Lmst

SciTech Chronicles. . . . . .May 17th, 2025

#volcanoes #Io #collision #gravitational #AMOC #dilution #mass #expansion #sediment #cooling #ice-sheet #AMOC #Negev #pendants #child #"Tel Malḥata" #SAR #Magellan #metamorphism #subduction

#DogWalkingGeology a superb example of a retrogressive reaction front from this morning's walk with Spud at Uisken. To the top+right is garnet amphibolite preserving clean high temperature (about 650-700 oC) metamorphic minerals. The paler green grey rock at bottom+left has formed by later hydration of the amphibolilte at 350-400 oC. The boundary between fresh high grade rock + completely altered low-grade rock is sharp over a distance of a few cm. #Geology #Metamorphism #Retrogression #Mull

About 40cm height of a clean rock face in contact with coarse shelly/pebbly sand on a beach. The rock is pale greenish grey to the bottom and left, and black, pink and white to the top and right, with the boundary sloping from top left to bottom right.

#MinCup24 Vote #kyanite

Here's some more kyanite from this morning's wee walk near Uisken in Mull. Nice blue kyanite blades up to 3cm+, with some red stonecrop and lichen keeping them company.

#Geology #Mull #Moine #Metamorphism

A close-up view of a rock surface, with peay, lichen and a little plant with fat red leaves on the right of the eimage. From the bottom centre to centre-right, several blue-grey elongate crystals can be seen.

#MinCup24 kyanite vs rhodochrosite

Vote #kyanite! The glorious blue harbinger of metamorphism done right: high pressure, and aluminous chemisty = beauty + lots of geo-information 🤩 🥰 🤓

Here's some Mull kyanite, together with it's pink cousin andalusite, in an outcrop at Ardalanish in Mull - what a rock! 😊 😍

#Geology #Mineralogy #Metamorphism #Mull #Moine @MineralCup

A close-up picture of a weathered rock surface. There are some fronds of grass etc at the bottom, and some grey lichen towards the top, but the clean rock shows a band of sky-blue and pink crystals. An orange propelling pencil at the left provides scale.

@barrygoldman1 They're not all preserved in the same rock! The last metamorphic event recorded in this sample annealed out all the growth zoning in the major rock-forming minerals.

Some of the evidence is preserved in the younger tonalites that contain more resistant minerals like zircon...
#geology #metamorphism

#Zircon doesn't just keep time; it can record temperature too. The image is of a ~4mm zoned zircon crystal from the Bancroft-area of Ontario (Grenville-age granulite metamorphics). The trenches are 40 and 60 microns wide, created by laser-ablation #ICPMS analyses.

~3.5 parts per million titanium corresponds to crystallization temperatures of ~ 675°C (plus or minus a lot, unfortunately, in this case).
#MinCup23 #metamorphism

A backscattered electron image of a zircon crystal with multiple zones. The change in brightness of the zones are caused by variations in trace elements such as hafnium, titanium, and uranium. Two laser ablation trenches are present in the upper right corner, where material was sampled for analysis.

More #JoysOfSpring in Mull 😊 . One of my favourite wee corners near Uisken, with wonderful ourcrops of "Moine" metamorphic rocks on tiny beach of perfect shell sand. See alt text for geological details... Garnets are visible in this image! #Mull #Geology #Metamorphism #GarnetAmphibolite

Gnarly outcrops of grey and black rocks surround a beach of white sand, under a blue sky. The rocks in the left foreground show banding of paler and darker grey and are metamorphosed sedimentary rocks. The darker rocks to the right, and in the centre background are garnet amphibolite, originally a basaltic sill or dyke cutting the sedimtnary rocks, before they were all metamorphosed. In the dark amphibolite near the contact with the banded grey rock, pinkish spots of garnet can be seen: they are much bigger near the contact than inside the amphibolite. This metamorphism probably occurred around 450 million years ago.

#Wavellite

Interesting facts:

• forms as a groundwater precipitate in aluminous or ferruginous #sedimentary #rocks, a product of low-grade #metamorphism of such rocks or in hydrothermal veins.

• #crystal that forms in radiating circles. This mineral is easily recognized by its radiating clusters of #crystals forming circles.

#geology #geo

#NewPaper #Paleontology #Metamorphism

Aodhán Ó Gogáin, Gary O'Sullivan, Thomas Clements, Brendan C. Hoare, John Murray & Patrick N. Wyse Jackson (2022)
Metamorphism as the cause of bone alteration in the Jarrow assemblage (Langsettian, Pennsylvanian) of Ireland
Palaeontology 65(6): e12628
doi: https://doi.org/10.1111/pala.12628
https://onlinelibrary.wiley.com/doi/full/10.1111/pala.12628

Boudinage

Boudinage are one of the most spectacular geologic structures and some of my favorite rocks. The boudins are the eye-shaped lenses of rock wedged between the white quartz layers. Find out how they formed below.

Callan Bentley's great AGU blog post on boudinage explains it all: https://blogs.agu.org/mountainbeltway/2011/06/20/boudinage-favorite-geoword/

More beautiful boudinage here: https://goo.gl/XXSyEv

Image from: https://folk.uib.no/nglhe/PhotoAlbum/Boudinage%20Chapter%2014/index.html

#boudinage #metamorphism #rocks #geology #MetamorphicMonday #ScienceMastodon