Abstract. The >1000 km long Eurekan Belt is the northernmost mountain belt on Earth and formed as an intraplate orogen in response to Cenozoic plate reorganization of the North Atlantic–Arctic region. Eurekan deformation is well documented on Ellesmere Island, North Greenland and Svalbard. In North Greenland, the general orientation of the Eurekan Belt changes. The kinematic and temporal relationships between the differently trending fault systems of North Greenland remain poorly constrained. This study aims to explore the relationship between the major fault systems of North Greenland by providing a temporal framework for their kinematics. We present new low-temperature thermochronological data, including the first apatite (U-Th)/He ages from North Greenland, complemented by apatite fission track analyses and apatite U–Pb dating of mafic dykes. Thermal history models indicate a short-lived heating period during the latest Cretaceous (~70–65 Ma), with temperatures exceeding 120 °C, likely associated with a Late Cretaceous basin along the margin of North Greenland. The models imply repeated reactivation of the Kap Cannon Thrust Zone, the Harder Fjord Fault Zone and the Trolle Land Fault System during the Palaeocene, early and mid-Eocene, and Oligocene. The differently oriented fault systems constitute a coherent system, interpreted as part of the De Geer Fracture Zone, that was repeatedly reactivated under changing stress fields. The exhumation episodes of North Greenland were synchronous with those of adjacent regions of the Eurekan Belt. Oligocene exhumation of North Greenland can be linked to tectonic reorganization of the northern North Atlantic and the opening of the Proto-Fram Strait, which likely developed along pre-existing structural weaknesses. Together, these findings highlight the role of structural inheritance, thermal weakening, and fault reactivation in intraplate orogeny and provide temporal constraints on the tectonic and topographic evolution of the Arctic relevant to paleogeographic and high-latitude environmental reconstructions.

The modern Arctic has been formed through a series of continent-continent collisions, accretion of terranes and phases of crustal extension. The Neoproterozoic Timanian, Paleozoic Caledonian and Uralian, and late Mesozoic Verkhoyansk-Kolyma, Chukotkan and Brookian orogenies formed several large fold-and-thrust belts (FTBs). The FTBs are exposed across vast areas of continents and continue offshore to form a complex tectonic basement for thick sedimentary basins, playing an important role in the history of accumulation and deformation of younger unmetamorphosed sedimentary successions that are the subject of this volume. Recognition of the importance of FTBs in the Arctic geological history and their role as a controlling factor of development of Arctic sedimentary basins resulted in this chapter, in which we review the current state-of-knowledge about Arctic FTBs and highlight questions that remain to be addressed. The Enclosure D, a Map showing boundaries of the FTB and their internal first-order structural fabric, is a part of the overview.

Abstract We investigated highly mature sedimentary rocks exposed along both sides of the Fram Strait in the northern North Atlantic using apatite fission track and (U‐Th)/He thermochronology to obtain information on the thermal imprint of rifting and continental breakup processes along a sheared margin. Our data showed that the conjugate margins experienced several heating episodes, which we explain as resulting from heat transfer along segments of the De Geer Fracture Zone, a large continental transform system which connected magmatic centers north and south of the Fram Strait. Heating occurred prior to and during the Eurekan intraplate orogeny, which occupied the position of the present‐day Fram Strait during the Eocene. Heat transfer may have caused or contributed to lithospheric weak zones, which focussed deformation during intraplate orogeny. Movements along the transform fault system continued during the Oligocene, after the end of the Eurekan Orogeny, causing further structural weakening of pre‐existing fault zones. These were exploited during the final continental breakup leading to the opening of the Fram Strait. No unambiguous thermal signature associated with this latest stage of breakup was detected. Our data underline recent studies on the importance of structural inheritance and continental transform faults for the prolonged and complex processes of continental rifting and breakup.

