctic Ocean, some tectonic windows were sampled by scientific submarine manipulator, as well as by grabbing, dredging and drilling during «Arctic-2012» Russian High-Arctic expedition (21 thousands samples in total, from 400-km profile along Alpha-Mendeleev Ridges). Among others, on the western slope of Alpha Ridge one 10x10 cm fragment without any tracks of glacial transportation of fine-layered migmatitic-gneiss with prominent quartz veinlets was studied. Its mineral (47.5 vol.% plagioclase + 29.6% quartz + 16.6% biotite + 6.1% orthoclase) and chemical composition (SiO2:68.2, Al2O3:14.9, Fe2O3:4.44, TiO2:0.54, MgO:2.03, CaO:3.13, Na2O:3.23, K2O:2.16%) corresponds to trachydacite vulcanite, deformed and metamorphozed under amphibolite facies. Most zircon grains (>80%) from this sample has an concordant U-Pb age 3450 Ma with Th/U 0.8-1.4 and U content of 100-400 ppm, epsilon Hf from -4 up to 0, and ca 20% - ca 3.3 Ga with Th/U 0.7-1.4 and 90-190 ppm U, epsilon Hf -6.5 to -4.5, while only 2% of the grains show Proterozoic age of ca 1.9 Ga (Th/U: 0.02-0.07, U~500 ppm, epsilon Hf about 0). No younger zircons were revealed at all. We suppose that magmatic zircon crystallized as early as 3450 Ma ago during acid volcanism, the second phase zircon crystallization from partial melt (or by volcanics remelting) under amphibolite facies metamorphism was at 3.3 Ga ago with formation of migmatitie gneisses. Last zircon formation from crustal fluids under low-grade metamorphic conditions was 1.9 Ga ago. There are two principal possibilities for the provenance of this metavolcanic rock. The first one - this is ice-rafted debris deposited by melted glacial iceberg. However, presently there are no temporal and compositional analogues of such rocks in basement geology of peri-oceanic regions, including Archean Itsaq Gneiss Complex, Lewisian Complex and Baltic Shield but these regions are far from the places of

  10. The Crystal Structure of Lanthanide Zirconates

    NASA Astrophysics Data System (ADS)

    Clements, Richard; Kennedy, Brendan; Ling, Christopher; Stampfl, Anton P. J.

    2010-03-01

    The lanthanide zirconates of composition Ln2Zr2O7 (Ln = La-Gd) are of interest for use in inert matrix fuels and nuclear wasteforms. The series undergoes a pyrochlore to fluorite phase transition as a function of the Ln atomic radii. The phase transition has been attributed to disordering of both the cation and the anion [1]. We have undertaken a synthesis of the lanthanide zirconate series Ln2Zr2O7 (Ln = La-Gd), Ln0.2Zr0.8O1.9 (Ln = Tb-Yb) and NdxHo2-xZr2O7 (0

  11. Wide excision of accessory parotid gland with anterior approach.

    PubMed

    Choi, Hwan Jun; Lee, Young Man; Kim, Jun Hyuk; Tark, Min Seong; Lee, Jang Hyun

    2012-01-01

    Accessory parotid gland tissue has been described as salivary tissue adjacent to the Stensen duct that is distinctly separate from the main body of the parotid gland. Of all parotid gland tumors, 1% to 8% arise from the accessory parotid gland. Little is known about the accessory parotid gland, and it is seldom mentioned in the literature. Between 1999 and 2010, we have treated and followed 8 patients with tumors of the accessory parotid gland. There were 5 males and 3 females with a mean age of 35 years. They all presented with an asymptomatic cheek mass, and 4 of them underwent fine-needle aspiration. Ultrasound or computed tomographic scan was used in all patients. All the patients underwent surgical intervention with standard parotidectomy incision and anterior extension. The mean follow-up time was 44 months (range, 6-120 months). Seven patients had benign disease. Four cases were pleomorphic adenoma, and the remaining 3 benign cases were parotid cyst, basal cell adenoma, and hemangioma. Only 1 patient had a malignant tumor that was a lymphoepithelioma-like carcinoma. In 7 cases, wide excision (excision of mass and accessory lobe of the parotid gland) was done because of the intra-accessory parotid gland lesion. One patient had concomitant superficial parotidectomy because the tumor was located very close to and has involved the parotid gland proper. There was no serious postoperative complication and recurrence. Prudent preoperative diagnostic evaluation and meticulous surgical approach are the keys to successful management of midcheek lesions. A wide excision of the accessory lobe of the parotid gland can be a definitive surgery in case of solitary tumor with an intact parotid fascia, and wide excision with anterior approach through a standard parotidectomy incision is preferred to a direct incision over the mass.

  12. Implications of Bishop Tuff zircon U-Pb ages for rates of zircon growth and magma accumulation

    NASA Astrophysics Data System (ADS)

    Reid, M. R.; Schmitt, A. K.

    2012-12-01

    Rates of geologic processes obtained from natural studies rely on accurate geochronologic information. An important benchmark in geochronology as well as a valuable source of insights into the evolution of voluminous explosive eruptions is the >600 km3 Bishop Tuff (BT). A recently determined weighted mean 206Pb/238U date of 767.1±0.9 ka for a BT zircon population [1] is indistinguishable from the recalibrated 40Ar/39Ar sanidine date of 767.4±2.2 ka [2], potentially providing a key intercalibration point between astronomical and radio-isotopic dating approaches. Consequences of these results are linear zircon growth rates of >1×10-14 cm/sec and magma accumulation rates of >200 km3/ka. In contrast, spatially selective SIMS U-Pb dating of BT zircons yielded mean pre-eruption ages of 850 ka [3], a difference that raises questions about the validity of intercalibration between U-Pb and K-Ar dating methods and the history of magma accumulation. We obtained new SIMS analyses of the BT zircons using more spatially and analytically sensitive methods and verifying our accuracy against the TIMS dated Quaternary zircon 61.308A (2.488±0.002 Ma). Analyses were performed on zircon rims and on oriented cross-sections exposed during optical interferometry-calibrated serial sectioning removing the outermost ~31 μm. Sputtering by a 100 nA ion beam versus the normally employed 10-12 nA beam resulted in enhanced radiogenic Pb yields and analytical uncertainties for Quaternary zircon approaching the U-Pb age reproducibility of the primary zircon standard (~1-2 % for AS3). Ages obtained at ~31 μm depth (representing <5% of crystal growth in most cases) average 892±26ka (MSWD=0.29), corroborating previous evidence for residence times of several tens of ka. Rim ages average 781±22 ka (MSWD=0.61), overlapping Ar/Ar determinations of eruption age and corroborating the importance of near-eruption aged zircon growth. Our results confirm the presence of BT zircon domains that predate

  13. Continental crustal history in SE Asia: Insights from zircon geochronology

    NASA Astrophysics Data System (ADS)

    Sevastjanova, I.; Hall, R.; Gunawan, I.; Ferdian, F.; Decker, J.

