晚更新世末至公元前7世纪的黄河流向和黄河三角洲

大约距今9600～8500a黄河在苏北北部入黄海.黄河口与其南侧的长江口相距100多千米.两条大河巨大数量的入海泥砂形成了黄河-长江复合三角洲.根据南黄海西部全新世海相沉积物厚度变化、苏北响水县陈家巷QCA孔沉积序列、阜宁以南、泰州以北里下河洼地早全新世沉积序列及苏北沿岸砂脊的物质组成判断,距今8500a左右黄河向北流注入渤海,距今8500～7000 a海面上升过程中没有形成黄河水下三角洲,距今7 000 a黄河三角洲又开始形成.

The Huanghe River course and delta from end of Late Pleistocene to the 7th century BC

The Huanghe(Yellow)River course shifted from entering the northern Huanghai(Yellow)Sea to entering the southern Huanghai Sea at the northern part of North Jiangsu Province approximately in 9 600 a BP and continued to enter the southern Huanghai Sea to 8 500 a BP.The river mouth was some 100 km distance from north of the Changjiang River mouth.The huge sediments carried by the two large rivers made the Huanghe River-Changjiang River compound delta to be formed in this period.Then,the Huanghe River shifted to north and entered the Bohai Sea.This is inferred with the following facts:southw ard bending of the isopach of the postglacial marine sediments of the nearshore depocenter in the southern Huanghai Sea,the sedimentary sequences of drill hole QC4 and some sections,and the characteristics of the coastal ridges in North Jiangsu Province.These coastal ridges are mostly composed of non-biogenic fine and middle sands.It is much different from composition of the shell ridges being mainly composed of molluscan shells and their fragments on the west coast of the Bohai Sea,where is the abandoned Huanghe River Delta area.In 8 500~7 000 a BP,the west coastline of the Bohai Sea retreated for tens kilometers,the Huanghe River channel free shifted and the fine sediments carried into the Bohai Sea by the Huanghe River were resuspended,transported and reworked into the shallow marine deposits.The Huanghe River subaqueous delta could not be formed in this period.The Holocene Huanghe River Delta has been formed since 7 000 a BP, when the sea level rise decelerated and close to the stable level.