Fine‐grained precursors dominate the micrometeorite flux
Abstract– We optically classified 5682 micrometeorites (MMs) from the 2000 South Pole collection into textural classes, imaged 2458 of these MMs with a scanning electron microscope, and made 200 elemental and eight isotopic measurements on those with unusual textures or relict phases. As textures pr...
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crwiley:10.1111/j.1945-5100.2011.01292.x 2024-09-30T14:43:47+00:00 Fine‐grained precursors dominate the micrometeorite flux TAYLOR, Susan MATRAJT, Graciela GUAN, Yunbin 2011 http://dx.doi.org/10.1111/j.1945-5100.2011.01292.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1945-5100.2011.01292.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1945-5100.2011.01292.x en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Meteoritics & Planetary Science volume 47, issue 4, page 550-564 ISSN 1086-9379 1945-5100 journal-article 2011 crwiley https://doi.org/10.1111/j.1945-5100.2011.01292.x 2024-09-19T04:19:15Z Abstract– We optically classified 5682 micrometeorites (MMs) from the 2000 South Pole collection into textural classes, imaged 2458 of these MMs with a scanning electron microscope, and made 200 elemental and eight isotopic measurements on those with unusual textures or relict phases. As textures provide information on both degree of heating and composition of MMs, we developed textural sequences that illustrate how fine‐grained, coarse‐grained, and single mineral MMs change with increased heating. We used this information to determine the percentage of matrix dominated to mineral dominated precursor materials (precursors) that produced the MMs. We find that at least 75% of the MMs in the collection derived from fine‐grained precursors with compositions similar to CI and CM meteorites and consistent with dynamical models that indicate 85% of the mass influx of small particles to Earth comes from Jupiter family comets. A lower limit for ordinary chondrites is estimated at 2–8% based on MMs that contain Na‐bearing plagioclase relicts. Less than 1% of the MMs have achondritic compositions, CAI components, or recognizable chondrules. Single mineral MMs often have magnetite zones around their peripheries. We measured their isotopic compositions to determine if the magnetite zones demarcate the volume affected by atmospheric exchange during entry heating. Because we see little gradient in isotopic composition in the olivines, we conclude that the magnetites are a visual marker that allows us to select and analyze areas not affected by atmospheric exchange. Similar magnetite zones are seen in some olivine and pyroxene relict grains contained within MMs. Article in Journal/Newspaper South pole Wiley Online Library South Pole Jupiter ENVELOPE(101.133,101.133,-66.117,-66.117) Meteoritics & Planetary Science 47 4 550 564 |
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Open Polar |
collection |
Wiley Online Library |
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crwiley |
language |
English |
description |
Abstract– We optically classified 5682 micrometeorites (MMs) from the 2000 South Pole collection into textural classes, imaged 2458 of these MMs with a scanning electron microscope, and made 200 elemental and eight isotopic measurements on those with unusual textures or relict phases. As textures provide information on both degree of heating and composition of MMs, we developed textural sequences that illustrate how fine‐grained, coarse‐grained, and single mineral MMs change with increased heating. We used this information to determine the percentage of matrix dominated to mineral dominated precursor materials (precursors) that produced the MMs. We find that at least 75% of the MMs in the collection derived from fine‐grained precursors with compositions similar to CI and CM meteorites and consistent with dynamical models that indicate 85% of the mass influx of small particles to Earth comes from Jupiter family comets. A lower limit for ordinary chondrites is estimated at 2–8% based on MMs that contain Na‐bearing plagioclase relicts. Less than 1% of the MMs have achondritic compositions, CAI components, or recognizable chondrules. Single mineral MMs often have magnetite zones around their peripheries. We measured their isotopic compositions to determine if the magnetite zones demarcate the volume affected by atmospheric exchange during entry heating. Because we see little gradient in isotopic composition in the olivines, we conclude that the magnetites are a visual marker that allows us to select and analyze areas not affected by atmospheric exchange. Similar magnetite zones are seen in some olivine and pyroxene relict grains contained within MMs. |
format |
Article in Journal/Newspaper |
author |
TAYLOR, Susan MATRAJT, Graciela GUAN, Yunbin |
spellingShingle |
TAYLOR, Susan MATRAJT, Graciela GUAN, Yunbin Fine‐grained precursors dominate the micrometeorite flux |
author_facet |
TAYLOR, Susan MATRAJT, Graciela GUAN, Yunbin |
author_sort |
TAYLOR, Susan |
title |
Fine‐grained precursors dominate the micrometeorite flux |
title_short |
Fine‐grained precursors dominate the micrometeorite flux |
title_full |
Fine‐grained precursors dominate the micrometeorite flux |
title_fullStr |
Fine‐grained precursors dominate the micrometeorite flux |
title_full_unstemmed |
Fine‐grained precursors dominate the micrometeorite flux |
title_sort |
fine‐grained precursors dominate the micrometeorite flux |
publisher |
Wiley |
publishDate |
2011 |
url |
http://dx.doi.org/10.1111/j.1945-5100.2011.01292.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1945-5100.2011.01292.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1945-5100.2011.01292.x |
long_lat |
ENVELOPE(101.133,101.133,-66.117,-66.117) |
geographic |
South Pole Jupiter |
geographic_facet |
South Pole Jupiter |
genre |
South pole |
genre_facet |
South pole |
op_source |
Meteoritics & Planetary Science volume 47, issue 4, page 550-564 ISSN 1086-9379 1945-5100 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/j.1945-5100.2011.01292.x |
container_title |
Meteoritics & Planetary Science |
container_volume |
47 |
container_issue |
4 |
container_start_page |
550 |
op_container_end_page |
564 |
_version_ |
1811645436174270464 |