MIS 3阶段以来河北黄骅北部地区海侵与气候期对比

依据渤海湾顶南侧、河北省黄骅北部地区4个钻孔岩芯样品微体古生物学、孢粉地层学研究以及沉积构造与地球化学背景分析,讨论了该地区MIS3阶段以来海侵期与气候期对比、海侵层中潮坪与浅海沉积单元的判别、沉积作用对孢粉和海侵记录的影响。依据海相世系微体生物出现确定的海侵层,可分为滨岸浅海～河口湾、潮坪、泻湖、分支河道、边滩、滨海低地、河间地～洪泛盆地等不同环境;含有孔虫或广盐海相介形类的地层,除了局部河流进积～退积作用,尚不能排除风、水、鸟的搬运,包括风暴潮的影响,并非是与海水体积变化有关的海平面变化;海侵层中的潮坪～浅海沉积单元才与海水深度有关,其他海水之上形成的地层所见海相微体生物,是地壳沉降背景下风暴潮和其他动力搬运的埋葬群,与海面变化无关,甚至仅是在东部沿海大平原构造沉降背景下河口位置向陆地移动的结果;海侵的发生与海域的扩大以及夏季风强度增大,物源区植被状况好转,造成海侵层出现乔木花粉,但是为异地埋藏。一般说来,还原背景下的沉积地层孢粉记录丰富;弱氧化～弱还原背景下的沉积地层孢粉相对较少,但也可能出现孢粉丰富的特例,氧化背景下沉积地层孢粉更稀少,全新世大暖期结束于约5kaB.P.。沉积学研究,包括对同期异相和突发事件沉积作用的理解,对晚第四纪研究是十分重要的。

SINCE MIS 3 STAGE THE CORRELATION BETWEEN TRANSGRESSION AND CLIMATIC CHANGES IN THE NORTH HUANGHUA AREA,HEBEI

Based on the study of micropaleontology,palynostratigraphy,as well as the analysis of sedimentary structure and geochemistry of core samples collected from a total of four drilling holes located on the north Huanghua area,Hebei Province,the south side of the end of Bohai Bay,the present paper discusses the correlation between transgressions and palaeoclimatic changes,the determination of nearshore sea and tidal flat deposits in the transgression bed,and the influence of sedimentation on transgression and spore-pollen records since MIS 3 stage.The transgression bed which had been determined by using the appearance of certain marine microbiota,can be subdivided into nearshore sea,estuary,tidal flat,lagoon,distributary,backswamp,costal low land,interfluve-fluvial basin and other environments.Stratum yielding foraminifera and euryhaline ostracoda could not simply be considered as transgression or sea-level change caused by sea-water volume change,as the effects of regional riverine progradation and retrogradation,transportation of wind,water,and bird,and storm could not be excluded.Only the tidal flat and nearshore sedimentary unit in the transgression bed has relation to sea-water depth.The marine microbiota occurring at the strata formed above sea-level might be the thanatocenose transported by storm and other power or be the result of the shifting of river mouth towards the land under the setting of earth crust subsidence on the East China Great Plain.With the happening of transgression,sea region expanse,and summer monsoon strengthening,the vegetation on the source area had flourishing,so that the arbor free pollen occurred in transgression bed,which are certainly allochthonous deposits.Generally,a stratum with reduction setting has more spore-pollens than those with oxidation setting,but there was a special example in the studied area with abundant spore-pollen records in an weakly oxidative stratum.The Megathermal phase of Holocene epoch had been ended at about 5kaB.P.The sedimentary research,including the understating of synchronous heteropic facies as well as abrupt event sedimentation,is important for the study of Late Quaternary.