一派 here is a measure-word phrase meaning 'a whole stream / a wash of' — the same construction gives 一派胡言 ('a pack of nonsense'), 一派祥和 ('an atmosphere of peace'). 一派 + abstract noun is very productive.
register
Strong condemnatory tone — used to flatly reject someone's account as fabrication. Common in courtroom speech, polemics, and news commentary.
