I am no expert, but I can't cite any. I'm glad Fr. Matt answered in the meantime.
And it might be more fair to say that I lean toward OEC and see nothing in Scripture or dogma that absolutely necessitates YEC. But if YEC turned out to be true (I'm guessing we will find out in the end) then I can just as easily accept that, though if it is a strictly literal 6-day creation of all matter, that would surprise me.
But what I have found when reading on my own (not anything cited as supporting evolution or creation) - the Fathers speak a great deal and in great depth on many nuances regarding creation. But what they concern themselves with isn't the same things we often concern ourselves with.
I wonder sometimes if this debate has not been greatly sharpened by current scientific theory and fundamentalist Protestants. The
idea of species arising from one another (i.e. evolution) was not new with Darwin. The ancients had different forms of it. And it was mentioned here and there in the texts by the Fathers that I've seen. (Spoken against it that I've seen.) But they don't go on for pages about it as we tend to do. Rather they talk about how man relates to God, how man relates to animals, man's role in the created order, how God is understood in Trinity and many other things - in very great detail.
So ... I may be wrong, but that's part of why I'm more reticent to focus too much on this debate. I fear maybe we've been affected too much by heterodox ways of thinking.
God created. We need that. And we need to understand truth in the story of Adam and Eve and the fall, and in the Resurrection. It's hard to assert that truth if you have no literal form of Adam whatsoever. So I think we need that too.
The rest ... I don't know. The Fathers didn't seem to entangle themselves much in that particular debate, but yet focused very minutely on other points we can learn from the Genesis accounts. So maybe we can learn from them what are the important lessons for us as well. Or maybe it just wasn't so widely asserted.
But what I do find is that there is so much depth and richness that the Fathers
do pull out of Genesis. And it's edifying. And when I start reading them, that's where my attention goes. And it's so much more important that the details we can't know of exactly
how God created. And we have the SURE guide of the Saints, rather than our own imaginations steeped in current scientific theory and heterodox teachings.