西拉木伦河断裂在松辽盆地下部的延伸

西拉木伦河断裂作为华北板块与西伯利亚板块的最终缝合线,其西段的展布较为明确,但其东段尤其是在松辽盆地下部的延伸一直没有定论.本文通过对松辽盆地西部边界嫩江-八里罕断裂、中央断裂构造性质的研究,证实它们都具有左行走滑剪切的特征,据此初步提出了西拉木伦河断裂在松辽盆地下部被嫩江-八里罕断裂和中央断裂左行错移的认识.结合已报道的松辽盆地基底高精度锆石年龄数据,松辽盆地南部重力异常特征、MT剖面以及地壳和岩石圈厚度特征,认为西拉木伦河断裂在松辽盆地下部沿开鲁-通辽-科尔沁左翼中旗-长春-线展布.

The distribution of Xar Moron River Fault under Songliao Basin

The Xar Moron River Fault is the final suture between the North China Plate and the Siberia Plate.The location of its western part has been well known,but the extension of its eastern part remains unclear and has aroused much controversy,especially concerning its location under the Songliao Basin.Based on field investigation along the western margin of the Songliao Basin(Nenjiang-Balihan fault) and previous researches on the Central Fault in the Songliao Basin,it is found that the Nenjiang-Balihan Fault and the Central Fault were strike-slip faults at the early stage.They displaced sinistrally the Xar Moron River Fault and made it extending in a staircase form west to east.Based on the available high precision age data from the basement of the Songliao Basin,the reinterpretation of the gravity anomaly and MT profile,the characteristics of the lithosphere and crustal thickness of the northeast margin and the neighboring areas of the North China Plate,the authors revealed the distribution of the Xar Moron River Fault under the southern Songliao Basin,which extends from Kailu,Tongliao,Horqin Zhuoyizhongqi to Changchun.