# Source of Dresser Formation 3.5 Ga dating

I've seen many papers and sites that give the dating of Australia's Dresser Formation as 3.5 Ga (variously 3.48 or 3.49 Ga), but I can't seem to find the source of this.

Where does the dating come from, and what is it based on?

Panorama Formation: Paleoarchean min age: 3427 MA Age method: isotopic, U/Pb-Pb/Pb ion probe

Dresser Formation: Min Age: Ma: 3477 Age method: inferred, overlying unit

McPhee Formation: Min Age: 3477 Age method: isotopic, U/Pb-Pb/Pb ion probe

• Thanks! Not sure how I didn't know about that database, really useful to know. Sep 19 '17 at 20:58
• So, it's from between 3477 Ma (min age at top) and 3481 Ma (max age at base)? Weird that I've seen quite a few people referring to it as being from 3490 Ma... I guess they're just mistaken? (Unless there was some older dating that still circulates, or some source isn't included in the database?) Sep 19 '17 at 21:01
• @BertieWheen I've seen several articles (e. g. Ueno et al 2008) giving a 3.49Ga dating and they quote Thorpe et al. 1992. Constraints to models for Archaean lead evolution from precise U–Pb geochronology from the Marble Bar region, Pilbara Craton, Western Australia. In Glover, J.E., Ho, S. (Eds.), The Archaean: Terrains, Processes and Metallogeny. Geology Department and University Extension, The University of Western Australia, Publication 22, pp. 395–408. Unfortunately I do not have access to this publication to check. Sep 20 '17 at 7:17
• @plannapus Good point. I can't get a copy of that conferences proceedings either, it seems it's not available at all online and you can only get it through some Australian libraries. I found another 1992 paper on dating the region by the same authors (U-Pb zircon geochronology of Archaean felsic units in the Marble Bar region, Pilbara Craton, Western Australia) but it doesn't mention Dresser (as far as I could tell by a quick skim - in a bit of a hurry) Sep 20 '17 at 8:54
• @BertieWheen In Van Kranendonk et al. 2008, one can at least read this brief summary of the Thorpe et al. 1992 dating: A Pb–Pb isochron age of 3490 Ma was obtained from galena in barite of the chert–barite unit at North Pole (Thorpe et al., 1992b). Sep 20 '17 at 9:10
• There is something wrong with the second link.
– Fred
Dec 3 '17 at 2:03
• Also, they are nothing more than links; not even titles. Link-only answers are not appreciated on SE sites. Can you include the essentials of that information in your answer here? Dec 3 '17 at 9:56