Abstract Victorian Bluestone is proposed as a Global Heritage Stone Province from Australia. Numerous heritage stones occur within this province and of these Malmsbury Bluestone is suggested as a Global Heritage Stone Resource. Bluestone, an iconic basalt dimension stone from Victoria, is used domestically and internationally with a recognized heritage value. Sources are located in urban and country areas of Victoria some of which are still utilized for dimension stone. In many instances bluestone has superior technical characteristics, including durability, that surpass high-quality commercial sandstones, despite an architectural preference for lighter-coloured stones. These characteristics are matched by the diversity of significant uses for domestic, commercial and infrastructure purposes especially in Victoria. Notable examples include the Spotswood Pumping Station, Malmsbury Viaduct, the Graving Dock (Williamstown), Malmsbury Reservoir, St Patrick's Cathedral (Melbourne), Kyneton Railway Station and Ararat Gaol. If the bluestone used in pavements and drains is also considered, Victorian Bluestone could be described as Australia's most prominent infrastructure heritage stone. Bluestone use in Melbourne dates from the 1840s, in the other states of Australia and in New Zealand from 1873, with international interest from Asia between 1860 and 1880. The stone continues to be utilized widely around Australia and is also exported.

Abstract Cape Town was founded in 1652 and many of its historical buildings are constructed of local natural stone. Malmesbury Group slate was exploited from 1666 and used to build Cape Town Castle, which is the oldest building in Cape Town. Two other local stones, Cape granite and Table Mountain sandstone were utilized for buildings from 1850. A medium-grained granite named Paarl Grey was exploited from an area adjacent to the town of Paarl, 50 km east of Cape Town, from 1890. This granite is the most extensively-used natural stone in Cape Town. The resource fields of natural stone near Cape Town, namely Malmesbury Group slate, Cape granite and Table Mountain sandstone, lie within the Table Mountain National Park and Robben Island World Heritage Site and can no longer be exploited, but similar resource fields occur outside Cape Town. Paarl Grey granite is still extracted at one quarry and, despite part of the resource field lying within the Paarl Mountain Nature Reserve, there are still sufficient quantities of stone available. From an international perspective, the heritage stones of Cape Town, South Africa, are best considered as having national significance.

Abstract Stable isotope composition of gas is widely used in hydrocarbon exploration to determine the composition and thermal maturity of source rocks. Many isotope classification systems used for gas to source rock correlation and thermal maturity determination are primarily based on empirical observations made in conventional reservoirs and the kinetic isotope effects observed during pyrolysis experiments performed on source rocks. However, such relationships may not be readily applicable to onshore unconventional reservoirs due to the strong molecular and isotope fractionation that occur during extensive gas expulsion associated with basin uplift and depressurization. Degassing studies of freshly recovered core samples can provide useful insight into the behaviour of gas molecules in unconventional reservoirs during basin uplift. The analyses of Australian coal and marine shale samples demonstrate that during desorption both molecular and isotopic compositions of gas change at variable rates. Gas initially desorbed from the samples is mostly CH 4 , whereas later desorbed gas becomes increasingly enriched in C 2 H 6 and higher hydrocarbons. Hydrocarbon molecules also fractionate according to their isotopic composition, where the early released gas is enriched in 12 C causing the remaining gas in the reservoir to be enriched in the heavier 13 C isotope. During the release of gas from the Bowen Basin coals the C isotope ratio of CH 4 (δ 13 C 1) changes by up to 21‰ (VPDB), whereas that for C 2 H 6 (δ 13 C 2) and C 3 H 8 (δ 13 C 3) changes by <6‰. Similar changes in the isotope composition can be seen during the release of gas from marine source rocks of the Beetaloo Sub-basin. In a fully gas-mature middle Velkerri shale sample, δ 13 C 1 changes by up to 28‰ and δ 13 C 2 by up to 3‰ with no appreciable change occurring in δ 13 C 3 . The extent of molecular fractionation during gas flow through carbonaceous rocks is primarily related to the adsorption–desorption properties of organic matter and diffusivity through the overall rock matrix. Using the current dataset, the magnitude of the contributions exerted by the desorption and diffusion processes cannot be readily distinguished. However, both Bowen Basin coals and Beetaloo Sub-basin shale show similar fractionation effects during gas flow, where the heavier alkane molecules, including those containing more 13 C, desorb and move slowly compared with the lighter components, in particular CH 4 . Different rates of isotope fractionation between hydrocarbon molecules during gas flow cause the shape of compound-specific-isotope (CSI) curve to change with time. Early released gas is characterized by a normal CSI trend where the short-chain hydrocarbons are isotopically lighter compared with the longer-chain hydrocarbons. Because CH 4 and C 2 H 6 molecules enriched in 12 C desorb and diffuse more readily than the heavier hydrocarbons (including those enriched 13 C), the gas remaining in the coal and shale samples after extensive desorption shows a reversed CSI trend where CH 4 and C 2 H 6 are isotopically heavier compared with the longer chain hydrocarbons. Reversed isotope trends may also develop over geological time, particularly where the source rock is fully gas-mature and has expelled hydrocarbons due to prolonged degassing. As seen in the Beetaloo Sub-basin, the CSI trend in the dry-gas-mature Velkerri shale is reversed, possibly due to the loss of a large proportion of originally generated CH 4 during post-Cambrian basin uplift.

Abstract The relationship between pore structures was examined using a combination of normalized topographical and topological measurements in two qualitatively different pore systems: organic-hosted porosity, common in unconventional shale reservoirs; and intergranular porosity, common in conventional siliciclastic reservoirs. The organic-hosted pore network was found to be less well connected than the intergranular pore network, with volume-weighted coordination numbers of 1.16 and 8.14 for organic-hosted and intergranular pore systems, respectively. This disparity in coordination number was explained by differences in the pore shapes that are caused by variations in the geological processes associated with the generation of the pore network. Measurements of pore shape showed that the pores in the organic-hosted network were both significantly more spherical and had a more positive curvature distribution than the pores present within the intergranular network. The impact of such changes in pore shape on pore-network connectivity was examined by creating a suite of synthetic pore geometries using both erosion/dilation of the existing network and image-guided object-based methods. Coordination number, Euler characteristic and aggregate porosity analyses performed on these synthetic networks showed that organic-type pore networks become connected at much higher aggregate porosities (35–50%) than intergranular-type pore networks (5–10%).