2771364
Persistent Identifier: https://pid.geoscience.gov.au/sample/AU2771364
| Property | Value |
|---|---|
| id | 2771364 |
| igsn | 10273/AU2771364 |
| sample_id | ERIVSJT1197.01 |
| eno | 628633 |
| sampling_feature_name | ERIVSJT1197 |
| sampling_feature_type | field site |
| sample_type | outcrop specimen |
| sampling_method | outcrop sampling |
| material_class | rock |
| earth_materials | Y |
| stratigraphic_unit | Square Head Formation |
| geological_province | Central NSW - Omeo Province |
| sample_remark | Low rubbly outcrop on private property 'Hillcrest', about 600 m NNW of the homestead. The site is 3.5 km SSE of Beness Hill, and about 3 km WNW of Colinroobie. Rocks in this area belong to the Square Head Formation (Colquhoun et al., 2005) and lie within the Beness Syncline. Locally, strata dip 50 to the SE (Trigg, 2018). The rock sampled was described in the field as a weakly foliated sandstone. In thin section, however, this rock appears to be a foliated volcanogenic mudstone (K.F. Bull in Trigg, 2018) featuring 10% angular and irregularly distributed 0.1-0.3 mm quartz crystal fragments, possible lithic grains of siltstone and claystone up to sand-size, and subrounded tourmaline. The foliation is defined by wispy bands of sericite and iron oxide minerals, and some of the bands are kinked. Iron oxide minerals also form clusters and aggregates about the same size as the quartz crystal fragments, and these may have been former ferromagnesian crystals. The matrix is isotropic, and is interpreted as tuffaceous on the basis of its resemblance to recrystallised glass. However, no pyroclasts were recognised, and the presence of lithic grains and subrounded tourmaline grains indicates that the rock is at least in part detrital in origin. Age constraints for the Square Head Formation are limited. It unconformably overlies Early to Middle Ordovician metasedimentary rocks (Trigg, 2017) of the Abercrombie Formation of the Adaminaby Group (formerly the Wagga Group; Deyssing et al., 2018), and is in turn unconformably overlain by the Middle to Late Devonian Barrat Formation (Trigg, 2018). Based on regional correlations, Colquhoun et al. (2005) assigned a late Silurian to Early Devonian age to the Square Head Formation; however, this unit lacks fossils, and this possibly tuffaceous sandstone was targeted for U-Pb SHRIMP geochronology of detrital zircons in order to better constrain its depositional age. |
| structural_measurements | None |
| inorganic_geochemistry | Y |
| organic_geochemistry | None |
| geochronology | Y |
| isotope_groups | None |
| hydrochemistry | None |
| rock_properties | None |
| mineralogy | None |
| thin_sections | None |
| repository_samples | Y |
| mineral_deposit_samples | None |
| mineral_deposit_waste_samples | None |
| linked_files | None |
| other_geological_data | None |
| project_name | None |
| gda94_longitude | 146.545318 |
| gda94_latitude | -34.436795 |
| sample_originator | Geological Survey of New South Wales (GSNSW) |
| date_acquired | 2018-05-09 00:00:00 |
| Links |
|