贵州断杉剖面长兴期晚期腕足动物群及其地质意义

贵州断杉剖面长兴阶上部发现的腕足类化石包括:Paracrurithyris pigmaea,Attenuatella mengi,Neochonetes (Huangichonetes) substrophomenoides,Spinomarginifera kueichowensis,Anidanthus mucronata,? Hustedia orbicostata,Pygmochonetes sp.,Crurithyris sp.和Martinia sp..通过对该腕足动物群的分析以及和其他地区同时期的腕足动物群的对比,认为断杉剖面腕足动物群是深水分子与浅水分子混生的动物群,同时也是暖水分子与凉水分子混生的动物群.深水分子与浅水分子混生的特征与长兴期晚期断杉剖面位于深水盆地相的边缘,并且离浅水碳酸盐岩台地较近的古地理位置一致;暖水分子与凉水分子混生暗示扬子海盆当时可能存在洋流活动.     

煤山D剖面的放射虫动物群与海平面变化

煤山D剖面长兴组的放射虫动物群的研究成果很少.对煤山D剖面的放射虫动物群进行了详细的鉴定、个体数量和种的数量的统计.结果表明: 煤山D剖面长兴组的放射虫动物群的相对丰度、简单分异度与长兴期海平面变化具有耦合性: 放射虫丰度、分异度较大的层位基本对应于长兴早期和长兴晚期2次最大海侵事件发生的层位.长兴早期放射虫的丰度和分异度较大(相对长兴晚期而言), 这与长兴早期水体相对较深有关.煤山剖面放射虫动物群与海平面变化之间的这种耦合性为海平面变化的研究提供了依据.      

重庆中梁山长兴组腕足动物组合层序

<正> 重庆中梁山北风井剖面经杨遵仪等(1987)和朱梅丽、张世家(1987)研究后,目前已成为华南地区长兴阶重要剖面之一。笔者曾在此详细采集了长兴组的腕足动物化石。现就腕足动物群性质、组合序列等问题作一探讨。 野外工作期间,得到了重庆煤校张世家的帮助,室内整理期间朱梅丽给予了帮助,廖     

四川广元上寺剖面长兴阶放射虫动物群演变及控制因素

对四川广元上寺剖面大隆组的放射虫动物群进行了详细的鉴定和丰度、分异度的统计。发现该放射虫动物群丰度和分异度均较低,以泡沫虫和内射虫为主,含少量十字多囊虫的分子;其丰度和分异度与长兴期海平面变化具有很好的耦合关系:放射虫丰度、分异度较大的层位对应于长兴早期和长兴晚期两次最大海侵事件发生的层位。相对长兴晚期而言,长兴早期放射虫的丰度和分异度较大,这与长兴早期水体相对较深有关。此外,有孔虫与放射虫丰度变化呈现很好的负相关性,这与它们不同的生活习性和水深的变化有关。分析表明:水深的变化是上寺剖面放射虫动物群演变的主要控制因素。     

浙江长兴煤山地区二叠-三叠系界线底粘土中动物化石的发现及其意义

<正> 浙江长兴煤山地区是我国南部上二叠统长兴阶及二叠-三叠系界线候选层型剖面的所在地。近十年来,我们先后在本区测制了6条上二叠统长兴阶及二叠-三叠系界线剖面,即剖面A.B.C.D.E和Z(Sheng et al.,1984)把下三叠统下青龙组底部的混生动物群层自下而上分成混生层1、2和3三层,混生层1包括两部分,下部为伊利石-蒙脱石粘土层,亦称底粘土(basal clay),上部为黑色泥岩,当时没有在底粘土发现化石。此后,一     

