Belgica 7904 meteorite (B-7904), Queen Maud Land (Dronning Maud Land), Eastern Antarctica, Antarctica
|Latitude & Longitude (WGS84):||72° 34' 59'' South , 31° 15' 0'' East|
|Latitude & Longitude (decimal):||-72.58333,31.25000|
|Köppen climate type:||EF : Ice cap climate|
Carbonaceous Chondrite, ungrouped [C2-ung; S1: W1]
Find, 1979; 1.234 kg
In 1979 a somewhat weathered meteorite with a still nearly intact fusion crust was recovered in Eastern Antarctica. The meteorite seemed to most resemble members of the CM carbonaceous chondrite class and, indeed, Belgica 7904 was listed as a CM meteorite two decades later in the Catalogue of Meteorites published in 2000. Belgica shares a number of characteristics with CM meteorites. Belgica 7904 contains moderately small chondrules rich in Olivine and other silicates, tiny crystals and mineral fragments, and a very fine-grained, microscopic and disparate mix of crystalline and glassy material rich in intertwined phyllosilicates. However, its bulk chemisty, isotopic ratios, and mineralogical features do not quite match those of the CM group or any other defined Carbonaceous Chondrite group.
At some very early epoch the moderately high temperature components found in its chondrules (e.g. Forsterite, Enstatite) were altered and partially hydrated by the admixture of new, less reduced constituents. Such phyllosilicate material, however, was once again dehydrated by later heating events (perhaps only one). Today we do not know whether Belgica 7904 is the sole terrestrial representative of an unknown homeworld or, perhaps, one of a very small subgroup. For now it is listed as one of the small number of ‘Ungrouped Carbonaceous Chondrites.’
Much of what we know about Beligica 7904 was summarized in two reviews presented two decades ago (Ikeda,1992; Kimura & Ikeda, 1992). However, intriguing details about its tiny components and microstructures are still being reported even today.
25 valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
2500 - 4000 Ma
|Archean intrusive and metamorphic terranes|
Age: Archean (2500 - 4000 Ma)
Comments: Mixtures of metamorphic and intrusive or plutonic rocks, tracts known as crystalline, migmatitic terranes, moderately to highly metamorphosed rocks of unknown origin with or without intrusions. This classification is inherently prone to variable interpretation, as other compilers might distinguish some packages by their metamorphic or gneissic protoliths, and the associated age ranges may be more variable.
Lithology: Intrusive and metamorphic terranes
Reference: Geological Survey of Canada. Generalized geological map of the world and linked databases. doi:10.4095/195142. Open File 2915d. 
Prinz, M., Weisberg, M. K., Han, R. & Zolensky, M. E. (1989). Chondrules in the B7904 C1-2 Chondrite. Abstracts and Program for the 52nd Annual Meeting of the Meteoritical Society. LPI Contribution 712, p.201. Lunar and Planetary Institute: Houston. (Aug 1989)
Prinz, M., Weisberg, M. K., Han, R. & Zolensky, M. E. (1989) Type I and II chondrules in the B7904 carbonaceous chondrite. Meteoritics 24 (4), 317-318. (Dec 1989)
Tomeoka, K. (1990). Mineralogy and petrology of Belgica-7904: A new kind of carbonaceous chondrite from Antarctica. Proceedings of the NIPR Symposium, No. 3. Yanai, K. (ed.). National Institute of Polar Research: Tokyo. pp. 40-54. (Oct 1990)
Bischoff, A. & Metzler, K. (1991). Mineralogy and petrography of the anomalous carbonaceous chondrites Yamato-86720, Yamato-82162, and Belgica-7904. Proceedings of the NIPR Symposium, No. 4. Yanai, K. (ed.). Published by the National Institute of Polar Research: Tokyo. p.226. (Mar 1991)
Ikeda, Y. (1992). An overview of the research consortium, "Antarctic carbonaceous chondrites with CI affinities, Yamato-86720, Yamato-82162, and Belgica-7904". Proc. NIPR Symp. Antarct. Meteorites 5: 49-73. (March 1992)
Kimura, M. & Ikeda, Y. (1992). Mineralogy and Petrology of an unusual Belgica-7904 Carbonaceous Chondrite: Genetic Relationships among the Components. Proc. NIPR Symp. Antarct. Meteorites 5: 74-119. (March 1992)
Brearley, A. J. & Jones, R. H. (1998): Chondritic Meteorites. In: Planetary Materials (Papike, J. J., Editor): Chapter 3, 398 pages. Mineralogical Society of America: Washington, DC, USA. (1998)
Grady, M. M. (2000). Catalogue of Meteorites (5/e). Cambridge University Press: Cambridge, New York, Oakleigh, Madrid, Cape Town.
Choe, W. H. et al., (2010). Compositions and taxonomy of 15 unusual carbonaceous chondrites. Meteoritics and Planetary Science 45 (4): 531-554. (April 2010)
Harries, D. & Langenhorst, F. (2013) The nanoscale mineralogy of Fe,Ni sulfides in pristine and metamorphosed CM and CM/CI-like chondrites: Tapping a petrogenetic record. Meteoritics & Planetary Science 48 (5): 879-903. (May 2013)