Reverse faults do form in extensional tectonics systems, however these faults in general would be fairly steep. See an example from a sandbox experiment in this link.

https://blogs.agu.org/thefield/2020/04/07/interesting-reverse-faults-in-a-simple-extensional-sandbox-model/

Inversion is also common and low angle reverse faults would then be expected. See the book chapter attached which gives a good overview and helpful references.

Yes, it is possible in a couple of instances: speaking theoretically (1) along restraining bends in the transfer faults that connect extensional faults, (2 ) at places in the displacement field where changes in direction form 'kinks' or rapid changes in the direction blocks are moving, (3) late in an extensional episode where the blocks are changing displacement rate differentially to each other. This last one i think is one cause of inversion when the inversion is close in time to the extension on which it acts. I call this 'syn-kinematic' inversion

Yes, check out my research gate list for 'Karoo-related basin-forming fault systems of northern Namibia'. Especially regarding the Waterberg thrust. It would not paste into this box.

In addition to the aforementioned comments thrusts (

Hi Jens,

Thank you for your attention and Thank you in advance for your help.

" In Orogenic collapse The process that occurs when thickened crust in a collisional orogen weakens and starts to sink under

its own weight. Effectively, gravitational loads cause horizontal extensional strain to develop. In some cases, extension is coeval with thrusting (synorogenic collapse)," ..earth structure (an introduction to structural geology and tectonics)

by van der Pluijm and Marshak 2004

Conrad, Jim and Jens have beautifully addressed the matter of accomodating movement over different segments of a fault. I myself am going to read more about it.

But also, I was thinking about toe thrusts, fold-thrust systems formed during the opening of a rift. They are not extensional, of course, but they do form inside an extensional system.

Let's try to imagine this situation:

There we have our original, perfectly peaceful sedimentary layers. Maybe limestone, shale and sandstone? It's up to you (just be reasonable, don't go putting a gneiss over a sandstone).

Then, the continent breaks. Some faults are formed.

Imagine you have 2 consecutive, perfectly N-S striking and E-dipping, normal faults. We'll call them fault 1, to the West, and fault 2, to the East. They divide our section in 3 parts: one to the west, one in the center (between the faults) and one to the east. Let's go wild and call them A, B and C (in that order), shall we?

As our faults dip Eastwards, gravity will bring our blocks to slide also towards East. Makes sense?

Now focus on the center block (B). Its Western border (B-W) is the hanging wall over fault 1, while the Eastern border (B-E) is the footwall under fault 2.

So the B-W is sliding down, but the B-E cannot just adjust itself accordingly, because it is limited by the hanging wall (C) above fault 2.

This means there is some very heavy weight coming down from the West. So, locally, you have actually compression in the East, even though you are inside a globally extensional system. So there you have it: a fold-thrust system can be formed, inverse faults and all.

van der Pluijm and Marshak (2004) is actually a good source, as Rabee mentioned. I would also reccommend Nemčok et al (2005) and Poblet and Lisle (2011)

Henrique,

Good example--thanks--in a concrete example, you have just described a situation where the displacement field is governing the instantaneous stress on the planes, and thus isolated those transient effects from the overall 'stress field' and from the overarching structural style is you want to call it that.