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在渤海湾沿海低地地区获得1个30m的全取心机械钻孔(QX01孔),对样品进行了沉积岩石学分析、底栖有孔虫鉴定、硅藻鉴定和粒度分析,结合AMS 14 C和OSL测年,重建了研究区晚更新世以来的古河道充填及环境演化过程。结果显示QX01孔自下而上可以分为6段:(1)30~29.72 m,陆相洪泛沉积;(2)29.72~29.4m,海侵沉积,>43.5ka BP;(3)29.4~17.7m,砂质沉积物,河道填充沉积,37.9~29.7ka;(4)17.7~13.2m,沉积物由砂质变为黏土质,29.7~8ka,由河道填充转为浅湖沼环境;(5)13.2~5m,8~4ka,全新世海侵沉积,沉积环境由陆相转为海陆过渡相,6 000~5 750cal BP海侵达到最强,之后逐渐退出该区;(6)5m以上,洪泛沉积,约1.7ka至今。沉积环境与海面具有很好的响应,MIS 4或6阶段时,海面较低,河流下切,形成古河道,下切最深处位于现代高程为-24.2m。MIS3阶段早期时,海面上升,37.9ka河道开始填充,至29.7ka填充完成,对应高程为-11.8m。末次盛冰期至早全新世时为浅湖沼环境,沉积作用停止或速率非常低。随着末次盛冰期的结束,海洋作用增强,进入全新世海侵沉积阶段,8~4ka cal BP。之后,沉积作用停止,至1.7ka以来,随着河流作用的不断增强,该区变为河流控制的洪泛沉积为主。同时,发现了两次沉积间断,分别发生在末次盛冰期的低海面时期和4~2ka时的海水退出、河流沉积尚不充分时期。
A total 30 centimeter borehole (QX01) was drilled in the lowland area of Bohai Bay. Sedimentary petrology, benthic foraminifera identification, diatom identification and particle size analysis were performed on the samples. AMS 14 C and OSL dating, reconstructed the ancient river filling and environmental evolution since the late Pleistocene in the study area. The results show that the QX01 pore can be divided into 6 segments from bottom to top: (1) 30 ~ 29.72 m, flood deposition in the terrain; (2) 29.72 ~ 29.4 m, transgressive sediment,> 43.5 ka BP; (3) 29.4 ~ 17.7 m (4) 17.7 ~ 13.2 m, the sediment changed from sandy to clay, from 29.7 to 8 ka, and changed from river filling to shallow lacustrine environment; (5) 13.2 ~ 5m, 8 ~ 4ka. During the Holocene transgressive sediments, the sedimentary environment changed from continental facies to continental transitional facies, and the transgression of 6 000 ~ 5 750 cal BP reached the strongest and then gradually dropped out of this area. (6) Above 5 m, , About 1.7ka so far. The depositional environment has a good response to the sea surface. In MIS 4 or 6, the sea surface is lower and the river is undercut to form ancient river courses. The deepest undercutting is located at the modern elevation of -24.2m. In the early period of MIS3, the sea level rose, and the 37.9 ka river started to fill up to 29.7 ka filling, corresponding to elevation of -11.8 m. During the last glacial-early Holocene epicenospheric lacustrine environment, sedimentation stopped or the rate was very low. With the end of the last glaciation, the ocean enhanced and entered the stage of Holocene transgression sedimentation, 8 ~ 4 ka cal BP. Afterwards, sedimentation ceased. Since 1.7ka, with the continuous enhancement of river function, the area has become dominated by river-controlled flood deposits. At the same time, two sedimentary discontinuities were found, which occurred during the last glaciation in the low sea level and the seawater exit at 4 ~ 2 ka, respectively.