大别山东段棋盘石A型花岗岩成因及其地质意义  

Genesis and Geological Significance of Qipanshi A-type Granite in the Eastern Dabie Mountain

作　　者：张振 ZHANG Zhen(No.313 Geological Team,Anhui Province Bureau of Geology and Mineral Exploration,Liuan,Anhui 237010)

机构地区：[1]安徽省地质矿产勘查局313地质队,安徽六安237010

出　　处：《四川地质学报》2025年第1期3-11,共9页Acta Geologica Sichuan

基　　金：安徽省公益性地质(科技)工作项目“秦岭~大别造山带东段(安徽部分)钼金多金属成矿规律与找矿方向研究(2009-g-19)”。

摘　　要：大别山造山带东段梅山杂岩体主要由棋盘石中细粒正长花岗岩、三合中细粒二长花岗岩、九王寨中细粒花岗闪长岩和槐树湾细粒石英闪长岩组成,其中棋盘石正长花岗岩具有典型A型花岗岩的地球化学特征,其他单元则具有I型花岗岩属性。据此,可以认为梅山地区岩体产出的花岗岩类属于浅成I-A型花岗岩组合。锆石U-Pb测年结果表明,棋盘石正长花岗岩形成于约115 Ma,与沙坪沟致矿花岗斑岩形成年龄(114 Ma)基本一致。南部零星出露的石鼓洼斑状二长花岗岩具有明显较粗粒的岩石结构,其形成时间早于其他侵入岩单元,而形成深度则明显大于其他侵入岩单元。由此可见,梅山地区岩体的形成经历了两个明显不同的构造阶段:石鼓洼单元形成后发生了强烈的地壳抬升剥蚀,然后是浅成I-A型花岗岩组合的侵位,棋盘石正长花岗岩属于碰撞后A型花岗岩。The Meishan complex in the eastern part of the Dabie Mountain orogenic belt is mainly composed of Qipanshi fine-grained syenite granite,Sanhe medium-fine-grained monzonitic granite,Jiuwangzhai medium-fine-grained granodiorite and Huaishuwan fine-grained quartz diorite.The Qipanshi syenite granite has the geochemical characteristics of typical A-type granites,and other units have the properties of I-type granites.Therefore,it can be considered that the granites in the Meishan area belong to the hypabyssal I-A type granitic assemblage.Zircon U-Pb dating results show that the formation age of Qipanshi syenite granite is about 115 Ma,which is basically the same as that of Shapinggou ore-bearing granite porphyry(114 Ma).The Shiguwa porphyritic monzonite granite sporadically exposed in the south has obviously coarse-grained rock texture,and its formation time is earlier than other intrusive rock units,and the formation depth is obviously larger than other intrusive rock units.It can be seen that the formation of the rock mass in Meishan area experienced two distinct tectonic stages:strong crustal uplift and denudation occurred after the formation of the Shiguwa unit,and then the emplacement of the hypabyssal I-A-type granite assemblage.TheQipanshi syenite granite belongs to the post-collision A-type granite.

关 键 词：大别山造山带 A型花岗岩 正长花岗岩 

分 类 号：P588.1[天文地球—岩石学] P611.1[天文地球—地质学]