摘要
对采于四川北部江油 北川地区 (31.4°N ,10 4 .3°E)下石炭统 39个采点的 334块灰岩标本进行了较为系统的古地磁学研究 ,结果表明 ,标本中剩磁方向具有明显的双分量特征 ,低温 (10 0～ 30 0℃ )分量在地理坐标系下与现代地磁场方向基本一致 ,且不能通过褶皱检验 ,应是现代地磁场的重磁化 ,中温 (30 0～ 4 80℃ )反极性分量在地层坐标系中具有高负倾角的特征 ,其形成可能与早侏罗世岩层的褶皱弯曲有关 .
An intensive paleomagnetic investigation has been carried out on the Lower Carboniferous limestone near Jiangyou(31.4°N,104.3°E) in the hope of identifying the Early Carboniferous paleomagnetic pole. In general, two magnetic components can be isolated after the removal of a soft viscous overprint by temperature step 100℃ from all samples studied. The low temperature (100～300℃) magnetic component is close to the present day Earth field and fails fold test, which corresponds to a recent overprint. The reversed middle temperature (300～480℃)component passes fold test and yields a pole position (305.9°E, 50°S, d p=6.8, d m=7.3, paleolatitude:65.4). On the basis of paleomagnetic data and geological evidences, we suggest that the reversed middle temperature component is probably acquried at the time of the Early Jurassic folding in the west part of South China Block.
出处
《地球物理学进展》
CSCD
2002年第3期406-413,共8页
Progress in Geophysics
基金
国家自然科学基金项目 (批准号 :495 2 5 40 6
40 0 740 17)资助
