大兴安岭东麓白土山组地层的沉积学特征——对地层划分的指示  

Sedimentological Characteristics of the Baitushan Formation in the Eastern Foothills of the Great Xing'an Range:Implications for stratigraphic divisions

作　　者：侯心茹 谢远云[1,2] 康春国[3] 迟云平[1,2] 吴鹏 孙磊 孙杨 孙建华 HOU XinRu;XIE YuanYun;KANG ChunGuo;CHI YunPing;WU Peng;SUN Lei;SUN Yang;SUN JianHua(School of Geographical Sciences,Harbin Normal University,Harbin 150025,China;Heilongjiang Key Laboratory of Geographical Environment Monitoring and Spatial Information Service in Cold Regions,Harbin Normal University,Harbin 150025,China;Department of Geography,Harbin University,Harbin 150086,China)

机构地区：[1]哈尔滨师范大学地理科学学院,哈尔滨150025 [2]哈尔滨师范大学寒区地理环境监测与空间信息服务黑龙江省重点实验室,哈尔滨150025 [3]哈尔滨学院地理系,哈尔滨150086

出　　处：《沉积学报》2023年第3期720-734,共15页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(42171006,41871013);黑龙江省自然科学基金项目(LH2020D009)。

摘　　要：白土山组是松嫩平原下更新统的底界地层,深入分析其地层属性特征,对于第四纪地层划分有重要意义。然而该地层薄弱的研究基础限制了松嫩平原地层划分及区域构造—地貌—水系演化等问题的深层理解。选择腰白土、平安镇、绰尔河和王府屯剖面为研究对象,对其沉积学和重矿物属性进行分析。结果显示,腰白土和平安镇剖面是经典白土山组,岩性主要为灰白色砂砾石夹黏土—细颗粒碎屑透镜体,透镜体中见斜层理(向东南倾伏),砾石分选差,呈次棱角—次圆,弱风化;王府屯剖面出现向西北倾伏的大型板状交错层理,砾石成分以石英质占绝对优势(87.5%)。各剖面皆不含辉石和角闪石等造岩矿物,其中,腰白土和平安镇重矿物组成高度相似,绰尔河以磷灰石—榍石—石榴子石作为诊断性矿物;而王府屯有蓝晶石、十字石和透闪石等变质矿物及独居石存在,不含绿帘石,极稳定矿物显著富集。基于此,前三者砾石母岩为中酸性岩浆岩,沉积物来源于大兴安岭,为冲—洪积作用下流水搬运的产物;王府屯剖面为河流阶地成因,沉积物来自松嫩平原东南山地。因此,平安镇剖面为腰白土模式的经典白土山组剖面,绰尔河剖面是否为白土山组尚待进一步年代学研究,而王府屯剖面不能视为白土山组。The Baitushan Formation is the lowest stratum of the Early Pleistocene in the Songnen Plain.In-depth analysis of its stratigraphic attributes is highly significant for Quaternary stratigraphic division.However,the lack of other studies of the Baitushan Formation limit the deep understanding of relevant problems,such as stratigraphic division of the Songnen Plain and the evolution of regional tectonism,geomorphological factors and drainage.Therefore,the Yaobaitu,Ping'anzhen,Chuo'erhe and Wangfutun profiles were selected for analysis of their sedimentological and heavy mineral properties.It was found that the Yaobaitu and the Ping'anzhen profiles are the standard Baitushan Formation strata,with lithology consisting mainly of grayish-white sand and gravels interspersed with clay and finegrained clastic lenses,with oblique bedding(dipping to the southeast) seen in the lenses,poorly sorted,subangular to sub-rounded and weakly weathered gravels.By contrast,the Wangfutun profile shows evidence of a large cross-bedded plate tilting to the northwest,with gravel composition almost completely dominated by quartz(87.5%).There are no main rock-forming minerals(e.g.,pyroxene,hornblende) in any of the profiles.The heavy mineral composition of the Yaobaitu and the Ping'anzhen profiles are highly similar,but apatite-sphene-garnet are the diagnostic minerals in the Chuo'erhe profile.Metamorphic minerals(e.g.,kyanite crosstalk,tremolite and monazite) are contained only in the Wangfutun profile.This profile does not contain epidote,and extremely stable minerals are greatly enriched.Based on this,the lithology of the gravel parent rocks of the Yaobaitu,Ping'anzhen and Chuo'erhe profiles are intermediate-acid magmatic rocks.The sediments come from the Great Xing'an Range as the products of running water transport in an alluvial-proluvial process.The Wangfutun profile indicates a river terrace origin;its sediments are derived from the southeastern mountainous area of the Songnen Plain.In summary,the Ping'anzhen and the Yaobaitu profile

关 键 词：白土山组 松嫩平原 重矿物 沉积环境 地层划分 

分 类 号：P531[天文地球—古生物学与地层学]