摘要
中国东部中生代斑岩及其矿床同位素年龄研究表明,它们在时空分布上是与岩浆活动及构造运动的时空特征相呼应的。例如华南及长江中下游一带其时空分布与岩浆活动同步,由西向东逐渐变新。在东秦岭,斑岩的空间分布受东西构造控制,而时间演化上受北东向构造控制。本文还根据不同衰变系统封闭温度,讨论了成矿温度的上限。
The study on the isotopic ages of porphyries and pophyritic deposites suggests that the distribution of their time and space is related closely to the effect of magmatism and tectonism in eastern China.In the middle and lower reaches of Changjiang River, there are two types of porphyry of which one is accompanied by the Mesozoic volcanism with isotopic ages of 140-90 Ma, while the other has no relationship to the volcanism and its isotopic ages are 193-140 Ma. Both of them are getting younger and younger towards east.In the Qin Mountain, the arrangement of porphyritic groups appears to be controlled by the west-east tectonic line, but the distribution of their isotopic ages shows that the older porphyries had been affected by the north-east tectonic system after the Indosinia epoch. It is getting younger and younger towards west. For example, the K40-Ar40 model age is 177 Ma in Lushi area and 152 Ma, 138 Ma in Yuanjiagou, Heishan, Mulonggou. The Rb-Sr age is 132 Ma in Jinduicheng.The isotopic ages of porphyries in Inner Mongolia and Yanliao area are also discussed in this article.The upper limits of the metallization ages are deduced on the basis of closed temperature of different decay systems.
出处
《地质科学》
CAS
CSCD
北大核心
1989年第2期190-200,共11页
Chinese Journal of Geology(Scientia Geologica Sinica)
关键词
中生代
斑岩
同位素年代
Mesozoic porphyrite, Isotopic age, K^(40)-Ar^(40) model age
