2771358
Persistent Identifier: https://pid.geoscience.gov.au/sample/AU2771358
| Property | Value |
|---|---|
| id | 2771358 |
| igsn | 10273/AU2771358 |
| sample_id | ERIVMAE1819.01 |
| eno | 628627 |
| sampling_feature_name | ERIVMAE1819 |
| sampling_feature_type | field site |
| sample_type | outcrop specimen |
| sampling_method | outcrop sampling |
| material_class | rock |
| earth_materials | Y |
| stratigraphic_unit | Ellerslie Granodiorite |
| geological_province | Central NSW - Omeo Province |
| sample_remark | Foliated, medium- to coarse-grained inequigranular biotite granodiorite of the Ellerslie Granodiorite. Weathered surfaces emphasise elongate quartz crystals 4-14 mm long. Euhedral, bone-coloured feldspars are 4-15 mm, with aspect ratios (length:width) up to 3:1. The granodiorite hosts sparse, ovoid-shaped microgranitoid enclaves (the largest of which is 40 x 14 cm, with most being much smaller) aligned to foliation. In thin section, the rock is composed of plagioclase (49%), quartz (32%), biotite (13%), K-feldspar (6%) and accessory apatite, zircon and xenotime. Plagioclase forms blocky 1-6 mm crystals with compositional zoning, and a diffuse cellular texture is developed in some cores. Quartz forms coarse-grained aggregates (up to 10 mm) of irregular crystals with undulose extinction, serrated quartz-quartz boundaries, and local subgrain development. Biotite forms subhedral plates (0.5-3 mm) and clustered aggregates, with straw to chocolate brown pleochroism. Very rare acicular rutile defines sagenitic texture. Iron-rich chlorite (+/- epidote) partially replaces biotite. K-feldspar is anhedral and less than 1.5 mm. Some show weak perthitic texture, and myrmekite replacements are developed at crystal margins. The Ellerslie Granodiorite is flanked to the E by the S-type Green Hills Granodiorite (428.3 +/- 2.1 Ma; Bodorkos et al., 2015), but is readily distinguished from the latter in ternary radiometric imagery (Eastlake, 2018). The predominant high thorium- and potassium-equivalent response of the Ellerslie Granodiorite results in green hues, which differ from the pale blue and purplish tones of the Green Hills Granodiorite. Chappell et al. (1991) classified the Ellerslie Granodiorite as a mafic, unfractionated, I-type. New observations and measurements by Eastlake (2020) support this interpretation: primary hornblende is present in minor tonalitic phases of the pluton, and a series of new geochemical analyses indicate a weakly peraluminous I-type affinity. |
| 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 | 147.91798 |
| gda94_latitude | -35.290365 |
| sample_originator | Geological Survey of New South Wales (GSNSW) |
| date_acquired | 2018-05-10 00:00:00 |
| Links |
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