Trapped nitrogen in individual chondrules: Nature of chondrule precursors and clues to formation mechanisms

Abstract

[1] Nitrogen amount and isotopic composition have been measured in individual chondrules of six ordinary chondrites (OC) and two each of carbonaceous (CC) and enstatite chondrites (EC N of the chondrules, we propose the presence of at least three N components carried by phase Q, presolar diamonds (HL), and insoluble organic matter (IOM). The precursors of chondrules from OC and CC are different than the bulk OC and CC, which represents the different environment for their formation, compared to the bulk OC and CC. However, for EC chondrules, precursors as well as the formation environment are the same as those of enstatite chondrites.

Cosmogenic and trapped noble gases in individual chondrules: Clues to chondrule formation

“…Textures, types and major element composition of relevance are given in Table A3. Detailed elemental compositions of each chondrule are given in our recent publication (Table 2, Das and Murty 2009). …”

“…This chondrule has about 140 micron thick rim of metal (Fig. 1, Das and Murty 2009), which probably represents solidified coating of metal crystallized before it could escape.…”

“…For chondrules >1 mg, we took splits and determined the target chemical composition using EPMA. Details on the chemical characterization method and chemical composition of chondrule are published earlier (Das and Murty 2009). Textures, types and major target elements (used for calculation of production rates) in chondrules are listed in Table A3.…”

“…All the samples were from the meteorite collection of Physical Research Laboratory, Ahmedabad. Details of chondrule separation are given in an earlier publication (Das and Murty 2009). Briefly, for meteorites (ex.…”

“…The chemical composition of chondrule is needed for the calculation of cosmogenic noble gas production rates. A total of 26 chondrules have been characterized chemically (Das and Murty 2009). Chondrules have been classified into Type I (13) and Type II (13) based on their FeO content as suggested by McSween (1977) and Scott and Taylor (1983).…”