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 Flake graphite is a critical battery material due to its role as the primary anode component in lithium-ion batteries. With the shift to electrification of vehicles, it is forecast that in the next five years flake graphite’s number-one use will be in battery applications, overtaking its traditional industrial uses. The burgeoning demand for battery anode materials is anticipated to double the current natural flake graphite market of roughly 645,000 tonnes per annum by 2025, which will require new flake graphite sources like the Molo graphite deposit to come into production. The Molo graphite deposit is world class due to its large size (NI 43–101 measured resource of 23.62 Mt at 6.32% C, indicated resource of 76.75 Mt at 6.25% C, and inferred resource of 40.91 Mt at 5.78% C), high proportion of large and jumbo flake (46.4%), and high average flake carbon purity (97.27% C). The deposit was discovered in 2011 as the result of a regional exploration program initiated by NextSource Materials Inc. following their delineation of a vanadium deposit called the Green Giant. Graphitic mineralization in the Molo is bimodally distributed, with low-grade and high-grade zones having carbon cutoff grades of 2 and 4% C, respectively. High-grade mineralization is associated with metamorphosed siltstones and mudstones, while low-grade mineralization is associated with rocks interpreted to represent metamorphosed sandstones, which are interpreted to be more favorable hosts for large- and jumbo-flake graphite. The Molo graphite deposit appears to have resulted from many mineralizing events, which extended over a period of time that may range from ca. 900 to ca. 490 Ma. These include graphitization during the emplacement of anorthosite complexes, graphitization in a high-strain regime under high-pressure and high-temperature granulite facies metamorphism during the collision of the Androyen domain with the Vohibory domain, graphite refining and recrystallization believed to have taken place during East Gondwana and West Gondwana collision, and the formation of postcollisional hydrothermal vein graphite during orogenic collapse. The superimposition of the tectono-metamorphic history of southern Madagascar on a sedimentary sequence in which the protoliths were rich in organic carbon has resulted in world-class flake graphite mineralization with high carbon purities and large flake sizes.