Unique angrite-like fragments in a CH3 chondrite reveal a new basaltic planetesimal
Unique angrite-like fragments in a CH3 chondrite reveal a new basaltic planetesimal
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CH3 球粒陨石中独特的类红陨石碎片揭示了一种新的玄武岩星子
DOI：
10.1016/j.gca.2020.02.014
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发表时间：
2019-07
影响因子：
5
通讯作者：
Yurimoto Hisayoshi
中科院分区：
文献类型：
--
作者：
Zhang Ai-Cheng;Kawasaki Noriyuki;Kuroda Minami;Li Yang;Wang Hua-Pei;Bai Xue-Ning;Sakamoto Naoya;Yin Qing-Zhu;Yurimoto Hisayoshi
大多数陨石被认为是星子的碎片，可以为限制早期太阳系的化学演化和动态历史提供线索。在这项研究中，我们报道了两个独特的碎片（ALF-1和ALF-2）包裹在CH3碳质球粒陨石Sayh al Uhaymir 290中。这两个碎片以富钙、富铁橄榄石为主，含不同数量的Al、富钛奥辉石、钙长石、氧化矿物、钙磷矿物、FeNi金属、顽辉石和少量富铝、富钛奥辉石。两块岩石中橄榄石颗粒的Ca-Mg-Fe分系统和Fe/Mn比值与火山辉长岩相似。这些相似的特征表明，这两个碎片的母体可能具有类似于辉石母体的大块化学、氧逸度和分化。然而，高精度SIMS测量结果显示，两块陨石中橄榄石的氧同位素组成Δ17O = 0.91 ± 0.18‰（2σ）与已知的angrite陨石明显不同，可能是一种新型的玄武岩类星子。这两个碎片也有一些矿物学特征不同于花岗岩陨石。它们包括：(1)缺乏典型的火成岩结构；(2)两种空间关联的富Al、富ti、不同CaO、Al2O3、MgO和P2O5含量的铝质共存；(3) ALF-1中存在顽辉石显性边缘；(4) ALF-1中存在富Cr、富mn边缘；(5)氧化矿物中复杂的微观非均质性。我们认为这些特征可能是由于它们的母体和/或从母体弹射出来后的复杂热历史造成的。在这些特征中，ALF-1富含锰、铬的边缘和以辉化辉石为主的边缘可以用星云环境中的热事件来最好地解释。这意味着这两个碎片的母体分化可能发生在星云气体消散之前。
Most meteorites are believed to be chips from planetesimals and can provide clues to constrain the chemical evolution and dynamic history of the early Solar System. In this study, we report two unique fragments (ALF-1 and ALF-2) enclosed in the CH3 carbonaceous chondrite Sayh al Uhaymir 290. These two fragments are dominated by Ca,Fe-rich olivine with various amounts of Al,Ti-rich augite, anorthite, oxide minerals, Ca-phosphate mineral, FeNi metal, enstatite, and less Al,Ti-rich augite. The Ca-Mg-Fe systematics and Fe/Mn ratios of olivine grains in the two fragments are similar to that of the volcanic angrites. These similar features imply that the parent body of the two fragments might have bulk chemistry, oxygen fugacity, and differentiation resembling the angrite parent body. However, high-precision SIMS measurements reveal oxygen isotope compositions Δ17O = 0.91 ± 0.18‰ (2σ) of olivine in the two fragments are distinctly different from that of known angrite meteorites, possibly representing a new type of basaltic planetesimal.The two fragments also have a few mineralogical features distinct from angrite meteorites. They include: (1) the lack of a typical igneous texture; (2) the coexistence of two spatially associated Al,Ti-rich augites with different contents of CaO, Al2O3, MgO, and P2O5; (3) the presence of an enstatite-dominant rim in ALF-1; (4) the presence of a Cr,Mn-rich margin in ALF-1; and (5) complex microscale heterogeneity in oxide minerals. We argue that these features could be due to complex thermal histories in their parent body and/or after ejection from their parent body. Among these features, the Mn,Cr-rich margin and the enstatite-dominant rim in ALF-1 can be best explained with thermal events in nebular settings. This implies that the differentiation of the parent body of the two fragments might have taken place prior to the dissipation of the nebular gas.
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影响因子：
2.2
作者：
D. Nakashima;T. Ushikubo;Rudraswami N. Gowda;N. Kita;J. Valley;K. Nagao
通讯作者：
D. Nakashima;T. Ushikubo;Rudraswami N. Gowda;N. Kita;J. Valley;K. Nagao
影响因子：
5
作者：
A. Zhang;S. Itoh;N. Sakamoto;Rucheng Wang;H. Yurimoto
通讯作者：
A. Zhang;S. Itoh;N. Sakamoto;Rucheng Wang;H. Yurimoto
DOI：
10.1086/510360
发表时间：
2007-02
期刊：
The Astrophysical Journal
影响因子：
--
作者：
A. Trinquier;J. Birck;C. Allègre
通讯作者：
A. Trinquier;J. Birck;C. Allègre
DOI：
--
发表时间：
2018-03
期刊：
--
影响因子：
--
作者：
G. Budde;C. Burkhardt;T. Kleine
通讯作者：
G. Budde;C. Burkhardt;T. Kleine
DOI：
--
发表时间：
2010-03
期刊：
--
影响因子：
--
作者：
M. Sanborn;M. Wadhwa
通讯作者：
M. Sanborn;M. Wadhwa