A protocol is presented to perform Broad Ion Beam Polishing (BIBP) of rock thin sections to obtain a surface that can yield high quality crystallographic preferred orientation data using SEM-EBSD. The modus operandi, referred to as Mamtani’s Fabric Analysis Lab (MFAL) protocol, involves flat milling of a rotating rock thin section using a triple ion beam milling system (Leica EM TIC 3X) in which tilt angle of sample (degree) with reference to ion beam (Argon), acceleration voltage (kV) and source current (mA) can be controlled along with lateral and rotary movements. The protocol has been developed after >90 hours of BIBP experiments on various rock samples under different experimental settings (tilt angle/kV/mA) followed by SEM-EBSD analysis. Each experiment was performed at medium rotation speed (7 rpm) with a lateral movement of upto ±7 mm on rectangular rock thin sections (long dimension <25 mm). The best surface for SEM-EBSD analysis of rock thin sections is obtained in two steps of BIBP. In step-1, cleaning of thin section is done for 5 minutes (1.5°/4 kV/1.5 mA). In step-2, polishing is done for 30 minutes (1.5°/4 kV/3 mA). BIBP following MFAL protocol yields very good SEM-EBSD data from hard and soft mineral phases in rocks that enable (a) determination of mineral slip systems, (b) kinematics and (c) EBSD data-based mapping of grain boundaries of soft mineral phases (like hornblende) for petrofabric analysis in a polymineralic rock, which has always remained a challenge from mechanically polished samples. It is concluded that the MFAL protocol saves more than 5 hours of sample preparation time over other sample preparation methods for SEM-EBSD studies.

中文翻译：

---

宽离子束抛光岩石薄片的 SEM-EBSD 分析 — MFAL 协议

提出了一种对岩石薄片进行宽离子束抛光 (BIBP) 的协议, 以获得可以使用 SEM-EBSD 产生高质量晶体学优选取向数据的表面。该方法被称为 Mamtani 的织物分析实验室 (MFAL) 协议，涉及使用三重离子束铣削系统 (Leica EM TIC 3X) 对旋转岩石薄片进行平面铣削，其中样品的倾斜角（度）参考离子束 (Argon)、加速电压 (kV) 和源电流 (mA) 可以随着横向和旋转运动进行控制。该协议是在不同实验设置（倾斜角/kV/mA）下对各种岩石样品进行 >90 小时的 BIBP 实验后制定的，然后是 SEM-EBSD 分析。每个实验都在中等转速 (7 rpm) 下进行，在矩形岩石薄片（长尺寸 <25 mm）上横向移动高达 ±7 mm。通过 BIBP 的两个步骤获得岩石薄片 SEM-EBSD 分析的最佳表面。在第 1 步中，薄切片的清洁时间为 5 分钟（1.5°/4 kV/1.5 mA）。在步骤 2 中，抛光完成 30 分钟（1.5°/4 kV/3 mA）。BIBP 遵循 MFAL 协议从岩石中的硬和软矿物相中产生非常好的 SEM-EBSD 数据，能够 (a) 确定矿物滑移系统，(b) 运动学和 (c) 基于 EBSD 数据的软矿物相晶界映射（如角闪石）用于多矿物岩石中的石油织物分析，这一直是机械抛光样品的挑战。