南海北部沉积盆地油田水水化学特征及其成因分析

油田水是沉积盆地中的重要流体,研究其水文地球化学特征对油气生成、富集等有重要指示意义。为进一步研究南海珠江口盆地珠三拗陷和北部湾盆地涠西南凹陷油田水的特征和成因,分别在珠三坳陷的珠江组和珠海组采集油田水样5个,在涠西南凹陷的涠洲组采集油田水样4个,对研究区油田水进行了常规阴阳离子含量、D和18O同位素组成分析。结果显示:珠江口和北部湾盆地油田水溶解性总固体总体较高,均为Cl—Na型水,油田水各特征离子间关系(钠氯系数、氯镁系数、钙镁系数)和氢氧同位素关系共同显示两处油田水均起源于海水并储存于封闭性较好的地层中,在埋藏过程中可能还经历了较小程度的蒸发和降水补给,并推测其形成受薄膜渗滤作用影响。     

湿地沉积物-水界面营养盐交换的定量估算

为有效控制湖泊内源营养盐的释放,探讨了不同物理改良措施(覆沙、底质疏松)对沉积物-水界面营养盐的释放通量控制效果。利用原位孔隙水采样技术(Peeper)来获得沉积物孔隙水剖面,对改良后湿地沉积物孔隙水营养盐的垂向分布及其扩散通量进行了研究。结果发现,改良后沉积含水率、孔隙率分别提高了91%和54%。水土界面附近,随剖面深度增加,孔隙水中PO₄3-、NH₄+、NO₃-及NO₂-浓度分布符合指数关系,PO₄3-、NH₄+在8 cm左右达到最大值。种植芦苇后沉积物孔隙水中PO₄3-、NH₄+均有不同程度的下降,改良措施能有效降低表层弱结合态磷在总磷中比例但增加铁磷的比例,种植芦苇可强化这一效应。运用Fick第一定律对剖面孔隙水营养盐的扩散通量进行估算,发现沉积物经疏松后,NH₄+、PO₄3-的扩散通量由57.47~72.19μg/(m2·d)和2.55~3.21μg/(m2·d)变为-95.54~-130.94μg/(m2·d)和1.50~2.05μg/(m2·d),可考虑疏松沉积物-水界面附近沉积物来作为控制湖泊内源污染的有效手段之一。     

重建与模拟中过去500年厄尔尼诺和东亚夏季风关系的年代际变化

在厄尔尼诺衰减年夏季,西北太平洋上通常会激发异常反气旋,并加强东亚夏季风。基于过去500年的重建数据,分析发现厄尔尼诺和东亚夏季风的关系并不稳定,而是存在年代际震荡。特别是在17世纪的小冰期,在厄尔尼诺衰减年的夏季,西北太平洋上空的环流表现为气旋异常。通过EOF分解发现,厄尔尼诺引起的东亚夏季风异常的年代际变化有两种主导模态：第一种是偶极子模态,表现为中南半岛和菲律宾群岛的负降水异常,以及中国东部降水增多;第二种是东亚地区表现为一致变化的均一模态。在厄尔尼诺衰减年的夏季,西北太平洋异常反气旋的年代际变化主要是由偶极子模态控制,且与有效太阳辐射呈正相关。在小冰期,太阳辐照度剧烈减少,从而导致衰减年的夏季西北太平洋出现气旋型异常。模式模拟可以重现重建资料得到的偶极子和均一模态,并且反气旋的年代际变化同样也是由偶极子模态引起的。从内部变率的视角来看,偶极子模态与类厄尔尼诺型的太平洋气候平均态有关。当关注于外部强迫的响应,尽管模式集合平均与有效太阳辐射表现为负相关,但是集合成员之间并不是完全一致的年代际变化,存在较大的方差。说明对于外强迫的响应,模式与重建资料仍存在一定的差异。

     

从水/岩交换作用判定福建锦屏金银矿的成因

锦屏金银矿位于锦屏小坑成矿带的北段,产于中元古界龙北溪组变质基底构造天窗东侧的上侏罗统南园组火山岩中。矿液具低18O特征,水/岩值较大,表明成矿介质水为大气降水,属被加热的大气降水热液矿床。     

