Abstract:

The Proterozoic Xingxingxia Complex is the oldest exposed unit in the Eastern Segment of the Central Tianshan Tectonic Zone (ESCTTZ), which consists mainly of amphibolites and various parametamorphic rocks, and was intruded by MesoNeoproterozoic and Palaeozoic granitoid gneisses. The SHRIMP UPb dating of detrital zircon from a schist sample of the Xingxingxia Complex in the ESCTTZ yielded three distinct ages of  ~1 800 Ma, 1 530 Ma and 1 200 Ma, suggesting that the sediments derived not only from Palaeoproterozoic and Early Mesoproterozoic precursors but also from Late Mesoproterozoic precursors. The minimum detrital zircon age of (1 189±65) Ma, which is consistent with the ca. 12 Ga islandarc magmatic activity, could provide a significant constraint on the maximum depositional age for these sediments. In addition, the zircons from the schist sample also give two ages of about 910 and 470 Ma, respectively. The former is interpreted as the age of metamorphism; the latter, which is identical, within error, to the emplacement age of the identified Palaeozoic granotoid gneiss sample, is attributed to the disturbance of the Palaeozoic tectonothermal event. The ages of magmatic (ca. 1 200 Ma) and metamorphic (ca. 910 Ma) events in the ESCTTZ are akin to the ages of geologic events reported elsewhere in South China, East Antarctica, South Australia and southwestern North America, which signifies that the ESCTTZ may have played a crucial role in the assembly of the supercontinent Rodinia.

Key words: SHRIMP data; tectonothermal events; tectonic evolution; Rodinia; ESCTTZ