9652134
Persistent Identifier: https://pid.geoscience.gov.au/sample/AU9652134
| Property | Value |
|---|---|
| id | 9652134 |
| igsn | 10.60494/xm6y-cq72 |
| sample_id | 2023330041 |
| eno | 867080 |
| sampling_feature_name | NDIWMP03 |
| sampling_feature_type | borehole |
| sample_type | half core |
| sampling_method | core drilling |
| material_class | rock |
| stratigraphic_unit | None |
| geological_province | Delamerian Orogen |
| sample_remark | Mole et al. (2024): Drillhole NDIWMP03 samples a large, irregular magnetic anomaly. Sample 9652134/2023330041 was taken from a conventional diamond drill-hole that intersected one unit; a medium- to coarse-grained (and magnetic) hornblende granodiorite. The unit is variably altered to a pinkish colour around minor veins, as well as pale greenish-grey in some intervals. There is no evidence for multiple intrusive phases. Enclaves/xenoliths are common and mostly consist of medium-grained mafic rocks (dolerite/diorite) with a transitional matrix/margin between the enclave and the granodiorite. Other xenoliths exhibit strong foliation and are more felsic/metasedimentary in appearance. Sample 9652134/2023330041 was taken from the least-altered and veined interval of medium- to coarse-grained hornblende granodiorite. No major xenoliths or enclaves were observed in the sampled interval, which yielded a pXRF Zr content of 70-170 ppm. In thin section, sample 9652134/2023330041 is a medium-grained biotite-hornblende granodiorite of I-type affinity. The sample has a weakly porphyritic texture, with medium-grained quartz surrounded by intergrown plagioclase, hornblende, and biotite. Point-counted (>300 points) modal mineralogy is 18% K-feldspar, 27% quartz, 33% plagioclase, 11% biotite, 11% hornblende and 1% opaques (normalised QAP = 35-23-42; granodiorite/granite). A diorite enclave (20 mm wide) is present in the centre of the thin section. The overall texture of the granodiorite involves relatively coarse, equant to rounded, weakly graphic-textured quartz surrounded by a network of intergrown feldspar and ferromagnesian minerals. Plagioclase is the most abundant feldspar, occurring as stout tabular grains 0.5-1 mm in size. Grains display well-developed normal zonation from more calcic cores (partially replaced by sericitic white mica and epidote) to more optically clear albitic rims; oscillatory zonation is common within the overall normal zonation. Although the calcic cores can display simple and polysynthetic twinning, most twins are indistinct or blurry and this combined with the strong replacement makes anorthite content impossible to estimate; albitic rims are typically untwinned. K-felspar is present as anhedral, interstitial grains up to 2.5 mm that are moulded around and may include plagioclase and ferromagnesian phases. Hematite dusting of K-feldspar is common. Quartz occurs as rounded clusters of grains, or single grains up to 5 mm. Grains typically host discontinuous trails or networks of finer-grained plagioclase and/or K-feldspar forming weak graphic-style intergrowths. Hornblende is typically subhedral to euhedral, tabular to diamond-shaped, occurring as <2.5 mm grains with brown-green to straw pleochroism. Many grains are partially replaced by acicular masses of blue-green actinolite or vermicular chlorite. Biotite occurs as stout books mostly up to 1 mm with common subhedral to euhedral hexagonal cross section. Biotite pleochroism varies from dark brown to straw, although many grains are partially to completely replaced by chlorite and radiating masses of epidote. Magnetite is present in low abundance, as equant (0.1-0.2 mm) inclusions to hornblende and biotite. Zircon is a common accessory phase, mostly as inclusions to biotite and fine needles of apatite are commonly included to feldspars. The diorite enclave is similar in grainsize but lacks abundant coarse quartz and has significantly less K-feldspar. Minerals within the enclave are also more strongly replaced by secondary minerals. The well-developed secondary mineralogy in the granodiorite reflects typical epizonal deuteric alteration and involves actinolite after hornblende, chlorite and epidote after biotite, and epidote and sericite after plagioclase. |
| 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 | EFTF - Darling-Curnamona-Delamarian (DCD) |
| gda94_longitude | 141.42508 |
| gda94_latitude | -33.768776 |
| sample_originator | Clark, A. |
| date_acquired | 2023-11-26 00:00:00 |
| Links |
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