There is a treasure story that could fit the date.
The treasure is supposed to be buried on this island. The island lies in the Atlantic Ocean many hundreds of miles from any civilization.
I made an expedition there in 1982. I had some PI metal detectors, but the ground was full of Basalt rocks that set the detector off.
So this is a metal detector story too.
For the treasure hunting story, I think it is better to post it on
THunting.com
Tinkerer