Integrated Radiolarian and Conodont Biostratigraphy of the Middle to Late Permian Linghao Formation in Northwestern Guangxi, South China

The Permian radiolarian zones and their correlations with conodont zones or other chronostratigraphic schemes are still under debate. In this study, four genera, 21 species and two subspecies of radiolarians together with one genus and six species of conodonts were recovered from the Linghao Formation cropping out at the Longwangpo (LWP) section, northwestern Guangxi, South China. Six radiolarian interval zones and one abundance zone are recognized in the section, namely in ascending order, the Follicucullus scholasticus, Albaillella cavitata, A. protolevis, A. levis, A. excelsa, A. triangularis Interval zones and A. yaoi Abundance Zone. They are correlated with the Clarkina dukouensis, C. guangyuanensis and C. orientalis conodont zones recognized at the same section. Based on our data, the F. scholasticus Interval Zone and the lowermost part of A. cavitata Interval Zone are recognized to be upper Capitanian age, whereas the four Albaillella Interval zones are of Lopingian age (Wuchiapingian to the late Changhsingian). Two previously known Changhsingian radiolarian zones, namely the A. triangularis and A. yaoi Interval zones, should be extended down to the uppermost Wuchiapingian in this studied section.     

滇西保山熊洞村栗柴坝组牙形石的发现及其地质意义

针对保山地层区熊洞剖面原属栗柴坝组的灰岩进行了牙形石样品分析,总计建立了5个牙形石带,分别为Pterospathodus pennatus procerus带、Kockelella walliseri带、Ancoradella ploeckensis带、Polygnathoides siluricus带和Polygnathus nothoperbonus带。该剖面第8层原属栗柴坝组,Polygnathus nothoperbonus分子的出现证实其为下泥盆统埃姆斯阶的地层,应归为向阳寺组。剖面总体对应志留系温洛克统底部到下泥盆统埃姆斯阶中部,中间缺失志留系罗德洛统卢德福特阶—下泥盆统埃姆斯阶之间的8～10个标准牙形石带,说明该地区后期可能受构造作用影响,志留系和泥盆系界线为断层接触。该剖面牙形石序列的建立一定程度上完善了滇西保山地层区志留系生物地层的研究程度,为下一步该区生物地层格架的建立奠定了基础。     

Conodont Biostratigraphy of the Middle Cambrian through Lowermost Ordovician in Hunan, South China

Since 1985, samples with a total weight of more than 14,000 kg, mainly from three key sections in western and northwestern Hunan, South China, have been processed for conodonts. In strata older than the late Late Cambrian paraconodonts have proved useful for stratigraphic subdivision and correlation. Thirteen conodont zones are proposed in the Middle Cambrian through lowermost Ordovician. The correlation between these zones and those of North China, western U. S.A., western Newfoundland, Canada, and Iran is discussed. In ascending order, these 13 zones are as follows: The Gapparodus bisulcatus-Westergaardodina brevidens Zone, Shandongodus priscus-Hunanognathus tricuspidatus Zone, Westergaardodina quadrata Zone, Westergaardodina matsushitai-W. grandidens Zone, Westergaardodina lui-W. am Zone, Westergaardodina cf. calix-Prooneotodus rotundatus Zone, Proconodontus tenuiserratus Zone, Proconodontus Zone, Eoconodontus Zone, Cordylodus proavus Zone, Cordylodus intermedius Zone, Cordylodus lindstromi Zone, and     

西藏泥盆纪海相红层的分布与时代

在作者及前人对西藏地区泥盆纪地层学、古生物学等资料研究的基础上,作者对该区泥盆纪海相红层进行了初步的系统整理。共识别出6层(套)海相红层,它们是:早泥盆世扎西岗组海相红层(洛赫柯夫阶—布拉格阶)(XDRB1)和春节桥组上部海相红层(埃姆斯阶)(XDRB2),中泥盆世海通组海相红层(艾费尔阶)(XDRB3)和丁宗隆组底部海相红层(吉维阶)(XDRB4),晚泥盆世查果罗玛组(下部)海相红层(弗拉斯阶)(XDRB5)和羌格组顶部海相红层(法门阶)(XDRB6)。所有海相红层均形成于近岸或浅水碳酸盐岩台地环境,因此,属于浅水-半深水陆棚红层,此外,还讨论了中国南方泥盆纪海相红层的分布及全球法门期海相红层广布事件。     

浙江省船山组的划分与对比

桐庐沈村船山组深灰色灰岩 ,厚 12 6 .35 m ,与下伏地层黄龙组、上覆地层梁山组均为整合关系。船山组可划分为 3个化石带 ,上部为 Eoparafusulina pseudosimplex带 ,归属隆林阶 ;中部为 Sphaeroschwagerina subrotunda带 ,归属紫松阶 ;下部为 Triticites subcrassulus带 ,归属逍遥阶。     