福建的长兴阶

福建长兴期地层发育,包括碎屑岩相的大隆组和灰岩相的长兴组,长兴组分布于大田及其与永安、漳平交界处,大隆组主要分布于闽西南地区。根据生物群特征,建立了全省长兴阶7个生物带,并和华南地区长兴阶生物群作了对比。论证了福建长兴阶底界应划在大隆组下部,以Oldhamina squamosa 为代表的含海相腕足化石层下部砂岩之底。省内通常划归翠屏山组第四段的海相层应划归长兴阶。福建的长兴组含长兴阶上部生物群,其下含长兴阶下部生物群,福建长若灰岩应为长兴阶上部,大致为大隆组中上部的相变,其所含 Palaeofusulina sinensis带相当于大隆组上部 Pseudotirolites-Pleuronodoceras 带。     

苏浙皖边界地区苏皖运动的有关问题

苏皖运动的存在于否,对研究苏浙皖边界地区的地质发展史和正确认识长兴阶地层有重要意义。笔者论证了长兴组的厚度变化、界线粘土层的性质与成因、底砾岩的确认和地层接触关系、古生物群的突变等问题,认为:1)区内苏皖运动是存在的;2)砺山-江阴海堤不可否定;将安徽广德牛头山经江苏宜兴至江阴条带内的龙潭组上部地层作为长兴组的相变产物是不妥的。      

藏北双湖地区才多茶卡一带构造混杂岩中发现晚泥盆世和晚二叠世放射虫硅质岩

报道了在西藏北部双湖才多茶卡地区新发现的晚泥盆世和晚二叠世放射虫硅质岩,实测剖面的第9层硅质岩以产Neoalbaillella动物群为特征,其中N.ormithoformis,N.optima是晚二叠世长兴阶的2个带化石;第14层硅质岩以产Entactinids动物群为特征,其中Stigmosphaerostylusoumonhaoensis,Triloneheechinata,Archocyrtiumriedeli等主要见于晚泥盆世法门阶。上述2个动物群在西藏尚属首次发现。才多茶卡地区晚古生代放射虫硅质岩的发现为重新认识双湖构造混杂岩带的形成时代、构造环境、“构造带是否东延”等重大地质问题,提供了新的重要资料。     

广西隆林祥播地区中,晚二叠世有孔虫动物群

文章研究了广西隆林祥播地区中二叠统茅口阶,上二叠统吴家坪阶,长兴阶的有孔虫动物群,计有２２属５５种,７个未定种,分属于５个超科中的１２科。并由下而上建立５个有孔虫组合,介绍了各组合特征。     

二叠-三叠纪转折期放射虫动物群的变化

综述了二叠 -三叠纪转折期放射虫动物群的研究进展 ,长兴阶晚期放射虫动物群 90 %以上的种在二叠纪末期灭绝 ,只有少数在浅海灰岩和远洋硅质岩中均能够发现的属种才成功残存到三叠纪 ;三叠纪放射虫的复苏和辐射经历了较长的过程 ,Griesbachian至 Smithian为放射虫残存期 ,Spathian 为放射虫的复苏期 ,Anisian是放射虫的辐射期。Anisian放射虫的辐射受到强缺氧事件的影响。     

湘南当冲组底部不存在硅质层

<正> 湖南邵阳—耒阳相当于茅口组层位的岩性特殊,名当冲组,一般认为当冲组属茅口组相变所致。当冲组即当冲层,由田奇(王崔乃)、徐瑞麟于1936年创名,地点在湖南邵东县保和堂煤田南端的当冲(楼冲和长冲坪一带)。 当冲组在湘南分布稀散,露头普遍很差。其岩性与茅口组差异甚大,不少地质工作者     

皖南与湘西晚震旦世地层的划分与对比

<正> 中国南方晚震旦世地层,在斜坡—盆地相区,其上部有一套硅质岩,皖南称皮园村组,湘西及湘中称留茶坡组。长期以来,不少研究者都把这套硅质岩地层与灯影组对比,并以此来解释沉积环境及古地理。 笔者对浙西及皖南地区的晚震旦世地层进行了研究之后,曾对皮园村组的涵义作了修订,认为它仅相当于西峰寺组上段或灯影组上段(唐天福等,1981)。近几年来,笔者又     

