ASBOG ASBOG - Association of State Boards of Geology Geochemistry and Soil Science Questions and Answers 2

Question 1

In geochemical exploration, what is the 'threshold' concentration?

Accepted Answer

The upper limit of background values above which concentrations are considered anomalous

Answer

The maximum concentration found anywhere on a site

Answer

The detection limit of the analytical instrument

Answer

The average of all samples collected

Question 2

The Unified Soil Classification System (USCS) uses two-letter symbols such as SP, ML, and CH. What does the first letter indicate?

Accepted Answer

Primary grain size group

Answer

Plasticity class

Answer

Soil color

Answer

Permeability class

Question 3

Sandy soils have higher hydraulic conductivity than clay soils primarily because:

Accepted Answer

Sand has larger pore spaces allowing faster water flow

Answer

Sand particles are more chemically reactive

Answer

Clay contains more organic matter

Answer

Sand particles have higher surface area per unit mass

Question 4

Carbon-14 isotopic dating is effective for determining the age of groundwater up to approximately how many years?

Accepted Answer

40,000 years

Answer

5,000 years

Answer

500 years

Answer

500,000 years

Question 5

What is diagenesis in the context of sediment geochemistry?

Accepted Answer

Physical and chemical changes in sediments after deposition but before metamorphism

Answer

High-temperature metamorphic recrystallization

Answer

Erosion of pre-existing sedimentary rocks

Answer

Formation of igneous intrusions within sedimentary sequences

Question 6

Which laboratory technique bombards a rock sample with X-rays to determine major and trace element concentrations?

Accepted Answer

X-ray fluorescence (XRF)

Answer

Mass spectrometry (ICP-MS)

Answer

Atomic absorption spectroscopy (AAS)

Answer

Neutron activation analysis (NAA)