Svalbard has long been thought to represent the easternmost realm of the Ellesmerian Orogeny in the late Devonian or early Mississippian (Svalbardian tectonic event). Several authors do not agree and present alternative interpretations of the observed structures in older and more recent articles. This article discusses a number of issues that, in our opinion, are not sufficiently considered in those works, but which are essential for the understanding of the Svalbardian tectonic event: (1) the possibility of re-deposited palynomorphs in the discussion of the deformational ages, (2) the age and structural setting of the crucial Adriabukta Formation in southern Spitsbergen, and (3) the presence and nature of the Svalbardian angular unconformity in central and southern Spitsbergen.

Tectonic models for development of the Svalbard Caledonides depend on reliable assessment of the metamorphic evolution of the various basement provinces involved. The Mosselhalvoya Group (MG) and the Atomfjella Complex (AC) have previously been assigned to the Nordaustlandet andWest Ny-Friesland terranes, respectively. New analytical data and petrographic observations indicate that both units experienced two-stage metamorphism under similar pressure-temperature (P-T) conditions. Two stages of amphibolite facies metamorphism (M1 and M2) are clearly recorded by garnet and staurolite porphyroblast textures. The results of thermodynamic phase equilibrium modeling indicate that peak M2 metamorphism occurred at similar to 7-7.5 kbar and 590-600 degrees C in both units. Zirconium-in-rutile trace element thermometry confirms the temperature estimates for M1 and M2 stages of metamorphism. Monazite chemical Th-U-Pb dates from the MG resolve a two-stage garnet growth at 444 +/- 7 Ma (M1) and 423 +/- 6 Ma (M2). In contrast, monazite dated in the AC defines a single age of 420 +/- 4 Ma interpreted as M2 growth. We suggest M2 was coeval with early strike-slip motion along the Billefjorden Fault Zone, whereas M1 reflects initial tectonic burial of the studied units. The similarity in metamorphic history between the both units suggests that the boundary between them is a subordinate thrust fault within the Atomfjella thrust stack rather than a major boundary separating the Nordaustlandet and West Ny-Friesland terranes. The MG should be included within the West Ny-Friesland terrane and the tectonic boundary with the Nordaustlandet terrane is likely the Eolussletta Shear Zone.

Here we show preliminary cave monitoring and speleothem results from Erdmannshöhle in Hasel, one of the oldest show caves in Germany. The comprehensive monitoring programme of drip water and cave air started in late summer 2022 and is still ongoing. In addition, we present precise 230Th/U, petrography, and proxy data from several speleothems. Cave temperature and relative humidity loggers show constant values of 10.7 +- 0.5 °C and 100.0% humidity. First results of the cave air CO2 mapping show a strong seasonal ventilation pattern with summer values reaching >6000 ppmV. During winter time, CO2 drops to values < 1700 ppmV, favoring carbonate precipitation during the cold season. Drip water is collected bi-monthly from 10 drip sites located in three chambers of the second horizontal cave level where speleothem growth is still active. First data of drip water stable isotope values agree with the local meteoric water line. In addition, abundances of dissolved minor and trace elements such as Mg, Ba, Sr, K, and Na, as well as anions (e.g., Cl, NO3, PO4, SO4) are analyzed. The data will be compared to the recently precipitated carbonate collected on watch glasses which are mounted on top of drip rate loggers.230Th/U dating of speleothems from Erdmannshöhle is promising due to relatively high U contents in the range of 0.05 - 1 µg/g, and low detrital Th contamination. Analysis of drill cores from 25 stalagmites and flowstones from different cave chambers and cave levels extend the preliminary survey of Becker et al. (2020). The data shows that speleothem growth was active in Erdmannshöhle at least for the last 162 ka (Becker et al. 2020), in particular during past warm interglacial periods and the Holocene. Preliminary exploration of proxy data from two speleothems covering several parts of the Holocene demonstrate the high potential of Central European paleoclimate reconstruction. Stable oxygen records suggest a strong link to North Atlantic climate variability. In addition, carbon isotope and high resolution laser ablation ICPMS trace element records are explored for their paleoclimatic significance.In summary, Erdmannshöhle has excellent preconditions for the continuous reconstruction of past Central European climate, and this comprehensive monitoring effort will provide an important step towards interpreting speleothem proxy data. ReferenceBecker, A., Piepjohn, K., & Schröder-Ritzrau, A. (2020). The Erdmannshöhle near Hasel, SW Germany: karst environment and cave evolution. Swiss Journal of Geosciences, 113(1), 1-25.

