Intro to Geochem L4

• What is the purpose of radiogenic isotope tracing?

  To use isotopes as markers of where magma comes from
• What do trace elements help model in geological settings?

  Partitioning behaviour and modelling
• What do major elements provide evidence for in igneous rocks?

  The origin and evolution of igneous rocks
• What do textures and reactions in metamorphism help constrain?

  How metamorphism occurs and what happened during the process
• Why do igneous and metamorphic processes require imagination?

  Because they cannot be easily visualized like sedimentary processes
• What is the significance of Bowen's reaction series?

  It predicts the mineralogy of different rock types as basaltic magma cools
• What does equilibrium crystallization involve?

  Crystal-poor magmas cooled rapidly
• How does fractional crystallization change magma composition?

  Crystals are removed from the remaining melt, evolving the magma
• What is the result of crystallization concentrating incompatible elements?

  It leads to the formation of ore minerals
• What are the key points regarding melting processes in igneous rocks?

  • Melting is partial
  • Plate tectonics contribute to melting
  • Subduction processes release fluids and melts
  • Basalt forms from mantle peridotite
• What is the significance of andesites in continental arcs?

  They form due to long storage and differentiation of multiple batches of magma
• What are major elements in rocks indicative of?

  Proportions of minerals and their chemistry
• What is the challenge with measuring trace elements in rocks?

  They are present only in low abundances
• What does Goldschmidt's classification deal with?

  Lithophile elements and their behavior in minerals
• What is the significance of ionic radius in mineral formation?

  It determines how ions can substitute for each other in a crystal lattice
• How can ions with different charges swap in a crystal lattice?

  Multiple substitutions must occur to maintain electrical neutrality
• What is the goal of experimental petrology?

  To understand how known rock compositions behave under heat and pressure
• What is the importance of avoiding sampling bias in analytical research?

  To ensure the samples are representative of the geological material
• What is the purpose of sample preparation in analytical geoscience?

  To get the sampled material into a form suitable for measurement
• What is in-situ analysis used for?

  To analyze trace elements directly in solid samples
• What is a common method for identifying specific elements in samples?

  1. ray diffraction
• What is the role of contamination in trace element measurement?

  It can affect the accuracy of the results
• What types of samples are commonly collected in analytical geoscience?

  Rock samples, water samples, and volcanic gas samples.
• What does "wet chemistry" refer to in analytical geoscience?

  Measuring material in solution.
• What is X-ray diffraction used for?

  Identifying specific elements and reconstructing the mineralogical make-up of a sample.
• What is X-ray fluorescence used for?

  Quantifying how much of different elements are in samples.
• What is gas chromatography used for?

  Analyzing organic compounds by vaporizing them.
• What is in-situ analysis?

  Analysis performed directly on the sample without removing it from its original location.
• Why is contamination a concern in mass spectrometry?

  It can affect the measurement of trace elements.
• What is the maximum particle size for crushed samples in mass spectrometry?

  Less than $100 \, \mu m$.
• What must be ensured regarding acids used in sample preparation?

  They must be very pure to avoid contamination.
• What is the purpose of blanks in wet chemistry?

  To quantify contamination and measure accuracy.
• What are reference materials used for?

  To calibrate instruments and ensure accurate measurements.
• What is sample-standard bracketing?

  Running standards to quantify accuracy and precision.
• What is a spike solution in geochemical techniques?

  A solution with a known concentration of elements or isotopes added to a sample.
• How is the limit of detection measured?

  By comparing standards of known concentrations against background noise.
• What is the significance of measuring isotopes in mass spectrometry?

  It helps determine the abundance of elements in a sample.
• What does the term "drift" refer to in analytical processes?

  Changes in instrument performance over time affecting measurements.
• What is the role of quality control in analytical geoscience?

  To ensure the accuracy and reliability of results.
• What are the main issues to consider during sample preparation and analysis?

  • Contamination
  • Consistency of procedures
  • Accuracy of measurements
  • Quality of note-keeping