摘要
云开造山带条带—眼球状(环斑)深熔花岗岩(含紫苏花岗岩)地球化学和年代学的研究表明,绝大多数花岗岩的A／ CNK>1．1,CaO／Na2O=0．62-1．61(平均0．94,大于0．3),Al2O3／TiO=16．6-60．6(平均23．68),高场强元素Ta、Nb、Zr 亏损,具大陆边缘俯冲-碰撞造山带后碰撞构造环境强过铝(SP)高钾钙碱性-钙碱性花岗岩的特征,紫苏花岗岩和片麻状含榴黑云二长花岗岩Al2O3／TiO(平均17．82)明显低于条带-眼球状(环斑)黑云二长花岗岩Al2O3／TiO(平均29．55),显示其形成温度更高,并具A型花岗岩的演化特征．而且从高钾钙碱性条带-眼球状(环斑)黑云二长花岗岩到钙碱性紫苏花岗岩、片麻状含榴黑云二长花岗岩,形成时代由(465±10)Ma、(467±10)Ma变为(435±11)Ma、(413±8)Ma,表明扬子板块与华夏板块在加里东期发生了洋—陆俯冲—碰撞造山和后碰撞的伸展—拆沉—底侵岩浆岩作用,并且后期又经历了海西—印支期挤压抬升和伸展揭顶作用的改造,这也为华南存在加里东期扬子板块向华夏板块的洋-陆俯冲-碰撞造山提供了重要证据．
There are different theories about the genesis and age of banded-augen （rapakivi） anatectic granitoids （charnockire）, which outcrop extensively in Yunkai region, western Guangdong Province. Their petrochemistry, chronology, deformational and metamorphic structures were studied. The petrochemical features of most granitoids are： A/CNK〉I. 1, Cao/ Na2O=0.62-1. 61 （average 0.94,〉0.3）, Al2O3/TiO= 16.6-60.6 （average 23.68）, loss high field strong elements Ta, Nb,Zr, strong peraluminous high-K calc-alkaline and calc-alkaline granitoids in a post-collisional tectonic enviroment of subduction-collision orogenic belt in an active-continental margin. The temperatures of charnockite and gneissic garnet-bearing biotite monzonitic granite are obviously higher than that of bandecl-augen （rapakivi） biotite monzonitic granite, and charnockite and gneissic garnet-bearing biotite monzonitic granite with the evolutional characterics of A-type granites. From bandedgranite, augen （rapakivi） biotite monzonitic granite to charnockite and gneissic garnet-bearing biotite monzonitic granite, the forming ages are （465±10） Ma, （467 ± 10） Ma, （435±11 ） Ma and （413±8） Ma respectively, and become younger. These results show that there were oceanic-continental subduction collision and post-collisional extension-delamination-underplating between the Yangtze and Cathaysia plates during the Caledonian, and they experienced compressional uplift and extensional exhumation during the Indosinian. It provides important evidence of the oceanic-continental subduction-collision of the Yangtze plate downward to the Cathaysia plate during the Caledonian in South China.
出处
《地球科学（中国地质大学学报）》
EI
CAS
CSCD
北大核心
2006年第1期110-120,共11页
Earth Science-Journal of China University of Geosciences
基金
国家自然科学基金项目(No.40072069)中国地质调查局项目(No.200313000041)
关键词
云开造山带
加里东期
强过铝深熔花岗岩
后碰撞构造环境
伸展-拆沉-底侵作用.
Yunkai orogenic belt
Caledonian
strong peraluminous anatectic granitoids
post-collisional tectonic enviroment
extension-delamination-underplating.
