EGPR 7 - Melbourne Metropolitan Basalt Survey geoscience data modernisation.
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Product description:Executive Summary:The Newer Volcanic Group has been, and continues to be, an important source rock in Victoria, accounting for 54% of total hard rock construction material production in 2022. From 1975-1977 the Geological Survey of Victoria (GSV) undertook the Melbourne Metropolitan Basalt Survey (the survey) in the western and northern outskirts of greater Melbourne to evaluate the Newer Volcanic Group for aggregate production. The survey comprised a semi-regional grid of 111 vertical diamond drill holes for a total of 6,629.05 m. The findings of the survey were captured in hard copy reports that have since been scanned and made available in the GSV catalogue. To modernise the geoscience data captured by the survey, and most importantly make the data in the reports accessible and usable, 109 (of 111) drill hole logs were identified, extracted, digitised, and validated for downhole lithology and associated metadata. In addition, for select intervals of the 94 (of 111) diamond drill holes remaining at the GSV Drill Core Library, the following value-add activities were undertaken: • Core photography of each tray of each drill hole, with all photos made available through GeoVic. • Modern engineering geoscience test work, comprising 52 samples from 26 drill holes for 371 individual test results, which when combined with 28 legacy test results for a total of 399 individual test results now available for analysis. The resulting drilling and sample data was centralised in a contemporary drill hole database. An analysis of relevant data against current Australian and VicRoads standards has confirmed the suitability of Newer Volcanic Group basalt for aggregate production across the survey area based on the following key findings: • Almost all (91%) of wet/dry strength variation values were < 45%. • Almost all (90%) of the aggregate soundness values had a total weighted average loss < 6%. • The majority (82.1%) of LA abrasion values correspond with Class A aggregate, which is commonly used as a sealing aggregate for roads, car parks, pathways and hard standing areas. Almost all (96.1%) of the drill holes returned a calculated source rock to waste ratio of > 1 to 1, which is considered favourable for quarry development and operation. The incorporation of basalt intervals below a depth of 25 m, which was previously considered the depth of economic extraction, resulted in a higher average source rock to waste ratio. This suggests that there is the potential for the production of construction materials from prospective basalt at depths greater than previously considered. Understanding the mineralogy and hydrogeology will be key geoscience considerations as part of any further source rock to waste ratio evaluation. Additional engineering geoscience test work for Newer Volcanic Group basalt and related rocks (e.g. scoria), from industry and/or government, within and beyond the survey area, will further strengthen the evidence base for informed analysis and decision making on prospective source rock and extractive resources. Bibliographic Reference: Haar, C.L., Travers, S.J. & Drochmann, T.K., 2024. Melbourne Metropolitan Basalt Survey geoscience data modernisation. Extractives Geoscience Project Report 7. Geological Survey of Victoria. Department of Energy, Environment and Climate Action, 53 pp. Download: The downloadable version of this report is supplied in PDF format (33 MB), Attachment A1 (ZIP 20MB), Attachment A2 (ZIP 2.5 MB) & Attachment A3 (ZIP 12 MB). | ||||||