    2012-12-01

    It is well known that SE Asia is underlain mostly by continental crust derived from Gondwana. However, there are still many uncertainties about the ages of protoliths, origin, arrival ages and history of different blocks, because much of the basement is unexposed. We have compiled previously published and new zircon U-Pb age and Hf isotope data from SE Asia. Our data set currently contains over 8400 U-Pb ages and over 600 Hf isotope analyses from sedimentary, metamorphic and igneous rocks and work is continuing to increase its size and the area covered. Zircons range in age from 3.4 Ga to near-zero. Archean zircons (>2.5 Ga) are rare in SE Asia and significant Archean populations (particularly zircons >2.8 Ga) are found only in East Java and the Sibumasu block of the Malay Peninsula. The presence of Archean zircons strongly suggests that the East Java and Sibumasu blocks were once situated near present-day Western Australia. Detrital Paleoproterozoic (ca. 1.9-1.8 Ga) zircons are abundant in many parts of SE Asia. In Sundaland (Malay Peninsula, Sumatra, West Java, Borneo) the most likely source for these zircons is the tin belt basement, but a north Australian source is more likely for eastern Indonesian samples. An early Mesoproterozoic (ca. 1.6-1.5 Ga) zircon population, particularly common in eastern Indonesia, is interpreted to be derived from central or northern Australia. Mesoproterozoic zircons, ca. 1.4 Ga, are common only on fragments that are now attached to or were previously part of the north Australian margin, such as the Bird's Head of New Guinea, Timor, Seram, Sulawesi and SW Borneo. Hf isotope characteristics of zircons from Seram are similar to those of zircons from eastern Australia. This supports the suggestion that Seram was part of the Australian margin. Late Meso- and early Neoproterozoic zircons (ca. 1.2-1.1 Ga, 900 Ma, and 600 Ma) are present, but not abundant, in SE Asia. Dominant Phanerozoic populations are Permian-Triassic, Cretaceous, and

  14. Zirconia (NC) zircon as a potential standard

    NASA Astrophysics Data System (ADS)

    Covey, A. K.; Braun, S. A.; Gualda, G. A.; Bream, B. R.; Fisher, C.; Wooden, J. L.; Schmitz, M. D.

    2012-12-01

    As microanalysis continues to advance and become more widespread there is a greater need for abundant and suitable age standards. Megacrystic zircons from the inactive Freeman Mine near Zirconia, NC were collected from weathered mine dump piles. Zirconia zircon crystals are large (> 1 mm) relative to typical zircons (up to 100s μm) and easily obtained; attributes that make them attractive as a potential standard. We present here preliminary data and assess the suitability of Zirconia zircons as a U-Pb geochronology, Hf-isotope and trace-element standard. Grains are variably fluorescent (Callahan et al, Southeastern Geol., 2007), and we used shortwave fluorescence to separate grains with high, medium, low/no fluorescence from one another. Images were taken of the grains before mounting and post-polishing to understand the fluorescence characterization of the surface to the core. After preparing the grains, we found that the fluorescence was not homogenous and did not provide a good means of separating out grains. In order to investigate the differences in fluorescence, we collected cathodoluminescence (CL) and backscatter electron (BSE) images and energy dispersive spectroscopy (EDS) maps using a Tescan Vega 3 LMU equipped with an Oxford X-max 50 mm2 solid-state EDS detector at Vanderbilt University. This allowed division of the grains into two types: (a) grains with finely oscillatory zoned rims, which are variably crosscut by dull-CL irregular zones, sometimes showing hourglass zoning; and (b) grains with cores showing more irregular, patchy zoning with and without thin oscillatory rims. EDS maps show no major element zoning in the zircon grains, but reveal a variety of inclusions, particularly of quartz and thorite. Preliminary U-Pb ages were obtained using a Perkin Elmer Elan DRCII ICP-MS coupled with a New Wave/Mechantek 213 nm Nd:YAG laser ablation system at Vanderbilt University. A total of ~150 individual ages on oscillatory-zoned (Type a) crystals yield a

  15. A direct comparison of the ages of detrital monazite versus detrital zircon in Appalachian foreland basin sandstones: Searching for the record of Phanerozoic orogenic events

    NASA Astrophysics Data System (ADS)

    Hietpas, Jack; Samson, Scott; Moecher, David

    2011-10-01

    The provenance potential of detrital monazite was investigated by in situ measurement of 232Th- 208Pb dates of grains isolated from six Middle Carboniferous-Permian sandstones from the Appalachian foreland basin. Provenance assessment of these units was previously investigated by measuring U-Pb crystallization ages of detrital zircon (Thomas et al., 2004; Becker et al., 2005, 2006). Approximately 90% of the detrital zircon ages record Mesoproterozoic or older ages, with only 10% recording the three major pulses of tectonism (Taconian, Acadian and Alleghanian) that are the hallmark of the Appalachian Orogen. 232Th- 208Pb ages of detrital monazite, however, strongly record the complex phases of Paleozoic orogenesis. Nearly 65% of the ages record Paleozoic events, while 35% record Neoproterozoic or older ages. In several of the analyzed sandstones, detrital monazite ages record Paleozoic orogenic events that are completely missed by detrital zircon ages, demonstrating that monazite ages more accurately reflect the character of the sediment source rocks. The inferred maximum age of sediment deposition, as determined by the youngest monazite grains, is ~ 550 Ma younger for two of the analyzed sandstones compared to depositional constraints based on the youngest detrital zircon. The different physical properties and petrogenesis of zircon and monazite are interpreted to be factors for the dramatic differences in sediment provenance information provided by each mineral. The results from this study have important implications for determining sediment provenance, constraining maximum age of sediment deposition, and developing robust regional tectonic models.

  16. Accessory costs of seed production and the evolution of angiosperms.

    PubMed

    Lord, Janice M; Westoby, Mark

    2012-01-01

    Accessory costs of reproduction frequently equal or exceed direct investment in offspring, and can limit the evolution of small offspring sizes. Early angiosperms had minimum seed sizes, an order of magnitude smaller than their contemporaries. It has been proposed that changes to reproductive features at the base of the angiosperm clade reduced accessory costs thus removing the fitness disadvantage of small seeds. We measured accessory costs of reproduction in 25 extant gymnosperms and angiosperms, to test whether angiosperms can produce small seeds more economically than gymnosperms. Total accessory costs scaled isometrically to seed mass for angiosperms but less than isometrically for gymnosperms, so that smaller seeds were proportionally more expensive for gymnosperms to produce. In particular, costs of abortions and packaging structures were significantly higher in gymnosperms. Also, the relationship between seed:ovule ratio and seed size was negative in angiosperms but positive in gymnosperms. We argue that the carpel was a key evolutionary innovation reducing accessory costs in angiosperms by allowing sporophytic control of pre- and postzygotic mate selection and timing of resource allocation. The resulting reduction in costs of aborting unfertilized ovules or genetically inferior embryos would have lowered total reproductive costs enabling early angiosperms to evolve small seed sizes and short generation times.

