Rosa2.ppt Geochemical analysis and rock sampling
- 1. Teaching Geochemistry Workshop Teaching Geochemistry Workshop Rock Samples and Rock Samples and Geochemical Analysis Geochemical Analysis Maria de Lourdes Rosa & Débora Correia Rios Maria de Lourdes Rosa & Débora Correia Rios Federal University of Bahia Federal University of Bahia Earth Sciences Institute Earth Sciences Institute Brazil Brazil Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA
- 2. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Geochemistry at the Geochemistry at the Federal University of Bahia - Brazil Federal University of Bahia - Brazil
- 3. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Geochemistry at the Geochemistry at the Federal University of Bahia (UFBA) - Brazil Federal University of Bahia (UFBA) - Brazil Brief Description Brief Description • 2 Disciplines of Geochemistry 2 Disciplines of Geochemistry Chemistry for Geologists (first year) Chemistry for Geologists (first year) Geochemistry (fourth year) Geochemistry (fourth year) For who? For who? • Undergraduate students of Geology Undergraduate students of Geology Background: Background: • Introductory Geology Introductory Geology
- 4. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Chemistry for Geologists Course Chemistry for Geologists Course Syllabus - Lectures (60%) Syllabus - Lectures (60%) Lab Activities (40%) Lab Activities (40%) 48 students/semester 48 students/semester 2 Teachers 2 Teachers 75 hours/semester 75 hours/semester • 30 h Lectures 30 h Lectures • 45 h Laboratory Activities 45 h Laboratory Activities
- 5. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Laboratory Activities Laboratory Activities 15 Laboratory Activities: 1 per week 15 Laboratory Activities: 1 per week The laboratory practices are for students to The laboratory practices are for students to recognize what is involved in modern recognize what is involved in modern geochemistry analyses of these geological geochemistry analyses of these geological materials: materials: Rocks and minerals Rocks and minerals Water Water Soil and sediments Soil and sediments
- 6. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Goals for Lab Activities Goals for Lab Activities Types of materials subject to geochemical analysis. Types of materials subject to geochemical analysis. Procedures and care in sampling. Procedures and care in sampling. Tools for sample preparation. Tools for sample preparation. Avoiding contamination and common errors. Avoiding contamination and common errors. Analytical Instruments at UFBA: Analytical Instruments at UFBA: • ICP-AES ICP-AES • AAS AAS • XRF XRF • Microprobe Microprobe
- 7. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Rock Sample Preparation: AC-01 Rock Sample Preparation: AC-01 Lab Activity 01: What do geochemical analysis mean? Lab Activity 01: What do geochemical analysis mean? • Research about geochemical analysis Research about geochemical analysis. . Websites Websites Earth Sciences Institute Library Earth Sciences Institute Library • At this point, we will discuss different kind geologic samples At this point, we will discuss different kind geologic samples and ways of reporting geochemistry data. and ways of reporting geochemistry data. Tables Tables Qualitative versus quantitative analyses Qualitative versus quantitative analyses Major, minor and trace constituents Major, minor and trace constituents Chemical form Chemical form
- 8. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Rock Sample Preparation: AC-01 Rock Sample Preparation: AC-01 Lab Activity 01: What do geochemical analysis Lab Activity 01: What do geochemical analysis mean? mean? • Students will discuss the analyses as Students will discuss the analyses as measurements which provide quantitative measurements which provide quantitative information about the chemical composition of a information about the chemical composition of a sample and the importance of the results. sample and the importance of the results.
