Cosmo Fundamentals Quiz

1. Which factors influence the production rate of cosmogenic nuclides at a given location?

a) Latitude and altitude
b) Earth's magnetic field strength over time
c) The amount of shielding of the sampled surface
d) The half-life of the cosmogenic nuclide (The half-life affects decay, not production.)

2. What are the primary production pathways for cosmogenic nuclides in surface rocks?

a) Spallation reactions with high-energy neutrons
b) Thermal neutron capture
c) Decay of uranium and thorium isotopes (These produce different radionuclides, not cosmogenic nuclides.)
d) Negative muon capture

3. Why is quartz the preferred mineral for 10Be and 26Al dating?

a) It has a simple and well-defined chemical composition
b) It is widely available in the Earth's continental crust
c) It has a high concentration of cosmogenic nuclides compared to other minerals (Quartz is preferred for its purity, not high nuclide concentration.)
d) Surface contaminants can be removed by chemical etching

4. When conducting surface exposure dating, which conditions must be met for accurate age determination?

a) The sample has been continuously exposed since deposition
b) There has been negligible post-depositional erosion
c) The cosmogenic nuclide concentration is at secular equilibrium (This applies only to samples that have been exposed for many half-lives.)
d) The sample is located at high altitude to maximize nuclide production (Altitude affects production rates, but high altitude is not a requirement.)

5. In an AMS system, how are molecular and isobaric interferences removed?

a) By using a gas stripper to remove electrons and dissociate molecules
b) By accelerating ions to high energies to separate atomic isobars in a nuclear detector
c) By using Faraday cups to selectively collect isobaric interferences (Faraday cups measure stable isotopes, not rare cosmogenic nuclides.)
d) By measuring isotope ratios with conventional mass spectrometry (Conventional mass spectrometry lacks the resolution needed to separate isobars.)

6. Which factors must be accounted for when calculating a 10Be surface exposure age from AMS data?

a) The 10Be/9Be ratio measured in the sample
b) The 10Be production rate at the sample location
c) The 10Be decay constant
d) The ratio of 10Be/26Al ratio in the sample (This is used for burial dating, not surface exposure dating.)

7. When using the “banana plot” to assess burial history, where do samples that have experienced prolonged burial typically plot?

a) On the zero-erosion line (This represents simple exposure history.)
b) In the steady-state erosion island (This represents surface exposure with constant erosion.)
c) Below the steady-state erosion island
d) In the forbidden zone (This is physically impossible and indicates analytical errors.)

8. What challenges arise when using 36Cl for exposure dating?

a) 36Cl can be produced via spallation, slow and fast muons, and thermal neutron capture
b) The presence of water in the sample environment affects neutron capture rates
c) 36Cl in whole rock is produced in multiple elements, each of which needs to be quantified.
d) 36Cl has a much shorter half-life than 10Be, making it unsuitable for long-term dating (While 36Cl's half-life is shorter, it is still useful for dating up to ~1 million years.)

9. How does the shielding effect influence cosmogenic nuclide production?

a) Shielding from topography reduces the cosmic ray flux at a sample site
b) Shielding corrections account for atmospheric density variations (Atmospheric effects are separate from topographic shielding.)
c) Shielding can be quantified using azimuth and elevation measurements of surrounding topography
d) Shielding is negligible for samples at high altitudes (Shielding corrections are still needed, regardless of altitude.)

10. What steps are necessary when interpreting cosmogenic nuclide data to avoid erroneous conclusions?

a) Ensuring accurate sample collection and minimizing contamination
b) Comparing surface exposure or burial ages with independent dating methods
c) Assuming all samples have a simple exposure history to simplify calculations (This is incorrect—many samples have complex histories.)
d) Evaluating uncertainties in production rates, erosion rates, and shielding corrections

Cosmogenic Nuclides

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Cosmogenic Nuclides

Cosmo Fundamentals Quiz

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