Normal faults-rifted continental margins

-form in extension

-typical for continental and oceanic lithosphere

-jargon (horsts, grabens, listric, detachment)

-are they low-angle?

-core complexes

-Example: Basin and Range, the best of all

-the way we think it works, mechanically

-balancing cross-sections

Can you spot the fault?

It’s low angle, but so are thrust faults:KEY: puts young (hanging wall) on old(footwall). The fault markers (slickenlinesEtc) are the same.

Terminology and mechanism.KEY ASPECTS:High-angle vs. low angle normal faulting; whichone generates more extension (S)? The formation of core complexesMajor detachment faults.How can we distinguish the low-angle normal faultingStyle from thrusting (if only geometry is available)?

Basin and Range- world’smost studied extensionalprovince-low-angle normal faulting prevails. Tibet-similar.

Breakaway zone; importance of a brittle-ductile transition

Inversion tectonics- normal faults become thrusts and inverse faults. A regional system formed in extension isforced to shorten.

How it might work

Important things about normal faults.

1. Fundamental to structure of continents and oceans.

Important things about normal faults.

2. Two different styles: the low-angle and high-angle.

Important things about normal faults.

3. Can take up as much extension as compressional orogens shorten.

Important things about normal faults.

4. You live in the most famous (and perhapsmost important extensional region-the B&R).

Important things about normal faults.

5. Extension is accompanied by big-time sedimentation-important for oil formation.

Important things about normal faults.

1. Fundamental to structure of continents and oceans.2. Two different styles: the low-angle and high-angle.3. Can take up as much extension as compressional orogens shorten.4. You live in the most famous (and perhapsmost important extensional region-the B&R).5. Extension is accompanied by big-time sedimentation-important for oil formation.