Sir David Attenborough visits the lab



On Tuesday April 17, we had the great pleasure of giving a lab tour to Sir David Attenborough, who was the guest of honour at the Kathleen Lonsdale Building reopening ceremony. After a brief introduction to U-Pb, U-Th-He and K-Ar geochronology, our esteemed guest asked the pertinent question as to whether these chronometers could be cross-calibrated. Interestingly, improving such cross calibrations turns out to be one of our top priorities for the coming years!

Further information about Sir David's visit to the Department can be found here.

IsoplotR released to the world



IsoplotR is a free and open-source substitute for Kenneth Ludwig's popular Isoplot add-in to Microsoft Excel. The program is written in R and includes functions for U-Pb, Pb-Pb, 40Ar/39Ar, Rb-Sr, Sm-Nd, Lu-Hf, Re-Os, U-Th-He, fission track and U-series disequilibrium dating. IsoplotR can be run in three different modes: online, offline and from the command line. Its underlying principles are described in a paper that has been accepted for publication in:


Vermeesch, P., 2018, IsoplotR: a free and open toolbox for geochronology. Geoscience Frontiers, doi: 10.1016/j.gsf.2018.04.001.

Geologists discover 60 million-year-old meteorite impact

 

The LGC were part of a team of geologists who discovered the first recorded occurrence of vanadium-rich osbornite on Earth, from two sites on Skye, northwest Scotland, which are interpreted as part of a meteoritic ejecta layer. Vanadium-rich osbornite has only previously been reported in space dust from NASA missions, but on Skye it has been identified as an unmelted phase.


Drake, S.M., Beard, A.D., Jones, A.P., Brown, D.J., Fortes, D., Millar, I.A., Carter, A., Baca, J. B., Downes, H. (2017) Discovery of a meteoritic ejecta layer containing unmelted impactor fragments at the base of Paleocene lavas, Isle of Skye, Scotland. Geology, https://doi.org/10.1130/G39452.1


High throughput geochronology by automated phase mapping and LAICPMS

The first step in most geochronological studies is to extract dateable minerals from the host rock, which is time consuming, removes textural context, and increases the chance for sample cross-contamination. A collaborative research effort between the LGC and Rocktype Ltd. has developed a new method to rapidly perform in-situ analyses by coupling a fast Scanning Electron Microscope (SEM) with Energy Dispersive X-ray Spectrometer (EDS) to a Laser Ablation Inductively Coupled Plasma Mass Spectrometer (LAICPMS) instrument.

Vermeesch, P., Rittner, M., Petrou, E., Omma, J., Mattinson, C. and Garzanti, E., 2017, High throughput petrochronology and sedimentary provenance analysis by automated phase mapping and LAICPMS, Geochemistry, Geophysics, Geosystems (doi: 10.1002/2017GC007109)

Widespread Antarctic glaciation during the Late Eocene

A provenance study of late Eocene marine sedimentary rocks drilled on the southeastern margin of the South Orkney microcontinent in Antarctica (Ocean Drilling Program Leg 113 Site 696) provides the first evidence for a continuity of widespread glacier calving along the coastline of the southern Weddell Sea embayment at least 2.5million yrs before the prominent oxygen isotope event at 34–33.5 Ma that is considered to mark the onset of widespread glaciation of the Antarctic continent.