I really don't think that I would say there is such thing as a typically Oatesean sentence, in the sense that Joyce Carol Oates has a particular or signature style, except that she is exceptionally good at setting her writing in the unique feel of the novel or story she is writing. In that sense she is very economical in her writing; that is, it is all presented intentionally in a certain way, in order to help in the construction of the world of the story. In the case of Bellefleur, the opening paragraph struck me as oddly Proustian. For it is a single sentence, and reminded me of many passages in Proust's great work, which perhaps coincidentally or perhaps not coincidentally also delves in many ways into the theme of time, and the sequence of time. (The Bellefleur family, by the way, is also French.) The construction of long sentences, like the use of long words, can be clumsy, pretentious, poorly executed, or just inappropriate for the context. (Proust himself could write very short sentences just as effectively as the long ones.) In this case, it comes across beautifully, and begs the question (in my mind anyway) as to what this sentence might be telling us about the whole sage that is about to unfold.
It was many years ago in that dark, chaotic, unfathomable pool of time before Germaine's birth (nearly twelve months before her birth), on a night in late September stirred by innumerable frenzied winds, like spirits contending with one another-now plaintively, now angrily, now with a subtle cellolike delicacy capable of making the flesh rise on one's arms and neck-a night so sulfurous, so restless, so swollen with inarticulate longing that Leah and Gideon Bellefleur in their enormous bed quarreled once again, brought to tears because their love was too ravenous to be contained by their mere mortal bodies; and their groping, careless, anguished words were like strips of raw silk rubbed violently together (for each was convinced that the other did not, could not, be equal to his love-Leah doubted that any man was capable of a love so profound it could be silent, like a forest pond; Gideon doubted that any woman was capable of comprehending the nature of a man's passion, which might tear through him, rendering him broken and exhausted, as vulnerable as a small child): it was on this tumultuous rain-lashed night that Mahalaleel came to Bellefleur Manor on the western shore of the great Lake Noir, where he was to stay for nearly five years.