Genesis 6 and 1 Enoch

"Angels who didn't keep their first domain, but deserted their own dwelling place, he has kept in everlasting bonds under darkness for the judgment of the great day" (Jude 1:6). Jude does not pause to explain who these angels were or argue for their existence — he simply assumes his readers already know, treating the rebellion as settled, established background rather than a novel claim needing defense.
That assumption matters for the question of dependence. The core supernatural reading of Genesis 6:1-4 does not rest on any non-canonical book — though later Jewish literature, especially the Book of Watchers within 1 Enoch and the book of Jubilees, does develop the story with far more narrative detail than Genesis itself ever supplies. What the New Testament does is presuppose the wider tradition without needing to reconstruct it from scratch. Jude 6 and 14-15 — the latter quoting a line from that same Enochic tradition directly — treats angelic rebellion as common knowledge among its first readers. Second Peter 2:4 confirms it independently: "if God didn't spare angels when they sinned, but cast them down to Tartarus, and committed them to pits of darkness, to be reserved for judgment." And 1 Peter 3:18-22 carries the same storyline further, describing Christ, after his resurrection, making proclamation to the imprisoned spirits who were disobedient "in the days of Noah" — continuing the very flood-imprisonment-judgment arc Genesis 6 first opens.
The canonical text itself, read closely alongside these New Testament allusions, is sufficient to support the basic outline, even where the fuller narrative color comes from elsewhere. Judgment for that ancient rebellion is not left uncertain, only unfinished — held, as Jude says, "for the judgment of the great day."