Outcrops with conspicuous reddish to yellow-colored clinker, blackish paralava, and blends of both with a breccia-like appearance occur across the Canadian Arctic. We examined such rocks on Ellesmere Island, Banks Island, and the Mackenzie Delta area. These rocks are a product from natural combustion of bituminous shale and low-rank coal seams in Cretaceous and Paleogene host sedimentary rocks, respectively. The main mineral phases of clinker and silicate paralava samples are comprised of quartz + hematite ± feldspars ± cristobalite (or tridymite) ± cordierite–sekaninaite ± clinopyroxene ± sillimanite ± glass. Slag-like iron oxide paralava (74–95 wt.% total Fe 2 O 3 ) consisting of hematite ± magnetite ± clinopyroxene occur in Paleogene host sedimentary rocks, rich in siderite concretions. The whole-rock geochemical composition of clinker and silicate paralava shows similarities for samples from the same outcrop. Regional and local specific elemental enrichments are mainly inherited from the sedimentary protoliths, which are characterized by volcanogenic input (Paleocene sedimentary rocks) or oxygen-depleted depositional conditions (Upper Cretaceous bituminous sedimentary rocks). Spontaneous combustion could take place when the organic-rich sedimentary rocks become exposed to atmospheric oxygen. This process has occurred at least since the Messinian stage (Miocene) on Ellesmere Island (6.1 ± 0.2 Ma; 40 Ar/ 39 Ar incremental heating dating on whole-rock paralava) and continues until now. An active combustion process on scree from a coal seam and clastic Eureka Sound Group sedimentary rocks was observed on Ellesmere Island.

Rocks exposed along both sides of the Smith Sound in Ellesmere Island and NW Greenland record the tectono‐sedimentary evolution of the whole Phanerozoic, including two periods of mountain building—the Palaeozoic Ellesmerian Orogeny and the Palaeogene Eurekan Orogeny—and the formation of two major sedimentary basins, the Franklinian and the Sverdrup Basins. We used geo‐ and thermochronology and apatite chemistry data to unravel this evolution. Apatite fission track and (U‐Th)/He dates vary strongly from >600 to <100 Ma. We present internally consistent thermal history models, which allow to explain the data variations by a unitized exhumation and burial history. Our models suggest that the cratonic areas were buried beneath a several km‐thick succession of Franklinian Basin deposits. During the Ellesmerian Orogeny, the craton acted as sediment source, as also suggested by the composition of apatite and by U‐Pb ages of zircon contained in Devonian foreland sediments. The Ellesmerian foreland was buried by up to 4–5 km thick strata on top of the preserved sedimentary rocks. During the Triassic, the Sverdrup Basin strongly widened and extended at least ∼370 km further toward the east, as compared with previous reconstructions of the basin based on the preservation of Triassic deposits. Thermal history modeling suggests Late Cretaceous to early Cenozoic reheating, which may be caused by deposition associated with the Eurekan Orogeny and/or enhanced heat flow associated with continental breakup. Our data also show that low‐temperature thermochronology is not suitable for resolving potential strike‐slip movements along the Wegener Fault.

