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| Hekinian, Roger; Cheminee, J; Dubois, J; Stoffers, P; Scott, S; Guivel, C; Garbe Schonberg, D; Devey, C; Bourdon, B; Lackschewitz, K; Mcmmurtry, G; Le Drezen, Eliane. |
| Multibeam bathymetry and bottom imaging (Simrad EM12D) studies on an area of about 9500 km(2) were conducted over the Pitcairn hotspot near 25degrees10'S, 129degrees 20'W In addition, 15 dives with the Nautile submersible enabled us to obtain ground-true observations and to sample volcanic structures on the ancient ocean crust of the Farallon Plate at 3500-4300 in depths. More than 100 submarine volcanoes overprint the ancient crust and are divided according to their size into large ( > 2000 in in height), intermediate (500-2000 in high) and small ( < 500 in high) edifices. The interpretation of seafloor backscatter imagery accompanied by submersible observations and sampling enabled us to infer that the total volume of submarine lava erupted during... |
| Tipo: Text |
Palavras-chave: Petrology; Volcanic sequences; Morphology; Volcanism; Hotspot. |
| Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/2003/publication-784.pdf |
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| Zwaan, J.C.. |
| As one of the most valuable gemstones, emeralds are known to occur in several countries of the world, such as Colombia, Zambia, Brazil, Pakistan, Afghanistan, Russia, Madagascar and Zimbabwe. The emerald deposits at Sandawana, Zimbabwe, are described, the emeralds from this deposit characterised and a model of emerald formation presented; this is compared with existing models. The emeralds from Sandawana, Zimbabwe, show relatively constant physical properties, with high refractive indices and specific gravities. They are characterized by laths and fibres of amphibole, both actinolite and cummingtonite. Other common inclusions are albite and apatite. Rare, opaque and chromium-rich inclusions constitute a new variety of ilmenorutile. Compared to emeralds... |
| Tipo: Article / Letter to the editor |
Palavras-chave: Emerald; Sandawana; Zimbabwe; Gemmology; Petrology; Geothermometry; Geochronology; 38.30. |
| Ano: 2006 |
URL: http://www.repository.naturalis.nl/record/209632 |
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| Kriegsman, L.M.. |
| Petrological collections result from sampling for academic research, for aesthetic or commercial reasons, and to document natural diversity. Selection criteria for reducing and enhancing collections include adequate documentation, potential for future use, information density, time and money invested in specimens, and spatial and financial constraints. Application of these criteria to the voluminous (c. 300,000 samples) rock collections of the University of Amsterdam, led to partial acquisition by the Nationaal Natuurhistorisch Museum in Leiden (Naturalis) late in 2002. Selected items included: (i) historical collections; (ii) material from former overseas domains; (iii) material from poorly accessible areas; (iv) material useful for research at the museum... |
| Tipo: Article / Letter to the editor |
Palavras-chave: Geology; Petrology; Collections; Selection; De-selection; De-accessioning; 38.25. |
| Ano: 2004 |
URL: http://www.repository.naturalis.nl/record/215464 |
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