美国东岸陆架沙脊沉积  

SAND RIDGE DEPOSITS ON EASTERN NORTH AMERICAN CONTINENTAL SHELF

作　　者：曹立华[1] 蒋楠[1] 庄振业[1] 刘臻[1] 

机构地区：[1]中国海洋大学海洋地球科学学院,青岛266100

出　　处：《海洋地质前沿》2013年第12期6-15,共10页Marine Geology Frontiers

基　　金：国家自然科学基金(40476032)

摘　　要：美国东岸，自纽约长岛经马里兰、新泽西直至弗罗里达基本属于沙坝渴湖岸，岸外的内、外陆架上分布一系列水下沙脊及脊间沙带、沙丘和沙波等次一级底形。按新泽西岸外20-80m水深处35个沙脊的统计，脊长约2～11km，宽约1～4km，长宽比界于2：1～3：1之间，与世界典型沙脊长宽比40：1比较，本区沙脊属于短轴浪控型，脊高约1～3m，或者更高。向NE10°～30°伸展，两坡不对称，上游坡平缓，下游坡较陡，约2．5°～7．0°。按34-48m水深处的“黄金沙脊”上的20余钻孔岩心分析和HC年龄测试，划分沙脊自下而上3层地层：9～11kaBP以前的平原陆相层；9—5kaBP的下部沙脊沙层；5kaBP以来的上部沙脊沙层。上部沙脊层不断向下游SE侧超越迁移，局部定位观测的沙脊迁移率为1～2m／a。A series of bedforms, such as subaqueous sand ridges, sand ribbons between ridges, sand dunes and sand waves is well developed on the inner and outer shelves along the east coast of the Unit-ed States from Long Island of New York, via Maryland, New Jersey to Florida, as a part of the la-goonal shore. Statistics show that there are 35 ridges at the water depth ranging from 20 to 80 meters off New Jersey. The ridges are about 2 to 11 km long, 1 to 4 km wide, with a length/width ratio be- tween 2 ： 1-3 ： 1. Comparing to length/width ratio of 40 ： 1 of the typical sand ridges in the world, they belong to the type of wave-dominated sand ridges with short axes. They are usually 1-3 m in height and stretching in the direction of NE 10°-30°. The ridges are asymmetric and the upstream slope is relatively gentle whereas the downstream slope is relatively steep with a dipping around 2. 5-7.0 According to the data from more than 20 drilling vibracores and ^14C measurements on the ＂For-tune Ridge＂ at the water depth from 34 to 48 meters, the sand ridges have a three-layered structure from bottom to top.. （1） continental plain facies before 9-11 ka BP; （2）lower ridge sand unit in 9-5 ka BP;（3） upper ridge sand unit since 5 ka BP. The upper layer of sand ridges now keep moving down-stream toward SE direction with a speed of 1-2 m/a determined by the local positioning observation.

关 键 词：美国新泽西 陆架沙脊 形态 地层 动态演变 

分 类 号：P936.21[天文地球—自然地理学]