二连盆地白音查干凹陷下白垩统震积岩的发现及其地质意义

The Discovery of Seismites in the Lower Cretaceous of Baiyinchagan Depression,Erlian Basin and Its Geological Implications

二连盆地白音查干凹陷下白垩统钻井取芯中发现有变形和开裂两类特殊地质现象。同沉积塑性变形和碟状构造属于变形,微断层、网状裂缝、砂岩岩脉、角砾岩为开裂。这些地质现象具有震积岩的特征,多由外界振动引发。变形多发生在沉积物未固结—半固结阶段,开裂发生在沉积物成岩后。微断层、网状裂缝和砂岩岩脉形成于拉张应力作用下。这些特殊地质现象多出现在腾格尔组和都红木组一段,而且从下往上,由开裂向变形演化。这与当时区域伸展构造背景和地震、构造活动有关,地震、构造活动较为强烈时容易产生开裂现象,地震、构造活动较为微弱时容易产生变形。

In the lower Cretaceous drilling cores of Baiyinchagan Depression, Erlian Basin, two types of special geological phenomena are discovered, of which the syn-depositional plastic deformations and saucer-shaped structures belong to deformation, and the micro-faults, net-shaped fractures, sand dykes and syn-depositional breccia belong to cracking. The special geological phenomena were initiated by the outside viberation and are characterized by seismites. The deformation phenomena were mostly formed during the non-solidification-semisolidification phase, and the cracking often came into being after the diagenesis. The micro-faults, net-shaped fractures and sand dykes were attributed to the extensional stresses. The special geological phenomena were abundantly distributed in the Tenggeer Formation and Du 1 Member of Duhongmu Formation, and they gradually evolved from cracking into deformation upwards along the vertical direction. The research also showed that they were related to the tectonic background of regional extension and the activities of palaeo-fauhs and palaeo-earthquakes, of which the intensely active faults and strong earthquakes often caused cracking and the gently active faults and weak earthquakes mostly caused deformation.