Sequences and biofacies packages in the mid‐Cenozoic Gambier Limestone,South Australia: Reappraisal of foraminiferal evidence     

Q. Li  B. McGowran  M. R. White 《Australian Journal of Earth Sciences》2013,60(6):955-970

The mid to outer neritic carbonates of the Gambier Limestone (Upper Eocene to lower Middle Miocene) can be divided into seven units by using criteria of sequence stratigraphy and foraminiferal biofacies. The boundaries fall mainly on erosional surfaces, even though the temporal duration of these surfaces appears to be largely beyond the resolution of foraminiferal biostratigraphy. The Eocene/Oligocene contact is distinctively unconformable in several sections, with at least part of the Upper Eocene sediments missing. Chert nodules, common to abundant in most sections, are associated with deep‐ or cool‐water benthic assemblages (> 100–200 m and <15°C), indicating cool, nutrient‐rich bottom conditions probably influenced by the Antarctic Circumpolar Current beginning during the Early Oligocene. The mid‐Oligocene fall in sea‐level was probably coupled with a major local uplift that removed at least part of the Lower Oligocene, an event widely recorded in the Australian‐New Zealand region. In areas weakly affected, this glacioeustatic lowstand is represented by chert‐free limestone and grey to pink dolomites in some sections, with a poorly preserved assemblage comprising few planktonic and deep‐water benthic species. Local unconformities separate regional unconformity‐bounded or allostratigraphic packages of strata to represent third‐order sequences. Although variations in local subsidence might have influenced accumulation space and sediment thickness, glacioeustatic influence on the packaging of the sequences and units of the Gambier Limestone was easily the more effective and concordant with the global patterns.  相似文献   

Vines 1 revisited: are older Neoproterozoic glacial deposits preserved in Western Australia?     

P. W. Haines  R. M. Hocking  K. Grey  M. K. Stevens 《Australian Journal of Earth Sciences》2013,60(3):397-406

The stratigraphy in Vines 1, a 2017.5 m-deep cored stratigraphic hole drilled by the Geological Survey of Western Australia in 2001 near the Western Australian – South Australian border, has been reinterpreted with implications for the Neoproterozoic to Cambrian geological history of the Officer Basin. A previous interpretation considered the intersected succession as a conformable stratigraphic package, the Vines Formation. An assemblage of palynomorphs, found throughout the hole and previously used to infer an age of no older than earliest Cambrian, is now thought to consist of contaminants. An older assemblage, which is considered to be reworked and inherited from underlying rocks, provides a new maximum age constraint of mid-Neoproterozoic. Based on sedimentological interpretations and comparisons with other drillholes in the western Officer Basin, and the succession in the eastern Officer Basin, the Vines 1 succession is reinterpreted as four discrete sedimentary packages, the Pirrilyungka (new name), Wahlgu, Lungkarta and Vines (redefined) Formations, in ascending order. The Pirrilyungka and Wahlgu Formations include glacigenic sediments and may correlate with similar glacial successions in Supersequences 2 and 3 (mid to late Cryogenian) of the Centralian Superbasin, and the Sturt Tillite and Elatina Formation and their equivalents in the Adelaide Rift Complex of South Australia, respectively. The eolian Lungkarta Formation and fluvial Vines Formation are considered, on regional evidence, to be most likely of Ediacaran to earliest Cambrian age.  相似文献   

