江苏小庙洪牡蛎礁的地貌-沉积特征

利用卫星影象和野外实地勘察资料对江苏小庙洪牡蛎礁的地貌-沉积特征进行分析。结果表明，该牡蛎礁发育在强潮淤泥质潮坪上，造礁牡蛎主要是近江牡蛎和长牡蛎，表层的鲜活牡蛎为褶牡蛎。牡蛎礁区海水属盐度较高(27—30)的半成水，含沙量较大，为0．2—0．3g／L。活体牡蛎堆积体顶面高于周围潮间下带滩面1．0—1．5m。潮流较强，多在0．5—2．0m／s。海岸剖面可分为4个带，即礁后潮间带、潮沟、礁体生长带及礁前斜坡带。由于处于海岸侵蚀段，礁后潮坪缺失潮上带和大部分的潮间上带。礁后潮坪主要以粗粉砂为主，礁后潮沟冲淤变化较大，故礁体生长带时而为一沙洲，时而又与岸滩相连。礁体生长带分布在潮间下带，可看到独立的斑状礁体、带状礁体和大面积环状礁体群。环状礁的微地貌可以划分为礁塘(泻湖)、塘口和塘沟、塘口三角洲、礁墙和礁平台等。

THE GEOMORPHOLOGY-SEDIMENTOLOGY CHARACTER OF OYSTERREEF IN XIAOMIAOHONG TIDAL CHANNEL, JIANGSU PROVINCE

The living oyster reef in Xiaomiaohong tidal channel which lies off the north coast of Haimen, Nantong city, Jiang-su Province, has been largely ignored by researchers. It grows in the macrotidal mudflat. Based on analysis of satelliteimages,the area of the reef region is 3.5 km². The oysters here are mostly Ostrea rivalaris Gould and Crassostrea gigas, the living oyster reef is Ostrea plicatula Gmelin. The seawater here has a high salinity, belongs to half-salty and has greater sediment concentration. The top of the accumulated body of the living oyster reef is 1.0-1.5 meter higher than the nearby lower intertidal flat. The tidal current velocityis commonly 0.5-2.0m/s. The coastal cross-section from the coast to the sea is composed of 4 zones, the intertidal flat behind the oyster reef, the tidal creek, the growth zone of the oyster reef body and underwater slope in front of the oyster reef. Due to erosion, the tidal flat at the back of the oyster reef is short of the supratidal zone and of the greater part of upper intertidal zone. The tide flat behind the oyster reef is mostly composed of coarse silt. The erosional orsiltational state of the tidal creek changes significantly, hence, the oyster reef zone is sometimes abank in the Xiaomiaohong tidal channel, but it issometimes joined to a coastal mudflat. The litter fleck-shapedreef body, the parallel-bilted one, and the greater ringed one canbeen seen in the lower intertidal flat. The micromorphology in the area of reef body can been subdivided intothereef pond( lagoon) , pond entrance and pond creek, pond creek delta, reef wall and reef terrace, etc. Due to the exility and speciality of intertidal oyster reefs, the authors suggest immediate researchin to this oyster reef. The priority should be biological and ecologicalresearch. The interactional process between oyster, oyster reef and the coastal zone, the influence of the oyster reef to the tidalflat dynamics and the reciprocity and feedback mechanis mbetween the oyster reef and seawater should also beareas of researchconsideration. It is important to discover the tidal level corresponding to the oyster reef top, the floor depth and oyster stickinglocation model. This information will provide a new approach to research Holocene sea level change.