暗额藻属Aneumastus在中国的出现及其地层意义(硅藻门Bacillariophyta）

从内蒙古克什克腾旗浩来呼热乡硅藻土层中获得丰富的硅藻化石, 采用激光共聚焦显微扫描技术(Confocal Laser Scanning Microscopy)的研究方法, 对其中由Mann & Stickle (1992)确立的新属暗额藻属Aneumastus在我国地层中的出现, 及其在分类学上的意义进行了深入的讨论。该属的深入研究对今后古湖沉积物的地层及古生态研究有重要的现实意义。     

中国二迭纪床板珊瑚化石的地层分布、分带与动物地理分区的初步看法

一、前言中国二迭纪床板珊瑚化石分布广泛,数量丰富,层位稳定,是划分二迭纪地层,主要是早二迭世地层的标准化石之一。早在本世纪三十年代,我国的一些地层古生物工作者就将其列为早二迭世的分带化石。新中国成立之后,二迭纪床板珊瑚化石的研究工作有了很大的发展。据不完全统计,到目前为止,已发表床板珊瑚7属55种。虽然这些资料仅代表我国二迭纪床板珊瑚化石的很小一部分,但就现有资料进行初步综合整理和研究,提出床板珊瑚化石在我国二迭纪地层中的分布规律和动物地理分区,对我国二迭纪地层划分和对比工作将会起一定的促进作用。     

新疆石炭纪腕足类组合特征

新疆石炭纪地层在各大山系中皆有广泛分布,岩性、岩相十分复杂,古生物化石均较发育,以海生动物最为繁盛,现已发现十几个门类的化石。腕足动物主要见于海相和海陆交互相的地层中,由于属种繁多,数量极为丰富,化石分布广泛,多保存完美,因此在地层划分对比中起着十分重要的作用。     

兰州--民和盆地首次发现白垩纪恐龙足印化石

兰州—民和盆地是我国西北地区的一个较大的中新生代盆地,广泛分布着巨厚的白垩纪—第三纪河湖相地层。其中,第三纪地层中的生物化石十分丰富,而白垩纪地层中十分稀少,除微体化石外,未发现任何具有地层意义的宏观生物化石。从而影响对该地区中生代生物演化、地层划分...     

贵州石炭、二叠系床板珊瑚化石

一、前言 贵州石炭、二叠系床板珊瑚化石数量丰富,分布广泛,层位稳定,是划分对比石炭,二叠纪地层的重要化石之一。近几年来,笔者搜集和研究了我队历年来在区调工作中所采集的标本,已在《西南地区古生物图册一贵州分册》一书中报导了贵州石炭,二叠系床板珊瑚化石23属124种。但是,对化石的地层和地理分布还缺乏系统的总结。本文试图根据区域地质调查工作中的大量实测剖面及有关单位的工作成果,对贵州石炭、二叠系床板珊瑚化石的地层和地理分布作一次总结,以期对石炭、二叠纪地层划分,对比起一定的促进作用。     

青藏高原北部茅口晚期地层缺失研究

青藏高原北部二叠纪地层分布广泛,化石丰富,尤其是早—中二叠世地层层序完整,且产丰富的、珊瑚、腕足类等化石,晚二叠世地层分布较为零星,仅局部地区有保存。通过对1999年以来在青藏高原北部空白区开展的1/25万区域地质调查成果等资料的分析,结合大量的野外观察,发现中、晚二叠世之间普遍存在着沉积间断,表现为地层之间的不整合或假整合以及晚二叠世地层的大量缺失。与华南区对比,普遍缺失中二叠统茅口阶顶部的Yabeina生物化石带,相当于本带所代表的茅口晚期地层是缺失的,这对于建立青藏高原北部地层序列,探讨沉积—构造演化史均具有重要意义。     

中国黄土磁性地层与生物地层对比

本文统计了中国黄土地层中发现的哺乳动物化石并对一些发现较丰富哺乳动物化石的黄土剖面进行了磁性地层学研究，分析了磁性地层与生物地层对比结果，讨论了黄土层中哺乳动物化石的时空分布，以及有关气候环境问题。     

湘中、湘南早石炭世孢粉组合及其地层意义

一、引言湖南石炭系下统主要分布在湘中、湘南一带。最早由田奇(王崔乃)、王晓青等作过初步划分,其后吴望始及省地质局区调队进行了较详细的工作和划分,并获得了丰富的动、植物化石,确定了其地层时代。但对于该层位中的孢粉化石在本省尚无报道。这次获得的孢粉组合对我省和我国南方早石炭世孢粉植物群及生物地层的研究有其一定的意义。     

