The upper Viséan–Serpukhovian in the type area for the Serpukhovian Stage (Moscow Basin,Russia): Part 1. Sequences,disconformities, and biostratigraphic summary

The upper Viséan–Serpukhovian strata in the type region for the Serpukhovian Stage is an epeiric‐sea succession ca. 90 m in thickness. The predominantly Viséan Oka Group (comprising the Aleksin, Mikhailov, and Venev formations) is dominated by photozoan packstones with fluvial siliciclastic wedges developed from the west. The Lower Serpukhovian Zaborie Group is composed of the Tarusa and Gurovo formations. The latter is a new name for the shale‐dominated unit of Steshevian Substage age in the studied area. The Zaborie Group is composed of limestones and marls in its lower (Tarusa and basal Gurovo) part and black smectitic to grey palygorskitic shales in the main part of the Gurovo Formation. The Gurovo Formation is capped by a thin limestone with oncoids and a palygorskitic–calcretic palaeosol. The Upper Serpukhovian is composed of a thin (3–12 m) Protva Limestone heavily karstified during a mid‐Carboniferous lowstand. The succession shows a number of unusual sedimentary features, such as a lack of high‐energy facies, shallow‐subtidal marine sediments penetrated by Stigmaria, the inferred atidal to microtidal regime, and palustrine beds composed of saponitic marls. The succession contains many subaerial disconformities characterized by profiles ranging from undercoal solution horizons to palaeokarsts. Incised fluvial channels are reported at two stratigraphic levels to the west of the study area. The deepest incisions developed from the Kholm Disconformity (top of the Mikhailov Formation). This disconformity also exhibits the deepest palaeokarst profile and represents the major hiatus in the Oka–Zaborie succession. The new sea‐level curve presented herein shows two major cycles separated by the Kholm Unconformity at the Mikhailov/Venev boundary. The Lower Serpukhovian transgression moved the base‐level away from falling below the seafloor so that the section becomes conformable above the Forino Disconformity (lower Tarusa). The maximum deepening is interpreted to occur in the lower dark‐shale part of the Gurovo Formation. The base of the Serpukhovian Stage is defined by FADs of the conodont Lochriea ziegleri and the foraminifer Janischewskina delicata in the middle of the sequence VN2. The Aleksinian–Mikhailovian interval is provisionally correlated with the Asbian (Lower–Middle Warnantian) in Western Europe. Based on FODs of Janischewskina typica and first representatives of Climacammina, the Venevian is correlated with the Brigantian in Western Europe. The Tarusian–Protvian interval contains diverse fusulinid and conodont assemblages, but few forms suitable for international correlation. FADs of the zonal conodont species Adetognathus unicornis and Gnathodus bollandensis at several metres above the Protvian base suggest correlation of the entire Zaborie Group and may be the basal Protvian to the Pendleian. Copyright © 2014 John Wiley & Sons, Ltd.     

Biostratigraphy,microfacies and depositional environments of upper Viséan limestones from the Burren region,County Clare,Ireland

