Age and tectonic setting of volcanic rocks of the Tamulangou Formation in the Great Xing’an Range, NE China

• The volcanic rocks of the Tamulangou Formation are diachronous, spanning the Middle to Late Jurassic time.
• The volcanics were formed in post-orogenic extension after closure of the Mongol–Okhotsk Ocean.
• The volcanic rocks of the Tamulangou Formation exhibit a significant subduction polarity from northwest to southeast, both in terms of age and geochemistry.

Zircon U–Pb chronological and geochemical research has been undertaken on the volcanic rocks of the Tamulangou Formation in the Zhalantun area, middle part of the Great Xing’an Range in NE China. The volcanic rocks yield ages of ∼147 Ma (the Late Jurassic), 14–17 Myr younger than volcanic rocks of the same formation in the northern part of the Great Xing’an Range, indicating that volcanism spanned the Middle–Late Jurassic. The Tamulangou volcanic rocks, together with the JixiangFeng Formation and rhyolite of the Shangkuli Formation, constitute bimodal volcanics related to widespread coeval A-type granites, suggesting the Tamulangou Formation volcanics formed in an extensional environment. Spatial variations in petrological, geochronological, and geochemical features of the volcanic rocks of the Tamulangou Formation indicate subduction to the southeast following orogenesis and closure of the Mongol–Okhotsk Ocean.