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951.
Nicole?E.?MooreEmail author Susan?M.?DeBari 《Contributions to Mineralogy and Petrology》2012,163(3):521-546
Five mafic lava flows located on the southern flank of Mount Baker are among the most primitive in the volcanic field. A comprehensive
dataset of whole rock and mineral chemistry reveals the diversity of these mafic lavas that come from distinct sources and
have been variably affected by ascent through the crust. Disequilibrium textures present in all of the lavas indicate that
crustal processes have affected the magmas. Despite this evidence, mantle source characteristics have been retained and three
primitive endmember lava types are represented. These include (1) modified low-K tholeiitic basalt (LKOT-like), (2) typical
calc-alkaline (CA) lavas, and (3) high-Mg basaltic andesite and andesite (HMBA and HMA). The Type 1 endmember, the basalt
of Park Butte (49.3–50.3 wt% SiO2, Mg# 64–65), has major element chemistry similar to LKOT found elsewhere in the Cascades. Park Butte also has the lowest
overall abundances of trace elements (with the exception of the HREE), indicating it is either derived from the most depleted
mantle source or has undergone the largest degree of partial melting. The Type 2 endmember is represented by the basalts of
Lake Shannon (50.7–52.6 wt% SiO2, Mg# 58–62) and Sulphur Creek (51.2–54.6 wt% SiO2, Mg# 56–57). These two lavas are comparable to calc-alkaline rocks found in arcs worldwide and have similar trace element
patterns; however, they differ from each other in abundances of REE, indicating variation in degree of partial melting or
fractionation. The Type 3 endmember is represented by the HMBA of Tarn Plateau (51.8–54.0 wt% SiO2, Mg# 68–70) and the HMA of Glacier Creek (58.3–58.7 wt% SiO2, Mg# 63–64). The strongly depleted HREE nature of these Type 3 units and their decreasing Mg# with increasing SiO2 suggests fractionation from a high-Mg basaltic parent derived from a source with residual garnet. Another basaltic andesite
unit, Cathedral Crag (52.2–52.6 wt% SiO2, Mg# 55–58), is an Mg-poor differentiate of the Type 3 endmember. The calc-alkaline lavas are least enriched in a subduction
component (lowest H2O, Sr/PN, and Ba/Nb), the LKOT-like lavas are intermediate (moderate Sr/PN and Ba/Nb), and the HMBA are most enriched (highest H2O, Sr/PN and Ba/Nb). The generation of the LKOT-like and calc-alkaline lavas can be successfully modeled by partial melting of a spinel
lherzolite with variability in composition of slab flux and/or mantle source depletion. The HMBA lavas can be successfully
modeled by partial melting of a garnet lherzolite with slab flux compositionally similar to the other lava types, or less
likely by partial melting of a spinel lherzolite with a distinctly different, HREE-depleted slab flux. 相似文献
952.
Maciej J. Bojanowski Bogus?aw Bagiński Euan Clarkson Ray Macdonald Leszek Marynowski 《Contributions to Mineralogy and Petrology》2012,164(2):245-259
Zircon occurs in voids and cracks in phosphatic coprolites enclosed in siderite concretions in Mississippian shales near Edinburgh, Scotland. The zircon formed during hydrothermal alteration of early-diagenetic concretions and occurs as spherical aggregates of prismatic crystals, sometimes radiating. Vitrinite reflectance measurements indicate temperatures of ~270°C for the zircon-bearing concretions and the host shales. Molecular parameter values based on dibenzothiophene and phenanthrene distribution and occurrence of di- and tetra-hydro-products of polycyclic aromatic compounds suggest that the rocks experienced relatively high-temperature aqueous conditions related to hydrothermal fluids, perhaps associated with neighboring mafic intrusions. The zircon was dissolved from the concretions, transported in fluids, and reprecipitated in voids. This is the first record of the precipitation of authigenic zircon in sedimentary rock as a new phase, not as outgrowths. 相似文献
953.
