Scientific MUE: acquisition of Laser Ablation Split Stream System (LASS) for isotopic analysis of geological materials by ICPMS

• Grant number: 22/11421-6
• Support Opportunities: Research Infrastructure Program - Scientific
• Start date: August 01, 2023
• End date: July 31, 2030
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Miguel Angelo Stipp Basei
• Grantee: Miguel Angelo Stipp Basei
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated researchers: Luigi Jovane ; Valdecir de Assis Janasi
• Associated scholarship(s): 24/21919-7 - Mass Spectrometry: LA-ICP-MS Split Stream Technique, BP.TT

Abstract

Major advances in Earth Science were provided by the ability to measure isotope abundances and isotope ratios directly on solid materials (usually minerals) with high spatial resolution. Major applications include high precision geochronology (e.g., U-Pb dating of zircon, monazite and many other reliable geochronometers), isotope geochemistry of the most important radiogenic (U-Th-Pb, Lu-Hf, Sm-Nd, Rb-Sr) and non-radiogenic (metals Li, Mg, Ca, Fe, Cu, Zn and Mo and metalloids B, Si, Ge) systems, and elemental trace-element composition down to the parts per billion levels.The laboratories SHRIMP-2e, LA-MC-ICPMS and LA-Q-ICPMS, installed in different Research Centers at the Institute of Geosciences of the University of São Paulo have been offering access to such analyses to all scientific community from Brazil and other countries mainly from South America, for more than a decade, keeping a high standard of quality and elevated productivity. The development of the Laser-Ablation Split Systems (LASS) method allowed the capability for simultaneously gathering the results of age/isotope and elemental composition from a single volume of a mineral. These integrated LASS require that the aerosol produced by the laser is ''split'' into two or more separate "streams" on separate ICPMS instruments to simultaneously measure different chemical and isotopic systems. In essence, the LASS technique requires the combination of an ICPMS capable to measure a large mass range (either a sector field SF-ICPMS or a quadrupole Q-ICPMS) and a MC-ICPMS to measure with the highest precision selected isotope ratios, e.g., Lu-Hf, Sm-Nd, Rb-Sr and Pb-Pb.The acquisition of Neoma MC-ICP-MS and ELEMENT2 XR ICPMS spectrometers by CPGeo will enable the configuration of a LASS, unprecedented in Brazil. This system will allow the IGc-USP not only to maintain the excellence of its laboratories but also to place it on the international scientific frontier, because few laboratories have compatible analytical conditions. The new system has unprecedented advantages over current analytical procedures, especially:1-Separate sessions necessarily imply the analyses of different volumes of the sample, which potentially have compositional contrasts, then invalidating the basic assumption that the two measured parameters are representative of a single volume. Examples of misinterpretations derived from the use of separate sessions, as revealed by later split stream analyses abound in recent literature (e.g., Harrison et al., 2008; Fisher et al., 2014).2-Some of the more useful information on magmatic and metamorphic processes is preserved in tiny (often <100 µm large) accessory minerals (e.g., zircon, monazite, apatite, titanite), which are often compositionally zoned. It is not infrequent that the volume available to yield the required information in these minerals is sufficient for just a single shot, so that only a LASS analysis can extract the desired result (either isotope ratios + trace-element or age + isotope ratios).3-An additional, and significant, advantage is that the total analysis time will be reduced by half, a notable gain in productivity that will make it possible to diversify methods and serve a wide range of internal and external users.The proposed configuration (LASS) allows maximum performance and flexibility in the analysis of minerals and other geological materials. The maximum precision isotopic analyses will be directed to the latest generation MC-ICPMS (Neoma), which has several advantages over the similar equipment of the previous generation (Neptune), with emphasis on the presence of a collision/reaction cell, a unique mass filtering technology that opens fields of great interest, such as in-situ Rb-Sr dating (eliminating the mass interference of Rb on Sr with the formation of SrF) which, due to its wide application, has been bringing new light to several fields of geosciences. (AU)