2771359
Persistent Identifier: https://pid.geoscience.gov.au/sample/AU2771359
| Property | Value |
|---|---|
| id | 2771359 |
| igsn | 10273/AU2771359 |
| sample_id | ERIVMAE1820.01 |
| eno | 628628 |
| sampling_feature_name | ERIVMAE1820 |
| sampling_feature_type | field site |
| sample_type | outcrop specimen |
| sampling_method | outcrop sampling |
| material_class | rock |
| earth_materials | Y |
| stratigraphic_unit | Wondalga Granodiorite |
| geological_province | Central NSW - Omeo Province |
| sample_remark | Medium-grained seriate inequigranular Wondalga Granodiorite featuring squat crystals of quartz 2.5-8 mm long, some of which have subtle pyramidal terminations. The rock contains rare, small microgranitic enclaves of intermediate composition, typically 15-20 mm across. In thin section, this medium-grained seriate biotite granodiorite comprises quartz (48%), plagioclase (36%), K-feldspar (8%) and biotite (7%), with accessory apatite, zircon and opaque oxide minerals. Rounded, sub-equant quartz phenocrysts 2-9 mm long make up about 12% of the rock. These commonly have embayed margins and some contain 'worm-like' infiltrations of K-feldspar. In both phenocrysts and groundmass, quartz shows undulose extinction and development of elongate subgrain boundaries. Plagioclase is 1-5 mm, and features distinct concentric 'euhedral' compositional zoning despite having anhedral crystal margins. K-feldspar (as microcline and perthite) forms irregular interstitial crystals less than 2 mm, and are lightly dusted with secondary clay minerals. Primary biotite is recrystallised into irregular aggregates of fine-grained pale green-brown to olive-green biotite that also commonly include magnetite and euhedral secondary epidote. Secondary sericite and fine-grained epidote are developed in the core regions of many plagioclase crystals. The Wondalga Granodiorite intrudes chemically-immature, mafic-derived sedimentary rocks of the Bangus Formation, which preserves a contact metamorphic aureole (Eastlake, 2020). It is flanked to the SW by the c. 435 Ma Nacka Nacka Metabasic Igneous Complex (Bell, 2020), and although the nature of the contact is largely obscured by the Wondalga Shear Zone (Basden, 1990; Eastlake, 2018), rare low-strain exposures preserve magma-mingling textures that suggest contemporaneity between the Nacka Nacka Metabasic Igneous Complex and the Wondalga Granodiorite (Eastlake, 2020). |
| 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 | 148.08334 |
| gda94_latitude | -35.299783 |
| sample_originator | Geological Survey of New South Wales (GSNSW) |
| date_acquired | 2018-05-10 00:00:00 |
| Links |
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