1∶25万比如县幅、丁青县幅、嘉黎县幅、边坝县幅地质调查成果与进展

在丁青蛇绿岩以西的色扎岩体顶部单元硅质岩中首次发现早侏罗世菊石化石;在丁青县雪拉山口南的雀莫错组、布曲组中新采获双壳、桦树等化石;在巴青县雅安大山雀莫错组、马里组板岩中新采获云雀贝化石;边坝县的多尼组可分为3套岩性组合,在灰岩中发现大量的双壳类化石,可望建立一个新的岩性地层单位;拉孜北凼木曲东岸的拉贡塘组碳酸盐岩应为一套多旋回凝灰岩,发现丰富的苏铁类和真蕨类植物化石,具有晚侏罗世至早白垩世植被面貌;在索县次汝乡北多尼组中新发现白云母花岗岩岩滴;将嘉黎断裂带南侧娘蒲乡至错高乡一带的原蒙拉组解体为4套地层,并在其中发现变质侵入体;新发现几处蛇绿岩。     

Depositional and Ecological Features of Permian Oxygen Deficient Deposits at Shangsi Section, Northeast Sichuan, China

Because oxygen deficient conditions enhance the preservation of depositional organic matter, analysis on paleooxygenation conditions of depositional environments becomes a routine work in evaluations of potential hydrocarbon source rocks. The article focuses on depositional and ecological features relating to oxygen deficient shelfal environments at the Shangsi (上寺) Section, as a part of multidiscipline collaboration to reevaluate the hydrocarbon potential of the Middle and Upper Permian, Guangyuan (广元), Northeast Sichuan (四川) Province. Icbnofabric Zoophycos, sepioilte-bearing limestones (SBL) were interpreted as indicators of dysaerobic environments. Laminated calcareous and/or siliceous mudstones with pelagic ammonites and radiolarians were believed to be the deposits of anaerobic environments. When rhythmic succession was considered, average strategy was adopted for the oxygenation explanation of a given intervaL The anaerobic condition in this Permian section was observed in the upper part of the latest Permian Dalong (大隆) Formation, in which siliceous mudstones with ammonite, radiolarians develop in association with lower U/Mo ratio, lower biomarker ratio of Pr/Ph, and the highest TOC content. The topmost Maokou (茅口) Formation, featured by thin-bedded calcareous and siliceous mudstones with ammonite, thin-shelled bivalves, and laminations would be deposits of the quasianaerobic condition. The middle part of the Members and Ⅲ of the Chihsia Formation is proposed to be dysaerobic condition as indicated by occurrences of SBL and ichnofabric features, with the Member Ⅲ being the severe dysaerobic condition.     

江苏宁镇山脉仑山灰岩的新认识

“仑山灰岩”标准地点在江苏南部句容县的仑山。1933年,俞建章在研究“仑山灰岩”中的头足类动物群时,曾指出:“仑山灰岩”的时代应属于早、中奥陶世。1935年,李捷等在系统研究宁镇山脉地质时,对“仑山灰岩”重新进行划分,把上部含鞘角石(Vaginoceras)动物群的灰岩归入中奥陶统,称汤山灰岩。     

A review of Lower and Middle Palaeozoic biostratigraphy in west peninsular Malaysia and southern Thailand in its context within the Sibumasu Terrane

