http://fortranwiki.org/fortran/show/Keywords says that in F77 (and therefore F90) the keyword is `block data`, two words, which neither Geany nor Scintilla will handle, but in F2008 `block` by itself is a keyword.
Geany does not distinguish versions of Fortran (or any language) and so the keyword lists are usually a combination up to the latest version.
As @b4n says, you would need to make yourself a custom version of the filetype file.