May a large asteroid impact in the Pacific have triggered a cascade of tectonomagmatic events leading to formation of the Mid-Cretaceous Chilean Iron Belt?

Résumé

A cascade of tectonic and magmatic events that took place in the Pacific and northern Chile during Mid- Cretaceous led to formation of one of the World’s largest Kiruna-type iron belts with reserves of ~2000 Mt (60% Fe). Geological evidence indicates that a major change occurred in MidCretaceous time, when superplume emplacement and plate reorganization processes took place in the Pacific. Although this scenario is well documented, no proposals have been put forward on the actual event that may have triggered the subsequent cascade effect. In this regard, a large meteoritic impact in the Pacific may have initiated massive volcanism leading to formation of the Ontong-Java Plateau. Such an impact may have been the geologic equivalent to the falling domino principle: once the first piece is knocked over, the rest fall quickly. Thus, once the meteorite impacted the Mid-Pacific, subsequent and sequential plume emplacement, massive volcanism, plate reorganization, increased plate stress along the Pacific margin, fault zone formation and emplacement of the Chilean Iron Belt would have taken place within a relatively short time span in Mid-Cretaceous time.