The Burren region in western Ireland contains an almost continuous record of Viséan (Middle Mississippian) carbonate deposition extending from Chadian to Brigantian times, represented by three formations: the Chadian to Holkerian Tubber Formation, the Asbian Burren Formation and the Brigantian Slievenaglasha Formation. The upper Viséan (Holkerian–Brigantian) platform carbonate succession of the Burren can be subdivided into six distinct depositional units outlined below. (1) An Holkerian to lower Asbian unit of skeletal peloidal and bryozoan bedded limestone. (2) Lower Asbian unit of massive light grey Koninckopora‐rich limestone, representing a shallower marine facies. (3) Upper Asbian terraced limestone unit with minor shallowing‐upward cycles of poorly bedded Kamaenella‐rich limestone with shell bands and palaeokarst features. This unit is very similar to other cyclic sequences of late Asbian age in southern Ireland and western Europe, suggesting a glacio‐eustatic origin for this fourth‐order cyclicity. (4) Lower Brigantian unit with cyclic alternations of crinoidal/bryozoan limestone and peloidal limestone with coral thickets. These cycles lack evidence of subaerial exposure. (5) Lower Brigantian bedded cherty dark grey limestone unit, deposited during the maximum transgressive phase of the Brigantian. (6) Lower to upper Brigantian unit mostly comprising cyclic bryozoan/crinoidal cherty limestone. In most areas this youngest unit is truncated and unconformably overlain by Serpukhovian siliciclastic rocks. Deepening enhanced by platform‐wide subsidence strongly influenced later Brigantian cycle development in Ireland, but localized rapid shallowing led to emergence at the end of the Brigantian. A Cf5 Zone (Holkerian) assemblage of microfossils is recorded from the Tubber Formation at Black Head, but in the Ballard Bridge section the top of the formation has Cf6 Zone (Asbian) foraminiferans. A typical upper Asbian Rugose Coral Assemblage G near the top of the Burren Formation is replaced by a lower Brigantian Rugose Coral Assemblage H in the Slievenaglasha Formation. A similar change in the foraminiferans and calcareous algae at this Asbian–Brigantian formation boundary is recognized by the presence of upper Asbian Cf6γ Subzone taxa in the Burren Formation including Cribrostomum lecomptei, Koskinobigenerina sp., Bradyina rotula and Howchinia bradyana, and in the Slievenaglasha Formation abundant Asteroarchaediscus spp., Neoarchaediscus spp. and Fasciella crustosa of the Brigantian Cf6δ Subzone. The uppermost beds of the Slievenaglasha Formation contain a rare and unusual foraminiferal assemblage containing evolved archaediscids close to tenuis stage indicating a late Brigantian age. Copyright © 2006 John Wiley & Sons, Ltd.     

Correlation of Mississippian (Upper Viséan) foraminiferan,conodont, miospore and ammonoid zonal schemes,and correlation with the Asbian–Brigantian boundary in northwest Ireland

The microbiota of the upper Viséan (Asbian–Brigantian) rocks in the Lough Allen Basin in northwest Ireland is analysed. The Middle Mississippian sequence studied extends from the upper part of the Dartry Limestone/Bricklieve Limestone formations of the Tyrone Group to the Carraun Shale Formation of the Leitrim Group. The rocks have been traditionally dated by ammonoid faunas representing the B_2a to P_2c subzones. The Meenymore Formation (base of the Leitrim Group) also contains conodont faunas of the informal partial‐range Mestognathus bipluti zone. The upper Brigantian Lochriea nodosa Conodont Zone was recognized by previous authors in the middle of the Carraun Shale Formation (Ardvarney Limestone Member), where it coincides with upper Brigantian ammonoids of the Lusitanoceras granosus Subzone (P_2a). Foraminifera and algae in the top of the Dartry Limestone Formation are assigned to the upper Cf6γ Foraminifera Subzone (highest Asbian), whereas those in the Meenymore Formation belong to the lower Cf6δ Foraminifera Subzone (lower Brigantian). The Dartry Limestone Formation–Meenymore Formation boundary is thus correlated with the Asbian–Brigantian boundary in northwest Ireland. For the first time, based on new data, a correlation between the ammonoid, miospore, foraminiferan and conodont zonal schemes is demonstrated. The foraminiferans and algae, conodonts and ammonoids are compared with those from other basins in Ireland, northern England, and the German Rhenish Massif. Historically, the Asbian–Brigantian boundary has been correlated with several levels within the P_1a Ammonoid Subzone. However, the new integrated biostratigraphical data indicate that the Asbian–Brigantian boundary in northwest Ireland is probably located within the B_2a Ammonoid Subzone and the NM Miospore Zone, but the scarcity of ammonoids in the Tyrone Group precludes an accurate placement of that boundary within this subzone. Copyright © 2006 John Wiley & Sons, Ltd.     

Stratigraphy of upper Viséan carbonate platform rocks in the Carlow area,southeast Ireland

