2172119
Persistent Identifier: https://pid.geoscience.gov.au/sample/AU2172119
| Property | Value |
|---|---|
| id | 2172119 |
| igsn | 10273/AU2172119 |
| sample_id | BB5481A |
| eno | 577535 |
| sampling_feature_name | BB5481A |
| sampling_feature_type | field site |
| sample_type | outcrop specimen |
| sampling_method | outcrop sampling |
| material_class | rock |
| stratigraphic_unit | OK Member |
| geological_province | Hodgkinson Province |
| sample_remark | The OK Member is a narrow, chert-dominated belt on the eastern margin of the Kitoba Member, near the western margin of the Hodgkinson Province. It is also structurally intercalated with Kitoba Member rocks to the north, and therefore might be expected to form one of the oldest parts of the Hodgkinson Formation. However, radiolaria with three-bladed spines, which are considered characteristic of late Devonian (or younger) strata, occur in chert samples collected from the southeastern part of the member (24 km SE of Bellevue homestead), so an interlayered sandstone was sampled for analysis, to check the radiolarian age and to compare the detrital-zircon provenance spectrum with those from sandstones elsewhere in the Hodgkinson Formation. The sample was collected on the southern bank of the Mitchell River, from a thick sandstone bed interlayered with strongly cleaved, thin-bedded siltstone and dark grey mudstone. The sandstone is strongly indurated, very competent, relatively coarse-grained and poorly sorted, with 15-20% matrix. Framework grains are 0.3-3 mm (average 0.6 mm), mostly angular to subangular (some are subrounded), and dominated by monocrystalline quartz (65%). The sandstone also contains sparse polycrystalline quartz up to 1 mm; feldspar (8%) comprising plagioclase (partly replaced by sericite +/- calcite) and turbid K-feldspar (extensively replaced by clay minerals) in roughly equal amounts; lithic fragments up to 2 mm (5%) comprising fine-grained quartzite, ribbon quartz, mudstone, and rare feldspathic quartzite, mafic volcanics and chert; detrital muscovite up to 1 mm (2-3%); rare, small biotite (largely replaced by chlorite); interstitial calcite, and zircon. Widespread evidence for deformation and compaction includes: ubiquitous undulose extinction (and some incipient subgrain development) in monocrystalline quartz; undulose extinction and bent cleavage planes in muscovite, and curved twin planes or fracturing in some plagioclase grains. |
| earth_materials | Y |
| 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 | 144.2237296 |
| gda94_latitude | -16.4577982 |
| sample_originator | Kositcin, N. |
| date_acquired | None |
| Links |
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