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91.
92.
Michael Ed. Hohn 《Lithos》1979,12(4):317-324
Principal components analysis of elemental distributions among minerals elucidate chemical, thermal, and equilibrium effects. Previous approaches in applying this multivariate statistical method to petrologic data are united into a single model, so-called three-mode principal components analysis. The major advantage of the model lies in the separate analysis of each of the three modes: element, mineral, and sample. The three sets of principal components are related through a “core matrix”. The model accommodates the ordination of pair-wise combination of the modes, such as samples and minerals in visualization of multidimensional tie-lines. Because of its generality, the model permits great flexibility in the study of petrologic data. 相似文献
93.
Ed L. Schrader 《Environmental Geology》1991,17(2):157-166
Several complex methods of remediation are applied to open water oil spills. Sorbing the liquid hydrocarbons with polypropylene booms is an effective and less complex means of treating such events. There are, however, a variety of commercially available booms which display different performances in sorbing different viscosity hydrocarbons. There is no acceptable A.S.T.M. protocol to evaluate these booms for performance efficiency in various weather and hydrocarbon viscosity scenarios. The current paper proposes such a protocol and evaluates the most commonly used sorbent products with the new test procedures. Nine specific performance criteria, based on actual field applications, are demonstrated. 相似文献
94.
Subduction factory processes beneath the Guguan cross-chain, Mariana Arc: no role for sediments, are serpentinites important? 总被引:1,自引:0,他引:1
Robert J. Stern Ed Kohut Sherman H. Bloomer Matthew Leybourne Matthew Fouch Jeff Vervoort 《Contributions to Mineralogy and Petrology》2006,151(2):202-221
We need to understand chemical recycling at convergent margins and how chemical interactions between subducted slab and the
overlying mantle wedge affect mantle evolution and magmagenesis. This requires distinguishing contributions from recycled
individual subducted components as well as those contributed by the mantle. We do this by examining magmatic products generated
at different depths above a subduction zone, in an intra-oceanic arc setting. The Guguan cross-chain in the intra-oceanic
Mariana arc overlies subducted Jurassic Pacific plate lithosphere at depths of ~125--230 km and erupts mostly basalt. Basalts
from rear-arc volcanoes are more primitive than those from the magmatic front, in spite of being derived by lower degrees
of melting of less-depleted mantle. Rear-arc magmas also show higher temperatures and pressures of equilibration. Coexisting
mineral compositions become more MORB- or OIB-like with increasing height above the subduction zone. Trace element and isotopic
variations indicate that the subduction component in cross-chain lavas diminishes with increasing depth to the subduction
zone, except for water contents. There is little support for the idea that melting beneath the Mariana Trough back-arc basin
depleted the source region of arc magmas, but melting to form rear-arc volcanoes may have depleted the source of magmatic
front volcanoes. Enrichments in rear-arc lavas were not caused by sediment melting; the data instead favor an OIB-type mantle
that has been modestly affected by subduction zone fluids. Our most important conclusion is that sediment fluids or melts
are not responsible for the K--h relationship and other cross-chain chemical and isotopic variations. We speculate that an
increasing role for supercritical fluids released from serpentinites interacting with modestly enriched mantle might be responsible
for cross-chain geochemical and isotopic variations.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. 相似文献
95.
An analysis is made of microseismic and seismic activity for a period of about 3 months prior to the 1958 eruption in the Virunga Volcanoes, Western Rift Valley of Central Africa. It is believed that it would have been possible to predict the eruption some 30 h before, on the basis of two series of small earthquakes preceeding the 2 outbrakes by some 50 h, and presenting an exponential decay of the total number of shocks. 相似文献
96.
Marcus Gutjahr Louise Bordier Eric Douville Jesse Farmer Gavin L. Foster Ed C. Hathorne Brbel Hnisch Damien Lemarchand Pascale Louvat Malcolm McCulloch Johanna Noireaux Nicola Pallavicini James W. B. Rae Ilia Rodushkin Philippe Roux Joseph A. Stewart Franois Thil Chen‐Feng You 《Geostandards and Geoanalytical Research》2021,45(1):59-75
Boron isotopes in marine carbonates are increasingly used to reconstruct seawater pH and atmospheric pCO2 through Earth’s history. While isotope ratio measurements from individual laboratories are often of high quality, it is important that records generated in different laboratories can equally be compared. Within this Boron Isotope Intercomparison Project (BIIP), we characterised the boron isotopic composition (commonly expressed in δ11B) of two marine carbonates: Geological Survey of Japan carbonate reference materials JCp‐1 (coral Porites) and JCt‐1 (giant clam Tridacna gigas). Our study has three foci: (a) to assess the extent to which oxidative pre‐treatment, aimed at removing organic material from carbonate, can influence the resulting δ11B; (b) to determine to what degree the chosen analytical approach may affect the resultant δ11B; and (c) to provide well‐constrained consensus δ11B values for JCp‐1 and JCt‐1. The resultant robust mean and associated robust standard deviation (s*) for un‐oxidised JCp‐1 is 24.36 ± 0.45‰ (2s*), compared with 24.25 ± 0.22‰ (2s*) for the same oxidised material. For un‐oxidised JCt‐1, respective compositions are 16.39 ± 0.60‰ (2s*; un‐oxidised) and 16.24 ± 0.38‰ (2s*; oxidised). The consistency between laboratories is generally better if carbonate powders were oxidatively cleaned prior to purification and measurement. 相似文献
97.
