Zircon ages and Hf isotopic compositions of plutonic rocks from the Central Tianshan (Xinjiang, northwest China) and their significance for early to mid-Palaeozoic crustal evolution

A new study on the Xinjiang Tianshan reveals significant crustal evolution during the early to mid-Palaeozoic era, marked by episodic juvenile crustal growth and reworking. The research, using zircon ages and Hf isotopic compositions from plutonic rocks, identifies distinct magmatic episodes: Early Ordovician (ca. 475–473 Ma) with mixed juvenile and crustal sources, Late Ordovician–Silurian (ca. 458–425 Ma) with two sub-episodes—one predominantly crustal and another juvenile—and Early to Mid-Devonian (ca. 410–393 Ma) with near-zero or negative εHf(t) values, suggesting complex mantle–crust interactions. The Late Devonian (ca. 368–361 Ma) granites, chemically similar to adakite but with low negative εNd(t) values, may indicate crustal delamination due to over-thickening. This study provides critical insights into the tectonic and magmatic processes shaping the Central Tianshan's crust.

Shi, Y., Jian, P., Kröner, A., Jahn, B.-M., Liu, D., Zhang, W., & Ma, H. (2014). Zircon ages and Hf isotopic compositions of plutonic rocks from the Central Tianshan (Xinjiang, northwest China) and their significance for early to mid-Palaeozoic crustal evolution. International Geology Review, 56(11), 1413–1434. https://doi.org/10.1080/00206814.2014.942807