华东地质2026，Vol.47Issue(1)：141-166,26.DOI:10.16788/j.hddz.32-1865/P.2025.01.007
桂东北地区鹰扬关群的构造属性:来自下龙组条带状磁铁石英岩的年代学约束
Tectonic affinity of the Yingyangguan Group in northeastern Guangxi:geochronological constraints from banded iron formation(BIF)of the Xialong Formation
摘要
Abstract
The Yingyangguan group in northeastern Guangxi,serving as a crucial area for reconstructing the early tectonic evolution of the South China Block,has long been subject to academic debate regarding its chrono-logical classification and tectonic affinity.To address this,we conducted detrital zircon U-Pb dating and Hf iso-tope analysis on banded iron formation(BIFs)from the Xialong Formation of the Yingyangguan Group,which exhibit continuous and traceable stratigraphic sequences.Three BIFs samples(YY21063,YY21074,and YY2302)yielded similar detrital zircon U-Pb age spectra,with dominant age peaks at 0.72-0.90 Ga,and subordi-nate populations at 0.90-1.30 Ga,1.62-1.99 Ga,2.12-2.36 Ga,and 2.43-2.64 Ga.Two samples(YY21063 and YY2302)displayed comparable zircon Hf isotopic compositions,with εHf(t)values ranging from-21.92 to 11.68,and-12.80 to 10.73,respectively.Their two-stage Hf model ages(TDM2)varied between 0.92-3.85 Ga and 1.09-3.31 Ga,indicating that the detrital materials were predominantly derived from the reworking of Mes-Paleo-proterozoic and Archean crustal sources.The youngest detrital zircon ages from all three samples consistently constrained the maximum depositional age of the Xialong Formation at 720 Ma,thereby confirming the Neopro-terozoic age of the Yingyangguan Group.The dominant 0.72-0.90 Ga zircon age population suggests that the pri-mary provenance was likely associated with Neoproterozoic magmatic events along the southeastern margin of the Yangtze Block.The continuous and traceable banded iron formations in the Xialong Formation indicate that the Yingyangguan Group represents a coherent sedimentary sequence rather than a tectonic mélange.Combined with the provenance signatures,we propose that the Yingyangguan Group formed in a rift-related tectonic setting,fur-ther elucidating the Neoproterozoic tectonic evolution of the South China Block.关键词
构造属性/磁铁石英岩/碎屑锆石U-Pb年龄/鹰扬关群/桂东北地区Key words
tectonic affinity/magnetite quartzite/detrital zircon U-Pb age/Yingyangguan Group/northeast-ern Guangxi分类
天文与地球科学引用本文复制引用
胡华轩,秦亚,吴杰,冯佐海,苟小芳,黄永高,刘奕志,范天一,王葆华..桂东北地区鹰扬关群的构造属性:来自下龙组条带状磁铁石英岩的年代学约束[J].华东地质,2026,47(1):141-166,26.基金项目
国家自然科学基金"桂东南云开地区前寒武纪变质基底的构造归属及对江南造山带西南段边界的约束(编号:42162018)"、广西自然科学基金"桂东北鹰扬关地区条带状磁铁石英岩的成因机制及其构造意义(编号:2025GXNS-FAA069322)"和广西高校中青年教师科研基础能力提升项目"桂东北鹰扬关地区条带状铁建造的地球化学特征及成因机制研究(编号:2024KY0268)"项目联合资助. （编号:42162018）
