塔里木盆地西北缘震旦纪风暴岩成因探讨

本文首次论证了塔里木盆地西北缘震旦纪风暴岩的存在。就风暴岩的结构特征、沉积序列、成因模式作了探讨。震旦纪风暴岩具有底面侵蚀-充填构造、无规则排列的砾屑灰岩层、粒序层及丘状层理,以及水平纹理和纹状交错层。风暴岩可分为二种类型:钙屑风暴岩为强的风暴产生的风暴浪和风暴流而形成,由-套砾屑灰岩及泥灰岩、泥岩组成;砂屑风暴岩是由强度相对较弱的风暴离岸回流将风暴高峰悬浮起的砂屑物带到浪基面以下的地方沉积而成,由砂岩、粉砂岩及粉砂质泥岩组成。

Discussion on the Origin of the Sinian Tempestites in the Nwrthwestern Margin of Tarim Basin

Sinian tempestites is proved for the first time in the northwestern margin of the Tarim Platform, which occur in the upper sub-formation of the Sugiterblack Formation of Upper Sinian System (simply called "upper sub-formation" land can be divided into two types: l.Calcarenaceous tempestites which lie in the nearshore-deposited clastic rocks in the middle and lower parts of the upper sub-formation. 2.Sandy tempestites lie in the shallow-shelf-deposited carbonate at the top of the upper sub-formation. The calcarenaceous tempestites consist of calcirudites. calcisiltites. calcarenites. oolitic limestones and residual oolitic limestones, calcarenaceous sandstones, calcilutites and mudstones. The calcirutes are abundant with sharp eroded boundarys at the bottom and many multi-orientation marks. Scour and fill structures, graded beds and a variety of hummocky cross-stratifications are usually found in the typical tempestites. The synthetic idealized tempestite sequence is composed of seven divisions above the erosional base. They are coarse-grained calcirudite division A (winnowed lag), graded division A. massive dividion B. hummocky cross-stratification division C. planar parallel lamination division D. ripple cross-lamination division E and pelitic division F from the bottom to the top. In comparison with the synthetic idealized tempestite sequence, the sectional structures may be divded into 12 types of quasi-complete, incomplete and complex sections and 9 of which occur in the calcarenaceous tempestites. They represent different stages of storm development controlled by storm intensity, the way of storm moving and current effect, duration of storm and depth of sea water.