  17. Refining the dating process: rare earth element analysis of zircon

    NASA Astrophysics Data System (ADS)

    Kelly, N. M.; Harley, S. L.

    2003-04-01

    The difficulty in accurately determining the timing of zircon growth, during metamorphism and relative to individual metamorphic events in polymetamorphosed rocks, can result in ambiguous interpretation of any resulting U/Pb ages. However, REE analysis combined with detailed image analysis can place better constraints on age data. In this study, three samples previously dated by Harley and Black (1997) were selected for detailed image and REE analysis. A garnet-absent charnockite from Proclamation Island contains magmatic zircon grains c.2990 Ma in age that have REE patterns typical of magmatic zircon. Low CL, c.2850 Ma mantles and rims on these grains are slightly depleted in MREE relative to magmatic zircon grains. High CL rims (yet to be dated) exhibit larger depletions in MREE compared with low CL zircon rims, and minor depletions in HREE. Altered zircon cores with ages of <2850 Ma have similar REE patterns to high CL zircon rims. A garnet-orthopyroxene-bearing granodioritic orthogneiss from Dallwitz Nunatak has c.2990 Ma magmatic zircons that retain steep REE patterns. Low CL rims on these grains have weak planar banding, and are depleted in MREE and slightly enriched in HREE relative to the magmatic zircon. These rims have ages that scatter between 2900 and 2700 Ma, with a dominant cluster at c.2840 Ma. High- to moderate CL c.2490 Ma rims have planar growth banding and sector zoning. These rims are depleted in M-HREE and have "flat" REE patterns that are similar to those from garnet and orthopyroxene in the same sample. A third sample, garnet-bearing paragneiss from Zircon Point, contains inherited magmatic zircons that have ages between 2850 and 2970 Ma, and typical magmatic REE patterns. Altered magmatic grains, ages of which scattered between 2850 and 2600 Ma, have depleted M-HREE patterns that are slightly positively sloping. Low-moderate CL grains, low CL outer rims, and mod-high CL rims, also depleted in M-HREE but all have slightly negatively sloping

  18. Interlaboratory comparison of mineral constituents in a sample from the Herrin (No. 6) coal bed from Illinois

    USGS Publications Warehouse

    Finkelman, Robert B.; Fiene, F.L.; Miller, R.N.; Simon, F.O.

    1984-01-01

    and possibly coquimbite and jarosite were also identified. Scanning electron microscopy studies indicated ubiquitous pyrite framboids and, less commonly, euhedral crystals, skeletal grains, irregularly shaped particles, and vein fillings. Minor accessory minerals such as rare-earth phosphates and possibly silicates, zircon, barium sulfate, titanium oxide, and sphalerite were also found. The textural evidence indicates that the minerals in the banded material are detrital whereas the minerals occurring as vein and pore fillings are authigenic. Magnetic measurements indicate that coal crushed in a steel pulverizer is contaminated by small quantities of abrasion fragments from the crusher, which seriously affect the measured magnetic properties of the coal.

  19. Proton conductivity of potassium doped barium zirconates

    SciTech Connect

    Xu Xiaoxiang; Tao Shanwen; Irvine, John T.S.

    2010-01-15

    Potassium doped barium zirconates have been synthesized by solid state reactions. It was found that the solubility limit of potassium on A-sites is between 5% and 10%. Introducing extra potassium leads to the formation of second phase or YSZ impurities. The water uptake of barium zirconates was increased even with 5% doping of potassium at the A-site. The sintering conditions and conductivity can be improved significantly by adding 1 wt% ZnO during material synthesis. The maximum solubility for yttrium at B-sites is around 15 at% after introducing 1 wt% zinc. The conductivity of Ba{sub 0.95}K{sub 0.05}Zr{sub 0.85}Y{sub 0.11}Zn{sub 0.04}O{sub 3-{delta}} at 600 deg. C is 2.2x10{sup -3} S/cm in wet 5% H{sub 2}. The activation energies for bulk and grain boundary are 0.29(2), 0.79(2) eV in wet 5% H{sub 2} and 0.31(1), 0.74(3) eV in dry 5% H{sub 2}. A power density of 7.7 mW/cm{sup 2} at 718 deg. C was observed when a 1 mm thick Ba{sub 0.95}K{sub 0.05}Zr{sub 0.85}Y{sub 0.11}Zn{sub 0.04}O{sub 3-{delta}} pellet was used as electrolyte and platinum electrodes. - Graphical abstract: Potassium doped barium zirconates have been synthesized by solid state reactions. It was found that the solubility limit of potassium on A-sites is between 5% and 10 %. The sintering conditions and conductivity can be improved significantly by adding 1 wt% ZnO during material synthesis. Five percent doping of potassium at A-site can double the total conductivity.

  20. Zircon megacrysts from kimberlite: oxygen isotope variability among mantle melts

    NASA Astrophysics Data System (ADS)

    Valley, John W.; Kinny, Peter D.; Schulze, Daniel J.; Spicuzza, Michael J.

    The oxygen isotope ratios of Phanerozoic zircons from kimberlite pipes in the Kaapvaal Craton of southern Africa and the Siberian Platform vary from 4.7 to 5.9‰ VSMOW. High precision, accurate analyses by laser reveal subtle pipe-to-pipe differences not previously suspected. These zircons have distinctive chemical and physical characteristics identifying them as mantle-derived megacrysts similar to zircons found associated with diamond, coesite, MARID xenoliths, Cr-diopside, K-richterite, or Mg-rich ilmenite. Several lines of evidence indicate that these 18O values are unaltered by kimberlite magmas during eruption and represent compositions preserved since crystallization in the mantle, including: U/Pb age, large crystal size, and the slow rate of oxygen exchange in non-metamict zircon. The average 18O of mantle zircons is 5.3‰, 0.1 higher and in equilibrium with values for olivine in peridotite xenoliths and oceanic basalts. Zircon megacrysts from within 250 km of Kimberley, South Africa have average 18O=5.32+/-0.17 (n=28). Small, but significant, differences among other kimberlite pipes or groups of pipes may indicate isotopically distinct reservoirs in the sub-continental lithosphere or asthenosphere, some of which are anomalous with respect to normal mantle values of 5.3+/-0.3. Precambrian zircons (2.1-2.7 Ga) from Jwaneng, Botswana have the lowest values yet measured in a mantle zircon, 18O=3.4 to 4.7‰. These zircon megacrysts originally crystallized in mafic or ultramafic rocks either through melting and metasomatism associated with kimberlite magmatism or during metamorphism. The low 18O zircons are best explained by subduction of late Archean ocean crust that exchanged with heated seawater prior to underplating as eclogite and to associated metasomatism of the mantle wedge. Smaller differences among other pipes and districts may result from variable temperatures of equilibration, mafic versus ultramafic hosts, or variable underplating. The narrow

  1. Stoma appliances and accessories: getting it right for the patient.

    PubMed

    Burch, Jennie

    This article will examine some of the appliances and accessories that can be used to care for a stoma. There are three types of stoma that can be surgically formed and each will be discussed. Furthermore, there will be brief explanations of why stomas might be formed and what the output from each stoma type will be. Complications are associated with stomas, such as sore skin, which is commonly seen within the first few months after the stoma is formed. This important topic is examined and some of the accessories that can be used to treat these issues will be explored. To aid the reader to undertake their own research on the topic, the websites from some of the stoma manufacturers are included. These websites contain more details about appliances, accessories and information for people with a stoma that can be of benefit to nurses too. PMID:25251316

  2. [Surgical treatment strategy for flatfoot related with accessory navicular].

