9964916
Persistent Identifier: https://pid.geoscience.gov.au/sample/AU9964916
| Property | Value |
|---|---|
| id | 9964916 |
| igsn | 10.60494/a1h8-aw76 |
| sample_id | BB1427 |
| eno | 929471 |
| sampling_feature_name | BB1427 |
| sampling_feature_type | field site |
| sample_type | outcrop specimen |
| sampling_method | outcrop sampling |
| material_class | rock |
| stratigraphic_unit | Bartle Frere Granite |
| geological_province | None |
| sample_remark | Sample 9964916 consists of white to grey, medium-grained, moderately porphyritic hornblende-biotite monzogranite. Modal analysis indicates K-feldspar (ca 29%) and plagioclase (ca 33%) in roughly equal amounts (Bultitude & Champion, 1992), with K-feldspar forming scattered euhedral-subhedral phenocrysts up to ca 20 mm long as well as smaller more irregular groundmass grains. Quartz (ca 26%) is the other main component as anhedral, pale grey grains in the groundmass. Mafic minerals (ca 11%) are dominated by biotite. No enclaves were detected in the boulder sampled but inclusions (up to ca 40 cm across) of biotite-rich gneiss were detected in boulders farther north near North Peak. The granite appears massive, undeformed in outcrop and shows minor reddish brown secondary iron oxide staining and some partly sericitised plagioclase grains. Thin section examination confirms the monzogranite (average grainsize ca 1.5 mm) consists mainly of plagioclase, K-feldspar and quartz with minor biotite (ca 8%) and hornblende (ca 3%), and accessory amounts of ilmenite, apatite and zircon. K-feldspar crystallised relatively late and forms large, irregular, anhedral to subhedral (scarce) vein and patch microperthites and much smaller interstitial groundmass grains. The larger grains contain inclusions of biotite, zircon, plagioclase and quartz. Plagioclase grains commonly show normal zoning (from cores of andesine, very rarely labradorite, to rims of oligoclase or albite; see Bultitude & Champion, 1992). The larger plagioclase grains commonly contain inclusions of biotite, quartz, ilmenite, zircon, and hornblende. The calcic cores of some grains have been variably sericitised. Quartz grains display undulose extinction with some subgrain development. Biotite and hornblende are interstitial to the quartz and feldspar grains. Hornblende forms subhedral to anhedral, brown to greenish brown grains, and biotite mainly equant grains that commonly have a somewhat ragged appearance and show minor alteration to chlorite. The opaque oxide is ilmenite (confirmed by microprobe analysis — see Bultitude & Champion, 1992) in keeping with the reduced character of the granite. Traces of titanite, allanite and tourmaline have also been reported in the granite (Bultitude & Champion, 1992). The only obvious indication of deformation is undulose extinction and some subgrain development displayed by quartz grains in thin section. |
| earth_materials | Y |
| structural_measurements | None |
| inorganic_geochemistry | None |
| organic_geochemistry | None |
| geochronology | Y |
| 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 | 145.8175468 |
| gda94_latitude | -17.4009756 |
| sample_originator | Bultitude, R.J. |
| date_acquired | None |
| Links |
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