地幔熔融柱反演软件Calmantle1.0与云南腾冲地区新生代岩石圈厚度变化的初步讨论

基于前人提出的地幔熔融柱模型和反演方法,笔者编写了一个界面友好的应用软件Calmantle1.0。应用Calmantle1.0,用户可轻易获得玄武岩部分熔融源区的起止条件,包括温度、压力、深度、部分熔融程度等。文中介绍该软件的使用方法,并以腾冲新生代玄武质岩石为例,说明熔融柱反演的地球动力学意义。Calmantle1.0从收集的154个腾冲火山岩分析结果中筛选出两组(N2和Q3)有效数据,反演得到其部分熔融起止深度分别为99～79km和109～88km。结合现今岩石圈厚度(60km)和地质限定条件,提出腾冲地区新生代造山之后经历了岩石圈厚度从约110km→约79km→约110km→约88km→约60km的变化过程。进而认为这是近场应力场与远场应力场强相互作用的结果,腾冲地区的现代地壳变形主要受近场应力场的控制。

Mantle melting column software named Calmantle1.0and the preliminary discussion on the thickness variation of the Tengchong Cenozoic lithosphere

On the basis of the previously proposed mantle melting column model and its inversion method,we have designed an implication software Calmantle1.0 with friendly interfaces.Using this software,users can easily obtain the partial melting conditions of the source area at the initial and final stages,including temperature,pressure,depth,the degree of partial melting and so on.This paper is aimed at introducing the use of the software,and illustrating geodynamic significances of the melting column inversion on the Tengchong Cenozoic basaltic rocks as an example.The Calmantle1.0 has screened two valid groups(N2 and Q3) of data from 154 collected analysis of the Tengchong Cenozoic basaltic rocks,and obtained the initial and final depths of the partial melting columns which are 99 km and 79 km for N2 basaltic rocks and 109 km and 88 km for Q3 basaltic rocks,respectively.Combined with the current lithosphere thickness(~60 km) and the geological constraints,it is proposed that the Tengchong volcanic field has changed in lithosphere thickness from ~110 km → ~79 km → ~110 km → ~88 km → ~60 km after the Cenozoic orogenesis.Furthermore,it is believed that such lithospheric thickness variation resulted from the strong interactions between the far-and near-field stress fields,and that the modern crustal deformation of the Tengchong area is controlled mainly by the near-field stress.