- 9. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Rock Sample Preparation: AC-02 Rock Sample Preparation: AC-02 Lab Activity 02: Sampling Lab Activity 02: Sampling • Sample Collection Sample Collection Sample scheme: What to collect? Sample scheme: What to collect? Geochemical investigation: How to proceed? Geochemical investigation: How to proceed? How many and how much: number and size of samples How many and how much: number and size of samples that I need that I need Which tools should be used? Which tools should be used? Identification: Sample protocols Identification: Sample protocols • Field Activity Field Activity Neighborhood Neighborhood Granite outcrops Granite outcrops
- 10. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Rock Sample Preparation: AC-02 Rock Sample Preparation: AC-02 Lab Activity 02: Sampling Lab Activity 02: Sampling • Students must understand the importance of Students must understand the importance of sampling and of a well planned field study and sampling and of a well planned field study and the importance of these steps in the the importance of these steps in the geochemical analysis. geochemical analysis.
- 11. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Rock Sample Preparation: AC-03 Rock Sample Preparation: AC-03 Lab Activity 03: Classic Sample Preparation Lab Activity 03: Classic Sample Preparation • Granulometric Reduction Granulometric Reduction • Polished slice Polished slice • Rock powder Rock powder • Mineral Concentration Mineral Concentration • Effects of these choices on the results Effects of these choices on the results
- 12. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Sample Preparation Laboratory Sample Preparation Laboratory • 1 Hydraulic rock breaker 1 Hydraulic rock breaker • 3 Stell crushers 3 Stell crushers • And also other tools… And also other tools… Hammers Hammers Sieves Sieves Paper Paper Storage containers… Storage containers… Rock Sample Rock Sample Preparation: AC-03 Preparation: AC-03
- 13. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Rock Sample Preparation: AC-03 Rock Sample Preparation: AC-03 Reciprocating rock crusher Sample Preparation Laboratory Sample Preparation Laboratory • During these steps, students During these steps, students will: will: Perform a typical procedure Perform a typical procedure for preparing solid rock for preparing solid rock samples for analyses. samples for analyses. Discuss the media used to Discuss the media used to fabricate the equipments and fabricate the equipments and risks of sample contamination. risks of sample contamination.
- 14. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Rock Sample Preparation: AC-03 Rock Sample Preparation: AC-03 Sample Preparation Laboratory Sample Preparation Laboratory • During these steps, students will see: During these steps, students will see: Representative fractions of sample to analyze Representative fractions of sample to analyze Sample storage Sample storage Possible sources of systematic errors Possible sources of systematic errors
- 15. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Shatter Box Mineral Concentration Laboratory Mineral Concentration Laboratory • 2 Swing mills 2 Swing mills Tungsten carbide pot Tungsten carbide pot Agate pot Agate pot • 1 Ball mill 1 Ball mill Hardened steel balls Hardened steel balls • 1 Mineral Separator Table 1 Mineral Separator Table • 2 Frantz 2 Frantz Isodynamic magnetic separator Isodynamic magnetic separator • Heavy Liquids Heavy Liquids Bromophorm Bromophorm Rock Sample Preparation: AC-03 Rock Sample Preparation: AC-03
- 16. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Rock Sample Preparation: AC-03 Rock Sample Preparation: AC-03 Mineral Concentration Laboratory Mineral Concentration Laboratory • Other skills and goals for this activity are to concentrate mineral Other skills and goals for this activity are to concentrate mineral grains. Students will be taught that some geochemical procedures grains. Students will be taught that some geochemical procedures require a pure mineral sample and that a single mineral can be require a pure mineral sample and that a single mineral can be physically separated from the rock. physically separated from the rock.
- 17. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Rock Sample Preparation: AC-03 Rock Sample Preparation: AC-03 Lab Activity 03: Classic Sample Preparation Lab Activity 03: Classic Sample Preparation • At the end of this step, students will At the end of this step, students will be able to prepare their samples: be able to prepare their samples: Thin sections Thin sections Powder Powder Mineral concentration Mineral concentration • Now, they have samples ready for Now, they have samples ready for XRF (powder - solid disc) and XRF (powder - solid disc) and Electron Microprobe analysis (thin Electron Microprobe analysis (thin section). section).