贵州关岭三叠系竹杆坡组、小凹组头足类化石——兼论关岭生物群的时代

贵州关岭地区中、上三叠统竹杆坡组和小凹组产较丰富的头足类化石，计有11科19届37种，其中Enoploceras,Alloceratites,Sibyllites等属以及Trachyceras aon种系国内首次报道。自下而上可识别出(1)Xenopratrachyceras primum带；(2)Protrachyceras deprati带；(3)Protrachyceras costulatum带；(4)Trachycems multituberculatum带；(5)Sirenites cf. senticosus带等5个菊石带。讨论了每个菊石带的特征，并与国外同期菊石带进行了对比，指出(1)带与欧洲拉丁期早期R.reitzi带相当，(2)和(3)带分别与拉丁期晚期E.curionii带和P.archelaus带相当，(4)和(5)带分别与欧洲早卡尼期早期T.aon带和北美的早卡尼期晚期Sirenites nanseni带对比。关岭生物群产出层位与Trachyceras multituberculatum菊石带层位一致，时代应为早卡尼期早期。     

南京地区岩关早期地层——茨山组

<正> 南京地区的下石炭统,按其岩性及生物群特征,自下而上分为茨山组、金陵组、高骊山组、和州组及老虎洞组五个地层单位。茨山组为本文创立,该组包括原划为上泥盆统五通组擂鼓台段上部的一套碎屑岩和金陵组底部含腕足类化石的砂岩。关于五通组的时代,潘江(1953)在南京龙潭的五通组(当时称五通系)上部发现繁盛于泥盆纪的胴甲鱼类(Antiarchi)。根据鱼化石的特征,刘东生、潘江(1958)认为五通组的时代是晚泥盆世早期或中泥盆世晚期。罗兴、潘鹏(1959)在南京龙潭相当含胴甲鱼的层位中,采到了具晚泥盆世特征的斜方薄皮木(Leptophloeum rhombicum Dawson)植物。李星学(1963)根据上述鱼     

大巴山西段寒武纪的三叶虫分带

<正> 本文的大巴山西段,包括宁强、勉县、南郑、城固及西乡等地区,寒武纪地层发育良好,从上到下包括中寒武统陡坡寺组(小关子组),下寒武统孔明洞组、阎王碥组、仙女洞组、郭家坝组及相当于梅树村阶的地层。化石非常丰富,包括三叶虫、腕足类、古杯、高肌虫,海绵及小亮化石等,其中以三叶虫属种和数量最多,除相当梅树村阶的地层和筇竹寺组下部     

Turonian Radiolarians in the Section of Ak Mountain,Crimea

In the sections from the western and eastern peaks of Ak Mountain, the Patellula selbukhraensis Zone (upper part of the lower Turonian), which is established for the first time in the southwestern Mountainous Crimea, is traced. The first data on the radiolarian distribution in the section of the eastern peak of Ak Mountain, which is stratotypical of the Phaseliforma turovi (middle Turonian, without the upper part) and Actinomma (?) belbekense (upper part of the middle Turonian–upper Turonian) zones, are presented. These zones are also traced in the parallel section of the western peak of Ak Mountain.     

安徽淮北地区寒武系“崮山阶”—凤山阶新知

根据三叶虫Acanthometopus obesus、Trianguraspis nodus、Petalocephalus laevis、Taishaniasp.等的发现,将淮北地区捻山剖面原属凤山阶的地层划归长山阶,以Acanthometopus带作为该区长山阶最顶部的三叶虫带,淮北地区凤山阶与长山阶的界线应在Ptychaspis-Tsinania带与Acanthometopus带之间;通过与标准剖面及邻近地区的对比,淮北地区的崮山组应予解体,原崮山组上部与炒米店组岩性一致,应划入炒米店组,其下部岩性与张夏组一致,应划入张夏组,淮北地区无崮山组。淮北地区的炒米店组跨越了整个长山阶和凤山阶中下部,据岩性差异可分为上、下两段;炒米店组在华北地区具有明显的穿时性,其底界从长山阶底界跨至凤山阶顶界。     

浙江桐庐县刘家奥陶纪剖面生物地层学初步研究

新发现的浙江桐庐刘家剖面位于马金一乌镇断裂与球川一萧山断裂之间,是浙西北地区以碎屑岩沉积为主的代表性奥陶纪地层剖面。根据所获得的宁国组和胡乐组的笔石化石,初步建立了该层段的笔石生物地层序列,自下而上包括Tetragraptusapproximatus带、Corymbograptusdeflexus带、Azygograp...     

