Dome C ultracarbonaceous Antarctic micrometeorites Infrared and Raman fingerprints
Dome C ultracarbonaceous Antarctic micrometeorites Infrared and Raman fingerprints
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DOI：
10.1051/0004-6361/201731322
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发表时间：
2018-01-08
影响因子：
6.5
通讯作者：
Borondics, F.
中科院分区：
文献类型：
--
作者：
Dartois, E.;Engrand, C.;Borondics, F.
上下文超碳质南极微陨石（UCAMETERIALS）是到达地球表面的行星际尘埃颗粒的一小部分，含有大量其他地方没有的有机成分。他们很可能是从太阳系外部区域对当地行星际尘埃粒子（IDP）通量的贡献中取样。我们的特点UCAturbine组合物集中在有机物，并比较结果的不溶性有机物（IOM）从原始陨石，IDPs，和地球。我们获得了Concordia/CSNSM收集的8种UCAs的同步辐射红外显微光谱（mu FTIR）和mu拉曼光谱，以及用电子探针测定的N/C原子比。光谱主要由具有低脂肪族CH与芳香族C = C比率的有机组分，以及与碳质碳酸盐和IDP相比更高的氮馏分和更低的氧馏分。UCA的羰基吸收带与酮或醛官能团一致。一些IR和拉曼光谱显示出对应于腈的C N带。从1400到1100 cm（-1）的吸收带轮廓与碳质网络中C-N键的存在相一致，并且与陨石IOM中报道的光谱不同。我们确认，硅酸盐碳含量的UCAlidae是远远低于国内流离失所者和陨石报告。再加上相对于构成有机物质基质的碳而言，氮的丰度较高，因此最有可能的情况是，在寒冷的富氮环境中（如太阳系外的冰冷母体表面），通过物理化学机制形成UCAlidae。UCAMM的组成进一步暗示了太阳系原行星盘演化中C/Si和N/C丰度比存在日心正梯度。
Context. Ultra Carbonaceous Antarctic Micro Meteorites (UCAMMs) represent a small fraction of interplanetary dust particles reaching the Earth's surface and contain large amounts of an organic component not found elsewhere. They are most probably sampling a contribution from the outer regions of the solar system to the local interplanetary dust particle (IDP) flux.Aims. We characterize UCAMMs composition focusing on the organic matter, and compare the results to the insoluble organic matter (IOM) from primitive meteorites, IDPs, and the Earth.Methods. We acquired synchrotron infrared microspectroscopy (mu FTIR) and mu Raman spectra of eight UCAMMs from the Concordia/CSNSM collection, as well as N/C atomic ratios determined with an electron microprobe.Results. The spectra are dominated by an organic component with a low aliphatic CH versus aromatic C = C ratio, and a higher nitrogen fraction and lower oxygen fraction compared to carbonaceous chondrites and IDPs. The UCAMMs carbonyl absorption band is in agreement with a ketone or aldehyde functional group. Some of the IR and Raman spectra show a C N band corresponding to a nitrile. The absorption band profile from 1400 to 1100 cm(-1) is compatible with the presence of C-N bondings in the carbonaceous network, and is spectrally different from that reported in meteorite IOM. We confirm that the silicate-to-carbon content in UCAMMs is well below that reported in IDPs and meteorites. Together with the high nitrogen abundance relative to carbon building the organic matter matrix, the most likely scenario for the formation of UCAMMs occurs via physicochemical mechanisms taking place in a cold nitrogen rich environment, like the surface of icy parent bodies in the outer solar system. The composition of UCAMMs provides an additional hint of the presence of a heliocentric positive gradient in the C/Si and N/C abundance ratios in the solar system protoplanetary disc evolution.