摘要
东南极普里兹湾地区出露大量泛非期花岗质岩类,利用LA-ICP-MS锆石U-Pb原位定年方法测得达尔克花岗岩、蒙罗克尔花岗岩和阿曼达花岗岩的年龄分别为519±2Ma,497±2Ma和498±7Ma。所有普里兹湾地区花岗岩类均具有较高的全碱含量以及K_2O/Na_2O、FeO^T/(FeO^T+MgO)和10~4Ga/Al比值,较低的Mg、Ca、Cr和Ni丰度,表现出A型花岗岩的特点,同时还富集大离子亲石元素和稀土元素,不同程度亏损Sr、Nb、Ta、P和Ti,并具有高^(87)Sr/^(86)Sr初始比值和低ε_(Nd)(t)值的同位素特征。研究结果表明,普里兹湾地区的岩浆活动可能与后碰撞的造山作用有关,包括岩石圈减薄、岩浆底侵和地壳伸展作用等。普里兹湾A型后碰撞花岗岩的确定支持普里兹带为碰撞造山带的构造属性。
Voluminous granitic plutons from the Prydz Bay of East Antarctica were emplaced during the Pan-African period. Using LA-ICP-MS U-Pb zircon technique, the Dalkoy, Munro Kerr and Amanda granites were dated at 519 ± 2Ma, 497 ± 2Ma and 498 ± 7Ma, respectively. All granitoids are geochemically characterized by having high total alkali contents, low Mg, Ca, Cr, Ni contents and high K20/Na20, FeO^T/（ FeO^T ＋ MgO） and 10^4Ga/Al ratios, in accord with A-type granites. These rocks also show LILE- and HREE-enriched patterns with variable trough at Sr, Nb-Ta, Ti and P, and have very low initial εNd （t） values and high initial ^87 Sr/^86 Sr ratios. This suggests that magmatism in Prydz Bay is probably related to the post-collisional orogeny, including lithospheric thinning, magmatic underplating and crustal extension. The occurrence of post-collisional A-type granitoids from Prydz Bay supports the suggestion that the Prydz Belt may represent a collisional orogen.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2007年第5期1055-1066,共12页
Acta Petrologica Sinica
基金
国家自然科学基金(40372046)
国土资源大调查项目(1212010511505)资助
关键词
东南极
普里兹湾
花岗岩类
后碰撞
East Antarctica, Prydz Bay, granitoids, post-collision