    PubMed

    Deng, Yin-shuan; Gao, Qiu-ming; Zhen, Ping; Tang, Kang-lai

    2015-02-01

    Accessory navicular source flatfoot is one of the foot deformity of clinical common disease,its treatment method is more controversial, differences in clinical efficacy of different surgical methods, according to accessory navicular source flatfoot symptoms of surgical treatment,there is no uniform standard, around a pair of accessory navicular excision how to reconstruct the arch produced a series of operation methods, the clinical curative effect of different operative methods produce also different, how to develop the operation strategy, choose operation method, and after acessory navicular excision whether to rebuild posterior tibial tendon, how to rebuild, the problems such as how to rebuild is the research hotspot and difficulty, looking forward to further research.

  3. Case report: accessory head of the deep forearm flexors

    PubMed Central

    JONES, M.; ABRAHAMS, P. H.; SAÑUDO, J. R.

    1997-01-01

    In 1813 Gantzer described 2 accessory muscles in the human forearm which bear his name (Wood, 1868; Macalister, 1875) and these have subsequently been reported with variable attachments (Wood, 1868; Macalister, 1875; Turner, 1879; Schäfer & Thane, 1894; Le Double, 1897; Dykes & Anson, 1944; Mangini, 1960; Malhotra et al. 1982; Kida, 1988; Tountas & Bergman, 1993). The accessory heads of the deep flexors of the forearm (Gantzer's muscles) have been described as 2 different small bellies which insert either into FPL or FDP. There are no previous reports which have mentioned the existence of an accessory muscle which inserts into both of the 2 deep flexors of the forearm as in the case presented here. PMID:9306208

  4. Endocytic Accessory Factors and Regulation of Clathrin-Mediated Endocytosis

    PubMed Central

    Merrifield, Christien J.; Kaksonen, Marko

    2014-01-01

    Up to 60 different proteins are recruited to the site of clathrin-mediated endocytosis in an ordered sequence. These accessory proteins have roles during all the different stages of clathrin-mediated endocytosis. First, they participate in the initiation of the endocytic event, thereby determining when and where endocytic vesicles are made; later they are involved in the maturation of the clathrin coat, recruitment of specific cargo molecules, bending of the membrane, and finally in scission and uncoating of the nascent vesicle. In addition, many of the accessory components are involved in regulating and coupling the actin cytoskeleton to the endocytic membrane. We will discuss the different accessory components and their various roles. Most of the data comes from studies performed with cultured mammalian cells or yeast cells. The process of endocytosis is well conserved between these different organisms, but there are also many interesting differences that may shed light on the mechanistic principles of endocytosis. PMID:25280766

  5. Plutonism, deformation, and metamorphism in the Proterozoic Flin Flon greenstone belt, Canada: Limits on timing provided by the single-zircon Pb-evaporation technique

    SciTech Connect

    Ansdell, K.M.; Kyser, T.K. )

    1991-05-01

    The authors have used the single-zircon Pb-evaporation technique to determine the age of granitoids in the western Flin Flon domain of the Trans-Hudson orogen in Canada and to constrain the timing of molasse sedimentation, deformation, metamorphism, and mesothermal gold mineralization. The plutons were intruded between 1,860 and 1,834 Ma, about 30 m.y. after volcanism, and provide further evidence of a major period of intrusive activity throughout the Trans-Hudson orogen at that time. The older plutons (1,860 to 1,848 Ma) are synchronous with P2 deformation and the early stages of peak metamorphism, whereas the younger plutons are synchronous with or postdate the P3 deformation event. Molasse sedimentary units are deformed and metamorphosed; thus, deposition must have begun at about 1,860 Ma. Mesothermal gold mineralization postdates all plutons and may be related to high-grade peak metamorphism in adjacent terranes at about 1,815 Ma. This study also provides further support for the use of the Pb-evaporation technique as a suitable method for dating single zircons and indicates that the {sup 208}Pb/{sup 206}Pb ratio of zircons may be a useful tool in detecting the presence and source of xenocrystic zircons.

  6. Zircon Archean of the Transuralian megazone

    NASA Astrophysics Data System (ADS)

    Krasnobaev, A. A.; Puchkov, V. N.; Puzhakov, B. A.; Busharina, S. V.; Sergeeva, N. D.

    2015-12-01

    The Il'inka metamorphic complex (IC) is located in the Transuralian megazone at the latitude of the Chelyabinsk granite pluton, east of the Chelyabinsk graben. The petrological, mineralogical, and age data on the IC indicate the presence of Archean complexes during its formation. Taking into account the importance of the age data on IC, zircons were additionally analyzed using a SHRIMP. For the Transuralian megazone, the analytical data allowed us for the first time to establish the presence of the Neoarchean (2715 ± 15 Ma) substance and two stages of metamorphism of gneisses. The early stage was in the Paleoproterozoic (1970-2130 Ma). The metamorphism of 648 ± 18 Ma ends the evolution of IC.

  7. Chemical and U-Pb dating investigation of zircons from alnöites on Malaita, Solomon Islands: evidence for prolonged kimberlite-type magmatic activity

    NASA Astrophysics Data System (ADS)

    Simonetti, A.; Neal, C. R.

    2009-12-01

    The Solomon Islands chain is located in an area dominated by the Ontong Java Plateau (OJP). The island of Malaita formed at the obducted leading edge of the OJP and is geologically distinct from the islands to the west. Occurrences of pipe-like bodies of alnöite outcrop within limestones and mudstones in northern Malaita and have been seismically imaged offshore within the OJP. The Malaita alnöite is silica-undersaturated and contains a rich and varied suite of peridotite xenoliths and megacrysts (clinopyroxene, garnet, ilmenite, phlogopite, and minor zircon). The alnöite and associated megacrysts have been the focus of detailed chemical and radiogenic isotope investigations but the exact age of alnöite emplacement remains debatable. Previously reported ages for minerals associated with the Malaita alnöites include an Ar-Ar date of 34 Ma for phlogopite from a mantle xenolith, and a single 206Pb/238U date of 33.9 Ma obtained from a single zircon megacryst. Here we report on a detailed chemical (major and trace element) and U-Pb age investigation of zircon crystals recovered from rivers in the Aluta, Kwainale, and Faufaumela regions of central Malaita. The major element (SiO2, ZrO2, and HfO2) composition and back scattered electron (BSE) imaging of mm- to cm-sized zircons from the three locations were conducted by electron microprobe analysis. The data reveal a variation in the Zr/Hf ratio (45 to 57) for zircons from the Aluta area, whereas this ratio is relatively uniform in most zircons from Kwainale (Zr/Hf 45 to 48). Of importance, the BSE imaging reveals the homogeneous nature of the grains and the lack of inherited components. Trace element compositions of the zircon crystals were obtained by laser ablation (LA)-ICP-MS and these reveal similar chondrite-normalized REE patterns at variable enrichment levels for all grains analyzed; these patterns along with the U, Th, and Pb contents are similar to those documented for mantle-derived zircons formed within

