EARTHTIME News
    




U-series Geochronologic Data has a new information page. And they are part of EarthCube.

Allan Rooney starts off the new Re-Os section with a brief introduction to the method

Sidney Hemming reports on inter-laboratory and inter-method comparison of the Fire Clay tonstein. See her report here.

Learn how to qualify for aliquots of EARTHTIME 205Pb-233U-235U and 202Pb-205Pb-233U-235U tracer solutions. See the U-Pb page.

This paper reports high precision analyses of common U standards which are a big improvement over existing results.

Here are examples of integrating high precision geochronology with astrochronology for the Carboniferous and the Cretaceous.



INTERESTING LINKS

Ar-Ar pipette blog

EARTHTIME Europe

U-Pb_Redux 2.7 and Tripoli 4.7



UPCOMING MEETINGS

Crowdsourcing the Next Generation of Isoplot: An AGU Town Hall. Tuesday, 16 December 2014, 12:30 PM - 1:30 PM, Moscone West, 2006



OTHER IMPORTANT STUFF

A new EARTHTIME tool is now available for recalculating Ar-Ar dates in light of new decay constants and fluence monitors. Check it out!!

K12 teachers will want to see our new educational module on radioactive decay and isotope dilution

Need a job?. See the jobs listing for details.

Synthetic U-Pb solutions for assessing ID-TIMS intra- and inter- laboratory reproducibility are now available.

Tripoli, a powerful new program for viewing, filtering, and interpreting cycle-by-cycle mass spectrometer data, is now available free of charge. For more information, click here.

Data Sucker is also here. Learn about it here.

Meeting Report: Here's a PDF summarizing the recent European EARTHTIME meeting.


Need a job? See our jobs board.

TOPSOIL is NOW AVAILABLE

    Topsoil is a desktop application and Java library that creates data visualizations for geochronologists and other earth scientists. The project is led and maintained by CIRDLES, an undergraduate research lab at the College of Charleston in Charleston, South Carolina.

The name "Topsoil" is an anagram of "Isoplot", the name of an enormously successful Microsoft Excel Add-In with similar capabilities that now works only in older versions of Excel.

If you are interested in learning more about Topsoil, please contact Jim Bowring.    

Topsoil at github    

Note that UPb_Redux is now ET_Redux and also available at github.


Tripoli is an open-source software package for Windows that is used to visualize and interact with mass spectrometer data, perform isobaric interference and fractionation corrections, and export the results to data reduction software like U-Pb_Redux. It is the first step in a beginning-to-end data review, reduction, and archiving workflow.

Tripoli makes it easy to visually locate and discard outliers or bad blocks of data with a mouse click. Saving your work records these choices for later reference. Tripoli will also apply isobaric interference and fractionation corrections--even letting you download EARTHTIME tracers from the internet--and keeps a record of which corrections have been applied and what values have been used (for instance, the 18O/16O for uranium oxide correction or tracer IC used for fractionation correction).

In LiveWorkflow mode, Tripoli will read mass spectrometer data is it comes off the instrument, giving you live access to your data. Any required corrections happen in real time, and exporting the data is as easy as clicking a button. Paired with the LiveWorkflow mode in U-Pb_Redux, you can see the relevant dates and their uncertainties evolve in real time. You can stop running samples as soon as you are convinced that they are not worth the time, or continue analyzing important samples until their uncertainties achieve the required precision. Running samples in LiveWorkflow also means that there is no data handling to do after the mass spectrometry: your work is done when the last analysis finishes.

Jim Bowring and CIRDLES (cirdles.org) work hard to make sure that Tripoli is compatible with all mass spectrometer files and formats. If Tripoli cannot read your data, contact Jim at [email protected] and your format will be added to the list.


U-Pb_Redux is an open-source, platform-independent software package that transforms measured data, lab parameters, and physical and decay constants into U-Pb dates, uncertainties, and visualizations, and archives the results. U-Pb_Redux provides the tools for the final half of a beginning-to-end U-Pb geochronology workflow.

Data reduction in U-Pb_Redux starts with raw mass spectrometer data, preferably exported from Tripoli. The raw data is then combined with the other required laboratory parameters, like the tracer and laboratory Pb blank IC, all of which can be changed from analysis to analysis and assigned uncertainties. The resulting dates, isotopic ratios, and other information are presented in publication-ready data tables, concordia plots, and weighted mean plots, and may be archived to the online database Geochron.org, which is associated with the larger EarthChem and IEDA framework. An important feature of U-Pb_Redux is the facility to take in, organize, and archive, and compile together legacy data sets.

What’s new:
Recent advances in U-Pb_Redux include using full, explicitly defined covariance/correlation matrices to describe the uncertainties in the isotopic composition of tracer, initial common Pb, and laboratory blank Pb isotopic compositions. For the tracer, this allows the user to capture all of the ways that uncertainties in the tracer isotope ratios relate to one another, which have been calculated during tracer calibration. Including these correlations reduces the estimated tracer contribution to a 206Pb/238U date from > 500 ppm to

U-Pb_Redux is also capable of rigorously propagating the systematic uncertainty contributions from the tracer, along with decay constant uncertainties, into weighted mean dates. You can combine data from multiple tracers, your lab’s or the EARTHTIME tracers ET535 and ET2535, and propagate the uncertainties that are different between the two, like their Pb ICs, without canceling out their common systematic uncertainty contributions, for instance from the 233U/235U and 235U/205Pb ratios.

What’s next:
CIRDLES and EARTHTIME are developing the next generation of these software packages that will extend the current capabilities in parallel to handle U-Pb dating using LAICP-MS from raw data to archived analyses. Currently, legacy data sets from other LAICP-MS data reduction programs can be imported, organized, and archived automatically. The full data reduction capabilities will be finished by March 2013 and demonstrated at an NSF-sponsored workshop in Charleston, SC March 6-8, 2013. For details on the workshop please contact Jim Bowring.


References:
Bowring, J. F., N. M. McLean, and S. A. Bowring (2011), Engineering cyber infrastructure for U-Pb geochronology: Tripoli and U-Pb_Redux, Geochem. Geophys. Geosyst., 12, Q0AA19, doi:10.1029/2010GC003479.

McLean, N. M., J. F. Bowring, and S. A. Bowring (2011), An algorithm for U-Pb isotope dilution data reduction and uncertainty propagation, Geochem. Geophys. Geosyst., 12, Q0AA18, doi:10.1029/2010GC003478.





EARTHTIME is supported by the National Science Foundation.