滇西腾冲地区滇滩A型花岗岩的年代学、地球化学及其构造意义  

Implications of the geochronology and geochemistry of Diantan A-type granites in the Tengchong area

作　　者：唐婉丽 许继峰[1,3] 陈建林[1,3] 谈荣钰 黄文龙[1,2] 

机构地区：[1]中国科学院广州地球化学研究所同位素地球化学国家重点实验室,广东广州510640 [2]中国科学院大学,北京100049 [3]中国科学院青藏高原地球科学卓越创新中心,北京100101

出　　处：《地球化学》2018年第1期1-13,共13页Geochimica

基　　金：国家重点基础研究发展计划(2015CB45260201);国家深部专项(2016YFC0600305);国家自然科学基金(41373035;41573024);中国地质大调查项目(DD20160024-06)

摘　　要：云南腾冲地区晚白垩世(81 Ma)滇滩花岗岩具有类似于典型A型花岗岩的地球化学组成特征,如高K_2O+Na_2O(6.37%~8.68%)和低Al_2O_3(最高为13.1%)、P_2O_5(<0.01%)含量,明显亏损Ba、Sr、Ti、Eu等元素;同时具有明显高的K_2O/Na_2O(除15DT-11为56.9,其余为1.51~1.58)、FeO/(FeO+MgO)(0.76~0.90)和10000Ga/Al(3.26~3.72)比值。另外,研究区A型花岗岩地球化学组成与实验岩石学研究结果相吻合,如具有较低的CaO(0.65%~0.78%)、Al_2O_3(12.40%~13.10%)和Mg O(0.11%~0.32%)含量等。滇滩花岗岩上述地球化学组成特征,很可能暗示其为英云闪长质或花岗闪长质原岩部分熔融的产物。结合青藏高原南部和东南部广泛发育的晚白垩世岩浆作用及区域构造背景,滇滩A型花岗岩很可能为陆-陆板块碰撞后因伸展作用引起的地幔物质上涌增温导致地壳熔融产生的一期重要岩浆活动。The Late Cretaceous （81 Ma） Diantan granites, developed in the Tengchong area of the Yunnan Province, have some affinities with typical A-type granites, such as high K20 ＋ Na20 concentration （6.37%-8.68%）, low A1203 （〈 13.1%） and P205 （〈 0.01%） concentrations, obvious depletions in Ba, Sr, Ti, Eu elements in multi- element patterns normalized to primitive mantle plots, and high K2O/Na2O （except 15DT-11 is 56.9, and the rest is 1.51-1.58）, FeO/（FeO ＋ MgO） （0.76-0.90）, and 10000Ga/A1 （3.26-3.72） ratios. In addition, the major element contents of Diantan granites are similar to the experimental petrology results of previous researches. The geochemical characteristics of the Diantan granites suggest that they probably resulted from partial melting of tonalitic or granodioritic material. The Diantan A-type felsic magmatism, combined with the widespread Late Cretaceous magmatism that occurred in southern and southeastern Tibet, imply that the Late Cretaceous magmatism developed in an extension setting during continental-continental collision, which was triggered by the upwelling mantle material.

关 键 词：晚白垩世 地球化学 A型花岗岩 伸展作用 滇滩 藏东南 

分 类 号：P588.121[天文地球—岩石学] P597.3[天文地球—地质学]