广西六景泥盆纪吉维阶-弗拉斯阶界线层牙形石生物地层

广西六景泥盆系剖面是我国泥盆系标准剖面之一 ,通过对其吉维阶 -弗拉斯阶界线上下地层进行详细的牙形石生物地层研究 ,自上而下识别出 12个牙形石带 :Palmatolepis jamieae带、Palmatolepis hassi带、Palmatolepispunctata带、Palmatolepistransitans带、上 Mesotaxisfalsiovalis带、下 Mesotaxisfalsiovalis带、Klapperina dispar-ilis带、上 Schmidtognathus hermanni- Polygnathus cristatus带、下 Schmidtognathus hermanni- Polygnathus cristatus带、上 Polygnathus varcus带、中 Polygnathus varcus带、下 Polygnathus varcus带。吉维阶 -弗拉斯阶界线 (即中 -上泥盆统界线 )由 Ancyrodella binodosa→ Ancyrodella rotundiloba early form→ Ancyrodella rotundiloba late form这一演化线系中的 Ancyrodella rotundiloba early form的首次出现确定 ,处于下 Mesotaxis falsiovalis带下部 ,在谷闭组底界之上 1.80 m处。     

Micropaleontological data (dinocysts,nannoplankton, spores and pollen) and biostratigraphy of the Alkun Formation,North Ossetia

The initially obtained data characterize organic-walled phytoplankton (dinocysts), nannoplankton, spores, and pollen from the Upper Argun, Alkun, and Lower Assa deposits of the Fiagdon and Mairamadag sections situated on the southeast of North Ossetia (North Caucasus) in the Alkun Formation stratotype area. The lithology of the formation is described, and its position in the Oligocene-Miocene succession is considered. According to the analyzed data on organic-walled phytoplankton from the Fiagdon and Mairamadag sections, the transitional late Oligocene-early Miocene dinoflora from the top of the Argun Formation and the lower part of the Alkun Formation is in general of the Miocene aspect. Based on the dinocysts, deposits from the upper part of the Alkun Formation coupled with the Assa Formation are attributed to the lower Miocene. The entire interval of the studied deposits corresponds to the acme subzone Def of the Ebu Zone in the Mediterranean dinocyst zonation by D. Zevenboom, where it spans the top of the Chattian and lower part of the Aquitanian Stage. Nannoplankton assemblages from the Alkun deposits are tentatively correlated with the nannoplankton assemblage of Zone NN1 in the standard zonation by E. Martini. It is impossible to date precisely the Alkun Formation based on nannoplankton, as the respective deposits are lacking index species and characteristic taxa of the standard zonation. The dominance of the cosmopolitan species Cyclicargolithus floridanus is a peculiar feature of nannoplankton assemblages from the Alkun Formation. Palynological data are used to consider the dynamics of the evolution of the vegetation cover and climate. Four episodes of relative cooling are distinguished against a background of warm-temperate climatic conditions in general. The most significant episodes occurred in the mid-Alkun time and during the early phase of the Assa time.     

Planktonic foraminiferal biostratigraphy of the Upper Barremian and Aptian of Crimea

Reexamination of the Barremian–Aptian planktonic foraminifers from three sections (Verkhoirechie, mountain Krasnaya, and Marino) allowed the biostratigraphic scheme for Southwest and Central Crimea to be refined and updated. The following standard zones are recognized in the studied sections: Blowiella blowi (upper Barremian), Hedbergella excelsa (upper Barremian–lower Aptian), Leupoldina cabri (lower Aptian), H. luterbacheri, Globigerinelloides ferreolensis, Gl. barri, Gl. algerianus, Hedbergella trocoidea, Paraticinella rohri (upper Aptian). Beds with Hedbergella ruka are recognized in the B. blowi Zone. Foraminifers from the Partizanskoe section, representing the lower Aptian L. cabri and H. luterbacheri zones, are studied. The recognized strata are correlated with ammonite and nannoplankton zones and paleomagnetic data.     

广西六景泥盆系弗拉斯阶-法门阶界线层牙形石生物地层及碳同位素组成

广西六景泥盆系剖面是中国泥盆系标准剖面之一,通过对其弗拉斯阶-法门阶(F-F)界线附近地层进行详细的牙形石生物地层研究,自下而上识别出3个牙形石带:晚rhenana带、linguiformis带和triangularis带。F-F界线位于融县组下部(第7号层与第8号层之间),在谷闭组顶界之上3.32,m处。碳同位素的分析结果表明,F-F之交δ13C具有显著正偏移,增幅为2.0‰,与湖南老江冲、广西垌村和杨堤以及欧洲、美洲、非洲和澳洲等地的F-F界线附近的碳同位素记录一致,且具有相近的变化幅度。δ13C正异常与F-F界线上的生物灭绝有关,由于食微生物的高等生物灭绝,微生物大量繁盛,诱导海水缺氧,导致海洋有机碳埋藏速率增加,从而形成δ13C的正偏。F-F界线层发育一套以碎屑灰岩为特色的事件沉积,该事件沉积在广西乃至全球具有等时性,可能与小行星碰撞地球引起的全球性海啸有关。     

