[Geysers] The role of geyserite in geyser plumbing (or "Who needs geyseri...

[TSBryan at aol.com]

With some snips taken out of Brian's original posting, here are a couple of 
 brief thoughts:
 
1. Clearly, "geyserite" (that is, silica) is not absolutely required as a  
plumbing system lining. Though mostly of rather small size, there are a few  
geysers/erupting things here and there that are lined with carbonate. 
Geyserite  is the more common material simply because these high-temperature 
systems tend  to occur in youthful volcanic areas where silica-rich rocks  
predominate. Also, there appear to also be some geysers that are not lined  with 
anything at all other than country rock. Like Norris (speaking of  
Steamboat!), where there is little to no geyserite in many of the features;  indeed, 
at Norris clays might play this role.
 
2. I think Brian hit on it where he said "...  that it acts to  reinforce 
and pressure-seal the main conduit against higher *external*  pressure..." 
There are several notable cases where geysers exhibit clear-cut  seasonal 
variations in their activity (Aurum; Fan & Mortar; Giant...)  because of, we 
presume, the influx of groundwater from the surrounding external  environment. 
So perhaps the key is that geysers aren't so much sealed in as they  are 
sealed out.
 
Scott Bryan
 
 
In a message dated 7/31/2013 6:27:17 P.M. US Mountain Standard Time,  
brdavis at iusb.edu writes:

 
Why do you need geyserite to ‘pressure seal a geyser’? 
Then I thought about the description of the role geyserite  plays in “
pressure sealing” the “plumbing systems” of geysers… and wondered  “why?” As 
near as I can tell, pressures never rises above hydrostatic.  Moreover, if 
the plumbing system was actually ‘sealed’, there would be no way  to recharge 
either water or energy to the system. So… 
1) Is the pressure always at or below  hydrostatic? 
2) If so, what role does a geyserite-lined system play (vs.  any other 
lining)? 
So far the best idea I’ve come up with is  that it acts to reinforce and 
pressure-seal the main conduit against higher  *external* pressure, after the 
geyser has erupted… but honestly that doesn’t  make a lot of sense to me, 
as water infiltrating from the walls seems to be  one way the conduits refill 
in the first place, and secondly voids in rock or  even semi-consolidated 
sediment can remain against hydrostatic external  pressure just fine on their 
own, no “armor cladding” needed. 
Brian  Davis

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