  8. Accessory Pancreatic Duct Patterns and Their Clinical Implications

    PubMed Central

    Prasanna, Lokadolalu Chandracharya; Rajagopal, KV; Thomas, Huban R

    2015-01-01

    Context and Objective: Accessory pancreatic duct (APD) designed to reduce the pressure of major pancreatic duct by forming a secondary drainage channel. Few studies have mentioned the variant types of accessory ducts and their mode of formation, some of these have a clear clinical significance. Present study is aimed to evaluate the possible variations in the APD and its terminations. Materials and Methods: Forty formalin fixed adult human pancreas with duodenum in situ specimens were studied by injecting 1% aqueous eosin, followed by piece meal dissection of the head of the pancreas from posterior surface. Formation, tributaries, relations, and the termination of the accessory pancreatic duct were noted and photographed. Results: Accessory ducts revealed 50% belonged to long type, 22.5% were of short and ansa pancreatica type each, and embryonic type of duct pattern was seen in 5% specimens. 75% of long type ducts showed positive patency with eosin dye, followed by ansa type (44.4%), and least patency was found in short type (22.2%). With regard to the patency of the accessory pancreatic ducts towards their termination, we found 52.5% of the accessory ducts and 5% of the embryonic type pancreatic ducts were patent and in 42.5% of the specimen the ducts were obliterated. In 85% of specimens the minor duodenal papillae was anterosuperior to the major papilla and superior to the major papillae in 10% of the cases, and in 5% minor papillae was absent. The average distance between the two papillae was 2.35 cm. Conclusion: The knowledge of the complex anatomical relations of the gland with its duct, duodenum and bile ducts are essential for the surgeons and sinologists to plan and perform both the diagnostic as well as therapeutic procedures effectively. PMID:25954609

  9. Radon loss from zircon: emanation and diffusion as a function of grain size, temperature and fission track density

    NASA Astrophysics Data System (ADS)

    Eakin, M.; Brownlee, S. J.; Baskaran, M. M.; Barbero, L.; Walsh, C. N.

    2013-12-01

    Radon emanation from rocks and minerals is ubiquitous, but the mechanisms of radon loss are not well understood. Quantification of radon emanation rates from zircon has potential bearing on the reliability of U-Pb ages of zircon bearing rocks. The 238U decay chain includes 222Rn, a noble gas, which has a half-life of 3.82 days and can escape from the crystal structure of zircon if sufficient pathways exist, or by recoil if the parent 238U was very near the outer edge of the crystal. Loss of 222Rn ultimately leads to a deficiency of 206Pb, resulting in discordance between 238U-206Pb, 235U-207Pb, and 232Th-208Pb ages. In order to evaluate the factors affecting radon loss from zircon, we performed two experiments: one focused on the effect of microstructure on room temperature 222Rn emanation, and the other to investigate 222Rn loss by high temperature diffusion. Large (~100 g) single crystal zircon samples from each of three localities were selected for this study: Mud Tank, Malawi, and Bancroft. The zircons were pulverized and five grain sizes (500 μm, 250-500 μm, 125-250 μm, 63 - 125 μm, and < 63 μm) were separated from each. Room temperature radon emanation rates were measured for an aliquot of each grain size. To investigate the effects of microstructure, in particular fission track density, separate aliquots were heated to temperatures of 200C, 300C, 400C, 600C, and 800C for six hours after which they were cooled to room temperature and radon emanation rates were measured. Fission track densities were measured after the same annealing steps in the Mud Tank zircon, allowing quantification of 222Rn emanation rate as a function of fission track density. In general, radon emanation rates decrease with decreasing fission track density, but increase when all fission tracks are annealed, suggesting the possibility of using 222Rn to assess defect density within crystals. To investigate diffusive loss of 222Rn, we heated separate aliquots of each grain size of the

  10. Improved zircon iron corals for the 1990s

    SciTech Connect

    Decker, C. )

    1992-03-01

    CIBA-GEIGY/Drakenfeld Colors is dedicated to the research and development of consistent and cost-effective ceramic stains for the whitewares industry. After identifying the trends in color for the 1990s. CIBA-GEIGY/Drakenfeld Colors initiated an extensive R D project to improve zircon ion corals for the whitewares industry. These color trends indicated a need for stronger and cleaner zircon iron corals. This paper discusses the chemistry and crystal structure of zircon iron corals. A historical review of Drakenfeld corals will also be presented. The most recent development in Drakenfeld corals will then be compared to other commercially available zircon iron corals. Taking into consideration these comparisons, conclusions will be drawn suggesting the coral of choice for the 1990s.

  11. Mineral Chart

    MedlinePlus

    ... How Can I Help a Friend Who Cuts? Mineral Chart KidsHealth > For Teens > Mineral Chart Print A A A Text Size en ... sources of calcium. You'll also find this mineral in broccoli and dark green, leafy vegetables. Soy ...

  12. 21 CFR 884.6190 - Assisted reproductive microscopes and microscope accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OBSTETRICAL AND GYNECOLOGICAL DEVICES Assisted Reproduction.... Assisted reproduction microscopes and microscope accessories (excluding microscope stage warmers, which are classified under assisted reproduction accessories) are optical instruments used to enlarge images of...

  13. 21 CFR 884.6190 - Assisted reproductive microscopes and microscope accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OBSTETRICAL AND GYNECOLOGICAL DEVICES Assisted Reproduction.... Assisted reproduction microscopes and microscope accessories (excluding microscope stage warmers, which are classified under assisted reproduction accessories) are optical instruments used to enlarge images of...

  14. 21 CFR 884.6190 - Assisted reproductive microscopes and microscope accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OBSTETRICAL AND GYNECOLOGICAL DEVICES Assisted Reproduction.... Assisted reproduction microscopes and microscope accessories (excluding microscope stage warmers, which are classified under assisted reproduction accessories) are optical instruments used to enlarge images of...

  15. 21 CFR 884.6190 - Assisted reproductive microscopes and microscope accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OBSTETRICAL AND GYNECOLOGICAL DEVICES Assisted Reproduction.... Assisted reproduction microscopes and microscope accessories (excluding microscope stage warmers, which are classified under assisted reproduction accessories) are optical instruments used to enlarge images of...

