Sources for detrital zircons in East Greenland sandstones
During recent years, GEUS has compiled a major database comprising detrital zircon U/Pb zircon age data from sedimentary and stream sediment samples from Greenland with the aim of establishing a North Atlantic Provenance Database. Currently, more than 400 samples of Proterozoic to Paleocene ages have been analysed in profiles from all East Greenland sedimentary basins from Kangerlussuaq in the south to Peary Land in the north to illustrate lateral as well as stratigraphic variations in provenance characteristics. Furthermore, the signature of the hinterlands to the sedimentary basins has been established by analysing the detrital zircon U/Pb age distribution in c. 100 stream sediment samples along the entire coast of East Greenland. In order to facilitate source-to-sink analysis in the North Atlantic region, available detrital zircon U/Pb age from sandstone samples from on- and offshore Norway and adjoining areas have been included in the the database, which at present includes more than 55.000 single zircon grain ages from around 650 samples. The stream sediment samples show that the fingerprint characteristics of the Franklinian Basin north of 80N is dominated by a Palaeoproterozoic and an Archaean population of zircons with peaks at ca. 1800 and 2700 Ma together with a range of Mesoproterozoic zircons. Orthogneiss is the dominating lithology between 76N and 80N and the stream sediments here yield a bimodal distribution of Palaeoproterozoic zircon ages with peaks at 1950 Ma dominating to the north and 1650 Ma dominating to the south. In the area south of 76N the hinterland signature is characterised by five end members: • Archaean zircons derived from the gneisses in the inner Scoresbysund area characterised by age distributions around 2800 Ma and with a small, but consistent Early Archaean population. • Palaeoproterozoic zircons derived from orthogneisses with a mix of 1950 Ma and 1650 Ma ages. In Liverpool Land the 1650 Ma age is the only Palaeoproterozoic age represented. • A range of Meso- and Palaeoproterozoic zircon ages with a majority of the latter, derived from reworking of the Neoproterozoic Krummedal and Eleonore Bay Supergroup sediments. • Caledonian zircons with ages of ca. 420 Ma mainly derived from S-type granites. • South of 68N, zircons are mainly derived from Archaean gneisses with a broad age distribution around 2800 Ma. The extensive data set of this web-based database and its associated analytical tools can be used to constrain sediment sources in the region. The zircon age distributions in post-Caledonian sandstones are generally characterised by zircons that could be derived from these end members. There are, however, exceptions where the sandstone contain zircons with Mesozoic and Neoproterozoic with ages that are exotic to East Greenland geology. The provenance of these sandstones contain components compatible with a derivation from the Ural Mountains or the Taimyr area in Northern Russia or the Permian volcanic province in the North Sea.
AAPG Datapages/Search and Discovery Article #90325 © 2018 AAPG Europe Regional Conference, Global Analogues of the Atlantic Margin, Lisbon, Portugal, May 2-3, 2018