@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

Compare the Nuvvuagittuq Greenstone Belt pillows with those from the 3.5 billion year 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 @geo_garver from the 57 Ma Resurrection Peninsula Ophiolite, Alaska.
https://fosstodon.org/@geo_garver@mastodon.social/109540738352007159 #PillowBasalt 2/2

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