Thermal history of Apollo 12 granite and KREEP-rich rock: Clues from Pb/Pb ages of zircon in lunar breccia 12013
Thermal history of Apollo 12 granite and KREEP-rich rock: Clues from Pb/Pb ages of zircon in lunar breccia 12013
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阿波罗 12 号花岗岩和富含 KREEP 岩石的热史：来自 12013 年月球角砾岩中锆石 Pb/Pb 年龄的线索
DOI：
10.1016/j.gca.2012.07.023
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发表时间：
2012-10
影响因子：
5
通讯作者：
Liu, Yang
中科院分区：
文献类型：
--
作者：
Zhang, Ai-Cheng;Taylor, Lawrence A.;Wang, Ru-Cheng;Li, Qiu-Li;Li, Xian-Hua;Patchen, Allan D.;Liu, Yang
在月球的镁铁质到超镁铁质岩石学中，花岗岩的存在显得异常。然而，从月海中发现了具有确定的花岗岩结构和矿物学的岩石碎片，它们的年龄表明最终起源于高地。阿波罗12号月海角砾岩12013是这些独特的月球岩石之一，含有丰富的花岗岩成分。它由黑色部分和灰色部分组成，黑色部分主要由斜长石和钠长岩碎片组成，少量为花岗岩碎片，灰色部分主要由花岗岩成分组成。结合阴极发光（CL）成像和微米尺度，离子探针测年技术，从这个角砾岩的锆石颗粒进行了研究。黑色部分的锆石年龄变化较大（4.0-4.3Ga）。其中一些在单个颗粒内表现出复杂的年龄分带，对应于CL分带。灰色部分的锆石颗粒没有CL分带特征，但不同颗粒之间的年龄差异较大（4.2-4.3Ga）。本文认为，12013年锆石年龄的大幅度变化、不同颗粒间和单个颗粒内的年龄变化是由结晶后的撞击事件引起的，其中大部分不是原始结晶年龄。4.3 Ga的锆石年龄可能代表了12013年花岗岩成分的最小结晶年龄，类似于阿波罗14号和17号着陆点的月球花岗岩。这一古老的结晶年龄也意味着月球花岗岩的各种稀土配分模式可能不完全与其结晶年龄有关。通过与阿波罗12号、14号和17号着陆点锆石207 Pb/206 Pb年龄的对比，我们认为在3.9Ga之前至少有一次月球大撞击事件，发生在距今4.2Ga。
With the mafic to ultramafic petrology of the Moon, the presence of granite appears anomalous. However, fragments of rocks with a definite granitic textures and mineralogy have been recovered from the maria, where their ages point to an ultimate origin in the highlands. Apollo 12 mare breccia 12013 is one of these unique lunar rocks, containing abundant granitic components. It consists of a black portion, composed mainly of fragments of plagioclase and noritic rock, with minor fragments of granitic rock, and a gray portion that is dominated by an overall granitic component. Zircon grains from this breccia were studied by combining cathodoluminescence (CL) imaging and micron-scale, ion-microprobe dating techniques. Zircon grains from the black portion have a large age variation (4.0–4.3Ga). A few of them exhibit complex age zoning within individual grains, corresponding to CL zoning. Zircon grains from the gray portion show no CL zoning features but also have a large age variation between different grains (4.2–4.3Ga). In this study, we suggest that the large age variations of zircon in 12013, among different grains and within individual grains were caused by post-crystallization impact events, and most of them are not original crystallization ages. The 4.3-Ga zircon age probably represents the minimum crystallization age of the granitic component in 12013, similar to lunar granites from the Apollo 14 and 17 landing sites. This old crystallization age also implies that various REE patterns of lunar granites might not be entirely related to their crystallization ages. Based on comparison with the207Pb/206Pb ages for zircon from the Apollo 12, 14, and 17 landing sites, we suggest that there was at least one pre-3.9Ga major impact event on the Moon, at ∼4.2Ga.
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DOI：
--
发表时间：
2000
期刊：
--
影响因子：
--
作者：
G. Snyder;L. Borg;L. Nyquist;L. Taylor
通讯作者：
G. Snyder;L. Borg;L. Nyquist;L. Taylor
影响因子：
5.3
作者：
G. Turner
通讯作者：
G. Turner
影响因子：
2.2
作者：
C. Meyer;I. Williams;W. Compston
通讯作者：
C. Meyer;I. Williams;W. Compston
影响因子：
2.2
作者：
A. Nemchin;R. Pidgeon;D. Healy;M. Grange;M. Whitehouse;J. Vaughan
通讯作者：
A. Nemchin;R. Pidgeon;D. Healy;M. Grange;M. Whitehouse;J. Vaughan
影响因子：
5.3
作者：
J. Laul;R. Keays;R. Ganapathy;E. Anders
通讯作者：
J. Laul;R. Keays;R. Ganapathy;E. Anders