This one will be a little harder, so I will give THREE pictures instead of one.
First, the area:
Next, the detail I'm after:
And third, another example of the same phenomenon from the same region:
It is possible that you will have to guess at what this is to be able to search for documentation, so I will give a hint right at the start: These veins are NOT volcanic.
As always, the first person to post the position and whatever is interesting about the geology/hydrology/geowhatever in this location, wins the privilege of hosting the next WoGE.
Previous WoGEs are collected by Felix on his blog and a KML file.
-37.223°, -69.110° Toribia Asphaltit mine, Argentina. The asphaltit is out of a bitumen dyke, cutting through red continental strata of Late Cretaceous Sediments of the Neuquen Group. The dyke is parallel to (and within 1.5 km of) a chain of balsaltic spater -cones. [https://www.researchgate.net/publication/267758237_Radial_patterns_of_bitumen_dykes_around_Quaternary_volcanoes_provinces_of_northern_Neuquen_and_southernmost_Mendoza_Argentina]
SvarSlettThat was quick! :)
SlettOle I think you are the expert for this.
SvarSlettThe Neuquén basin is rich of organic-rich shales. The bitumen in our picture is in a dyke structure. I've read somewhere, that most of the bitumen veins in this area are related to dykes. Am I right, that cracks in the rocks were being filled by bitumen, which has matured by heat from nearby volcanos?
From "internal literature", volcanic heat has forced maturation of source rocks at shallow depths. Hot hydrocarbons have the collected and been expelled rather forcefully away, in most cases upwards but also in some cases downwards from the source area. Due to the heat, the host rock has fractured allowing the hydrocarbons to invade. Since this was "quick-made" and also at very shallow depths, the lighter hydrocarbons (if any were ever present) boiled off rapidly leaving heavy tarry asphaltite.
SlettThanks, now I got the full picture.
SvarSlettWoge592 can be found:
SvarSletthttp://woge-felix.blogspot.de/2017/01/where-on-google-earth-592.html