Abstract A multiproxy approach for evaluating palaeoclimate parameters in deep-time can result in improvements to inter-related factors affecting palaeohydrology. Here we utilize diverse geochemical tools to improve palaeoclimate estimates for the Cedar Mountain Formation (CMF). Prior research utilized stable carbon and oxygen isotopes to develop chemostratigraphic correlations to the late Aptian–early Albian, hypothesized aridity during a positive carbon isotope excursion (CIE) and estimated p CO 2 through this event. This study refines estimates using petrographical analyses, bulk geochemical proxies for mean annual precipitation (MAP) and clumped isotope palaeothermometry. MAP rates range from 736 to 1042 mm a −1 with a slight decrease during the hypothesized aridity event. We interpret warm-biased temperatures (with an average of 32.9°C) that do not vary significantly through the study section. Carbonate nodules are likely to have precipitated in highly evaporative conditions as indicated by the presence of dolomite. Utilizing a simple Rayleigh fractionation model and two estimates of δ 18 O of water, we suggest that evaporation of 2–57% is necessary to result in an enriched end member δ 18 O w . These data suggest that an increase in aridity is a result of lower MAP rates and greater evaporation during seasonal extremes. Lastly, revised p CO 2 calculations suggest overestimates but indicate a shift towards greater concentrations during the positive CIE.

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 Damage zones of different fault types are investigated in siliciclastics (Utah, USA), carbonates (Majella Mountain, Italy) and metamorphic rocks (western Norway). The study was conducted taking measurements of deformation features such as fractures and deformation bands on multiple 1D scanlines along fault walls. The resulting datasets are used to plot the frequency distribution of deformation features and to constrain the geometrical width of the damage zone for the studied faults. The damage-zone width of a single fault is constrained by identifying the changes in the slope of cumulative plots made on the frequency data. The cumulative plot further shows high deformation frequency by a steep slope (inner damage zone) and less deformation as a gentle slope (outer damage zone). Statistical distributions of displacement and damage-zone width and their relationship are improved, and show two-slope power-law distributions with a break point at c. 100 m displacement. Bleached sandstones in the studied siliciclastic rocks of Utah are associated with a higher frequency of deformation bands and a wider damage zone compared to the unbleached zone of similar lithology. Fault damage zones in the carbonate rocks of Majella are often host to open fractures (karst), demonstrating that they can also be conductive to fluid flow.