Organic matter source and thermal maturity within the Late Cretaceous Niobrara Formation,U.S. Western Interior

The Late Cretaceous sedimentary record of the North American Western Interior Seaway is characterized by cyclic deposition of organic carbon-rich sediments. One notable interval during the late Coniacian-Santonian is recorded by the Niobrara Formation. The organic carbon-rich interval within the Niobrara Formation has been identified as Oceanic Anoxic Event (OAE) 3. Understanding the reason for this distribution of organic carbon within the Niobrara Formation requires a refined understanding of the source and maturity of the organic matter. In this study, we present lipid biomarker records from the USGS Portland #1 core (Cañon City, CO) to constrain the thermal maturity of the organic matter and the differing contributions of organic matter sources. Sterane and hopane thermal maturity indices indicate that the samples are somewhat immature with respect to oil formation and that there is strong agreement between different proxies for thermal maturity. Based on the distribution of n-alkanes, steranes, and hopanes, there is a significant increase in the contribution of algal organic matter during and after OAE 3, coeval with increased organic carbon accumulation. Although a consistent terrestrial contribution is observed, it is only a minor source of organic matter at the Portland core location and does not drive increased organic matter accumulation during OAE 3. Of particular note is the consistent influence of even-over-odd predominantly mid-chain length (C₂₁ to C₂₅) organic matter. This observation within the brackish to marine, not methanogenic WIS represents an expansion of the depositional settings in which even-over-odd predominance has been observed in mid-chain length n-alkanes. Pristane (Pr) and phytane (Ph) abundances are inconsistent with a redox control on Pr/Ph ratios and suggest an increase in the delivery and/or preservation of phototrophic organic matter as the source for pristane and phytane in the Portland core.     

海洋电子政务数字认证框架研究

纵观海洋信息化的发展,海洋电子政务的建设将成为今后一个时期海洋信息化工作的重点。本文根据海洋信息化建设的要求,在国家电子政务PKI体系总体框架下,详细论述了PKI体系的密码体制、可认证性及其基本组成。通过对现有PKI体系信任模型的分析,结合我国海洋管理的模式和应用需求,指出了海洋电子政务PKI体系最简单最理想的信任模型是采用严格层次结构。介绍了海洋数字认证机构设立的形式,指出建立中国海洋数字认证中心是建立海洋电予政务PKI体系的核心,是实现海洋电子政务的基础,是国家电子政务PKI体系的重要组成部分。     

胶州湾生态环境分析预警系统——主要营养盐月际变化及其成为生物生长限制因素的概率计算

在胶州湾海洋生态环境GIS数据库的支持下，构筑了胶州湾主要营养盐硅、磷、氮的分析预警系统。该系统主要提供以下两大功能；（1）数据的显示、查询、更新和打印。（2）胶州湾内次月硅、磷、氮的预测值及硅、磷、氮成为抑制海洋浮游植物生长限制因素的概率计算。当上述概率超过了给定的阈值时，系统将发生警限。     

东太平洋CC区板块构造和多金属结核资源效应探讨

利用东太平洋CC区多波束海底地形测量、结核覆盖率深拖系统探测、结核丰度地质采样和地球物理地震勘探资料,运用板块构造和沉积动力学理论,并与丰度趋势面和神经网络分析结果对比,对东太平洋CC区构造与多金属结核资源效应关系进行了探讨,并认为:(1)富集在研究区约200亿t结核的最主要控制因素是东太平洋海隆、莱恩山脉、克拉里昂-克利伯顿大断裂(Clarion-Clipperton Fracture Zone),东、西、南、北的四个构造单元为结核大量富集起到了框架性的关键作用;(2)本区经历了和遵循着海底扩张的基本过程,这个过程对结核物质来源、成矿作用、结核分布有重大影响,结核丰度、覆盖率与地形变化非常一致,重大相变距离为10～15km,基底自形成以来一直影响着地表结核;(3)地球深部地质作用过程对结核成矿作用也有一定影响,影响因素可能涉及基底岩浆房及其大小等.     

多金属结核内部生长层组年代研究

根据结构构造、矿物组分、微体古生物组合不同,多金属结核内部可划分为三个生长层组,从内到外依次为：第Ⅰ生长层组、第Ⅱ生长层组、第Ⅲ生长层组。运用古生物地层学方法,对其中微体古生物化石（硅藻、超微、放射虫）进行综合分析,确定三个生长层组的生长年代为：第Ⅰ生长层组形成年代为渐新世到早中新世,其顶界年龄不晚于１８Ｍａ,第Ⅱ生长层组形成年代为早中新世末期到上新世早期,第Ⅲ生长层组时代为上新世早期到第四纪     

东太平洋锰结核中叠层石纹层韵律的研究

综合运用反光显微镜、扫描电镜、透射电镜等手段研究了东太平洋深海锰结核中微小叠层石纹层的韵律。研究表明, 锰结核中叠层石纹层是超微生物韵律性生长的结果, 而且在锰结核的磨光面上清楚地显示出纹层、纹层组和纹层带三个级别的生长韵律。每个纹层、纹层组和纹层带的平均厚度分别为 ５１６ μｍ 、５５１ μｍ 和 ５５６ μｍ 。根据微生物生长的一般规律以及锰结核中的间断现象倾向性地认为, 锰结核中纹层的生长周期可能在数十年或近百年。     

Relationship between mn nodule abundance and other geological factors in the northeastern pacific: Application of gis and probability method

