滇西腾冲更新世粗面安山岩Ar-Ar年代学、地球化学特征及其构造意义

发布时间：2019-05-08 04:12

【摘要】：腾冲芒棒地区广泛发育新近纪以来的火山岩,本文首次对该区粗面安山岩进行的高精度40Ar/39Ar同位素定年,其坪年龄分别为2.1±0.1Ma和2.0±0.1Ma,代表其喷溢时代为早更新世。岩石地球化学特征研究显示,粗面安山岩属高钾钙碱性系列,富集大离子亲石元素、亏损高场强元素,具有弧火山岩与大陆板内火山岩的双重属性,推测其形成于后造山环境。综合研究表明,腾冲地块更新世火山岩的形成与印度-欧亚板块俯冲-碰撞造山隆升后的伸展垮塌、富集地幔部分熔融作用密切相关,而印支陆块向东南逃逸以及腾冲弧形走滑断裂带(龙川江断裂带、大盈江断裂带)的活化促使了该期火山岩的喷发与侵位。
[Abstract]:Volcanic rocks have been widely developed since Neogene in the Mangan area of Tengchong. For the first time in this paper, the high-precision 40Ar/39Ar isotope dating of the trachyandesite in this area has been carried out with the flat ages of 2.1 卤0.1Ma and 2.0 卤0.1 Ma, respectively. Represents its spilling age as the early Pleistocene. The study of petrogeochemical characteristics shows that the rough andesite belongs to high potassium calc-alkaline series, rich in large ion lithophile elements, depleted in high field strength elements, and has the dual attributes of arc volcanic rocks and continental intraplate volcanic rocks, which is presumed to be formed in the post-orogenic environment. The comprehensive study shows that the formation of the Pleistocene volcanic rocks in the Tengchong block is closely related to the extensional collapse and partial melting of the enriched mantle after the subduction-collision orogenic uplift of the India-Eurasia plate. The escape of the Indo-Chinese continental block to the southeast and the activation of the Tengchong arc strike-slip fault zone (Longchuanjiang fault zone and Da Yingjiang fault zone) contributed to the eruption and emplacement of the volcanic rocks in this period.
【作者单位】：福州大学紫金矿业学院;中国地质大学地球科学学院;贵州省地质调查院;
【基金】：国土资源部深部探测技术与实验研究专项课题(201011060)资助
【分类号】：P588.144;P59

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