The Loongana (CL) group of carbonaceous chondrites
The Loongana (CL) group of carbonaceous chondrites
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Loongana (CL) 碳质球粒陨石群
DOI：
10.1016/j.gca.2021.04.007
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发表时间：
2021
影响因子：
5
通讯作者：
Kleine T.
中科院分区：
文献类型：
--
作者：
Metzler K;Hezel D. C;Barosch J;Wölfer E;Schneider J. M;Berndt J;Stracke A;Gattacceca J;Greenwood R. C;Franchi;Burkhardt C.;Kleine T.
对Coolidge、Loongana001、Los Vientos(LOV)051、西北非洲(NWA033)和NWA033这五个未分组的碳质球粒陨石的岩石学、矿物化学、整体化学和同位素组成的协调研究表明，这些陨石具有一套类似的性质，使它们有别于其他碳质球粒陨石群，并允许定义新的Longana(CL)碳质球粒陨石群。所研究样品的基本特征是：(1)亲石元素比(如Al/Mg、Si/Mg)在其他碳质球粒陨石群的典型范围内。(2)Fe-Ni金属丰度明显高于球粒陨石，但与球粒陨石相近。(3)球粒陨石的粒度-频率分布与球粒陨石相似，但与球粒陨石不同。(4)CaI丰度平均值为∼1.4vol%，低于球粒陨石，但远高于球粒陨石。(5)基质含量极低(17-21vol%)，在主要碳质球粒陨石群(CI、CM、CO、CV、CR、CK)中最低。(6)橄榄石处于近平衡状态，其平均Fa值在12.5mol%(Loongana001)和14.7mol%(NWA 13400)之间。(7)与基质相比，CV、CK和CR球粒陨石中Al_2O_3含量较低，而MgO和Cr2O_3含量较高。(8)与其他主要碳质球粒陨石相比，挥发性元素(Mn、Na、K、Rb、Cs、Zn、Se、Te、Pb、Tl)明显亏损，反映出基质丰度较低。(9)整体氧同位素组成沿Ccam线(Δ17O-3.96~-5.47‰)分布，与CV球粒陨石场和CK球粒陨石场部分重叠，但也包括富16O以上的样品。(10)є~(54)Cr-є~(50)Ti同位素图上CL值位置独特，є~(54)Cr值与CV、CK、CO相近，而є~(50)Ti值与CR球粒陨石相似。所研究的CL球粒陨石的岩石学类型为3.9~4型，表明它们在母体上经历了热变质作用。文中详述的CL球粒陨石的诊断特征为识别较低岩石学类型的CL成员提供了依据。这些样品对于确定这些陨石及其成分的原始状态将是重要的。
A coordinated study of the petrology, mineral chemistry, and bulk chemical and isotopic composition of the five ungrouped carbonaceous chondrites Coolidge, Loongana 001, Los Vientos (LoV) 051, Northwest Africa (NWA) 033, and NWA 13400 reveals that these meteorites have a similar set of properties that distinguishes them from the other carbonaceous chondrite groups and allows definition of the new Loongana (CL) group of carbonaceous chondrites. The basic characteristics of the investigated samples are: (1) Lithophile element ratios (e.g., Al/Mg, Si/Mg) are within the typical range of other carbonaceous chondrite groups. (2) Fe-Ni metal abundances are considerably higher than for CV, but similar to CR chondrites. (3) Chondrule size-frequency distributions are similar to CV, but dissimilar to CR chondrites. (4) The mean CAI abundance is ∼1.4 vol%, i.e., lower than in CV but much higher than in CR chondrites. (5) Very low amounts of matrix (17-21 vol%), the lowest among the main carbonaceous chondrite groups (CI, CM, CO, CV, CR, CK). (6) Olivine is nearly equilibrated, with mean fayalite (Fa) values between 12.5 mol% (Loongana 001) and 14.7 mol% (NWA 13400) as a metamorphic effect. (7) Lower Al2O3and higher MgO and Cr2O3concentrations in matrix, compared to matrix in CV, CK, and CR chondrites. (8) Volatile elements (Mn, Na, K, Rb, Cs, Zn, Se, Te, Pb, Tl) are considerably depleted compared to all other main carbonaceous chondrite groups, reflecting the low matrix abundance. (9) Bulk O isotope compositions plot along the CCAM line (Δ17O -3.96 to -5.47‰), partly overlapping with the CV and CK chondrite field but including samples that are more16O-rich. (10) Unique positions of CL values in the є54Cr-є50Ti isotope plot, with є54Cr values similar to CV, CK, and CO, but є50Ti values similar to CR chondrites. All CL chondrites studied here are of petrologic type 3.9 to 4, indicating that they have been thermally metamorphosed on the parent body. The diagnostic features of CL chondrites detailed here provide a basis for identifying CL members of lower petrologic types. Such samples will be important for determining the pristine state of these meteorites and their components.
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影响因子：
13.6
作者：
M. Weisberg;T. Mccoy;A. Krot
通讯作者：
M. Weisberg;T. Mccoy;A. Krot
影响因子：
5
作者：
H. Knab
通讯作者：
H. Knab
从两个元素图生成相图的数学代码
DOI：
10.1016/j.cageo.2010.02.002
发表时间：
2010
期刊：
Comput. Geosci.
影响因子：
--
作者：
D. Hezel
通讯作者：
D. Hezel
3 型和 4 型碳质球粒陨石的矿物学、岩石学和分类
影响因子：
2.4
作者：
W. R. Schmus
通讯作者：
W. R. Schmus
4-6 型碳质球粒陨石的岩石学
影响因子：
--
作者：
E. Scott;Jeffrey Taylor
通讯作者：
Jeffrey Taylor