Early diagenesis of icehouse carbonate is complex, but can significantly modify depositional porosity and permeability. During icehouse times, high-amplitude highfrequency sea-level oscillations cause subaerial exposure, with vertical migration of meteoric hydrological-zones (vadose, fireshwater and mixing-zone) through the platform sediments. Repeated cycles of subaerial exposure and associated meteoric diagnesis result in significant porosity inversion, as carbonate grains are dissolved and re-precipitated as calcite cement. This diagenetic overprinting generates a complex pattern of cementation and secondary porosity and permeability, the distribution of which cannot be predicted simple through study of diagenetic products.

The Paleocene-Eocene Thermal Maximum (PETM), a period of abrupt and significant global warming, is one of the most dramatic climate events in the history of our planet. Long-term climatic change within the overall greenhouse climate of the Eariy Paleogene was also investigated. The Early Eocene Climatic Optimum (EECO) at 52 Ma marks what is believed to be a temperature maximum for the Paleogene.

During the Mesolithic the lakes and wetlands of central Ireland were a focus for hunter- gatherer activity. The extensive bogs and numerous lakes in the region represent a substantial palaeoenvironmental record. Five wetland sites were the subject of palaeoenvironmental investigation including palynology and mollusc analysis. These sites were selected based on their proximity to known Mesolithic locations. Particular attention was paid to disturbance of woodland cover. These investigations produced a record of regional vegetation and landscape change during the Mesolithic. Corylus-dominated woodland was present in the Midlands prior to the known arrival of Mesolithic groups, while to the south-west Pinus sylvestris was a greater component of the woodland. Openings in the woodland were identified throughout the period becoming more common in the later Mesolithic. Some instances of vegetation disturbance by fire appear to have promoted the expansion of Corylus suggesting possible Mesolithic manipulation of the landscape. However, Corylus does not seem to have always benefitted from openings in the woodland. Non-marine molluscs appear to have spread rapidly along the tributaries of the River Shannon during the early Holocene. Contemporary sediment from a more isolated lake revealed a more limited mollusc fauna.

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This study seeks to determine the extent to which chemostratigraphy can supplement other stratigraphic tools in determining the effects of climate change in loess-palaeosol sequences. Geochemical change has been used to illuminate the effects of glacial/interglacial climate change in Chinese loess-palaeosol sequences; less work has been done to examine the effects of stadial/interstadial climate change and little work has been carried out in Europe on either aspect. Two loess-palaeosol sites were selected in northwestern Europe that were known to provide good records of the last ice age. This study has produced detailed descriptions of variation in concentrations of the major, minor and rare-earth elements. These are compared with variation in the standard sedimentological parameters (grain size, organic carbon content and carbonate content) and in enviromagnetic characteristics, which are accepted as palaeoclimate proxies. The existing polymineral-based luminescence chronology at each site has been enhanced using a quartz-based approach,which broadly confirms the accuracy of previous ages and generates estimates of increased precision. That chronology facilitates comparison of these analyses with evidence for palaeoclimatic: change in the wider record, including GRIP ice-core data. Grain size is shown to be a strong proxy for variation in mean wind strength and in accumulation rates which can be correlated in detail with GRIP. The study has established that geochemical heterogeneity now apparent at the sites has been imposed by weathering. Carbonate weathering is a reliable indication of major pedogenic episodes but its detailed interpretation is tempered by carbonate mobility. Silicate weathering occurs at lower intensity than carbonate weathering but is a permanent record since silicates are not subject to reprecipitation under these conditions. The study concludes that chemostratigraphy is a climatological proxy, detecting periods of significant amelioration. It is not a replacement for conventional proxies, it complements them and provides additional evidence upon which climatic reconstructions can be made.

This study has specifically developed and applied new methodologies and successfully captured very high‐resolution palaeoenvironmental and palaeoclimatic data over a period ≤55 years in the Mid‐Devonian Orcadian Basin, Scotland. Analysis of 110 successive discrete laminae (55 varve sets) in a lacustrine sequence has produced the most detailed archive of environmental and climatic change through time ever from ancient sediments. Geological and geochemical data sets have captured intra‐annual (seasonal) variation in palaeoclimate and palaeoenvironment as well as short‐term cyclical change. Varve compositions (carbonate/clastic pairs) indicate a climate with substantial intra‐annual variation in rainfall. Cycles with an average periodicity of 12 years which have previously been attributed to sunspot solar forcing also show a shift in compositional dominance from allochthonous clastic material to authochthnonous carbonate precipitate over 12 years. This indicates that climatic wetness also varied cyclically. The abundance of specific biomarker compounds – particularly β,β‐carotane but also squalane and pristine/phytane coupled with elemental data (C/S) indicate that lake waters were hypersaline. Changes in the abundance and ratios of these salinity dependant proxies show that salinity varied seasonally as well as cyclically. Stable isotope data (δ13Ccarb / δ18Ocarb) show that temperature and primary productivity also varied on a seasonal and cyclical scale, while δ13Corg and the n‐alkane skew confirm that the organic carbon present was sourced predominantly from within‐lake algal sources at all timescales observed. The rate of carbon burial (MARcarbon) also exhibits cyclical variation. An antithetic relationship between δ18O–derived palaeotemperatures and a carbon burial efficiency parameter (forganic) at cycle scale shows that the fraction of organic carbon buried decreased as temperature increased.