哈尔滨荒山剖面第四纪地层研究

Quaternary Stratigraphy of the Huangshan Section in Harbin

哈尔滨荒山剖面是东北地区第四纪典型剖面,因缺乏绝对年龄数据,关于其地层划分及时代还有不同认识.对荒山剖面进行了系统的磁性地层学研究,并与AMS14C、OSL等年代学数据相结合,重新厘定了荒山剖面第四纪地层的年代框架.结果表明,荒山剖面记录了Matuyama负极性时晚期至Brunhes正极性时的沉积,B/M界线位于剖面下部46.7 m,剖面起始沉积年龄早于0.90 Ma.根据AMS14C和OSL年龄确定了全新统和上更新统的底界,对第四纪岩石地层单位的分层标志及顶、底年龄进行了分析,确定第四纪各个岩石地层单位的时代分别为:坦途组的年龄为~12 ka BP,顾乡屯组的年龄为12~79 ka BP,哈尔滨组的年龄为79~138 ka BP,上荒山组的年龄为138~580 ka BP,下荒山组的年龄>900 ka BP.据此建立了荒山剖面第四纪地层系统,为区域地层对比提供依据.

The Huangshan section in Harbin is considered as a standard Quaternary sedimentary sequence for terrestrial strata in Northeast China.Due to the lack of absolute age data,there are different results about its stratigraphic division and the chronostratigraphy.In this paper,a detailed magnetostratigraphic investigation,coupled with AMS14 C,OSL and other chronological data was carried out on the Huangshan section.The chronological framework of Quaternary strata of the Huangshan section is redefined.The results show that the magnetic polarity stratigraphy includes late Matuyama negative polarity chron to Brunhes positive polarity chron in the Huangshan section.The B/M boundary is at 46.7 m in lower part of the section,and the initial deposition age of the section is earlier than 0.90 Ma.The Holocene and Upper Pleistocene lower boundaries are determined according to AMS14 C and OSL ages.The sequence of Huangshan section comprises in chronological order the Xiahuangshan,Shanghuangshan,Harbin,Guxiangtun and Tantu Formations.The age of each lithostratigraphic unit in the Quaternary is determined as follows:the Xiahuangshan Formation is deposited earlier than 900 ka BP;the age of the Shanghuangshan Formation is 138-580 ka BP,that of the Harbin Formation is 79-138 ka BP,that of the Guxiangtun Formation is 12-79 ka BP,and the age of the Tantu Formation is^12 ka BP.The results provide new data for the Quaternary stratigraphic system of Huangshan section,and the division and correlation of Quaternary strata in Northeast China.