摘要
腾冲地块高地热异常区清水左所营初糜棱岩化黑云母二长花岗岩岩体、新华黑石河热田强糜棱岩化黑云母二长花岗岩岩体、热海热田硫磺塘硅化碎裂正长花岗岩岩体变形变质、岩石地球化学及锆石年代学的研究表明,晚白垩世（73Ma）初糜棱岩化黑云母二长花岗岩岩体为高温钾玄质强过铝花岗岩,形成于活动大陆边缘火山弧-后碰撞转换或过渡构造环境,并经历强烈伸展变形作用,普遍发育早期近水平-低角度（〈30°）韧性伸展剪切糜棱面理,局部发育晚期高角度右旋走滑挤压韧性糜棱面理;始新世（48-46Ma）强糜棱岩化黑云母二长花岗岩岩体、硅化碎裂正长花岗岩岩体为中-高温钾玄质强过铝花岗岩,并具铝质A型花岗岩特征,形成于后碰撞-板内构造环境,以发育晚期高角度（70°-87°）右旋走滑挤压韧性糜棱面理为特征,其右旋走滑韧性剪切变形时代晚于始新世（48-46Ma）。晚白垩世-始新世钾玄质强过铝花岗岩的形成与俯冲-碰撞造山隆升后的伸展垮塌、拆沉地幔物质上涌玄武质岩浆底侵和地壳部分熔融作用密切相关。始新世-第四纪岩浆活动与高地热异常区（带）空间上密切伴生,新近纪晚期-第四纪构造活动主要表现为脆性走滑-拉张正断层和构造拉分断陷盆地的形成,构造断陷边界断裂与深部岩浆活动是导致腾冲地区高地热异常区（带）中-高温地热温泉沿走滑-拉张断裂带集中分布的主要原因。
Within the high geothermal anomaly areas in the Tengchong block,proto-mylonitic biotite monzonitic granite, ultramylonitized biotite monzonitic granite and silicified fractured syenogranite,are exposed in Zuosuoying of Qingshui,Heishihe of Xinhua,and Liuhuangtang of Rehai,respectively. Studies of deformation,metamorphism,petro-geochemistry and geochronology suggest that Late Cretaceous（ 73Ma） proto-mylonitic biotite monzonitic granite is a high temperature shoshonitic and strongly peraluminous granite formed in an active continental margin volcanic arc to a post-collisional tectonic setting. This granite has an early nearly horizontal（ 30°） stretching shear mylonitic foliation,with locally developed later high-angle dextral strike-slip extrusion mylonitic foliation. Eocene（ 48 ~ 46Ma） ultra-mylonitized biotite monzonitic granite and silicified fractured syenogranite are mediumhigh temperature shoshonitic and strongly peraluminous A-type granites,which formed in a post-collisional environment to a within plate tectonic setting,where late high-angle（ 70° ~ 87°） dextral strike-slip shear mylonitic foliations were developed. Late CretaceousEocene shoshonitic and strongly peraluminous granitic magmatism was associated with basaltic magma underplating and partial melting of the crust,generated by upwelling mantle,which resulted from extensional collapse and delamination following the subductioncollision orogenic uplift. Eocene-Quaternary magma activity was spatially associated with high geothermal anomaly areas. The tectonic evolution during Late Neocene to Quaternary is represented by the formation of the strike-slip faults and extensional normal faults associated with extensional fault basin. Accordingly,the boundary faults of fault basins as well as deep magmatism are the predominant reasons for the concentrated distribution of the medium-high temperature geothermal springs along the strike-slip extensional fault zones.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2014年第2期527-546,共20页
Acta Petrologica Sinica
基金
国土资源部深部探测技术与实验研究专项课题(201011060)资助
关键词
钾玄质强过铝花岗岩
变形变质
岩石地球化学
LA-ICP-MS
U-Pb定年
构造意义
高地热异常区
腾冲地块
Shoshonitic strongly peraluminous granites
Deformation and metamorphism
Petro-geochemistry
LA-ICP-MS U-Pb dating
Tectonic implications
High geothermal anomaly areas
Tengchong block
