徐州地区新元古界赵圩组风暴沉积特征分析

徐州地区新元古界赵圩组地层在赵圩村出露良好，整体为一套碳酸盐岩沉积，岩性组合可划分为4 段：鲕粒灰岩段、风暴事件沉积段、叠层石段和白云岩段，其中叠层石段又划分为A 和B两个单元。剖面内部发育大量风暴沉积记录，并与正常沉积在垂向上互层叠置，整体具有向上频率变弱、规模变小的趋势。典型的风暴沉积标志包括丘状交错层理、粒序层理、冲刷- 充填构造、冲刷切削构造、砾屑灰岩层、生物礁丘截切现象等。文中划分出4 种风暴沉积序列类型，说明每种序列类型指示的古地理和古环境意义，以及在剖面上的分布组合特征。依据剖面岩性与风暴沉积的分布组合规律，认为赵圩组由下至上构成一个总体向上变深，而后又变浅的沉积序列，沉积环境演化依次为浅滩-近岸浅水潮下带-碳酸盐岩开阔台地-碳酸盐岩局限台地-深水斜坡-潮坪、泻湖，气候总体炎热干旱。风暴频发可能与沉积期本区所处的较低的古纬度有关。

Characterization of Tempestite Sediments of the Neoproterozoic Zhaowei Formation in Xuzhou Area, Jiangsu Province

The Neoproterozoic Zhaowei Formation in Xuzhou consists of 4 units, i.e., oolitic unit, tempestite unit，stromatolitic
unit and dolomite unit. The stromatolitic unit was subdivided into A and B parts. The tempestites, which abate from early to later
stages, alternate with non-tempestites in the vertical section. Some typical sedimentary symbols of tempestite sediments were
developed in this zone such as hummocky cross stratification(HCS), flush-filling structure, cut structure, organic reef-cutting
structures, calcrudites, graded bed and so on. Four kinds of tempestites sequences were summarized according to the vertical
sequence types, structures and sediment characteristics. The distribution of tempestites was also summarized. The discovery of
tempestites is helpful to interpret the sedimentary environment. According to the distribution of tempestites and the lithologic
characteristics, the authors suggest that the sedimentary environments the Zhaowei Formation were successively shoals- landward
shallow subtidal zone- open carbonate platform- restricted carbonate platform- tidal flat or lagoon and the climate during the
deposition was warm and arid. Frequent storms occurred due to the relatively low palaeolatitude during the deposition.