The Precambrian in Southwest region, Mexico

Paleontology and geology

In the Southwestern Region of Mexico, Precambrian rocks form a basement under younger rocks and outcrop in a few places in the east. These metamorphic and igneous rocks date back to 1.0 Ga, recording the presence of volcanic islands, mountain ranges, and ocean deposits. They formed along the northern margin of ancient South America (then part of the continent of Gondwana), well south of, and across an ocean from, ancient North America (Laurentia). Later movements of tectonic plates would bring these Precambrian rocks to their present location. Sediments eroded from Precambrian rocks have been found in younger rocks in the south, suggesting that Precambrian basement rocks may be more widespread. Geologists continue to study how, when, and from where these sediments were incorporated.