  16. 21 CFR 884.6190 - Assisted reproductive microscopes and microscope accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OBSTETRICAL AND GYNECOLOGICAL DEVICES Assisted Reproduction.... Assisted reproduction microscopes and microscope accessories (excluding microscope stage warmers, which are classified under assisted reproduction accessories) are optical instruments used to enlarge images of...

  17. Anisotropic mechanical properties of zircon and the effect of radiation damage

    NASA Astrophysics Data System (ADS)

    Beirau, Tobias; Nix, William D.; Bismayer, Ulrich; Boatner, Lynn A.; Isaacson, Scott G.; Ewing, Rodney C.

    2016-10-01

    This study provides new insights into the relationship between radiation-dose-dependent structural damage due to natural U and Th impurities and the anisotropic mechanical properties (Poisson's ratio, elastic modulus and hardness) of zircon. Natural zircon samples from Sri Lanka (see Muarakami et al. in Am Mineral 76:1510-1532, 1991) and synthetic samples, covering a dose range of zero up to 6.8 × 1018 α-decays/g, have been studied by nanoindentation. Measurements along the [100] crystallographic direction and calculations, based on elastic stiffness constants determined by Özkan (J Appl Phys 47:4772-4779, 1976), revealed a general radiation-induced decrease in stiffness (~54 %) and hardness (~48 %) and an increase in the Poisson's ratio (~54 %) with increasing dose. Additional indentations on selected samples along the [001] allowed one to follow the amorphization process to the point that the mechanical properties are isotropic. This work shows that the radiation-dose-dependent changes of the mechanical properties of zircon can be directly correlated with the amorphous fraction as determined by previous investigations with local and global probes (Ríos et al. in J Phys Condens Matter 12:2401-2412, 2000a; Farnan and Salje in J Appl Phys 89:2084-2090, 2001; Zhang and Salje in J Phys Condens Matter 13:3057-3071, 2001). The excellent agreement, revealed by the different methods, indicates a large influence of structural and even local phenomena on the macroscopic mechanical properties. Therefore, this study indicates the importance of acquiring better knowledge about the mechanical long-term stability of radiation-damaged materials.

  18. Zircon crytallization and recycling in the magma chamber of the rhyolitic Kos Plateau Tuff (Aegean arc)

    USGS Publications Warehouse

    Bachman, O.; Charlier, B.L.A.; Lowenstern, J. B.

    2007-01-01

    In contrast to most large-volume silicic magmas in continental arcs, which are thought to evolve as open systems with significant assimilation of preexisting crust, the Kos Plateau Miff magma formed dominantly by crystal fractionation of mafic parents. Deposits from this ??? 60 km3 pyroclastic eruption (the largest known in the Aegean arc) lack xenocrystic zircons [secondary ion mass spectrometry (SIMS) U-Pb ages on zircon cores never older than 500 ka] and display Sr-Nd whole-rock isotopic ratios within the range of European mantle in an area with exposed Paleozoic and Tertiary continental crust; this evidence implies a nearly closed-system chemical differentiation. Consequently, the age range provided by zircon SIMS U-Th-Pb dating is a reliable indicator of the duration of assembly and longevity of the silicic magma body above its solidus. The age distribution from 160 ka (age of eruption by sanidine 40Ar/39Ar dating; Smith et al., 1996) to ca. 500 ka combined with textural characteristics (high crystal content, corrosion of most anhydrous phenocrysts, but stability of hydrous phases) suggest (1) a protracted residence in the crust as a crystal mush and (2) rejuvenation (reduced crystallization and even partial resorption of minerals) prior to eruption probably induced by new influx of heat (and volatiles). This extended evolution chemically isolated from the surrounding crust is a likely consequence of the regional geodynamics because the thinned Aegean microplate acts as a refractory container for magmas in the dying Aegean subduction zone (continent-continent subduction). ?? 2007 Geological Society of America.

  19. Zircon crystallization and recycling in the magma chamber of the rhyolitic Kos Plateau Tuff (Aegean arc)

    USGS Publications Warehouse

    Bachman, O.; Charlier, B.L.A.; Lowenstern, J. B.

    2007-01-01

    In contrast to most large-volume silicic magmas in continental arcs, which are thought to evolve as open systems with significant assimilation of preexisting crust, the Kos Plateau Tuff magma formed dominantly by crystal fractionation of mafic parents. Deposits from this ~60 km3 pyroclastic eruption (the largest known in the Aegean arc) lack xenocrystic zircons [secondary ion mass spectrometry (SIMS) U-Pb ages on zircon cores never older than 500 ka] and display Sr-Nd whole-rock isotopic ratios within the range of European mantle in an area with exposed Paleozoic and Tertiary continental crust; this evidence implies a nearly closed-system chemical differentiation. Consequently, the age range provided by zircon SIMS U-Th-Pb dating is a reliable indicator of the duration of assembly and longevity of the silicic magma body above its solidus. The age distribution from 160 ka (age of eruption by sanidine 40Ar/39Ar dating; Smith et al., 1996) to ca. 500 ka combined with textural characteristics (high crystal content, corrosion of most anhydrous phenocrysts, but stability of hydrous phases) suggest (1) a protracted residence in the crust as a crystal mush and (2) rejuvenation (reduced crystallization and even partial resorption of minerals) prior to eruption probably induced by new influx of heat (and volatiles). This extended evolution chemically isolated from the surrounding crust is a likely consequence of the regional geodynamics because the thinned Aegean microplate acts as a refractory container for magmas in the dying Aegean subduction zone (continent-continent subduction).

  20. Chemical evolution of Himalayan leucogranites based on an O, U-Pb and Hf study of zircon

    NASA Astrophysics Data System (ADS)

    Hopkinson, Thomas N.; Warren, Clare J.; Harris, Nigel B. W.; Hammond, Samantha J.; Parrish, Randall R.

    2015-04-01

    Crustal melting is a characteristic process at convergent plate margins, where crustal rocks are heated and deformed. Miocene leucogranite sheets and plutons are found intruded into the high-grade metasedimentary core (the Greater Himalayan Sequence, GHS) across the Himalayan orogen. Previously-published Himalayan whole-rock data suggest that these leucogranites formed from a purely meta-sedimentary source, isotopically similar to those into which they now intrude. Bulk rock analyses carry inherent uncertainties, however: they may hide contributions from different contributing sources, and post-crystallization processes such as fluid interaction may significantly alter the original chemistry. In contrast, zircon is more able to retain precise information of the contributing sources of the melt from which it crystallises whilst its resistant nature is impervious to post-magmatic processes. This multi-isotope study of Oligocene-Miocene leucogranite zircons from the Bhutan Himalaya, seeks to differentiate between various geochemical processes that contribute to granite formation. Hf and O isotopes are used to detect discrete changes in melt source while U-Pb isotopes provide the timing of zircon crystallisation. Our data show that zircon rims of Himalayan age yield Hf-O signatures that lie within the previously reported whole-rock GHS field, confirming the absence of a discernible mantle contribution to the leucogranite source. Importantly, we document a decrease in the minimum ɛHf values during Himalayan orogenesis through time, correlating to a change in Hf model age from 1.4 Ga to 2.4 Ga. Nd model ages for the older Lesser Himalayan metasediments (LHS) that underthrust the GHS are significantly older than those for the GHS (2.4-2.9 Ga compared with 1.4-2.2 Ga), and as such even minor contributions of LHS material incorporated into a melt would significantly increase the resulting Hf model age. Hence our leucogranite data suggest either a change of source within

