The Paleoproterozoic magmatic-metamorphic events and cover sediments of the Tiekelik Belt and their tectonic implications for the southern margin of the Tarim Craton, northwestern China

The Tiekelik Belt in the southwestern part of the Tarim Craton, NW China, consists of Archean-Paleoproterozoic orthogneisses, and granitoids, and younger sedimentary successions. U-Pb dating of Paleoproterozoic rocks in the Tiekelik Belt has provided new information on the southwestern margin of the Tarim Craton. Two orthogneisses from the Heluositan Complex yielded crystallization ages in the interval 2310-2260 Ma and metamorphic ages of 2040-2007 Ma and 1830 Ma, respectively. Two syenogranites from the Buweituwei pluton yielded crystallization ages of 1900 and 1795 Ma. Detrital zircon analyses from sedimentary rocks nonconformably overlying the Buweituwei and Akazi plutons indicate maximum depositional ages between 1950 Ma and 1780 Ma. Major detrital inputs are from the basement in the region and form prominent peaks at 1900-1800 Ma and 2300-2200 Ma. Our new data, combined with previous results, allow us to summarize the Archean-Paleoproterozoic tectonic evolution of the Tiekelik Belt as follows: (1) Emplacement of Archean-aged TTG magmas during the 3.14-2.76 Ga interval; (2) A series of 2.41-2.26 Ga magmatic events that represent an important period of crustal reworking within the Tarim craton; (3) 2.03-1.80 Ga magmatic and metamorphic events that include the emplacement of a 1.9 Ga mafic dyke suite into the Heluositan Complex along with several episodes of intraplate magmatism. The late magmatic events are coeval with metamorphism and may support an orogenic extensional model for the Tiekelik Belt during the 1.9-1.8 Ga interval; (4) post-1.8 Ga subsidence and formation of a Changcheng sequence in the Tiekelik Belt. The Paleoproterozoic ages of major tectonothermal events within the Tiekelik, North Altyn-Dunhuang block and Alashan block are almost identical and it is argued that they were connected at that time as North China and Tarim were part of the larger Columbia supercontinent. (C) 2014 Elsevier B.V. All rights reserved.