松科1井南孔嫩江组磁性矿物组合特征及其意义  

Magnetic records from the Nenjiang Formation of core SK-1s and their implications

作　　者：李海燕[1] 周庭红 张世红[1] 刘光泓 吴怀春[1] 杨天水[1] 赵坤玲[1] 

机构地区：[1]中国地质大学生物地质与环境地质国家重点实验室,北京100083 [2]北京大学地球与空间科学学院,北京100871

出　　处：《地学前缘》2017年第1期143-153,共11页Earth Science Frontiers

基　　金：国家重点基础研究发展计划"973"项目(2012CB822002);国家自然科学基金项目(41422202;41576062)

摘　　要：对松辽盆地松科1井南孔嫩江组(嫩一段上部至嫩二段下部,972.46~1 060.24m)开展了岩石磁学研究,发现其顶部层段(A段,972.46~979m)的磁化率和剩磁均受控于磁铁矿,中间层段(B段,979~1 025m)和下部层段(C段,1 025~1 060.24m)的磁化率主要受控于顺磁性矿物,但其主要携磁矿物仍是少量的磁铁矿。A段沉积物中的磁铁矿含量最多,且粒度最粗;B段沉积物中的磁铁矿含量最少,粒度中等;C段沉积物中的磁铁矿含量中等,粒度最细。松科1井南孔嫩江组不同层段沉积物中磁性矿物组合的不同特征揭示了还原成岩作用对沉积物的影响、盆地的构造抬升运动和古气候变化。首先,不同层段沉积物受到还原成岩作用不同程度的影响,A段沉积物几乎不受影响,B段和C段沉积物均受到较强的影响,从而形成A/B界线。其次,磁学参数的周期性小幅波动记录了松辽盆地古气候的周期性变化。最后,B/C段界线处磁学参数的突然快速变化可能与松辽盆地东部逐渐抬升所引起的物源变化(由南北向转变为东西向)有关。Rock magnetic records have been achieved from the Nenjiang Formation of the Songke-1south core（SK-1s）in the Songliao Basin（972.46-1060.24 m）.According to the magnetic records,this sequence is divided into three sections,termed A（972.46-979 m）,B（979-1025 m）and C（1025-1060.24 m）,respectively.Magnetic susceptibility（MS）and remanence of section A are both controlled by magnetite;while MS of sections B and C is controlled by paramagnetic minerals and their remanence is mainly carried by magnetite.Among the three sections,the concentration of magnetite of section A is the most and that of section B is the least;while the magnetite particles of section A are the coarsest and those of section C are the finest.The magnetic records of the Nenjiang Formation from SK-1shas deciphered the information of the uplift of the basin and the paleoclimatic changes of this area,although reductive diagenesis plays an effect on the sediments of sections B and C and thus produces the A/B boundary.On the one hand,the fluctuation of the magnetic parameters have recorded the periodical paleoclimatic changes.On the other hand,the abrupt variation of the magnetic parameters at the B/C boundary may be related to the alteration of detrital provenances resulting from the uplift of the eastern basin,from south-north to east-west.

关 键 词：松科1井南孔 嫩江组 岩石磁学 还原成岩作用 湖平面变化 物源 

分 类 号：P534.53[天文地球—古生物学与地层学] P539.3[天文地球—地质学]