Abstract Petroleum geochemistry has historically relied on the analysis of field samples – source rocks, oils and gases. Data collected for individual samples are considered characteristic of a specific geographical location and geological position that, when aggregated with data from other samples, can be extrapolated to larger scales. These scale-ups may be as small as a few metres, such as a detailed characterization of source rocks penetrated by a single well, to global, such as petroleum systems that now span continents due to plate tectonics. However, a single sample contains a wealth of information at smaller scales. In situ analytical techniques have improved significantly over the last decade, allowing us to examine sedimentary rocks at ever higher spatial (areal and temporal) resolution. Mass spectrometric imaging is an emerging, enabling technology that can be performed at c. 200 µm (matrix-assisted laser desorption) to 50 nm (nanoSIMS) resolution. X-ray microcomputed tomography (µ-CT) is being applied to examine the storage and transport of petroleum in low-permeability shales and carbonates at spatial resolutions as low as c. 8 µm. Pore architecture in shale, both organic and inorganic, can be modelled from small-angle neutron scattering (SANS) data and imaged directly with helium ion microscopy at c. 1 nm resolution. Atomic force microscopy (AFM) can now resolve the molecular structure of individual asphaltene molecules. Information obtained with these techniques is now revealing the fundamental nature of geological organic materials, opening the span of petroleum geochemistry from atoms to continents.

Abstract Microanalysis can provide rapid, quantitative characterization of mineral systems that complements the field- and core-scale observations traditionally made in ore deposits. We review recent innovations in microanalytical procedures and their application to studies of ore deposits. Case studies are presented examining how microanalysis can provide constraints on macroscopic processes within mineral systems. Synchrotron X-ray fluorescence shows centimetre-scale chemical variations associated with proximity to mineralization in samples from Sunrise Dam Gold Mine, Western Australia. Pseudomorphs of igneous plagioclase and chemically driven recrystallization interpreted from electron backscatter diffraction suggest that the system was dominated by fluid-driven brecciation with very little shearing. Both the fluid chemistry and fluid pressure evolved during a protracted sequence of vein formation and alteration accompanying gold mineralization. A second case study of sulphide mineralogy at the Mt Keith nickel sulphide deposit, Western Australia demonstrates how X-ray computed tomography combined with trace element mapping can constrain the chemistry and dynamics of magmatic systems. Large-scale interaction between silicate and sulphide melts, shown by homogenous palladium enrichment in pentlandite, leads to a large proportion of globular ores with a high nickel content. Increasing use of microanalysis in ore deposit geology is resulting in the constant reassessment of established models for ore genesis though a combination of micro- and macroscale datasets.