| 鲁庆伟,江胜国,片磊,付方建,王西玉,姜昕沛,李小玉.天津南部地区末次盛冰期以来下切河谷及沉积相序特征研究[J].矿产勘查,2023,14(7):1043-1050 |
| 天津南部地区末次盛冰期以来下切河谷及沉积相序特征研究 |
| Characteristics of incised valley and sedimentary facies sequence since the last glacial maximum in southern Tianjin |
| 投稿时间：2023-05-08 修订日期：2023-06-09 |
| DOI：10.20008/j.kckc.202307005 |
| 中文关键词: 天津 下切河谷 末次盛冰期 陆海相互作用 沉积层序 |
| 英文关键词: Tianjin incised valley Last Glacial Maximum land-ocean interaction sedimentary sequence |
| 基金项目:本文受中国地质调查局项目“天津静海幅、唐官屯幅1∶5万区域地质调查”（津［2016］01040-14）和天津市规划和自然资源局项目“天津市蔡公庄乡幅、南台幅、中旺镇幅和太平镇幅1∶5万区域地质调查”（国土房任［2014］20号）联合资助。 |
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| 中文摘要: |
| 中国河口三角洲地区发育末次盛冰期（LGM=Last Glacial Maximum）下切河谷，为研究天津南部海陆交互作用平原区LGM下切河谷，本文通过钻孔、陡坎剖面调查、遥感解译和高密度电法剖面测量等工作手段，结合AMS14C测年、微体化石（有孔虫和介形类）和孢粉鉴定等测试进行综合研究，研究结果表明该区LGM以来发育3种沉积相序类型：类型Ⅰ（FS-Ⅰ）：由下切河道相—湖相—滨海相—海陆交互相（滨海湖沼/潟湖相）—河漫滩相构成；类型Ⅱ（FS-Ⅱ）：由下切河道相—湖相—滨海相—河道相—河漫滩相构成；成为下切河谷内不同时期河流序列的叠置；类型Ⅲ（FS-Ⅲ）：由LGM硬黏土—湖相—滨海相—海陆交互相（滨海湖沼/潟湖相）—河漫滩相构成。LGM时期古植被以云杉、松、蒿、藜等干冷植物为主，气候干冷；古河道空间格局和古流向受控于基底构造；汊道古河流发育且摆幅较大。与长江三角洲地区对比，该区下切河谷深度（宽约几百米、深20～30 m）及规模远不及前者（宽数十千米、深40～90 m）且不发育强潮河口湾相，原因在于没有开放海和统一的大河口。冰后期海平面上升，古微地貌低洼处受到海侵或地下水位上升湖相或湖沼发育形成全新世海侵基底泥炭，最大海泛面之后，不同微地貌处先后随着河流进积增强成陆，末次盛冰期以来沉积相序地层受控于全球海面变化和区域构造的影响，河海进退和河流摆动是沉积层序形成的直接原因。因研究区缺乏末次盛冰期以来下切河谷及沉积相序特征研究，故本文研究可为该区域末次盛冰期以来地层结构厘定、古环境恢复与演化以及水工环勘察、地下空间资源规划和开发利用等方面提供重要基础资料。 |
| 英文摘要: |
| The estuarine delta region of China developed incised valleys in the last glacial maximum （LGM）. Based on the borehole core， profile survey， remote sensing interpretation， high-density electrical profile measurement combined with AMS14C dating， analysis of microfossil （foraminifera and Ostracoda） and pollen， in this paper， the incised valley since the LGM in the sea-land interaction plain area of the southern Tianjin is studied comprehensively. Results show that there were three types of sedimentary facies sequence since LGM in this area： Type I （FS- I）： incised channel facies-lake facies-littoral-neritic facies-marine-land facies （The coast lacustrine facies / lagoonal facies）-concave flood plain facies； Type Ⅱ （FS-Ⅱ）： fluvial-lacustrine-littoral-neritic-fluvial-concave flood plain facies， and it is the superimposition of fluvial sequences of different periods in incised valley； Type Ⅲ （FS-Ⅲ）： LGM stiff clay-lacustrine-littoral-marine-land facies （Binhai lacustrine/lagoonal facies）- concave flood plain facies. In LGM period， picea， pinus， artemisia and chenopodium were the main palaeovegetation， the climate was dry and cold， the spatial pattern and palaeoflow direction of palaeochannel were controlled by basement structure， and the Palaeoriver of braided channel was developed and fluctuated greatly. Compared with the Changjiang Delta， the depth and scale of the incised valley （hundreds of meters in width and 20-30 meters in depth） are far less than the former （tens of kilometers in width and 40-90 meters in depth）， and there is no strong tidal estuary facies. The reason is that there is no open sea and a unified estuary. During the post-glacial period， the sea-level rose， the low-lying areas of paleomicro-topography were subjected to transgression or the ground water level rose， and the lacustrine facies or lacustrine marsh developed into transgressive basement peat of the Holocene. After the maximum sea level， the different areas of paleomicro-topography had been gradually enhanced into land with river accumulation. since the last glacial maximum， the sedimentary facies sequence stratigraphy was controlled by the change of global sea level and the influence of regional structure， the main cause of sedimentary sequence formation is that river swayed， river-sea advance and retreat. Due to the lack of research on the characteristics of incised river valleys and sedimentary facies sequences since the Last Glacial Maximum in the study area， the study can provide important basic data for the determination of stratigraphic structure， restoration and evolution of ancient environment， as well as hydrogeological and environmental exploration， underground space resource planning and development utilization in the area. |
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