南黄海西部日照海域海侵沉积地层及其古环境意义  

Transgressive Succession Offshore Rizhao in Western South Yellow Sea and Paleo⁃environmental Implications

作　　者：秦亚超[1,2] 孙荣涛 王红[1,2] 田振兴[1,2] 徐扬 温珍河[1,2] QIN YaChao;SUN RongTao;WANG Hong;TIAN ZhenXing;XU Yang;WEN ZhenHe(Key Laboratory of Gas Hydrate,Ministry of Natural Resources,Qingdao Institute of Marine Geology,Qingdao,Shandong 266071,China;Laboratory for Marine Mineral Resources,Qingdao National Laboratory for Marine Science and Technology,Qingdao,Shandong 266071,China;School of Resource and Environmental Engineering,Shandong University of Technology,Zibo,Shandong 255049,China)

机构地区：[1]自然资源部天然气水合物重点实验室,青岛海洋地质研究所,山东青岛266071 [2]海洋国家实验室海洋矿产资源评价与探测技术功能实验室,山东青岛266071 [3]山东理工大学资源与环境工程学院,山东淄博255049

出　　处：《沉积学报》2020年第4期790-809,共20页Acta Sedimentologica Sinica

基　　金：中国地质调查局项目(GZH201400206,DD20160139,DD20190236,DD20190377);中国—东盟海上合作基金项(12120100500017001);国家自然科学基金项目(41706069)。

摘　　要：南黄海西部日照海域晚更新世海侵沉积地层广泛出露。基于本区18个站位柱状岩芯的剖面观察、有孔虫和介形虫鉴定、粒度分析、腹足类纹沼螺(Parafossarulus striatulus(Benson))和钙质结核的AMS 14C年龄识别了沉积相,并探讨了MIS 3阶段的沉积历史和古环境特征,同时大致估算出末次海侵过程中水下平原的剥蚀厚度。结果表明,在日照外海、废黄河水下三角洲以北,表层覆盖着全新世早期海侵过程中所形成的砂质改造层,灰色,席状,无层理,厚度薄,通常在10~40 cm左右。海侵沙席之下为海陆过渡相沉积,可细分为滨岸潟湖相、沙坝相和滨海相等。底栖有孔虫组合几乎都以Ammonia beccarii(Linné)vars.为优势种,其他常见种为Elphidium magellanicum Heron⁃Allen et Earland、Cribrononion subincertum(Asano)、Textularia foliacea Heron⁃Allen&Earland、Elphidium advenum(Cushman)、Protelphidium tuberculatum(d'Orbigny)、Cavarotalia annectens(Parker et Jones)和Pararotalia nipponica(Asano)等,指示滨岸浅水沉积环境。地层沉积年代为MIS 3阶段的中期或中早期,当时的海平面波动区间主要位于现今海平面以下20 m至31 m之间。这套地层为海进沉积,是海平面波动过程中所形成的沉积旋回,沉积过程中曾经历过反复的暴露和氧化,从下向上,其垂向层序可分为两个序列:(1)滨岸潟湖—沙坝沉积或仅见沙坝沉积,为砂质沉积,分布在海侵沉积区的北部和西部;(2)滨岸潟湖—滨海相沉积,为粉砂质沉积,分布在海侵沉积区的东南部。前者沿着古海岸线分布,后者距离古海岸线较远。表层钙质结核的大量富集,可能意味着末次海侵的强度已经剥露至土壤剖面下部的钙积层。据此估计,在末次海侵过程中,本区水下平原的平均剥蚀厚度约为50~70 cm。Transgressive succession is widely exposed offshore Rizhao in the western South Yellow Sea.The deposi⁃tional facies of 18 sediment cores from these strata were identified and the sedimentary history and paleo⁃environmen⁃tal features were recognized from profile observations,foraminifera and ostracoda identification,grain⁃size analysis,and AMS 14C dating of freshwater snails(Parafossarulus striatulus(Benson))and nodular calcretes.The approximate denudation depth during the last transgression was also estimated.It was found that the surface layer of the transgres⁃sive deposit area is covered by gray reworked sands without bedding to a thickness of 10⁃40 cm as a result of erosion and reworking by marine dynamics during the last transgression.The underlying strata are composed of land⁃sea tran⁃sition facies,including lagoon facies,sand bar facies and littoral facies.Ammonia beccarii(Linné)vars.prevails throughout the foraminiferal assemblages in association with Elphidium magellanicum(Polystomella)Heron⁃Allen&Earland,Cribrononion subincertum(Asano),Textularia foliacea Heron⁃Allen&Earland,Elphidium advenum(Cushman),Protelphidium tuberculatum(d’Orbigny),Cavarotalia annectens(Parker&Jones),and Pararotalia nipponica(Asano),indicating a coastal shallow⁃water environment.These strata were deposited in the early⁃to⁃mid or mid⁃MIS 3,when the paleo⁃sea⁃levels fluctuated mainly between 20 and 31 m below the present sea level.This suite of strata were identified as a transgressive succession that formed during a period of frequent sea⁃level fluctua⁃tions and experienced long⁃term repeated exposure and oxidization.It is classified upwards into two categories:(1)sandy lagoon⁃sand bar deposits,or sand bar deposits only,in the north and west of the transgressive deposit area along the paleo⁃coastline;and(2)silty lagoon⁃littoral deposits in the southeast of the transgressive deposit area and distant from the paleo⁃coastline.Pronounced enrichment of pedogenic calcretes possibly indicat

关 键 词：柱状沉积物 有孔虫 介形虫 粒度 钙质结核 海侵沉积地层 南黄海 

分 类 号：P736.21[天文地球—海洋地质]