File talk:Andesitic dyke Morro Solar.jpg

Hydrothermal weathering

@Hornstrandir1: What criteria do you employ in order to put this file in the (IMHO doubtful) category Hydrothermal weathering? --Gretarsson (talk) 23:02, 20 June 2019 (UTC)

The hydrothermal alteration is to be seen in the picture in the different colouring of the rocks over the dyke. Also the rocks are breaking down/eroding easier around this (coloured) area, which also shows up in the picture.Hornstrandir1 (talk) 23:06, 20 June 2019 (UTC) I would understand hydrothermal weathering as a consequence of hydrothermal alteration (heat, fluids, gasses, chemical processes changing the rock which then breaks down easier), but would you say that it is just the same process and as such the category of hydrothermal weathering would be superfluous? Hornstrandir1 (talk) 23:19, 20 June 2019 (UTC)

Example for increased rock resistance by hydrothermal alteration along joints

Weathering and hydrothermal alteration are two different things that shouldn’t be confused, even though some hydrothermal processes may have a similar effect on rock resistance or even include the same alterations as weathering has/does. Hydrothermal alteration is mediated by hot mineral-loaden watery solutions and occurs in the vicinity of magmatic activity, which can be near-surface, deep underground or even deep in the ocean floor. It belongs to the rock-altering processes that are subsumed under the term diagenesis. (Chemical) weathering is a process mediated by cold surface waters and thus occurs only at the surface or in near-surface bedrock. Both have an effect on the vulnerability of the bedrock to erosion, but in fact every diagenetic process in some way will have an effect on geomorphology. Diagenesis, however, can also strengthen the rock an make it less vulnerable to erosion (see photograph to the right) whereas weathering, by definition, always will weaken the rock. Hence I think the Category:Hydrothermal weathering is not only superfluous but it’s a “bad” category because the term “hydrothermal weathering” mixes two different things that shouldn’t be mixed. --Gretarsson (talk) 11:59, 23 June 2019 (UTC)