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Phytoplankton Bloom

15 October 2022

A study in Geophysical Research Letters [2022], see https://www.doi.org/10.1029/2022GL099293 … and https://phys.org/news/2022-10-tonga-volcano-eruption-life-rapid.html … claims the submarine volcanic explosion in Tonga last January [2022] led to a remarkable bloom in microscopic marine life forms – just 48 hours after the blast. Scientists have determined that volcanic ash was likely the most important source of nutrients responsible for the phytoplankton growth.

Phytoplankton are tiny photosynthetic organisms that produce oxygen and are the base of the marine food chain, we are told. These microbes are usually limited by the low concentration of nutrients dissolved in the oceans but can increase rapidly when nutrients become available. Even though the eruption was submarine a large plume of ash reached a height of tens of kilometres high in the atmosphere. The ash fell back out of the sky and provided nutrients that stimulated the growth of phytoplankton. The ecosystem quickly responded to nutrient fertilisation.

What attracted me to this study was the possibility it might shed light on the geological chalk deposits of the Cretaceous. In particular, the upper chalk layer is very white and pristine, and therefore there is the possibility it formed fairly quickly – if not very quickly  [from a plankton bloom]. That would of course be challenged by uniformitarian gradualists wherein the chalk layer is said to have formed over millions of years. If so, how did it maintain its very white nature, made up of billions of shells of plankton? However,  to form quickly it would require a lot of volcanic activity in order to fertilise the oceans. A recent study actually claims there was an awful lot of volcanic and seismic activity generated by the K/Pg boundary event, an asteroid strike [see article post last week]. That volcanic activity went on for a very long time as the earth continued to shake in response to the asteroid that embedded itself into the ground at Chicxulub in the Yucatan. The problem here of course is that the Cretaceous marks the close of the dinosaur age  – and the boundary layer is the terminus point of the Cretaceous. It would require sedimentary layers both sides of the boundary layer to be regarded as being laid down immediately. Is that viable as an idea?

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