辽西—冀北地区土城子组的地质时代、年龄及其国际地层对比   总被引：3，自引：1，他引：2  

王思恩  高林志  万晓樵  宋彪 《地质通报》2013,32(11):1673-1690

辽西—冀北地区土城子组(后城组)含有各类化石,包括植物、孢粉、介形类、叶肢介、昆虫及恐龙类等,各门类化石都对土城子组的时代提出归属与生物演化依据。通过与国内外相关生物群(组合)的研究与对比,尤其是孢粉、介形类微体化石大区域的国际对比,将土城子组的地质时代划归为晚侏罗世早—中期(Oxfordian-Kimmeridgian)。土城子组的地磁年代学研究,也得出大致相同的时代结论。笔者在辽西金岭寺—羊山盆地土城子组剖面中,采用SHRIMP锆石U-Th-Pb同位测定技术,对凝灰岩中的锆石进行了年龄测定,获得的206Pb/238U年龄为:第22层140.2Ma±1.3Ma(N=13,13个数据加权平均值);第30层139.6Ma±1.9Ma(N=12);小刘家沟剖面土城子组上部凝灰岩139.6Ma±0.7Ma(N=11);第83层137.3Ma±1.0Ma(N=13)。由于第22层距土城子组底界369m,据沉积速率推算约为1.5Ma。因此,土城子组底界年龄应为141.7Ma±1.3Ma。第83层接近土城子组顶界,137.3Ma±1.0Ma年龄值可大致视为土城子组顶界的年龄。如此推断,上侏罗统牛津阶(Oxfordian)底界年龄应接近141.7Ma±1.3Ma,基默里奇阶(Kimmeridgian)上界年龄应为137.3Ma±1.0Ma左右,而国际地质年表中推导、标注的两者年龄分别为163.5Ma±1.0Ma和152.1Ma±0.9Ma,与笔者实测的年龄值分别相差21Ma和15Ma,对此进行了深入的探讨。  相似文献   

Middle Permian radiolarians from Anmenkou, Chaohu, Northeastern Yangtze platform, China     

Masao  Kametaka  Hiromi  Nagai  Sizhao  Zhu  Masamichi  Takebe 《Island Arc》2009,18(1):108-125

The biostratigraphy of the Middle Permian Gufeng Formation in the northeastern Yangtze platform is examined based on radiolarians. This study is concentrated on the Anmenkou section in the Chaohu area of Anhui Province, China. The Gufeng Formation is divided into the Phosphate Nodule-bearing Mudstone Member (PNMM) and the Siliceous Rock Member (SRM) in ascending order. The former primarily consists of mudstone including abundant phosphate nodules, and the latter consists mainly of alternating beds of chert, siliceous mudstone and mudstone, with intercalations of porous chert. Ammonoids in the mudstone of the lower PNMM are Wordian. Chert, siliceous mudstone and mudstone of the SRM include abundant radiolarians with sponge spicule assemblages suggestive of the Wordian–Capitanian. Albaillellaria are predominant in the lower SRM, while Entactinaria and Spumellaria are predominant in the middle and upper SRM. These radiolarians correspond to three radiolarian assemblage zones: Pseudoalbaillella longtanensis – Pseudoalbaillella fusiformis , Follicucullus monacanthus , and Follicucullus scholasticus – Ruzhencevispongus uralicus . The assemblage of radiolarians and sponge spicule fauna suggests a depositional depth of 150–500 m. The radiolarian fauna of the Gufeng Formation is considered to be representative of the relatively shallow, tropical radiolarian fauna of the Middle Permian eastern Paleotethys.  相似文献   

山东张夏期(中寒武世晚期)三叶虫生物地层   总被引：7，自引：3，他引：4  

袁金良  李越  穆西南 《地层学杂志》2000,24(2):136-143,T001

根据山东长清张夏虎头山至黄草顶、淄博市淄川区峨庄乡黑石寨谢家峪及新泰县九龙村九龙山的中寒武世晚期地层剖面的新材料 ,分析了山东张夏期三叶虫的地层分布 ,讨论了张夏组的顶底界线 ,扼要地比较了张夏期的 6个多节类三叶虫带与华南过渡区的 4个球接子带。  相似文献   

中太平洋海山区富钴结壳的钙质超微化石地层学研究   总被引：14，自引：1，他引：13  

苏新马维林  程振波 《地球科学》2004,29(2):141-147

对“大洋一号”调查船在中太平洋采集的N1-15和N5E-06 2个富钴结壳样品进行了钙质超微化石及其生物地层学的研究与分析.这2个结壳从结构上分为3层: 致密型上层、疏松型中层和致密型下层.在研究中对各结构层和各层中有颜色或细微结构变化的层位都进行了详细的取样和分析.在识别了12个新生代钙质超微化石事件的基础上, 确定了2个结壳致密型上层结壳都为晚更新世以来的沉积, 它们的疏松型中层结壳为上新世到中更新世的沉积.对N5E-06富钴结壳来说, 其致密型下层结壳下部形成于中晚古新世到早渐新世的59.7~ 32.8 Ma期间.N1-15富钴结壳致密型下层的形成时代目前暂时定为中新世.研究注意到在2个结壳中都没有发现可信的晚渐新世到中新世的化石记录, 在个别层位之间存在着沉积间断.   相似文献   

