Detailed studies of morphological, micromorphological and geochemical characteristics of silcretes in the deep bleached and weathered regolith across a large area of inland Australia have provided a new interpretation of the history of the regolith and its climatic and morphological evolution during the Tertiary. Pedogenic silcretes have distinctive morphological and mineralogical features caused by a succession of phases of silica dissolution and recrystallization resulting from multiple episodes of water infiltration and percolation under alternately wet and dry climates. These are the oldest of the regolith features. Deep, bleached profiles formed over a wide area in a variety of substrates ranging from Precambrian granites to Palaeozoic sandstones, Cretaceous sediments and Tertiary deposits, and represent the second major stage in regolith development. These profiles, in which kaolinite coexists with gypsum, alunite and opal, formed by reaction of the substrates with saline groundwaters, the water-table levels of which progressively fell over the region. Extensive networks of termite burrows constructed to great depth in the bleached regolith followed the water tables down. The climate was warm and dry with a high water deficit. Groundwater silcretes formed near-horizontal lenses and pods of porcellanite and jasper in the bleached regolith. They preserve the primary fabric of the host rock. Groundwater silcretes post-date the construction of termite burrows and were formed during a rise in groundwater tables across the landscape, in places to near-surface environments in broad landscape depressions. The climate was more humid but the presence of gypsum during silicification demonstrates that the groundwaters were still saline. Red-brown hardpans are the youngest silicification features and represent periods of successive infiltration and percolation, and waterlogging, during high rainfall or flood events. They are confined to low regions in the landscape. Mineralogical and geochemical analysis of the bleached profiles, together with geochemical modelling, suggests that ferrolysis is the most likely cause of acidity in groundwater leading to the development of the bleach profiles and/or alunite. Present-day groundwater tables are both at low levels and sulphate-rich. It is possible that acidic alteration leading to bleaching is still active around the extensive playa landscapes in the region.

Biodiversity offsets aim to compensate the negative residual impacts of development projects on biodiversity, including ecosystem functions, uses by people and cultural values. Conceptually, ecosystem services (ES) should be considered, but in practice this integration rarely occurs. Their consideration would improve the societal impact of biodiversity offsets. However, the prioritisation of ES in a given area is still limited. We developed a framework for this purpose, applied in rangelands landscapes in Kazakhstan, in the context of uranium mining. We assumed that different landscapes provide different ES, and that stakeholders perceive ES according to their category (e.g., elders and herders) and gender. We performed qualitative, semi-structured interviews with a range of stakeholders. Using the Common International Classification of Ecosystem Services, we identified 300 ES in 31 classes across 8 landscape units. We produced a systemic representation of the provision of ES across the landscapes. We showed a significant link between ES and landscape units, but not between ES and stakeholder categories or gender. Stakeholders mostly identified ES according to the location of their villages. Therefore, we suggest that the biodiversity offsets should target ES provided by the landscape unit where mining activities occur and would be most interesting in the landscapes common to all villages. By performing a systemic representation, potential impacts of some offset strategies can be predicted. The framework was therefore effective in determining a bundle of ES at a landscape scale, and in prioritising them for future biodiversity offset plans.