摘要
本文通过对大别山腹地的花岗岩、混合岩和变质岩的实地观察,并利用钾-氩,氩-氩和铷-锶等不同方法所进行的同位素年代学研究,证明大别山区于133—117Ma之间,曾发生过一次强烈的构造岩浆热事件。在这一构造岩浆热事件中,伴随着深度可达下地壳或更深层的多层次由北东向南西的逆冲型韧性剪切变形,表明当时大别山区仍处于强烈的深层陆-陆叠覆造山作用之下。经这一构造热事件产生的具角闪岩相的变质岩、混合岩及代表深层次的构造变形,现已出露地表,证明由大别群所组成的地块,绝不是长期边受剥蚀的隆起陆块或地盾,大别山现今的面貌,是近100Ma以来才形成的。
A strong tectono-magrnatic thermal event has been revealed by field observations of granitic, migmatitic and metamorphic rocks in the hinterland of the Dabie Mountains. K-Ar, Ar-Ar and Rb-Sr determinations show that the event took place 133—117 Ma ago (Yanshanian) Contemporaneously, a southwestward ductile shearing at multiple levels occurred in the lower crust or at even deeper levels, suggesting that the Dabie Mountains region was still under the influence of strong continent-continent, oblique overlapping tectonism of the Yangtze block under the Sino-Korean block at depth. The metamorphic rocks of the amphibolite facies, migmatites and deep structural deformations caused by this tectonothermal event are now exposed to the surface. The present features of the Dabie Mountains thus have appeared only since 100 Ma. The block composed of the Dabie Group is absolutely not an uplift or shield which had undergone a long-continued erosion.
出处
《地质学报》
EI
CAS
CSCD
北大核心
1991年第4期329-336,共8页
Acta Geologica Sinica
基金
"中朝准地台南缘构造岩浆演化及其与南华北含油气盆地的关系"(1989)专题研究报告成果之一。
