#ThinSectionThursday Fabulous πͺΆ featheryπͺΆ symplectite textures in this Lewisian gneiss from the south slopes of Roneval, South Harris. Pink garnet & green clinopyroxene formed during early, hot, high pressure granulite facies metamorphism have reacted during later decompression/hydration to produce zones of finely intergrown amphibole, plagioclase, and opaque magnetite. View ca 2mm across. Tasty! π π₯°
SciTech Chronicles. . . . . .May 17th, 2025
#volcanoes #Io #collision #gravitational #AMOC #dilution #mass #expansion #sediment #cooling #ice-sheet #AMOC #Negev #pendants #child #"Tel MalαΈ₯ata" #SAR #Magellan #metamorphism #subduction
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.
#MinCup24 kyanite vs rhodochrosite
Vote #kyanite! The glorious blue harbinger of metamorphism done right: high pressure, and aluminous chemisty = beauty + lots of geo-information π€© π₯° π€
Here's some Mull kyanite, together with it's pink cousin andalusite, in an outcrop at Ardalanish in Mull - what a rock! π π
@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 ~ 675Β°C (plus or minus a lot, unfortunately, in this case).
#MinCup23 #metamorphism
Interesting facts:
β’ forms as a groundwater precipitate in aluminous or ferruginous #sedimentary #rocks, a product of low-grade #metamorphism of such rocks or in hydrothermal veins.
β’ #crystal that forms in radiating circles. This mineral is easily recognized by its radiating clusters of #crystals forming circles.
#NewPaper #Paleontology #Metamorphism
AodhΓ‘n Γ GogΓ‘in, 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
John Faithfull ππͺπΊπ΄σ §σ ’σ ³σ £σ ΄σ Ώπ§‘βπ»βπΏ
John Vaccaro (johniac)
Bill Minarik
John FaithfullππͺπΊπ΄σ §σ ’σ ³σ £σ ΄σ Ώπ§‘ βπΌβπΏ
attresa.geo
Thomas Holtz