Sisodia, M. S. ; Shukla, A. D. ; Suthar, K. M. ; Mahajan, R. R. ; Murty, S. V. S. ; Shukla, P. N. ; Bhandari, N. ; Natarajan, R. (2001) The Lohawat Howardite: mineralogy, chemistry and cosmogenic effects Meteoritics & Planetary Science, 36 (11). pp. 1457-1466. ISSN 1086-9379
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Official URL: http://www3.interscience.wiley.com/journal/1232725...
Related URL: http://dx.doi.org/10.1111/j.1945-5100.2001.tb01838.x
Abstract
The Lohawat meteorite is a texturally heterogeneous breccia having a variety of mineral and lithic fragments. Among mineral fragments, pyroxenes show a wide range of composition (Wo0.011-0.17En0.37-0.78Fs0.21-0.60) whereas plagioclase is anorthitic (An0.92Ab0.07Or0.007). Abundant rounded "chondrule-like" objects ranging in size up to ∼7 mm, some with concentric layering, have been observed. Petrographic features, trace element composition and rare earth element patterns show the presence of eucritic and diogenitic components confirming that it is a typical howardite. Cosmogenic tracks, rare gases (He, Ne, and Ar) and radionuclides (22Na and 26Al) were measured. Track density in olivine and plagioclase varies between 0.7 to 6 times 106/cm2. 38Ar exposure age is estimated to be ∼ 110 Ma, being the highest among howardites. The track production rates correspond to ablation of 9 to 15 cm, implying a radius for its preatmospheric size of ∼27 cm. 22Na/26Al ∼1, as expected from the production models and solar modulation of galactic cosmic-ray fluxes before its fall, suggesting that the meteoroid did not undergo any fragmentation during the past ∼2 Ma in interplanetary space. The radiogenic age based on K-Ar method is 4.3 Ga while the U-Th-4He age is 3.3 Ga indicating partial loss of He.
Item Type: | Article |
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Source: | Copyright of this article belongs to University of Arizona. |
ID Code: | 18550 |
Deposited On: | 17 Nov 2010 09:25 |
Last Modified: | 17 May 2016 03:15 |
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