So you're saying Colosseum's REE's 'flowed' south down to MP? Maybe there's nothing left?
Did you know the MP REE deposit formed 1.4 billion years ago? I reckon the landscape back then looked nothing like it does today. What was high ground way back then might well be low ground today and vice versa. Orogenic uplift, basin subsidence, and erosion events over 1.4 billion years of geologic history. 1.4 billion years! This is more than a billion years before the dinosaurs. Just oceans of single cell organisms back then. Pond scum, essentially...