  1. Provenance analysis and detrital zircon geochronology on the onshore Makran accretionary wedge, SE Iran: implication for the geodynamic setting

    NASA Astrophysics Data System (ADS)

    Mohammadi, Ali; Burg, Jean-Pierre; Winkler, Wilfried; Ruh, Jonas

    2014-05-01

    juvenile magma sources, which are common in continental arc environments. Point counts of 32 sandstone thin sections were performed following the Gazzi-Dikinson method. 300-400 points were counted in each thin section. The sandstones are feldspathic litharenites and litharenites. Feldspar is dominantly plagioclase (> 90%) with minor amounts of K-feldspar. Most of the quartz grains (75%) are mono-crystalline but poly-crystalline ones (maximum 25%) also occur. Rock fragments are represented by sedimentary, volcanic and metamorphic grains. Volcanic rock-fragments mostly are andesites and volcanic chert. Sedimentary lithic grains comprise mostly sandstone, siltstone, limestone and dolomite. Metamorphic lithic grains generally are low-grade schists and phyllites. In various compositional ternary diagrams, the sources of the sandstones plot in the transitional to dissected arc and recycled orogenic fields. We selected 26 samples for heavy mineral study. 200-300 grain were identified and counted in each sample. Heavy mineral suites show a highly variable composition including (1) a group of ultra-stable minerals (zircon, monazite, tourmaline, rutile, brookite, anatase and sphene) derived from a granitic continental crust sources, (2) metastable minerals delivered from variable metamorphic-grade source rocks (epidote group, garnet, staurolite, chloritoid, kyanite, andalusite, glaucophane), (3) chromian spinel from ultrabasic rocks, (4) common hornblende either supplied from metamorphic or basic igneous series, and (5) a local pyroxene-rich source in the pyroclastic sandstone formation overlying pillow lavas. Glaucophane (5-20%) occurs in several samples, which indicates high-pressure/low-temperature metamorphic rocks in the detrital source areas for Eocene and Miocene sandstones. Earlier work in the Pakistani Makran suggested that pre-Miocene sediments were supplied from the Himalaya, whereas Miocene to Recent deposits were reworked older sediments of the accretionary wedge. Our

  2. Deformation Behavior across the Zircon-Scheelite Phase Transition

    NASA Astrophysics Data System (ADS)

    Yue, Binbin; Hong, Fang; Merkel, Sébastien; Tan, Dayong; Yan, Jinyuan; Chen, Bin; Mao, Ho-Kwang

    2016-09-01

    The pressure effects on plastic deformation and phase transformation mechanisms of materials are of great importance to both Earth science and technological applications. Zircon-type materials are abundant in both nature and the industrial field; however, there is still no in situ study of their deformation behavior. Here, by employing radial x-ray diffraction in a diamond anvil cell, we investigate the dislocation-induced texture evolution of zircon-type gadolinium vanadate (GdVO4 ) in situ under pressure and across its phase transitions to its high-pressure polymorphs. Zircon-type GdVO4 develops a (001) compression texture associated with dominant slip along ⟨100 ⟩{001 } starting from 5 GPa. This (001) texture transforms into a (110) texture during the zircon-scheelite phase transition. Our observation demonstrates a martensitic mechanism for the zircon-scheelite transformation. This work will help us understand the local deformation history in the upper mantle and transition zone and provides fundamental guidance on material design and processing for zircon-type materials.

  3. Hadean diamonds in zircon from Jack Hills, Western Australia.

    PubMed

    Menneken, Martina; Nemchin, Alexander A; Geisler, Thorsten; Pidgeon, Robert T; Wilde, Simon A

    2007-08-23

    Detrital zircons more than 4 billion years old from the Jack Hills metasedimentary belt, Yilgarn craton, Western Australia, are the oldest identified fragments of the Earth's crust and are unique in preserving information on the earliest evolution of the Earth. Inclusions of quartz, K-feldspar and monazite in the zircons, in combination with an enrichment of light rare-earth elements and an estimated low zircon crystallization temperature, have previously been used as evidence for early recycling of continental crust, leading to the production of granitic melts in the Hadean era. Here we present the discovery of microdiamond inclusions in Jack Hills zircons with an age range from 3,058 +/- 7 to 4,252 +/- 7 million years. These include the oldest known diamonds found in terrestrial rocks, and introduce a new dimension to the debate on the origin of these zircons and the evolution of the early Earth. The spread of ages indicates that either conditions required for diamond formation were repeated several times during early Earth history or that there was significant recycling of ancient diamond. Mineralogical features of the Jack Hills diamonds-such as their occurrence in zircon, their association with graphite and their Raman spectroscopic characteristics-resemble those of diamonds formed during ultrahigh-pressure metamorphism and, unless conditions on the early Earth were unique, imply a relatively thick continental lithosphere and crust-mantle interaction at least 4,250 million years ago. PMID:17713532

  4. Creation of a continent recorded in zircon zoning

    USGS Publications Warehouse

    Moser, D.E.; Bowman, J.R.; Wooden, J.; Valley, J.W.; Mazdab, F.; Kita, N.

    2008-01-01

    We have discovered a robust microcrystalline record of the early genesis of North American lithosphere preserved in the U-Pb age and oxygen isotope zoning of zircons from a lower crustal paragneiss in the Neoarchean Superior province. Detrital igneous zircon cores with ??18O values of 5.1???-7.1??? record creation of primitive to increasingly evolved crust from 2.85 ?? 0.02 Ga to 2.67 ?? 0.02 Ga. Sharp chemical unconformity between cores and higher ??18O (8.4???-10.4???) metamorphic overgrowths as old as 2.66 ?? 0.01 Ga dictates a rapid sequence of arc unroofing, burial of detrital zircons in hydrosphere-altered sediment, and transport to lower crust late in upper plate assembly. The period to 2.58 ?? 0.01 Ga included ???80 m.y. of high-temperature (???700-650 ??C), nearly continuous overgrowth events reflecting stages in maturation of the subjacent mantle root. Huronian continental rifting is recorded by the youngest zircon tip growth at 2512 ?? 8 Ma (??? 600 ??C) signaling magma intraplating and the onset of rigid plate behavior. This >150 m.y. microscopic isotope record in single crystals demonstrates the sluggish volume diffusion of U, Pb, and O in zircon throughout protracted regional metamorphism, and the consequent advances now possible in reconstructing planetary dynamics with zircon zoning. ?? 2008 The Geological Society of America.

