Mineralogy and geochemistry of atypical reduction spheroids from the Tumblagooda Sandstone,Western Australia

Reduction spheroids are small-scale, biogenic, redox-controlled, metal enrichments that occur within red beds globally. This study provides the first analysis of the compositionally unique reduction spheroids of the Tumblagooda Sandstone. The work aims to account for their composition and consequently improve existing models for reduction spheroids generally, which presently fail to account for the mineralogy of the Tumblagooda Sandstone reduction spheroids. Interstitial areas between detrital grains contained in the cores of these reduction spheroids are dominated by microplaty haematite, in addition to minor amounts of svanbergite, gorceixite, anatase, uraninite, monazite and illite. The haematite-rich composition, along with an absence of base metal phases and the vanadiferous mica roscoelite, makes these reduction spheroids notable in comparison to other global reduction spheroid occurrences. Analyses of illite crystallinity provide values for samples of the Tumblagooda Sandstone host rock corresponding to heating temperatures of ca 200°C. Consequently, while Tumblagooda Sandstone reduction spheroids formed via the typical metabolic processes of dissimilatory metal-reducing bacteria, the combination of a unique mineralogy and illite crystallinity analysis provides evidence of more complex late-stage heating and reoxidation. This has not previously been recognised in other reduction spheroids and therefore expands the existing model for reduction spheroid genesis by also considering the potential for late-stage alteration. As such, future reduction spheroid studies should consider the potential impact of post-formation modification, particularly where they are to be used as evidence of ancient microbial processes; such as in the search for early evidence of life in the geological record on Earth or other planets. Additionally, because of their potential for modification, reduction spheroids serve as a record of the redox history of red beds and their study could provide insights into the evolution of redox conditions within a given red bed during its diagenesis. Finally, this paper also provides insights into the relatively understudied diagenetic history of the Tumblagooda Sandstone; supplying the first reliable and narrow constraints on its thermal history. This has important implications for the thermal history of the Carnarvon Basin and its petroleum prospectivity more broadly.     

非饱和红黏土三轴试验研究

红黏土强度特性直接关系到路基的稳定和边坡坡度的选取,是地基工程、边坡工程和洞室工程设计计算的重要参数。以贵阳红黏土为例,对非饱和红黏土的强度特性进行了常规三轴试验研究。根据试验结果,分析了原状红黏土和压实红黏土的应力-应变关系及破坏类型,提出了压实红黏土的应力-应变关系曲线的数学模型,得出了压实红黏土抗剪强度参数与物理指标指标之间的关系。     

湖南古丈红石林地质遗迹形成条件及发育过程初探

介绍了古丈红石林的地质环境背景,分析红石林地质遗迹形成的物质基础、内外动力条件,初步论证了地质遗迹形成的四个条件和三个发育阶段,并对其保护与开发提出了意见和建议。     

运用混合回归模型预报赤潮

通过先行建立每个影响因子的非线性回归模型,然后作总体线性回归,首次给出了用混合回归模型预报赤潮的方法。这样就改进了现有的用多元线性回归模型进行赤潮预报的方法,提高了赤潮预报的准确性。     

Studies on Biquaternary Ammonium Salt Algaecide for Removing Red Tide Algae

Phaeoecystis globosa, one of the most widespread marine Haptophytes, is a newly discovered species of algae in China. During the period from the autumn of 1997 to the spring of 1998, a heavy harmful algal bloom (HAB) of P. globosal first occurred in the coastal waters of East China Sea and South China Sea, which caused a great impact on the local aquiculture industry [1, 2]. Since then, this HAB has frequently attacked this area. Alexandrium tamarense can produce paralytic shellfish po…     

