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中国特马豆克阶笔石地层述评 总被引：7，自引：1，他引：6
特马豆克阶是奥陶系第一个顶底界均已确立全球界线层型的年代地层单元,由于这两个GSSP都不在我国,因此如何在我国各个地区准确识别这两条界线,了解阶内的笔石和牙形刺序列,对我国奥陶纪地层和古生物研究具有重要意义。简要介绍特马豆克阶和奥陶系底界全球层型的纽芬兰GreenPoint剖面及特马豆克阶顶界全球层型的瑞典Diabasbrottet剖面,对界线附近的生物地层进行了分析讨论,并对GSSP的确立过程作了简要回顾。在以往大量成果积累及近年来工作的基础上,对我国特马豆克阶的笔石序列提出了新的观点:根据对吉林大阳岔等剖面的最新研究,华北板块的特马豆克阶笔石地层从下至上可以识别出4个笔石带——Rhabdinoporaflabelliformisparabola带、Anisograptusmatanensis带、Psigraptusjacksoni带和Aorograptusvictoriae带,弃用以往长期使用的Adelograptus-Clonograptus带;同时提出华南的特马豆克阶从下到上可以识别出7个笔石带——Rhabdinopora?taojiangensis带,R.flabelliformisparabola带,Anisograptusmatanensis带,R.flabelliformisanglica带,Aorograptusvictoriae带,Acanthograptussinensis带,Hunnegraptuscopiosus带。对采自四川古蔺纳羊箐桐梓组顶部笔石标本的研究表明,该层位相当于特马豆克期末的Hunnegraptuscopiosus带。此外还将我国的特马豆克阶笔石序列与国外若干主要地区进行了对比。 相似文献
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全球下奥陶统-中奥陶统界线层型候选剖面——宜昌黄花场剖面研究新进展 总被引：1，自引：0，他引：1
湖北宜昌黄花场剖面是我国奥陶系大湾阶的界线层型剖面，高精度生物地层以及岩石、层序地层和碳同位素地球化学的综合研究表明，该剖面完全符合关于建立全球下奥陶统一中奥陶统界线（即奥陶系第三个尚待正式命名的阶）界线层型剖面和点位（GSSP）的条件。建议以该剖面牙形石Baltoniodus？triangularis的首现层位，作为划分全球下奥陶统一中奥陶统界线的GSSP。所建议的GSSP交通方便，位于距宜昌市北北东22km的公路旁，地层出露完美无缺，界线生物层位于大湾组下段SHod-16层底部，距大湾组底部10．57m；界线上下发育了B．？triangularis的完整演化序列，并伴生有极好的Baltoniodus、Trapezognathus、Periodon和Microzarkodina等牙形石属种演化序列来作为佐证；界线之上0．2m所出现的世界广布的Microzarkodina abellum可作为划分此界线的辅助标志。界线生物层位于低位海侵序列之中，界线之下0．6m处所显示的从高位到低位的层序转换面和碳同位素最大偏移，与全球此时所发生低位事件密切相关，可作为识别该界线的物理和化学标志。所建议的界线生物层与笔石Azygograptus suecicus生物带上下组合之间的界线接近，与几丁虫Belonechitina cf．henryi生物带底界几乎一致，因此，所建议的界线易于在全球，无论浅水碳酸盐相、还是深水笔石相，识别和进行精确对比。同样的生物组合序列和层序及碳同位素异常亦在黄花场剖面之北5km的陈家河（即大坪）剖面得到了验证． 相似文献
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Suryendu Dutta Michael Steiner Santanu Banerjee Bernd-Dietrich Erdtmann Silambuchelvan Jeevankumar Ulrich Mann 《Journal of Earth System Science》2006,115(1):99-112
Chuaria circularis (Walcott 1899) from the Suket Shale of the Vindhyan Supergroup (central India) has been reinvestigated for its morphology
and chemical composition using biostatistics, electron microscopy and pyrolysis-gas chromatography. Morphology and microscopic
investigations provide little clues on the specific biological affinity ofChuaria as numerous preservational artifacts seem to be incorporated. On the contrary, the predominance of η aliphatic pyrolysates
of presently studiedChuaria from India rather supports an algal affinity. Moreover, the reflectance ofC circularis can be used to obtain a comparative maturity parameter of the Precambrian sediments. The review of the age and geographical
distribution ofC circularis constrains that this species cannot be considered as an index fossil for the Proterozoic time. 相似文献
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A proposed GSSP for the base of the Middle Ordovician Series： the Huanghuachang section,Yichang, China 总被引：2，自引：0，他引：2
XiaofengWang SvendStouge Bernd-D.Erdtmann XiaohongChen ZhihongLi ChuanshangWang QingluanZeng ZhiqiangZhou HuimingChen 《《幕》》2005,28(2):105-117
The Huanghuachang section near Yichang, southern China meets the requirements of Global Stratotype Section and Point (GSSP) for the base of the Middle Ordovician Series and the yet-to-be-named third stage of the Ordovician System (or lower stage of Middle Ordovician Series). The conodont succession at the section is complete across the Lower to Middle Ordovician series boundary and several excellent phylogenetic lineages of Baltoniodus, Trapezognathus, Periodon, and Microzarkodina are represented. The definition of the base of the Middle Ordovician is proposed to be the first appearance datum (FAD) of Baltoniodus? triangularis in the section. It is followed closely by the FAD of Microzarkodina flabellum, which is taken as a reasonable proxy for the boundary. This level approximates the boundary between the lower and upper intervals of the Azygograptus suecicus graptolite Biozone, and nearly coincides with the base of the Belonechitina henryi chitinozoan Biozone.The proposed GSSP for the base of the international Middle Ordovician Series is located in a roadside exposure at the base of Bed (SHod) 16, 10.57 m above the base of the Dawan Formation in the measured Huanghuachang section near Yichang City, southern China. The same faunal succession is also recorded from the Chenjiahe (formerly Daping) section, 5 km to the north of the Huanghuachang section. The proposed boundary horizon can be recognized and correlated globally with high precision in both relatively shallow-water carbonate facies as well as in deep-water graptolite facies. 相似文献
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上扬子区早古生代全岩Ce异常与海平面长缓变化 总被引：15，自引：2，他引：13
65个全岩稀土样品采自湖北省宜昌地区下寒武统至下志留统的经典剖面 .样品测试由单通道扫描等离子光谱仪 (ICP AES)完成 .REE含量依北美页岩组合(NASC)标准化 ,并按log[3Cen/ ( 2Lan Ndn) ]计算Ce异常值 .以全岩Ce异常作为海平面变化的定量指标 ,识别出 5个明显的海平面升降旋回 ,发现多幕次黑色岩系与海侵事件严格对应 .鉴于同期黑色岩系的全球性分布和华南特定的古地理格局 ,提出华南早古生代多幕次黑色岩系的最小含氧层扩展成因模式 . 相似文献