The stratigraphy of the upper Viséan (Asbian to Brigantian) carbonate succession in southeast Ireland is revised on the basis of seven quarry and two borehole sections. Six lithological units have been distinguished, two units (units 1 and 2) in the upper Asbian Ballyadams Formation, and four units (units 4 to 6) in the Brigantian Clogrenan Formation (both formations are dated precisely using foraminiferans, calcareous algae and rugose corals). The boundary between the Ballyadams and Clogrenan formations is redefined 19 m below the horizon proposed by the Geological Survey of Ireland, and thus, lithological characteristics of both formations are redescribed. The upper part of the Ballyadams Formation is characterized by well‐developed large‐scale cyclicity, with common subaerial exposure surfaces. Fine‐ to medium‐grained thin‐bedded limestones with thin shales occur in the lower part of cycles, passing up into medium‐grained pale grey massive limestones in the upper part. The Clogrenan Formation is composed mainly of medium‐ to coarse‐grained thick limestone beds with variable presence of shales; but no large‐scale cyclicity. There is a decrease in the number of subaerial exposure surfaces towards the top of the formation and common chert nodules; macrofauna occurs mostly concentrated in bands. The six units recognized in the Carlow area are comparable with other units described for the same time interval (Asbian–Brigantian) from south and southwest Ireland, demonstrating the existence of a stable platform for most parts of southern Ireland, controlled principally by glacioeustatics. Copyright © 2004 John Wiley & Sons, Ltd.     

Late Viséan–Serpukhovian foraminiferans and calcareous algae from the Adarouch region (central Morocco), North Africa

Three Upper Viséan to Serpukhovian limestone formations from the Adarouch region (central Morocco), North Africa, have been dated precisely using foraminiferans and calcareous algae. The lower and middle part of the oldest formation, the Tizra Formation (Fm), is assigned to the latest Asbian (upper Cf6γ Subzone), and its upper part to the Early Brigantian (lower Cf6δ Subzone). The topmost beds of this formation are assigned to the Late Brigantian (upper Cf6δ Subzone). The lower part of the succeeding Mouarhaz Fm is also assigned to the Late Brigantian (upper Cf6δ Subzone). The Akerchi Fm is younger than the other formations within the region, ranging from the latest Brigantian (uppermost Cf6δ Subzone) up to the Serpukhovian (E₁–E₂). The base of the Serpukhovian (Pendleian Substage, E₁) is repositioned, to coincide with the appearance of a suite of foraminiferans including Archaediscus at tenuis stage, Endothyranopsis plana, Eostaffella pseudostruvei, Loeblichia ukrainica, Loeblichia aff. minima and Biseriella? sp. 1. The upper Serpukhovian (Arnsbergian Substage, E₂) is marked by the first appearance of Eostaffellina ex. gr. paraprotvae and Globoomphalotis aff. pseudosamarica. The biostratigraphical scheme used for the reassessment of the foraminiferal zones and subzones in the Adarouch area closely compares with that for the British succession in northern England (Pennine Region), where the stratotypes of the Upper Viséan (Asbian and Brigantian) and Early Serpukhovian (Pendleian) substages are located. Thus, a succession equivalent to an interval from the Melmerby Scar Limestone to the Great (or Little) Limestone is recognized. These assemblages are also compared to other foraminiferal zones proposed in other regions of Morocco. Several foraminiferans have been identified that are proposed as potential Serpukhovian markers for other basins in Western Europe, and compared to sequences in Russia and the Donets Basin, Ukraine. Copyright © 2008 John Wiley & Sons, Ltd.     

Foraminifers and conodonts from the late Viséan to early Bashkirian succession in the Saharan Tindouf Basin (southern Morocco): biostratigraphic refinements and implications for correlations in the western Palaeotethys

The Carboniferous succession in the Tindouf Basin of southern Morocco, North Africa, displays Mississippian to Early Pennsylvanian marine beds, followed by Pennsylvanian continental deposits. The marine beds comprise a shallow water cyclic platform sequence, dominated by shales and fine‐grained sandstones with thin but laterally persistent limestone/dolostone beds. Foraminiferal assemblages have been studied in the limestone beds in several sections from the Djebel Ouarkziz range in the northern limb of the Tindouf Syncline; they indicate that the age of the limestones range from late Asbian (late Viséan) to Krasnopolyanian (early Bashkirian). The foraminiferal assemblages are abundant and diverse, and much richer in diversity than those suggested by previous studies in the region, as well as for other areas of the western Palaeotethys. The richest assemblages are recorded in the Serpukhovian but, unusually, they contain several taxa which appear much earlier in Western European basins (in the latest Viséan). In contrast, conodont assemblages are scarce due to the shallow‐water facies, although some important taxa are recorded in the youngest limestones. Copyright © 2013 John Wiley & Sons, Ltd.     

