中国近海以及邻近海域海洋再分析产品(CORA)中季节内变化的评估

A regional reanalysis product—China Ocean Reanalysis(CORA)—has been developed for the China's seas and the adjacent areas. In this study, the intraseasonal variabilities(ISVs) in CORA are assessed by comparing with observations and two other reanalysis products(ECCO2 and SODA). CORA shows a better performance in capturing the intraseasonal sea surface temperatures(SSTs) and the intraseasonal sea surface heights(SSHs) than ECCO2 and SODA do, probably due to its high resolution, stronger response to the intraseasonal forcing in the atmosphere(especially the Madden-Julian Oscillation), and more available regional data for assimilation. But at the subsurface, the ISVs in CORA are likely to be weaker than reality, which is probably attributed to rare observational data for assimilation and weak diapycnal eddy diffusivity in the CORA model. According to the comparison results, CORA is a good choice for the study related to variabilities at the surface, but cares have to be taken for the study focusing on the subsurface processes.     

琼州海峡潮流能资源的数值模拟评估

近年来,我国能源消耗量不断的增长使我们更加重视可再生能源的开发利用,而我国近海拥有复杂的海岸线和广阔的大陆架,其中许多海域蕴藏着丰富的潮流能资源。潮流能资源评估则是其电站站址选择、发电量预测等工程设计的首要工作。结合两个站位的潮流实测数据,本文利用FVCOM海洋环流数值模式较好的模拟了琼州海峡潮波传播状况,分析了该海域潮流能资源水平分布规律和时间变化特征,初步估算了该水道的潮流能的理论蕴藏量,并采用FLUX方法对该水道的技术可开发量进行了评估。结果表明,琼州海峡中心海域功率密度高,两岸资源低;可能最大流速、大潮年平均最大功率密度、小潮年平均功率密度和年平均功率密度等特征值分布基本相似;其丰富区域出现在海峡东口南部海域以及海峡中部海域,其中东口南部海域可能最大流速可达4.6 m/s,表层流大潮年平均最大功率密度为5996 W/m²,小潮平均最大功率密度仅为467 W/m²,年平均功率密度为819 W/m²,代表点超过0.7 m/s的潮流流速年统计时间约为4717 h;海峡潮流能资源理论蕴藏量为189.55MW,利用FLUX、FARM、GC方法得到该水道的潮流能可开发量分别为249GW/yr、20.2GW/yr和263GW/yr。     

黑潮延伸体上游中尺度涡场的年代际振荡及其相关机制

黑潮延伸体上游区域的中尺度涡场的涡动能和涡特征尺度存在显著地年代际振荡,和黑潮延伸体路径的年代际变化有很好的相关性。当黑潮延伸体路径比较稳定时,其上游区域涡动能比较高,涡特征尺度比较大,反之相反。通过对黑潮延伸体上游区域的中尺度涡场进行集合分析发现:当黑潮延伸体处于稳定状态时,上游涡场几乎是各向均匀地,有轻微的径向伸长;而当黑潮延伸体处于不稳定状态时,上游的中尺度涡场有显著地纬向伸长。对与中尺度涡场的产生相关的线性斜压不稳定和正压不稳定进行了计算分析,结果显示,线性斜压不稳定不是控制中尺度涡场年代际变化的机制,而正压不稳定对中尺度涡场的年代际变化有积极的贡献。不稳定产生的中尺度涡之间存在非线性涡-涡相互作用。     

星载SAR对雨团催生海面风场的观测研究

雨团或对流雨是热带与亚热带地区的主要降雨形式,较易被高分辨率星载合成孔径雷达（SAR）探测到。SAR图像上的雨团足印是由大气中雨滴的散射与吸收、下沉气流等共同导致形成的。本文以RADARSAT-2卫星100 m分辨率的SAR图像上雨团引起的海面风场及其结构反演与解译作为实例进行分析。使用CMOD4地球物理模式函数,分别以NCEP再分析数据、欧洲MetOp-A卫星先进散射计（ASCAT）和中国HY-2卫星微波散射计的风向为外部风向,进行了SAR图像的海面风场反演。反演的海面风速相对于NCEP、ASCAT和HY-2的均方根误差（RMSE）分别为1.48 m/s,1.64 m/s和2.14 m/s。SAR图像上一侧明亮另一侧昏暗的圆形信号图斑被解译为雨团携带的下沉气流对海面风场（海面粗糙度）的改变所致。平行于海面背景风场其通过雨团圆形足印中心的剖面上的风速变化可拟合为正弦或余弦曲线,其拟合线性相关系数均不低于0.80。背景风场的风速大小、雨团引起的风速大小以及雨团足印的直径可利用拟合曲线获得,雨团足印的直径大小一般为数千米或数十千米,本文的8例个例解译与分析均验证了该结论。     

