石油与天然气地质 ›› 1982, Vol. 3 ›› Issue (1): 49-56.doi: 10.11743/ogg19820105

• 论文 • 上一篇    下一篇

陕西富平中奥陶统平凉组的深水碳酸盐碎屑流

梅志超, 陈景维, 卢焕勇, 李文厚   

  1. 西北大学地质系
  • 收稿日期:1980-11-06 出版日期:1982-03-25 发布日期:2012-01-16

DEEP WATER CARBONATE DEBRIS FLOW IN THE MIDDLE ORDOVICIAN PINGLIANG FORMATION OF FUPING,SHAANXI

Mei Zhichao, Chen Jingwei, Lu Huanyong, Li Wenhou   

  1. Department of Geology, Northwest University
  • Received:1980-11-06 Online:1982-03-25 Published:2012-01-16

摘要:

在陕西富平,中奥陶统平凉组中,发育有含巨大岩块的杂乱角砾石灰岩。这种石灰岩以其碎屑大小悬殊,排列紊乱,不同成因的石灰岩砾石混杂,巨砾和岩块呈漂浮状散布于较细的砾石之中为特征。杂乱角砾石灰岩呈席状夹在深水盆地相的页状石灰岩和薄板状石灰岩中,其内部缺乏层理,上下接触界限截然。这些标志证明,它们是深水盆地的海下碎屑流沉积。杂乱角砾石灰岩的碎屑物,主要为浅水台地边缘的碳酸盐岩和较深水斜坡的碳酸盐岩的崩解产物。

Abstract:

A chaotically brecciated limestone is found in the Pingliang formation of the Middle Ordovician in Fuping area,Shaanxi province.It occurs as bedded or sheet strata in,and in sharp contact with,the foliated and thinly tabular limestones.The fragments of it are highly varied in size and chaotically distributed,with the giant being 1?7m or larger.This limestone is lack of stratification and sorting,in which floating boulders and blocks are scattered in the matrix of finer clasts.These features show that it is of deep water carbonate sediments of debris.This limestone is dominantly composed of breccias of inner basin source.These clasts,formed by gravity sliding of consolidated or semiconsolidated sedimentary layers on slope of deep water basin,are transported by gravity and have accumulated on the margin of the basin floor.In the Middle Ordovician,the Fuping area was located on the northern margin of the deep water basin,where the maximum water depth was nearly one thousand metres.After the deposition of the Early Ordovician Majiagou formation,this area was subsided to form a deep water basin on the continental margin,by the tension fracturing of the back-arc basin on the northern side of the Qinling and Qilian Mountains.