苏北老黄河三角洲北部末次冰盛期以来沉积序列研究

ZK14孔是位于苏北老黄河三角洲北部地区的1个50m全取心钻孔,对其上部(1.0~22.0m)岩心沉积物的沉积特征分析,结合AMS14 C测年结果,表明末次冰盛期以来该地区主要沉积了硬黏土层和河流沉积(末次冰盛期至全新世早期,22.00~16.63m)、潮坪—浅海—老黄河三角洲沉积(全新世早期至公元1855年,16.63~1.00m),沉积物主要以黏土质粉砂和粉砂为主,夹少量细砂薄层。沉积物粒度频率曲线在16.63m以上为单峰-双峰分布交替出现,而在16.63m以下则出现三峰分布,向下过渡为双峰和单峰分布。沉积物粒度参数(分选系数、偏态和峰度)变化频繁,表明了物源(河流和海域来源)和沉积动力环境(径流、潮汐及波浪作用)的复杂性。ZK14孔末次冰盛期以来沉积序列的形成,受到海平面与物源变化以及沉积动力条件的共同影响。     

南海北部陆丰凹陷LF14井中新世古水深变化及沉降特征

南海北部陆丰凹陷内LF14井记录了早中新世至早上新世的海相沉积地层。古水深重建结果显示研究井位在早中新世突然发生海侵,水深迅速上升至最大值275m,随后经数次波动,整体处于中—外陆架环境,共记录了5个完整的海侵—海退层序。回剥分析方法重建的LF14井沉降史揭示了研究井位在中中新世(17.5—10Ma)处于快速沉降期,快速沉降导致的凹陷内沉积物的可容纳空间发育速率高和陆源物质供给充足是造成该阶段沉积速率高的两个重要因素;晚中新世—早上新世(10—4.53Ma)处于弱沉降期,推测东沙运动导致凹陷内的沉积物可容纳空间发育速率变小和陆源物质供给减少,造成该时期内研究井位沉积速率低。最后,依据定量重建的古水深变化在研究层段识别出一系列短暂存在的构造上升事件。     

南海北部陆丰凹陷LF14井中新世古水深变化及沉降特征*

南海北部陆丰凹陷内LF14井记录了早中新世至早上新世的海相沉积地层。古水深重建结果显示研究井位在早中新世突然发生海侵, 水深迅速上升至最大值275m, 随后经数次波动, 整体处于中—外陆架环境, 共记录了5个完整的海侵—海退层序。回剥分析方法重建的LF14井沉降史揭示了研究井位在中中新世(17.5—10Ma)处于快速沉降期, 快速沉降导致的凹陷内沉积物的可容纳空间发育速率高和陆源物质供给充足是造成该阶段沉积速率高的两个重要因素; 晚中新世—早上新世(10—4.53Ma)处于弱沉降期, 推测东沙运动导致凹陷内的沉积物可容纳空间发育速率变小和陆源物质供给减少, 造成该时期内研究井位沉积速率低。最后, 依据定量重建的古水深变化在研究层段识别出一系列短暂存在的构造上升事件。     

南海北部陆丰凹陷中新世底栖有孔虫组合与古环境演化研究

The Miocene epoch marks the most crucial period during the Cenozoic cooling trend, characterized by the Middle Miocene Climatic Optimum(MMCO) and a series of short–lived cooling events(Miocene isotope events).To understand the paleoenvironmental evolution along the shallow water shelf in the South China Sea during the Miocene, the benthic foraminiferal assemblage and total organic carbon content(TOC) were analyzed at Hole LF14 located in the Lufeng Sag, northern South China Sea. Three benthic foraminiferal assemblages(e.g., the Uvigerina spp. assemblage, the Cibicides spp. assemblage, and the Cibicidoides spp. assemblage), corresponding to different watermass conditions, were recognized based on Q–mode factor analysis. Early studies suggested that Hole LF14 was deposited under semienclosed bay, middle to outer shelf or even upper bathyal environment during ～18.7–4.53 Ma. The dominant Uvigerina spp. assemblage was characterized by low diversity and shallow infaunal to infaunal species, indicating a warm, low–oxygenation and eutrophic conditions since the Early Miocene to MMCO(～18.7–14.24 Ma). An abrupt sea level drop and significant faunal changes were recorded during 14.24–13.41 Ma, suggesting development of the East Antarctic Ice Sheets, which resulted in a drop of sea level and change in benthic foraminiferal assemblages along the shallow water shelf. Beyond the Uvigerina spp.assemblage, the Cibicides spp. assemblage became important during the middle–late Middle Miocene(14.24–11.54 Ma). This assemblage was dominated by epifaunal species with relative high diversity, suggesting high–energy, high–oxygenation and oligotrophic conditions with episodic supply of organic food. The dominant Cibicidoides spp. assemblage with high diversity, indicates a mesotrophic conditions with relative high–oxygen content during the Late Miocene to Pliocene(11.54–4.53 Ma). The appearance and continuous occurrence of Ammonia spp. and Pseudorotalia spp. since 10.02 Ma, may reflect the influence of the Kuroshio Current.     

秦皇岛海域海月水母碟状体分布与环境因子关系的多粒度分析

针对秦皇岛海域水母灾害频发问题,采用数据挖掘技术定量分析水母分布与环境因子之间的潜在关系,对水母灾害监测预警具有重要意义.本研究以2020年4月秦皇岛海域海月水母碟状体和海洋环境因子(温度、盐度、溶解氧和pH)数据作为研究对象,采用ID 3决策树作为分析模型,对海洋表层、底层环境因子分别进行多种粒度的数据离散化处理下,通过构建决策树挖掘海月水母碟状体密度分布特征与环境因子之间的定量关系;并采用K-折交叉验证、查准率、召回率与F1分数指标,以及相关性进行实验验证与分析.结果 表明:对于海月水母碟状体的密度分布,预测效果最佳的是基于平均值和标准差离散化的海洋表层环境因子构建的决策树;相关性由高到低依次为:盐度、溶解氧、pH和温度.当SSS ∈[31.49,31.79)、SSDO∈ [9.18 mg/L,9.50 mg/L)、SSpH∈ [8.12,8.21)和SST∈ [11.29℃,11.71 ℃)时,海月水母碟状体密度预测结果为高.本文研究成果可加深对该海域海月水母生存环境的了解,为进一步研究该海域大型水母灾害的监测预警提供技术支撑.