Bullslaughter Bay in southern Pembrokeshire, UK, exposes sections of Upper Mississippian limestone strata. In many places, the rock suffered an isovolumetric alteration during a period of sea-level oscillations. We used multiple approaches to study the weathered rocks, combining sedimentological, petrographic and isotopic compositions (δ18O and δ13C values). Two main microfacies are recognized: (i) packstones/grainstones, characteristic of an open marine shallow subtidal/intertidal environment, with a high degree of agitation, slightly elevated salinity and temporary subaerial exposure; and (ii) mudstones/wackestones in a lagoonal setting and intertidal or supratidal environments, with a pedogenetic influence. In both cases, a complex diagenetic story, which started early in a meteoric environment, induced a strong alteration producing loose sediments in place of the parent rock. Calcretization, at or near the sediment surface in the vadose zone, was one of the most widespread diagenetic modes. It could be associated with beachrocks. Carbon and oxygen stable isotope analyses from more or less weathered limestones support the petrographic data: they show non-marine values with δ13C ranges of from −2.13 ‰ to 1.75 ‰ and δ18O from −6.05 ‰ to −4.66 ‰. These values are systematically lower than those of the middle Carboniferous seawater. Some periods of low sea level and subaerial exposure allowed gypsum to form. Neoformation of euhedral quartz by probable replacement after sulfate, and halite pseudomorphs after gypsum in a hypersaline environment are documented for the first time in southern Pembrokeshire. The studied weathered limestones present a complex diagenetic evolution related to sea-level oscillations in a range of hot and contrasting seasonal climates.

The architecture of coastal sequences in tectonically-active regions results mostly from a combination of sea-level and land-level changes. The objective of this study is to unravel these signals by combining sequence stratigraphy and sedimentology of near-shore sedimentary sequences in wave-built terraces. We focus on Santa María Island at the south-central Chile margin, which hosts excellent exposures of coastal sediments from Marine Isotope Stage 3. A novel method based on statistical analysis of grain-size distributions coupled with facies descriptions provided a detailed account of transgressive–regressive cycles. Radiocarbon ages from paleosols constrain the chronology between > 53 and ~ 31 cal ka BP. Because the influence of glaciations can be neglected, we calculated relative sea-level curves by tying the onset of deposition on a bedrock abrasion platform to a global sea-level curve. The observed depositional cycles match those predicted for uplift rates between 1.2 and 1.8 m/ka. The studied sedimentary units represent depositional cycles that resulted in reoccupation events of an existing marine terrace. Our study demonstrates wave-built marine terrace deposits along clastic shorelines in temperate regions can be used to distinguish between tectonic uplift and climate-induced sea-level changes.