CPG Basin Analysis & Structural Geology Flashcards

Which type of sedimentary basin forms primarily due to lithospheric extension and thinning?

Answer: Rift basin

Rift basins form where tectonic extension stretches and thins the crust, creating half-grabens and grabens that fill with sediment.

The petroleum system concept requires which of the following essential elements?

Answer: Source rock, reservoir rock, trap, seal, and overburden

A complete petroleum system requires source rock, reservoir rock, trap, seal, and sufficient overburden for maturation, along with the right timing of each.

Vitrinite reflectance (%Ro) is used in basin analysis primarily to assess:

Answer: Thermal maturity of source rocks

Vitrinite reflectance increases as organic matter is heated over geological time, making it the standard measure of thermal maturity for source rock evaluation.

In structural geology, a thrust fault is characterized by:

Answer: Hanging wall moving up relative to footwall at low dip angle

Thrust faults are reverse faults with dip angles less than 45°, where compression causes the hanging wall to ride up and over the footwall.

Which basin type is typically associated with the foreland of fold-and-thrust belts and is loaded by the weight of thrust sheets?

Answer: Foreland basin

Foreland basins form in front of orogenic belts where the lithosphere flexes downward under the weight of advancing thrust sheets, creating an asymmetric depocenter.

The 'oil window' in a sedimentary basin typically corresponds to vitrinite reflectance values of approximately:

Answer: 0.6–1.3% Ro

The oil generation window corresponds to %Ro values of approximately 0.6–1.3%, while higher maturities produce wet gas and then dry gas.