新疆奥陶纪、志留纪四射珊瑚特征及其地质地理分布

新疆的奥陶纪和志留纪地层较为发育,全疆各地都有,化石十分丰富、但出露面积不大,分布亦较零星。在奥陶纪和志留纪介壳相地层中含有比较多的四射珊瑚化石。通过参加编制西北地区古生物图册新疆分册工作,笔者对解放以来新疆区域地质调查和地质勘探工作中积累的大量地层古生物资料进行了系统的整理。本文是在综合上述大量资料,特别是在未刊资料的基础上,试图对新疆四射珊瑚化石在奥陶纪和志留纪地层中的分布及其特征作一探讨,从中总结出某些规律,以利于区域地     

松辽盆地中部东缘早自垩世地层研究的新进展

一、概况分布于松辽盆地中部东缘的早白垩世地层,在公主岭、刘房子、卡伦水库一带(图1)出露较全,前人对这套地层做的工作不多,除局部地段有钻孔控制外,尚无人做过系统的地表工作,研究程度较低。1983年至1984年吉林省地质矿产局区域地质矿产调查所六分队在进行1:20万怀德县幅地质调查工作中,对该区早白垩世地层测制了连续的剖面,采集了较丰富的化石,其中有叶肢     

山东山旺中新世硅藻土的纹层类型及成因

山东临朐山旺地区中新世山旺组硅藻土极为发育。通过对该地区硅藻土纹层的研究,确定其分类和成因,为进一步确立年纹层的存在、利用其进行高分辨率测年、探讨高频古气候旋回奠定基础。山旺组硅藻土的单层纹层厚度一般为100μm左右。依据纹层的物质成分,单层纹层可分为硅藻纹层、有机纹层和粘土纹层三种类型。各类单层纹层组合成为明暗相间的层偶,层偶厚度一般为100～400μm,常常表现为浅色的硅藻纹层逐渐向深色的粘土纹层或有机质纹层渐变过渡。纹层层偶可分为:薄层硅藻纹层-有机质层偶,厚层藻纹层-有机质层偶,薄层粘土纹层-有机质层偶,厚层粘土纹层-有机质层偶和硅藻纹层-粘土纹层层偶。山旺组硅藻土中不同类型的单层纹层以及层偶的形成主要受控于当时湖盆内粘土物质的沉积速率、硅藻的繁盛程度和有机物质的沉积和保存条件。     

腾冲上新统芒棒组地质时代及沉积环境

摘要：腾冲地区新生代地层分布广泛，其中又以芒棒组出露较为完整，由河流相、湖泊相及沼泽相碎屑岩夹火山岩中火山沉积岩组成，含丰富的植物化石和硅藻化石。依据化石研究及用K-Ar、Rh-Sr法测获同位素年龄，芒棒组应属新近纪上新世。植物化石显示腾冲地区上新世时期气候，比现今亚热带炎热干燥气候较温凉而湿润，反映该区从新近纪上新世至第四纪，气候有从凉变暖的演变趋势。     

Age assignment of a diatomaceous ooze deposited in the western Amundsen Sea Embayment after the Last Glacial Maximum

Reliable dating of glaciomarine sediments deposited on the Antarctic shelf since the Last Glacial Maximum (LGM) is challenging because of the rarity of calcareous (micro‐) fossils and the recycling of fossil organic matter. Consequently, radiocarbon (¹⁴C) ages of the acid‐insoluble organic fraction (AIO) of the sediments bear uncertainties that are difficult to quantify. Here we present the results of three different methods to date a sedimentary unit consisting of diatomaceous ooze and diatomaceous mud that was deposited following the last deglaciation at five core sites on the inner shelf in the western Amundsen Sea (West Antarctica). In three cores conventional ¹⁴C dating of the AIO in bulk samples yielded age reversals down‐core, but at all sites the AIO ¹⁴C ages obtained from diatomaceous ooze within the diatom‐rich unit yielded similar uncorrected ¹⁴C ages between 13 517 ± 56 and 11 543 ± 47 years before present (a BP). Correction of these ages by subtracting the core‐top ages, which probably reflect present‐day deposition (as indicated by ²¹⁰Pb dating of the sediment surface at one core site), yielded ages between ca. 10 500 and 8400 cal. a BP. Correction of the AIO ages of the diatomaceous ooze by only subtracting the marine reservoir effect (MRE) of 1300 a indicated deposition of the diatom‐rich sediments between 14 100 and 11 900 cal. a BP. Most of these ages are consistent with age constraints between 13.0 and 8.0 ka for the diatom‐rich unit, which we obtained by correlating the relative palaeomagnetic intensity (RPI) records of three of the sediment cores with global and regional reference curves. As a third dating technique we applied conventional radiocarbon dating of the AIO included in acid‐cleaned diatom hard parts extracted from the diatomaceous ooze. This method yielded uncorrected ¹⁴C ages of only 5111 ± 38 and 5106 ± 38 a BP, respectively. We reject these young ages, because they are likely to be overprinted by the adsorption of modern atmospheric carbon dioxide onto the surfaces of the diatom hard parts prior to sample graphitisation and combustion for ¹⁴C dating. The deposition of the diatom‐rich unit in the western Amundsen Sea suggests deglaciation of the inner shelf before ca. 13 ka BP. The deposition of diatomaceous oozes elsewhere on the Antarctic shelf around the same time, however, seems to be coincidental rather than directly related. Copyright © 2009 John Wiley & Sons, Ltd.     

