@Anthro @Ceedave The 4.3 Ga age is from coupled Nd-Sm systems (short and long lived); the mafic rocks do not have zircons. The younger age is from zircons in cross-cutting felsic units. This is the work of Jonathan O'Neil (now at #uottawa) https://mcgillnews.mcgill.ca/s/1762/news/interior.aspx?sid=1762&gid=2&pgid=1190

https://en.wikipedia.org/wiki/Nuvvuagittuq_Greenstone_Belt

Some of the rind remains and is compositionally distinct. Recent work has used triple oxygen to constrain seawater chemistry (https://www.sciencedirect.com/science/article/abs/pii/S0012821X22001753)
#Hadean #McGilUniversity #PillowBasalt

@allochthonous @silicatefondue @geo_garver

Fabulous #pillowBasalt image, and I’m happy to have visited your website. Please keep the cross cutting relationship animation up, I’ll refer my #EarthScience class at #UMassBoston to it. Super!

Compare the Nuvvuagittuq Greenstone Belt pillows with those from the 3.5 billion hear old Barberton Greenstone Belt, South Africa, visited by @allochthonous

https://all-geo.org/highlyallochthonous/2007/07/what-is-a-greenstone-belt/

or the pillows of https://fosstodon.org/@geo_garver@mastodon.social from the 57 Ma Resurrection Peninsula Ophiolite, Alaska.
https://fosstodon.org/@geo_garver@mastodon.social/109540738352007159 #PillowBasalt 2/2

The pillow rinds have preferentially weathered, outlining the basalt pillows formed at least 3.75 and perhaps as long ago as 4.3 billion years ago. Now metamorphosed to amphibolite grade. In the Ujaraaluk unit of the Nuvvuagittuq Greenstone Belt, near #Inukjuak, northern #Quebec. #McGill University #EarthSystemScience #PillowBasalt #Hadean 1/2

Pillow basalts of the 57 Ma Resurrection Peninsula Ophiolite, Alaska.

These are some of the most spectacular pillows I've seen.
These represent eruption of basaltic magma to the ocean floor, and they are directly related to the sheeted dike complex recently posted.

The Stellar sea lions have hauled out on a detached block with exposed flow tops.

#Alaska #Ophiolite #PillowBasalt #Paleocene #Chugach