9655246
Persistent Identifier: https://pid.geoscience.gov.au/sample/AU9655246
| Property | Value |
|---|---|
| id | 9655246 |
| igsn | 10.60494/hat6-4p02 |
| sample_id | Rook Tuff A+B |
| eno | 912541 |
| sampling_feature_name | Rook Tuff |
| sampling_feature_type | field site |
| sample_type | outcrop specimen |
| sampling_method | outcrop sampling |
| material_class | rock |
| stratigraphic_unit | Rook Tuff |
| geological_province | Stuart Shelf |
| sample_remark | Fanning et al. (1986): The Rook Tuff is a thin, partly volcanogenic silty unit within the early Adelaidean Callanna Group. This tuffaceous unit is confined to the N part of the Willouran Ranges which represent a NW extension of the Flinders Ranges. In the NE part of the Willouran Ranges, the Rook Tuff contains a thin (2-3 m), regionally lenticular interbed of porphyritic dacite with gradational upper and lower contacts. It is suggested that this interbed represents a welded tuff formed contemporaneously with early Adelaidean sedimentation. An initial sample (A) of the welded tuff was collected ~0.5 km NW of the eastern Rook workings, followed by a second sample (B) which was collected ~250 m along strike from the first, within the same tuffaceous horizon. Only 30-60 zircons were obtained from these two samples, so a total of 6 "single grain" analyses were carried out, carefully hand-selecting clear, pale yellow euhedral zircons. The three aliquots from sample A comprised one grain (27.9 ug), four grains (19.4 ug) and three grains (18 ug). The three aliquots from sample B comprised one grain (23.9 ug), two grains (15.7 ug) and two grains (10.4 ug). Five of the six analyses are coincident and concordant to within experimental errors, at 795-808 Ma. The sixth analysis records a slightly younger, barely discordant age, but the error ellipse overlaps the other five points on a Wetherill concordia plot. Given the general concordant nature of the data, a weighted average of the 207Pb/206Pb ages gives an age of 802 +/- 10 Ma (95% confidence), with MSWD = 2.4. The concordance of points and agreement to within analytical uncertainty indicates conclusively that the age of crystallisation of the zircon and the Rook Tuff occurred close to 800 Ma. |
| earth_materials | Y |
| structural_measurements | None |
| inorganic_geochemistry | None |
| organic_geochemistry | None |
| geochronology | None |
| isotope_groups | None |
| hydrochemistry | None |
| rock_properties | None |
| mineralogy | None |
| thin_sections | None |
| repository_samples | None |
| mineral_deposit_samples | None |
| mineral_deposit_waste_samples | None |
| linked_files | None |
| other_geological_data | None |
| project_name | EFTF - Isotopic Atlas of Australia |
| gda94_longitude | 137.9578026 |
| gda94_latitude | -29.8005483 |
| sample_originator | Fanning, C.M. |
| date_acquired | 2000-01-01 00:00:00 |
| Links |
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