A Mineralogical Study of Diatomite in Leizhou Peninsula

In this paper diatomite samples taken from the Leizhou Peninsula have been studied by chemical analysis, DTA, TG, XRD, IR ,SEM and X-ray Energy Spectroscopy.The study shows that the diatomaceous genera and species and their organic contents are variable with buried depth ,from Melosira to Stephanodiscus and then to Cyclotella. Various impurities in the samples, such as quartz, kaolinite and montmorillonite indicate different sedimentary environments. When heated, the diatom would change in shape due to the phase transformation in which amorphous silica crystallized from disordered opal to ordered cristobalite. The temperatures of phase transformation are different for various diatoms due to the presence of different impurities and constituents of diatomaceous genera and species.     

Diatom record from Lake Hovsgol, Mongolia, during the last 1 Ma: The results from the HDP-04 drill core

Quantitative diatom abundance and species composition was studied in the longest 81-m Lake Hovsgol drill core, HDP-04. Lake Hovsgol diatom biostratigraphy of the past 1 Ma includes 14 local diatom assemblage zones (LDAZ). Planktonic diatom flora of Lake Hovsgol is dominated by members of Stephanodiscus and Cyclotella. A large-scale shift from Stephanodiscus-dominated to Cyclotella-dominated flora occurred in the mid-Brunhes chron. Significant morphological variability of Cyclotella ocellata complex and Cyclotella cf. minuta, as well as the presence of new extinct endemic taxa of genus Stephanodiscus, suggest long speciation and/or adaptation history of diatom flora. The recognition of taxa morphologically similar to the extinct endemic species of Lake Baikal suggests potential correlation ties between Lake Hovsgol and Lake Baikal diatom biostratigraphies around the MIS 17, MIS 25, and, possibly, MIS 15 interglacial intervals. Narrow peaks of diatom abundance in the Lake Hovsgol sedimentary record are episodic and short-lived. These peaks may represent humid optima of past interglacials and/or interstadials, characterized by elevated surface runoff in the Hovsgol basin and relative highstands of the lake.     

The Preparation and Adsorption Properties of Novel Ternary Composited Diatomaceous Earth

Xianfeng large-scale lignite mining area, symbiotic diatomaceous earth mining area is the second largest diatomaceous earth mining in China with high organic matter content. The Xianfeng diatomaceous earth mining is a difficult development and utilization of low-grade diatomaceous earth, which has not been effective utilized due to low economic value of traditional processes. The objectives of this paper are utilizing high organic matter content diatomite as waste resources and improving the comprehensive utilization ratio of mineral resources in Xianfeng coal mining areas. The high organic content diatomaceous earth was purified by the acid washing and then calcinations under N2 as a protective atmosphere and high temperature of 500 to 800 ℃. The organic matter was carbonized with the formation of amorphous complex of activated carbon and diatomaceous earth. The novel ternary composited diatomaceous earth was prepared by combining carbonation diatomaceous earth and magnetic nanomaterials. The absorption property of ternary composited diatomaceous earth was improved through the organosilane and polyacrylamide modification to meet the needs of practical application. Electron microscopy showed that magnetic precursor calcined under N2 as a protective atmosphere, the surface of the magnetic nanoparticles were coated with amorphous carbon, which improved chemical stability and compatibility with diatomaceous earth. The magnetic nanoparticles and amorphous activated carbon uniformly dispersed in a diatomaceous earth surface and within the pores, to form a stable magnetic nanoparticles - the amorphous active carbon - ternary complexes. The specific surface area and methylene blue adsorption test showed ternary composited diatomaceous earth performing much higher than conventional diatomite products, the novel diatomaceous earth with specific surface area of 55.79 m2/g, methylene blue adsorption capacity of 44.5 m2/g. MgFe2O4 and Co3O4-based superparamagnetic ternary composited diatomaceous earth as an unique adsorbent has great application potential in organic pollutants and heavy metals pollution treatment of water. In addition, the CoFe2O4 based soft magnetic ternary composited diatomaceous earth has potential applications in magnetic plastics, rubber functional filler fields. This study shows that the proposed technology is conducive to a substantial increasing economic value of the Xianfeng diatomaceous earth mining, has a broad industrial application prospects.     

