

Oldest Body of Seawater Found in Giant Crater - mikehotel
http://news.nationalgeographic.com/news/2013/11/131120-oldest-seawater-chesapeake-bay-crater-science/

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jofer
The way this article is written is very misleading.

This is not in any form or fashion the "oldest body of seawater yet found" nor
is it unusual to find ancient trapped seawater.

"Connate water" is water trapped in sediments at the time of their deposition.
Whether or not connate water is preserved in large quantities depends on the
local permeability structure of the sediments and the regional hydrology.
However, it's very common for connate water to be preserved more or less
indefinitely (particularly in shales).

In other words, there's a _lot_ of trapped seawater almost everywhere you
look.

What's unique about this isn't that there's trapped seawater, and it's
certainly not the oldest connate water discovered (nor do the authors of the
actual article claim that it is).

It's unique because:

A) it's direct evidence that the Central Atlantic had a very high salinity
even long after it opened. (The authors are using the term "north atlantic"
for some strange reason, but this segment is more commonly referred to as the
"central atlantic")

B) The connate water survived a metorite impact without being highly
disturbed.

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mikehotel
Editor's summary from the Nature journal:

 _Geologists and oceanographers generally have to rely on indirect evidence
from the analysis of solid materials in deep sediment cores when estimating
temperature and salinity levels of the ancient oceans. But now a team from the
US Geological Survey has identified a body of underground water that is
actually a remnant of a past ocean water, a body of Early Cretaceous North
Atlantic sea water. Deep drilling at the site of the Chesapeake Bay impact
crater has yielded groundwater with an isotope and chemical composition
signature that together with model analysis suggests that it was trapped in
the sediments before the impact occurred around 35 million years ago. The
water may have lain undisturbed for much longer: it has an average salinity of
about 70 parts per thousand, twice that of modern sea water, and is probably
100–145 million years old._

[http://www.nature.com/nature/journal/v503/n7475/full/nature1...](http://www.nature.com/nature/journal/v503/n7475/full/nature12714.html)

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mtdewcmu
What struck me is the age of the oldest known seawater. That's on the order of
2% of the age of the earth. There are plenty of rocks that are much older. I
guess seawater doesn't keep very well.

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fhars
For one, rocks don't evaporate in the sunlight at our distance from the sun.

~~~
mtdewcmu
That's true. But rocks erode at a rapid pace in comparison to the age of the
earth. Apparently, very little is left for geologists to study from earlier
than about 1 billion years ago. And there is a tremendous amount of
groundwater deep underground, with some of it trapped by rock formations.

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mikehotel
Looks like my uneditorialized title was edited to remove the "mind blowing
discovery" prefix. I thought HN policy was to use the title as published. In
any case, thanks for the edit. I would have done it except for my apparent
confusion regarding best practices.

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ams6110
_...the team was able to figure out the rough age of the ancient water_

Is there significant creation of "new" water on the earth? I suppose water
produced in combustion of hydrocarbons would qualify, but seems to me that's
tiny compared to the existing amount of water, which is all roughly the same
age (ancient) and is just continually cycling between vapor (evaporation) and
liquid (clouds/rain) state.

This discovery is simply water that has been in isolation for a long time.

~~~
mikehotel
Recent discoveries of isolated water have lead to investigations of new
organisms (see [http://www.nature.com/news/russian-scientist-defends-lake-
vo...](http://www.nature.com/news/russian-scientist-defends-lake-vostok-life-
claims-1.12578)). This appears to be much older, but perhaps not as well
isolated as Lake Vostok since there appears to be a connection with increased
groundwater salinity in the area.

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imahboob
I hate it when these blog journalists don't event know how to read scientific
papers

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strathmeyer
Mirror??

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gt565k
right click => inspect element => set style to "display:none" on the popup and
overlay, and you're good to go.