Event Stratigraphy, Biostratigraphy and Sequence Stratigraphy of Neoproterozoic in North China

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Latest Tournaisian–late Viséan foraminiferal biozonation (MFZ8–MFZ14) of the Valiabad area,northwestern Alborz (Iran): geological implications

The Mobarak Formation in the Valiabad area (northwestern Alborz, Iran) is composed of bioclastic, oolitic and sandy limestone interbedded with black shale, and is disconformably underlain and overlain by the Cambrian Lalun and Permian Dorud formations, respectively. In this study, 104 foraminiferal species belonging to 12 families and 33 genera were determined. Among them, six genera and nine species are reported for the first time in Iran. Analysis of the foraminiferal assemblages has identified eight local biozones, which can be correlated with the MFZ8 to MFZ14 zones of the Viséan stratotypes in Belgium. The Valiabad equivalents of these biozones are essentially characterized by (1) Eoparastaffella ex gr. rotunda‐‘florigena’–Lysella cf. gadukensis; (2) Eoparastaffella simplex–Lapparentidiscus bokanensis; (3) Ammarchaediscus; (4) Uralodiscus–Glomodiscus; (5) Glomodiscus–Archaediscus; (6) Pojarkovella–Mstinia fallax; (7) Mstinia bulloides–Pseudoendothyra; and (8) Howchinia gibba–Howchinia bradyana–Tubispirodiscus attenuatus. Consequently, the Valiabad section appears to be one of the most complete Viséan sections in Iran. Some taxonomic precisions are provided about the principal taxa. Biogeographically, (1) the MFZ8–MFZ11 biozones are extended to all the shelves of the Palaeotethys (from Ireland to South China) and Urals oceans; nevertheless, due to the complete evolution of archaediscoids, they seem more related to the Perigondwanan assemblages from Sinai and Taurus (including the Antalya Nappes); (2) the MFZ12 assemblage appears relatively endemic; and (3) the impoverished assemblages of the biozones MFZ13‐14 have marked affinities with the Kazakhstan Block. It is currently impossible to indicate precisely if these variations are related with a drift of the Alborz region to the north, or to a change of oceanic currents. Moreover, the double affinity highlights the narrowness of the Palaeotethys in Iran during the Viséan. Copyright © 2014 John Wiley & Sons, Ltd.     

东海陆架全新统高分辨率层序地层学研究

在高分辨率14C测年、岩石、生物、化学、同位素、气候及磁性地层学研究成果基础上,通过不同沉积背景典型钻孔的沉积学分析,运用层序地层学理论,对东海陆架全新统进行了高分辨率层序划分及对比;建立了全新世层序地层格架及海平面变化过程;提出了相应的层序成因模式。研究结果表明,东海陆架全新统相当于一个发育中的六级（1~10ka）层序,可进一步划分为3个七级（0.1~1ka）层序和若干个更次级层序。代表1个六级或3个七级周期相对海平面变化过程中叠加有若干更次级的海平面波动,它们与地球旋回谱系中的太阳带、历法带密切相关。七级层序具有与三级层序相近的内部构型和成因格架。在东海陆架全新世沉积演化过程中,长江三角州至少有3次不同程度地越过东海陆架进入冲绳海槽,并滞留有至少3层海侵改造"残积砂"沉积。在东海陆架全新世海平面变化期间,最大海平面时期为约距今6~5ka,大致高于现今海平面2~4m,最低海平面在距今10ka左右,大约低于现今海平面130m。目前,由于温室效应的影响,海平面仍呈小幅度波浪式上升。事实证明,层序地层学不仅丰富了现代海洋沉积学的内容,而且解决了许多海洋沉积学未能解决的问题.     

南海华南陆缘中生界层序地层模式与海平面变化

华南陆缘中生界地层以广东省出露最广,这套地层为陆源碎屑沉积岩,局部为火山岩。上三叠统—上白垩统划分为2个巨层序、7个超层序和15个层序。沉积充填序列展示出本地区经历了海侵-海退过程,沉积环境由海相转化为陆相环境。3个级别的海平面变化控制了层序、超层序和巨层序的发育。粤中--粤东地区中生界发育的Ⅲ级层序可归纳出3种类型:浅水型、深水型和湖盆型;浅水型层序又可以分为浅水Ⅰ型和浅水Ⅱ型。     

