When and How did the oceans become Salty?
Jan 16, 2019 8:51:21 GMT -5
pauls, fishnpinball, and 3 more like this
Post by 1dave on Jan 16, 2019 8:51:21 GMT -5
cosmosmagazine.com/chemistry/why-is-the-sea-salty
forum.cosmoquest.org/showthread.php?93186-Questions-about-our-Oceans-and-their-origin&s=87cd02560d5c88d92048164f977134ce
. . .
www.lpi.usra.edu/lpi/contribution_docs/LPI-001423.pdf
Yasunori Miura's article begins on page 35.
It is estimated there is enough salt in the world’s oceans to cover all the planet’s land surfaces with a layer about 40 stories thick. But seawater wasn’t always so salty; when the Earth’s oceans first formed about 3.8 billion years ago, as the surface of the planet cooled enough to allow water vapour to liquify, the oceans were mostly fresh water. So where did all the salt come from?
forum.cosmoquest.org/showthread.php?93186-Questions-about-our-Oceans-and-their-origin&s=87cd02560d5c88d92048164f977134ce
Thread: Questions about our Oceans and their origin
jlhredshift: I was studying the composition of igneous rock types and it struck me that chlorine was not a constituent. Igneous rocks do not contain enough chlorine to explain our salty oceans. Therefore, weathering of those rocks does not explain the the chlorine content of those oceans. Time went by and I came across this statement by Dr Mark McMenamin in his book, co-authored with his wife Dianna, Hypersea, on page 24:
This brought the question of the salt content of our oceans to my thinking once again. Now, normally McMenamin cites his books very thoroughly, but not this particular passage in this regard. Searching then revealed this paper on the Lunar and Planetary Institute web page by Y. Miura:
IMPACT ORIGIN OF CHLORINE-BEARING MATERIALS OF SALTY SEA-WATER OF EARLY EARTH, COMPARED WITH THOSE ON MARS AND THE MOON
This is a short paper and on page two is this chart:
OK, but I still have questions.
Are Na and K in equilibrium in the ocean today; in the past or deep past?
I assume that chlorine as a gas or free ion in the atmosphere is too heavy to escape and the amount of chlorine on this planet is the total accumulation of all extraterrestrial impacting bodies since Earth formation, is that correct?
Is it truly tenable that the mineral content of the ocean has remained reasonably constant for 700 million years as McMenamin suggests?
What is the chemical path for chlorine from supernova to impact with our atmosphere.
There is evidence that rock weathering rates increased with the colonization of the land by plants during the Devonian; was there a ready supply of chlorine to react with the additional Na and K or did the extraterrestrial sources of chlorine eventually catch up to the weathering rate, or was it always in step.
I have oversimplified, I am sure, for the sake of brevity, but, please....
jlhredshift: I was studying the composition of igneous rock types and it struck me that chlorine was not a constituent. Igneous rocks do not contain enough chlorine to explain our salty oceans. Therefore, weathering of those rocks does not explain the the chlorine content of those oceans. Time went by and I came across this statement by Dr Mark McMenamin in his book, co-authored with his wife Dianna, Hypersea, on page 24:
... for the last 700 million years there has been little change in the proportions of the major ions of marine water. Good evidence now exists that the chemical composition of the oceans has stayed pretty much constant for a long time.... The use of oxygen isotope variations to determine ancient seawater temperature, a proven technique, assumes constant marine salinity for hundreds of millions of years.
This brought the question of the salt content of our oceans to my thinking once again. Now, normally McMenamin cites his books very thoroughly, but not this particular passage in this regard. Searching then revealed this paper on the Lunar and Planetary Institute web page by Y. Miura:
IMPACT ORIGIN OF CHLORINE-BEARING MATERIALS OF SALTY SEA-WATER OF EARLY EARTH, COMPARED WITH THOSE ON MARS AND THE MOON
This is a short paper and on page two is this chart:
1) Chlorine (Cl) concentration: Fusion crusts of Meteorites (in Air of Earth; craters on Mars, & meteorite fragments on the Moon)
2) Distribution to the surface: Huge impacts to collect Cl over surface (in Air of Earth; craters on Mars)
3) Rain-fall to form salty ocean water: Rain-fall by cooling from hot vapor, & Melting to salty ocean water (mainly on the Earth)
Fig.4. Process to form salty sea-water from meteoric origin
of chlorine element on Earth, Mars and the Moon.
2) Distribution to the surface: Huge impacts to collect Cl over surface (in Air of Earth; craters on Mars)
3) Rain-fall to form salty ocean water: Rain-fall by cooling from hot vapor, & Melting to salty ocean water (mainly on the Earth)
Fig.4. Process to form salty sea-water from meteoric origin
of chlorine element on Earth, Mars and the Moon.
OK, but I still have questions.
Are Na and K in equilibrium in the ocean today; in the past or deep past?
I assume that chlorine as a gas or free ion in the atmosphere is too heavy to escape and the amount of chlorine on this planet is the total accumulation of all extraterrestrial impacting bodies since Earth formation, is that correct?
Is it truly tenable that the mineral content of the ocean has remained reasonably constant for 700 million years as McMenamin suggests?
What is the chemical path for chlorine from supernova to impact with our atmosphere.
There is evidence that rock weathering rates increased with the colonization of the land by plants during the Devonian; was there a ready supply of chlorine to react with the additional Na and K or did the extraterrestrial sources of chlorine eventually catch up to the weathering rate, or was it always in step.
I have oversimplified, I am sure, for the sake of brevity, but, please....
. . .
cran
No argument there ...
Originally Posted by jlhredshift
As one of your sources indicate, an inventory and age of existing salt deposits needs to be determined more accurately.
As one of your sources indicate, an inventory and age of existing salt deposits needs to be determined more accurately.
No argument there ...
www.lpi.usra.edu/lpi/contribution_docs/LPI-001423.pdf
Yasunori Miura's article begins on page 35.
Introduction. There are few reports on major origin of salty taste of sea water in composition. However sea water contains high amount “chlorine”, together with sodium ion. Chlorine element of carbonaceous meteorite is higher than the crust of the Earth [1,2], though there are no chlorine-bearing mineral connected to major supply on the Earth. Recently auther (YM) found “chlorine-bearing minerals on fusion crust of meteorites” fallen to the Earth, not only found on with rocks on surface (Kuga, Carancas, and Mihonoseki) but also collected after air explosion by meteoritic shower without any mixing of rocks on the surface (Nio chondrite).
If chlorine element is concentrated in meteoritic melting in air from primordial Earth with huge meteoritic impacts, then rain drop from warm atmosphere is considered to be mixing with such chlorine minerals on melted meteorites to produce salty taste of ocean water finally [2]. The purpose of the present paper is to elucidates chlorine from meteorites finally to produce ocean water with salty taste.
If chlorine element is concentrated in meteoritic melting in air from primordial Earth with huge meteoritic impacts, then rain drop from warm atmosphere is considered to be mixing with such chlorine minerals on melted meteorites to produce salty taste of ocean water finally [2]. The purpose of the present paper is to elucidates chlorine from meteorites finally to produce ocean water with salty taste.
