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Abstract <p>The Sin Quyen formation in the Phan Si Pan zone, northwestern Vietnam, is predominantly composed of paragneiss, mica schist, and migmatite, and contains abundant ancient detrital zircon. The principal rock-forming minerals include quartz (17–32%), K-feldspar (27–35%), plagioclase (25–40%), biotite (2–5%), and muscovite (3–5%). Accessory minerals are mainly apatite, zircon, and minor ore minerals. Geochemical characteristics indicate high SiO<sub>2</sub> contents (72.58–84.59 wt %) and Al<sub>2</sub>O<sub>3</sub> (10.13–14.52 wt %), but low TiO<sub>2</sub> (0.22–0.24 wt %), total Fe<sub>2</sub>O<sub>3</sub> (0.9–3.66 wt %), MnO (0.00–0.03 wt %), MgO (0.21–1.51 wt %), CaO (0.04–1.02 wt %), and P<sub>2</sub>O<sub>5</sub> (0.02–0.07 wt %). The total rare earth element (REE) content ranges from ΣREE = 108.26 to 851.28 ppm, with light REEs being dominant (average ΣLREE = 356.99 ppm) and heavy REEs subordinate (average ΣHREE = 21.15 ppm. Major- and trace-element geochemistry indicate that the Sin Quyen formation was derived from felsic continental sediments deposited in a passive continental margin setting, subsequently subjected to high-grade metamorphism and migmatization. Strongly negative ε<sub>Hf</sub>(<i>t</i>) values (–9.4 to –9.7) and average two-stage Hf model ages (<i>T</i><sub>DM2</sub>) of 3.35–3.49 Ga demonstrate that the sedimentary protoliths of the Sin Quyen formation originated from ancient continental crust rather than juvenile mantle-derived magmas. Comparison of zircon ε<sub>Hf</sub>(<i>t</i>)-age data with those from Vietnam, the Yangtze block, the North China block, and the India block suggests that the Sin Quyen formation in the Phan Si Pan zone has a close affinity with the Yangtze Block, supporting the interpretation that the Phan Si Pan zone represents an extension of this block.</p>

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Petrogenesis of Sin Quyen Paragneiss, Phan Si Pan Zone, Northwest Vietnam and Geological Significance

  • 期刊论文

  • 发表日期：

    2026年2月22日

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  • Pham Minh,
  • Nguyen Thanh Tung

摘要

Abstract

The Sin Quyen formation in the Phan Si Pan zone, northwestern Vietnam, is predominantly composed of paragneiss, mica schist, and migmatite, and contains abundant ancient detrital zircon. The principal rock-forming minerals include quartz (17–32%), K-feldspar (27–35%), plagioclase (25–40%), biotite (2–5%), and muscovite (3–5%). Accessory minerals are mainly apatite, zircon, and minor ore minerals. Geochemical characteristics indicate high SiO2 contents (72.58–84.59 wt %) and Al2O3 (10.13–14.52 wt %), but low TiO2 (0.22–0.24 wt %), total Fe2O3 (0.9–3.66 wt %), MnO (0.00–0.03 wt %), MgO (0.21–1.51 wt %), CaO (0.04–1.02 wt %), and P2O5 (0.02–0.07 wt %). The total rare earth element (REE) content ranges from ΣREE = 108.26 to 851.28 ppm, with light REEs being dominant (average ΣLREE = 356.99 ppm) and heavy REEs subordinate (average ΣHREE = 21.15 ppm. Major- and trace-element geochemistry indicate that the Sin Quyen formation was derived from felsic continental sediments deposited in a passive continental margin setting, subsequently subjected to high-grade metamorphism and migmatization. Strongly negative εHf(t) values (–9.4 to –9.7) and average two-stage Hf model ages (TDM2) of 3.35–3.49 Ga demonstrate that the sedimentary protoliths of the Sin Quyen formation originated from ancient continental crust rather than juvenile mantle-derived magmas. Comparison of zircon εHf(t)-age data with those from Vietnam, the Yangtze block, the North China block, and the India block suggests that the Sin Quyen formation in the Phan Si Pan zone has a close affinity with the Yangtze Block, supporting the interpretation that the Phan Si Pan zone represents an extension of this block.