Coexisting Amphiboles     

KLEIN  CORNELIS  JR. 《Journal of Petrology》1968,9(2):281-330

Chemical analyses for the following amphibole pairs are presented:anthophyllite—tremolite (or actinolite, or hornblende),cummingtonite (or grunerite)–actinolite (or hornblende),cummingtonite (or grunerite)–anthophyllite (or gedrite),and manganoan cummingtonitemagnesioriebeckite. Nineteen analyses of such pairs are quoted from the literature,and thirty-seven additional pairs have been newly analyzed byelectron probe techniques. Quantitative microprobe determinationsof Si, Al, Fe, Mn, Mg, Ca, and Na were made on polished thin-sections,using naturally occurring, analyzed, homogeneous amphibolesas standards. The literature analyses and the electron probeanalyses for metamorphic, two-amphibole assemblages are givenfor amphiboles in physical contact, which show no textural evidenceof one amphibole being a reaction or alteration product of theother. The chemical data for some of the volcanic, two—amphiboleassemblages were obtained from occurrences that probably donot represent equilibrium pairs. The chemical data are used to determine the extent of the miscibilitygaps between the various amphibole series and the fractionationof the major elements between the two amphiboles of a pair.Anthophyllite and members of the cummingtonite-grunerite seriesgenerally have a larger Fe(total)/Mg ratio than the coexistingcalcic amphibole. The maximum CaO, Al₂O₃and Na₂O contents ofcummingtonite in metamorphic cummingtonite—hornblendepairs are 19 and 32, 02 weight per cent, respectively. Themaximum CaO, A1₂O₃, and Na₂O contents of cummingtonite in metamorphiccummingtonite-hornblende pairs are 19, 32, and 02 weightper cent, respectively. Larger CaO and Al₂O₃ values reportedin the literature were found to be too high because of admixtureof actinolite or hornblende in the analyzed separates. Smallamounts of MnO tend to concentrate preferentially in anthophylliteor cummingtonite of anthophyllite-hornblende and cummingtonite-hornblendepairs. Anthophyllite-cummingtonite pairs may show very similarFe(total)/Mg ratios and differ slightly in Al₂O₃ content only.  相似文献   

Phengite-hosted LILE Enrichment in Eclogite and Related Rocks: Implications for Fluid-Mediated Mass Transfer in Subduction Zones and Arc Magma Genesis   总被引：2，自引：1，他引：1       下载免费PDF全文

Sorensen    Sorena S.; Grossman  Jeffrey N.; Perfit  Michael R. 《Journal of Petrology》1997,38(1):3-34

Geochemical differences between island arc basalts (IAB) andocean-floor basalts (mid-ocean ridge basalts; MORB) suggestthat the large-ion lithophile elements (LILE) K, Ba, Rb andCs are probably mobilized in subduction zone fluids and melts.This study documents LILE enrichment of eclogite, amphibolite,and epidote ± garnet blueschist tectonic blocks and relatedrocks from melanges of two subduction complexes. The samplesare from six localities of the Franciscan Complex, California,and related terranes of Oregon and Baja California, and fromthe Samana Metamorphic Complex, Samana Peninsula, DominicanRepublic. Most Franciscan blocks are MORB-like in their contentsof rare earth elements (REE) and high field strength elements(HFSE); in contrast, most Samana blocks show an IAB signatureof these elements. The whole-rock K₂O contents of both groupsrange from 1 to 3 wt %; K, Ba, Rb, and Cs are all strongly intercorrelated.Many blocks display K/Ba similar to metasomatized transitionzones and rinds at their outer margins. Some transition zonesand rinds are enriched in LILE compared with host blocks; othersare relatively depleted in these elements. Some LILE-rich blockscontain ‘early’ coarse-grained muscovite that isaligned in the foliation defined by coarse-grained omphaciteor amphibole grains. Others display ‘late’ muscovitein veins and as a partial replacement of garnet; many containboth textural types. The muscovite is phengite that contains3.25–3.55 Si per 11 oxygens, and 0.25–0.50 Mg per11 oxygens. Lower-Si phengite has a significant paragonite component:Na per 11 oxygens ranges to 0.12. Ba contents of phengite rangeto over 1 wt % (0.027 per 11 oxygens). Ba in phengite does notcovary strongly with either Na or K. Ba contents of phengiteincrease from some blocks to their transition zones or rinds,or from blocks to their veins. Averaged K/Ba ratios for phengiteand host samples define an array which describes other subsamplesof the block and other analyzed blocks. Phengite carries essentiallyall of the LILE in otherwise mafic eclogite, amphibolite, andgarnet blueschist blocks that are enriched in these elementscompared with MORB. It evidently tracks a distinctive type ofLILE metasomatism that attends both high-T and retrograde subductionzone metamorphism. An obvious source for the LILE is a fluidin equilibrium with metasedimentary rocks. High-grade semipeliticschists from subduction complexes and subductable sediment displayLILE values that resemble those seen in the most LILE-rich blocks.Modeling of Ba and Ti suggests that 1–40 wt % of phengiteadded to MORB can produce their observed LILE enrichment. Thus,the release of LILE from such rocks to fluids or melts in veryhigh-T and -P parts of subduction zones probably depends criticallyon the stability and solubility relations of phengite, whichis thought to be stable at pressures as high as 95–110kbar at T=750–1050°C. KEY WORDS: geochemistry; LT eclogite; mineral chemistry; metasomatism; phengite  相似文献   

