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31.
Pan-African magmatism in the Menderes Massif: geochronological data from leucocratic tourmaline orthogneisses in western Turkey 总被引:1,自引:1,他引:0
O. E. Koralay O. Candan F. Chen C. Akal R. Oberh?nsli M. Sat?r O. ?. Dora 《International Journal of Earth Sciences》2012,101(8):2055-2081
The Menderes Massif, exposed in western Anatolia, is a metamorphic complex cropping out in the Alpine orogenic belt. The metamorphic rock succession of the Massif is made up of a Precambrian basement and overlying Paleozoic-early Tertiary cover series. The Pan-African basement is composed of late Proterozoic metasedimentary rocks consisting of partially migmatized paragneisses and conformably overlying medium- to high-grade mica schists, intruded by orthogneisses and metagabbros. Along the southern flank of the southern submassif, we recognized well-preserved primary contact relationship between biotite and leucocratic tourmaline orthogneisses and country rocks as the orthogneisses represent numerous large plutons, stocks and vein rocks intruded into a basement of garnet mica schists. Based on the radiometric data, the primary deposition age of the precursors of the country rocks, garnet mica schist, can be constrained between 600 and 550?Ma (latest Neoproterozoic). The North Africa–Arabian-Nubian Shield in the Mozambique Belt can be suggested as the possible provenance of these metaclastics. The intrusion ages of the leucocratic tourmaline orthogneisses and biotite orthogneisses were dated at 550–540?Ma (latest Neoproterozoic–earliest Cambrian) by zircon U/Pb and Pb/Pb geochronology. These granitoids represent the products of the widespread Pan-African acidic magmatic activity, which can be attributed to the closure of the Mozambique Ocean during the final collision of East and West Gondwana. Detrital zircon ages at about 550?Ma in the Paleozoic muscovite-quartz schists show that these Pan-African granitoids in the basement form the source rocks of the cover series of the Menderes Massif. 相似文献
32.
We present a new technique for the rapid, automatic identification of solar features on full-disk photometric images. The technique permits the detection of features whose contrasts are only slightly above the noise level. Contrast and contiguity criteria are used to identify pixels belonging to an individual feature. The criteria used are simple and objective, and do not require one to guess at the contrast distribution of the features. Comparison of Caii K images with magnetograms shows excellent agreement between the identified features and observed magnetic features. In addition, we can now reliably identify faculae on continuum images. Since this technique can be rapidly applied to a large set of images, it allows us to compile a database of the physical and photometric properties of individual solar features. 相似文献
33.
34.
Dr. Dora Bedlivy Dr. E. J. Llambías Lic. J. F. H. Astarloa 《Mineralogy and Petrology》1972,17(2):65-75
Zusammenfassung Rooseveltit findet sich in der Oxidationszone der Lagerstätten San Francisco de los Andes und Cerro Negro de la Aguadita, in der Provinz San Juan, Argentinien, auf 30°22 S und 69°33 W. Er bildet sehr feinkörnige, weiß-graue, nach Bismuthinit pseudomorphe Aggregate. Die Brechungsindizes liegen zwischenn=2,10 und 2,30. Die Vickershärte beträgt 513 (4–5 der Mohs'schen Härteskala). Mittels Elektronenmikrosonde wurde folgende chemische Zusammensetzung bestimmt: As=21,5±1%, Bi=60,9±2%. Rooseveltit ist monoklin mita
0=6,878(1)Å, b0=7,163(1) Å, c0=6,735(1) Å, =104° 46±1, Z=4, calc.=6,94 g·cm–3, RaumgruppeP 21/n.Rooseveltit wurde nach drei verschiedenen Methoden synthetisiert. Die Pulverdiagramme der synthetischen Produkte stimmen mit dem des Minerals überein. Die Brechungsindizes wurden mitn
=2,13(2) bzw. n=2,25(2) und die Dichte mit obs.=7,01 g·cm–3 bestimmt. Zellparameter: a0-6,882(1) Å, b0=7,164(1) Å, c0=6,734(1) Å, =104° 50,5±0,7, calc.=6,94 g·cm–3. Das synthetische Material schmilzt um 950°C. Selbst nach mehrstündigem Erhitzen auf 920°C läßt sich keine Veränderung im Pulverdiagramm des Minerals festellen.Es wird versucht, die natürliche Bildung des Rooseveltits zu erklären.
Mit 2 Abbildungen 相似文献
Rooseveltite from San Francisco de los Andes and Cerro Negro de la Aguadita, San Juan, Argentina
Summary Rooseveltite occurs in the weathering zone of the San Francisco de los Andes and Cerro Negro de la Aguadita mines, located in the San Juan Province, Argentina, at 30° 22S and 69° 33W. It appears in grey, finegrained aggregates pseudomorph after bismuthinite. Refraction index ranges fromn=2.10 to 2.30. The Vickers microhardness is 513 (4–5 of Mohs' scale). Chemical composition from electron micro probe measurements is As 21.5±1% and Bi 60.9±2%. Rooseveltite is monoclinic, with a0=6.878(1) Å, b0=7.163(1) Å, c0=6.735(1) Å, =104° 46±1, Z=4, calc.=6,94 g·cm–3, space groupP 21/n.The synthetic compound was prepared by three different methods. The powder pattern are the same as that of the mineral. Refraction index n=2.13(2) and n=2.25(2). The measured specific gravity is pobs.=7,01 g·cm–3. Cell parameters: a0=6.882(1) Å, b0=7.164(1) Å,c 0=6.734(1) Å, =104° 50.5±0.7, calc.=6,94 g·cm–3. The synthetic material melts at about 950°C. After heating to 920°C no variations were observed in the powder diagram of the mineral.It is tried to explain the formation of rooseveltite in natural environment.
