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Abstract Most oceanic lead (Pb) is from anthropogenic emissions into the atmosphere deposited into surface waters, mostly during the past two centuries. The space‐ and time‐dependent emission patterns of anthropogenic Pb (and its isotope ratios) constitute a global geochemical experiment providing information on advective, mixing, chemical, and particle flux processes redistributing Pb within the ocean. Pb shares aspects of its behavior with other elements, for example, atmospheric input, dust solubilization, biological uptake, and reversible exchange between dissolved and adsorbed Pb on sinking particles. The evolving distributions allow us to see signals hidden in steady‐state tracer distributions. The global anthropogenic Pb emission experiment serves as a tool to understand oceanic trace element dynamics. We obtained a high‐resolution (5° station spacing) depth transect of dissolved Pb concentrations and Pb isotopes from Alaska (55°N) to just north of Tahiti (20°S) near 152°W longitude. The sections reveal distinct sources of Pb (American, Australian, and Chinese), transport of Australian style Pb to the water mass formation region of Sub‐Antarctic Mode Water which is advected northward, columnar Pb isotope contours due to reversible particle exchange on sinking particles from high‐productivity particle veils, and a gradient of high northern deep water [Pb] to low southern deep water [Pb] that is created by reversible exchange release of Pb from sinking particles carrying predominantly northern hemisphere Pb.²⁰⁸Pb/²⁰⁶Pb versus²⁰⁶Pb/²⁰⁷Pb isotope relationships show that most oceanic Pb in the North Pacific is from Chinese and American sources, whereas Pb in the South Pacific is from Australian and American sources. 

The Permian witnessed some of the most profound climatic, biotic, and tectonic events in Earth’s history. Global orogeny leading to the assembly of Pangea culminated by middle Permian time, and included multiple orogenic belts in the equatorial Central Pangean Mountains, from the Variscan-Hercynian system in the East to the Ancestral Rocky Mountains in the West. Earth’s penultimate global icehouse peaked in early Permian time, transitioning to full greenhouse conditions by late Permian time, constituting the only example of icehouse collapse on a fully vegetated Earth. The Late Paleozoic Ice Age was the longest and most intense glaciation of the Phanerozoic. Reconstructions of atmospheric composition in the Permian record the lowest CO2 and highest O2 levels of the Phanerozoic, with average CO2 levels comparable to the Quaternary, rapidly warming climate. Fundamental shifts occurred in atmospheric circulation: a global megamonsoon developed, and the tropics became anomalously arid with time. Extreme environments are well documented in the form of voluminous dust deposits, acid-saline lakes and groundwaters, extreme continental temperatures and aridity, and major shifts in biodiversity, ultimately culminating in the largest extinction of Earth history at the Permian-Triassic boundary.The Deep Dust project seeks to elucidate paleoclimatic conditions and forcings through the Permian at temporal scales ranging from millennia to Milankovitch cycles and beyond by acquiring continuous core in continental lowlands known to harbor stratigraphically complete records dominated by loess and lacustrine strata. Our initial site is in the midcontinental U.S.— the Anadarko Basin (Oklahoma), which harbors a complete continental Permian section from western equatorial Pangaea. We will also address the nature and character of the modern and fossil microbial biosphere, the chemistry of saline lake waters and groundwaters, Mars-analog conditions, and exhumation histories of source regions. Importantly, data from Deep Dust will be integrated with Earth-system modelling. This is crucial for putting the (necessarily local) drill core data into the broader global context and for understanding relevant mechanisms and feedbacks of the Permian Earth system. 

Abstract The Campanian Two Medicine Formation of northwestern Montana, USA, is richly fossiliferous, and discoveries made within the unit over the past century have greatly advanced our appreciation of dinosaur paleobiology and evolution. Previously undifferentiated from a lithostratigraphic perspective, the formation is now subdivided into four new members that include (from base to top) (1) the Rock City Member, (2) the Shields Crossing Member, (3) the Hagans Crossing Member, and (4) the Flag Butte Member. These new formal units and their associated fossil occurrences are also now included in an age model founded on eight high-resolution chemical abrasion–isotope dilution–thermal ionization mass spectrometry (CA-ID-TIMS) U-Pb ages. New age data confirm that the Two Medicine Formation accumulated during much of the Campanian, with deposition spanning ca. 82.4 Ma to 74.4 Ma. New age data further indicate that a major reorganization of depositional systems, marked by a shift from predominantly lacustrine to alluvial facies and accompanied by a dramatic increase in accommodation, transpired near the base of the new Flag Butte Member at ca. 76.3 Ma. This change in depositional regime correlates in age with the Judith River–Belly River discontinuity, which marks the contact between the McClelland Ferry and Coal Ridge Members in the Judith River Formation and coincides with the onset of the Bearpaw transgression in north-central Montana. The new lithostratigraphic and chronostratigraphic framework for the Two Medicine Formation serves to contextualize and calibrate the formation’s rich dinosaur fossil record, which can now be interrogated with increased clarity and precision. These results also provide ground truth for numerical models that explore the structure of the fossil record in relation to alluvial architecture and terrestrial sequence stratigraphy. 

