莱州湾地区滨海黄土研究  

Study on Coastal Loess in the Laizhou Bay

作　　者：徐建国[1] 张涛[1] 徐华[1] 张卓[1] 祁晓凡[1] 纪汶龙[1] XU Jian-guo;ZHANG Tao;XU Hua;ZHANG Zhuo;QI Xiao-fan;JI Wen-long(Shandong Institute of Geological Survey,Ji'nan 250013,China)

机构地区：[1]山东省地质调查院,山东济南250013

出　　处：《海洋科学进展》2019年第1期43-54,共12页Advances in Marine Science

基　　金：中国地质调查局地质调查项目--山东半岛蓝色经济区地质环境调查评价(1212011220001);山东1:5万海沧幅(J50E018023);山东1:5万昌邑幅(J50E019022);山东1:5万侯镇幅(J50E019020);山东1:5万小清河口幅(J50E017021)环境地质调查(12120114033801)

摘　　要：莱州湾地区是山东半岛黄土的主要分布区,该区黄土按形成时代、岩性岩相的不同分为羊栏河组、大站组,分属于中更新统和上更新统,沉积相分别为风积相和冲洪积相,其中大站组黄土的形成和分布与晚更新世古气候、古地理环境密切相关。通过对莱州湾地区晚第四纪地层结构、岩相和第四纪测年资料的分析,可知大站组黄土垂向上分为上、下两段,分别形成于末次冰期的海洋氧同位素MIS2和MIS3b阶段。大站组黄土上段垂向上位于第Ⅰ,Ⅱ海侵层之间,分布面积较小,主要位于研究区南部黄土埠分布区;下段垂向上位于第Ⅱ海侵层的两个海相层之间,分布面积较大,地表未见露头。在岩性上,大站组黄土上、下段在粒度组成、物理力学性质上存在明显差异,反映出在沉积时间上的较大差距。对不同地貌区大站组黄土的粒度组成进行了对比,发现莱州湾南岸平原区黄土颗粒明显较莱州湾东岸丘陵区黄土粗,显示出两者在沉积方式上的不同,前者主要是以地面跳跃或风沙吹扬的方式堆积形成,后者则主要是以在空气中悬浮搬运的方式堆积而成。最后对研究区黄土的成因进行了分析,大站组黄土的空间分布、岩性、微体古生物特征均表明,黄土的物源为渤海陆架古海床干燥的晚更新世晚期海相沉积土,属于风成堆积物。The Laizhou Bay area is the main distribution area of loess in the Shandong Peninsula. Based on their forming age, lithology and lithofacies, the loess of the area can be divided into Yanglanhe formation and Dazhan formation, which belong to Middle Pleistocene aeolian and Upper Pleistocene alluvial-diluvial sedimentary facies, respectively. The formation and distribution of Dazhan formation loess was close related to paleoclimate and paleo-geographic environment during Late Pleistocene. This study analyzed Later Quaternary stratum structure, lithofacies and Quaternary dating of Laizhou Bay area, and divided vertically the Dazhan formation loess into upper section and lower section, which were formed during Marine Isotope stage 2 (MIS2) and Marine Isotope stage 3b (MIS3b) of the last glacial period, respectively. The upper section of Dazhan formation loess (with small area) locates between transgression stratum I and II vertically, and mainly distributes at Huangtubu at south of the study area. The lower section of the formation (with a large area) locates between two marine beds of transgression stratum II. Lithologically, these two sections have obivous differences in grain size composition and physical mechanical properties, reflecting big differences in sedimentary age. This study also compared the grain size compositions of Dazhan formation loess from different geomorphic area, and found that the loess grain size at south seashore plain of Laizhou Bay is much bigger than that at east seashore hills, reflecting some differences in deposition means. The former one was deposited mainly by means of ground surface jumping and wind sand blowing, and the latter was deposited mainly bu means of suspension transport in the air. Finally, we proposed that based on spatial distribution, lithology and micropaleontological characteristics of the Dazhan formation loess, the loess provenance is dry marine deposit soil of later period of Late Pleistocene at Bohai shelf paleo seabed, which belongs to aeolian deposits.

关 键 词：莱州湾 大站组 黄土分层 粒度组成 

分 类 号：P736[天文地球—海洋地质]