2678823
Persistent Identifier: https://pid.geoscience.gov.au/sample/AU2678823
| Property | Value |
|---|---|
| id | 2678823 |
| igsn | 10273/AU2678823 |
| sample_id | R2427076 |
| eno | 625741 |
| sampling_feature_name | CDP001 |
| sampling_feature_type | borehole |
| sample_type | core |
| sampling_method | core diamond |
| material_class | rock |
| stratigraphic_unit | Koomalboogurra Suite |
| geological_province | None |
| sample_remark | Banded crystalline rock composed of diffuse bands ~2-5 mm wide. Felsic bands comprise pale pink K-feldspar, translucent grey quartz and blocky white plagioclase grains; mafic bands comprise small dark green to black plates aligned in the trace of banding. In thin section, this sample has a hypidiomorphic granitoid texture with mineralogical banding. K-feldspar (32%) forms ~1-2 mm subhedral grains with tartan twinning (microcline). Quartz (25%) forms unrecrystallised anhedral 0.4-2.0 mm grains with undulose extinction, and some are aligned in the trace of banding. Plagioclase (10%) forms subhedral equant 0.4-1.5 mm grains, partially replaced by optically continuous twinned albite lightly clouded by sericite flecks and uncommon small pale yellow zoisite. Clear relict primary plagioclase displays weak normal compositional zoning. Biotite (1%) forms euhedral 0.4-1.0 mm plates throughout the rock, but are notably more abundant in subparallel bands. Most biotite has been selectively replaced by pleochroic green chlorite, and uncommon zoisite and prehnite (subradiating, colourless, low to moderate birefringence). Relict biotite has straw yellow to dark brown pleochroism (moderately oxidised Fe-Mg biotite composition). Opaques form larger subhedral grains (magnetite, partially replaced by hematite) and smaller bladed grains (ilmenite). Minor apatite forms small stumpy colourless prisms in biotite, or at margins of opaque grains. Zircon occurs as ~100-150 um colourless prisms in size, in or near biotite. Rare thin discontinuous fractures, discordant to banding, are sealed by anhedral zoisite grains and aggregates of small chlorite flakes. INTERPRETATION: 1. Crystallisation of a weakly oxidised granitoid magma to form a monzogranite containing magnetite and ilmenite. 2. Deformation produced a banded gneissic rock. 3. Alteration generated new albite + sericite + chlorite + minor hematite + zoisite + prehnite after primary plagioclase, biotite and magnetite. |
| 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 | 129.256504 |
| gda94_latitude | -31.6376894 |
| sample_originator | Jagodzinski, E.A. |
| date_acquired | 2017-10-23 00:00:00 |
| Links |
|