Carbon,hydrogen, and oxygen isotope studies of the regional metamorphic complex at Naxos,Greece     

Robert O. Rye  Roelof D. Schuiling  Danny M. Rye  J.Ben H. Jansen 《Geochimica et cosmochimica acta》1976,40(9):1031-1049

At Naxos, Greece, a migmatite dome is surrounded by schists and marbles of decreasing metamorphic grade. Sillimanite, kyanite, biotite, chlorite, and glaucophane zones are recognized at successively greater distances from the migmatite dome. Quartz-muscovite and quartz-biotite oxygen isotope and mineralogie temperatures range from 350 to 700°C.The metamorphic complex can be divided into multiple schist-rich (including migmatites) and marblerich zones. The δ¹⁸O values of silicate minerals in migmatite and schist units and quartz segregations in the schist-rich zones decrease with increase in metamorphic grades. The calculated δ¹⁸O_H2O values of the metamorphic fluids in the schist-rich zones decrease from about 15‰ in the lower grades to an average of about 8.5‰ in the migmatite.The δD values of OH-minerals (muscovite, biotite, chlorite, and glaucophane) in the schist-rich zones also decrease with increase in grade. The calculated δD_H2O values for the metamorphic fluid decrease from ?5‰ in the glaucophane zone to an average of about ?70‰ in the migmatite. The δD values of water in fluid inclusions in quartz segregations in the higher grade rocks are consistent with this trend.Theδ¹⁸O values of silicate minerals and quartz segregations in marble-rich zones are usually very large and were controlled by exchange with the adjacent marbles. The δD values of the OH minerals in some marble-rich zones may reflect the value of water contained in the rocks prior to metamorphism.Detailed data on 20 marble units show systematic variations of δ¹⁸O values which depend upon metamorphic grade. Below the 540°C isograd very steep δ¹⁸O gradients at the margins and large δ¹⁸O values in the interior of the marbles indicate that oxygen isotope exchange with the adjacent schist units was usually limited to the margins of the marbles with more exchange occurring in the stratigraphic bottom than in the top margins. Above the 540°C isograd lower δ¹⁸O values occur in the interior of the marble units reflecting a greater degree of recrystallization and the occurrence of Ca-Mg-silicates.Almost all the δ¹³C values of the marbles are in the range of unaltered marine limestones. Nevertheless, the δ¹³C values of most marble units show a general correlation with δ¹⁸O values.The $\text{CO}{}_2\text{H}{}_2\text{O}$ mole ratio of fluid inclusions in quartz segregations range from 0.01 to 2. Theδ¹³C values of the CO₂ range from ?8.0 to 3.6‰ and indicate that at some localities CO₂ in the metamorphic fluid was not in carbon isotopic equilibrium with the marbles.  相似文献   

Zircon U-Pb ages of the Franzfontein granitic suite,northern South West Africa     

A.J. Burger  T.N. Clifford  R.McG. Miller 《Precambrian Research》1976,3(5):415-431

U-Pb isotopic data are presented for composite and size fractions of zircons from 15 samples of the Franzfontein granitic suite. These data reveal two distinctly different discordance trends that yield concordia intercept ages of 1730±30 m.y. and 1870±30 m.y. that are believed to encompass the age of emplacement of the suite. The previously published Rb-Sr isochron age of 1580±20 m.y. is now interpreted as recording a time of Rb and/or Sr migration through the system. The stratigraphic implications of the new zircon data are discussed.  相似文献   

Kaolin-Kohlentonsteine im flözführenden Oberkarbon des Niederrheinisch-Westfälischen Steinkohlenreviers     

Dr. rer. nat. h. c. Kurt Burger 《International Journal of Earth Sciences》1980,69(2):488-531

Starting from general considerations of the rocks existing in the Ruhr Carboniferous and the mineral layers in coal seams, an informative review is given about the definition of clay stones and kaolin coal tonsteins as well as about the stratigraphic distribution of key horizons with special regard to the kaolin coal tonsteins. Information follows about the first evidence of individual kaolin coal tonsteins, their existence in the normal geologic columns and more recent stratigraphic sections as well as about the concentration of repositories. Besides, the kaolin coal tonsteins are characterized according to their macroscopic and microscopic external form. The paper reports about their material constituents (mineral components, trace elements, anorganic chemical constituents and organic substances in form of coal hydrates and amino acids). The paper closes with some statements about the importance and utilization of kaolin coal tonsteins to solve local and regional duties in mining geology.  相似文献   

