摘要
针对吉林南部古老岩石测年数据偏新和太古宙与元古宙之间分界时限的混乱,本文运用Sm-Nd等时线法和锆石U-Pb法将吉林南部变质岩系划分为4个年龄段:前阜平旋回(>2600Ma);阜平旋回第一幕(2600～2500Ma);阜平旋回第二幕(2500～2400Ma);阜平旋回第三幕(2400～2350Ma)。阜平旋回第三幕归入太古宙并作为太古宙—元古宙之间分界时限,吉林南部古陆构造环境由活动趋向于稳定,新、老板块沟、弧、盆系统交替,地壳隆起、剥蚀引起K-Ar年龄偏新。该过渡性构造环境和原2500～2350Ma间地质事件归入太古宙将有助于加深对该区地壳演化、板石沟绿岩带铁矿及夹皮沟剪切带金矿化形成的认识。
In consideration of the fact that previous age data of the old rocks in southern Jilin were somewhat too young, and there is some confusion concerning the boundary between the Archaean and the Proterozoic Eon, this paper, by using the Sm-Nd isochron and zircon U-Pb dating methods, divides the metamorphic rocks in this region into 4 intervals: the pre-Fuping cycle (before 2600 Ma), the first phase (2600-2500 Ma) , the second phase (2500-2400 Ma) and the third phase (2400-2350 Ma) of the Fuping cycle. The third phase is classified into the Archaean and acting as the boundary between the Archaean and the Proterozoic. When the tectonic setting of the southern Jilin old land turned from active to stable, there occurred alternation of the trench-arc-basin system in the new and old plates, as well as crustal uplift and erosion, which resulted in the younger K-Ar ages. Therefore, to include the transitional tectonic setting and the geologic events occurring in the interval 2400 - 2350 Ma into the Archaean will be helpful to our understanding of the crustal evolution of this region, and the formation of the Banshigou greenstone belt iron deposit and the Jiapigou shear zone gold deposit.
出处
《地质论评》
CAS
CSCD
北大核心
2000年第2期197-202,共6页
Geological Review
基金
原地质矿产部重点基础科技 (编号95-02-013)
国土资源部变质动力开放实验室联合项目
关键词
变质岩系
太古宙-元古宙
分界时限
构造演化
metamorphic rocks
Archaean and Proterozoic boundary
tectonic evolution
southern Jilin
