<p>How can a nearly pure silica bed with 250 m x 50 m x 1.5 m dimensions be interpreted in a volcanic/pyroclastic setting? Here is a photo of it.<a href="https://i.sstatic.net/ExcyK.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/ExcyK.jpg" alt="enter image description here"></a></p>

CC BY-SA 4.0
2019-03-04T20:50:52.860Z
My guess is that this rock is showing evidence of hydro-thermal alteration after the pyroclastic deposit was formed when heated groundwater / magmatic fluids flowed through the rock.
Earth Science Expatriate
CC BY-SA 4.0
2019-03-04T21:00:31.187Z
What's the stuff above and below the chert?
Gimelist
CC BY-SA 4.0
2019-03-04T21:58:06.940Z
I didn't observed contacting rocks. Note the blocky texture/structure and vesiculates/hollows/holes. The vesicules may transmit thermal waters.
Muharrem Yavuz
CC BY-SA 4.0
2019-03-07T08:10:42.493Z
Gary, what are the evidences of the rock made you think that it was hydro-thermally altered? What is the degree of the alteration (regarding severity/intensity)?
Muharrem Yavuz
<volcanology><pyroclastic-flows>
Interpreting an outcrop of a thick pure silica bed in a volcanic setting
Muharrem Yavuz
# Interpreting an outcrop of a thick pure silica bed in a volcanic setting

(Asked by: username_0 on 2019-03-04)

How can a nearly pure silica bed with 250 m x 50 m x 1.5 m dimensions be interpreted in a volcanic/pyroclastic setting? Here is a photo of it.[![enter image description here](https://i.sstatic.net/ExcyK.jpg)](https://i.sstatic.net/ExcyK.jpg)

**Tags:** volcanology, pyroclastic-flows

> **Comments:**
> **username_1**: My guess is that this rock is showing evidence of hydro-thermal alteration after the pyroclastic deposit was formed when heated groundwater / magmatic fluids flowed through the rock.  
> **username_2**: What's the stuff above and below the chert?  
> **username_0**: I didn't observed contacting rocks. Note the blocky texture/structure and vesiculates/hollows/holes. The vesicules may transmit thermal waters.  
> **username_0**: Gary, what are the evidences of the rock made you think that it was hydro-thermally altered? What is the degree of the alteration (regarding severity/intensity)?  

---

## 0 answers

