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Late Miocene speleothems show significant warming, temperate vegetation, and wildfires in Arctic Siberia
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-08-04)Climate driven northward boreal forest expansion into the tundra biome controlled by permafrost will play a major role in global emissions trajectories. Yet our limited understanding of the interplay between vegetation and permafrost makes predictions of changing boreal forest extent difficult. We analyse fossil pollen, stable carbon isotopes, and lignin and levoglucosan biomarkers from Tortonian ... -
Pre- and syn-orogenic sedimentation and volcanic activity in the internal domain of the southern Kaoko–Dom Feliciano–Gariep orogenic system
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-07-14)This work discusses the timing and sources for the pre- and syn-orogenic sedimentation in the southernmost internal domain of the Kaoko–Dom Feliciano–Gariep orogen. One sample from the Marmora Terrane (Gariep Belt, southern Namibia) yielded data suggesting a syn-orogenic origin, whereas data from two other samples suggest their pre-orogenic nature. Two volcanic rocks from the San Carlos Formation ... -
Ductile to Brittle Progression During Exhumation Controlled the Architecture of the Naukluft Nappe Complex, Namibia
(Journal article; Tidsskriftartikkel, 2025)Mountain belt architecture and evolution can be represented by frictional Coulomb wedges, a simplification that works well in the shallow deformation conditions of many foreland fold‐thrust belts. However, thin‐skinned fold‐thrust belts often occur in rocks that can deform ductily at low temperature. We demonstrate the importance of early ductile deformation in establishing the regional structure ... -
Decoupling short- and long-term methane seepage dynamics: high-resolution insights from Pyrgo spp. δ¹³C records at Woolsey Mound, Gulf of Mexico
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-07-24)Oceanic methane seepage plays a critical role in the global carbon cycle, yet reconstructing transient seepage variability remains challenging due to the complex interplay of environmental dynamics and biogeochemical processes. Here, we demonstrate that stable carbon isotopes from individual Miliolida foraminifera, particularly Pyrgo spp., offer a reliable high-resolution proxy for short-lived, ... -
Into the Blue: An ERC Synergy Grant Resolving Past Arctic Greenhouse Climate States
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-07-30)The Arctic Ocean is turning blue. Abrupt Arctic warming and amplification is driving rapid sea ice decline and irreversible deglaciation of Greenland. The already emerging, substantial consequences for the planet and society are intensifying and yet, model-based projections lack validatory consensus. To date, we cannot anticipate how a blue Arctic will respond to and amplify an increasingly warmer ... -
Deglaciation drove seawater infiltration and slowed submarine groundwater discharge
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-08-06)Submarine groundwater discharge—the flow of groundwater into the ocean—plays an important role in shaping coastal biogeochemical cycles. The absence of temporal constraints on offshore groundwater dynamics driven by proximal glacial loading hinders our assessment of how its circulation may vary in conceivable ice-free polar regions. Here we estimate residence times of saline groundwater at an active ... -
Diagenesis of hydrocarbon-seep carbonates: Common patterns, divergent pathways and conceptual pitfalls
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-07-04)Authigenic carbonates formed at marine hydrocarbon seeps are an important component of carbon cycling at continental margins. Ancient hydrocarbon-seep deposits serve as archives of the evolution of chemosynthesis-based ecosystems, past pore-water chemistry, and the tectonic architecture and geological history of their host sedimentary basins. However, while modern and ancient seep deposits share ... -
Western Greenland Ice Sheet-Land-Ocean Interactions: Near-Shore Dissolved Organic Carbon 14C Ages and Composition in Eastern Baffin Bay
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-07-11)Greenland's ongoing deglaciation and thawing permafrost, accompanied by an increase in ice sheet freshwater discharge and nutrient export, are significantly impacting the surrounding fjords and marine ecosystems. Understanding the geochemical linkages between ice, land, and marine environments is crucial for comprehending the effects of amplified cryosphere-biosphere interactions on marine ecosystems. ... -
Deep crustal deformation driven by reaction-induced weakening
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-07-11)Deep crustal shear zones, fundamental to the dynamics of terrestrial plate tectonics, exhibit complex processes of initiation and evolution that are yet to be comprehensively quantified across both long and short temporal scales. Conventionally, thermo–mechanical models posit that crustal rock behaviour is dominated by monomineralic aggregates undergoing processes like intracrystalline plastic ... -
Seasonal sea ice characterized the glacial Arctic-Atlantic gateway over the past 750,000 years
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-07-04)The past occurrence of an extreme ~1-kilometer–thick Arctic Ocean–Nordic Seas ice shelf has been inferred from submarine landscape features and geochemical records, although fundamental aspects of its characteristics, impacts, and timing remain highly debated. Here, we challenge this pan-Arctic glaciation hypothesis by investigating two sites from the Arctic-Atlantic gateway (AAG) and the Nordic ... -
