ABSTRACT The Cretaceous-Paleocene (K/P) boundary intervals are rarely preserved in successions of shallow-water limestones. Here, we describe a shallow rocky shore on the active orogenic wedge of the eastern Alps (Austria) fringed by a carbonate platform that was largely cannibalized by erosion. We compared this succession with similar nearshore environments globally, as well as the deep sea, to gain a better understanding of the environmental response to the K/P boundary transition. In the eastern Alps, Cretaceous and Paleocene lithofacies across the K/P boundary transition are separated by a hardground that formed during subaerial exposure and that terminates Upper Maastrichtian limestone with planktic foraminiferal assemblages deposited at neritic depth during zone CF3 (ca. 66.500 Ma). Above the hardground, there are beachrocks with early Danian zone P1a(1) assemblages, which indicate the hardground spans about ~600 k.y. of nondeposition and/or erosion. During the early Danian, the marine transgressive fringe fluctuated between “shoreface to emersion” environments, depositing limestones rich in bryozoans, rhynchonellids, coralline algae, and rare planktic foraminifera along with abraded, bored, and/or encrusted clasts eroded from older rocks. Repeated short subaerial exposure is marked by vadose diagenesis and hardgrounds, including an ~1.5 m.y. interval between magnetochrons C29n to C28n and planktic foraminiferal zones P1b to P1c(2). Comparison with platform carbonate sequences from Croatia, Oman, Madagascar, Belize, and Guatemala, as well as nearshore siliciclastic environments of southern Tunisia, Texas, and Argentina, across the K/P boundary transition revealed surprisingly similar deposition and erosion patterns, with the latter correlative with sea-level falls and repeated subaerial exposure forming hardgrounds. Comparison with deep-sea depositional patterns revealed coeval but shorter intervals of erosion. This pattern shows a uniform response to the K/P boundary transition linked to climate and sea-level changes, whether in shallow nearshore or deep-sea environments, with climate change tied to Deccan volcanism in magnetochrons C29r-C29n.

ABSTRACT The Salem Limestone (Valmeyeran, Mississippian) is a preeminent dimensional limestone quarried in a two-county area of south-central Indiana for nearly 200 years. Advances in quarry technology in the past 30 years produce nearly smooth-sawn quarry walls that show the exquisite depositional details of the Salem carbonate shoal. The Salem shoal is part of a large-scale shoaling sequence that produced a carbonate platform during the middle Mississippian that began at the end of Borden Group (Mississippian) delta deposition and culminated with the deposition of the Ste. Genevieve Limestone (Mississippian). The Salem was deposited as a high-energy, but subtidal shoal above fair-weather wave base. Four environments are recognizable within the shoal: active shoal, open lagoon, intrashoal channel, and intershoal channel. A shoal crest environment may also be present as a fifth environment. A hierarchy of bounding surfaces can be defined using the sawed quarry exposures. First-order surfaces are foreset laminae and appear as inclined or horizontal stratification. Second-order surfaces are the contacts between similar bedforms, and third-order surfaces truncate first- and second-order surfaces, representing breaks in sedimentation. Combined they define mesoforms within the shoal complex. Fourth-order surfaces, similar to third-order surfaces, represent a change from a shoal to lagoonal setting. Evidence of hard-ground development occurs along third-order surfaces, associated with encrusting bryozoan holdfasts, corals, and columnar subtidal stromatolites. Tracing surfaces on the quarry walls is vital to reconstructing the internal architecture of the shoal and the processes that operated within it. We will examine this shoal architecture by visiting quarries and an outcrop, and we will visit a mill where quarried stone blocks are fabricated into panels and shapes for buildings.

Abstract Wintershall Noordzee BV recently discovered and appraised two Chalk oil fields (Rembrandt and Vermeer) in the Dutch North Sea with wells F17-10, F17-11, F17-12 and F17-13x. Extensive core material is available, and biostratigraphical analysis plus sedimentological evaluation results are presented here. Integration of these data with detailed 3D seismic interpretation results in interesting conclusions on the tectonic inversion of the Dutch Central Graben. It can be determined that the main inversion event is the Sub-Hercynian Phase, after which an island was formed in the Chalk sea during the Campanian and Maastrichtian. Around this island, erosion products can be found in the Chalk intervals. These sediments are time and facies comparable to the Vaals Formation in the south of The Netherlands, adjacent to the inverted Roer Valley Graben. Maastrichtian sediments are seen to onlap onto the island, decreasing it in size and influence as a sediment source. It is proposed that the Laramide inversion phase in the Dutch Central Graben is a period of non-deposition and, possibly, this is also the case for most of the other Dutch inverted basins.

ABSTRACT New data and review of classic sections from the Middle and Upper Ordovician North American Midcontinent in the Upper Mississippi Valley provide a refined picture of the age, stable isotope geochemistry, faunal composition, and—ultimately—origin of this epeiric ramp succession. Sequence stratigraphic analysis reveals a series of unconformity-bounded, genetically related facies packages. Shallowing and deepening trends are sometimes difficult to resolve due to a paucity of hydrodynamic indicators, yet unconformity surfaces are well marked by hardgrounds and confirmed by negative C-isotope spikes. Recent conodont biostratigraphy, new U-Pb radioisotopic ages for K-bentonites, and correlation of C-isotope profiles to global trends suggest that the succession spans the Darriwilian to Hirnantian epochs. Focus on Platteville to lower Galena Group strata (Sandbian to early Katian) provides a temporally high-resolution look at the onset and evolution of a long-term (>2 m.y.) positive carbon-isotope excursion, short-term perturbations in that record, and relationship to the preservation and diversity of the enclosed fauna and strata. Major changes in authigenic mineral suites and organic carbon content throughout the Upper Ordovician Upper Mississippi Valley suggest at least three major redox cycles. The combined evidence for globally recognized, positive carbon-isotope excursions coincident with these redox cycles, as well as high-frequency, sea-level fluctuations and successive faunal turnover events, suggests far-field responses to multiple global oceanic anoxic events.