The foreland-propagating thrust architecture of the East Greenland Caledonides 72°-75°N

A.K. Higgins, S. Elvevold, J.C. Escher, K.S. Frederiksen, J.A. Gilotti, N. Henriksen, H.F. Jepsen, K.A. Jones, F. Kalsbeek, P.D. Kinny, A.G. Leslie, M.P. Smith, K. Thrane, G.R. Watt

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Abstrakt

Systematic geological mapping of the East Greenland Caledonides demonstrates that the orogen is built up of WNW-directed thrust sheets displaced across foreland windows. The foreland windows in the southern half of the orogen are characterized by a thin (220-400 m) Neoproterozoic to Lower Palaeozoic succession, structurally overlain by two major Caledonian thrust sheets (Niggli Spids and Hagar Bjerg Thrust Sheets). The metasediments of the upper-level Hagar Bjerg Thrust Sheet host 940-910 Ma granites and migmatites formed during an early Neoproterozoic thermal or orogenic event, as well as Caledonian 435-425 Ma granites and migmatites. The uppermost unit of the thrust pile, the Franz Joseph Allochthon, comprises a very thick (18.5 km) Neoproterozoic to lower Palaeozoic sedimentary succession (Eleonore Bay Supergroup, Tillite Group, Kong Oscar Fjord Group). Total westward displacement of the thrust sheets was about 200-400 km, with shortening estimated at 40-60%. Major extensional faults post-date thrusting. Restoration of the thrust sheets indicates that the sequence of Caledonian orogenic events now preserved in East Greenland was initiated several hundred kilometres ESE of present-day East Greenland, as Baltica and its marginal assemblage of Early Palaeozoic accretions began to impinge on the Laurentian margin.

OriginalsprogEngelsk
Sider (fra-til)1009-1026
Antal sider18
TidsskriftJournal of the Geological Society
Vol/bind161
Udgave nummer6
DOI
StatusUdgivet - dec. 2004

Programområde

  • Programområde 4: Mineralske råstoffer

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