9652132
Persistent Identifier: https://pid.geoscience.gov.au/sample/AU9652132
| Property | Value |
|---|---|
| id | 9652132 |
| igsn | 10.60494/rf91-5010 |
| sample_id | 2023330034 |
| eno | 867077 |
| sampling_feature_name | NDIWMP02 |
| 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 NDIWMP02 samples a prominent NE-trending magnetic lineament. Magmatic units in this hole are magnetic and are probably the cause of the magnetic anomaly. The sedimentary rocks towards the bottom of the hole are less magnetic. This hole was drilled using a conventional diamond drill-rig, reached a total depth of 646.3 m, and recovered about 100 m of diamond core. The primary lithologies in the hole are (1) an intermediate porphyritic intrusion (represented by samples 9652125/2023330042 and 9652129/2023330043), which occurs above a (2) fine- to medium-grained siliciclastic unit (represented by current sample 9652132/2023330034). Contact between both units occurs across ~10 cm and is altered and fractured, making the primary nature of the contact unclear. The porphyritic unit varies subtly between a more aphanitic and aphyric phase (represented by sample 9652129/2023330043) and a more porphyritic phase (represented by sample 9652125/2023330042), although there is no clear boundary. In terms of alteration, the entire core, including the siliciclastic rock, is variably altered (mostly pinkish hematite staining of albite, with some lighter-coloured alteration (sericite?) surrounding fractures and veins). Zoned plagioclase phenocrysts within the porphyry are commonly altered to a pale greenish colour. Sample 9652132/2023330034 was taken from the lower interval of grey, medium-grained, equigranular intermediate rock, which largely comprised ~1 mm grains of white (plagioclase?) and dark grey (biotite/hornblende?) minerals. At macro-scale, it was not possible to determine whether the rock was igneous or sedimentary, but petrographic work confirmed it as a hornfelsed sandstone (feldspathic metagreywacke). The Zr content obtained by pXRF was high (840 ppm). In thin section, sample 9652132/2023330034 is a medium- to coarse-grained felspathic metagreywacke. The sandstone has a well-developed imbrication, defined by tabular quartz and feldspar and the matrix is extensively recrystallised and biotite flooded. The sample is 45% quartz, 15-20% feldspar, 5% lithics and up to 30% recrystallised matrix. Given the mineralogy of the sandstone a granite dominant source is likely. Quartz is by far the most dominant framework grain, occurring as angular to sub-rounded, tabular grains (0.5-0.9 mm) with low to moderate sphericity. Grains are optically clear with fine fluid inclusions trails, display undulose extinction, and may be sub-grained. Feldspar (plagioclase and K-feldspar) grains typically retain their tabular, blocky form and are of a similar grain-size range to quartz. Plagioclase is albitic in composition, while K-feldspar is often perthitic. It is difficult to estimate the abundance of lithic clasts due to the extensive recrystallisation, but a few coarser-grained, strongly recrystallised very fine-grained sandstone to siltstone lithics are still discernible. Accessory phases include rounded/elliptical zircon, apatite, very minor fine-grained pyrite and magnetite and very rare tourmaline. The matrix of the sandstone comprises a very fine-grained (0.04-0.07 mm) recrystallised polygonal mosaic dominated by quartz and red-brown biotite. Biotite also occurs in decussate masses surrounding Fe-Ti-oxide minerals. The sandstone is cut by a few very narrow carbonate veins and biotite is locally replaced by a pale green chlorite. The lack of deformation, pervasive recrystallisation and secondary mineralogy of the sandstone is consistent with biotite-hornfels facies metamorphism. The abundance of secondary biotite is consistent with moderate biotite alteration of the sample synchronous with contact metamorphism that formed the hornfels. |
| 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 | 141.62446 |
| gda94_latitude | -33.49948 |
| sample_originator | Clark, A. |
| date_acquired | 2023-11-26 00:00:00 |
| Links |
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