DHOFAR 1988


C2-ungrouped
Possible 'CY' chondrite
(thermally metamorphosed/dehydrated)

standby for dhofar 1988 photo
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Found December 2, 2011
19° 4.865' N., 54° 46.026' E.

A relatively fresh, partially crusted carbonaceous chondrite weighing 59 g was found in the Dhofar desert region of Oman by M. Cimala and L. Smula (see in situ photos below). A sample was sent for analysis to the Natural History Museum in Berlin (A. Greshake) and the University of New Mexico (oxygen isotopes; K. Ziegler), and Dhofar 1988 was classified as C2-ungrouped.

standby for dhofar 1988 in situ photo
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Photos courtesy of Marcin Cimala

Dhofar 1988 and three other possibly paired brecciated meteorites were found within 3 km of each other (see Google Earth image below). These include the anomalous CM chondrite Dhofar 735 (oxygen isotope plot; photo courtesy of Thomas Witzke), the CM2 chondrite Dhofar 955, and the ungrouped carbonaceous chondrite Dhofar 2066 (oxygen isotope plot; photo courtesy of Lukasz Smula).

Google Earth Image of Dhofar Region, Oman

Dhof 735 (2002) 381 g: 19° 4.1' N, 54° 46.8' E

Dhof 955 (2003) 16 g: 19° 3.3' N, 54° 45.2' E

Dhof 2066 (2010) 13 g: 19° 3.728' N, 54° 44.665' E

Dhof 1988 (2011) 59 g: 19° 4.865' N, 54° 46.026' E

Coordinates from MetBull

Dhofar 1988 has an O-isotopic composition that is enriched in heavy oxygen (18O, 17O), and has a plot very close to the C2-ungrouped Tagish Lake (oxygen isotope plot) and to the CM/CI-like, thermally metamorphosed/dehydrated Antarctic meteorite group termed ‘CY’ by Y. Ikeda (1992 [Consortium Summary]) which consists of Belgica 7904 (C2-ung), Y-82162 (C1/2-ung), Y-86029 (CI1), Y-86720 (C2-ung), Y-86789 (C2-ung, likely paired with Y-86720), and Y-980115 (CI1); see the MetBull oxygen isotope plot and diagrams below.

standby for cy group ox diagram
Diagram credit: King and Russell, 50th LPSC, #1386 (2019)
See also open access article by King et al. in Chemie der Erde–Geochemistry, vol. 79 (2019)

standby for dhofar 225 oxygen isotope diagram
Diagram credit: Greenwood et al., GCA, vol. 277, p. 381 (2020, open access link)
'Linking asteroids and meteorites to the primordial planetesimal population'
(https://doi.org/10.1016/j.gca.2020.02.004)

Other possibly related dehydrated CM-like meteorites include WIS 91600 (CM2.2 [CI]), EET 96010 (CM2), and PCA 02012 (CM2). In addition, Nakamura (2006) identified two regolith breccias, Y-793321 (CM2) and A-881458 (CM2), that contain solar-wind-implanted noble gases and belong to this dehydrated group, while M.M.M. Meier (2014) found that the meteorite Diepenveen (CM2-an) also contains similar trapped solar gases. Both Y-86737 and Y-980134, which are classified as CI1, have similar oxygen isotopes (King and Russell, 2019). Notably, The CM-an Dhofar 225 has many features and an oxygen isotopic composition like Dhofar 735, which along with Belgica 7904, Y-86720, and PCA 02012 have experienced the highest temperatures (~900°C) over a brief time interval (PCA 02012 estimated at tens of hours; Nakato et al., 2013) compared to other members of the CY group.

Further information about the thermally metamorphosed CM-like chondrites and the proposed CY group can be found on the Dhofar 225 page. The specimen of Dhofar 1988 shown above and below is a 2.73 g slice.

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Photos courtesy of Marcin Cimala—PolandMET