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NanoSIMS Analysis of Siderophile Elements in Metallic Phases of Chondrites
| Content Provider | Semantic Scholar |
|---|---|
| Author | Qin, Lingcan Zhang, Jingchao Hao, Jianhuan Lin, Yange |
| Copyright Year | 2019 |
| Abstract | Introduction: The siderophile (iron-loving) elements, comprising the highly siderophile elements (HSE; including platinum group elements, Re and Au) and the moderately siderophile elements (MSE; including Co, Ni, Ge, Mo, Ag and W), tend to be enriched in metallic phases in the melt due to their high low-pressure metal-silicate partition coefficients (ca. 10 for HSE and 10-10 for MSE)[1]. In addition, the siderophile elements cover a wide range of elemental condensation temperatures, from the most refractory substances (such as Re, Os, Ru and Ir) to the more volatile elements (such as Au and Ge) in the solar nebula[2], which make them as ideal tracers for the process of nebula condensation. The chondrite is a relatively primitive rock and the metal particles are the important constituents of the chondrite, thus metallic phases in chondrites may record information about the origin and evolution of chondritic metals. For example, the composition pattern of the platinum group elements (PGE; including Ru, Rh, Pd, Os, Ir and Pt) in the metallic phases can reflect the process of metal grains’ growth in solar nebula condensation under high temperature conditions[3]. The distribution of siderophile elements between kamacite and taenite in different rock types of chondrites can reveal the thermal history of an asteroid[4]. Traditionally, the analysis of siderophile elements in extraterrestrial materials mainly relies on instrumental neutron activation analysis (INAA) or radiochemical neutron activation analysis (RNAA). Owing to radioactive radiation and the fact that INAA only has a high sensitivity for the measurement of Ir, it is not appropriate for the analysis of other elements. Inductively coupled plasma spectroscopy (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS) are also used to determine those elements in the metallic phase. However, they are only used for bulk analysis, and the loss of samples is huge. The application of laser ablation inductively coupled plasma mass spectrometry (LAICP-MS) and secondary ion mass spectroscopy (SIMS) have made it possible to in suit analysis with high sensitivity in micron-scale(normally >30 micron), whereas a portion of metallic phases in the chondrites we study are smaller than this detection range(Fig.3b). Besides, LA-ICP-MS still consumes samples to some extent and SIMS measurement does not cover all siderophile elements[5]. Extraterrestrial samples are rare and valuable, and some of the metal grains in the samples are extremely tiny (within a size of 10 × 10 μm, Fig3.b). So it is necessary to develop a new method to limit the damage and with high lateral resolution and capability to get the most comprehensive information about the samples. Nanoscale secondary ion mass spectrometry (NanoSIMS), characterized by high spatial resolution (down to 50 nm)[6], is used to analyze HSEs, Ni and Ge of metal standard targets(Fig1), two iron meteorites Hoba and North Chile(Filomena)and metallic phases of a L3 chondrite named Xinglongquan in this paper, in order to study the formation mechanism of metal grains in the solar nebula. |
| Starting Page | 2696 |
| Ending Page | 2696 |
| Page Count | 1 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://www.hou.usra.edu/meetings/lpsc2019/pdf/2696.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
