Lesson 1X-ray diffraction (XRD): phase identification goals and sample preparation notesCover XRD for BIF, aiming at phase spotting, measuring iron oxides, carbonates, silicates, and spotting non-crystal bits. Focus on sampling, grinding right, and dodging alignment issues.
Choosing representative XRD samplesPowder preparation and grain-size controlInstrument settings and scan parametersIdentifying iron oxides, carbonates, silicatesSemi-quantitative phase estimation limitsLesson 2Stable isotopes (O, Si, C): what each proxy reveals about temperature, fluid sources, and diagenesisLook at stable O, Si, C isotopes in BIF materials, what each tells about temps, fluid origins, rock-water mixes, and changes, plus mixing multi-isotope data with rock observations.
Sampling carbonates, cherts, and silicatesO isotope constraints on fluid temperatureSi isotopes and silica source signalsC isotopes in associated carbonatesCombining isotopes with petrographyLesson 3Dating approaches relevant to BIF studies: U-Pb on intercalated volcanics or zircons, Re-Os on sulfides, and stratigraphic correlation methodsReview dating for BIF layers like U-Pb on zircon from mixed volcanics, Re-Os on sulphides, and chemical/rock layer matching, noting strengths, doubts, and mixing tips.
Selecting datable interlayered unitsU-Pb zircon sampling and interpretationRe-Os sulfide sampling and limitationsChemostratigraphic correlation in BIFsIntegrating ages with regional stratigraphyLesson 4Designing a sampling plan: sample spacing in outcrop and core, targeting cycles, and strategies for composite sectionsPlan BIF sampling in outcrop/core with spacings, cycle targets, rock shifts, and combined sections that keep layer order while staying practical.
Defining scientific questions and scalesSampling spacing in outcrop and coreTargeting facies and cycle boundariesBuilding composite stratigraphic sectionsDocumenting locations and metadataLesson 5Optical petrography: objectives, thin-section techniques (transmitted and reflected light), and key textures to documentIntro to optical rock study for BIF, using light through and bounce-back thin slices to show minerals, textures, tiny structures from deposition, changes, deformation, fluid overlays.
Objectives of BIF petrographic studiesPreparing transmitted light thin sectionsPreparing reflected light polished sectionsRecognizing primary banding and laminationIdentifying diagenetic and metamorphic texturesLesson 6Iron isotope analyses and their interpretive use for redox and source studiesIntro iron isotope work in BIF, sampling plans, cleaning, mass spec, and how δ56Fe values pin down redox, iron sources, bugs activity, changes in old basins.
Sampling strategies for Fe isotopesChemical purification of iron fractionsMC-ICP-MS measurement considerationsInterpreting δ56Fe in depositional settingsRecognizing diagenetic isotope overprintsLesson 7Types of samples: bulk rock, oriented slabs, thin sections, polished mounts, and targeted micro-drilled powdersDefine BIF sample kinds and uses, from whole rock/slabs to thin slices, polished bits, micro-drills, each aiding rock, chem, isotope work and reads.
Bulk rock samples for whole-rock chemistryOriented slabs for structural contextStandard and doubly polished thin sectionsPolished mounts for reflected light and EMPAMicro-drilled powders for isotope analysesLesson 8Whole-rock major and trace element geochemistry (XRF/ICP-MS): elements to measure, expected ranges, and redox-sensitive proxies (Fe, Si, Mn, P, rare earth elements)Explain whole-rock XRF/ICP-MS for BIF, targets, ranges, redox trackers like Fe, Si, Mn, P, REE shapes for deposition/change conditions.
Sampling and contamination avoidanceFusion and dissolution preparation methodsKey major elements and Fe/Si ratiosTrace elements and REE pattern metricsRedox-sensitive elemental proxy selectionLesson 9Electron microprobe and SEM-EDS: mineral chemistry, zoning, and micro-texture documentationDetail electron probe/SEM-EDS for BIF, mineral chem, zoning, tiny textures. Plan lines, read maps, link tiny views to whole-rock chem.
Sample polishing and coating requirementsBackscattered and secondary electron imagingPoint analyses and line transectsElemental mapping of mineral zoningLinking microtextures to bulk chemistry
