甘肃天祝斜壕地区上奥陶统远源钙质风暴岩的发现

甘肃天祝斜壕地区上奥陶统斯家沟组灰泥岩薄互层段和斜壕组黑色页岩段中发育一种间隔性（数十厘米至数米）出现的薄层（数厘米至十几厘米）浅灰色─灰白色的泥─微晶灰岩。其内部往往发育丘状、波纹伏、卷曲优等层理，层面多具波状起伏，底面可见小型槽模、沟模等，并且预底发育属Ｃｒｕｚｉａｎａ－Ｚｏｏｐｈｙｃｏｓ混合相的遗迹化石。其成因是风暴作用形成的，属产于浅海陆架较深水地带的远源钙质风暴岩。

Discovery of distal calcareous tempestites of upper ordovician age from Tianzhu, Gansu

Thin-bedded (a few to tens of centimeters thick) light gray to greywhite micritic limestones are developed intervally (tens of centimeters to a few meters) in the limestone and mudstone interbed of the Sijiago Formation and black shale of the Xiehao Formation which occur in the Ordovician of the Xiehao region of Tianzhu, Gansu. Hummocky, ripple and curved beddings are common in them.On the surfaces of them exist some small flute casts and groove casts. On the top and bottom surfaces of them are trace fossils of Cruziana-Zoophycos mixed factes.They originated from tempest and are the distal calcareous tempesitites formed in the deep parts of shallow-sea shelf.