The aims of this study are 1) to construct a database using geostatistics and Geographic Information System (GIS), and 2) to derive the spatial relationships between manganese nodule abundance and other geological factors such as metal grade, slope, water depth, topography, and acoustic characteristics of the sub-bottom. Using GIS, it is possible to analyze a large amount of data efficiently, and to maximize the practical application, to increase specialization, and to enhance the accuracy of the analyses. The greater the copper and nickel grade, the higher the rating. The distribution pattern of nickel grade is similar to that of copper grade. The slopes are generally less than 3° except for seamounts and cliff areas. The rating shows no correlation with slope. The rating is highest for slopes between 2.5 and 3.5° in block N1 and between 4.0 and 4.5° in block N3. The topography is classified into five groups: seamount, hill crest, hill slant, hill base or plain, and seafloor basin or valley. The rating proves lowest for seamount and hill crest. Our results show that the rating increases with the water depth in the study area. Nodule abundance dose not show any significant relationship with the thickness of the upper transparent layer in the study area.     

Characteristics of Seafloor Morphology and Ferromanganese Nodule Occurrence in the Korea Deep-sea Environmental Study (KODES) Area,NE Equatorial Pacific

Abstract

Seafloor morphology and ferromanganese nodule occurrence were studied using a multibeam side scan sonar (SeaBeam, 2000) and a deep-sea camera system in the Korea Deep-sea Environmental Study (KODES) area, northeast equatorial Pacific. Seafloor morphology and nodule abundance are highly variable even in this small study area. The NNE-SSW oriented hills are parallel and about 100–200 m high. Valleys are very flat-floored, while hilltops are rugged with depressions of tens of meters. Cliffs to about 100 m bound the valleys and the hills. The study area can be classified into three types based both on nodule occurrence and seafloor morphology, mostly G- and B-types and some M-type. G-type is characterized by high nodule abundance, ubiquitous bioturbation, and flat seafloor morphology, while B-type is characterized by irregular-shaped nodules, variable nodule abundance, occurrence of giant nodules and sediment lumps, rugged bottom morphology with depressions, and white calcareous surface sediments. Medium nodule abundance and a generally flat seafloor characterize M-type. G-type occurs mostly in the valley regions, while B-type is on the hilltop areas. M-type is located between the hilltop and the valley. Tectonic movement of the Pacific plate resulted in the elongated abyssal hills and cliffs. The rugged morphology on hilltops resulted from erosion and redistribution of surface siliceous sediments on hilltops by bottom currents, outcropping of underlying calcareous sediments, and dissolution of the carbonate sediments by corrosive bottom water undersaturated with CaCO₃. Sediment eroded from the hills, which is relatively young and organic-rich, is deposited in the valleys, and diagenetic metal supply to manganese nodules in the valley area is more active than on the hills. We suggest that tectonic movement ultimately constrains morphology, surface sediment facies, bottom currents and sediment redistribution, bioturbation, thickness of the sedimentary layer, and other conditions, which are all interrelated and control nodule occurrence. The best potential area for mining in the study area is the G-type valley zones with about 3–4 km width and NNW-SSE orientation.     

Alterations in Geochemical Associations in Artificially Disturbed Deep-Sea Sediments

In view of the role of Sediment geochemistry in regulating the benthic ecosystem, diagenetic remobilization of dissolved constituents, bottom water redox, and regeneration of benthic fluxes, surficial sediments in and around the track disturbed by a “benthic disturber” were studied for metal variation in three phases: (1) before the disturbance, (2) immediately after the disturbance, and (3) during monitoring of restoration after ~44 months, from the same locations. Minor variations in metal concentrations before the disturbance ere noticed indicating the homogeneity in the area or supply from similar source areas. Terrigenous fraction determined normatively from titanium contents in these sediments ranges between 40 and 47%. Most of the elements analyzed showed reduced average concentrations immediately after the disturbance suggesting physical removal and resedimentation in other areas with the migration of the plume. All the elements showed positive relation and coherence in the sediments collected after the disturbance, irrespective of their susceptibility to changes in provenance and depositional environment, whereas elemental associations during the predisturbance and monitoring periods can be explained by the known geochemical processes. The changes in Al, Ti, excess aluminium contents, their interelement relations, and factor analyses, suggest the possible transformation of clay mineral type due to the benthic disturbance that would involve changes in surface chemistry of clays. Interelement relations among redox-sensitive elements have also changed with time. This includes decoupling of Co from Mn after 44 months, probably due to the varying oxidation kinetics of two major oxides, Fe and Mn. Model calculations suggest increased diagenetic remobilization rates of Mn during the monitoring phase. Substantial increase in redox-sensitive elements, especially Fe and Mn indicate oxygenation of bottom water due either to reduced activity of benthic burrowing organisms or to renewal of oxygen-rich Antarctic Bottom water (AABW). Increase in these elements is consistent with the results of the HEBBLE experiment, where the burrows seem to protect these elements from strong bottom currents. Restoration of predisturbance values in the terrigenous component is attributed to the influence of shifts in the direction of bottom flow and suggests that bottom currents would play a major role in restoring the lithogenic component by transporting it from other locations within the Basin during commercial mining operations.     

Ocean manganese nodule and sediment reference materials

In this article, sampling locations, sample types, sample processing methods, and certified values of ocean manganese nodule and sediment reference materials available throughout the world are briefly described. Recommended or information values of major, minor, and trace constituents in those samples have also been collected, and a review of the main characteristics of their property values is presented.