渤海湾西岸湾顶晚更新世——全新世年代地层序列与地磁极漂移  

Late Pleistocene——Holocene Chronostratigraphic Sequence and the Geomagnetic Polar Excursion on the West Coast of Bohai Bay

作　　者：赵长荣[1] J.Hus 阎玉忠[1] 王宏[1] 张金起[1] 

机构地区：[1]天津地质矿产研究所,天津市河东区大直沽八号路300170 [2]CentredePhysiqueduGlobe

出　　处：《地质调查与研究》2003年第3期183-192,共10页Geological Survey and Research

摘　　要：渤海湾湾顶海岸带BQ1、BQ2孔的磁性地层序列显示两孔分别在孔深27.0～30.8m和18.5～21.5m处存在地磁极漂移。BQ1孔光释光(OSL)测年表明该漂移距今15～25kaBP,与莫诺湖漂移的发生时间(23kaBP)接近。相应地,BQ2孔较前的漂移可能与哥德堡亚时相当。沉积学、古生物地层学、OSL和古地磁综合研究,建立了BQ1孔晚更新世以来的年代地层框架:上更新统下限73.53m,约123.9kaBP;全新统下限18.48m,(10.3±0.79)kaBP。上更新统上部陆相及海陆过渡相沉积物中18.48～34.15m的OSL年龄10.3～33.3kaBP,对应深海OIS2阶段;上更新统下部的海相沉积物(第三海相层)中66.65～73.53m的OSL年龄约11～124kaBP,对应OIS5e阶段。The magnetic stratigraphical sequence of the Boreholes BQ1 and BQ2, on the west coast of Bohai Bay, shows that an excursion exists at the buried depth of 27.0 ～ 30.8 m for BQ1 and 18.5 ～ 21.5 m for BQ2, respectively. Two OSL ages at the position, dated in the BQ1, are (15.26±0.86) ka BP and (25.61±1.14) ka BP. The Mono Lake existed at ～ 23 ka BP. Therefore, the excursion in BQ1 is close to the Mono Lake excursion. The converted-elevation of the excursion, recorded by BQ2, is higher than it is in the BQ1. As a result, the subchron corresponds with Gothenburg event in BQ2. On the other hand, the stratigraphy framework is given by OSL dating and palaeomagnetical measurement, based on the sedimentological and palaeobiostratigraphical studies. In BQ1, the lower boundary of Late Pleistocene is at 73.53 m, ～ 123.9 ka BP; the lower boundary of Holocene is at 18.48 m, ～ (10.3±0.79) ka BP. The upper part of Late Pleistocene is composed of the terrestrial deposits and transitional deposits as well from 18.48 m to 34.15m, 10.3 ～ 33.3 ka BP, corresponding to the Stage OIS2. The lower boundary of Late Pleistocene is marine facies, ie the Third Marine Bed at 66.65 ～ 73.53 m,11 ～ 124 ka BP,corresponding to the Stage OIS5e.

关 键 词：渤海湾 地磁极漂移 OSL测年 上更新统下限 

分 类 号：P534.63[天文地球—第四纪地质学]