华南地质2025，Vol.41Issue(3)：482-494,13.DOI:10.3969/j.issn.2097-0013.2025.03.002
粤东北长塘盆地晚白垩世钾玄质火山岩成因及构造环境
Origin and Tectonic Setting of Late Cretaceous Shoshonitic Volcanic Rocks in Changtang Basin,Northeastern Guangdong Province
摘要
Abstract
The Mesozoic acidic volcanic rocks developed in the Changtang Basin,northeastern Guangdong,constitute an important component of the coastal volcanic belt in southeastern China.This study presents whole-rock major and trace element analyses together with zircon U-Pb geochronology to investigate the petrogenesis of these volcanic rocks and their implications for regional tectonic evolution.Zircon U-Pb dating yields weighted average 206Pb/238U ages of 99.8±1.5 Ma,99.2±0.77 Ma,and 99.8±1.3 Ma,indicating that these rocks were formed during the Late Cretaceous.The acidic volcanic rocks are characterized by high alkali content(Na2O+K2O=8.38-8.87 wt.%),high K2O(4.85-8.07 wt.%),high Al2O3(11.45-12.90 wt.%),and low TiO2(0.11-0.33 wt.%).They are enriched in large-ion lithophile elements such as Rb,K,and Pb,and depleted in high-field-strength elements such as Nb,Ta,and Ti,exhibiting typical shoshonitic afinities.It is suggested that the acidic volcanic rocks in the Changtang Basin were likely derived from partial melting of lower crustal metasedimentary rocks and subsequently experienced significant fractional crystallization in shallow magma chambers.Their formation is interpreted as the product of crustal partial melting induced by the asthenospheric upwelling following the rollback of the subducting Paleo-Pacific Plate,indicating an extensionaltectonicsettinginthisregionduringtheLateCretaceousassociatedwiththeretreatofthePaleo-PacificPlate.关键词
晚白垩世/钾玄质岩石/伸展环境/长塘盆地/东南沿海/华南Key words
Late Cretaceous/shoshonitic rocks/extensional environment/Changtang basin/the southeastern coastal/South China分类
地质学引用本文复制引用
江云川,邵小阳,黄继春,邓飞,卓伟华..粤东北长塘盆地晚白垩世钾玄质火山岩成因及构造环境[J].华南地质,2025,41(3):482-494,13.基金项目
广东省自然资源厅项目(2022-11) （2022-11）
