2771357
Persistent Identifier: https://pid.geoscience.gov.au/sample/AU2771357
| Property | Value |
|---|---|
| id | 2771357 |
| igsn | 10273/AU2771357 |
| sample_id | ERIVMAE1815.01 |
| eno | 628638 |
| sampling_feature_name | ERIVMAE1815 |
| sampling_feature_type | field site |
| sample_type | outcrop specimen |
| sampling_method | outcrop sampling |
| material_class | rock |
| earth_materials | Y |
| stratigraphic_unit | Caloola Dacite |
| geological_province | Central NSW - Omeo Province |
| sample_remark | Pale greyish-green, undeformed porphyritic Caloola Dacite. Phenocrysts comprise 1.5-4 mm euhedral plagioclase (15%) and lath-shaped hornblende up to 5 mm (5%). The rock also contains rare, fine-grained biotite-rich xenoliths up to 30 mm, some of which contain sillimanite (Eastlake, 2018). In thin section, the dacite comprises 20% phenocrysts of plagioclase and hornblende, in a very fine-grained, aphanitic to weakly spherulitic, quartzo-feldspathic groundmass. Plagioclase (16%) forms euhedral crystals 0.5-4.5 mm long, which are largely altered to secondary sericite +/- epidote. Hornblende (4-6%) forms 0.2-1.2 mm blades with width:length up to 1:5.5. Many hornblende phenocrysts are altered to chlorite +/- epidote. Accessory phases include apatite, zircon, and magnetite. A cognate inclusion at the corner of the slide (5 x 8 mm) is composed of aligned hornblende, with minor magnetite and rare interstitial feldspar. The matrix locally contains void infill structures less than 0.5 mm which contain radial clinozoisite +/- interstitial carbonate minerals, and pyramidal quartz terminations projecting into the void space. These outcrops are part of a NNW-trending dyke at least 70 m wide, which intrudes the 429.1 +/- 2.1 Ma S-type Belmore Granite (ERIVMAE1365.01). Similar magnetic features are present in the Ordovician Adaminaby Group, and these curve from N- to NNE-trending orientations. The Caloola Dacite has I-type mineralogy, and was targeted for U-Pb SHRIMP zircon geochronology to compare it to Early Devonian I-type plutonism to the SW, such as the 415.1 +/- 2.0 Ma Holbrook Granite and the 415.7 +/- 2.6 Ma Thologolong Granite (Bodorkos et al., 2015), and the 415.1 +/- 2.0 Ma Hawksview Granite (ERIVKFB0552.01). If the magnetic patterns represent a single set of coeval dykes, the Caloola Dacite will also establish a maximum age for the regional deformation event responsible for large-scale curvature of the dyke set. |
| 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 | 147.861033 |
| gda94_latitude | -35.462578 |
| sample_originator | Geological Survey of New South Wales (GSNSW) |
| date_acquired | 2018-05-09 00:00:00 |
| Links |
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