I see a lot of Norway maple types of that size and larger dying around here. Usually the top stars dying back first, and the tree survives for years with the center being dead. We just call it "maple decline", which is a combination of factors that stress weaken the tree. I'm not sure if there is anything else more obvious going on there, but you can google maple decline on norway maples for more info.

nurseryman33...where are you located that you see this..........we are in toms river NJ....which is south jersey.....the soil its in is sandy with grass.....

I am near Madison WI. I have seen huge Norway maples in Eastern PA, but they never seem to get that big around here. But now that they are considered an invasive species, there has been a shift more towards Sugar maples and Red/Silver maple types and fewer Norways.

Have you been using weed killer on the lawn? Maybe last year?
Mike

yes ..but supposedly just for the weeds......we are always careful not to put on trees.....but its a thought...why do you ask......

I used grass clippings from a gardener on a row of azaleas in my nursery. I found out later the grass had been treated with Weed-B-Gone. It killed the azaleas. I no longer used his grass clippings.
Mike