Well, the images leave unanswered questions (the unfamiliar nature) but also they generate strong interpretations of what they may represent. The disturbing factor derives not from the unfamiliar, but fromthe latter: the potential interpretations.
There are a class of 'psychic conflicts, suggested by these artstic representations' which most people are less familiar with, and for good reason. Beauty doesn't derive merely from the familiar either - something unfamiliar could potentially be beautiful. Something unfamiliar, also comforting and beautiful.
There is also the truth that analysis of a work of art as a representations of one person's experiences, may lead to the unfamiliar becoming understood. That often depends on the artist's willingness to reveal or conceal for whastever reason, those 'secrets'. As yet, the analysis is incomplete. To resteate, the reason for it being disturbing (which it is for me) goes a little beyond it being unfamiliar.
RE: Understanding the abstract