Zur Inaktivierung von Erregern übertragbarer Krankheiten in Gewässern     

G. Burger 《洁净——土壤、空气、水》1990,18(6):667-671

Germs of infectious diseases are not adapted to the environment of waters but to their hosts. Therefore, as allochthonous elements they survive there only for a short time for the most part; individual germs, however, are much more resistant under these environmental conditions, in dependence on their species or type. At a higher initial germ content the period of survival in general is longer than at a lower one. For inactivation in waters e.g. the following causes may be responsible: nutrient deficiency, unfavourable water temperature, redox potential, saprobity, chemical constituents, including metabolic products of aquatic organisms, solar light osmotic pressure, settling material and suspended solids, bacteriophages.  相似文献   

The stellar populations of spiral galaxies     

Eric F. Bell  Roelof S. de Jong † 《Monthly notices of the Royal Astronomical Society》2000,312(3):497-520

We have used a large sample of low-inclination spiral galaxies with radially resolved optical and near-infrared photometry to investigate trends in star formation history with radius as a function of galaxy structural parameters. A maximum-likelihood method was used to match all the available photometry of our sample to the colours predicted by stellar population synthesis models. The use of simplistic star formation histories, uncertainties in the stellar population models and considering the importance of dust all compromise the absolute ages and metallicities derived in this work; however, our conclusions are robust in a relative sense. We find that most spiral galaxies have stellar population gradients, in the sense that their inner regions are older and more metal rich than their outer regions. Our main conclusion is that the surface density of a galaxy drives its star formation history, perhaps through a local density dependence in the star formation law. The mass of a galaxy is a less important parameter; the age of a galaxy is relatively unaffected by its mass; however, the metallicity of galaxies depends on both surface density and mass. This suggests that galaxy‐mass-dependent feedback is an important process in the chemical evolution of galaxies. In addition, there is significant cosmic scatter suggesting that mass and density may not be the only parameters affecting the star formation history of a galaxy.  相似文献   

川南须家河组第四段TONSTEINS的岩石地化特征     

Kuet Burger  任友谅  周义平 《煤田地质与勘探》2000,28(2):1-5,T001

对四川南部上三叠统须家河组第４段（Ｔ３ｘｊ＾４）中的５层ＴＯＮＳＴＥＩＮＳ做了较详细的岩石学、地球化学研究。结果表明,它们都是同沉积的酸性火山灰,在泥炭沼泽环境下,经过水解和后期成岩作用,转变成质地较纯的高岭石粘土岩。ＴＯＮＳＴＥＩＮＳ的岩石结构类型较简单,以致密型和团粒－致密型为主,结晶型较少。同层ＴＯＮＳＴＥＩＮ的岩石结构的某些亲石元素含量及组合关系在较大范围内保持稳定,并具有显著的标志性;Ｔ  相似文献   

A comment on the detection of closed magnetic structures in the solar wind     

J. T. Gosling  E. C. Roelof 《Solar physics》1974,39(2):405-408

It has recently been suggested that the large scale structure of the interplanetary magnetic field can be deduced solely from solar wind speed measurements. Here it is emphasized that, in addition to speed measurements, direct measurements of the interplanetary field and indirect diagnostics such as measurements of the solar wind kinetic temperature and galactic and solar energetic particle modulations and anisotropics are required to distinguish between open and closed magnetic structures in the solar wind.The National Center for Atmospheric Research is sponsored by the National Science Foundation.  相似文献   