Chemical Petrology of Grenville Schists near Fernleigh, Ontario     

HOUNSLOW  A. W.; MOORE  J. M.  JR 《Journal of Petrology》1967,8(1):1-28

A suite of mica schists from the staurolite zone was studiedin detail. Phase rule considerations and distribution relationsindicate that chemical equilibrium was attained within the samplevolume. Iron-magnesium ratios of the silicates vary greatly,and correlate with rock ferrous-ferric ratio, as does the oxidemineral mode. Rock oxidation state varies locally, and is probablydependent on the composition of the original sediment. Distribution coefficients for Fe, Mg, and Mn among garnet, biotote,and staurolite show no vaiation attributable to temperature.Partition of Fe and Mg between staurolite and biotite is regular,but non-ideal. The staurolite structure permits only limited(15–35 percent) substitution of Mg for Fe.  相似文献   

Primordial compositions of refractory inclusions   总被引：1，自引：0，他引：1  

L. Grossman  S.B. Simon  M.H. Thiemens  R.W. Williams  T. Ding  R.N. Clayton  T.K. Mayeda 《Geochimica et cosmochimica acta》2008,72(12):3001-3021

Bulk chemical and O-, Mg- and Si-isotopic compositions were measured for each of 17 Types A and B refractory inclusions from CV3 chondrites. After bulk chemical compositions were corrected for non-representative sampling in the laboratory, the Mg- and Si-isotopic compositions of each inclusion were used to calculate its original chemical composition assuming that the heavy-isotope enrichments of these elements are due to Rayleigh fractionation that accompanied their evaporation from CMAS liquids. The resulting pre-evaporation chemical compositions are consistent with those predicted by equilibrium thermodynamic calculations for high-temperature nebular condensates, but only if different inclusions condensed from nebular regions that ranged in total pressure from 10⁻⁶ to 10⁻¹ bar, regardless of whether they formed in a system of solar composition or in one enriched in dust of ordinary chondrite composition relative to gas by a factor of 10 compared to solar composition. This is similar to the range of total pressures predicted by dynamic models of the solar nebula for regions whose temperatures are in the range of silicate condensation temperatures. Alternatively, if departure from equilibrium condensation and/or non-representative sampling of condensates in the nebula occurred, the inferred range of total pressure could be smaller. Simple kinetic modeling of evaporation successfully reproduces observed chemical compositions of most inclusions from their inferred pre-evaporation compositions, suggesting that closed-system isotopic exchange processes did not have a significant effect on their isotopic compositions. Comparison of pre-evaporation compositions with observed ones indicates that 80% of the enrichment in refractory CaO + Al₂O₃ relative to more volatile MgO + SiO₂ is due to initial condensation and 20% due to subsequent evaporation for both Types A and B inclusions.  相似文献   

Factors Influencing Methane Distribution in Texas Ground Water     

Chuanlun Zhang  Ethan L. Grossman  James W. Ammerman 《Ground water》1998,36(1):58-66

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A case study of GATE convective activity     

R.N. Mower  G.L. Austin  A.K. Betts  C. Gautier  R. Grossman  J. Kelley 《大气与海洋》2013,51(1):46-59

Abstract

This paper presents the synoptic and meso‐scale aspects of the intense convective activity of 2 September 1974 in the Eastern Atlantic. Two main features were evident in the GATE B‐scale array: a broad convective band associated with the 700‐mb trough, and long and narrow lines of convection oriented SE‐NW. One of these lines, which moved across the B‐scale array and was penetrated by several aircraft, is described in detail. The structure of the cloud and precipitation fields, obtained from the analysis of satellite and radar data, indicates that intense precipitation occurred mainly at the leading edge of the line where new cells were continuously generating. Cross‐sections through the line (from boom, aircraft and tethered balloon data) show a gust front at the surface, a downdraft region associated with the rain area, and a wind shift in the lowest 300 m. The circulations around and within this line appear to be similar to a class of tropical squall‐lines studied at length by Zipser, (1977) and Houze (1977) with the important difference that the horizontal gradients of the dynamic and thermodynamic variables across the line were typically weaker.  相似文献   

