滇东南麻栗坡一带片麻状花岗岩地球化学、年代学特征及其地质意义

发布时间：2018-02-01 13:26

本文关键词： SongChay穹窿片麻状花岗岩岩石地球化学 LA-ICP-MS锆石U-Pb定年 Hf同位素组成　出处：《中国地质大学(北京)》2015年硕士论文　论文类型：学位论文

【摘要】：为深入探讨中越边境Song Chay穹窿片麻状花岗岩的形成、演化及找矿前景,本文对穹窿北端的麻栗坡一带片麻状花岗岩进行了地球化学和年代学研究。结果表明:(1)麻栗坡一带片麻状花岗岩由三套酸性岩组成,分别为老城坡、南捞和团田片麻状花岗岩。通过它们的岩相学,岩石地球化学和年代学分析对比,这些片麻状花岗岩结构构造相似,地球化学特征相似,以及成岩年龄相近,唯一差别在于构造变形程度不同,推断这三套酸性岩很可能来自同一岩浆源区。(2)它们的Si O2含量介于69.94%~76.36%。全碱含量(K2O+Na2O)较高,变化于6.11%~8.31%。均属于过铝质高钾钙碱性S型花岗岩。大离子亲石元素Rb、K相对富集,Ba、Sr、P亏损明显;高场强元素U、Hf相对富集,Ti、Nb亏损。球粒陨石曲线总的分布规律呈弱右倾 V‖型。这些片麻状花岗岩总体具有S型花岗岩特征,部分数据显示具有I型花岗岩的特点,表明岩浆源岩可能来自早期大部分地壳物质混染地幔物质,经过后期地壳增厚而部分熔融的产物。(3)老城坡片麻状花岗ZK40-1b8样品LA-ICP-MS锆石U-Pb加权平均年龄为415.4±5.2Ma;老城坡片麻状花岗MLP156-Q21样品加权平均年龄为432.7±2.6Ma;团田片麻状花岗MPL133-Q14样品加权平均年龄为419.8±3.2Ma,属晚志留纪岩浆侵入的产物。(4)老城坡片麻状花岗岩(MLP156-Q21)εHf(t)值变化为-4.75~-10.52,两阶段Hf模式年龄TDM2分布于1771~2094 Ma;团田片麻状花岗岩(MLP133-Q14)εHf(t)值变化为-12.25~10.69,两阶段Hf模式年龄TDM2分布于728~2271 Ma,表明其岩浆源区主要以元古代地壳物质为主,成岩过程中有地幔物质参与,属于壳幔混源花岗岩。(5)麻栗坡一带片麻状花岗岩形成于同碰撞环境,广西运动发生时,云开地体与桂滇-北越地体相互作用,导致岩浆侵位于华南褶皱带。
[Abstract]:In order to study the formation, evolution and prospecting prospect of Song Chay dome granitic granites on the Sino-Vietnamese border. Geochemistry and geochronology of granitic granitoids in the northern end of the dome have been carried out in this paper. The results show that the granitic granites are composed of three sets of acidic rocks, one of which is the Laocheng slope. Through their petrographic, petrogeochemical and chronological analysis and comparison, these granitic granites have similar structures, similar geochemical characteristics and similar diagenetic ages. The only difference is that the degree of tectonic deformation is different. It is inferred that these three sets of acidic rocks probably come from the same magmatic source. (2) their Sio 2 content is between 69.94 and 76.36.The total alkali content of K 2O Na 2O is relatively high. All of them belong to peraluminous high-potassium calc-alkaline S-type granites. The large ion lithophile element Rbnk is relatively enriched in Bajiu Sr-P and the depletion is obvious. The relative enrichment of high field strength element Uttria HF is depleted. The general distribution pattern of chondrites is weakly right-dip V / V type. These granitic granites are characterized by S-type granites as a whole. Some of the data show that the magmatic source rocks may come from most of the early crustal materials mixed with mantle materials. A product of partial melting through the late thickening of the crust. The U-Pb weighted age of LA-ICP-MS zircon from granitic granitic ZK40-1b8 samples from Laocheng slope is 415.4 卤5.2 Ma. The weighted average age of Ramie granitic MLP156-Q21 samples in Laocheng slope was 432.7 卤2.6 Ma. The weighted average age of granitic granitic MPL133-Q14 samples is 419.8 卤3.2 Ma. It is a product of late Silurian magmatic intrusions. (4) the MLP156-Q21) 蔚 Hfttof Laichengpo granitic granitoids varies from -4.75 to 10.52. The age TDM2 of the two-stage HF model was distributed at 1771 Ma and 2094 Ma. The value of MLP133-Q14) 蔚 Hfttof granitic granitic granitoids in Tuantian is -12.2510. 69. The two-stage HF model age TDM2 was distributed at 72802271Ma. it indicates that the magma source area is mainly Proterozoic crustal material, and mantle material is involved in the diagenesis process. The granitic granitoids formed in the same collision environment in the Malipo area. When the Guangxi movement took place, the Yunkai terrane interacted with the Gui-Yunnan-North Vietnam terrane. The magma transgression is located in the South China fold belt.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P588.121;P597.3

【相似文献】