But much of both these areas have also been underwater in the last 80 million years. One only needs to travel around the South Island of New Zealand or New Caledonia to realize that much of the “landscape” is now uplifted “submarine” rocks.
Then there is the cool issue that places like Lord Howe Rise (now almost entirely underwater) have features that look like they were formed by subaerial exposure in the Eocene. The history of Zealandia, and particularly when it went “up and down” is very much a primary goal of the drilling in Expedition 371.