CAJ | 학술논문

为探讨中越边境 Song Chay 穹窿中片麻状花岗岩的形成及演化，对穹窿北端的老城坡片麻状花岗岩进行了年代学和地球化学研究。结果表明，老城坡片麻状花岗岩的 LA-ICP-MS 锆石 U-Pb 年龄为415.4±5.2Ma，属于过铝质高钾钙碱性 S 型花岗岩，SiO2含量为73.48％～77.16％，全碱含量较高（K2 O ＋Na2 O ＝7.40％～7.86％），K2 O ／N 2 O ＝0.99～1.75（均值为1.30＞1），铝饱和指数（A ／CNK）为1.01～1.14。大离子亲石元素 K 和 Rb 相对富集，Ba、Sr 亏损明显；高场强元素 Th、U、Hf 相对富集，Ti、Nb 亏损，其中 Ti 强烈亏损。结合区域地质背景初步推断，岩浆源岩可能来自早期地壳物质部分熔融的产物；广西运动时期云开地体与桂滇—北越地体发生碰撞，导致老城坡岩体侵位于华南褶皱带。
위탐토중월변경 Song Chay 궁륭중편마상화강암적형성급연화，대궁륭북단적로성파편마상화강암진행료년대학화지구화학연구。결과표명，로성파편마상화강암적 LA-ICP-MS 고석 U-Pb 년령위415.4±5.2Ma，속우과려질고갑개감성 S 형화강암，SiO2함량위73.48％～77.16％，전감함량교고（K2 O ＋Na2 O ＝7.40％～7.86％），K2 O ／N 2 O ＝0.99～1.75（균치위1.30＞1），려포화지수（A ／CNK）위1.01～1.14。대리자친석원소 K 화 Rb 상대부집，Ba、Sr 우손명현；고장강원소 Th、U、Hf 상대부집，Ti、Nb 우손，기중 Ti 강렬우손。결합구역지질배경초보추단，암장원암가능래자조기지각물질부분용융적산물；엄서운동시기운개지체여계전—북월지체발생팽당，도치로성파암체침위우화남습추대。
To further explore the formation and evolution of gneissic granite in the Song Chay dome of the Sino-Vietnamese border,the paper studied the chronology and geochemistry of the Laochengpo gneissic granite in the north of the dome. The results showed that the Laochengpo gneissic granite is a peraluminous,high K and calc-alkaline S-type granitoid,with a LA-ICP-MS zircon U-Pb dating age of 41 5.4±5.2Ma.The granite contains 73.48%—77.1 6% of SiO 2 ,high total al-kalis (K2 O+Na2 O =7.40%—7.86%)and K2 O /N 2 O =0.99-1 .75 (with a mean of 1 .30),and high A /CNK of 1 .01 —1 .1 4.The LILE elements K and Rb are relatively enriched,Ba and Sr are relatively depleted,the HFSE elements Th,U, and Hf are relatively enriched,and Ti and Nb are relatively depleted with Ti is depleted the most in the Laochengpo gneissic granite.On the basis of the regional geological background,this study suggested that the magma source may be a product of partially melted early crustal materials;the Yunkai terrane collided with the Yunnan-North Vietnam terrane dur-ing the Guangxi movement,which resulted in the emplacement of the Laochengpo plutons into the South China fold belt.