The Meteoritical Bulletin,No. 102          下载免费PDF全文

Alex Ruzicka  Jeffrey Grossman  Audrey Bouvier  Christopher D. K. Herd  Carl B. Agee 《Meteoritics & planetary science》2015,50(9):1662-1662

Meteoritical Bulletin 102 contains 3141 meteorites including 12 falls (Boumdeid (2003), Boumdeid (2011), Braunschweig, Chelyabinsk, Dongyang, Draveil, Heyetang, Indian Butte, Katol, Ladkee, Ouadangou, Xining), with 2611 ordinary chondrites, 264 HED achondrites, 124 carbonaceous chondrites, 30 ureilites, 20 Martian meteorites, 16 primitive achondrites, 16 Rumuruti chondrites, 15 mesosiderites, 12 iron meteorites, 10 lunar meteorites, 9 enstatite chondrites, 4 enstatite achondrites, 4 Pallasites, 4 ungrouped achondrites, and 2 angrites, and with 1708 from Antarctica, 956 from Africa, 294 from South America, 126 from Asia, 47 from North America, 6 from Europe (including Russia), and 4 from Oceania. Information about approved meteorites can be obtained from the Meteoritical Bulletin Database (MBD) available on line at http://www.lpi.usra.edu/meteor/ .  相似文献   

The Meteoritical Bulletin,No. 79, 1996 July: Recently classified specimens in the United States Antarctic Meteorite Collection (1994–1996)*     

Jeffrey N. Grossman  Roberta Score 《Meteoritics & planetary science》1996,31(Z4):A161-A174

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Oxygen-isotope record of Late-Glacial climatic change in western Ireland     

KARIN AHLBERG  ELISABETH ALMGREN  H. E. WRIGHT JR.    EMI ITO  SARAH HOBBIE 《Boreas: An International Journal of Quaternary Research》1996,25(4):257-267

Oxygen-isotope profiles for the Late-Glacial carbonate sediments from Red Bog and adjacent Lough Gur in County Limerick in western Ireland are readily correlated with the classical hiozones delineated on pollen diagrams for the same cores. The estimated summer temperatures of the Bølling/Allerød were as high as those in the early Holocene and are correlated with increasing Milankovitch summer insolation. This warm phase was abruptly terminated in the Younger Dryas cold episode by a depletion of 4% in δ¹⁸O, suggesting a summer atmospheric temperature decrease of about 12°C, comparable to that inferred from fossil beetle data. The Younger Dryas phase is attributed to a major cooling of the sea-surface temperature by a postulated discharge of icebergs similar to that of the Heinrich events, for the icebergs were much more effective than simple meltwater in cooling the sea surface and thus the climate over Europe. Shorter-term cool phases (Older Dryas. Gerzensee. Preboreal oscillation) are also recognized.  相似文献   

Multi-technique approach to characterise the effects of cryopreservation on larval development of the Pacific oyster (Crassostrea gigas)     

S Suneja  AB Rusk  JR Morrish  HR Tervit  LT McGowan 《新西兰海洋与淡水研究杂志》2014,48(3):335-349

Cryopreservation experiments were conducted on D-stage larvae of the Pacific oyster (Crassostrea gigas) to investigate the effects of two cryoprotectant solutions and three cooling rates on larval development from 1 to 22 days post-fertilisation. Cryoprotectant solutions were made up to final concentrations (after 1:1 dilution with larvae) of 10% ethylene glycol, 1% polyvinylpyrrolidone and either 0.2 or 0.4 M trehalose. Three cooling rates (0.5, 1 and 2 °C min^?1 between ?10 and ?35 °C post-holding) were tested in an orthogonal design with the two cryoprotectants. Results indicate that control larvae out-performed all cryopreservation treatments for survival, feeding consumption and shell length parameters. However, larvae exposed to 0.4 M trehalose did considerably better than those exposed to 0.2 M trehalose, regardless of cooling rate conditions. Scanning electron and light microscopy observations were used to assess larval morphology and organogenesis, indicating that treatments with surviving larvae were morphologically and developmentally similar to control larvae.  相似文献