Lexical closures are an implementation technique in languages with first-class functions.
I'm interested in a simple operational description of function closures. Does anyone know of such a description?
Is chapter 29 of Bob Harper's book what you are looking for?
Closures form an important concept that I try to teach in my undergraduate Programming Languages class. You can find my lecture notes online.
The Handout 8 shows big step semantics using environments and closures. The Handout 9 shows my flavour of the SECD machine. (The latter didn't work all that well for teaching purposes because the students got lost in detail and didn't develop good intuitions. So I switched to big-step semantics.)
Neither of these is what you are asking for, but perhaps they could form a starting point?