Tuesday, 16 November 2021

Deep Mantle Mineral Found in Diamond

Deep Mantle Mineral Found in Diamond 

THIS ARTICLE tells us of a newly named mineral found as an inclusion in a diamond. The mineral had been made in high pressure, high temperature laboratories but the authors are among the first to find it in nature and the first to, officially, name it. 

The composition is the same as wollastonite (see HERE) CaSiO₃, and has been called davemaoite. It is thought to be the third most abundant mineral in the lower mantle and is capable of holding various isotopes of uranium, thorium and potassium. And it is these isotopes which generate a lot of the heat in this part of the mantle.

The inclusions in the diamond must be at a very high pressure as the mineral cannot exist at surface pressures. You can make a mineral but you cannot name it as a mineral if it is not found as naturally occurring. Being tiny and in a diamond counts as naturally occurring!


This diamond holds tiny black specks of davemaoite, a mineral formed at high temperature and pressure in the deep Earth. Credit: Aaron Celestian, Natural History Museum of Los Angeles County

Wednesday, 10 November 2021

Explosive Lake Kivu - an audio long-read

Explosive Lake Kivu - an audio long-read 

Lake Kivu has 300 cubic kilometres of dissolved carbon monoxide 60 cubic kilometres of methane! 

You can listen very pleasantly to a long-read from Nature HERE and find out about the science, the business and the politics - nothing is ever easy!

Saturday, 6 November 2021

Planetesimals or Pebbles

Planetesimals or Pebbles 

How do planets form? For decades, when asked, people like me would mutter something about planetesimals and quickly move on. THIS ARTICLE suggests that the word I should mutter is pebbles. And tell people to read the article!

Apparently there was some difficulty about planetesimals - it would take too long for them to form. A planet like Jupiter would take tens of millions of years to form a core, by which time the protoplanetary disc from which they would need to accumulate gas would no longer exist. Instead of planetesimals, measured in 100's of kilometres, pebbles, measured in millimetres and centimetres, were the answer. And todays telescopes could see them.


  
ALMA observations of protoplanetary disk around HL Tauri in 2014 revealed hidden structures, including the presence of pebbles in the disk.

ALMA (ESO/NAOJ/NRAO)

The pebble theory rapidly gained acceptance for the giant planets but it has difficulties for smaller planets like the Earth. The article discusses this and comes to no definite conclusion. I suspect that debate will continue for years and, eventually a consensus will be reached. 

In the meantime the word is pebbles - probably!

Thursday, 4 November 2021

Down to Earth Extra - November 2021

 Down to Earth Extra - November 2021 


The latest edition of Down to Earth Extra is HERE.

And you can read it below.  


La Palma Videos

La Palma Videos 

A correspondent has told me that these three videos are well worth viewing, especially the first and the third. I quite agree!

Eruption Update




The Noisy Volcano



The Lava Delta


Saturday, 23 October 2021

Were Dinosaurs Good Neighbours?

Were Dinosaurs Good Neighbours? 

A correspondent has sent me THIS LINK - many thanks. In it Mike Benton discusses whether dinosaurs were social animals. The basis of his discussion is THIS PAPER. the researchers have found and described a site in Patagonia where they found nests with eggs and the skeletons of Mussaurus patagonicus. The skeletons ranged from babies to adults. The age is given as 193 million years.

The nests were spaced at a distance consistent with the animals size - close but not too close. It is suggested that they returned to the site regularly. There is evidence that it is a life assemblage - at least for the eggs - perhaps a dust storm buried the eggs. The skeletons are mostly complete and therefore are at the place they died.

So did these dinosaurs live in family groups? Mike Benton is beginning to think so - dinosaurs were warm-blooded, feathered, fast-moving and had sophisticated behaviour.


The research team studied fossils at an early Jurassic site in Patagonia, Argentina. Alejandro OTero

Thursday, 14 October 2021

Two Contrasting Landslides

Two Contrasting Landslides 

I came across these two articles on The Landslide Blog

THE FIRST is probably the slowest landslide measured - 2mm per year. It is big - a block of limestone 900m by 400m sliding over a layer of clays and marls. It is in Tunisia and it looks spectacular. Obviously a still photograph rather than a video.



THE SECOND is rather faster. It occurred in the Dolomites on the 9th October at the Punta dei Ross, Croda Marcora.


It becomes rather hectic at the 38 second mark. The measurements become m per sec rather than mm per year.

Both landslides are fascinating.