Geochronology and geochemistry of Upper Paleozoic sandstones at Tiekelike, NW China: Implications for the tectonic evolution of the southwestern margin of the Tarim Block

Exposed volcanic–sedimentary rocks in the Tiekelike Tectonic Belt (NW China) permit reconstruction of the Paleozoic paleogeographic environment and tectonic evolution of the southwestern edge of the Tarim Craton. This study presents new whole-rock geochemical and detrital zircon U–Pb data for sedimentary rocks (i.e., sandstones) of the Upper Devonian Qizilafu Formation (QF), Upper Carboniferous Kalawuyi Formation (KF), and Lower Permian Tahaqi Formation (TF) from the Tiekelike Uplift. The sandstones of the QF, KF, and TF are mainly derived from from acid to intermediate igneous source rocks and subsequently underwent medium to intense chemical weathering and variable degrees of sedimentary recycling. Trace element ratios suggest that these rocks were formed in an active continental margin. Zircon grains from the three study units yield dissimilar age distributions, weighted toward relatively older ages for QF (peaks at ca. 443 Ma, 788 Ma, 1138 Ma, and 2548 Ma) and younger ages for KF (peaks at ca. 449 Ma and 951 Ma) and TF (peaks at ca. 280 Ma, 412 Ma, and 727 Ma). Based on the petrographic and geochemical features of the sandstones, along with detrital zircon U–Pb data, we propose that the QF, KF, and TF sandstones were most likely derived mainly from Early Paleozoic (ca. 496–349 Ma) igneous rocks of the West Kunlun Orogenic Belt, with a possible subordinate contribution from Paleozoic igneous rocks within the Tarim Block. These igneous rocks were widely developed during magmatic and tectonothermal events in the source area of the Tiekelike Uplift related to large-scale magmatic activity (ca. 320–230 and 496–349 Ma), assembly and breakup of the Rodinia supercontinent (ca. 999–717 Ma), assembly of the Columbia supercontinent (ca. 2171–1061 Ma), and a widespread cratonization event (ca. 2683–2533 Ma). We infer that Archean basement (ca. 3349–2533 Ma) may exist in the Tiekelike Tectonic Belt.