Management of coastal ecosystems necessitates the evaluation of pollutant loading based on adequate source discrimination. Monitoring of sediments and fish on the shelf off San Diego has shown that some areas on the shelf are contaminated with polychlorinated biphenyls (PCBs). Here, we present an analysis of PCB contamination in fish on the shelf off San Diego designed to discriminate possible sources. The analysis was complicated by the variability of species available for analysis across the shelf, variable affinities of PCBs among species, and non-detects in the data. We utilized survival regression analysis to account for these complications. We also examined spatial patterns of PCBs in bay and offshore sediments and reviewed more than 20 years of influent and effluent data for local wastewater treatment facilities. We conclude that most PCB contamination in shelf sediments and fish is due to the ongoing practice of dumping contaminated sediments dredged from San Diego Bay. 相似文献
98.
Hannah H. Kaplan Victoria E. Hamilton Ellen S. Howell F. Scott Anderson M. Antonella Barrucci John Brucato Thomas H. Burbine Beth E. Clark Ed A. Cloutis Harold C. Connolly Elisabetta Dotto Joshua P. Emery Sonia Fornasier Cateline Lantz Lucy F. Lim Frederic Merlin Alice Praet Dennis C. Reuter Scott A. Sandford Amy A. Simon Driss Takir Dante S. Lauretta 《Meteoritics & planetary science》2020,55(4):744-765
The primary objective of the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS‐REx) mission is to return to Earth a pristine sample of carbonaceous material from the primitive asteroid (101955) Bennu. To support compositional mapping of Bennu as part of sample site selection and characterization, we tested 95 spectral indices on visible to near infrared laboratory reflectance data from minerals and carbonaceous meteorites. Our aim was to determine which indices reliably identify spectral features of interest. Most spectral indices had high positive detection rates when applied to spectra of pure, single‐component materials. The meteorite spectra have fewer and weaker absorption features and, as a result, fewer detections with the spectral indices. Indices targeting absorptions at 0.7 and 2.7–3 μm, which are attributable to hydrated minerals, were most successful for the meteorites. Based on these results, we identified a set of 17 indices that are most likely to be useful at Bennu. These indices detect olivines, pyroxenes, carbonates, water/OH‐bearing minerals, serpentines, ferric minerals, and organics. Particle size and albedo are known to affect band depth but had a negligible impact on interpretive success with spectral indices. Preliminary analysis of the disk‐integrated Bennu spectrum with these indices is consistent with expectations given the observed absorption near 3 μm. Our study prioritizes spectral indices to be used for OSIRIS‐REx spectral analysis and mapping and informs the reliability of all index‐derived data products, including a science value map for sample site selection. 相似文献
99.
100.
The processes that govern the predictability of decadal variations in the North Atlantic meridional overturning circulation (MOC) are investigated in a long control simulation of the ECHO-G coupled atmosphere?Cocean model. We elucidate the roles of local stochastic forcing by the atmosphere, and other potential ocean processes, and use our results to build a predictive regression model. The primary influence on MOC variability is found to come from air?Csea heat fluxes over the Eastern Labrador Sea. The maximum correlation between such anomalies and the variations in the MOC occurs at a lead time of 2?years, but we demonstrate that the MOC integrates the heat flux variations over a period of 10?years. The corresponding univariate regression model accounts for 74.5% of the interannual variability in the MOC (after the Ekman component has been removed). Dense anomalies to the south of the Greenland-Scotland ridge are also shown to precede the overturning variations by 4?C6?years, and provide a second predictor. With the inclusion of this second predictor the resulting regression model explains 82.8% of the total variance of the MOC. This final bivariate model is also tested during large rapid decadal overturning events. The sign of the rapid change is always well represented by the bivariate model, but the magnitude is usually underestimated, suggesting that other processes are also important for these large rapid decadal changes in the MOC. 相似文献