Novel and unusual  U-Th-Pb isotope observations and insights:  Th-rich diagenetic calcite in Early Cretaceous hardground, Persian Gulf, and the potential U isotope signature of dust inhalation by Gulf War veterans

Date: 
Tuesday 17 March 2020 - 13:00
Location: 
Other venue (see below for details).
Other Venue: 
NOC Southampton - Node Room (064/03) (Waterfront Campus)
Speaker: 
Randy Parrish (University of Portsmouth)

Novel and unusual  U-Th-Pb isotope observations and insights:  Th-rich diagenetic calcite in Early Cretaceous hardground, Persian Gulf, and the potential U isotope signature of dust inhalation by Gulf War veterans

 

Those of us who make isotope measurements, particularly if one’s work and mojo depends upon it, are always finding new things to do:  new mass spectrometry tricks, making old machines work like new, and with topics outside our comfort zone, trying to address thesewith our kit. Sometimes a dataset collected for one reason (or no good reason) leads you somewhere else.   This talk is about several datasets I’ve collected that illustrate these notions.  First, some of you will know I’ve worked on Depleted Uranium and Gulf War Illness for years now; the U isotope measurements were challenging, but there is a final conclusion and the illness has nothing to do with DU; however, the 234U/238U measurements done out of curiosity may, surprisingly, be a proxy for historic dust inhalation during the conflict of 1991, and this could have health assessment implications.   Next, I will talk about U-Pb LA-ICP-MS carbonate dating, a rapidly growing field now applied to diagenesis, deformation, palaeo-anthropology and -climatology.  A sample of Cretaceous hard ground from the Persian Gulf has diagenetic calcite that is U-depleted but Th-enriched, allowing a high precision age to be measured by the 232Th-208Pb decay scheme that proves diagenesis shortly after deposition.  Why the mobility and enrichment of Th?? – I have no idea, but this shows the value of measuring isotopes you didn’t think you needed to measure in the first place.  If there is time, I will show why doing data reduction a bit differently can improve the accuracy and precision of ages in U-Pb carbonate dating; regrettably, the community is being slow to take up these improvements perhaps  because unlike many of us, results rather than process is the priority. This informal and perhaps eclectic talk might be of interest to those of you who quite like geological mass spectrometry and its evolution.

Seminar category: 
G3 Seminars
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