Planktonic foraminiferal biostratigraphy of the Coniacian-Maastrichtian sequences of the Bey Dağları Autochthon,western Taurides,Turkey: thin-section zonation

Planktonic foraminifer distributions in seventeen stratigraphic sections of Upper Cretaceous hemipelagic and pelagic sequences of northern Bey Da?lar? Autochthon (western Taurides) yield six biozones such as, Dicarinella concavata Interval Zone, Dicarinella asymetrica Range Zone, Radotruncana calcarata Range Zone, Globotruncana falsostuarti Partial Range Zone, Gansserina gansseri Interval Zone, and Abathomphalus mayaroensis Concurrent Range Zone. Two of the zones, Dicarinella concavata Zone and Dicarinella asymetrica Zone, are identified in the massive hemipelagic limestones of the Bey Da?lar? Formation, of Coniacian-Santonian age. They are characterized by scarce planktonic foraminifera and abundant calcisphaerulids. The other four biozones are determined from the cherty pelagic limestones of the Akda? Formation and indicate a late Campanian-late Maastrichtian time interval. The planktonic foraminifera observed in these four biozones are diverse, complex morphotypes (K-selection), suggesting open oceans. The assemblage of the Abathomphalus mayaroensis Zone shows that the latest Maastrichtian record is absent throughout the northern part of the autochthon. Two main sedimentary hiatuses are recognized within the Upper Cretaceous pelagic sequence. Early to middle Campanian and latest Maastrichtian-middle Paleocene planktonic foraminifera are absent in all measured stratigraphic sections. Hiatus durations differ between sections as a result of diachronism of onset of the hemipelagic and pelagic deposition and the post-Santonian and post-Maastrichtian erosional phases. Drowning event and the early-middle Campanian and latest Maastrichtian-middle Paleocene hiatuses in the pelagic sequence are attributed to regional tectonics during the Late Cretaceous.     

Geodynamic formation settings of Ordovician and Devonian dike complexes in ophiolitic sections of the Southern Urals and Mugodzhary

The dike and volcanic complexes in the upper parts of the ophiolitic sections in the Paleozoides of the South Urals and Mugodzhary are Ordovician and Devonian in age. Two types of Ordovician complexes are distinguished by petrology and geochemistry. One of these types is characterized by a suprasubduction forearc formation setting and the second type developed in spreading basins in close proximity to island arcs. The Ordovician dikes formed in the setting of suprasubduction forearc spreading occur as blocks in the melange of the Sakmara Zone. Zircons from the plagiogranite associated with the dikes are dated at 456 ± 4 Ma. The Polyakovka dike complex in the north of the Cis-Sakmara-Voznesenka Zone is associated with basalts and cherts containing Ordovician conodonts. The dikes were probably formed during subduction of the spreading center; contributions of mantle-plume and subduction-related components are noted. Dike and volcanic complexes of Early-Middle Devonian age determined using isotopic and biostratigraphic methods are widespread. Two groups of complexes are distinguished by structural and geochemical features. The first group was formed in the setting of dispersed spreading in the second half of the Early Devonian. Boninites occur among the rocks of this group. The second group was formed in the setting of fast focused backarc spreading that developed up to the late Eifelian. Dike-in-dike suites close to the first group in composition cut through the Early Eifelian island-arc complexes in the frontal part of the arc. Zircons from the granitoid veins accompanying these dolerite dikes are dated at 391.9 ± 3 Ma (late Eifelian).     

Barremian ammonite faunas from the western High Atlas,Morocco – biostratigraphy and palaeobiogeography

An analysis of the stratigraphic distribution of ammonite faunas collected from several sections in the Essaouira-Agadir area (western High Atlas, Morocco) has enabled the establishment of a detailed succession of assemblages for the uppermost Hauterivian to lower Upper Barremian interval. All Mediterranean standard zones of this interval have been identified. The correlation potential of bioevents which define and characterise these units is discussed. Two significant regional hiatuses, one at the Hauterivian/Barremian boundary, the other involving the lower part of the Kotetishvilia nicklesi Zone, are related to third-order sea level falls. Moreover, the upper part of the succession corresponding to the upper Toxancyloceras vandenheckii Zone and the entire Heinzia sartousiana Zone is markedly condensed. The taxonomic composition of the ammonite assemblage reveals a strong Mediterranean character, yet, it shows some peculiar features as well.