Controls of sediment-bound and dissolved nutrient transport from a glacierised metasedimentary catchment in the high Arctic
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-06-16)Rapid warming in polar and alpine areas is causing significant glacier mass loss and resulting in increasing freshwater delivery to the oceans. Recent research indicates that higher meltwater water runoff is likely to increase solute and sediment transport, which will include nutrients, to downstream environments. This enhanced delivery may drive a negative feedback effect on atmospheric CO<sub>2</sub> ... -
Heavy potassium isotopes in carbonatites reveal oceanic crust subduction as the driver of deep carbon cycling
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-06-13)Carbon cycling between surface and mantle reservoirs is pivotal in fostering habitability of Earth. A critical yet poorly constrained parameter is whether crustal carbon can “survive” devolatilization processes that accompany slab subduction and therefore influence deep carbon budgets. Carbonatites provide a key record to address this important topic. Here, we present high-precision potassium isotope ... -
Geology of critical mineral deposits of the Kuljuktau Mts., Central Kyzylkum (Uzbekistan)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-12-19)This article presents characteristics of geological and tectonic structures of the Kuljuktau Mountains, mineralogical and geochemical features of its volcanic and intrusive rocks and associated mineralisation of critical elements. The Taskazgan graphite, Shaidaraz lithium, and Tozbulak high-purity quartz deposits, and new prospects for rare earth mineralisation have been identified as the most ... -
Planktic calcifiers: from living assemblages to proxies in the Arctic Ocean
(Conference object; Konferansebidrag, 2025)Planktic foraminifers, pteropods, and coccolithophores are marine calcifiers, organisms living in the water column and found throughout all oceans, with shells made of calcium carbonate. Because of their shell, they play an important role in the carbon cycle exporting calcium carbonate from the upper ocean to the sea floor when they die and sink. If no dissolution occurs on the water column or within ... -
Sedimentary ancient DNA insights into foraminiferal diversity near the grounding line in the western Ross Sea, Antarctica
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-06-06)Foraminifera are important marine environmental indicators widely used in paleoceanography and paleoclimate studies. They are a dominant component of meiobenthic communities around the Antarctic continental shelf, including rarely studied locations below the ice shelves, close to the grounding line. In this study, we use high-throughput sequencing of sedimentary ancient DNA (sedaDNA) targeting ... -
Origin and composition of hydrothermally-influenced sediments at Aurora Vent Field, southwestern Gakkel Ridge (82.9°N)
(Journal article; Tidsskriftartikkel, 2025-05-21)Slow–ultraslow spreading ridges represent half of the total length of the global mid-ocean ridge system and have been recognized to host hydrothermal activity. Their role as a source versus sink of elements in the oceans remains poorly constrained. Here, we present the first sediment data from the Aurora Vent Field (~3900 m depth) on the ultraslow spreading Gakkel mid-ocean ridge and the northernmost ... -
Antarctic glaciers export carbon-stabilised iron(II)-rich particles to the surface Southern Ocean
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-05-30)Iron is an essential micronutrient for phytoplankton and plays an integral role in the marine carbon cycle. The supply and bioavailability of iron are therefore important modulators of climate over glacial-interglacial cycles. Inputs of iron from the Antarctic continental shelf alleviate iron limitation in the Southern Ocean, driving hotspots of productivity. Glacial meltwater fluxes can deliver ... -
The Role of Ballasting, Seawater Viscosity and Oxygen-Dependent Remineralization for Export and Transfer Efficiencies in the Global Ocean
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-05-05)The particulate organic carbon (POC) flux from the euphotic zone to the deep ocean is central to the biological carbon pump. It is typically evaluated using “export efficiency” and “transfer efficiency,” which reflect POC formation and sinking and carbon sequestration efficiency in the ocean's interior, respectively. Since observations of these metrics are limited, biogeochemical models can elucidate ... -
Southern Ocean Carbon Export Revealed by Backscatter and Oxygen Measurements From BGC-Argo Floats
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-04-28)The Southern Ocean (south of 30°S) contributes significantly to global ocean carbon uptake through the solubility, physical and biological pumps. Many studies have estimated carbon export to the deep ocean, but very few have attempted a basin-scale perspective, or accounted for the sea-ice zone (SIZ). In this study, we use an extensive array of BGC-Argo floats to improve previous estimates of carbon ... -
Arctic fjord ecosystem adaptation to cryosphere meltdown over the past 14,000 years
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-04-25)The Arctic cryosphere is the epicentre of acute global change impact, with abrupt warming and amplification driving rapid sea ice decline and irreversible glacial ice loss. A key challenge is understanding how the cryosphere meltdown will impact Arctic marine carbon cycles and ecosystems. Here, we use organic geochemical biomarkers to trace the contribution of different planktonic groups to organic ...
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