Application of radiolarians and other fossils in non-Smith strata--Exemplified by the A'nyêmaqên melange belt in East Kunlun Mts     

ZHANG Kexin  HUANG Jichun  YIN Hongfu  WANG Guocan  WANG Yongbiao  FENG Qinglai  TIAN Jun 《中国科学D辑(英文版)》2000,43(4)

The main character of melange strata in an orogenic belt is the integration of mixed materials due to the superposition, displacement or loss of various tectonic slices (blocks) of different origins and environments, different scales, different grades of deformation and metamorphism, and different stages of tectonic evolution. The approach to non-Smith strata in an orogenic belt is to focus on the understanding of the age, facies, tectonic setting of the original formation and the process of deformation-metamorphism of each tectonic slice, reconstruct the history of dispersal and integration of these tectonic slices in time and space, i.e. 4-dimensional. This paper studies the age and facies of the original formation of tectonic slices in the A'nyêmaqên melange belt based on new data of radiolarians, sporo-pollen and trace fossils, and cast new lights on the research of the evolution process of that belt.  相似文献   

藏南吉隆地区二叠纪生物地层     

朱才伐  田立富  孙黎明  张振利 《地层学杂志》2008,32(3)

藏南吉隆地区二叠系主要为一套中厚层状碳酸盐岩、石英砂岩夹泥质岩岩性组合,产丰富的腕足类、珊瑚、苔藓虫、菊石及海百合茎、遗迹化石等多门类化石,包括5个腕足动物组合、1个菊石带、2个珊瑚组合、1个海百合化石层、1个遗迹化石层。根据岩性二叠系划分为基龙组和曲布日嘎组。基龙组时代相当于早二叠世阿丁斯克期—萨克马尔期。曲布日嘎组时代以栖霞期—茅口期为主,顶部可能包括部分吴家坪期。  相似文献   

The upper Volgian Substage in Northeast Siberia (Nordvik Peninsula) and its Panboreal correlation based on ammonites   总被引：1，自引：0，他引：1  

V. A. Zakharov  M. A. Rogov 《Stratigraphy and Geological Correlation》2008,16(4):423-436

Section of the middle and upper Volgian substages and basal Boreal Berriasian in the Cape Urdyuk-Khaya (Nordvik Peninsula) is largely composed of dark argillites substantially enriched in C_org. Characteristic of the section is a continuous succession of ammonite, foraminiferal, ostracode, and dinocyst zones known also in the other Arctic areas. Boundaries of the upper Volgian Substage are recognizable only based on biostratigraphic criteria. The succession of the middle Volgian Taimyrosphinctes excentricus to basal Ryazanian Hectoroceras kochi zones is characterized. The range of the substage is revised. The lower Exoticus Zone, where ammonites characteristic of the Nikitini Zone upper part in the East European platform have been found, is referred to the middle Volgian Substage. Newly found ammonites are figured. Two possible positions of the Jurassic-Cretaceous boundary in the Arctic region, i.e., at the lower and upper boundaries of the Chetae Zone at the top of the upper Volgian Substage, are discussed.  相似文献   

辽东半岛早及中寒武世早期生物地层     

郭鸿俊  昝淑芹 《吉林大学学报(地球科学版)》1991,(1)

辽东半岛寒武系发育良好,化石丰富,是研究寒武纪地层和三叶虫动物群的理想地区。笔者将下寒武统及中寒武统毛庄阶划分了7个生物带,其中新建立生物带1个,新划分出生物带2个,并与国内外有关地区进行对比。三叶虫动物群包括34个种,分属19个属和3个亚属。由于篇幅所限,本文只简要描述了带化石,新属、新种另文发表。  相似文献