The copper deposits of the O'okiep District,South Africa: New data and concepts     

E. F. Stumpfl  T. N. Clifford  A. J. Burger  D. van Zyl 《Mineralium Deposita》1976,11(1):46-70

The copper deposits of the O'okiep District rank amongst the top three S. African producers, with an annual output of 3 million metric tons grading 1.65% Cu on average. They occur in what is now considered the S. extension of the 1200 m. y. Kibaran orogenic belt. Copper mineralization is linked to cross-cutting bodies of "noritoid" R_O=0.7126–0.7250) which have been emplaced into the granulite facies metamorphic country rocks 1100 m. y. ago. The results of 150 electron probe analyses show that orthopyroxene in the non-ore-bearing noritoids is En_51–52, in the ore-bearing noritoids En_60–65. There is a concomitant variation in the composition of phlogopitic mica which carries higher Fe in non-ore-bearing noritoids. The Ticontents of magnetite are below 0.1%; there are significant chromium values. Spinel exsolution lamellae contain up to 14% ZnO. The copper sulphides occur as granular aggregates with silicates, on grain boundaries and on cleavage planes of hypersthene and mica; they also replace altered Fe-Ti-oxides. Pyrite (up to 1.4% Co) and pentlandite (up to 5% Co) are not widespread. The possible derivation of the noritoids from a reservoir of basic magma at depth is considered. A source-bed model, involving generation of noritoid "magma" from Cu-bearing members of the stratigraphic sequence, during the peak of metamorphism (800–1000 °C, 6–8 kb) is tentatively proposed. Stratabound base metal concentrations (Aggeneys, Gamsberg) in lower grade (amphibolite facies) metamorphic terrains to the East have not been mobilized.formerly, Mineralogisch-Petrographisches Institut, Universität Hamburg  相似文献   

Succession and productivity on perturbed and naturalSpartina salt-marsh areas in New Jersey     

Joanna Burger  Joseph Shisler 《Estuaries and Coasts》1983,6(1):50-56

Vegetation growth on spoil placed on aSpartina patens andS. alterniflora marsh in Barnegat Bay, New Jersey, was examined for two years following spoil deposition. In areas where spoil was leveled to match the elevation of the marsh, the percent cover by the end of the first growing season ranged from 60 to 90%. By the second year, cover was 100% in all study plots. Even during the first year, there was no difference in species diversity or vegetation species in the experimental and control areas. The percentage of shrubs did not increase on the perturbed (spoil) areas compared to the control plots. During the first year, but not the second, live and dead biomass was greater in the perturbed areas compared to the control plots. In an area where the spoil was thicker succession was exceedingly slow and there was only about 5% grass cover by the end of the first growing season. BecauseSpartina colonizes primarily by rhizome growth, the comparatively slow recovery was attributed to the inability of the grass to penetrate the thick spoil layer.  相似文献   

The origin of young mare basalts inferred from lunar meteorites Northwest Africa 4734, 032, and LaPaz Icefield 02205     

Stephen M. Elardo  Charles K. Shearer Jr.  Amy L. Fagan  Lars E. Borg  Amy M. Gaffney  Paul V. Burger  Clive R. Neal  Vera A. Fernandes  Francis M. McCubbin 《Meteoritics & planetary science》2014,49(2):261-291

Northwest Africa (NWA) 4734 is an unbrecciated basaltic lunar meteorite that is nearly identical in chemical composition to basaltic lunar meteorites NWA 032 and LaPaz Icefield (LAP) 02205. We have conducted a geochemical, petrologic, mineralogic, and Sm‐Nd, Rb‐Sr, and Ar‐Ar isotopic study of these meteorites to constrain their petrologic relationships and the origin of young mare basalts. NWA 4734 is a low‐Ti mare basalt with a low Mg* (36.5) and elevated abundances of incompatible trace elements (e.g., 2.00 ppm Th). The Sm‐Nd isotope system dates NWA 4734 with an isochron age of 3024 ± 27 Ma, an initial ε_Nd of +0.88 ± 0.20, and a source region ¹⁴⁷Sm/¹⁴⁴Nd of 0.201 ± 0.001. The crystallization age of NWA 4734 is concordant with those of LAP 02205 and NWA 032. NWA 4734 and LAP 02205 have very similar bulk compositions, mineral compositions, textures, and ages. Their source region ¹⁴⁷Sm/¹⁴⁴Nd values indicate that they are derived from similar, but distinct, source materials. They probably do not sample the same lava flow, but rather are similarly sourced, but isotopically distinct, lavas that probably originate from the same volcanic complex. They may have experienced slightly different assimilation histories in route to eruption, but can be source‐crater paired. NWA 032 remains enigmatic, as its source region ¹⁴⁷Sm/¹⁴⁴Nd definitively precludes a simple relationship with NWA 4734 and LAP 02205, despite a similar bulk composition. Their high Ti/Sm, low (La/Yb)_N, and Cl‐poor apatite compositions rule out the direct involvement of KREEP. Rather, they are consistent with low‐degree partial melting of late‐formed LMO cumulates, and indicate that the geochemical characteristics attributed to urKREEP are not unique to that reservoir. These and other basaltic meteorites indicate that the youngest mare basalts originate from multiple sources, and suggest that KREEP is not a prerequisite for the most recent known melting in the Moon.  相似文献