  5. Zircon U-Pb ages and Hf isotopic compositions indicate multiple sources for Grenvillian detrital zircon deposited in western Laurentia

    NASA Astrophysics Data System (ADS)

    Howard, Amanda L.; Farmer, G. Lang; Amato, Jeffrey M.; Fedo, Christopher M.

    2015-12-01

    Combined U-Pb ages and Hf isotopic data from 1.0 Ga to 1.3 Ga (Grenvillian) detrital zircon in Neoproterozoic and Cambrian siliciclastic sedimentary rocks in southwest North America, and from igneous zircon in potential Mesoproterozoic source rocks, are used to better assess the provenance of detrital zircon potentially transported across Laurentia in major river systems originating in the Grenville orogenic highlands. High-precision hafnium isotopic analyses of individual ∼1.1 Ga detrital zircon from Neoproterozoic siliciclastic sedimentary rocks in Sonora, northern Mexico, reveal that these zircons have low εHf (0) (-22 to -26) and were most likely derived from ∼1.1 Ga granitic rocks embedded in local Mojave Province Paleoproterozoic crust. In contrast, Grenvillian detrital zircons in Cambrian sedimentary rocks in Sonora, the Great Basin, and the Mojave Desert, have generally higher εHf (0) (-15 to -21) as demonstrated both by high precision solution-based, and by lower precision laser ablation, ICPMS data and were likely derived from more distal sources further to the east/southeast in Laurentia. Comparison to new and existing zircon U-Pb geochronology and Hf isotopic data from Grenvillian crystalline rocks from the Appalachian Mountains, central and west Texas, and from Paleoproterozoic terranes throughout southwest North America reveals that zircon in Cambrian sandstones need not entirely represent detritus transported across the continent from Grenville province rocks in the vicinity of the present-day southern Appalachian Mountains. Instead, these zircons could have been derived from more proximal, high εHf (0), ∼1.1 Ga, crystalline rocks such as those exposed today in the Llano Uplift in central Texas and in the Franklin Mountains of west Texas. Regardless of the exact source(s) of the Grenvillian detrital zircon, new and existing whole-rock Nd isotopic data from Neoproterozoic to Cambrian siliciclastic sedimentary rocks in the Mojave Desert

  6. Four accessory (supernumerary) intrathoracic ribs: a case report.

    PubMed

    Prados, Jose; Archilla, Francisco; Melguizo, Consolación; Aranega, Antonia

    2013-09-01

    Accessory (supernumerary) intrathoracic ribs are a very rare congenital disorder. Here, we present the first case of multiple supernumerary intrathoracic ribs in an adult, which are present consecutively between ribs 1 and 4 and without articulation with the vertebrae. Despite this, anatomical variation is usually silent and accidentally discovered; its knowledge can prevent confusion with other structures during imaging diagnostic techniques of thoracic pathologies.

  7. 21 CFR 876.5900 - Ostomy pouch and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... attached to the patient's skin by an adhesive material and that is intended for use as a receptacle for... generic type of device and its accessories includes the ostomy pouch, ostomy adhesive, the disposable... bag, ostomy drainage bag with adhesive, stomal bag, ostomy protector, and the ostomy size...

  8. 21 CFR 876.5900 - Ostomy pouch and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... attached to the patient's skin by an adhesive material and that is intended for use as a receptacle for... generic type of device and its accessories includes the ostomy pouch, ostomy adhesive, the disposable... bag, ostomy drainage bag with adhesive, stomal bag, ostomy protector, and the ostomy size...

  9. 21 CFR 876.5900 - Ostomy pouch and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... attached to the patient's skin by an adhesive material and that is intended for use as a receptacle for... generic type of device and its accessories includes the ostomy pouch, ostomy adhesive, the disposable... bag, ostomy drainage bag with adhesive, stomal bag, ostomy protector, and the ostomy size...

  10. 21 CFR 876.5900 - Ostomy pouch and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... attached to the patient's skin by an adhesive material and that is intended for use as a receptacle for... generic type of device and its accessories includes the ostomy pouch, ostomy adhesive, the disposable... bag, ostomy drainage bag with adhesive, stomal bag, ostomy protector, and the ostomy size...

  11. 21 CFR 884.1690 - Hysteroscope and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... direct viewing of the cervical canal and the uterine cavity by a telescopic system introduced into the... specialized instrument or device delivery system; do not have adapters, connectors, channels, or do not have portals for electrosurgical, laser, or other power sources. Such hysteroscope accessory...

  12. 21 CFR 884.1690 - Hysteroscope and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... direct viewing of the cervical canal and the uterine cavity by a telescopic system introduced into the... specialized instrument or device delivery system; do not have adapters, connectors, channels, or do not have portals for electrosurgical, laser, or other power sources. Such hysteroscope accessory...

  13. 14 CFR 121.251 - Engine accessory section diaphragm.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Engine accessory section diaphragm. 121.251... REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Special Airworthiness Requirements § 121.251 Engine... complies with § 121.247 must be provided on air-cooled engines to isolate the engine power section and...

  14. 14 CFR 121.251 - Engine accessory section diaphragm.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Engine accessory section diaphragm. 121.251... REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Special Airworthiness Requirements § 121.251 Engine... complies with § 121.247 must be provided on air-cooled engines to isolate the engine power section and...

  15. 21 CFR 876.5820 - Hemodialysis system and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... system, and accessories. Blood from a patient flows through the tubing of the extracorporeal blood system..., conductivity, flow rate, and pressure of the dialysate and circulates dialysate through the dialysate... (liquid or powder) and alarms to indicate abnormal dialysate conditions. This dialysate delivery...

  16. 21 CFR 884.2740 - Perinatal monitoring system and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Perinatal monitoring system and accessories. 884.2740 Section 884.2740 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... heart rate by means of combining and coordinating uterine contraction and fetal heart monitors...

  17. 21 CFR 884.2740 - Perinatal monitoring system and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Perinatal monitoring system and accessories. 884.2740 Section 884.2740 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... heart rate by means of combining and coordinating uterine contraction and fetal heart monitors...

  18. 21 CFR 884.2740 - Perinatal monitoring system and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Perinatal monitoring system and accessories. 884.2740 Section 884.2740 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... heart rate by means of combining and coordinating uterine contraction and fetal heart monitors...

  19. 21 CFR 884.2640 - Fetal phonocardiographic monitor and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Fetal phonocardiographic monitor and accessories. 884.2640 Section 884.2640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... phonocardiographic monitor is a device designed to detect, measure, and record fetal heart sounds electronically,...

  20. 21 CFR 884.2640 - Fetal phonocardiographic monitor and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Fetal phonocardiographic monitor and accessories. 884.2640 Section 884.2640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... phonocardiographic monitor is a device designed to detect, measure, and record fetal heart sounds electronically,...