The University of Arizona

The Jiddat al Harasis 073 strewn field, Sultanate of Oman

E. GNOS, S. LORENZETTI, O. EUGSTER, A. J. T. JULL, B. A. HOFMANN, A. AL-KATHIRI, M. EGGIMANN

Abstract


The recently discovered Jiddat al Harasis (JaH) 073 strewn field is the largest found so far in the Sultanate of Oman, covering an area of 19 6 km. The 3463 single stones collected range in weight from 52.2 kg down to <1 g (total weight 600.8 kg) and show a pronounced mass sorting. The strewn field shape can be approximated by a NW-SE-oriented ellipsoid, indicating an atmospheric entry from SE at a low angle relative to the surface. The meteorite belongs to the L6 ordinary chondrite group and shows S4 average shock grade. Smaller stones generally show a higher weathering grade resulting in a spread from W2 and W4. Enhanced weathering of the stones causing fragmentation after the fall is observed in sandy depressions. Five 14C measurements on stones of variable size and weathering grade yielded 14C from 3.8 to 49.9 dpm/kg. Three samples give a 14C/ 10Be age consistent with about 14.4 ka. For two samples the cosmogenic, trapped, and radiogenic noble gases were measured. The ratio of the 4He and 40Ar gas retention ages of 0.29 ±  0.10 and that of the 3He and 21Ne cosmic ray exposure ages of 0.36 ±  0.08 Ma indicate that JaH 073 experienced a complex exposure history and lost 4He and 40Ar due to a major collision. Fragmentation statistics indicate a single major atmospheric disruption and an originally relatively spherical shape of the object. Assuming the material collected represents the majority of fallen mass, and 90-99% of the original weight was lost by ablation, the pre-atmospheric minimum radius of the meteoroid with density 3.4 g cm^(-3) would have been at least 75 cm.

Keywords


JaH 073;Strewn field;radionuclides;Oman

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