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1.
Summary The Aguablanca Ni-Cu-(PGE) magmatic sulphide deposit is associated with a magmatic breccia located in the northern part of
the Aguablanca gabbro (SW, Iberia). Three types of ores are present: semi-massive, disseminated, and chalcopyrite-rich veined
ore. The principal ore minerals are pyrrhotite, pentlandite and chalcopyrite. A relatively abundant platinum-group mineral
(PGM) assemblage is present and includes merenskyite, melonite, michenerite, moncheite and sperrylite. Moreover, concentrations
of base and precious metals and micro-PIXE analyses were obtained for the three ore-types. The mineralogy and the mantle-normalised
chalcophile element profiles strongly suggest that semi-massive ore represents mss crystallisation, whereas the disseminated ore represents an unfractionated sulphide liquid and the chalcopyrite-rich veined
ore a Cu-rich sulphide liquid. Palladium-bearing minerals occur commonly enclosed within sulphides, indicating a magmatic
origin rather than hydrothermal. The occurrences and the composition of these minerals suggest that Pd was initially dissolved
in the sulphides and subsequently exsolved at low temperatures to form bismutotellurides. Negative Pt and Au anomalies in
the mantle-normalised chalcophile element profiles, a lack of Cu-S correlation and textural observations (such as sperrylite
losing its euhedral shape when in contact with altered minerals) suggest partial remobilisation of Pt, Au and Cu by postmagmatic
hydrothermal fluids after the sulphide crystallisation.
Authors’ addresses: R. Pi?a, L. Ortega, R. Lunar, Departamento de Cristalografía y Mineralogía, Facultad de Geología, Universidad Complutense de Madrid, ES-28040 Madrid,
Spain; F. Gervilla, Facultad de Ciencias, Instituto Andaluz de Ciencias de la Tierra, Universidad de Granada-CSIC, Avda. Fuentenueva, s/n, ES-18002
Granada, Spain 相似文献
2.
Periodic orbits in the Stormer problem are studied using the symmetry lines of the Poincaré map introduced by De Vogelaere. Many known facts are explained by mean of these lines. The dynamics of four special symmetry lines when the Stormer parameter 1 changes is presented, and we obtain a clear global view of the structure of the simple periodic orbits and their bifurcations, including the asymmetrical ones. New asymmetrical multiple periodic orbits are obtained. 相似文献
3.
4.
Pi Zhenbang Liu Zhuoqin Yang Chao Tian Xike Fei Jinbo Zheng Jianhua 《Frontiers of Earth Science》2007,1(1):26-29
A type of exfoliated kaolinite was produced by urea-intercalation and original microwave irradiation assisted method. The
product was investigated by Fourier transformation infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electronic
microscopy (SEM), Brunauer-Emmett-Teller (BET) and laser particle analysis techniques. FT-IR spectra show that NHCO molecule
exists in the intercalated kaolinite. XRD analyses indicate that the kaolinite sheet-like structure was disordered after microwave
irradiation. The urea decomposition process and explosion effect between the sheet-like structures of kaolinite under microwave
irradiation were discussed. The SEM and BET analyses reveal that the end product is exfoliated kaolinite with thin particles
and increased surface area. Size and zeta potential analyses show that the particle size distribution is between 250 nm and
550 nm with normal distribution and the particle is negatively charged. In comparison with the conventional grind method,
the process adopted appears to be economic and the exfoliated kaolinite end product may display a significantly enhanced performance
in industrial applications. 相似文献
5.
6.
Wang Minfang Zhang Xubo Guo Xiaonan Pi Daohui Yang Meijun 《Mineralogy and Petrology》2018,112(1):85-103
Mineralogy and Petrology - Electron probe microanalysis (EPMA) results are reported for newly identified silver–bearing minerals from the Xinhua deposit, Yunkaidashan area, South China. The... 相似文献
7.
The Five-hundred-meter Aperture Spherical radio Telescope(FAST) will make contributions to studies of Galactic and extragalactic masers. This telescope, with construction finished and now undergoing commissioning, has an innovative design that leads to the highest sensitivity of any single dish radio telescope in the world. FAST's potential for OH megamaser research is discussed, including the sky density of masers detectable in surveys. The scientific impact expected from FAST maser studies is also discussed. 相似文献
8.
Olivier J. Hardy Céline Born Katarina Budde Kasso Daïnou Gilles Dauby Jérôme Duminil Eben-Ezer B.K. Ewédjé Céline Gomez Myriam Heuertz Guillaume K. Koffi Andrew J. Lowe Claire Micheneau Dyana Ndiade-Bourobou Rosalía Piñeiro Valérie Poncet 《Comptes Rendus Geoscience》2013,345(7-8):284-296
The biogeographic history of the African rain forests has been contentious. Phylogeography, the study of the geographic distribution of genetic lineages within species, can highlight the signatures of historical events affecting the demography and distribution of species (i.e. population fragmentation or size changes, range expansion/contraction) and, thereby, the ecosystems they belong to. The accumulation of recent data for African rain forests now enables a first biogeographic synthesis for the region. In this review, we explain which phylogeographic patterns are expected under different scenarios of past demographic change, and we give an overview of the patterns detected in African rain forest trees to discuss whether they support alternative hypotheses regarding the history of the African rain forest cover. The major genetic discontinuities in the region support the role of refugia during climatic oscillations, though not necessarily following the classically proposed scenarios. We identify in particular a genetic split between the North and the South of the Lower Guinean region. Finally we provide some perspectives for future study. 相似文献
9.