华南地区晚三叠世含煤岩系层序—古地理

在对露头及钻孔剖面沉积特征研究的基础上,建立了华南地区晚三叠世含煤岩系层序地层格架,恢复了基于三级层序的岩相古地理,并分析了聚煤规律。根据岩相特征及岩相组合类型,在区内晚三叠世含煤地层中识别出陆相和海陆过渡相两大沉积类型,并可进一步识别出冲积扇、河流(包括辫状河和曲流河)、三角洲、湖泊、潮坪—潟湖、滨海平原和滨浅海等7种沉积类型。陆相沉积主要发育在上扬子地区的四川盆地;海陆过渡相沉积主要发育在东南部湘赣粤滨浅海。在晚三叠世含煤岩系中识别出区域性不整合面和构造应力转换面、砂砾岩体底部冲刷面和岩性突变面等类型的层序界面,将含煤岩系划分为5个三级层序。以三级层序为古地理作图单元,恢复了研究区的古地理格局。由煤层厚度与岩相古地理平面展布规律可知,最有利的成煤环境为三角洲沉积体系,其次为河流、潮坪—潟湖沉积体系,聚煤中心主要分部在四川盆地的乐威煤田以及华蓥山煤田、湘赣粤滨浅海地区的湘东南至赣西萍乡一带。     

Conodont Biostratigraphy and Age Determination of the Lower–Middle Triassic Boundary in South Guizhou Province, China

The demarcation of the Lower–Middle Triassic boundary is a disputed problem in global stratigraphic research. Lower–Middle Triassic strata of different types, from platform to basin facies, are well developed in Southwest China. This is favorable for the study of the Olenekian–Anisian boundary and establishing a stratotype for the Qingyan Stage. Based on research at the Ganheqiao section in Wangmo county and the Qingyan section in Guiyang city, Guizhou province, six conodont zones have been recognized, which can be correlated with those in other regions, in ascending order as follows: 1, Neospathodus cristagalli Interval-Zone; 2, Neospathodus pakistanensis Interval-Zone; 3, Neospathodus waageni Interval-Zone; 4, Neospathodus homeri-N. triangularis Assemblage-Zone; 5, Chiosella timorensis Interval-Zone; and 6, Neogongdolella regalis Range-Zone. An evolutionary series of the Early–Middle Triassic conodont genera Neospathodus-Chiosella-Neogongdolella discovered in the Ganheqiao and Qingyan sections has an intermediate type named Neospathodus qingyanensis that appears between Neospathodus homeri and Chiosella timorensis in the upper part of the Neospathodus homeri-N. triangularis Zone, showing an excellent evolutionary relationship of conodonts near the Lower–Middle Triassic boundary. The Lower–Middle Triassic boundary is located at 1.5 m below the top of the Ziyun Formation, where Chiosella timorensis Zone first appears in the Qingyan section, whereas this boundary is located 0.5 m below the top of the Ziyun Formation, where Chiosella timorensis Zone first appears in the Ganheqiao section. There exists one nearly 6-m thick vitric tuff bed at the bottom of the Xinyuan Formation in the Ganheqiao section, which is usually regarded as a lithologic symbol of the Lower–Middle Triassic boundary in South China. Based on the analysis of high-precision and high-sensitivity Secondary Ion Mass Spectrum data, the zircon age of this tuff has a weighted mean 206Pb/238U age of 239.0±2.9Ma (2s), which is a directly measured zircon U-Pb age of the Lower–Middle Triassic boundary. The Ganheqiao section in Wangmo county can therefore provide an excellent section through the Lower–Middle Triassic because it is continuous, the evolution of the conodonts is distinctive and the regionally stable distributed vitric tuff near the Lower–Middle Triassic boundary can be regarded as a regional key isochronal layer. This section can be regarded not only as a standard section for the establishment of the Qingyan Stage in China, but also as a reference section for the GSSP of the Lower–Middle Triassic boundary.     

Biostratigraphy,sedimentology and palaeobathymetry of Waulsortian buildups and peri-Waulsortian rocks during the late Tournaisian regression,Dinant area,Belgium

