鄂尔多斯盆地西、南缘奥陶系滑塌堆积

鄂尔多斯盆地西、南缘中、上奥陶统发育有各种重力流沉积,其中含有巨大砾石或外来体.后者可呈不规则长园状和似层状,规模可达十至数十米,甚至百米左右.本文讨论了这种特殊沉积的岩性特征、层位和空间组合关系以及成因.认为它是一种滑塌堆积,它形成于拉张构造背景下的大陆边缘陡坡带,滑塌作用形成了大砾石和外来体,重力流是其搬运的载体.

Olistostrome in Ordovician System,Western and Southern Margin of Ordos Basin

Olistostrome of gravity flow are found in the Middle and Upper Ordovician in the western and southern margin of Ordos Basin, Some of great boulders, and allochthons as irregular long-cylinder or stratoid structure with ten to one hundres meters long are found in parts of the strata, as the allochthons are dishar-monious obviously with the host rock, it suggests that the orgins are different. The pefrdogic characters, stratigraphic horizon, the assembledge of rock and forming of olistostrome ard discussed. It proposed by the author that the olistostrome is formed on the steep gradient zones of passive continental margin of rifts, where great boulders and allochthons are produced by collapse and carried by gravity flows.