晚更新世以来台湾浅滩西北近岸沉积特征与古环境演化

对取自台湾浅滩西北部福建东山岛外的浅钻ZK2孔进行了包括AMS14C测年、粒度、微体古生物、碎屑矿物和黏土矿物等分析。结果表明该孔地层中存在两个明显的海相层和其间的两个陆相层,顶部的海相层为全新世高海平面以来形成的被现代潮流作用改造的现代沉积和残留沉积混合体;底部陆相层为MIS4期低海平面时期形成的河流沉积;中间的细粒沉积层又可划分为下部形成于MIS3期的以潟湖、潮坪和盐沼交替出现的海相沉积层,以及上部形成于MIS3期末到盛冰期出露水面之前的陆上沟谷充填沉积;台湾海峡南部在MIS3期之后发生了明显的构造沉降过程,但是在末次盛冰期海峡南部仍然出露水面之上形成了沉积间断面。本文研究内容为今后在台湾浅滩西北边缘到福建东南近岸区深入开展沉积学、地层学及古环境演化研究提供了新的参考。     

阿塔卡马海沟表层水颗粒有机碳与微生物群落呼吸作用的时空变化研究

海沟是全球大洋体系的重要组成部分。研究这一极端环境的生物地球化学循环过程有助于我们进一步理解海洋的物质循环。前期研究发现,海沟表层水体的初级生产力(NPP)对海沟沉积物埋藏的有机碳性质具有重要影响,但是,颗粒有机碳(POC)在沉降过程中被微生物呼吸和降解的过程尚不清楚。因此,本研究利用2018年春"太阳号"阿塔卡马海沟(Atacama Trench)国际联合航次SO261所采集的表层水样品,测试其中POC浓度、C/N、δ¹³C、δ¹⁵N等参数,并结合0.2—0.8、0.8—3.0、>3.0μm三种粒径微生物群落呼吸(microbial community respiration,MCR)速率测试,探究其日变化模式及不同站位的空间变化模式,进而衡量微生物对POC的呼吸降解作用。结果表明,该海域表层水中对POC降解占主导作用的微生物类群粒径为0.8—3.0μm;24 h时间序列实验表明MCR随时间呈现"M"型曲线的双峰变化模式,且和C/N、δ¹³C、δ¹⁵N等参数变化趋势吻合,表明同一站位的呼吸速...     

海洋生态文明视域下河口沙坝-潟湖生态修复思路探究

加大海岸整治修复力度是推进海洋生态文明建设的必然要求。沙坝-潟湖海岸具有典型的生态系统和独特的社会价值,同时也因人类活动受到不同程度破坏,是“蓝色海湾”等整治修复项目的重要对象。文章以辽宁省浮渡河口沙坝-潟湖为例,总结国内外河口沙坝-潟湖主要生态修复思路和方法,提出生态修复过程中沙坝-潟湖受损机制和生态修复评估体系构建两个关键技术问题。在此基础上,为深入推进我国海岸生态保护修复管理和海岸整治修复工程实践,需要做好顶层设计和提升整治修复能力两方面主要工作。     

卫星导航定位中DOP的精度增强作用分析

通过理论推导分析了 DOP 的一些性质,并进行了算例分析。 实验结果表明,在一些特殊应用环境中, DOP 值会随着星地空间几何布局的改善而大幅减小,以至于小于 1,从而增强了用户位置和时间偏差参数的精度; 结果还表明,导航解算方程的权逆阵的条件数在星地空间几何布局改善的条件下具有与 DOP 极为相似的变化规律,并且可以反映用户等效测距误差对于导航解相对误差的敏感性,亦可作为精度评估的一种度量方法。     

南海北部陆坡深水区沉积物输送模式探讨

南海北部陆坡深水区沉积物输送模式复杂多样,研究发现主要有碎屑流、浊流、砂质碎屑流、碳酸盐岩重力流、块体搬运、河流搬运、深水水道搬运7种类型,它们共同影响着南海北部陆坡沉积物类型和储层分布。其中(砂质)碎屑流沉积、块体搬运沉积、河流供给、深水水道砂是南海北部深水储层的主要成因,而纯粹的浊积岩在该地区发育不广泛。珠江口盆地的深水储层受到河流的供给和后期流体改造的影响,并且存在碳酸盐岩重力流沉积物薄层,证明该地区水动力条件较强;琼东南盆地深水储层分布受到了碎屑流控制和深水水道的影响,相对浅水区来看可能存在分选较好、干净的砂体储层,具有良好的勘探潜力。     

单向流作用下沉底物体对水流结构和地形变化的影响

A one-phase model is established by using CFD(Computational Fluid Dynamics) software,which includes a hydrodynamic sub-model,an erosion-deposition and a moving boundary method.in the model,the velocity field surrounding obstacles on the seabed is computed by a three dimensional k-εturbulence closure sub-model.Erosion and deposition caused by the transportation of suspended load and bed load are also calculated.The evolution of bedform is simulated in a mobile grid technipue.The three-dimensional flow pattems and evolution of bedform around three different obstacles are simulated using the one-phase model.The hydrodynamic process and sediment transportation process surrounding the obstacles are reproduced in detail. The simuated results of bedform evolution are in good agreement with laboratory measurement results in 2005.     