Eastern North Greenland is a key area for studying the reorganisation of the North Atlantic-Arctic Realm during the Cenozoic. Due to its crucial position at the intersection of Atlantic Ocean, Arctic Ocean, and the West Greenland Rift Basin this area was significantly involved in the Eureka Orogeny leading to intracontinental compression/transpression observed on the Svalbard-Barents margin and the Canadian Archipelago as well as Northern Greenland. In the Neogene the final breakup occurred in this area, leading to the deep-water connection of the Arctic and North Atlantic Oceans. It is characterized by the Carboniferous-Paleogene deposits of the Wandel Sea Basin overlaying Mesoproterozoic to early Palaeozoic supracrustal rocks. They occur in a series of pull apart basins along a zone of NE-SW-oriented faults. These faults are part of the DeGeer Shear Zone, along which the lateral offset of Greenland and Spitsbergen occurred during the Eureka Orogeny. In accordance the deposits are deformed, but the timing and the structural context of the deformation is much debated. Also, some deposits show unusually high thermal maturities of which the origin and geodynamic context is unclear. We took samples across the Tolle-Land-Fault-Zone from the coast in the NE into the Caledonian basement in SW and applied apatite fission tack analysis and (U-Th-Sm)/He thermochronology to reconstruct the thermal history of the respective segments of the fault zone and their thermal evolution in respect to the deformation and opening of the northern Atlantic. Preliminary results will be presented and the exhumation history and timing of deformation and thermal anomalies in eastern North Greenland and influence of the breakup will be discussed.

During expedition PS115/1, the German research vessel Polarstern acquired seismic refraction data along a 102 -km-long profile crossing Greenland's northern continental margin and extending up to the southwestern limit of the Morris Jesup Spur. A P-wave velocity model is obtained and validated by gravity modelling. A nearby seismic reflection line provides insights on the structures within the sedimentary cover. Beneath a 2-km-thick sedi-mentary cover with velocities of 1.8 km/s to 3.4 km/s, an up to 1.5-km-thick layer is characterized by velocities of 4.2 km/s and is interpreted to consist of volcanic rocks. This is consistent with proposed volcanic activity on the Morris Jesup Spur and exposed volcano-sedimentary rocks of the nearby Kap Washington Group. Below the volcanic rocks, an up to 7 km-thick unit with velocities of 4.4 to 5.8 km/s is interpreted to consist of meta -sedimentary rocks still belonging to the deformed units of the Franklinian Basin. The seismic reflection data image a tectonic overprint of the acoustic basement and the lowermost sedimentary layers. Tectonic faults indicating the tectonic overprint do not reach to the uppermost sedimentary layers. This hints at an older fracture zone that is also observed in the velocity model and aligns well with observed anomalies in the regional gravity and magnetic fields. The seismic velocity model reveals a highly extended continental crust that shows a magmatic overprint at all crustal levels. The upper crust is 5 km thick with a velocity of 6.0 km/s. However, in three distinct zones its thickness is up to 8 km and the velocity increases to 6.3 km/s. These zones are interpreted as magmatic intrusions into the upper crust. The lower crust represents a 9-km-thick high-velocity layer (7.2 km/ s) that is interpreted as magmatic underplating or lower crustal sill intrusions. Such a high-velocity lower crust is not present in models of adjacent Arctic margins. PACS: 0000, 1111 2000 MSC: 0000, 1111

Svalbard's Northwestern Basement Province is traditionally divided into the Albert I Land and the Biscayarhalvøya terranes. New U–Pb age data on zircon and monazite and structural and geochemical data provide first evidence of early Paleozoic deposits south of the Biscayarhalvøya Terrane indicating the possible existence of a third terrane: the Germaniahalvøya Terrane. This area is represented by a Cambro-Ordovician succession of mica schist and marble (Lernerøyane Group) and its higher-grade metamorphic equivalent (Liefdefjorden Migmatite Complex), which were affected by the Taconian phase (migmatization at c. 469 Ma) and the Scandian phase ( c. 422–415 Ma) of the Caledonian Orogeny. During the Scandian phase, the ductile Lerner Deformation Zone was formed. New isotopic data from the eclogite-bearing Richarddalen Complex of the Biscayarhalvøya Terrane imply the formation as an Ordovician–Silurian collision-related mélange dominantly composed of c. 730 to 600 Ma Timanian island-arc-derived detritus and igneous rocks, partly eclogite-facies metamorphosed at c. 656 Ma, and Tonian meta-igneous rocks. After amphibolite-facies metamorphism of the mélange matrix at c. 423 Ma, the Richarddalen Complex and the Stenian–Tonian Biscayarfonna Group were juxtaposed and mylonitized by the dextral Biscayarhalvøya Deformation Zone. Supplementary material: The complete geochemical and U-Pb isotope geochemical dataset as well as additional figures are available at https://doi.org/10.6084/m9.figshare.c.5778735

