Cooling and denudation history of Spitsbergen, and inferences for tectonics, climate and longterm landscape evolution
Zusammenfassung der Projektergebnisse
Spitsbergen, the main island of the Svalbard archipelago, is characterized by a remarkable geological architecture and geomorphologic pattern. Its northern part merely exposes Proterozoic and Paleozoic basement, while the south is covered by Mesozoic deposits and a Central Tertiary Basin including coal measures of considerable maturity. Moreover, the West Spitsbergen Fold Belt on the western margin shows a distinctive alpine morphology that contrasts with the plateau and tableland landscape of the main part of Svalbard. Aim of the research was to study the exhumation history of Spitsbergen on the base on thermochronological data and complementary paleo-thermal information. These constraints provide profound insight into tectonic processes, climate evolution and uplift, and to conclude on the opening of the Atlantic and regional long-term landscape and climate evolution. The project produced a comprehensive data set of ~75 apatite fission-track (AFT) ages between 36 and 214 Ma and associated proxies, ~100 single (U-Th-Sm)/He ages (AHe; sample ages 10 – 93 Ma), 15 vitrinite reflectance (VR) data, and clay mineralogical, geochemical and petrographic analyses. Thermal history modelling and qualitative interpretation of these data infers different exhumation scenarios for northern and southern Spitsbergen. Northern Spitsbergen experienced erosion in the order of 2 – 3 km, locally up to ~6 km, since the Early Jurassic. A common stage of Jurassic – Cretaceous exhumation was probably related to extensional tectonics during the opening of the Amerasian Basin. Mesozoic fault-related block exhumation was followed by discontinuous Paleocene – mid-Miocene erosion and uplift, perhaps including some phases of stagnation and re-deposition. In contrast, central and southern Spitsbergen hosted a Mesozoic sedimentary basin until ~45 Ma, and subsequently underwent a complex exhumation history comprising early Eocene – mid Miocene erosion of <2.7 km, and erosion since ~10 Ma removing <1.6 km of strata. Elevated Paleocene – early Eocene heat flow (~80 – 120 mW/m2) triggered the maturation of strata within the Central Tertiary Basin, but decreased to 40 – 70 mW/m2 concomitant with basin inversion. Heat flow variation correlates with plate-tectonic changes and likely indicates a transformation from an extensional to a foreland basin setting. Uplift since ~10 Ma generating the modern topography may be linked to thermal erosion of the mantle lithosphere beneath Svalbard.
Projektbezogene Publikationen (Auswahl)
- örr, N., Lisker, F., Clift, P., Carter, A., Gee, D., Tebenkov, A. & Spiegel, C. (2012): Late Mesozoic−Cenozoic exhumation history of northern Svalbard and its involvement into arctic basin formation processes: constraints from apatite fission track data. – Tectonophysics, 514-517, 81-92
Dörr, N., Lisker, F., Clift, P., Carter, A., Gee, D., Tebenkov, A. & Spiegel, C.
- (2013): Petrography and geochemistry of siliciclastic rocks from the Central Tertiary Basin of Svalbard – implications for provenance, tectonic setting and climate. – Zeitschrift der Deutschen Geologischen Gesellschaft, 164, 173-186
Schlegel, A., Lisker, F., Dörr, N., Jochmann, M., Schubert, K. & Spiegel, S.
(Siehe online unter https://doi.org/10.1127/1860-1804/2013/0012) - (2013): Why is Svalbard an island? – Tectonics
Dörr, N., Clift, P., Lisker, F. & Spiegel, C.
(Siehe online unter https://doi.org/10.1002/tect.20039)