- 18. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Rock Sample Preparation: AC-04 Rock Sample Preparation: AC-04 Lab Activity 04: Sample decomposition-solution Lab Activity 04: Sample decomposition-solution • The Lab environment The Lab environment Safety in the geochemistry lab Safety in the geochemistry lab Equipments Equipments Glasses Glasses Reagent purity and blanks Reagent purity and blanks • Here, following the physical preparation procedures, Here, following the physical preparation procedures, students will perform one or more stages of chemical students will perform one or more stages of chemical processing. processing.
- 19. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Rock Sample Preparation: AC-04 Rock Sample Preparation: AC-04 Lab Activity 04: Sample decomposition-solution Lab Activity 04: Sample decomposition-solution Acid digestion (open and closed systems) Acid digestion (open and closed systems) Alkaline fusions Alkaline fusions
- 20. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Rock Sample Preparation: AC-04 Rock Sample Preparation: AC-04 Lab Activity 04: Sample Decomposition-Solution Lab Activity 04: Sample Decomposition-Solution • By the end of this activity, rock samples were By the end of this activity, rock samples were converted into solution by a variety of procedures. converted into solution by a variety of procedures. • Therefore, we will emphasize the procedures Therefore, we will emphasize the procedures producing solutions suitable for analysis by ICP-AES producing solutions suitable for analysis by ICP-AES and AAS. and AAS.
- 21. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Geochemical Analyses: AC-05 Geochemical Analyses: AC-05 Lab Activity 05: Running Samples Lab Activity 05: Running Samples • ICP-AES – AAS – XFR – Microprobe ICP-AES – AAS – XFR – Microprobe ICP-AES AAS
- 22. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Geochemical Analyses: AC-05 Geochemical Analyses: AC-05 Lab Activity 05: Running Samples Lab Activity 05: Running Samples • From the analytical viewpoint, students will perform From the analytical viewpoint, students will perform the analyses using the instrumental methods the analyses using the instrumental methods available at the Federal University of Bahia. available at the Federal University of Bahia. • Additionally they will be able to evaluate the Additionally they will be able to evaluate the differences in methods and results by comparison differences in methods and results by comparison Time to get an analysis Time to get an analysis Precision and accuracy Precision and accuracy Costs Costs
- 23. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Student Evaluation Student Evaluation Students work in groups of four (3 groups Students work in groups of four (3 groups per class) per class) • For each activity a preliminary report For each activity a preliminary report • A seminar b A seminar by the end of the term including: y the end of the term including: A final write-up: first time they are expected to write A final write-up: first time they are expected to write up their own data up their own data An oral presentation An oral presentation Seminars allow comparison between the groups. Seminars allow comparison between the groups. Each one uses a distinct analytical method. Each one uses a distinct analytical method.
- 24. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Difficulties Difficulties Restricted funds Restricted funds Time for assessment this discipline is Time for assessment this discipline is insufficient insufficient Absence of Technical Support Absence of Technical Support • Labs off-routine Labs off-routine Students missing classes Students missing classes References: References: • Scarcity Scarcity • Native language: English Native language: English
- 25. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Solutions Solutions Limit field activities to nearby the University Limit field activities to nearby the University Buy some books ourselves Buy some books ourselves Limiting the course reference to the ones available Limiting the course reference to the ones available Resuming and translating some texts and making Resuming and translating some texts and making them available to students them available to students Emphasizing operating methods Emphasizing operating methods Looking for working labs in other institutes Looking for working labs in other institutes
- 26. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Nice News… Nice News… The GeoChronos Net: The GeoChronos Net: • A Brazilian national Earth Sciences Project creating the A Brazilian national Earth Sciences Project creating the Geochronological, Geodynamic and Environmental Net. Geochronological, Geodynamic and Environmental Net.
- 27. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA The GeoChronos Net The GeoChronos Net SHRIMP LA-ICP-MS • University of São Paulo • Federal University of Pará • University of Brasilia • Federal University of RS
- 28. Laboratório de Petrologia Aplicada à Pesquisa Mineral – CPGG – IGEO – UFBA Ackn Ackn wledgments wledgments 510