长江流域水储量变化的时间变化特征及归因分析

为开展长江流域水储量变化（Terrestrial Water Storage Change,T_WSC）的时间变化特征及归因分析研究,结合GRACE（Gravity Recovery and Climate Experiment）卫星观测及水文模拟,重建并分析了长江流域1988—2012年逐月T_WSC;基于13个实验情景的模拟结果,定量区分了气候波动及关键人类活动（土地利用变化、水库调蓄）对T_WSC的相对贡献。结果表明:①流域平均T_WSC、降水、蒸散发、径流深分别以0.1 mm/a、-3.5 mm/a、0.6 mm/a、-4.2 mm/a的线性速率增减;②逐月非季节性T_WSC与南方涛动指数（Southern Oscillation Index,I_SO）呈现显著负相关性（α < 0.01）;③气候波动对T_WSC影响占主导地位,水库调蓄与气候波动对月平均T_WSC的相对贡献率存在负相关性;④三峡水库运行后,水库调蓄对月平均T_WSC的影响显著增强,且呈现季节性规律,即1—5月削减T_WSC,7—12月增加T_WSC。本研究提供了一种T_WSC归因分析研究框架,研究结果可为长江流域水资源规划管理提供决策支持。     

莺歌海盆地地层水的化学特征及其石油地质意义

4件水样取自南海写歌海盆地的东方1-1-1及东方1-1-2两口钻井中,两口井均位于该断陷盆地的中心,取样深度、层位及化学分析结果详见表1和表2。     

床面粗糙度和底床渗透率对泥-水界面物质交换特性的影响

泥-水界面物质交换过程对自然水体中污染物的迁移转化起重要作用,粗糙底床界面物质交换过程涉及到床面粗糙度和底床渗透率的影响。通过实验室环形水槽实验测量得到水力粗糙砂质底床条件下界面物质交换通量的定量数据和变化特征,采用参数化方法分析有效扩散系数与其主要影响参数之间的依赖关系。实验结果表明,在实验参数变化范围内,受上覆水平均流速、床面粗糙度和底床渗透率的共同作用,有效扩散系数从水力光滑区、过渡粗糙区至完全粗糙区呈现较为明显的分段变化特征,采用渗透率雷诺数可将有效扩散系数与其主要影响参数的依赖关系进行较为一致的描述。基于双参数(粗糙雷诺数和渗透率雷诺数)分析,确定了不同流动区域的相应阈值以合理表征床面粗糙度和底床渗透率对界面物质交换特性的综合影响。     

床面粗糙度和底床渗透率对泥-水界面物质交换特性的影响

泥-水界面物质交换过程对自然水体中污染物的迁移转化起重要作用,粗糙底床界面物质交换过程涉及到床面粗糙度和底床渗透率的影响。通过实验室环形水槽实验测量得到水力粗糙砂质底床条件下界面物质交换通量的定量数据和变化特征,采用参数化方法分析有效扩散系数与其主要影响参数之间的依赖关系。实验结果表明,在实验参数变化范围内,受上覆水平均流速、床面粗糙度和底床渗透率的共同作用,有效扩散系数从水力光滑区、过渡粗糙区至完全粗糙区呈现较为明显的分段变化特征,采用渗透率雷诺数可将有效扩散系数与其主要影响参数的依赖关系进行较为一致的描述。基于双参数(粗糙雷诺数和渗透率雷诺数)分析,确定了不同流动区域的相应阈值以合理表征床面粗糙度和底床渗透率对界面物质交换特性的综合影响。     

西江流域水文水化学因子对岩溶系统碳汇通量的影响分析

河流岩溶碳汇通量的研究对于掌握全球碳循环机制、寻找"遗漏碳汇"具有重要意义。水文地质特征是岩溶动力系统的重要单元,为了分析河流岩溶碳汇在通量、长时间尺度的变化,本文选取受湿润季风气候影响显著的西江梧州断面为研究对象,探讨了2011~2015年西江流域流量、水位、本地降水量、水温、pH值、电导率、Ca~(2+)和HCO_3~-浓度等水文水化学因子对岩溶碳汇通量的影响。结果表明:1岩溶碳汇通量与流量、水位的相关系数均在0.95以上,岩溶碳汇通量与流量达到了同步变化,岩溶碳汇通量与水位良好的相关关系则是通过水位对流量响应表现出来;降水通过不同方式进入河流直接改变地表径流状况,进而影响岩溶碳汇通量。2水温对岩溶碳汇通量的影响与西江流域雨季与夏季在同一时间段的气候特点有关,属于次要因子。3监测点水体常年呈弱碱性,pH值对岩溶碳汇通量的影响较弱;电导率、Ca~(2+)和HCO_3~-浓度主要受流量影响,对岩溶碳汇通量变化的影响甚微。由此推断,流量是岩溶碳汇通量的主控因素。     

