2678308
Persistent Identifier: https://pid.geoscience.gov.au/sample/AU2678308
| Property | Value |
|---|---|
| id | 2678308 |
| igsn | 10273/AU2678308 |
| sample_id | NSWSJAF0176.01A |
| eno | 621276 |
| sampling_feature_name | DD17C10008 |
| sampling_feature_type | borehole |
| sample_type | core |
| sampling_method | core diamond |
| material_class | rock |
| stratigraphic_unit | Carissa Shaft porphyry |
| geological_province | Cobar Basin |
| sample_remark | This sample of pale grey, sparsely quartz-feldspar-phyric rhyolitic I-type porphyry was taken from diamond drillhole DD17C10008 (197-200 m) at Carissa Shaft, about 20 km SE of Cobar. This porphyry intrudes the sandstone-dominated Nurri Group of the Cobar Supergroup, and is one of the southernmost known porphyries associated with the major Perseverance and Queen Bee deposits within the Cobar mining belt (Gilligan and Byrnes, 1995). Black (2005) determined a U-Pb SHRIMP zircon age of 417.6 +/- 3.0 Ma for the Queen Bee Porphyry, which is significantly younger than the informally-named "Peak rhyolite" (423.2 +/- 3.5 Ma; Black, 2007) within the Chesney Formation of the Nurri Group. However, Bodorkos et al. (2013) dated a different sample of the flow-foliated "Peak rhyolite" at 418.3 +/- 3.0 Ma, coeval with the Queen Bee Porphyry. They suggested that either the two dated "Peak rhyolite" samples reflect two discrete eruptive episodes, or the Black (2007) date is slightly too old (owing to incorporation of marginally older inheritance and/or misattribution of some of the youngest zircon spot-dates to loss of radiogenic Pb). This sample was targeted for SHRIMP to better constrain the age range of shallow-level I-type intrusions associated with the Perseverance and Queen Bee deposits. In thin section, this porphyritic rhyolite features K-feldspar, plagioclase and quartz phenocrysts up to 5 mm in a matrix comprising a quartzofeldspathic mosaic. Feldspars are mostly stout laths, with plagioclase partially to completely replaced by possibly peritectic K-feldspar. Quartz phenocrysts are subhedral and commonly embayed. Clots up to 2-3 mm long, comprising chlorite-muscovite-titanite-opaque oxide minerals, are scattered through the matrix, and often preserve hexagonal crystal outlines inherited from the primary ferromagnesian igneous phase (biotite or pyroxene). The rock is crosscut by veins comprising chlorite, quartz and carbonate minerals, and narrow breccia zones. |
| 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 | 145.981793 |
| gda94_latitude | -31.640106 |
| sample_originator | Geological Survey of New South Wales (GSNSW) |
| date_acquired | 2017-08-30 00:00:00 |
| Links |
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