During the Devonian, the Svalbard Archipelago lay at low latitudes, occupying a paleogeographic position at the intersection of Caledonian and Ellesmerian orogens. Provenance analysis, including detrital zircon U-Pb age studies, of Devonian (ca. 420-360 Ma) strata from the Andree Land Basin, Svalbard, help reconstruct sediment sources to understand the assembly of the three basement provinces that make up Svalbard, which are presently separated by Devonian sedimentary basins and(or) faults with syn-to post-Devonian displacement. The studied Andree Land Group strata, which are part of the North Atlantic's Old Red Sandstone, consist of the Early Devonian Wood Bay Formation and Middle to Late Devonian Mimerdalen subgroup. Paleocurrent indicators from Lower to lower-Middle Devonian strata record north-directed sediment transport. Detrital zircon U-Pb ages indicate a prominent "Caledonian" signal and include sources from Svalbard's Northwestern and(or) Southwestern basement provinces. In Middle and Upper Devonian strata, paleocurrents and detrital zircon ages record a shift to a predominantly eastern-northeastern provenance, likely from the uplifting Ny-Friesland block along the Billefjorden Fault Zone. Late Ediacaran-early Cambrian detrital zircons in the uppermost Planteryggen Formation (Frasnian) indicate extrabasinal sources possibly associated with the Timanian orogen of Northern Baltica. The combined provenance data suggest Svalbard may have already been assembled, similar to the modern block, with the Andree Land Basin located between modern exposures of the Southwestern/Northwestern and the Northeastern basement provinces. Comparison of detrital zircon ages from Andree Land Group strata with those from other circum Arctic Devonian strata provides constraints on Svalbard's paleogeographic position in the Devonian.

During the Devonian, the Svalbard Archipelago lay near the equator, occupying an important paleogeographic position at the intersection of Caledonian and Ellesmerian orogens. We provide new sediment provenance constraints, including detrital zircon U-Pb ages, from the Devonian Andrée Land Basin, Svalbard, to understand the tectonic history of the archipelago at that time. Sedimentary provenance analysis of Devonian aged strata can help reconstruct the sediment sources and paleogeography to understand the assembly of the domains that make up Svalbard, that are presently separated by Devonian sedimentary basins and(or) faults with syn- to post Devonian displacement. The studied Andrée Land Group strata in Dicksonland, which are part of the North Atlantic's Old Red Sandstone, consist of the Early Devonian Wood Bay Formation and Middle to Late Devonian Mimerdalen subgroup. Paleocurrent indicators from Lower to lower-Middle Devonian strata record north-directed sediment transport. Detrital zircon U-Pb data are dominated by ages sourced from Svalbard’s Northwestern and Southwestern Basement provinces. In Middle and Upper Devonian strata, paleocurrents and detrital zircon ages suggest a shift to a predominantly eastern-northeastern provenance, likely sourced from the uplifting Ny-Friesland block along the Billefjorden Fault Zone. The addition of significant late Ediacaran-early Cambrian detrital zircons in a sample from the uppermost Planteryggen Formation (Frasnian) indicate sources associated with the Timanian orogen and provide a useful palaeogeographic indicator when compared to other regional detrital zircon data sets. Detrital zircon ages and provenance data suggest Svalbard may have already been assembled, similar to the block we see today, with the Andrée Land Basin between modern exposures of the Southwestern/Northwestern and the Northeastern basement provinces. Comparison of detrital zircon ages from Andrée Land Group strata with those from other circum Arctic Lower, Middle, and Upper Devonian strata provides further insight on Svalbard’s paleogeographic position in the Devonian.

