Using ellipsis to indicate a pause in conversation

Wikipedia has a sentence in its article on ellipsis:

In reported speech, the ellipsis is sometimes used to represent an intentional silence, perhaps indicating irritation, dismay, shock or disgust. This usage is more common amongst younger, Internet-savvy generations.[citation needed]

I can find plenty of random internet articles making a similar statement, but is there an actual authoritative grammar source that says this is grammatically correct? Is it just something the "Internet-savvy generations" have invented?

Here is an example from a story:

She swallowed hard. "I'm afraid, Mark. Maybe if you might... talk to him?"

Here the ellipsis is indicating a verbal hesitation in the quote rather than the typical use of indicating an omission.

According to Grammar Girl, several style guides support the use of ellipses to indicate a pause (the relevant paragraph can be found under the header The E-mail Ellipsis).

She quotes from the Chicago Manual of Style that "Ellipsis points suggest faltering or fragmented speech accompanied by confusion, insecurity, distress, or uncertainty."

I would consider such style guides to be the kind of authoritative source you were looking for.

I'm far from convinced there's any justification for that Wikipedia claim about this usage being more common amongst younger, Internet-savvy generations, except in the sense that many young people today probably actually write more often than earlier generations anyway, because they "chat" using text on social network sites, and post on forums. So you could say every aspect of writing is more common among the younger generation. But so far as I know, it's always been a common device, so the supposed "Internet" connection is spurious.

As I write, I see Bjorn has just posted this same link to Grammar Girl, which cites CMOS if GG isn't authoritative enough for OP (I think she's fine in her own right, though I don't always endorse CMOS "recommendations").

It's worth noting that in general, CMOS is "prescriptive" - it's a style guide, which specifies a particular (hopefully consistent) set of guidelines. Grammar Girl is primarily "descriptive" of all different usages which do in fact occur, without necessarily promoting one over another.