末次冰盛期后黄河三角洲沉积物的磁性特征及其沉积环境

On the basis of measuring the magnetic parameters of sediment in Core YDZ1, combined with a grain size analysis and Carbon-14 dating, the magnetic properties of sediment and sedimentary environment in the Huanghe(Yellow River) Delta area after the last glacial maximum have been studied. The results show that the ferrimagnetic minerals of a pseudo single domain and multi domain particles dominate the magnetic properties of sediment in Core YDZ1. The imperfect anti ferrimagnetic minerals have more contribution on sediment in a depth of 24.0–22.1 m, and more stable-single domain and pseudo single domain particles exist. The susceptibility of anhysteretic remanent magnetization and the ratio of the susceptibility of anhysteretic remanent magnetization to saturation isothermal remanent magnetization show a decrease trend below depth of 24 m, a marked increase trend in a depth of 24.0–13.5 m, and a rapid decrease at depth of 13.5 m, then a fluctuation trend upward. The above two magnetic parameters and the ratio of the susceptibility of anhysteretic remanent magnetization to the mass susceptibility can be regarded as the proxy indicators for the content of clay(4 μm)and the fine-grained size(32 μm). The sedimentary environment after the last glacial maximum in the Huanghe Delta area has experienced the fluvial facies, the tidal flat facies, the neritic facies, the pro delta facies, the delta front facies and the floodplain facies. Thickness of the Holocene transgression layer is 10.5 m and the depth of substrate is about 24 m according to the YDZ1 core. The sedimentary dynamic has a variation trend with strongweak-strong, which has been proved by the Flemming triangular schema.     

南大洋太平洋扇区中尺度涡旋的统计特性及其变化

中尺度涡旋在南大洋海洋动力学中具有重要地位,其对气候变化的响应表现也引起了海洋学家与气候学家的广泛关注。本文利用涡动动能与涡旋自动探测技术两种方法对南大洋太平洋扇区的涡旋特性及其变化进行了分析。与前人结果相一致的是,高值的涡动动能主要集中在南极极锋海区,并且自西向东逐渐减弱。在过去的20年里,涡动动能在太平洋扇区的显著增强也集中在中西部海域,这里也是南极绕极流斜压性较强的海域。涡旋统计特性揭示了涡动动能的空间分布及其年际变化主要归因于涡旋振幅与旋转速度,而并非涡旋个数或者涡旋半径。这些结果进一步确认了对应于南半球环状模正位相的绕极西风异常改变了南大洋的涡旋特性,从而表现出涡旋活跃性增强。     

Paleo-redox depositional conditions inferred from trace metal accumulation in two Cretaceous-Paleocene organic-rich sequences from Central Egypt

Cretaceous-Paleocene organic-rich sediments in Egypt occur as an east-west trending belt extending from the Quseir-Safaga district (Red Sea) to the Kharga-Dakhla (Western Desert) region. They are associated with the Duwi Formation (phosphate-bearing) and the overlying Dakhla Formation (deeper epicontinental shale/marl). This study aims to reconstruct the paleo-redox conditions during deposition of these thermally immature organic-rich sediments using carbon-sulfur-iron systematics and trace metal proxies in two cores, one each from the Quseir and Abu Tartur areas. Paleoproductivity, based on P content, seems to have been higher in the Quseir section than in the Abu Tartur section. The Quseir section also records a relatively greater occurrence of anoxic conditions during the accumulation of these sediments than the Abu Tartur section. This difference is indicated by its markedly higher total organic carbon (TOC) content as well as higher contributions of redox-sensitive and sulfide-forming metals (Mo, U, Ni, V, and Co). A weak correlation exists between S and TOC, and a positive S intercept (>1) was observed in most of the rock units of the study sections. A high consistency between the TOC-S-Fe relations and trace metals findings was found. The uppermost Duwi and the lowermost Dakhla strata, which have the highest TOC and represent a maximum sea transgression during the Late Cretaceous, have the highest contents of redox-sensitive trace metals. The carbonate-dominated transgressive Baris and Beida members of the Dakhla Formation record relatively stronger oxygen-depleted conditions during their accumulation than others, which led to relatively higher TOC contents and redox-sensitive metal accumulations. A scenario for the environmental conditions that existed during the deposition of these organic-rich successions, based on compiled trace metals and TOC-S-Fe implications, is reconstructed here.     