冷水柳珊瑚骨骼化石重建的早全新世南海中层水十年际变化

冷水珊瑚可以提供其生长期内周围环境变化的信息, 有望填补中-深层海洋高分辨率重建材料的空缺。本文利用“深海勇士”号载人深潜器在甘泉海台西南角海山上(16.55°W, 110.89°E; 水深1119.3m)采集的柳珊瑚样品(SY185-9)开展探索性研究, 检验冷水珊瑚高分辨率古环境重建的应用价值。X射线衍射(XRD)分析结果表明SY185-9的矿物成分主要为镁方解石(Mg_0.06Ca_0.94CO₃); 骨骼横切面的¹⁴C测年结果显示SY185-9生长于早全新世, 时间跨度为9621±135~8922±114a B.P.; 利用环境扫描电子显微镜结合能谱仪和电子探针, 分析SY185-9骨骼横切面的元素组成和变化, 其中Mg/Ca比值指示了SY185-9生长时期平均海水温度为4.7±0.9℃, 较现代相同位置处的平均海水温度高约0.9℃, 可能反映早全新世南海中层水温度较现代略高的特征, 但也需注意冷水珊瑚Mg/Ca温度计算公式的区域适用性和珊瑚生命效应问题; Mg/Ca记录的频谱分析结果揭示显著的十年-百年际尺度波动, 可能反映中层水温度的自然变率, 或因局地海山地形而造成的中层海水与海表气候之间的密切联系。

     

Kinematics of Convergence and Deformation in Luzon Island and Adjacent Sea Areas:2-D Finite-Element Simulation

The Luzon Island is a volcanic arc sandwiched by the eastward subducting South China Sea and the northwestward subducting Philippine Sea plate.Through experiments of plane-stress,elastic,and 2-dimensional finite-element modeling,we evaluated the relationship between plate kinematics and present-day deformation of Luzon Island and adjacent sea areas.The concept of coupling rate was applied to define the boundary velocities along the subduction zones.The distribution of velocity fields calculated in our models was compared with the velocity field revealed by recent geodetic (GPS) observations.The best model was obtained that accounts for the observed velocity field within the limits of acceptable mechanical parameters and reasonable boundary conditions.Sensitivity of the selection of parameters and boundary conditions were evaluated.The model is sensitive to the direction of convergence between the South China Sea and the Philippine Sea plates,and to different coupling rates in the Manila trench,Philippine trench and eastern Luzon trough.We suggest that a change of±15° of the di rection of motion of the Philippine Sea plate can induce important changes in the distribution of the computed displacement trajectories,and the movement of the Philippine Sea plate toward azimuth330° best explains the velocity pattern observed in Luzon Island.In addition,through sensitivity analysis we conclude that the coupling rate in the Manila trench is much smaller compared with the rates in the eastern Luzon trough and the Philippine trench.This indicates that a significant part of momentum of the Philippine Sea plate motion has been absorbed by the Manila trench;whereas,a part of the momentum has been transmitted into Luzon Island through the eastern Luzon trough and the Philippine trench.     

从东海石油地质重要进展看西太平洋大陆边缘新生代盆地的构造演化——一种海沟向洋后退的残余弧后盆地演化模式

东海盆地石油地质研究在近二十年里主要取得五方面的进展 :证明了盆地是由一组大陆边缘新生界由西向东逐个变新的“盆地群体”组成 ,建立了陆架地区以组为单位的整个新生代地层单元 ,详细划分了西湖凹陷的内部地质结构 ,认定了煤和煤系沉积是东海陆架区的主力油气源岩 ,通过大量钻井验证了盆地中三类不同成因的圈闭。从环西太平洋盆地形成的地球动力学背景看 ,西太平洋是一个自北而南的沟—弧—盆 (陆缘海 )系统 ;大体以台湾海峡为界 ,东海盆地是一个由转换或被动边缘演化而来的聚敛边缘 ,而南海属于由活动或聚敛边缘转化而来的被动边缘。东海盆地与菲律宾海盆地具有相似的时空演化特征 ,由此论证了东海新生代盆地属于残余弧后向洋后退盆地     

