This may be disappointing comment to some descendants of Elizabeth Black (of which my wife is one), but Gantanaga or GantaƱaga appears in Family Search church records for Uruguay and Peru. And I found the name mentioned in some administrative records for Bilbao, Spain. My wife has zero native DNA, but her father has a small sample from Iberian. I have considered the possibility that Elizabeth was descended from Spanish explorers or pirates that may have had an early incursion off the North American coast. There's not a lot of information, for sure.