黔东北地区寒武系清虚洞组钙质风暴岩及其地质意义

在黔东北铜仁-江口地区下寒武统清虚洞组下部发育一套特征典型、序列特殊的钙质风暴岩.该风暴沉积的底面侵蚀构造清楚,板片状泥晶灰岩砾石呈菊花状排列,发育丘状交错层理、负载构造、递交层理和小波纹层理等沉积构造,为典型的浅海风暴岩.该风暴沉积序列的最大特点是含有大量钙质鮞粒.另外,不同的、类似于近源和远源的风暴沉积序列出露于同一剖面的相邻层位,可能反映了风暴登陆路径或者风暴流强度的差别.该风暴沉积的发现,对建立与黔中和湘西北同期地层的沉积学对比剖面、探讨风暴沉积模式的空间变化具有重要意义.

Calcareous Tempestite from the Cambrian Qingxudong Formation in Northeastern Guizhou Province and Their Geological Implications

This paper describes unique succession of calcareous tempestite from the Early Cambrian Qingxudong Formation,northeastern Guizhou Province.Typical depositional structures of tempestite,such as radically arrangement of plate-like micrite gravel,hummocky lamination,load structure,grading bedding and ripple bedding are presented in the succession,indicating its accumulation in an offshore environment.Different from other storm deposits,carbonate ooids are presented in the basal part of some storm deposits,commonly as dominant component with some randomly scattered micrite pebbles.Sequence with features of proximal storm deposits associates closely with sequence with features of distal storm deposits at the Longtangwan section,possibly resulting from differences in strength of storm fluids or in landing path of storm fluid.Comparisons of the sequence with those reported from the Lower Cambrian of northwestern Hunan Province as well as Lower Cambrian ooid banks of central Guizhou Province would be of much implication.