Recent revision of the biostratigraphy allows the recognition of a stratigraphic entity (here termed Freyrian) between the base of the Moliniacian stage and the base of the Viséan and simplifies sedimentological interpretation of late Tournaisian events around Dinant, in Belgium. Petrographic analysis of Freyrian rocks in Waulsortian buildups and peri-Waulsortian facies reveals a pattern of carbonate sedimentation related to the submarine topography developed by the buildups, and to sea-level changes. Graded beds and thin layers of grainstone in the predominantly fine-grained peri-Waulsortian sediments represent influxes derived mainly from nearby buildups during a period of shallowing. Using the sequence of foraminiferan assemblages which colonized the buildups as a stratigraphic scale, the earlier influxes are shown to have occurred only close to the presumed source, whereas later influxes extended further and marked the culmination of the shallowing phase. Deposition during the latter part of the Freyrian appears to have occurred in rather deeper, less disturbed water. The Moliniacian and Viséan boundary stratotypes, both in peri-Waulsortian facies, are critically assessed because almost all the stratigraphically useful foraminiferans occur in the rare grainstones resulting from sediment influxes. Tetrataxis was one of the few foraminiferans to colonize proximal peri-Waulsortian areas and appears to have ranged to a water depth of about 200 m. Downslope diachronism of colonization is interpreted as evidence of a sea-level fall of about 140 m and is used to draw a sea-level curve for this late Tournaisian regression. Using the same depth scale, microbial coating extended to about 300 m and its development appears to have been related to low sedimentation rates rather than photic conditions. © 1997 John Wiley & Sons, Ltd.     

黔南上司地区石炭系有孔虫:兼论华南维宪阶有孔虫生物地层序列

石炭纪时期有孔虫具有演化快、分布广、数量丰富、分异度高的特点,对于地层的划分对比具有极为重要的意义。与全球其他重要的石炭纪沉积区相比,华南有孔虫生物地层划分精度相对较低。本文首次较为系统地报道了华南石炭系代表性岩石地层单位旧司组和上司组下部丰富的有孔虫化石及其在剖面上的分布情况,并综合现有关于华南的有孔虫化石资料,将华南维宪阶划分为7个有孔虫化石带,自下而上分别为Eoparastaffella simplex带、Viseidiscus/Planoarchaediscus带、Paraarchaediscus带、Pojarkovella nibelis带、Koskinotextularia带、Bradyina带和Janischewskina带。这些有孔虫带可与全球其他典型的石炭纪沉积区进行很好的对比,从而为相关的研究提供一个较为精细的地层格架。通过对黔南上司地区有孔虫的研究,提议中国石炭系区域性年代地层单位上司阶底界可用有孔虫Bradyina的首现定义,并将上司阶与西欧的Warnantian亚阶中上部和俄罗斯的Aleksinian亚阶—Venevian亚阶对比,对应国际维宪阶上部,为全球石炭系年代地层对比提供了可靠的化石依据。     

Ar–Ar Ages of Hydrothermal Muscovite and Igneous Biotite at the Guposhan–Huashan District,Northeast Guangxi,South China: Implications for Mesozoic W–Sn Mineralization

The Guposhan–Huashan district is an important W–Sn–Sb–Zn–(Cu) metallogenic area in South China. It is located in the middle‐west segment of the Nanling Range. Granitoids in the Guposhan–Huashan district possess certain properties of A‐type or I‐type granites. The W–Sn–Sb–Zn mineralization in the district is closely associated with magma emplacement. Two igneous biotite and seven hydrothermal muscovite samples from skarn, veins and greisenization ores were analyzed by Ar–Ar methods. Two igneous biotite samples from fine‐grained quartz monzodiorite and fine‐grained biotite granite show plateau ages of 168.7 ± 1.9 Ma and 165.0 ± 1.1 Ma, respectively. Seven hydrothermal muscovite samples from ores yield plateau ages as two groups: 165 Ma to 160 Ma and 104 Ma to 100 Ma. These data suggest that the emplacement of fine‐grained granitoids in this district is coeval with the main phase magma emplacement, different from previous studies. The W–Sn–Sb–Zn mineralization took place in two stages, i.e. the Middle–Late Jurassic and early Cretaceous. W–Sn mineralization in the Guposhan–Huashan district is closely related to the magmatism, which was strongly influenced by underplating of asthenospheric mantle along trans‐lithospheric deep faults and related fractures.     

