Morgan Thomas Jones

Understanding ancient climate dynamics is crucial to accurately forecast future changes to Earth’s climate system. The Norwegian High-Arctic archipelago of Svalbard experiences higher-magnitude warming than the lower latitudes. Its sedimentary succession provides an important climate archive spanning much of the Phanerozoic, including several hyperthermal events and mass extinctions of global importance. These include the End-Permian Mass Extinction (EPME) and the Paleocene–Eocene Thermal Maximum (PETM). In addition, the High Arctic Large Igneous Province (HALIP) provides an opportunity to study how igneous sills interact with organic-rich shales to generate greenhouse gases during contact metamorphism. The ongoing multidisciplinary international project SvalCLIME aims to systematically study these hyperthermal events and their relationships to Phanerozoic climate evolution. SvalCLIME seeks to drill multiple shallow boreholes at four sites in Spitsbergen that will provide a semi-continuous record of Phanerozoic stratigraphy from an underexplored region. The drill cores, in conjunction with outcrops, will provide a Permian–Eocene climate record of unprecedented continuity. Here, we synthesise existing pre-Quaternary Phanerozoic (540–2.58 Ma) paleoclimate and paleoenvironmental data from Svalbard in curated data packages to complement a recently published comprehensive review article. The data packages are organised by proxy, facilitating the addition of future data sets. We present composite data coverage plots of key proxies (stable carbon isotopes [δ13C], oxygen isotopes [δ18O], pyrolysis, mercury) that illustrate data availability and current data gaps. Further, we give an overview of available geochronological constraints for Svalbard’s pre-Quaternary Phanerozoic rock record, likewise curated into two data collections of 1) various methods that provide age constraints and 2) biostratigraphy. We also discuss the integration of various data sets in four case studies to illustrate the benefit of compiling such data for both drill cores (Longyearbyen CO2 lab and Deltadalen) and outcrops (Festningen, Lusitaniadalen, Munindalen and Billefjorden).

The Paleocene–Eocene Thermal Maximum (PETM; ∼55.9 Ma) was a rapid global warming event marked by intensified hydrological cycling, enhanced continental weathering, and widespread ocean deoxygenation. Although the extent of anoxic basins during the PETM is relatively well documented, the contribution of high‐latitude continental weathering to regional ocean redox dynamics remains unclear, leaving the spatial impact of weathering on ocean biogeochemistry poorly constrained. Here, we use elemental geochemical data from sediments recovered from the Vøring Basin, North Atlantic during International Ocean Discovery Program (IODP) Expedition 396, to reconstruct variations in continental weathering intensity and redox conditions across the PETM. Our results show that high accumulation rates during the PETM coincided with low chemical weathering relative to underlying pre‐PETM strata, indicating that rapid burial limited chemical alteration, although accumulation rates in the pre‐PETM interval are not well constrained. This pattern likely reflects intensified rainfall, which primarily enhanced physical erosion and delivered large amounts of detrital material to the basin while limiting chemical weathering. The influx of fresh, reactive detrital material from the North Atlantic Igneous Province (NAIP) increased the supply of bioavailable nutrients, likely stimulating elevated primary productivity and contributing to the development of euxinic bottom waters during the onset of the PETM. On the boreal mid‐Norwegian margin, our data suggest that enhanced physical erosion, rather than chemical weathering, dominated continental responses to extreme greenhouse forcing, promoting nutrient enrichment, transient euxinia, and organic carbon burial.

Hydrothermal vent complexes are degassing structures that form in response to rapid volatile generation and release associated with igneous sill intrusions in sedimentary basins. They are discovered in numerous basins worldwide, originating from sills and contact aureoles and terminating at the paleosurface where they form up to 10 km wide craters. Field studies and numerical models have suggested that the venting processes were explosive, releasing aureole-derived gases, sedimentary pore fluids, and fragmented sedimentary rocks to the seafloor or land surface. However, ejecta deposits originating from hydrothermal vent complexes are poorly studied and hard to identify, hampering detailed reconstructions of vent formation and evolution. Here we report the characteristics of a possible ejecta deposit from Vøring Basin Hole U1570D drilled as part of IODP Expedition 396 in 2021. During core logging, an unusual layer was identified immediately overlaying the top Paleocene strata. This layer is about 2m thick, contains Apectodinium augustum dinocysts restricted to the Paleocene Eocene Thermal Maximum (PETM), and also yields abundant reworked Paleocene and Cretaceous microfossils. Moreover, the layer is characterized by rounded fragments of claystone, angular chert and quartz fragments, dolerite fragments, fresh and devitrified volcanic tephra, and a mixed groundmass of smectite-illite with diatoms and early diagenetic pyrite. Electron microprobe analyses document a bimodal tephra geochemistry, with both basaltic and rhyolitic compositions and morphologies indicating no or minor reworking. In the presentation we will discuss two possible formation scenarios for the layer, including 1) erosion from nearby marginal highs, and 2) ejecta deposit sourced from an explosive submarine eruption from a hydrothermal vent complex, mobilizing Cretaceous and Paleocene strata from the conduit zone. In any case, the bimodal tephra composition stresses the presence of an evolved igneous system in the Vøring Basin during the PETM, with a potential genetic link to a recently discovered Paleocene granite.

