安永梅

摘要：对比分析了安徽省沿江地区早白垩世侵入岩体的岩石地球化学特征，探讨了该区中酸性侵入岩体的岩浆源区演化特征。该区燕山期侵入岩主要形成于晚侏罗世和早白垩世，早白垩世岩浆源区具壳幔混合源特征，主要来自富集地幔，与部分地殼物质发生混染而成，其时空分布于岩浆成矿带内的矿集区具有高度吻合性。

关键词：中酸性—侵入岩；源区；演化；沿江

基金项目：安徽省科技项目“安徽省矿产资源与地质环境图集[项目编号：2012-k-8]”资助。

Spatial and Temporal Distribution of Intermediate-acid Intrusive Rocks and Evolution Characteristics of Magma Source Area along the Yangtze River in Anhui Province

AN-Yong mei1

Geological Surveying and Mapping Technology of Anhui Province，Hefei 230022

Abstract： The spatio-temporal distribution of intermediate-acid intrusive rocks along the Yangtze River in Anhui Province is compared and analyzed， and the evolution characteristics of magma source area of intermediate-acid intrusive rocks in this area are discussed. The magma of the intermediate-acid intrusive rocks in this area was formed in Yanshanian Period and in Late Jurassic and Early Cretaceous. The source areas of magma formation are characterized by crust-mantle mixing， mainly from enriched mantle and mixed with upper and lower crust. However， the evolution trend of crustal source materials of intermediate-acid intrusive source rocks from Late Jurassic to Early Cretaceous is increasing.

Key words：Intermediate-acid intrusive rocks； source regio； evolution

安徽沿江地区晚侏罗世至早白垩世侵入岩出露广泛，其中早白垩世期侵入岩可划分为两期：早期（134Ma～ 128Ma）代表性岩体为凤凰山、沙溪、清水塘、鸡冠石等岩体，分布于安庆—贵池、铜陵、庐枞、宁芜、繁昌矿集区等地。晚期（127～114M）代表性岩体为金口岭、花山、滨江、枞阳、洪镇等岩体，主要产于庐枞矿集区。

1.岩石地球化学特征

沿江地区早白垩世侵入岩主量元素SiO2含量在53.61%～76.71%之间，平均值为63.31%；TiO2含量在0.15%～19.13%之间，平均值为2.58%；Al2O3含量在0.3%～18.86%之间，平均值为14.15%；CaO含量在0.03%～9.24%之间，平均值为 3.61%；MgO含量在0.01%～2.16%之间，平均值为0.78%；MnO含量在0.02%～0.66%之间，平均值为0.06%；P2O5含量在0.01%～0.52%之间，平均值为0.23%；Na2O含量在0.2%～ 8.6%之间，平均值为4.25%，K2O含量在1.65%～10.1%之间，平均值为4.15%；ALK（Na2O+K2O）含量在3.86%～12.29%之间，平均值为8.40%，K2O/Na2O含量在0.22～2.48之间，平均值为1.06。碱铝比（NK/A=（K2O+Na2O）/Al2O3，mol）在0.48～1.40之间，铝过饱和度A/CNK值（Al2O3/（CaO+K2O+ Na2O），mol）在0.47～1.76之间，主体属于准铝质岩石类型，部分为过铝质岩石类型。在TAS图解中（图1），该区侵入岩样品主要落在二长岩、石英二长岩、花岗闪长岩、花岗岩区域，碱性和亚碱性系列岩石。

稀土元素ΣREE范围在95.38～1039.99×10-6，平均值242.73×10-6；……