Miao, Tengfeng, Zhao, Xu, Huizenga, Jan Marten, Li, Xiaolong, Lai, Lianxin, Li, Bin, Zhu, Hongtao, Zhang, Xinxin, Zhou, Hongzhi, and Wei, Junhao (2026) Segmented Paleo-Tethys subduction and its role in driving Triassic magmatism within the Elashan Tectonic-Magmatic Belt, northern Tibetan Plateau. Lithos, 522-523. 108387.

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Abstract

Segmented subduction redirects mantle flow and melt, controlling orogenic magmatism and deformation. The Elashan Tectonic-Magmatic Belt (ETMB) lies between the East Kunlun (EKOB) and West Qinling (WQOB) orogenic belts, linked to Triassic Paleo-Tethys subduction. We present geological, geochemical, zircon U–Pb geochronological, and Hf-Sr-Nd isotopic data from Triassic ETMB granites, supplemented by data from the EKOB and WQOB. The ca. 244 Ma Shiduolong granodiorites display high MgO and enriched εHf (t) (-6.8 to -3.6) values, indicating mixing between crust-derived felsic and mantle-derived mafic melts. The ca. 229 Ma Huda diorites, with low Sr/Y and depleted εHf (t) (-3.0 to -0.7) values, originated from a shallow juvenile lower crust at high-temperature conditions. The Saishitang complex comprises ca. 220 Ma quartz diorite porphyrites and granodiorites, plus ca. 215 Ma diorites. The quartz diorite porphyrites exhibit high-Mg andesite affinities and linear (87Sr/86Sr)i-SiO2 correlation, suggesting partial melting of enriched mantle peridotites with assimilation and fractional crystallization. The granodiorites display high-Mg adakitic characteristics formed by melting of delaminated lower crust. The diorites are geochemically similar to the Huda diorites but exhibit more enriched εHf (t) values (ranging from -9.2 to -4.8), suggesting an older and deeper crustal source. Notably, the 240–230 Ma ETMB granitoids record high εHf (t) values and a depletion trend, which is in contrast with the concurrent enrichment in the adjacent EKOB and WQOB. This implies that, although they were in a contiguous subduction setting, unique dynamics related to the asthenosphere upwelling occurred in the ETMB, related to a slab window between the EKOB and WQOB. The inferred slab window was likely produced by slab tearing, controlled by slab segmentation in response to an along-strike transition from slab rollback in the WQOB to a relatively low-angle subduction regime in the EKOB.

Item ID:	90205
Item Type:	Article (Research - C1)
ISSN:	1872-6143
Keywords:	Elashan Tectonic-Magmatic Belt, Granitoids, Segmented subduction zones, Slab window, Paleo-Tethys
Copyright Information:	© 2025 Published by Elsevier B.V.
Date Deposited:	06 Jan 2026 23:30
FoR Codes:	37 EARTH SCIENCES > 3705 Geology > 370511 Structural geology and tectonics @ 50% 37 EARTH SCIENCES > 3703 Geochemistry > 370303 Isotope geochemistry @ 50%
SEO Codes:	28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280107 Expanding knowledge in the earth sciences @ 100%
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