What were the chief reasons behind Europeans’ move to expand, explore, conquer, and colonize the Americas?

The main motive of European exploration and sea adventure was to find and establish new commercial routes with Asia, particularly with India and China. The Turkish possession of  old Constantinopole (which had fallen in Turkish hands in 1453) and the Bosphorus Strait had cut the traditional routes. So, the Europeans badly wanted to find new routes to import species and other items. The "discovery" (a polemic term) of America by Columbus was accidental, he did not know he´d found a new continent, he never set sail to a new continent conciously.

Explanation:

radioactive dating, also known as  radioisotope dating  is a process that in  estimating the approximate  age  of  rocks. these data can be analyzed from  the studies dealing with the  decay of the radioactive elements that are present in these rocks. in nature, there are a few types of materials or atoms which are quite unstable and they spontaneously decay or breakdown to form other kinds of atoms.