The response of the climate system to rapid carbon-cycle perturbations can be constrained by studying past transient climate events such as the Paleocene–Eocene Thermal Maximum (PETM, ~56 million years ago). The PETM is marked by a massive input of isotopically light carbon, as recorded by a 3–4‰ negative carbon isotope excursion (CIE) in sedimentary records globally. Estimates of the duration of the rapid onset of the CIE range from a few hundred to several thousand years. The exact duration remains poorly constrained due to the scarcity of marine sedimentary records that 1) have sufficiently high sedimentation rates to resolve rapid decadal- to centennial scale transitions, 2) provide robust controls on sedimentation rates and event timing, and 3) preserve proxy data that record perturbations of the dissolved inorganic carbon (DIC) pool. Consequently, the rate of carbon release during the CIE onset, and its relevance for understanding anthropogenic climate change, remains unclear.International Ocean Discovery Program (IODP) Expedition 396 recovered expanded PETM successions on the Norwegian Margin, including a microlaminated CIE onset interval that preserves decadal-scale variability. We document the first occurrence of haptophyte alkenones from the onset of the PETM CIE and present a high-resolution record of their stable carbon isotopic variability (δ¹³Calk) across the onset interval. The δ¹³Calk records variations in the (isotopic) composition and concentration of the dissolved inorganic carbon (DIC) pool. We show that the δ¹³Calk record is not strongly influenced by local (volcanically induced) input of ¹³C-depleted carbon based on high-resolution sedimentary mercury and polyaromatic hydrocarbon data from this interval. Finally, we provide robust age control from the diatom laminations, enabling a direct and well-constrained estimate of the duration of the global CIE onset interval.

Reconstructions of ocean temperature through deep time frequently rely on isotopic or elemental compositions biotic carbonates (e.g. foraminifera, coccolithophores, molluscs, brachiopods). But what can be done when fossil carbonate is absent? Several high-latitude early Cenozoic and Mesozoic sites (e.g. Svalbard, Denmark) are characterized by an early dissolution of such biotic carbonates, with rapid reprecipitation of the CaCO3 as diagenetic carbonates, such as ikaite, calcite concretions, and interstitial calcite. Can these be of use in reconstructing palaeotemperature or paleoenvironmental conditions? What exactly do these carbonates represent? We investigate their age relative to their host sediment, and whether the pore waters they formed in could be considered to reflect ocean bottom-waters. We also look at possible kinetic biases and elemental fractionation during their formation, and if we can apply temperature proxies such as Mg/Ca ratios, stable oxygen isotopes, and/or clumped isotope thermometry.

Portable and core-scanning X-ray fluorescence (XRF) instruments have become increasingly utilized in making rapid, non-destructive chemical characterizations with high spatial resolution on a range of materials. Since basaltic cores are often highly fractured and uneven, portable XRF (pXRF) is preferred to conduct discrete chemical analyses. However, in this case, the user must select the location for each analysis, which can lead to biased datasets. Alternatively, XRF core-scanning (XRF-cs) instruments take a series of measurements along a section of core, increasing the number of analyses and, therefore, eliminating some of the bias introduced by discrete analyses conducted with a pXRF. The XRF-cs does, however, still require a flat sampling surface along the core that does not include void spaces, making rigid, vesicular, and often cracked basalts suboptimal targets. We collected 797 XRF-cs measurements on three basaltic cores collected during the International Ocean Discovery Program Expedition 396 to evaluate how effectively an XRF core scanner can build large, chemically representative datasets. We developed a method for filtering XRF-cs measurements and calibrated the data using discrete calibrated pXRF analyses and compared the XRF-cs data to pXRF and conventional bulk-rock data using various immobile (e.g., Al, Ti, Zr, Ni, Mn, Zn) and mobile (e.g., K, Ca, Sr) elements. The comparison between datasets shows that (1) the XRF-cs data reproduce trends observed by pXRF and conventional bulk-rock data at both the regional scale and the core scale, and (2) in some cases, the higher spatial resolution of the XRF-cs data reveals geochemical variations that are otherwise obscured using discrete analyses. The workflow outlined by this study can be used to select samples for future studies by efficiently providing reliable geochemical data for characterizing new and legacy hard-rock cores.

The Paleocene–Eocene Thermal Maximum (PETM; 55.9 million years ago) was a rapid, CO2-driven climate polycrisis, with global warming of 5-6°C1,2, ocean acidification3-5, and deoxygenation6-8. These stresses may have affected marine nitrogen cycling, particularly nitrification—a major source of nitrous oxide (N2O) 9 that remains underexplored on geological timescales. By integrating proxy records with Earth System modeling, we show that nitrification globally increased by ~56% during the PETM. Inhibiting effects of ocean deoxygenation10 and acidification11 on nitrification were outweighed by increased ammonium supply and nitrifier niche expansion. Enhanced nitrification led to a ~290% increase in total marine N2O production, contributing 0.3-1.4℃ of warming during the PETM. Our results highlight a strong, positive climatic feedback from nitrogen cycle perturbations under extreme global warming, ocean deoxygenation and acidification.

