2. 防灾科技学院地球科学学院，河北三河065201

锆石Lu － Hf 同位素及岩石地球化学研究。结果表明，花岗闪长岩中26 个锆石测点的206 Pb /238U 加权平均年龄为( 118. 96 ± 0. 77) Ma ( MSWD = 0. 29) ; 岩体中锆石的εHf( t) 值均为正值( + 1. 4 ～ +3. 2) ，且具有较年轻的Hf 二阶段模式年龄( tDM2 = 1. 09 ～ 0. 98 Ga) ; 花岗闪长岩表现为富Al、高K 和Na 以及低Ti、P、Ca 的钙碱性I 型花岗岩地球化学特征，显示出轻稀土富集、重稀土元素亏损的稀土

元素组成特征; 样品锆石的εHf( t) 的值为偏低的正值，表明岩浆物质来源应为壳幔混源。结合岩石

地球化学投图以及区域构造背景演化认为，花岗闪长岩和花岗斑岩均属于后碰撞－ 火山弧花岗岩，研

究区的成矿成岩作用与太平洋板块强烈俯冲背景下的下岩石圈地幔拆沉有直接关系。

2. College of Earth Sciences，Institute of Disaster Prevention，Sanhe 065201，Hebei，China

( t) values of zircons in the rock mass are all positive ( + 1. 4 ～ + 3. 2) ，with young Hf two-stage model age ( TDM2 = 1. 09 ～ 0. 98 Ga) ． Geochemically，the granodiorite is rich in Al，K，

Na，and depleted in Ti，P，Ca，indicating calcium alkaline I-type granite． For rare earth elements ( ＲEE) composition，the granodiorite is enriched in light ＲEE and depleted in heavy ＲEE． Combined with the low positive εHf

( t) values，it is indicated that the magma is from a mixing source between crust and mantle． Based on the petrogeochemical mapping and the evolution of the regional tectonic background，both the granodiorite and granite porphyry belong to post-collision volcanic arc granites． The metallogenic diagenesis of the study area is directly related to the lower lithosphere mantle delamination under the tectonic environment of intense subduction of the Paleo － Pacific

Ocean plate．