I have here a link to a 2002 paper explaining the answer to your question. However you my need to log in to view that paper.
http://science.sciencemag.org/content/296/5574/1846
This is but 1 and there are numerous other papers out there explaining this region and also, very importantly, there are papers explaining radiometric dating methods, their pros and cons and when and where they should be used. If you aren't subscribed to any of these sites then this information is easily accessed through various educational sites as well as from books you can buy...
One of the reasons people like COFTY get annoyed with some posters is their tone of message. In your case you ask a question in a rather snarky way when the information you need is only a few clicks away on the internet. I have studied geology at the undergraduate level and when I think about the amount of information I have had to not only read but to also understand offhand comments like "...but some of this elevated intellectual thinking from scientists, in my opinion is pure ego..." really grates.