The area now known as the Barents Shelf region was strongly impacted by the End-Permian Mass Extinction and a fundamental reorganisation of source-to-sink systems along the northern margin of Pangaea. Here we integrate new sedimentological, ichnological, chemostratigraphic, and provenance data from western Spitsbergen, collected at Festningen, Reinodden, and the Sørkapp-Hornsund High (Hornsundneset, southern Spitsbergen), to reconstruct the timing and drivers of Early Triassic basin evolution. At Festningen and Reinodden, the sharp but conformable transition from Permian spiculitic Kapp Starostin Formation strata to siliciclastic mudstones and sandstones of the Lower Triassic Vardebukta Formation coincides with the onset of the negative δ13Corg excursion. The Vardebukta Formation preserves seven stacked transgressive–regressive packages within an Induan-age interval of ca 1.2 to 1.6 Myr. Individual cycle durations (ca 177 to 225 kyr) are incompatible with a single dominant Milankovitch component and instead suggest bundling of orbital frequencies and/or strong autogenic modulation of accommodation and sediment supply. On the Sørkapp-Hornsund High, a 75 Myr hiatus above Mississippian continental deposits is terminated by a 10 to 15 cm thick bentonitic tephra bed linked to the Siberian Traps Large Igneous Province. This is overlain by Induan-age polymictic alluvial-fan and ephemeral braided-river conglomerates (Brevassfjellet Beds), on which limited but recurrent vegetation cover developed. Detrital-zircon age spectra from the conglomerates closely match published data from the Vardebukta Formation at Festningen and the Induan-age Parish Bjerg Formation in Greenland, indicating a shared north Greenland Caledonian source and direct sediment routing during the latest Permian and earliest Triassic. These continental conglomerates are capped by fossiliferous shallow-marine limestones of Dienerian age, which are then overlain by the coarsening-upward shelfal succession of the Vardbukta Formation. The timing of Dienerian flooding of the Sørkapp-Hornsund High is not aligned with any individual transgressive-regressive package in the Vardebukta Formation, implying that local tectonic subsidence of a promontory-like high, rather than eustatic rise, governed its transgression. This research refines the palaeogeographical and tectonostratigraphical evolution of the northern margin of Pangaea during the latest Permian and earliest Triassic.

Sedimentary rocks can provide information about the Earth paleoenvironment and are studied extensively to understand the causes and consequences of global climate changes in deep time. They facilitate long-time perspectives that constrain climate models and provide analogues for how Earth systems may respond to, and recover from, intervals of profound environmental change, including projected anthropogenic change. The Norwegian Svalbard archipelago offers an extensive Phanerozoic stratigraphic record that reflects the geological evolution of the northern flanks of continental assemblages that include Laurentia, Eurasia, and Pangea. Svalbard's Phanerozoic sedimentary and paleoclimatic archive is controlled largely by Svalbard's overall northward plate-tectonic motion from equatorial to high latitudes but also by regional to local formation of topography and basins in response to long-term plate reorganization, as well as the near- and far-field influence of large igneous province activity on the tectono-stratigraphic and paleoclimatic development. Various sedimentary and geochemical proxies, such as bentonite beds and carbon isotope excursions associated with the far-reaching environmental effects of the Siberian Traps, the High Arctic Large Igneous Province, and the North Atlantic Igneous Province, are present in Svalbard's near complete geological record. As such, Svalbard is unique in that these and numerous other global environmental perturbations are recorded within a relatively restricted study area, with most of the key events preserved and recorded in easily accessible drill cores and well-exposed outcrop sections. Here we review deep-time paleoenvironmental and paleoclimate research in Svalbard by summarizing 148 peer-reviewed scientific articles. The review builds on the well-established tectono-stratigraphic and lithostratigraphic framework, as well as state-of-the art environmental reconstructions, to provide insights into the Earth system during the Phanerozoic northward drift of Svalbard and the many major biotic crises in the geological past. We focus on globally significant events including (i) the expansion of Devonian vegetation, (ii) the Carboniferous–Permian response to icehouse conditions during the Late Paleozoic Ice Age (LPIA), (iii) the End-Permian Mass Extinction (EPME) and the subsequent Triassic recovery, the (iv) Carnian Pluvial Episode, (v) Jurassic–Early Cretaceous climate perturbations including the Volgian Isotopic Carbon Excursion (VOICE) and the Aptian Ocean Anoxic Event 1a (OAE1a), and (vi) the Paleocene–Eocene Thermal Maximum (PETM). We present and synthesize existing core and outcrop data that preserve biological and geochemical proxies and climate-sensitive sedimentary facies that reflect environmental change in terrestrial and marine settings. Finally, we discuss the Phanerozoic climate recorded in Svalbard and its role in providing high-latitude calibration points for several global paleoclimate events to provide a higher-latitude perspective to complement the dominance of mid- and low-latitude locations and datasets in the literature.