地壳岩浆底侵的地球物理判识模型构建  

Construction of geophysical identification model for crustal magmatic underinvasion

作　　者：李芃[1] LI Peng(Jincheng College of Sichuan University,Chengdu 611731,China)

机构地区：[1]四川大学锦城学院,成都611731

出　　处：《地球物理学进展》2020年第5期1682-1687,共6页Progress in Geophysics

基　　金：国家自然科学基金项目(61871405)资助.

摘　　要：当前研究多通过描述岩浆底侵作用内涵来判识岩浆底侵作用,缺少利用模型判断识别过程,导致判识效果较差,因此提出基于地球物理中凝聚态物理方法构建地壳岩浆底侵判识模型.以长江中下游地区为例,通过岩石学证据及地热学等证据,证明该地区存在地壳岩浆底侵现象,构建地壳岩浆底侵的地球物理判识模型.根据含水是否处于饱和状态及单斜辉石熔融状态类型,将地幔熔融百分数划分成三段.并根据具体深度积分熔融状态百分数,获取地壳岩浆底侵厚度.以此为基础采用静态流变本构关系计算岩石圈强度,判识岩浆底侵的热-流变效应.采用所提地球物理辨识模型分析得出:岩浆底侵厚度与温度扰动时间成正比,岩浆底侵厚度可控制温度扰动;冷却岩浆后,岩石强度不断增加,地壳岩浆底侵位置表现出脆性;地壳岩浆底侵岩石圈强度显著高于正常时刻岩石圈强度.通过实验对比分析得出,所提判识模型的判识时间短、稳定性优.为地壳岩浆底侵的地球物理判断与识别提供有利基础.At present,most studies are based on the description of the connotation of magma basement invasion,and the lack of model judgment and identification process leads to poor judgment and identification effect.Therefore,this paper proposes to build a crustal magma basement invasion judgment and identification model based on the condensed matter physics method in geophysics.Taking the middle and lower reaches of the Yangtze river as an example,it is proved that crustal magma basement invasion exists in this area through petrological evidence and geothermological evidence.According to whether the water content is saturated or not and the type of monoclinic pyroxene melting,the melting percentage of the mantle is divided into three sections.And according to the specific depth integral melting state percentage to obtain the crustal magma bottom penetration thickness.On this basis,the static rheological constitutive relation is used to calculate the lithospheric strength and identify the thermal-rheological effect of magma subsurface invasion.According to the geophysical identification model,the thickness of magma floor penetration is proportional to the time of temperature disturbance,and the thickness of magma floor penetration can control the temperature disturbance.When the magma cooled,the strength of the rock also increased,and the embrittlement appeared in the emplacement of the crustal magma.The lithospheric strength of crustal magma subsurface invasion is obviously higher than that of normal lithospheric strength.Through comparative analysis,it is concluded that the proposed judgment model has a shorter judgment time and better stability.It provides a favorable basis for geophysical judgment and recognition of crustal magma subsurface invasion.

关 键 词：地壳 岩浆底侵 地球物理 判识模型构建 凝聚态物理 热-流变效应 

分 类 号：P315[天文地球—地震学]