摘要
北秦岭太白岩体位于商丹构造带北侧。野外侵入关系和LA-ICP-MS锆石U-Pb定年显示,该岩体由早志留世的五里峡岩体、晚三叠世的红崖河岩体和早白垩世的下板寺岩体组成。五里峡岩体的主要岩石类型为片麻状黑云母二长花岗岩,锆石U-Pb年龄为(431±2)Ma;红崖河岩体的主要岩石类型为黑云母二长花岗岩,锆石UPb年龄为(214±2)Ma;下板寺岩体为粗粒黑云母花岗岩,锆石U-Pb年龄为(130±1)Ma,表明太白岩体是由3个不同时代岩体组成的侵入复合杂岩体。结合区域构造背景和前人的研究成果,得出早志留世五里峡岩体可能与秦岭微板块沿商丹缝合带俯冲碰撞有关;晚三叠世红崖河岩体与秦岭早中生代主期岩浆作用一致,是华北地块与扬子地块碰撞的产物;燕山期的下板寺花岗岩属于板内岩浆作用。研究显示,今后应注意大岩体的解体,其可能隐含着不可忽视的构造-岩浆作用信息。
The Taibai pluton is located on the northern side of Shangdan suture in the North Qinling Mountains. Field relationship and LA-ICP-MS zircon U-Pb dating suggest that this rock body consists of the early Silurian Wulixi- a pluton, the late Triassic Honyahe pluton and the early Cretaceous Xiabansi pluton. The main rock type of the Wulixia pluton is gneissie biotite monzogranite with an age of （431 ± 2） Ma, the Honyahe pluton is biotite mon- zogranite with an age of （214± 2） Ma and the Xiabansi Dluton is coarse-grained biotite granite with an age of（130±1） Ma. These ages suggest that Taibai pluton has experienced at least three tectonlc-magmanc events. According to regional tectonic setting and previous researches, the Wulixia pluton was related to the subduction and collision of the micro plate of Qinling Mountains along Shandan suture, the Honyahe pluton was formed by the collision of the North China Block with the Yangtze Block, and the Xiabansi pluton belonged to intraplate magmatism. It is thus thought that big batholith might contain more information of tectono-magmatic activities.
出处
《矿床地质》
CAS
CSCD
北大核心
2014年第1期37-52,共16页
Mineral Deposits
基金
地质调查项目(编号:1212010012012
1212010811033和12120113090200)的资助