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The southern Bida Basin in central Nigeria forms a part of the larger Bida or Middle Niger Basin, which is contiguous with the south east trending (petroliferous) Anambra Basin. These basins were major depocenters for Campanian–Maastrichtian sediments in southern and central Nigeria prior to the build up of the Tertiary Niger delta. The successions in the southern Bida Basin consist of the basal Lokoja Formation, overlain by the Patti Formation and capped by the Agbaja Formation. The Lokoja Formation is a sequence of matrix supported conglomerates and sandstones overlying the Pre-Cambrian to Lower Paleozoic basement. Depositional environments are predominantly within fluvial systems of a continental setting. The Patti Formation consists of dark grey carbonaceous shales; mudstone and siltstones representing flood plains to shallow marine deposits with likely organic rich intervals. The overlying Agbaja Formation is made up of ferruginised oolitic and kaolinitic mudstone of a marginal marine environment. Twenty samples of shales of the Patti Formation were studied by incident light microscopy and geochemical analysis to determine the maceral components, geochemical type and potential yield of the pyrolysate. Maceral analysis indicate a large abundance of vitrinite (50–85%; mean = 66%); moderate abundance of liptinites (10–33%; mean = 18%) and lesser amounts of inertinite (9–40%; mean = 16%). Total organic carbon (TOC) values vary from 0.17 to 3.8 wt.% (mean = 2.1 wt.%) with most samples having greater than 2 wt.% TOC. Three of the samples yield greater than 2 kg(HC)/ton of rock suggesting a fair source rock potential. Most of the samples are thermally immature to marginally mature with vitrinite reflectance ranging from 0.4 to 0.6% Rom and Tmax values of 407–426 °C. Given the prevalence of the humic Type III kerogen, maturity and hydrocarbon potential yields, we conclude that the Patti Formation source rock facies have moderate to fair potential for gaseous hydrocarbons which have not yet been generated at the present day outcrop levels but could be important gas source where buried down-dip. 相似文献
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Early Paleozoic whole-rock Ce anomalies and secular eustatic changes in the Upper Yangtze region 总被引：1，自引：1，他引：0
The 65 whole-rock REE samples studied come from the classic sections of Early Cambrian to Early Silurian in the Yichang area, Hubei Province. REE concentrations tested on ICP-AES are normalized to the North American Shale Composite (NASC), and Ce anomaly values are calculated based on log[ 3Cen/(2Lan+Ndn)] . With the whole-rock Ce anomaly used as a quantitative index of sea-level changes, 5 prominent eustatic circles are recognized, and a good corresponding relationship is observed between the black shale episodes and the transgressive events. On account of the global distributions of coeval black shales and the specified paleogeographic background of South China, a genetic hypothesis based on the model of O2-minimum zone expansion is suggested for the Early Paleozoic multi-episode black shales in South China. 相似文献
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Bernd-D. ERDTMANN 《中国科学D辑(英文版)》2009,52(3):287-299
The Tremadocian is the first stage of the Ordovician System and is subdivided into two parts in general. The Upper Tremadocian,
spanning a temporal interval of ca. 8 Ma, yields graptolite faunas crucial for biostratigraphic division and correlation in
high resolution. Relatively complete successions of Upper Tremadoc graptolite zones have been proposed in Scandinavia, and
North and South America. In South China, the coeval graptolite strata are widespread in deep water facies, but the successions
of graptolite zones recognized so far are quite incomplete and thus very difficult to be correlated with those in other countries.
In recent years, we have sampled bed by bed the Nanba section in the Yiyang area, Hunan Province and, below the Tetragraptus approximatus Zone, identified four Upper Tremadoc graptolite zones in descending order: the Hunnegraptus copiosus Zone, the Araneograptus murrayi Zone, the Aorograptus victoriae Zone and the Adelograptus tenellus Zone. To date, the Nanba section is the only section in China that presents a relatively complete and globally comparable
succession of Upper Tremadoc graptolite zones. Therefore, this study not only confirms the existence of some Upper Tremadoc
graptolite zones that were never found before in China, but also facilitates a highly resolved division and correlation for
the Upper Tremadoc graptolite strata in China.
Supported by National Natural Science Foundation of China (Grant No. 40472014) 相似文献
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