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 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.

Abstract Interpretation of faulted reservoirs is hindered by an industry-wide lack of structural specialists, which in turn hinders the development of structurally proficient interpreters. This can have expensive consequences, including poor models of dynamic flow in reservoirs, erroneous calculations of reserves, and difficulties during well drilling. Focused training using paper maps, outcrop visits, and digital models of the same structures helps to introduce and reinforce concepts. The first component of the training is to provide participants with a set of two-dimensional seismic lines created from a geological model of a faulted reservoir. Participants must create a structure contour map containing faults that honor simple rules such as conservation of throw at fault intersections, identification of fault tips, consistent sense of offset and vergence along strike, and identification of fault relays. The second component is a visit to the outcrop from which the paper map was derived, providing the opportunity to discuss differences between faults in outcrop and faults as visible on seismic data. The final component provides participants with a digital model of the outcrop, giving them the opportunity to create a geologically valid interpretation that can be used for fault property prediction or reservoir model creation. This three-pronged training provides grounding in structural geology and lets interpreters know the rules that their fault framework models should obey. Applying these techniques during interpretation saves time by ensuring that “busts” are caught and fixed before they become institutionalized, and also closes the gap between the geophysicist/seismic interpreter and the geologist/static modeler.