The Eurekan deformation is a partially contractional Cenozoic tectonic event that affected large parts of the Arctic region. In the study area on northern Ellesmere Island, major NE-SW trending strike-slip faults occur, which are related to the Eurekan deformation. The outcrop data show that left-lateral strike-slip kinematics slightly dominate, but also right-lateral kinematics were documented. Cross-cutting relationships of the indi-vidual faults give evidence for multiple fault reactivations within major strike-slip zones. The reconstructed paleostress fields show two phases. The first phase started with a N-S compression and shifted over a NNE-SSW compression into a NNW-SSE compression. The second phase was a WNW-ESE compression. The paleostress field evolution reflects the movements of Greenland. During the Eurekan phase 1, Greenland moved northward and during Eurekan phase 2 it moved to the WNW. These motions likely controlled the stress field on northern Ellesmere Island. From the paleostress field analyses and the orientation of the strike-slip faults in the study area, it can be derived that the Eurekan phase 1 deformation is characterized by left-lateral strike-slip faults, whereas most-likely during Eurekan phase 2 the majority of right-lateral strike-slip faults formed. The paleostress field analysis implies that many Eurekan faults are reactivated Ellesmerian faults. Recent seismic events indicate ongoing tectonic activity at some of the major strike-slip faults. This sheds new light on the geodynamics of northern Ellesmere Island, which was mechanically coupled to the Greenland plate, and implies that under the recent stress field, earthquakes at strike-slip faults are still possible and some of these faults were active in at least three phases over the last 350 Myr.

Paleoproterozoic gneisses of the Ellesmere–Devon crystalline terrane on southeastern Ellesmere Island are deformed by metre-scale, east-striking mylonite zones. The shear zones commonly offset pegmatitic dikes and represent the last episode of ductile deformation. Samples were dated by the 40Ar/39Ar step-heating method to put an upper limit on the time of deformation. Biotite from one tonalitic protolith and five shear zones give geologically meaningful results. Clusters of unoriented biotite grains pseudomorph granulite-facies orthopyroxene in some of the weakly deformed gneisses, whereas the shape-preferred orientation of biotite defines the mylonitic fabric. The intrusive age of the tonalitic protolith is 1958 ± 12 Ma, based on previous U–Pb dating of zircon. 40Ar/39Ar analysis of biotite from the same sample gave a plateau age of 1929 ± 23 Ma, which is interpreted as cooling from regional granulite facies metamorphism. Three nearby samples of mylonitic tonalite have 40Ar/39Ar ages in the range of ≈1870–1840 Ma. Biotite from two granitic mylonites over 80 km away return high-resolution Ar spectra in the same range, implying that widespread ductile shearing occurred at ≈1870–1840 Ma, or ≈90 million years after cooling from regional metamorphism. Although the 2.0–1.9 Ga gneisses of southeastern Ellesmere Island correlate with the Inglefield Mobile Belt in North-West Greenland and the Thelon Tectonic Zone, the late shear zones are superimposed on that juvenile arc long after the 1.97 Ga Thelon orogeny.

