Speed dating with ion specificity: in situ Rb-Sr ages using novel mass-spectrometry
Lead Research Organisation:
University of Bristol
Department Name: Earth Sciences
Abstract
An ideal geochronological technique should be able to produce a date from a single, easy analysis. Although in situ dating of zircons has come close to this goal, it is limited to this accessory phase, which typically needs to be separated from larger volumes of sample. Even more appealing would be the ability to date samples from a petrographic section, preferably on major mineral phases. This possibility exists for some high Rb-Sr phases using the 87Rb- 86Sr system, but this currently requires time consuming micro-drilling, separation chemistry and subsequent analysis. The problem with the 87Rb- 87Sr pair, and other beta decay systems commonly used in geological dating, is that the parent inevitably forms an isobaric interference with the daughter, such that phases with high parent daughter ratios, which have the potential to give the most precise dates, have the most interfered isotope ratios. These elemental inferences cannot be resolved by even the largest geometry mass spectrometers. A novel approach is to use a collision cell to achieve chemical specificity rather than mass resolution. Ion-gas reactions in the collision cell can reduce isobaric interferences by many orders of magnitude. Such a scheme exists for the Rb-Sr system and we wish to explore the potential of this approach with our unique collision cell, plasma multi-collector mass-spectrometer (Proteus). The student will work in both refining the reaction schemes to remove Rb from Sr (in collaboration with our CASE partner, Thermo Fisher Scientific), and harnessing these results to develop protocols on Proteus to measure isotope ratios from laser ablated material. The resulting methodology will be applied to the dating of inclusions in ultra-deep diamonds, the ages of which are a source of long standing debate. Laser ablation is an efficient means to sample these valuable samples of the deep mantle and the prospect of coupling this with isotopic analysis is a valuable goal.
People |
ORCID iD |
Timothy Elliott (Primary Supervisor) | |
Daniel Bevan (Student) |
Studentship Projects
Project Reference | Relationship | Related To | Start | End | Student Name |
---|---|---|---|---|---|
NE/P010342/1 | 30/09/2017 | 29/09/2021 | |||
1942747 | Studentship | NE/P010342/1 | 30/09/2017 | 29/09/2021 | Daniel Bevan |
Description | The work funded through this award has provided a significant progression in the ability to radiometrically date geological materials. Previously dating geological samples using Rb-Sr dating was an extremely time consuming technique taking several weeks to analyse only a relatively small number of samples. The development of the in situ Rb-Sr method with novel mass spectrometry now means samples can be rapidly dated directly from cut rock sections and cores. The ability to do this is particularly attractive for mining companies who could wish to rapidly construct a chronological framework of enormous mineral deposits. |
Exploitation Route | The use of this method as stated above can be used in a huge variety geological applications, such as the dating of microscopic inclusions in diamonds, or the construction of geochronological frameworks for ore deposits such as porphyry copper deposits which are going to be crucial for the transition away from fossil fuels. |
Sectors | Electronics Energy |
Description | Student Research Grant Program |
Amount | $2,800 (USD) |
Organisation | Society of Economic Geologists (SEG) |
Sector | Charity/Non Profit |
Country | United States |
Start | 06/2019 |
End | 04/2020 |
Title | In situ Rb-Sr Dating |
Description | The research conducted at the University of Bristol and Thermo Fisher Scientific has resulted in the development of a method for the in situ Rb-Sr dating of geological samples using collision (multi collector inductively coupled plasma mass spectrometry) MC-ICPMS technology. This powerful new geochronological tool allows extremely rapid dating of geological materials with spatial resolution of micro sampling provided by coupling with laser ablation technology. |
Type Of Material | Technology assay or reagent |
Year Produced | 2019 |
Provided To Others? | No |
Impact | The use of this dating method now provides the means to rapidly investigate many areas of ongoing research in geochemistry. These include constructing chronological frameworks of porphyry copper deposits, the dating of inclusions in 'super deep' diamonds and the detrital dating of feldspars to investigate the evolution of the Earth's crust. |
Description | CASE partnership with Thermo Fisher Scientific |
Organisation | Thermo Fisher Scientific |
Country | United States |
Sector | Private |
PI Contribution | The research conducted in to developing a method for in situ Rb-Sr dating by myself at the University of Bristol and during the 3 months of work conducted at Thermo Scientific in Bremen Germany, has provided important information for the development of collision cell MC-ICPMS technology (multi collector inductively coupled plasma mass spectrometry). |
Collaborator Contribution | Thermo Fisher have paid for any travel and accommodation for research placements in Bremen, Germany. They also provided the cost free use of two collision cell mass spectrometers for research during the placements. |
Impact | Due to the nature of the research involved in this project a non disclosure agreement requires me not to disclose any information involving this. |
Start Year | 2017 |
Description | Bristol Access |
Form Of Engagement Activity | Participation in an open day or visit at my research institution |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Schools |
Results and Impact | The purpose of the visit was to show a group of local school children a real research environment and lab. This involved them participating in a lab demonstration to look at trace element concentration in hair. |
Year(s) Of Engagement Activity | 2018,2019 |