CAJ | 학술논문

对滇西梁河地区早白垩世闪长岩岩株中的花岗闪长岩和闪长岩进行了LA-ICP-MS锆石U-Pb年龄测试，获得206Pb/238U年龄分别为118.7Ma±1.5Ma和119.8Ma±1.0Ma，表明它们与早白垩世花岗岩体基本同时形成。其中在闪长岩中发现1颗约140Ma的岩浆锆石，可能指示梁河地区早白垩世初期的岩浆事件，2颗晚三叠世锆石继承核的年龄分别为208.2Ma±6.7Ma和221.9Ma±2.4Ma，记录了印支期的岩浆活动。花岗闪长岩和闪长岩具有相似的全岩εNd(t)值(-8.03、-7.70)，但却表现出不均一的锆石εHf(t)值(118.7Ma：-5.60~-3.28；119.8Ma：-6.73~-3.09)，表明它们来自于结晶基底重熔的长英质岩浆与幔源岩浆的混合。不同锆石的Hf同位素组成显示，与北冈底斯带相比，滇西梁河地区早白垩世幔源组分参与花岗质岩石形成的程度较低。滇西梁河地区花岗闪长岩和闪长岩的形成，可能与地壳加厚的构造背景有关。
대전서량하지구조백성세섬장암암주중적화강섬장암화섬장암진행료LA-ICP-MS고석U-Pb년령측시，획득206Pb/238U년령분별위118.7Ma±1.5Ma화119.8Ma±1.0Ma，표명타문여조백성세화강암체기본동시형성。기중재섬장암중발현1과약140Ma적암장고석，가능지시량하지구조백성세초기적암장사건，2과만삼첩세고석계승핵적년령분별위208.2Ma±6.7Ma화221.9Ma±2.4Ma，기록료인지기적암장활동。화강섬장암화섬장암구유상사적전암εNd(t)치(-8.03、-7.70)，단각표현출불균일적고석εHf(t)치(118.7Ma：-5.60~-3.28；119.8Ma：-6.73~-3.09)，표명타문래자우결정기저중용적장영질암장여만원암장적혼합。불동고석적Hf동위소조성현시，여북강저사대상비，전서량하지구조백성세만원조분삼여화강질암석형성적정도교저。전서량하지구화강섬장암화섬장암적형성，가능여지각가후적구조배경유관。
This paper has reported zircons LA-ICP-MS U-Pb data of granodiorite and diorite from early Cretaceous diorite stock in Lianghe, with 206Pb/238U ages being 118.7Ma ± 1.5Ma and 119.8Ma ± 1.0Ma respectively, indicating that they were emplaced at about the same time with Early Cretaceous granite. A magmatic zircon sample of the diorite gave a 206Pb/238U age of ca. 140Ma, im-plying an earlier Early Cretaceous magmatic event;two inherited zircon samples recorded Indo-China magmatism with 206Pb/238U ag-es being 208.2Ma ± 6.7Ma and 221.9Ma ± 2.4Ma. The granodiorite and diorite show similar whole rock εNd(t) values of-8.03 and-7.70, but they have different heterogeneous Hf isotopic compositions of zircons, with variable εHf(t) values being-5.60~-3.28 and-6.73~-3.09 respectively, indicating that they were generated by mixing of crystalline basement-derived felsic melts with man-tle-derived basaltic magma. Different Hf isotopic compositions between Lianghe granite and Northern Gangdise Belt granites suggest that the contribution of the mantle-derived magma to granitic rock was less in Lianghe than in Northern Gangdise Belt in early Cre-taceous. The granodiorite and diorite were probably produced from a crustal thickening setting.