9655748
Persistent Identifier: https://pid.geoscience.gov.au/sample/AU9655748
| Property | Value |
|---|---|
| id | 9655748 |
| igsn | 10.60494/dysz-5p74 |
| sample_id | 76-3A |
| eno | 917363 |
| sampling_feature_name | 76-3A |
| sampling_feature_type | field site |
| sample_type | outcrop specimen |
| sampling_method | outcrop sampling |
| material_class | rock |
| stratigraphic_unit | Cooma Granodiorite |
| geological_province | Lachlan Orogen |
| sample_remark | Williams 2001 paraphrased: "Sample 76-3A was collected from a large fresh boulder excavated from a deep road cut on the flank of Nanny Goat Hill in Cooma township. The granodiorite is medium grained & massive & contains a high abundance of enclaves on all scales from small clots of minerals to rock fragments up to 0.5 m diameter. The enclaves all of sedimentary derivation can be matched closely with many of the highest grade rocks in the regional aureole including metapsammite biotite schist & b&ed gneiss. The granodiorite is exceedingly quartz rich (~50%) & unequilibrated mineralogically. Aluminous phases include biotite muscovite ragged sieved & alusite up to 2 mm cordierite phenocrysts up to 15 mm (most now pinitised) & mats of fibrolitic sillimanite. K-feldspar crystals up to 4 mm commonly have myrmekite developed at their margins & plagioclase more abundant than in the migmatites commonly occurs as zoned tabular grains with calcic cores. Biotite is crowded with pleochroic haloes around inclusions of zircon & monazite. Zircon is very abundant in the Cooma Granodiorite mostly sharply euhedral & with a very similar grainsize range to zircon in the low-grade semipelites (30-250 um). It is however a complex population. Although euhedral grains dominate a few crystals are strongly rounded & the frosted surface characteristic of detrital zircon is clearly visible under an optical microscope. Aspect ratios range from 1 to ~5. Terminations with strongly developed faces predominate particularly on the larger & more equant crystals but very simple prismatic crystals with only prisms & pyramids are common among the finer grains. Cathodoluminescence images reveal the reason for this variety. Virtually all zircons contain a core & it was principally the size & shape of that core that determined the size & shape of the final crystal. At one end of the spectrum are crystals in which the core is very large (>100 um) & strongly rounded. |
| 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 | None |
| gda94_longitude | 149.130717 |
| gda94_latitude | -36.230175 |
| sample_originator | Williams, S. |
| date_acquired | 3000-01-01 00:00:00 |
| Links |
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