Terrestrial strata of the Judith River−Belly River wedge, widely exposed in the plains of north-central Montana, southern Alberta, and southwestern Saskatchewan, were pivotal in early stratigraphic investigations of the Western Interior of North America and are renowned to this day for their spectacular preservation of Late Cretaceous fossils, most notably dinosaurs. Correlation of the Judith River Formation in Montana with the Foremost, Oldman, and Dinosaur Park Formations (= Belly River Group) in Canada has been challenging for a variety of reasons, including lithostratigraphic complexities, legacy bentonite ages of limited comparability, and distinctly different stratigraphic models on opposite sides of the international border. An updated model calibrated with U-Pb zircon ages provides an improved framework for stratigraphic analysis. New geochronology indicates that the Oldman−Dinosaur Park discontinuity in Dinosaur Provincial Park correlates in age with the mid-Judith discontinuity in the Judith River Formation in Montana, which is interpreted as an expansion surface linked to a major pulse of accommodation and onset of the Bearpaw transgression at ca. 76.3 Ma. The regionally expressed shift in alluvial facies marking the mid-Judith discontinuity can be traced in well logs from Montana to southern Canada, where it loses distinction and transitions to a subsurface signature typical of the Oldman−Dinosaur Park discontinuity, which in turn can be traced north to Dinosaur Provincial Park and beyond. Across this expanse, both discontinuities parallel the Eagle/Milk River shoulder at approximately the same stratigraphic height, confirming their chronostratigraphic significance. These findings have clear implications for regional correlation and the evolution of alluvial depositional systems in a foreland basin setting, and they afford an opportunity to evaluate existing interpretations and advance understanding of the stratigraphy and paleontology of the Judith River−Belly River wedge. The term “Judith River−Belly River discontinuity” should be used henceforth to refer to the chronostratigraphically significant stratal discontinuity that subdivides the Judith River−Belly River wedge throughout the plains of north-central Montana, southern Alberta, and southwestern Saskatchewan. 

Abstract The spectacular fossil fauna and flora preserved in the Upper Cretaceous terrestrial strata of North America’s Western Interior Basin record an exceptional peak in the diversification of fossil vertebrates in the Campanian, which has been termed the ‘zenith of dinosaur diversity’. The wide latitudinal distribution of rocks and fossils that represent this episode, spanning from northern Mexico to the northern slopes of Alaska, provides a unique opportunity to gain insights into dinosaur paleoecology and to address outstanding questions regarding faunal provinciality in connection to paleogeography and climate. Whereas reliable basin-wide correlations are fundamental to investigations of this sort, three decades of radioisotope geochronology of various vintages and limited compatibility has complicated correlation of distant fossil-bearing successions and given rise to contradictory paleobiogeographic and evolutionary hypotheses. Here we present new U–Pb geochronology by the CA-ID-TIMS method for 16 stratigraphically well constrained bentonite beds, ranging in age from 82.419 ± 0.074 Ma to 73.496 ± 0.039 Ma (2σ internal uncertainties), and the resulting Bayesian age models for six key fossil-bearing formations over a 1600 km latitudinal distance from northwest New Mexico, USA to southern Alberta, Canada. Our high-resolution chronostratigraphic framework for the upper Campanian of the Western Interior Basin reveals that despite their contrasting depositional settings and basin evolution histories, significant age overlap exists between the main fossil-bearing intervals of the Kaiparowits Formation (southern Utah), Judith River Formation (central Montana), Two Medicine Formation (western Montana) and Dinosaur Park Formation (southern Alberta). Pending more extensive paleontologic collecting that would allow more rigorous faunal analyses, our results support a first-order connection between paleoecologic and fossil diversities and help overcome the chronostratigraphic ambiguities that have impeded the testing of proposed models of latitudinal provinciality of dinosaur taxa during the Campanian. 

Abstract U-Pb geochronology by isotope dilution–thermal ionization mass spectrometry (ID-TIMS) has the potential to be the most precise and accurate of the deep time chronometers, especially when applied to high-U minerals such as zircon. Continued analytical improvements have made this technique capable of regularly achieving better than 0.1% precision and accuracy of dates from commonly occurring high-U minerals across a wide range of geological ages and settings. To help maximize the long-term utility of published results, we present and discuss some recommendations for reporting ID-TIMS U-Pb geochronological data and associated metadata in accordance with accepted principles of data management. Further, given that the accuracy of reported ages typically depends on the interpretation applied to a set of individual dates, we discuss strategies for data interpretation. We anticipate that this paper will serve as an instructive guide for geologists who are publishing ID-TIMS U-Pb data, for laboratories generating the data, the wider geoscience community who use such data, and also editors of journals who wish to be informed about community standards. Combined, our recommendations should increase the utility, veracity, versatility, and “half-life” of ID-TIMS U-Pb geochronological data.