Lecture 3: Sedimentary basins

Question 1

What types of divergent plate margin basins do we have?

Answer 1

Continental rift zones (narrow)
Aulacogene basins
Continental rift zones
Oceanic rift basins
Open ocean passive-margin basins

Question 2

Describe the origin and faulting in continental rift margins

Answer 2

Large scale mantle convection results in regional updoming and regional flood vulcanise
Extensional failure of crust creates listric normal fault system with subsided/rotated half grabens

Question 3

What could cause widening to form central rift graben in continental rift zones?

Answer 3

Rupturing of crust

Spreading ridge in an oceanic basin

Question 4

What are the environments and fancies of continental rift zone?

Answer 4

Alluvial fan, fluvial, lake

volcanism

Question 5

Give three examples of continental rift zones

Answer 5

East Africa rift zone
Rio Grande rift
Rhine graben

Question 6

What are Aulacogene basins?

Answer 6

Narrow continental rifts which do not evolve into spreading ridge oceanic basins, e.g. North sea basins

Question 7

What is the dominant facies and provenance of aulacogene basins?

Answer 7

Initial alluvial fan, fluvial, lake facies

Provenance - continental mixed e.g. plutonic, metasedimentary and marine carbonates

Question 8

What are oceanic rift basins?

Answer 8

Initially narrow (e.g. Red Sea): May evolve into open oceanic basins

Question 9

What is the dominant facies of oceanic rift basins?

Answer 9

Alluvial fans, fan deltas, shoreline narrow shelf, slope, abysmal plain
Mixed continental, volcanic, shelf + oceanic carbonates

Question 10

How do open ocean passive margins evolve?

Answer 10

Evolves from oceanic basins
Becomes passive margin basins when MORs
Half graven system evolves into coastal plain-continental shelf and slope