ASBOG Economic Geology and Energy 5

Question 1

Sedimentary exhalative (SEDEX) deposits form when:

Accepted Answer

Metal-rich hydrothermal brines vent onto the seafloor and precipitate sulfides within sediments

Answer

SEDEX deposits form when hydrothermal brines exhale onto the seafloor and precipitate stratiform Pb-Zn-Ag sulfides within marine sediments.

Question 2

Which factor MOST directly controls the economic viability of a phosphate rock deposit?

Accepted Answer

P2O5 content and proximity to agricultural markets

Answer

The P2O5 grade of the ore and transportation costs to fertilizer markets are the primary economic factors for phosphate mining.

Question 3

In the context of oil sands (tar sands), the hydrocarbon extracted is called bitumen, which differs from conventional crude oil primarily because it:

Accepted Answer

Is too viscous to flow without heating or dilution

Answer

Bitumen has very high viscosity (API gravity <10°) and cannot flow under reservoir conditions without thermal treatment or dilution with lighter hydrocarbons.

Question 4

The 'critical zone' of a Bushveld Complex-type layered mafic intrusion is significant because it hosts:

Accepted Answer

Platinum group element (PGE)-bearing reefs such as the Merensky Reef

Answer

The Critical Zone of the Bushveld Complex contains the Merensky Reef and UG2 Reef, which are the world's dominant sources of platinum group elements.

Question 5

Carbon capture and storage (CCS) for CO2 sequestration is BEST suited to which geologic setting?

Accepted Answer

Deep saline aquifers or depleted oil and gas reservoirs with impermeable caprock

Answer

Deep saline aquifers and depleted hydrocarbon reservoirs are preferred CCS targets because they have proven trapping capacity and seal integrity.

ASBOG - Association of State Boards of Geology Practice Test

ASBOG - Association of State Boards of Geology Practice Test

ASBOG Economic Geology and Energy 5