南海及邻区新构造运动表现特征及其主控因素

南海具有复杂的地质构造背景,扩张结束以后,新构造运动活跃,但各区域新构造运动发生的时间及运动特征有较大差异。本文综合分析了南海各区域构造演化事件、现今构造格局及新构造运动的基本特征,认为南海新构造运动的起始时间为中中新世（约15 Ma）较合理。在此基础上,收集和整理了南海及邻区最新的地质和地球物理资料,对南海海域新构造期地层差异升降、活动断裂、天然地震以及岩浆活动等新构造表现形式进行了综合分析,系统总结了南海新构造运动特征,并根据活动断裂、天然地震以及岩浆活动等特征和分布规律分析,认为南海海域新构造的表现形式之间存在较大的耦合性。本文根据新构造运动表现形式在空间分布的不平衡性,将南海及邻区划分为1个强构造活动区、3个中等强度构造活动区以及1个弱构造活动区,并结合研究区应力场特征分析,认为南海新构造运动主要受控于东部菲律宾海板块和太平洋板块对东亚大陆边缘的持续俯冲碰撞作用。     

Temporal and Spatial Characteristics of Mesoscale Eddies in the Northern South China Sea: Statistics Analysis Based on Altimeter Data

Mesoscale eddies are active and energetic in the South China Sea (SCS), and play an important role in regulating the multi-scale circulation and mass transportation in the region, especially for those long-lived strong eddies. Using AVISO altimeter data and outermost closed contour sea level anomaly method, this study identified and tracked mesoscale eddies in the northern SCS during 2011-2018, and focused on the temporal and spatial characteristics of mesoscale eddies in recent years. Similarly to previous results in this region, statistical results show that about 8.6 anticyclonic eddies and 4.5 cyclonic eddies (lifetime > 28 days) were born per year. Among them, about 1/3 of the total number are strong eddies (lifetime > 45 days), showing relatively strong dynamic characteristics, such as strong Eddy Kinetic Energy (EKE) and highly nonlinear feature. Statistics also show significant seasonal variability in mesoscale eddies’ birth places, trajectories and distribution of frequency of occurrence. Specifically, anticyclonic eddies mainly form at the north part of Luzon Strait between autumn and winter, and then move southwestward along isobaths. During this period, the largest value of the frequency of occurrence is over 30%. In summer, most of them form in the west off Luzon Island, and then move westward paralleling to latitude lines. In contrast, cyclonic mainly form in the west off Luzon Strait, and then move westward in winter and spring. During this period, the largest value is about 26%. In addition, observation finds that the strong mesoscale eddy pair could generate off the southwest of Taiwan Island. Analysis of the Kuroshio SCS Index (KSI) implies that loop current caused by Kuroshio intrusion is the most important mechanism for the formation of eddy pair.     

Temporal Geochemical Evolution of Neogene Magmatism in the Baguio Gold–Copper Mining District (Northern Luzon, Philippines)

Baguio, in the Central Cordillera of Northern Luzon, is a district that displays porphyry copper and epithermal gold mineralization, associated with Early Miocene–Pliocene–Quaternary calc‐alkaline and adakitic intrusions. Systematic sampling, K‐Ar dating, major and trace elements, and Sr, Nd, Pb isotopic analyses of fresh magmatic rocks indicate three magmatic pulses: an Early Miocene phase (21.2–18.7 Ma), a Middle–Late Miocene phase (15.3–8 Ma) and finally a Pliocene–Quaternary event (3–1 Ma). The first phase emplaced evolved calc‐alkaline magmas, essentially within the Agno Batholith complex, and is thought to be related to the westward‐dipping subduction of the West Philippine Basin. After a quiescence period during which the Kennon limestone was deposited, magmatic activity resumed at 15.3 Ma, in connection with the start of the subduction of the South China Sea along the Manila Trench. It emplaced first petrogenetically related and relatively unradiogenic low‐K calc‐alkaline lavas and intermediate adakites. Temporal geochemical patterns observed from 15.3 to 1 Ma include progressive enrichment in K and other large ion lithophile elements, increase in radiogenic Sr and Pb and corresponding decrease in radiogenic Nd. These features are thought to reflect the progressive addition to the Luzon arc mantle wedge of incompatible elements largely inherited from South China Sea sediments. The origin of the long quiescence period, from 8 to 3 Ma, remains problematic. It might represent a local consequence of the docking of the Zambales ophiolitic terrane to Northern Luzon. Then, magmatic activity resumed at 3 Ma, emplacing chemically diversified rocks ranging from low K to high K and including a large proportion of adakites, especially during the Quaternary (dacitic plugs). The authors tentatively relate this diversity to the development of a slab tear linked with the subduction of the fossil South China Sea ridge beneath the Baguio area.     

