由沉积物中准同生构造的褶皱展平试验确定沉积剩磁固化深度

上新世湖心相页岩中准同生构造的褶皱展平试验揭示,这套沉积物中的剩磁固化于这些准同生构造形成之后,固化深度大于10-15cm。这一事实与模拟实验结论的之间矛盾表明,由于天然过程的进行速率慢得无法与实验室过程比拟,天然沉积物中沉积后碎屑剩磁的作用要比模拟实验的绪论强得多。将模拟实验得出的关于磁性颗粒重新排列条件的定量结论简单地外推到天然过程是不适当的。任何关于沉积物获得剩磁的模型都必须接受以天然过程为基础的检验,仅有实验室内的模拟试验是很不够的。

Determination of Post-depositional Remanent Magnetization (PDRM) Lock-in Depth by Flod Test on Syndepositional Fold Structures

Fold test was carried out with syndepositional fold structures in a sequence of Pliocene varved marls of lake centre facies. It revealed that the magnetization preserved in this sedimental sequence was fixed after these microfold structures formed. In other words, the PDRM remanent magnetization lock-in depth is larger than 10-15 cm, the thickness of the individual limbs. This fact is contradictory to the conclusions from the molding tests. It most probably results from the fact that the rate of the processes occured in nature is incomparably lower then those of the processes in the laboratory. Consequently, as to the final accumulated effect of the mobility, the possibility of reorientation for magnetic grains in natural sediments is much larger than that seen by molding tests. Obviously, it is not suitable to extrapolate the critical conditions derived from molding tests to the natural situation. Any theoretical model on acquiration of remanent magnetization should be tested by natural process finally.