Improved understanding of petroleum migration history in the Hongche fault zone,northwestern Junggar Basin (northwest China): Constrained by vein-calcite fluid inclusions and trace elements

Calcite veins and cements occur widely in Carboniferous and Permian reservoirs of the Hongche fault zone, northwestern Junggar Basin in northwest China. The calcites were investigated by fluid inclusion and trace-element analyses, providing an improved understanding of the petroleum migration history. It is indicated that the Hongche fault behaved as a migration pathway before the Early Cretaceous, allowing two oil charges to migrate into the hanging-wall, fault-core and footwall reservoirs across the fault. Since the Late Cretaceous, the Hongche fault has been sealed. As a consequence, meteoric water flowed down only into the hanging-wall and fault-core reservoirs. The meteoric-water incursion is likely an important cause for degradation of reservoir oils. In contrast, the footwall reservoirs received gas charge (the third hydrocarbon event) following the Late Cretaceous. This helps explain the distribution of petroleum across the fault. This study provides an example of how a fault may evolve as pathway and seal over time, and how reservoir diagenetic minerals can provide clues to complex petroleum migration histories.     

南海北部磁场特征及其构造意义

根据南海北部的地磁场数据及其化极异常特征,该区由北向南可分为复杂异常区、高磁异常区、陆坡磁异常平静区(磁静区)和海盆磁条带区四大构造特征区.其中,磁静区可为内磁静区1、内磁静区2和外磁静区三部分.该区磁性基底反演结果表明,外磁静区磁性基底深度为6-7km,介于内磁静区(8-10km)和海盆区(4-5km)之间,可能是前新生代残留古洋壳.外磁静区和下地壳高速层相对应,指示其可能是在裂前或裂间由底侵作用形成的.陆架坡折带附近的F2断裂是内磁静区的北侧边界,指示了南海北部陆壳向过渡壳的转变分界;位于下陆坡与海盆的交界处的F4断裂为外磁静区的南侧边界,F3断裂可能指示了洋陆分界线的位置.     

Bathymetry enhancement by altimetry-derived gravity anomalies in the East Sea (Sea of Japan)

The gravity-geologic method (GGM) was used to enhance the bathymetry of the East Sea (Sea of Japan) with satellite altimetry-derived free-air gravity anomalies and shipborne depth measurements. By comparison with the bathymetry model of Smith and Sandwell’s (SAS) approach (1994), GGM was found to have an advantage with short wavelength (≤12 km) components, while SAS better predicts longer wavelength (≥25 km) components, despite its dependency on density contrast. To mitigate this limitation, a tuning density contrast of 10.25 g/cm³ between seawater and the seafloor was primarily estimated by the downward continuation method and then validated by the check points method with GGM. Similarly, SAS is limited by the “A” value in low-pass part of the Wiener filter, which defines the effective range of the wavelength components on bathymetry. As a final result, we present an enhanced GGM bathymetry model by integrating all available data.     

莱州湾沉积物粒度与重金属分布特征

作者依据2019年8月份莱州湾海洋沉积物调查资料,分析了该海域表层沉积物粒径组成、重金属时空分布特征并评价了其生态风险。结果显示,莱州湾沉积物分为砂质粉砂、粉砂、粉砂质砂和砂4种类型,以砂质粉砂为主,其次为粉砂与粉砂质砂,再次为砂,中值粒径平均58.956μm;表层沉积物中Cr、Zn、Pb、Cu、As、Cd、Hg和TOC平均含量分别为57.6、52.6、18.7、15.3、9.14、0.130、0.0234 mg/kg和0.222%;由于河流排海物质和莱州湾内潮流运动,导致Cu、Pb、Zn、As、Cr和Cd基本呈现中部海域含量较高,西部海域高于东部海域的特征,东南部海域Cd、Hg与矿产资源的开发相关;14.3%的站位综合潜在生态风险属于中生态风险,Cd对综合潜在生态风险指数的贡献率最高,为主要潜在生态风险因子;研究区域中重金属Cu、Zn含量的分布与沉积物粒径和有机碳的含量密切相关。