Acquisition and Development of an Ultra Violet Laser Sulfur Isotope Microprobe for the Analysis 32S, 33S, 34S, and 36S in Sulfide Minerals

0215953 Rumble获得一种新的同位素比率监测、气相色谱进样质谱仪(IRMS-GC MS)，配备四个收集器和四个通道输出，用于同时分析SF6离子束，这将使开发一种新的紫外光(UV)激光氟化微探针成为可能，用于分析硫化物矿物中的32S、33S、34S和36S。根据以前成功的硅酸盐矿物氧同位素原位微量分析的经验，应该可以测量硫化物矿物上50微米直径的斑点，其精度在d33S和d34S中为0.1-0.2/mil，在？33s中为0.05/mil。由于同位素36S的稀有性，对d36S的分析将处于较低的精度水平。一种新的紫外光激光宏探针和GC净化系统已经建成，并已用于400微米直径的硫同位素光斑测量，使用现有的质谱仪不能进行GC连续流动操作。NSF-MRI需要新的IRMS-GC MS来提高分析空间分辨率，从400微米提高到50微米。新的硫同位素微探针将被用来检验通过硫化物矿物直接氟化在太古宙岩石中发现与质量无关的硫同位素异常的有效性。这些异常与地球大气氧化之间的关系将通过对太古宙-元古界过渡时期钻探岩心的详细测量来检验。将通过矿物间分馏和矿物内同位素不均一性的空间分辨分析来研究岩石中固定质量无关特征的机制。新的微探针分析微克样品的能力将用于微生物对硫同位素进行分馏的实验室研究。新的硫同位素微探头的使用将向整个研究界的合格用户开放。

0215953RumbleThe acquisition of a new isotope-ratio-monitoring, gas chromatograph inlet mass spectrometer (IRMS-GC MS) equipped with four collectors and four channel output for simultaneous analysis of the ion beams of SF6 will make it possible to develop a new ultraviolet (UV) laser fluorination microprobe for the analysis of 32S, 33S, 34S, and 36S in sulfide minerals. Based on previous experience with the successful in situ microanalysis of oxygen isotopes in silicate minerals, it should be possible to measure 50-micrometer diameter spots on sulfide minerals with a precision of 0.1 to 0.2 per mil in d33S and d34S and 0.05 per mil in ?33S. Analysis for d36S will be at a lower level of precision owing to the rarity of the isotope 36S. A new UV laser macroprobe and GC purification system has already been built and validated for 400 micrometer diameter spot measurements of sulfur isotopes using an existing mass spectrometer that is incapable of GC-continuous flow operation. The new IRMS-GC MS requested from NSF-MRI is needed to improve analytical spatial resolution from 400 to 50 micrometers. The new sulfur isotope microprobe will be used to test the validity of the discovery of mass-independent sulfur isotope anomalies in Archean rocks by direct fluorination of sulfide minerals. The proposed relationship between the anomalies and the oxygenation of Earth's atmosphere will be tested by detailed measurements of drill cores spanning the Archean-Proterozoic transition. The mechanisms responsible for fixing mass-independent signatures in rocks will be investigated through spatially resolved analyses of inter-mineral fractionations and intra-mineral isotopic heterogeneity. The new microprobe's capacity to analyze microgram samples will be put to use in a laboratory study of the fractionation of sulfur isotopes by microbes. Use of the new sulfur isotope microprobe will be open to qualified users from throughout the research community.