Prior to break up of Greenland and Svalbard, the Wandel sea basin with Carboniferous to Cenozoic deposits formed in eastern North Greenland. These deposits were affected by the last major period of Arctic tectonism, the Eocene Eurekan deformation. Vitrinite reflectance data from late Cretaceous rocks long the east coast of North Greenland indicate unusual high thermal maturity in association with a swarm of quartz veins, which exceeds the thermal maturity associated with the Eurekan deformation further inland. This pattern is also observed in Cenozoic sediments further to the north as well as along the conjugated North Atlantic margin, in western Svalbard. However, cause and origin of the elevated heat flow indicated by thermal maturity values are not known so far and the timing is not well constrained. We test the hypothesis whether this pattern was established coevally along both margins of the North Atlantic and marks a post-Eurekan thermal event. Vitrinite reflectance data indicate temperatures high enough to reset low temperature chronometers, therefore we used apatite fission track (AFT) and (U-Th-Sm)/He (AHe) thermochronology to determine the age of the high thermal maturation and associated quartz veins formation. Our data reveals a more complex thermal history than hypothesized: For the eastern North Greenland margin thermal history modelling of the combined AFT and AHe ages indicates a pre-Eurekan phase of elevated heat flow between 72 Ma and 66 Ma causing the high vitrinite reflectance and the formation of the quartz veins in the late Cretaceous rocks. Additional petrographic and electron microprobe analysis reveals the growth of feldspar, hematite, amphibole, and tourmaline within the quartz veins. According to most paleogeographic reconstructions, northern Greenland was located to the south of Svalbard close to a volcanic province near Bear Island. Heating may thus be associated with incipient igneous activity of that area, related to initial North Atlantic opening. A second phase of elevated heat flow between 58 Ma and 52 Ma is indicated by thermal history modelling of the AFT and AHe ages from the Cenozoic rocks further north. This frames the timing of the initiation of the dextral displacement between Greenland and Svalbard and might be associated with heat transfer along the transform fault from the active spreading centres in the North Atlantic and the Arctic Ocean. Contrasting to the results of North Greenland, thermal history modelling of AFT and AHe ages from the Cenozoic rocks of western Svalbard reveals heating throughout the Eocene and onset of cooling only during the early Oligocene for the Svalbard margin. Thus, even though we cannot exclude a similar thermal history during the Paleocene to early Eocene, the eastern North Greenland and western Svalbard margins are characterized by a differential thermal evolution during the ~middle Eocene to Oligocene. In conclusion, our data show that the thermal history of the conjugated continental margins along the northern North Atlantic is characterized by episodic heat flow variations predominantly controlled by oceanic plate tectonic processes.

Paleogene rocks from Svalbard yield exceptionally high vitrinite reflectance values up to 4%. Even higher vitrinite reflectance data, along with high bitumen reflectance values, are found from Cretaceous to Paleogene rocks of the conjugated northeast Greenland margin. These rocks also contain coke. Since the distinct pattern of high thermal maturity affects both sides of the Fram Strait, it is interpreted to be caused by a heating event during a time when Greenland and Svalbard / Eurasia were still contiguous or close together. As heating overprints Paleogene sediments, we further assume that it postdates the Eocene Eurekan deformation and is related to subsequent (trans-)tensional movement leading to continental separation and eventually to the opening of the Fram Strait. The Fram Strait is the only deepwater connection of the Arctic Ocean with other oceans and is key for understanding the climatic, tectonic and paleo-oceanographic evolution of the Arctic realm. Timing and trigger mechanisms for mid- to late Miocene tectonic activity around the Fram Strait are still poorly constrained. For this study, we will test the following hypotheses using apatite fission track and apatite (U-Th-Sm)/He thermochronology: (i) Heating of the west and east side of the Fram Strait occurred simultaneously and was caused by incipient sea floor spreading in the Fram Strait; (ii) heating occurred during mid- to late Miocene in relation to uplift/exhumation and enhanced magmatic activity. Vitrinite reflectance data indicate temperatures high enough to reset low-temperature thermochronometers, thus our results will allow to date the thermal event and to investigate how it was temporarily and spatially connected to the separation of Greenland from Svalbard and thus to the opening of the northern North Atlantic Ocean and the Fram Strait. First Data will be presented.