Where did the O2 associated with red mesozoic sandstones com

  • Thread starter linnorma
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The other way round: The fact that these sandstones are reddish does not say anything about the oxygen concentrations in the atmosphere, except that at least at that time (since then the supercontinent broke apart and the previous oceanic areas were again flooded, so that the sandstone deposits were again covered by water) the oxygen concentrations must not have been too low (if they had been, the iron in the sediments would have been reduced and not oxidized, so that the sediments would not have been reddish, but greenish or blackish).
  • #1
linnorma
red mesozoic sandstones and atmospheric oxygen

There is a recent article describing high CO2 concentrations at Permo-Triassic boundary. How did atmosphere change to high O2 responsible for Mesozoic red sandstones in interior USA?
 
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  • #2
linnorma said:
red mesozoic sandstones and atmospheric oxygen

There is a recent article describing high CO2 concentrations at Permo-Triassic boundary. How did atmosphere change to high O2 responsible for Mesozoic red sandstones in interior USA?
Please post a link to the article so that we can see what you are referring to.

Thank you. And yes, I moved your posts here from "Member Introductions only - No questions".
 
  • #3
I am not sure whether the red colour of the sandstones from that timeperiod is primarily due to elevated oxygen concentrations. Rather, after the collision of Gondwana (continent formed from what is nowadays africa ad south america) and Laurussia (Northern America and Russia formed a common continent, too) in the Hercynian orogenesis (upper Devon, lower Carbon) a new supercontinent called Pangaea was formed. Relicts from this collisions are e.g. the appalachians in US and the e.g. the Harz mountains in Germany (whence the name Hercynian). One consequence of the formation of this supercontinent is that vast regions of both Europe and Northern America, which in former times had been basically consisted of mud deposited in the shelf regions of large oceans often under oxygen deficient conditions, or plutonic intrusions like granite (also formed under reducing conditions), which formed during the collision of the continents, where now elevated above sea level and inside a huge continent with a continental climate. The errosion of these mountains which oxygen saturated water in an otherwise dry and hot climate lead to the reddish sandstone deposits from that period ("Rotliegendes" in the Permian and "Buntsandstein" in the lower Triassic).
 

1. Where did the O2 associated with red mesozoic sandstones come from?

The O2 associated with red mesozoic sandstones most likely came from photosynthesis by ancient plants and cyanobacteria in the Earth's atmosphere. This process produces oxygen as a byproduct, which then became trapped in the sandstone layers over time.

2. Why are red mesozoic sandstones associated with high levels of O2?

The red color of mesozoic sandstones is caused by the presence of iron oxide, also known as rust. This iron oxide was formed when the sandstone was exposed to high levels of oxygen in the atmosphere, indicating that there was a significant amount of O2 present during the time of its formation.

3. How do scientists know that red mesozoic sandstones were formed in an oxygen-rich environment?

Scientists can determine the presence of oxygen in ancient environments by analyzing the chemical composition of the rocks. The high levels of iron oxide in red mesozoic sandstones indicate that there was a significant amount of oxygen present during their formation.

4. Could the O2 associated with red mesozoic sandstones have come from another source?

While it is possible that the O2 associated with red mesozoic sandstones could have come from another source, such as volcanic activity or meteorites, the most likely explanation is still photosynthesis by ancient plants and cyanobacteria. This is supported by the presence of other organic compounds and fossils in the sandstone layers.

5. How does the presence of O2 in the atmosphere affect the formation of red mesozoic sandstones?

The presence of O2 in the atmosphere is necessary for the formation of red mesozoic sandstones. Without oxygen, the iron minerals in the sandstone would not have been oxidized and the rocks would have a different color. Additionally, the high levels of oxygen in the atmosphere during this time likely played a role in the evolution and diversification of plant and animal life on Earth.

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