Sedimentation, depositional environment and diagenesis of Eocene biosiliceous deposits in Gafsa basin (southern Tunisia)

The sedimentary rocks of the Metlaoui Formation in the Gafsa basin (southern Tunisia), which may be grouped in three units: the basal (Thèlja), middle (Chouabine) and upper unit (Kef Eddour), provide a record of preserved sedimentary, authigenic and biological processes. This paper presents the findings of sedimentological investigations of the biosiliceous deposits of the middle unit. This unit contains either well-preserved (Opal-A) or diagenetically altered (Opal-CT, clinoptilolite, quartz and even clays) diatom frustules. Such diagenetic changes are commonly described in marine and lacustrine biosiliceous deposits. The fossil content of theses diatomaceous layers implies shallow-marine conditions.The opal-rich sediments, and the associated facies record the transgressive transitions associated with high organic productivity, probably enhanced by seasonal input of nutrients, and high sea level stands, and a close association with stratified water column conditions. The formation of bedded diatomaceous sediments is known to require either high organic productivity or anoxic conditions in bottom/intermediate water, and eventually both processes. The initial organic content of the biogenic deposits was impoverished in early stages of sedimentation and diagenesis. A large part of the organic matter could have been destroyed during early diagenetic processes and from further oxidation in outcrops.     

Miocene freshwater diatoms from the eastern slope of the submarine Ulleung Plateau (Krishtofovich Rise) in the Sea of Japan

The freshwater diatom flora from the tuffogenous sedimentary rocks of the submarine Ulleung Plateau of the southern Sea of Japan is studied and its complete taxonomic composition (96 species and varieties belonging to 33 genera) is revealed. It is characterized by species diversity and abundance of representatives of the freshwater genus Aulacoseira. The predominance of Aulacoseira is characteristic of the Miocene lacustrine deposits of the Sea of Japan and other regions, but the presence of ellipsoid species of narrow stratigraphic distribution allows the age of the recognized diatom flora to be limited to the Early Miocene. The species diversity and abundance of diatoms in the deposits of the Ulleung Plateau indicate the presence in the Early Miocene of a large freshwater lake in this region. Such lakes also existed on other large submarine rises of the Sea of Japan and its periphery before the onset of the tectonic activation which led to the descent of vast fragments of the continent and expansion of the Sea of Japan.     

The upper Miocene diatomaceous sediments of the northernmost Mediterranean region: A lamina-scale investigation of an overlooked palaeoceanographic archive

During the late Miocene the Mediterranean experienced a dramatic intensification of opaline accumulation, recorded by the deposition of diatomaceous sediments. The fine lamination of these deposits potentially records annual to sub-annual palaeoceanographic processes that occurred during a critical phase of the geodynamic evolution of the Mediterranean basin, which eventually led to the Messinian salinity crisis. The diatomaceous facies has been interpreted by previous researchers as the product of intensified upwelling currents and of bottom anoxia formation in the Mediterranean basin. However, until now, no efforts have been made to unravel the sedimentological and micropalaeontological content of these deposits at the lamina-scale. This paper presents the first case study of a systematic scanning electron microscope-based morphological investigation of the diatomaceous sediments deposited during the late Miocene at the northernmost offshoot of the Mediterranean basin (Piedmont Basin, north-west Italy). Using a non-invasive analytical approach, six faciological components (laminae, laminated packets, non-laminated intervals, burrows, opal-rich aggregates and mixed pelletal structures) and their relationships are described and interpreted herein. Following the lamina-scale study of these sediments, an annual sedimentary cycle could be identified and an accumulation rate (ca 50 cm kyr⁻¹) inferred that is atypical for a setting actively influenced by upwelling. The role played by the entanglement of diatom valves in creating a physical barrier to the bioturbation is here emphasized as the main process responsible for the preservation of the laminated fabric of diatomaceous sediments, challenging the supposed role of deep anoxia. These results suggest that the late Miocene diatomaceous deposition in the Piedmont Basin cannot be univocally considered as a by-product of upwelling intensification and seafloor oxygen depletion.     

湖泊硅藻氧同位素:一种前景广阔的陆相古气候指标

硅藻氧同位素已日益成为陆相古气候重建的一种重要手段。文章在简述这一领域已取得的基本认识基础上,着重介绍了近年来的重要进展。主要进展包括: 1)在硅藻的分离纯化方面,规范了重液分离法和新的重力差异流体分离法;2)完善了分步氟化法,创生了高温碳还原法的氧同位素制取技术;3)通过实验培养和天然湖泊监测实验,证实了硅藻氧同位素与温度的分馏平衡关系;4)湖泊硅藻氧同位素可以反映古温度、气候干旱事件和大气降水来源变化。同时,对目前硅藻氧同位素在湖泊沉积古气候研究中存在的主要问题作了讨论和展望。