The Northernmost Mountain Belt on Earth: Birth and Death of the Eurekan Orogen in North Greenland

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.