Origin of the Breno and Esino dolomites in the western Southern Alps (Italy): Implications for a volcanic influence

The Esino Limestone of the western Southern Alps represents a differentiated Ladinian-Lower Carnian (?) carbonate platform comprised of margin, slope and peritidal inner platform facies up to 1000 m thick. A major regional subaerial exposure event lead to coverage by another peritidal Lower Carnian carbonate platform (Breno Formation). Multiphase dolomitization affected the carbonate sediments. Petrographic examinations identified at least three main generations of dolomites (D1, D2, and D3) that occur as both replacement and fracture-filling cements. These phases have crystal-size ranges of 3–35 μm (dolomicrite D1), 40–600 μm (eu-to subhedral crystals D2), and 200 μm to 5 mm (cavity- and fracture-filling anhedral to subhedral saddle dolomite D3), respectively.The fabric retentive near-micritic grain size coupled with low mean Sr concentration (76 ± 37 ppm) and estimated δ¹⁸O of the parent dolomitizing fluids of D1 suggest formation in shallow burial setting at temperature ∼ 45–50 °C with possible contributions from volcanic-related fluids (basinal fluids circulated in volcaniclastics or related to volcanic activity), which is consistent with its abnormally high Fe (4438 ± 4393 ppm) and Mn (1219 ± 1418 ppm) contents. The larger crystal sizes, homogenization temperatures (D2, 108 ± 9 °C; D3, 111 ± 14 °C) of primary two-phase fluid inclusions, and calculated salinity estimates (D2, 23 ± 2 eq wt% NaCl; D3, 20 ± 4 eq wt% NaCl) of D2 and D3 suggest that they formed at later stages under mid-to deeper burial settings at higher temperatures from dolomitizing fluids of higher salinity, which is supported by higher estimated δ¹⁸O values of their parent dolomitizing fluids. This is also consistent with their high Fe (4462 ± 4888 ppm; and 1091 ± 1183 ppm, respectively) and Mn (556 ± 289 ppm and 1091 ± 1183 ppm) contents, and low Sr concentrations (53 ± 31 ppm and 57 ± 24 ppm, respectively).The similarity in shale-normalized (SN) REE patterns and Ce (Ce/Ce*)_SN and La (Pr/Pr*)_SN anomalies of the investigated carbonates support the genetic relationship between the dolomite generations and their calcite precursor. Positive Eu anomalies, coupled with fluid-inclusion gas ratios (N₂/Ar, CO₂/CH₄, Ar/He), high F⁻ concentration, high F/Cl and high Cl/Br molar ratios suggest an origin from diagenetic fluids circulated through volcanic rocks, which is consistent with the co-occurrence of volcaniclastic lenses in the investigated sequence.     

A novel method to estimate mineral compositions of mudrocks: A case study for the Canadian unconventional petroleum systems

The mineral composition of mudrocks is an essential attribute in controlling the reservoir quality of unconventional petroleum systems. The present study introduces a semi-quantitative method to estimate mineral phases of mudrocks in various Canadian unconventional hydrocarbon systems using total elemental analysis (inductively coupled plasma-mass spectrometry (ICP-MS)) and Rock-Eval data (total organic carbon (TOC) and mineral carbon (MinC)).This method involves statistical analysis based on a sound knowledge of hydrocarbon source rock inorganic geochemistry. The workflow can be divided into four steps: (i) converting major elements (Si, Al, Fe, K, Na, Ca, Mg, Ti, and P) to their oxides, (ii) inferring modes of occurrence of elements using statistical analysis of geochemical data (major elements, TOC, and MinC), (iii) identifying the mineral types (oxide, aluminosilicates, carbonates, sulfide, and phosphate) according to elemental occurrences and calculating mineral phase concentrations, and (iv) verifying the results by comparing to XRD data on selected samples. The results, especially for brittle minerals such as quartz, carbonates (e.g. calcite, dolomite, and ankerite), and pyrite, show that the estimated mineral compositions correspond closely and consistently with measured mineralogy obtained from XRD. This method takes advantage of bulk geochemical data already available for hydrocarbon potential and chemostratigraphic studies, without devoting additional samples and cost for XRD analysis.     

南海中尺度涡强度的季节和年际变化分析

为了研究南海中尺度涡强度的季节和年际变化规律,利用Matlab提取50 a(1958~2007年)简单海洋资料同化(Simple Ocean Data Assimilation,SODA)月平均数据集中流场和海表面高度场数据,应用一个涡旋自动探测算法对南海中尺度涡初始生成位置进行分析,并分析了海表面高度异常均方根值的季节变化和年际变化。结果表明:50 a里南海中尺度涡主要分布在吕宋岛西北海域、吕宋岛西南海域和越南以东广大海域,秋、冬季中尺度涡能量较高,春季中尺度涡最弱,中尺度涡强度高值区年际变化明显。从季节变化上看,海面高度异常均方根春、夏季最小,秋冬季最大;从年际变化上看,与同时期Nino3指数有显著负相关,周期大约为3 a。