Karl?Hans?Wedepohl Klaus?SimonEmail author 《Contributions to Mineralogy and Petrology》2012,164(4):693-696
During the Variscan orogeny in Central Europe, partial melting in the lower continental crust formed granitic magmas, which intruded into the upper crust and left compounds of Ca (plus Eu2+), Mg, etc. in the lower crust. From the late Paleozoic decomposition of the tonalitic upper crust, sedimentary graywackes were produced reflecting the composition of this crust. The repeated reworking of the sedimentary cover caused the formation of sands. Sandstones as their products of consolidation contain increasing fractions of quartz and decreasing feldspar from Carboniferous and Triassic to Cretaceous age. A distinct negative Eu anomaly characterizes the majority of these rocks. The latter is imprinted by the Variscan magmatism. Quartz as used for numerous Medieval wood ash glasses is marked for its Central European origin by a distinct negative Eu anomaly in contrast to many soda glasses produced outside Germany mostly with a small or none Eu anomaly. 相似文献
954.
During the last two decades, there has been growing interest in the integration of existing ideas and data to produce new
synthetic models and hypotheses leading to discovery and advancement in estuarine and coastal science. This essay offers an
integrated definition of what is meant by synthesis research and discusses its importance for exploiting the rapid expansion
of information availability and for addressing increasingly complex environmental problems. Approaches and methods that have
been used in published synthetic coastal research are explored and a list of essential steps is developed to provide a foundation
for conducting synthetic research. Five categories of methods used widely in coastal synthesis studies are identified: (1)
comparative cross-system analysis, (2) analysis of time series data, (3) balance of cross-boundary fluxes, (4) system-specific
simulation modeling, and (5) general systems simulation modeling. In addition, diverse examples are used to illustrate how
these methods have been applied in previous studies. We discuss the urgent need for developing curricula for classroom and
experiential teaching of synthesis in coastal science to undergraduate and graduate students, and we consider the societal
importance of synthetic research to support coastal resource management and policy development. Finally, we briefly discuss
the crucial challenges for future growth and development of synthetic approaches to estuarine and coastal research. 相似文献
955.
Bernard?HenryEmail author Kalin?Naydenov Dimo?Dimov Diana?Jordanova Neli?Jordanova 《International Journal of Earth Sciences》2012,101(3):747-759
The Kapitan-Dimitrievo pluton was emplaced within the 15 km wide Maritsa shear zone during the Late Cretaceous. It has well-known
U–Pb zircon age (78.54 ± 0.13 Ma) and appears as a late-syntectonic intrusion that marked the last ductile deformation in
the Maritsa shear zone. Magnetite is believed to be the main carrier of the magnetic fabric in this pluton, and crystallized
mainly late, after the main rock-forming minerals. Two fabrics are recorded, a visible syn-magmatic fabric (due to magma flow)
and magnetic late-magmatic fabric (related to regional stresses). Although different, both are mainly related to the shearing
along this shear zone. These results constrain in age the dextral strike-slip controlled emplacement and evolution of the
Late Cretaceous plutons from Central Bulgaria. 相似文献
956.
Paleo- and Neoproterozoic magmatic and tectonometamorphic evolution of the Isla Cristalina de Rivera (Nico Pérez Terrane, Uruguay) 总被引:1,自引:0,他引:1
Pedro Oyhant?abal Martin Wagner-Eimer Klaus Wemmer Bernhard Schulz Robert Frei Siegfried Siegesmund 《International Journal of Earth Sciences》2012,101(7):1745-1762
The Isla Cristalina de Rivera crystalline complex in northeastern Uruguay underwent a multistage magmatic and metamorphic evolution. Based on SHRIMP U–Pb zircon, Th–U–Pb monazite (CHIME-EPMA method) and K–Ar age data from key units several events can be recognized: (1) multistage magmatism at 2,171–2,114?Ma, recorded on zircon of the granulitic orthogneisses and their 2,093–2,077?Ma overgrowths; (2) a distinct amphibolite facies metamorphism at ~1,980?Ma, recorded by monazite; (3) greenschist facies reworking and shearing at ca. 606?Ma (monazite and K–Ar on muscovite) along the Rivera Shear Zone, and finally (4) intrusion of the post-tectonic Sobresaliente and Las Flores granites at around 585?Ma. Lithological similarities, geographic proximity and coeval magmatic and metamorphic events indicate a similar tectonometamorphic evolution for the Isla Cristalina de Rivera, the Valentines Block in Uruguay and the Santa María Chico Granulitic Complex in southern Brazil, since at least 2.1?Ga. 相似文献
957.
958.