西南地区二叠纪层序地层及海平面变化

西南地区二叠系可划分为2个二级层序、11个三级层序,它们代表11次三级海平面升降旋回,其中有6次可与欧美地区二叠纪海平面变化相对比,它们是伦纳德(Leonardian)早期、瓜达卢普(Guadalupian)早期、瓜达卢普(Guadalupian)晚期、卡赞(Kazanian)早期、鞑靼(Tatarian)早期和鞑靼(Tatarian)晚期的海平面旋回。研究表明,该区二叠纪相对海平面变化作为全球海平面变化和同沉积构造活动相互作用的产物,它与欧美地区乃至联合古陆发展具反向效应,即具有以海侵型碳酸盐沉积序列为典型的主体海平面上升的特点。作者认为显生宙全球海平面旋回曲线的二叠纪部分总体具有两种类型或分支:其一是以海侵型碳酸盐沉积序列为主的反映海平面主体上升的特提斯型或华南型;其二是以海陆过渡—陆相海退沉积序列为主的揭示海平面主体下降的经典型或欧美型。作者强调,全球二叠纪海侵型全球海平面旋回曲线应以西南地区为代表。     

Conodont Biostratigraphy and Age Determination of the Lower-Middle Triassic Boundary in South Guizhou Province,China

The demarcation of the Lower-Middle Triassic boundary is a disputed problem in global stratigraphic research.Lower-Middle Triassic strata of different types,from platform to basin facies, are well developed in Southwest China.This is favorable for the study of the Olenekian-Anisian boundary and establishing a stratotype for the Qingyan Stage.Based on research at the Ganheqiao section in Wangmo county and the Qingyan section in Guiyang city,Guizhou province,six conodont zones have been recognized,which ca...     

黔桂地区二叠系层序地层格架及相对海平面变化研究

黔桂地区的二叠系以其明显的相分异而引入注目,在连陆台地上发育煤系地层,而在连陆台地边缘及孤立台地上发育海绵生物礁,形成一个典型的“台－盆－丘－槽”的古地理格局,并且相分异最明显的时期正好是生物礁发育的时期。二叠系包括三个统即船山统、阳新统和乐平统,船山统与阳新统之交的黔桂运动主幕不整合面以及阳新统和乐平统之交的东吴运动主幕不整合面特征明显,同时还代表了沉积盆地性质发生较大变化的界面。在二叠系中,船山统与下伏石炭系顶部的地层构成1个三级沉积层序（SQ19）,阳新统包含4个三级层序（SQ20－SQ23）,乐平统包括2个三级层序（SQ24,SQ25）。该地区的另一个特别是在二叠纪与三叠纪之交发生了较为典型的台地淹没事件,形成一个较为典型的淹没不整合面。因此,层序界面类型可以根据其所代表的地质涵义而划分为四大类型：构造不整合面、沉积不整合面,淹没不整合面以及它们的相关面。     

Geological features and origin of the Huize carbonate-hosted Zn–Pb–(Ag) District, Yunnan, South China

The Huize Zn–Pb–(Ag) district, in the Sichuan–Yunnan–Guizhou Zn–Pb–(Ag) metallogenic region, contains significant high-grade, Zn–Pb–(Ag) deposits. The total metal reserve of Zn and Pb exceeds 5 Mt. The district has the following geological characteristics: (1) high ore grade (Zn + Pb ≥ 25 wt.%); (2) enrichment in Ag and a range of other trace elements (Ge, In, Ga, Cd, and Tl), with galena, sphalerite, and pyrite being the major carriers of Ag, Ge, Cd and Tl; (3) ore distribution controlled by both structural and lithological features; (4) simple and limited wall-rock alteration; (5) mineral zonation within the orebodies; and (6) the presence of evaporite layers in the ore-hosting wall rocks of the Early Carboniferous Baizuo Formation and the underlying basement.Fluid-inclusion and isotope geochemical data indicate that the ore fluid has homogenisation temperatures of 165–220 °C, and salinities of 6.6–12 wt.% NaCl equiv., and that the ore-forming fluids and metals were predominantly derived from the Kunyang Group basement rocks and the evaporite-bearing rocks of the cover strata. Ores were deposited along favourable, specific ore-controlling structures. The new laboratory and field studies indicate that the Huize Zn–Pb–(Ag) district is not a carbonate-replacement deposit containing massive sulphides, but rather the deposits can be designated as deformed, carbonate-hosted, MVT-type deposits. Detailed study of the deposits has provided new clues to the localisation of concealed orebodies in the Huize Zn–Pb–(Ag) district and of the potential for similar carbonate-hosted sulphide deposits elsewhere in NE Yunnan Province, as well as the Sichuan–Yunnan–Guizhou Zn–Pb–(Ag) metallogenic region.