Mesozoic Rocks in the Northernmost Portion of Colombia: Implications for Caribbean Geodynamic Evolution

The Mesozoic rocks of the Alta Guajira region of Colombia record several events since the Triassic that may lead to understand the evolution of the Caribbean plate. These rocks are located south of an interpreted paleosuture (the Simarua Fault), that separates autoctonous (south) from aloctonous (north) provinces. During Late Triassic – Early Jurassic times, explosive volcanic activity is recorded in rhyodacites and associated volcanosedimentary rocks. This activity is followed by contemporaneous emplacement of intrusive igneous rocks and sediment accumulation in a passive margin during the middle of the Jurassic. Finally, a new explosive volcanism event affected the accumulation of Late Jurassic – Early Cretaceous rocks.

The mentioned rock record is interpreted as evidence of the extensive tectonic regime that prevailed during the separation of North America and South America. Initially, the beginning of the formation of a NE-SW continental rift basin was marked by explosive volcanic activity. The ongoing separation of the two continental masses during the Middle Jurassic produced a block-faulted terrane, with two main depressions separated by a paleohigh, where a thick pile of clastic sediments were accumulated with little influence of volcanic activity. A second explosive volcanic event started in Late Jurassic; this event lasted until the Early Cretaceous and occurred simultaneously with an increase in vertical movement of tectonic blocks.