What were the major causes of european exploration

The majort cause of the European exploration was the search for spices.
Back then, spices such as chili and pepper was one of the most profitable commodity in European Trades.
The exploration was being done in order to find other spices resources that the merchant guilds could buy with cheaper price.

There are 2 kinds to what caused the European exploration. First, it was caused by technological transformation that made it even more possible. The changes that needed it were from the ship technology and navigational technology. 

Second, Europeans wanted to explore the world so that they could find people who aren't exposed to Christianity and bring the "true faith" to those people. But mostly because they wanted to get rich.