胶辽吉造山带碰撞后岩浆作用:来自辽东-吉南地区巨斑状和球粒状花岗岩的约束  

Post-collisional magmatism from the Jiao-Liao-Ji orogenic belt:Constraints from mega-porphyritic and sphaeroidal granites in the eastern Liaoning-southern Jilin region,NE China

作　　者：赵岩[1,2] 杨宏智 陈井胜[1,2] 廉涛 张朋[1,2] 梁帅 吴新伟[1,2] ZHAO Yan;YANG HongZhi;CHEN JingSheng;LIAN Tao;ZHANG Peng;LIANG Shuai;WU XinWei(Shenyang Center of Geological Survey,CGS,Shenyang 110034,China;Northeast S&T Innovation Center of China Geological Survey,Shenyang 110034,China;Liaoning Province Seventh Geological Brigade Co.Ltd.,Dandong 118003,China)

机构地区：[1]中国地质调查局沈阳地质调查中心,沈阳110034 [2]自然资源部东北地质科技创新中心,沈阳110034 [3]辽宁省第七地质大队有限责任公司,丹东118003

出　　处：《岩石学报》2024年第11期3506-3519,共14页Acta Petrologica Sinica

基　　金：中国地质调查项目(DD20230329、DD20242674、DD20240059)资助.

摘　　要：胶辽吉造山带辽东-吉南地区卧龙泉、双岔、八河川等巨斑状花岗岩体形成于造山峰期之后,记录了造山带演化的重要信息,对于探讨整个胶辽吉造山带构造演化具有重要意义。通过对巨斑状花岗岩研究,识别出局部侵入其中的球粒状花岗岩,并对采集自造山带东部和西部典型岩体的3件巨斑状花岗岩和1件球粒状花岗岩开展了岩相学、锆石U-Pb年代学、Lu-Hf同位素及主微量元素研究。结果显示巨斑状花岗岩具有硅含量相对较低、全碱较高、A/CNK值变化较大(0.86~1.19)等特征。虽然双岔巨斑状花岗岩中见有石榴子石,但全岩地球化学特征表现出准铝质、锆饱和温度较高等A型花岗岩特征;宝甸地区花岗岩中也有石榴子石,显示了S型花岗岩地球化学特征。卧龙泉和双岔巨斑状花岗岩体侵位时代为1880~1895Ma,球粒状花岗岩形成于1870±13Ma,宝甸地区巨斑状含石榴花岗岩侵位于1845±13Ma左右;来自这些锆石的原位εHf(t)值介于-3.6~+4.2之间,相应的二阶段模式年龄为2474~2730Ma。本研究认为,辽吉造山带碰撞后花岗质岩石成因较为复杂:球粒状花岗岩反映了岩浆过冷度较大、快速侵位至浅表过程;宝甸地区巨斑状花岗岩具有S型花岗岩特征;具有A型花岗岩特征的巨斑状花岗岩则反映了深部物质和加厚地壳均有贡献。结合前期报道的同时代碰撞后I型和A型花岗岩以及变质岩的研究等,本文认为辽东半岛巨斑状和球粒状花岗岩的产出与胶辽吉造山带碰撞后强烈的下地壳作用有关,反映了造山带去根垮塌、岩石圈伸展过程,代表了碰撞后花岗质岩浆作用。The post-collisional granites in the Jiao-Liao-Ji orogenic belt(JLJB)consist of porphyritic plutons such as Wolongquan,Shuangcha and Bahechuan in the eastern Liaoning-southern Jilin region.These granites have great significance in limiting the tectonic evolution of this orogenic belt.We recognize sphaeroidal granite which intrude into the garnet bearing mega-porphyritic granites,and collect four representative samples(three mega-porphyritic granites and one sphaeroidal granite)from the east and west of the JLJB to take petrography,major and trace elements analysis,zircon U-Pb chronology,and Lu Hf isotope analysis.The results show that these granites have relatively low silicon contents,high total alkalinity,and A/CNK values ranging from 0.86 to 1.19.Although garnet is found in the Shuangcha mega-porphyritic granite intrusion,the mega-porphyritic granite also exhibits A-type granite features with high zirconium saturation temperatures and metaluminous content.Samples from the Baodian area show differentiated S-type granite characteristics.The Wolongquan and Shuangcha mega-porphyritic granite intruded between 1880~1895Ma,while the spherical granite crystallized at 1870±13Ma.The garnet bearing mega-porphyritic granite intrusion in the Baodian area intruded at 1845±13Ma.The in situεHf(t)values of zircons separated in the granites range from-3.6 to+4.2,with corresponding two-stage model ages ranging from 2474Ma to 2730Ma.The post-collisional granitic magmatism has a complex geological setting in the JLJB.The spherical granite reflects a high degree of subcooling and rapid emplacement of magma into the shallow surfaces of crust.The garnet-bearing mega-porphyritic granite in Baodian area has a characteristic of differentiated S-type granite.The A-type mega-porphyritic granite reflects contributions from both mantle material and thickened crust.Taking previous reports of contemporaneous post-collisional I-type and A-type granites into consideration,mega-porphyritic and spheroidal granites in the JLJB distributed under

关 键 词：巨斑状花岗岩 球粒状花岗岩 锆石年代学 LU-HF同位素 胶辽吉造山带 碰撞后岩浆作用 

分 类 号：P588.121[天文地球—岩石学] P597.3[天文地球—地质学]