13 June, 2009

The Accretionary Wedge #17: The Time Warp!

One of the main problems in ore geology just like in most other subdivisions of geology is that we always and only see the final result. We are never there watching it from start to end. A very displeasing obstacle to really understand what happened.

But now - thanks to Lockwoord from Outside the Interzone - I have the tool I need to solve what bothers me: A Time Warp generated by the lastest edition of the Accretionary Wedge!

There are plenty of places, events and processes that would be fantastic to watch with my own eyes as they unfold. I'd really love to see if Snowball Earth really was a snowball or sample the very first living cell to probably roam the oceans. Also a small detour to early Mars while it was still warm and wet and friendly to life would sound like a great destination.

But actually I want to go elsewhere. I want to watch an ore deposit form. I want to see it from start to end. To narrow it down I want to be there while the Silesian Mississippi Valley Type district forms. This is not only the largest MVT Pb-Zn district of the planet with 730 Mt of ore but also there is evidence that the largest district of its kind was formed in an increadibly short amount of time! In the hypogenic karst cavities of the Silesian deposits you can find speleothems (see image) growing up and downwards. The point is they don't grow vertically up and down - they show indication of growing into the direction of fluid flow! You heard it right. These dripstones are made from Galenit, Spalerite and other ore minerals growing inside a pipe that the hydrothermal fluid must have been rushing through. There are estimates that the entire ore district formed in less than 50.000 years with some investigators arguing the time of formation could be as little as 5.000 years or less. Certain parts must have literally formed in the course of days and hours with giant streams of hydrothermal metal-rich fluids moving through the cracks and fissures of the host-rocks.

Sulfide speleothem from the Olkuze mine
(Source: Scanned from Conference handout SEG workshop on the Geology of Pb-Zn Ore Deposits, Lima, Peru, 2008. Image from chapters of David Leach)

That would be so cool. To sit right in those caves in a dry spot and literally watch galenite and sphalerite stalacties and stalagmites grow over night.

Not to forget I also want to take a look above ground. You may know there is a relationship between the palaeogeographic position, the palaeoclimate, mountain building processes and the formation of large carbonate-hosted MVT deposits. A hydrological test with tracers would be cool. Seeing where does the water really come from. What is the real flowpath? How are the precipating ores replacing the surrounding carbonates? I want to see and feel it first hand on.

Thats why I want a time warp.


Lockwood said...

Logged and queued. That is a beautiful bit of ore, from a MVT PbZn deposit I wasn't even aware of. This is going to be a great trip!

Callan Bentley said...

If you sampled the very first living cell to roam the oceans, wouldn't that mean that all you and me and everything else living on Earth (descended from that cell) would cease to exist?


Lockwood said...

@ Callan- I was thinking the same thing. Let's get a good stable population before we go harvesting our ancestors!

Lost Geologist said...

Well, true, but I am considering this more from a hypothetical point of view. Perhaps we could just make some non-destructive tests.... :-D