The Caledonian tectonothermal evolution of the Northwestern Terrane, Svalbard
(English)Article in journal (Refereed) Submitted
Mineral-chemical data of metapelites from the Proterozoic Krossfjorden Complex constrain the Late Caledonian tectonic evolution of Svalbard’s Northwestern Terrane and record a clockwise P-T path. The oldest deformation event (D2) related to orogenesis in the Northwestern Terrane records crustal thickening and incipient melting of the crust at c. 430 Ma. Continued heating during prograde metamorphism at c. 420 Ma resulted in the main migmatization event (D3) and related granitoid genesis at c. 850 °C and >6 kbars. Following the peak P-T conditions, the crust was uplifted and cooled to 645-683 °C and 3-5k bars. Unconformably above the Late Silurian aged high-T rocks and granitoid intrusives are Early Devonian (c. 416-411) cover sequences indicating rapid exhumation of the crystalline basement. This suggests that the peak metamorphic conditions were followed by near isothermal decompression. The clockwise P-T-t path of the Krossfjorden Complex of Svalbard’s Northwestern Terrane is remarkably similar to rocks from the Krummedal Sequence and Smallefjord Sequence of central East Greenland, confirming the close link between these areas prior to the Late Caledonian orogeny.
Svalbard, East Greenland, Caledonides, migmatites, clockwise P-T
Earth and Related Environmental Sciences
IdentifiersURN: urn:nbn:se:su:diva-39363OAI: oai:DiVA.org:su-39363DiVA: diva2:319609