Mit 2 Abbildungen 相似文献
35.
Summary Based on the French conjugate experiment of satellite and ground-based measurements of ULF signals on GEOS-1 and at Husafell,
changes of the ionospheric filter in the course of a series of measurements of intensive Pc1 micropulsations (ICW) on 1. 8.
1977 were wave diagnosticated. Changes of the vertical profile of electron concentration in the outer high-latitude ionosphere
were simulated numerically by solving approximately the inverse problem using the matrix method of numerical modelling of
ionospheric filtration in Pc1 frequencies. It was found that the intensive ICW packets could have propagated through the corridor
of the high-latitude ionospheric plasma through. Quantitative estimates of ionospheric changes, however, are usually upset
by the effects of other factors in the course of the wave's propagation through the outer magnetosphere. 相似文献
36.
Brett R. Baldwin Dora Taggart Yunzhou Chai David Wandor Anita Biernacki Kerry L. Sublette John T. Wilson Claudia Walecka‐Hutchison Camillo Coladonato Bryan Goodwin 《Ground Water Monitoring & Remediation》2017,37(2):58-70
Adaptive site management and aggressive bioremediation in the source zone of a complex chlorinated dense nonaqueous phase liquid (DNAPL) site reduced total chlorinated hydrocarbon mass discharge by nearly 80%. Successful anaerobic bioremediation of chlorinated hydrocarbons can be impaired by inadequate concentrations of electron donors, competing electron acceptors, specific inhibitors such as chloroform, and potentially by high contaminant concentrations associated with residual DNAPL. At the study site, the fractured bedrock aquifer was impacted by a mixture of chlorinated solvents and associated daughter products. Concentrations of 1,1,2,2‐tetrachloroethane (1,1,2,2‐TeCA), 1,1,2‐trichloroethane (1,1,2‐TCA), and 1,2‐dichloroethane (1,2‐DCA) were on the order of 100 to 1000 mg/L. Chloroform was present as a co‐contaminant and background sulfate concentrations were approximately 400 mg/L. Following propylene glycol injections, concentrations of organohalide‐respiring bacteria including Dehalococcoides and Dehalogenimonas spp. increased by two to three orders of magnitude across most of the source area. Statistical analysis indicated that reaching volatile fatty acid concentrations greater than 1000 mg/L and depleting sulfate to concentrations less than 50 mg/L were required to achieve a Dehalococcoides concentration greater than the 104 cells/mL recommended for generally effective reductive dechlorination. In a limited area, chloroform concentrations greater than 5 mg/L inhibited growth of Dehalococcoides populations despite the availability of electron donor and otherwise appropriate geochemical conditions. After implementing a groundwater recirculation system targeting the inhibited area, chloroform concentrations decreased permitting significant increases in concentrations of Dehalococcoides and vinyl chloride reductase gene copies. 相似文献
37.
Natural Hazards - The 2013 outbreak of smog in China triggered unprecedented public attention in the country, which played a critical role in crisis communication and management. This study... 相似文献
38.
Veronica Della Dora 《Geographical review》2015,105(2):251-255
39.
The relationship between sunspot area and other observable solar parameters, such as spectral solar irradiance or total magnetic
flux, is frequently sought by examining scatterplots of daily data, which generally show a non-linear distribution of points.
We show that the scatterplots are consistent with our published result that these observable solar parameters are related
to sunspot area by a transformation that is both linear and time invariant, namely by convolution with a finite impulse response
function. Most solar parameters are affected by extended active regions, not just by sunspots. The fact that a complex active
region evolves much more slowly than its associated sunspots provides a simple physical explanation of the observed non-linearities
in scatterplots. 相似文献
40.
Excavations in the Helike Delta on the Gulf of Corinth have brought to light architectural remains from the Early Bronze Age (EBA), Geometric, Classical, Hellenistic, Roman, and Byzantine periods. Borehole results suggest that a lagoon intermittently occupied much of the delta during the Holocene. We discovered a well‐preserved EBA settlement about 1km inland from the present shore, buried under 3 to 5m of fine sediments containing marine, brackish, and freshwater microfossils. A Classical site 130m away, buried under 3m of similar sediments, may have been destroyed by the earthquake and tsunami of 373 B.C., which submerged the city of Helike. Possible tsunami evidence is noted. Although the EBA and Classical sites were both long submerged and buried by lagoonal sediments, tectonic uplift has raised both horizons above sea level. A shallow black clay layer suggests that a marsh covered the Classical and EBA sites in Byzantine times. © 2011 Wiley Periodicals, Inc. 相似文献