@article{Thern2020,
title = {Tourmaline 40Ar/39Ar geochronology and thermochronology: Example from Hadean-zircon-bearing siliciclastic metasedimentary rocks from the Yilgarn Craton},
author = {E.R. Thern, E. Blereau, F. Jourdan, D.R. Nelson},
url = {http://www.geochron.com.au/wp-content/uploads/2020/04/140.-Thern-et-al-2020-1.pdf},
doi = {https://doi.org/10.1016/j.gca.2020.03.008},
year = {2020},
date = {2020-04-13},
journal = {Geochimica et Cosmochimica Acta},
volume = {277},
pages = {285-299},
abstract = {We present 40Ar/39Ar ages and boron isotopes of tourmalines from a quartz-tourmaline intrusion cross-cutting the Hadean detrital-zircon-bearing metasedimentary rocks from the Mt. Alfred and Brooking Hills localities of the Illaara Greenstone Belt, Western Australia. Concordant 40Ar/39Ar plateau ages on the tourmalines at Mt. Alfred give a weighted mean age of 2935 ± 9 Ma (2sigma). These results are the first reported Archean 40Ar/39Ar ages directly obtained on tourmaline, and provide a minimum depositional age for this sequence, placing constraints on the depositional timing of detrital Hadean zircons to between 2935 ± 9 Ma and c.a. 3250 Ma (youngest detrital zircon age in sequence). This is the last known occurrence of abun- dant detrital Hadean zircons having been directly deposited in a sedimentary sequence, and thus suggests that most Hadean zircon sources have been exhausted by this time. The 2935 ± 9 Ma tourmalines occur within a quartz-tourmaline intrusion with associated stratiform layers and veins, inferred to have grown during a hydrothermal fluid circulation event. A younger generation of tourmalines from the Brooking Hills, 30 km south of Mt. Alfred yielded concordant 40Ar/39Ar plateau ages with a weighted mean age of 2624 ± 16 Ma. These tourmalines occur within and along the margins of post-kinematic quartz veins, parallel to the foliation fabric and marks the end stage of high temperature tectono-thermal events within the Illaara Green- stone Belt. The retention of 2935 ± 9 Ma tourmaline ages within the Illaara Greenstone Belt shows that the K/Ar system of tourmaline remained closed throughout repeated upper-greenschist metamorphic events ($450 C) between the ages of c.a. 2930 to 2630 Ma in contrast to muscovite recording plateau ages of about 2600 Ma. This is in agreement with an approximate Ar closure temperature between $534 and 628 C experimentally determined in this study.},
keywords = {Geochronology},
pubstate = {published},
tppubtype = {article}
}

@article{nelson_geochemical_2014,
title = {Geochemical and ion-microprobe constraints on the Archaean evolution of Singhbhum Craton, eastern India.},
author = {D.R. Nelson and H.N. Bhattacharya and E.R. Thern and W. Altermann},
url = {http://www.geochron.com.au/wp-content/uploads/2016/11/191.-Nelson-et-al-2014.pdf},
year = {2014},
date = {2014-01-01},
journal = {Precambrian Research},
volume = {255},
pages = {412--432},
abstract = {Geochemical and SHRIMP U-Pb zircon analyses were obtained for nine samples of the Singhbhum Craton to investigate major regional granite intrusion, volcanism, sedimentary deposition, metamorphism and deformation episodes. Detrital zircons within a recrystallized sandstone enclave within tonalitic gneiss provided a maximum time for deposition of 3375. ±. 3. Ma (all uncertainties are at 95% confidence unless otherwise specified) for the host sandstone. Igneous crystallization dates between 3380 and 3299. Ma were obtained for tonalite gneiss and foliated trondhjemite samples from widely dispersed sites, whereas unfoliated granitic samples provided igneous crystallization dates <3.3. Ga, thus constraining the time of regional deformation and amphibolite grade metamorphism to the interval c. 3325-3300. Ma. Volcanic, clastic sedimentary and banded iron-formation rocks assigned to the Iron Ore Group (IOG) are preserved around the margins of the Singhbhum Granite Complex. An igneous crystallization date of 3285. ±. 7. Ma, obtained for a biotite granodiorite that is overlain by conglomerate of the IOG, provides a maximum deposition age for components within the western (Jamda-Koira) IOG basin. A dacite tuff from the Malayagiri IOG basin south of Palalahara yielded an igneous crystallization date of 2806. ±. 6. Ma, confirming that the IOG as currently defined, includes unrelated sedimentary rocks that were deposited within different basins over an 800 Myr interval. Evolution of the Singhbhum Craton may be summarized as follows: (1) between 3530 and 3300. Ma, tonalites were emplaced, with volcanic, clastic and carbonate rocks and banded iron-formation (cycle 1) deposited onto tonalitic basement until 3375. Ma; (2) between 3325 and 3300. Ma, burial, deformation and uplift transformed the central part of the Singhbhum basement to tonalite gneisses, with cycle 1 sedimentary rocks incorporated into the gneisses as enclaves but preserved within synforms around the basement margins; post-3.3. Ga regional metamorphism granodiorite intrusions were emplaced until c. 3285. Ma; (3) BIF and clastic sedimentary rocks (cycle 2) were deposited around the margins of the craton onto the older (cycle 1) sedimentary rocks and adjacent gneissic basement until c. 3.1. Ga; (4) a further episode of granite intrusion at 3090. Ma was followed by uplift and erosion of the central part of the craton prior to 2806. Ma; (5) volcano-sedimentary and banded iron-formation rocks were deposited during a third sedimentary cycle at c. 2.8. Ga.},
keywords = {Geochronology, Radiometric age},
pubstate = {published},
tppubtype = {article}
}

