| 华北克拉通南缘小秦岭地区花岗质浅色脉体锆石U-Pb年龄、稀土元素特征及其地质意义 |
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| 关键词:southern North China Craton Paleoproterozoic granitic leucosomes anatexis zircon U-Pb dating rare earth element |
| 基金项目:国家自然科学基金项目(编号: 41772217; 41872225);中国地质调查局地质调查项目(编号: 12120114014101) |
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| Zircon U-Pb Ages and Trace Element Compositions of Granitic Leucosomes from the Xiaoqinling Area in the Southern Margin of the North China Craton and Its Geological Implications |
| Numerous granitic leucosomes formed during the Late Paleoproterozoic are developed in the Xiaoqinling area of the southern North China Craton (NCC), providing an important window for understanding the crustal melting and tectonic evolution of the southern NCC during this period. In this study, cathodoluminescence (CL) images, U-Pb chronology and rare earth elements (REE) of zircons from three granitic leucosomes in the Xiaoqinling area are studied. The CL images exhibit patched, planar or weakly oscillatory zonings with euhedral external morphologies, which are typical for anatectic zircons. Zircon U-Pb dating yields 207Pb/206Pb ages of (1867±13) Ma (MSWD=0.22, n=21), (1849±17) Ma (MSWD=0.79) and (1828±15) Ma (MSWD=0.33, n=20), representing the timing of partial melting in this area. Corresponding to the three groups ages, the zircon chondrite normalized REE diagrams show the transition from the relative enrichment of heavy rare earth elements (HREEs) with weak Eu anomalies (Eu/Eu*=0.12–0.81) to nearly flat HREE patterns with medium negative Eu anomalies (Eu/Eu*=0.29–0.61), and then to an enrichment of HREEs with obvious negative Eu anomalies (Eu/Eu*=0.15–0.54), titanium-in-zircon temperature suggests that the crystallization temperatures are between 574 °C and 708 °C, implying that crustal anatexis occurred during the post-peak upper amphibolite-facies to granulite-facies stages. Combined with previous metamorphic chronological data, it is inferred that the anatexis occurred during 1.87~1.82 Ga in the Xiaoqinling area can be linked to the protracted uplift and cooling process of the previously thickened crust caused by the collision and amalgamation of the Eastern and Western Blocks at ~1.95 Ga. |
| WANG Hong-hui,CHEN Hong,CHEN Long-yao,BAI He,ZHANG Huan-huan.2022.Zircon U-Pb Ages and Trace Element Compositions of Granitic Leucosomes from the Xiaoqinling Area in the Southern Margin of the North China Craton and Its Geological Implications[J].Acta Geoscientica Sinica,43(5):633-644. |
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