四川龙门山冲断带中北段岩石圈结构研究

根据龙门山及其两侧的航磁和重力场特征,可将龙门山区的区域磁场分河四个区域;区域重力场分为三个区带。在此基础上,利用大地电磁测深和深部地震测深资料,结合地质分析,在平面上把龙门山区的地壳构造分为四个区,上地幔构造分为三个区;剖面上把岩石圈结构分为特征不同的五层。上述成果为龙门山冲断带成因机制的研究奠定了基础。

STUDY ON LITHOSPHERE TEXTURE OF LONGMEN MOUNTAINS THRUST BELT (CENTRAL-NORTH SECTION) IN SICHUAN PROVINCE

According to the processing and analysing of aeromagnetic and gravity data of Longmen Moun-tains thrust belt and its adjacent areas,the magnetic field of this region could be divided into fourzones:Sichuan Basin high magnetic anomaly zone,Longmen Mountains magnetic anomaly steep-chang-ing zone,Pingwu-Lixian negative magnetic anomaly maximum zone,Hongyuan-Maerkang low magne-tic anomaly zone.Regional gravity fields are divided into three zones.The authors pointed out that the one of Longmen Mountains is a positive harmonious anomaly zone.In application of electromagnetic sounding and deep seismic data accosiated with geological analysis,the crust structure horizontally could be divided into four regions(the sima gentle region of west Sichuan Basin,the sima slope region of Longmen Mountains,the sima depressed region of Songpan-Heishui and the sima gentle region of Ruerga-Hongyuan-Aba rigion)and the upper mantle structure into three regions(the mantle gentleslope region of west Sichuan Basin,the mantle steep slope zone of Longmen Mountains and the mantlegentle slope region of Songpan-Ganzi);the lithosphere texture into four layers in vertical(upper crustlayer,lower crust layer,upper mantle cover and the layer underlying the asthenosphere).The paper has revealed the feature of the lithosphere in Longmen Mountains thrust belt and laid afoundation for the studying the mechanism of this thrust belt.