南海海—气通量交换研究进展

1998年的“南海季风试验（SCSMEX）”已经过去10年了,SCSMEX启动的南海海—气通量试验研究也有10个年头。在SCSMEX和国家自然科学基金面上项目“南海季风爆发期近海面层通量观测和湍流结构的观测研究”支持下,10年来在西沙实施了3次（1998年、2000年、2002年）海—气通量观测试验,开展了试验资料分析研究,重点是西南季风爆发前后海—气通量交换过程研究,辐射通量、感热通量、潜热通量、动量通量随天气条件的变化研究,海—气通量日变化,通量交换系数以及通量变化对低层大气、上层海洋的影响研究。对10年来南海通量研究作一回顾,对未来的通量观测研究计划特别是2008“亚洲季风年”西沙通量观测提出一些建议。     

南海海-气通量交换研究进展

1998年的"南海季风试验(SCSMEX)"已经过去10年了,SCSMEX启动的南海海-气通量试验研究也有10个年头.在SCSMEX和国家自然科学基金面上项目"南海季风爆发期近海面层通量观测和湍流结构的观测研究"支持下,10年来在西沙实施了3次(1998年、2000年、2002年)海-气通量观测试验,开展了试验资料分析研究,重点是西南季风爆发前后海-气通量交换过程研究,辐射通量、感热通量、潜热通量、动量通量随天气条件的变化研究,海-气通量日变化,通量交换系数以及通量变化对低层大气、上层海洋的影响研究.对10年来南海通量研究作一回顾,对未来的通量观测研究计划特别是2008"亚洲季风年"西沙通量观测提出一些建议.     

Climatic Characteristics of Binary Tropical Cyclones in the Northwest Pacific Ocean

Based on typhoon best track data of China Meteorological Administration and NCEP global reanalysis data, this study analyzed the characteristics of binary tropical cyclones (TC) in the Northwest Pacific Ocean during 1951 to 2014 by using the objective determine standard. When the distance between the two TCs d≤ 1 800 km, they are defined as binary tropical cyclones or binary typhoons. And binary typhoons are divided into two different types which are typical binary typhoons and atypical binary typhoons. The climatic characteristics of binary tropical cyclones are as follows: There were 699 pairs of binary typhoons in Northwest Pacific Ocean during 1951 to 2014. In these cases, there were 446 pairs of typical binary typhoons and 253 pairs of atypical cases, occupying 63.8% and 36.2%, respectively. The proportion of typical cases increased with the shortest distance decreasing, while the proportion of atypical cases decreased with the shortest distance decreasing. When the speed of typical binary typhoons moving towards each other reached the peak, binary typhoons mainly showed the east to west direction. At this time, typhoons were controlled by easterly stream of the southern edge of the subtropical high. In this situation, the east typhoon moved toward the west typhoon quickly. When the anticlockwise angular velocity of typical binary typhoons reached the peak, binary cases distributed northeast to southwest or east-northeast to west-southwest, appearing in west and southwest edge of the subtropical high and mainly being controlled by southeasterly stream, thus benefiting the anticlockwise rotation between the typical binary typhoons.     

南海东北陆坡断裂特征及其对盆地演化的控制作用

南海东北陆坡断裂发育,主要有北东、北西、近南北和近东西向的4组断裂,按性质分则有张性、压性和走滑等。主干基底断裂有F1、F2、F3、F4、F5、F6、F7、F8、F9、F10等,这些断裂规模较大并决定了珠江口盆地白云凹陷、尖峰北盆地、笔架盆地和台西南盆地发育和演化。受主干断裂的控制,尖峰北盆地经历了断陷、坳陷、区域沉降3期演化,发育两套构造层;而笔架盆地则经历了渐新世断陷、渐新世末—中中新世坳陷和晚中新世—全新世构造反转3期演化,发育两套构造层。