1998年冬春季粤港赤潮爆发海区异常高SST成因分析

根据海洋站、气象站的观测资料和历史文献,较系统地分析了1998年冬春季粤港发生大规模赤潮期间广东沿海海表水温（SST）变化特点及异常高SST的原因。结果表明,1997年4月至1998年6月,月平均SST呈准同步变化趋势。赤潮大爆发期间各站的季平均海表水温距平（SSTA）为1．1℃～1．5℃,达到异常高SST标准。其中月平均SSTA达1．5℃-2．0℃。SSTA有两个明显峰期分别出现于1997年12月-1998年1月和1998年4-5月。异常高SST的主要原因是全球气候变暖,受强EI Nino影响、冬季风异常弱、南海高压持续偏强。     

广东沿海赤潮与海洋水文气象关系研究

根据广东沿海发生赤潮的实测资料,重点分析了1997年10月至1998年5月广东沿海赤潮发生与海洋水文气象的关系.结果表明：棕襄藻（Phaecystis cf globosa Scherffel）和三宅裸甲藻（Gynmodiniu mmikimoloi）最大增殖速率的发生条件为：海水温度（以下均是日平均值）21.9℃～26.9℃.盐度26.68～32.01,气温22.9℃～27.1℃、风速0.2-4.3m/s、气压1 002.2～1 011.9hPa、相对湿度83%～94%.认为1997-1998年赤道太平洋上层海洋水温异常变化,导致1998年中国东南沿海水温和气温偏高,风速偏弱,盐度偏低,相对湿度偏高,气压偏低,容易发生赤潮;而降水量多少对1998年广东沿岸海域赤潮形成和发展也有重要影响.发现春夏季当海平气压和盐度出现下降趋势,气温、水温和相对湿度呈上升趋势,风速呈减弱趋势时容易发生赤潮,赤潮发生海域主要位于500 hPa图上的副高北沿,赤潮发生海域均位于槽前.在850hPa图上,华南地区则出现较强的切变线环流.地面天气图上,赤潮发生时在南岭附近有锋面系统存在,海面风速较弱,风向偏东.     

赤潮预测的人工神经网络方法初步研究

赤潮是一种由多因素综合作用引发的生态异常现象,具有突发性及非线性等特点。对其进行预测预报一直是海洋科学研究的热点。探讨了应用人工神经网络原理进行赤潮预测的方法,简要介绍了BP和RBF算法的基本原理,用2种算法对不同海域赤潮生物与环境因子之间非线性和不确定性的复杂关系进行学习训练和预测检验,并与传统的统计方法进行了比较。结果表明：人工神经网络方法在模拟和预测方面优于传统的统计回归模型,具有较强的模拟预测能力及实用性,值得进一步探索。     

营养盐对海洋浮游植物生长的影响--数学模型研究

概述了海水中营养盐和细胞体内营养元素含量对海洋浮游植物生长的影响，并阐述了数学模型方法描述海洋浮游植物生长的发展过程，指出在现有生物生长模型基础上，建立重要营养物质迁移，转化等生态学过程与赤潮生物生长关系相结合的数学模型是建立现场环境条件下海洋浮游植物生长数学模型，进而揭示有害赤潮发生的生态学机理等的必要科学基础。     

前处理步骤与方法对风成红粘土粒度测量的影响

中国北方晚第三纪红粘土堆积为研究古气候与古环境提供了很好的地质记录,其粒度测量作为一个重要的代用指标被广泛应用。粒度测量结果受到前处理方法的影响,但是,现在各个实验室的前处理方法还不一致,这就为粒度数据分析和古气候古环境解释带来了困难。在黄土高原从北到南选择了3个具有代表性的红粘土剖面,对每个剖面从下向上取10块样品总计得到30块样品,对每个样品用不同的前处理方法与步骤（包括化学分离石英的方法）处理后用激光粒度仪进行颗粒测量。结果表明,前处理方法与步骤可以使同一个样品粒度参数发生几倍甚至于二十几倍的变化。综合理论和经验分析,推荐了一种较好的进行风尘堆积粒度测量的前处理方法（正文中方法C）。化学分离的纯石英的粒度分布比本文推荐的方法处理同一个样品的粒度结果偏粗,表明在提纯石英的过程中较细的不稳定矿物已经被剔除。