If the story is "literary" (however you define it), then it'd likely be classified
slipstream, I think.
http://en.wikipedia.org/wiki/Slipstream_%28genre%29
Slipstream is not a simple combination of literary and sci-fi, that would be called Literary Sci-fi. Experiemental Slipstream is more in style and how the words and thoughts are presented. And how those things make the reader feel. It tends to be perception-changing. Also tends to explore the non-real aspect of a story. As opposed to magical realism, which assumes magic is real and therefore nothing has to be mentioned of the possibility of unreal. Another indication that it may be slipstream is that the quality of the writing may be characterized by dissonance. It's often jaring. But not dissonant for the sake of disonance. The instance has to demand it in order to explain the mood of the piece or character.
I cannot tell whether you have a simple mixed genre piece (literary sci-fi, paranormal fantasy), or slipstream (experimental writing often combining literary, sci-fi, fantasy etc), without reading it. And even then, experimental literature and its rules comes from the writer. So, I can't determine the genre for another writer. I suggest you research the topic experimental literature if you think it may be experiemental.
Scroll down to See Also for links to the various experimental forms:
http://en.wikipedia.org/wiki/Experimental_literature
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Interstitial, btw, is a designation for experimental, not mixed genre. Though a simplified view of interstitial is mixed genre, that is not what it has become.
And then there is this from
http://en.wikipedia.org/wiki/Interstitial_art:
The interstitial arts movement (from above link).
In the mid-1990s,
Delia Sherman,
Ellen Kushner,
Terri Windling,
Heinz Insu Fenkl,
Midori Snyder,
Kelly Link,
Gavin Grant,
Gregory Frost,
Theodora Goss, Veronica Schanoes, Carolyn Dunn,Colson Whitehead, and other American writers interested in fantastic literature found themselves commiserating over the common perception that the genre-oriented
publishing industry found it difficult to market truly innovative fiction involving unusual, fantastical, or cross-genre elements—because the mainstream
literary fiction field demanded stories based in
realism, while the
fantasy field demanded stories that mostly followed the standard conventions of
sword and sorcery or
high fantasy. Yet it seemed to the authors that some of the best literature was that which didn't quite fit tidily into either category but instead was being discussed in terms of more amorphous, "in-between" descriptors such as "
magic realism," "
mythic fiction," or "the
New Weird." Further, the idea of interstitiality applied to other kinds of "in-between" fiction (unrelated to fantasy) and other "in-between" arts.
Over a period of several years, Kushner and Sherman prompted ongoing discussion about the importance of cultivating artistic "in-betweenness" led to the formulation of the broad concept of interstitial art. In 2002, literary scholar
Heinz Insu Fenkl founded ISIS: The Interstitial Studies Institute at the
State University of New York at New Paltz, and in 2003-04, Sherman & Kushner and some of their colleagues established the Interstitial Arts Foundation, a
501c(3) nonprofit organization dedicated to developing community and support for artists, arts-industry professionals and audiences whose creative pursuits are interstitial in nature.
