The water content and parental magma of the second chassignite NWA 2737: Clues from trapped melt inclusions in olivine
Article first published online: 19 FEB 2013
© The Meteoritical Society, 2013.
Meteoritics & Planetary Science
Volume 48, Issue 3, pages 474–492, March 2013
How to Cite
He, Q., Xiao, L., Hsu, W., BALTA, J. B., McSween, H. Y. and Liu, Y. (2013), The water content and parental magma of the second chassignite NWA 2737: Clues from trapped melt inclusions in olivine. Meteoritics & Planetary Science, 48: 474–492. doi: 10.1111/maps.12073
- Issue published online: 18 MAR 2013
- Article first published online: 19 FEB 2013
- Manuscript Accepted: 18 DEC 2012
- Manuscript Received: 20 JUN 2012
- Natural Science Foundation of China. Grant Numbers: 41072045, 41173076, 41273079
- Doctoral Fund of Ministry of Education of China. Grant Number: 20090145110001
- Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry. Grant Number: 2010012009
- Minor Planet Foundation of China
NWA 2737, the second known chassignite, mainly consists of cumulate olivine crystals of homogeneous composition (Fo = 78.7 ± 0.9). These brown colored olivine grains exhibit two sets of perpendicular planar defects due to shock. Two forms of trapped liquids, interstitial melts and magmatic inclusions, have been examined. Mineral assemblages within the olivine-hosted magmatic inclusions include low-Ca pyroxene, augite, kaersutite, fluorapatite, biotite, chromite, sulfide, and feldspathic glass. The reconstructed parental magma composition (A#) of the NWA 2737 is basaltic and resembles both the experimentally constrained parental melt composition of chassiginites and the Gusev basalt Humphrey, albeit with lower Al contents. A# also broadly resembles the average of shergottite parent magmas or LAR 06319. However, we suggest that the mantle source for the chassignite parental magmas was distinct from that of the shergottite meteorites, particularly in CaO/Al2O3 ratio. In addition, based on the analysis of the volatile contents of kaersutite, we derived a water content of 0.48–0.67 wt% for the parental melt. Finally, our MELTS calculations suggest that moderate pressure (approximately 6.8 kb) came closest to reproducing the crystallized melt-inclusion assemblages.