@article{Nelson2006,
title = {CONCH: A Visual Basic program for interactive processing of ion-microprobe analytical data},
author = {D.R. Nelson},
url = {http://www.geochron.com.au/wp-content/uploads/2016/11/148.-Nelson-2006.pdf},
issn = {0098-3004},
year = {2006},
date = {2006-01-01},
journal = {Computers & Geosciences},
volume = {32},
number = {9},
pages = {1479--1498},
abstract = {A Visual Basic program for flexible, interactive processing of ion-microprobe data acquired for quantitative trace element, 26Al-26Mg, 53Mn-53Cr, 60Fe-60Ni and U-Ŧh-Pb geochronology applications is described. Đefault but editable run-tables enable software identification of secondary ion species analyzed and for characterization of the standard used. Counts obtained for each species may be displayed in plots against analysis time and edited interactively. Count outliers can be automatically identified via a set of editable count-rejection criteria and displayed for assessment. Standard analyses are distinguished from Unknowns by matching of the analysis label with a string specified in the Set-up dialog, and processed separately. A generalized routine writes background-corrected count rates, ratios and uncertainties, plus weighted means and uncertainties for Standards and Unknowns, to a spreadsheet that may be saved as a text-delimited file. Specialized routines process trace-element concentration, 26Al-26Mg, 53Mn-53Cr, 60Fe-60Ni, and Ŧh-U disequilibrium analysis types, and U-Ŧh-Pb isotopic data obtained for zircon, titanite, perovskite, monazite, xenotime and baddeleyite. Correction to measured Pb-isotopic, Pb/U and Pb/Ŧh ratios for the presence of common Pb may be made using measured 204Pb counts, or the 207Pb or 208Pb counts following subtraction from these of the radiogenic component. Common-Pb corrections may be made automatically, using a (user-specified) common-Pb isotopic composition appropriate for that on the sample surface, or for that incorporated within the mineral at the time of its crystallization, depending on whether the 204Pb count rate determined for the Unknown is substantially higher than the average 204Pb count rate for all session standards. Pb/U inter-element fractionation corrections are determined using an interactive loge-loge plot of common-Pb corrected 206Pb/238U ratios against any nominated fractionation-sensitive species pair (commonly 238U16O+/238U+) for session standards. Also displayed with this plot are calculated Pb/U and Pb/Ŧh calibration line regression slopes, y-intercepts, calibration uncertainties, standard 204Pb- and 208Pb-corrected 207Pb/206Pb dates and other parameters useful for assessment of the calibration-line data. Calibrated data for Unknowns may be automatically grouped according to calculated date and displayed in color on interactive Wetherill Concordia, Ŧera-Wasserburg Concordia, Linearized Gaussian ("Probability Paper") and Gaussian-summation probability density diagrams.},
keywords = {Data reduction, Geochronology, Isotope analysis, Radiometric age, Secondary ion mass spectrometry, SHRIMP, SIMS, Visual Basic},
pubstate = {published},
tppubtype = {article}
}

@article{Rigantietal2002,
title = {The geological setting of the Edale Shear Zone, central Yilgarn Craton},
author = {A. Riganti and S.F. Chen and D.R. Nelson and S. Wyche},
url = {http://www.geochron.com.au/wp-content/uploads/2016/11/114.-Riganti-et-al-2002.pdf},
year = {2002},
date = {2002-01-01},
journal = {Western Australia Geological Survey Extended Abstracts 2002},
keywords = {Geochronology},
pubstate = {published},
tppubtype = {article}
}