湘西王村剖面寒武系花桥组浊积岩特征及其大地构造意义

湘西王村地区的寒武系代表江南斜坡相沉积序列，传统的下寒武统划分为杷榔组、清虚洞组；中寒武统划分为敖溪组、花桥组（下部）；上寒武统划分为花桥组（上部）、追屯组。其中，花桥组中浊流沉积发育，可识别出7次规模较大的浊流活动期，第一期浊积岩包括69个浊积序列，分别归属于11个副层序；第二期浊积岩包括37个浊积序列，分别归属于7个副层序。每个副层序的下部表现为近源浊积岩，上部表现为远源浊积岩，所代表的海水深度变化由浅变深。第一期浊流活动发生在海平面上升时期，形成三级层序的海侵体系域；第二期浊流活动发生在海平面较低、斜坡较陡时期，形成三级层序的低水位体系域。江南斜坡带中—上寒武世浊积岩频繁出现反映台地边缘深大断裂周期性活动强，断裂两盘升降差异运动显著。

Tectonic Significance and Sedimentary Characteristics of Turbidity Successions Within the Cambrian Huqiao Formation at Wangcun Section in the West Hunan, South China

Cambrian System at Wangcun section, west Hunan Province, represents typical sedimentary successions on the Jiangnan Slop Belt. Traditionally, the Lower Cambrian Series at the Wangcun section is divided into Balang Formation, Qingxudong Formation; the Middle Cambrian is divided into Aoxi Formation as well as the lower member of Huqiao Formation, and the Upper Cambrian Series is divided into the upper member of Huqiao Formation and Zhuitun Formation. Forming-stage of turbidity sediments within the Huqiao Formation can be attributed to seven long-term periods. The first turbidity succession in the Huqiao Formation includes 69 cycles that are attributed to 11 parasequences. The second turbidity succession in the Huaqiao Formation includes 37 cycles that are attributed to 7 parasequences. Lower part of!each parasequence consists of initiated turbidity sediments, and the upper part!of each parasequences consists of distal turbidity sediments. A gradual rise in sea level can be deduced based on the marine sediments within each parasequence. The first turbidity succession formed during the sea-level rising period consists of transgression system. However, the second turbidity succession deposited on the relatively steeper slope during the low sea-level period forms the low water system. The Lower-Middle Cambrian turbidity succession frequently deposited on the Jiangnan Slope Belt suggesting that periodic activities existed during the formation of deep-fault along the margin of carbonate Platform.