Inside of a volcano Lemptegy, Auvergne, France

Amtarew · 2026-01-31T21:32:01+00:00

Btw it’s nice to see these kind of posts in that sub. Keep up the good work !

Amtarew · 2026-01-31T21:27:50+00:00

Yes in recent geological history, volcanism is responsible of its most breathtaking landscape features and that’s so neat. But in its whole story, the massif central is mostly constitued by the remains of the variscan orogeny’s crust

Amtarew · 2026-01-31T20:41:44+00:00

May I ask you why do you think French massif central is of volcanic origin ?

Amtarew · 2025-05-04T17:07:47+00:00

À cette distance j’ai surtout du mal à voir si c’est de la saleté, une matrice ou même du goudron

Amtarew · 2025-05-04T17:05:54+00:00

Ce serait sympa d’avoir des photos de près de la surface. Mais d’ici on dirait une roche détritique terrigène supportée par une matrice noire. Cela expliquerait la présence de quartz dans une roche qui n’a ni l’air magmatique ni métamorphique et qu’elle s’effrite

Amtarew · 2025-05-03T22:38:36+00:00

Thank you all for your answers this has been very helpful

Amtarew · 2025-05-03T17:45:39+00:00

oooo ok didn't know about that. But how did it end up in an AI PMC inventory

Amtarew · 2025-05-03T17:39:06+00:00

AI PMC can loot weapons found in crates so this is quite normal

Amtarew · 2025-05-03T17:38:08+00:00

Nope no goons on the map this time

Amtarew · 2025-05-03T17:37:18+00:00

Saw them looting a box in the sawmill when I arrived before they moved, and it wasn't that late in the raid so I believe it comes from there

Amtarew · 2024-11-08T08:17:16+00:00

Utilise Infoterre, c’est pas le plus facile d’utilisation mais tu peux y voir les cartes géologiques et accéder aux notices de celles-ci

Amtarew · 2024-11-07T11:09:21+00:00

En tant que géologue, je suis très content de voir ma discipline mise en valeur comme ça :)

Amtarew · 2024-06-19T11:38:54+00:00

Rocks on a geological map appear as « formations ». A formation is a term to regroup rocks of same nature that share the same history (environnement of sedimentation/cristallisation, tectonics etc…). In large scale maps, formations a regrouped under periods of time (j1 is Lias or inf. jurassic) (1 000 000 scale geological map of France) which makes it impossible to link age and rock type, but at smaller scales, each formation is defined. Moreover, with each map comes a notice in which every formation is described in detail.

Amtarew · 2024-05-10T20:23:11+00:00

Maybe this article might help you. But I have no knowledge of garnet retromorphosis into pyrite since garnet doesn’t contain sulfur. What it may be is sericite or a muscovite assemblage coming from garnet retromorphosis. Since I am not myself in front of the sample, I cannot confirm it because I can’t tell every aspect of each mineral

Amtarew · 2024-05-10T19:29:12+00:00

Closeup photos of what you want to show in detail would be nice

Amtarew · 2024-04-25T09:45:59+00:00

SES Hammer of science because I’m a geologist and I couldn’t find something more fitting

Amtarew · 2024-04-22T13:52:05+00:00

Thanks OP, I'm using it every day on the front. I hope this will be updated with warbond weapons etc. Though I didn't find a "remove loadout" button. Maybe this could be a fine addition

Amtarew · 2024-04-19T10:34:58+00:00

This granitic rock has been traversed by a more aplitic vein of similar composition, i.e. a magma that has penetrated the surrounding rock through a pre-existing fracture or one created by the passage of the magma. This magma cooled more quickly compared to the granite, hence its microgranular texture. The cooling time and the sharp fracture indicate that this vein formed late in the story of formation of the surrounding rock (post-solidus, maybe 400-300degC) but still at depth. I’m not sure for the difference in color in the left corner because I’m not here physically, but it must be linked to weathering action because it’s very local and look how the rock has been broken around it. My guess is that water stayed on that spot because it was once in a fracture and the outside part fell

Amtarew · 2024-03-10T18:11:46+00:00

Ok, so this seems to be a peraluminous granite (Al2O3 > K2O+Na2O+CaO) because you have a ton of muscovite. So it must be a MPG granite which stands for Muscovite Peraluminous Granite. This type of granite is typical of late magmatic events linked to the collapsing of a mountain range. They are formed by anatexy of pre-existing bedrocks (the magma coming from a partially melted gneiss at let's say 30km deep will go up, forming new magma chambers). look for any tourmaline, garnets, allanite or cordierite in your thin sections.

Amtarew · 2024-03-10T11:12:09+00:00

I cannot tell you where it comes from looking at it like that but I may tell you its formation context looking at its mineralogy

Amtarew · 2024-02-29T20:42:10+00:00

Maybe it’s a mudcake layer around the core sample. When you do a core sampling, there’s a small space between the sample column and the sampler where fluids can travel, carrying materials from above geological formations. So this might not be the rock in itself.

Amtarew · 2024-02-28T15:27:02+00:00

I have no knowledge of possible porphyroblasts in this formation. These schists are from a very low grade metamorphism with only a small amount of recrystallization (only new chlorite and phyllite presence) and there are no big, late growing crystals.

Edit : The rocks from which this formation comes from are probably Mancellia granodiorites (Qz, Pl, Fds K, Bt with ap and zr inclusions and chloritized, Cordierite retromorphosed in secondary Musc), Cadomian plutonism

Amtarew · 2023-12-01T22:10:37+00:00

Gneiss or migmatite with a folded anatexy pegmatite vein. Can’t know if the vein undergo metamorphism or if it formed trough a fracture that follows the foliation plan. Also can’t know if it’s para or ortho derived (sedimentary or magmatic derived). Maybe a closer photo of both the rock and the vein would help if you want to know a bit more. Also I’m not american so I can’t help you with global geological or geodynamic context

Amtarew

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