Complex sentence: Guarionex was captured during one of those confrontations and was sent to Spain in 1502, but the ship sank during a storm, along with a fortune in gold said by Bartolomé de las Casas to be worth 3600 castilians.
Split into simpler sentences: Guarionex was captured during one of those confrontations and was sent to Spain in 1502, but the ship sank during a storm. In addition to the loss of Guarionex was the loss of a fortune in gold said by Bartolomé de las Casas to be worth 3600 castilians.