Guessing this is a Shamrock spider.
I think it is a marbled orb-weaver. See how the first half of the legs are colored like the head?
That’s an interesting way to identify Araneus marmoreus. I agree with your identification. This is a tricky spider. I’m going by the way the legs go from red and black to white and black. The dorsal thin line markings like marbling aren’t seen on any other American orbweavers that I can think of.