粤东地区中生代火成岩的时空分布,岩石特征及成岩物化条件

THE TIME-SPACE RELATION AND CHARACTERISTICS AND FORMING PHYSICOCHEMICAL CONDITIONS OF MESOZOIC IGNEOUS ROCKS IN EASTERN GUANGDONG AREA

粤东地区中生代火成岩广泛发育。系统的岩石学和同位素地质年代学研究表明,其时空分布具有明显的规律性,结合其岩石化学和地球化学研究,认为本区中生代火成岩广义上为火山—侵入杂岩系,并可划分为早晚两期。岩石具I型和S型或同熔型和改造型的过渡性特征。成岩温度750—1100℃,压力3.0—11·0×10~8Pa,形成深度10—36km,成岩物质来源于地壳,且以上地壳源为主。

The eastern Guangdong area has widespread distribution of volcanic and intrusive rocks produced by violent tectonic- magmatic activities during the 'Mesozoic era. Sysmatic petrological studieds and isotopic age determinations show that the time-space distribution of the Mesozioic igneous rocks in this area has distinct regularities. And acceding to the studies on petrochemistry and geochemistry, it is concluded that they are volcanic-intrusive complex series. They can be divided into earlier and later Yenshania period granitoids. They belong to transition type between I-and S-type or between anatexes-and transform-type. The temperatures, pressures and depths of the formed volcanic-intrusive rocks are 750-1100℃ , 3. 0-11. 0× 108Pa and 10-36km, respectively. Their souce rocks were in the crust, mainly the upper crust.