Please explain Zircon and rutile U-Pb geochronology of the Niquelandia layered mafic and ultramafic intrusion?

Question

this question was on my homework, and I'm only in 10th grade! I can't believe they expect us to know these things! I wish I didn't go to boarding school :(

Answer 1

You can find an abstract of an article written on this subject at the url below. The title and volume listed below.

In a nutshell, the dates on this huge mafic-ultramafic complex in Brazil (old ocean floor possibly) point to two big events in the earth's early tectonic history: First, a Mesoproterozoic extension event (like a spreading ridge) that forms the mafic-ultramafic complex (ocean crust and seafloor)(1583±25 Ma , 1565±22 Ma-million years ago). Then, a continental collision event: younger dates of 770–795 Ma (million years ago) for metamorphism of the complex (" high-grade amphibolite to granulite facies prograde metamorphism"), may represent the timing of a continental collision event.

Zircon and rutile U---Pb geochronology of the Niquelândia layered mafic and ultramafic intrusion, Brazil: constraints for the timing of magmatism and high grade metamorphism

by Ferreira-Filho and several others.
Precambrian Research
Volume 68, Issues 3-4 , August 1994, Pages 241-255