东秦岭岩石圈热流变学结构初探  

A preliminary study on the lithospheric thermal-rheological structure of eastern Qinling orogenic belt

作　　者：程顺有[1] 张国伟[1] 刁博[1] 郭安林[1] 于香妮[1] 

机构地区：[1]西北大学大陆动力学教育部重点实验室/地质学系,陕西西安710069

出　　处：《西北大学学报（自然科学版）》2005年第5期601-605,共5页Journal of Northwest University（Natural Science Edition）

基　　金：国家自然科学基金重点资助项目(4023404149732080)

摘　　要：目的研究秦岭造山带的岩石圈流变学结构以探索其地球动力学意义。方法通过岩石圈温度结构约束,计算了岩石圈流变学结构。结果秦岭北半部的后陆冲断褶带和厚皮叠瓦逆冲带的莫霍界面温度为305℃,以冷地温、厚岩石圈和流变分层不明显的c模型为特征;南秦岭莫霍界面平均温度642℃,最高达826℃,具有显著的热地温、薄岩石圈和中下地壳及其上地幔顶部强烈流变的H模型特点。结论在后造山阶段,北秦岭是华北和扬子二地块相向向秦岭造山带陆内俯冲的前锋会聚区域,现今处于以岩石圈加厚为主、拆沉作用初始发动的共存状态;南秦岭可能在地幔柱作用下发生新的拆沉作用和部分底侵作用,其轴部区域的地壳内现今存在部分熔融,壳-幔之间正在进行物质、能量(热传导和热对流方式)等的再循环。Aim To study lithospheric rheological structure for exploring geodynamics. Methods Lithospheric theological structure has been inverted by lithospheric temperature structure constraint. Results The lithospheric thermal rheological stratification structures in eastern Qinling orogen are different features from each other with different tectonic units： Hinterland fault-bounded fold zone （HLZ） and North Qinling thick-skinned imbricated thrust zone （NQZ） in northern half part of the Qinling, with temperature 305~ for Moho boundary, are characterized by ＂cold＂ geothermal, thickened lithosphere and c-model with rheological stratification structure; but South Qinling （SQL） , with mean temperature 642℃ and highest temperature 826℃ for Moho boundary, has obvious features with H-model of “hot” geothermal, thinned lithosphere and intensive rheological behavior within moderate-lower crust and top of upper mantle. Conclusion Since post-orogenesis the NQZ, being convergent frontal region of continental subduction beneath the Qinling orogen by both North China craton （NC） and Yangtze craton （YZ）, is in coexistence period for dominant the thickened lithosphere and an initial delamination and the SQL, probably under pluming, is been developing new delamination and underplating and partial melting within the crust in its axel area and recycling for mass and energy （ in the forms of heat transfer and convection） between the crust and mantle.

关 键 词：秦岭造山带 岩石圈流变学结构 拆沉作用 大陆动力学 

分 类 号：P314[天文地球—固体地球物理学]