Lowe et al. (Estuaries and Coasts, 34:630–639, 2011) hypothesized that juvenile southern flounder Paralichthys lethostigma
(Jordan and Gilbert 1884) would migrate from the Gulf of Mexico into the Mobile-Tensaw River Delta (AL, USA) and use low-salinity
(oligohaline/freshwater) habitats during, at least, a portion of their first year of life. Thus, they analyzed the Sr/Ca ratio
profiles along the sagittal otoliths of southern flounder collected in the Mobile-Tensaw River Delta and observed that one
third of the flounders had low Sr/Ca levels in the otoliths’ core and throughout the otolith, suggesting that these fishes
hatched in freshwater or low-salinity habitats where they spend the majority of their life. The other two thirds of southern
flounder showed high levels of Sr/Ca ratio in the otoliths’ core following a marked decline of Sr/Ca ratio, which then maintained
along the remainder of the otolith. This pattern was interpreted as larvae hatched in higher salinity waters before entering
the Mobile-Tensaw River Delta; however, in this paper, I list several arguments to support an alternative interpretation for
this pattern. I suggest that the high levels of Sr/Ca ratios in the otoliths’ core of southern flounder does not reflect the
saline conditions where larvae hatched, instead it reflects the location where the female progenitor hydrated the eggs. Thus,
adding my interpretation on the data of Lowe et al. (Estuaries and Coasts, 34:630–639, 2011), it seems that southern flounder
might hatch in or near freshwater habitats and the migration of southern flounder into an estuarine ecosystem to spawn might
exist. 相似文献
959.
Y. Pousada-Ferradás S. Seoane-Labandeira A. Mora-Gutierrez A. Nú?ez-Delgado 《International Journal of Environmental Science and Technology》2012,9(1):21-29
The purpose of this work was to study the risks of water pollution due to the use of mixtures containing wood ash and sewage sludge. Mixtures including sludge and ash may be recycled as fertilizers, and they are economical as they do not integrate commercial limes, but Escherichia coli counts may keep significantly high in such mixtures, because their pH is not alkaline enough. In view of that, it seems interesting to study the E. coli survival in lixiviate from ash?Csludge mixtures including limes rather than from ash?Csludge mixtures alone. Two kinds of experiments were performed using laboratory column trials under saturated flow conditions. The first experiment investigated the chemical leaching behaviour of a mixture of 70% timber-industry wood ashes and 30% urban sewage sludge (% dry weight) at doses equivalent to 10 and 30?Mg/ha. The second experiment studied the survival of E. coli in lixiviates generated from 30?Mg/ha of a mixture consisting in 75% wood ash, 20% sewage sludge and 5% quicklime (% dry weight). In the first experiment, admixture of the ash and sludge achieved a stabilization of elements such as aluminium, iron, magnesium, nickle, carbon monoxide, cadmium, chromium and molybdenum that reduced their solubility compared with that in the ash or sludge alone. Significant solubilisation of heavy metals was not observed, with overall minor risk of chemical water pollution. In the second experiment, although including quicklime E. coli counts were still detected in the lixiviate, indicating risk of water contamination. 相似文献
960.
Jens-Olaf?DelfsEmail author Frank?Blumensaat Wenqing?Wang Peter?Krebs Olaf?Kolditz 《Environmental Earth Sciences》2012,65(5):1439-1457
This paper presents the hydrological coupling of the software framework OpenGeoSys (OGS) with the EPA Storm Water Management
Model (SWMM). Conceptual models include the Saint Venant equation for river flow, the 2D Darcy equations for confined and
unconfined groundwater flow, a two-way hydrological coupling flux in a compartment coupling approach (conductance concept),
and Lagrangian particles for solute transport in the river course. A SWMM river–OGS aquifer inter-compartment coupling flux
is examined for discharging groundwater in a systematic parameter sensitivity analysis. The parameter study involves a small
perturbation (first-order) sensitivity analysis and is performed for a synthetic test example base-by-base through a comprehensive
range of aquifer parametrizations. Through parametrization, the test cases enables to determine the leakance parameter for
simulating streambed clogging and non-ocillatory river-aquifer water exchange rates with the sequential (partitioned) coupling
scheme. The implementation is further tested with a hypothetical but realistic 1D river–2D aquifer model of the Poltva catchment,
where discharging groundwater in the upland area affects the river–aquifer coupling fluxes downstream in the river course
(propagating feedbacks). Groundwater contribution in the moving river water is numerically determined with Lagrangian particles.
A numerical experiment demonstrates that the integrated river–aquifer model is a serviceable and realistic constituent in
a complete compartment model of the Poltva catchment. 相似文献