Mineralogical And Geochemical Characterization At A Micro-Scale Of A New Natural Chalcopyrite Reference Material For In-Situ Fe Isotopic Ratio Analysis

Abstract

Chalcopyrite is a widely distributed Fe sulfide in magmatic and magmatic-hydrothermal systems. Stable Fe isotope analysis of Fe-bearing sulfides has been proven to be a powerful tool for tracking the evolution of these deposits and analyzing their mineralization mechanisms. Previous geological studies using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS), which makes it challenging to determine the Fe isotopic values of small or structurally complex chalcopyrite, have shown that the  56 Fe values of chalcopyrite fall within a wide range (~4‰). In-situ Fe isotope analysis using laser ablation MC-ICP-MS (LA-MC-ICP-MS) and secondary ion mass spectrometry (SIMS), featuring high precision and spatial resolution, can effectively compensate for the above deficiencies. However, the accuracy of in-situ techniques is mainly controlled by matrix-matched reference materials (RMs). To change the present situation in which there is no ideal natural chalcopyrite RMs for Fe isotopic ratio determination, we evaluated the feasibility of natural chalcopyrite (Tianyu-Ccp) collected from the Tianyu magmatic Ni-Cu sulfide deposit (China) as the RM for in-situ Fe isotopic microanalysis. The Tianyu-Ccp chalcopyrite is homogeneous in terms of major elements and Fe isotopic compositions. For in-situ microanalysis, the standard deviation of the Fe isotopic composition is 0.19‰ (2 SD, n = 86) for  56 Fe value. The best recommended Fe isotopic composition, measured by solution MC-ICP-MS, is a  56 Fe value of 0.39 ± 0.07‰ (2 SD, n = 4), based on four different chalcopyrite grains. Therefore, we propose Tianyu-Ccp chalcopyrite as a potential natural RM for in-situ Fe isotopic ratio analysis and expect it to be used for further tracing the formation and evolution of sulfide deposits.

Genesis of the Baiyun Gold Deposit in Northeast Hubei Province, China: Insights from In Situ Trace Elements and S-Fe Isotopes of Sulfide

“…A highly sensitive injection cone combination ('X' skimmer cone + 'Jet' sample cone) was used to achieve a signal intensity for 56 Fe of approximately 10 V in high-resolution mode. To minimize the matrix effect, sulfide standards similar to the sample matrix were used as standard samples (pyrite standard sample Tianyu-Py, pyrrhotite standard sample JC-Po, niobium pyrite standard sample JC-Pn, and chalcopyrite standard sample Tianyu-Ccp), and the standard sample-standard crossover method was used for quality discrimination correction [61][62][63].…”

Accurate Measurement Of Mg Isotopes In Twenty-Four Reference Materials By MC-ICP-MS With A Highly Efficient Optimized Method

“…Mass spectrometry. Mg isotopes were determined using doublefocusing MC-ICP-MS (Neptune Plus, Thermo Fisher Scientific, Bremen, Germany) [23][24][25][26][27][28][29][30][31] at the China University of Geosciences, Wuhan. The sample solutions were nebulized and introduced using a Thermo Finnigan stable introduction system (SIS, ~ 50 μl min -1 PFA nebulizer and quartz glass spray chamber) coupled with an autosampler (ASX-112FR; Cetac Technologies, Omaha, NE, USA).…”