C14 Ages of sediment from the Rud Hilla delta area, Persian Gulf

Six sediment cores from the submarine delta of the Rud Hilla River in the northern part of the Persian Gulf consist of fine grained,homogeneous Holocene marls. The coarse (> 63 ~) fraction varies from 0.3 - 3.5 %. The cores are 2 - 4 m long and were taken in water depths of 8 - 56 m. In spite of the great similarity and homogeneity of the cored sediments, correspondence analysis (an extension of factor analysis) of the coarse fraction reveals the presence of four distinctive sedimentary facies: (1) a minerogenic facies, 10 km from the estuary; (2) an ophiuroidostracod facies near a lateral margin of the delta, 12 - 15 km from the estuary, (3) a benthic foraminiferal-molluskan facies, in the central part of the delta 20 km from the estuary, and near its seaward margin 120 km from the estuary, (4) a gastropod-epibiotic facies, in an area of relatively slow sedimentation on the border of the delta, 90 km from the estuary. A seventh core, taken near the seaward margin of the delta of the Rud Hilla River, penetrated homogeneous, aragonite-rich mud of late Pleistocene age. Correspondence analysis of the sand fraction of the Pleistocene sediments leads to the definition of two facies that can be readily compared with the facies identified in the Holocene cores.采自波斯湾北部鲁德希拉河（Rud Hilla River）水下三角洲的6个沉积岩芯，均由细粒均质的全新世（Holocene）泥灰岩组成。其中粒径大于63微米的粗组分占比为0.3%~3.5%。所有岩芯长度为2~4米，采集水深介于8~56米之间。尽管本次取芯获得的沉积物均质性强、相似度高，但通过对粗组分进行对应分析（correspondence analysis，因子分析（factor analysis）的扩展方法），仍识别出4种独特的沉积相：（1）矿质相，分布于距河口10公里处；（2）蛇尾类-介形类相，位于三角洲侧缘，距河口12~15公里；（3）底栖有孔虫-软体动物相，分布于三角洲中部（距河口20公里）及三角洲向海边缘（距河口120公里）；（4）腹足类-附生生物相，分布于三角洲边界沉积速率相对较慢的区域，距河口90公里。另有第七个岩芯采自鲁德希拉河三角洲的向海边缘，穿透了晚更新世（late Pleistocene）时期的均质富文石（aragonite）泥。对该更新世沉积物的砂组分开展对应分析后，定义出两种可与全新世岩芯中识别出的沉积相直接对比的沉积相。