Fossils from the Cambrian to Devonian rocks of southern Thailand, the Langkawi Islands, mainland Kedah, Perlis, north Perak and central West Peninsular Malaysia are listed and reviewed, and their stratigraphy and correlation reassessed. The hitherto anomalous record of the trilobite Dalmanitina from Malaysia is reviewed and found to be of latest Ordovician (Hirnantian) age, rather than Lower Silurian age as previously reported, and is considered a probable synonym of the widespread Mucronaspis mucronata. A new stratigraphical nomenclature is erected for part of the Langkawi, mainland Kedah and Perlis area successions, in which the term Setul Limestone (which stretched from the Ordovician to the Devonian) is abandoned and replaced by the Middle Ordovician Kaki Bukit Limestone, the late Ordovician and early Silurian Tanjong Dendang Formation, the Silurian Mempelam Limestone, and the early Devonian Timah Tasoh Formation, all underlying the paraconformity with the late Devonian Langgun Red Beds. There was a single depositional basin in the generally shallow-water and cratonic areas of southern Thailand, Langkawi, and mainland Kedah and Perlis, in contrast to the deeper-water basin of north Perak. Only Silurian rocks are dated with certainty within another basin in central West Malaysia, near Kuala Lumpur, which were also cratonic and shallow-water, although to the east in west Pahang there are basal Devonian deeper-water sediments with graptolites. The area is reviewed in its position within the Sibumasu Terrane, which, in the Palaeozoic, also included central and northern Thailand, Burma (Myanmar) and southwest China (part of Yunnan Province).     

赣东北构造带中的“放射虫硅质岩”不是“茅口组硅质岩”

赣东北构造带中的“放射虫硅质岩”主要分布于樟树墩—茅桥一带的赣东北蛇绿杂岩带之张村群中,与周边岩石地层呈断层接触关系,矿物成分和化学成分一致显示为泥质硅质岩,岩石遭受低级绿片岩相区域变质作用的改造,与泥质千枚岩、变质火山岩、蛇绿岩密切共生,含有“可疑的”晚古生代放射虫化石;茅口(孤峰)组硅质岩遍布于赣东北—皖南广大地区,整合于乐平组煤系地层之下、小江边组灰岩之上,具稳定的层位压盖关系,矿物成分和化学成分反映为纯硅质岩,岩石无变质重结晶现象,与碳质泥岩、灰岩互层,含大量的、珊瑚及腕足类化石,地层时代为二叠纪。因此,两者应分属不同的地层单位。     

Erratum to “The Albian-Cenomanian boundary at Eggardon Hill, Dorset (England): An anomaly resolved?” [Proc. Geol. Assoc. 120 (2009) 108-120]

Re-examination of the classic exposures of the Eggardon Grit (topmost Upper Greensand Formation) at Eggardon Hill, Dorset shows that the upper part of this unit has a more complex stratigraphy than has been previously recognised. The Eggardon Grit Member, as described herein, is capped by a hardground and associated conglomerate, and is entirely of Late Albian age. The hardground is probably the lateral equivalent of the Small Cove Hardground, which marks the top of the Upper Greensand succession in southeast Devon. The conglomerate is overlain by a thin sandy limestone containing Early Cenomanian ammonites. This limestone is almost certainly the horizon of the Early Cenomanian ammonite fauna that has previously been attributed to the top of the Eggardon Grit. The limestone is regarded as a thin lateral equivalent of the Beer Head Limestone Formation (formerly Cenomanian Limestone) exposed on the southeast Devon coast. The fauna of the limestone at Eggardon suggests that it is probably the age equivalent to the two lowest subdivisions of the Beer Head Limestone in southeast Devon, with a remanié fauna of the Pounds Pool Sandy Limestone Member combined with indigenous macrofossils of the Hooken Nodular Limestone Member. The next highest subdivision of the Beer Head Limestone in southeast Devon (Little Beach Bioclastic Limestone Member), equates with the ammonite-rich phosphatic conglomerate of the ‘Chalk Basement Bed’, which caps the Beer Head Limestone at Eggardon, and which was previously regarded as the base of the Chalk Group on Eggardon Hill.Petrographic analysis of the Eggardon Grit shows that lithologically it should more correctly be described as a sandy limestone rather than sandstone. The original stratigraphical definition of the unit should probably be modified to exclude the softer, nodular calcareous sandstones that have traditionally been included in the lower part of the member.Without the apparently clear evidence of unbroken sedimentation across the Albian-Cenomanian boundary, suggested by the previous interpretation of the Eggardon succession, it is harder to argue for this being a prevalent feature of Upper Greensand stratigraphy in southwest England. Correlation of the Eggardon succession with successions in Dorset and southeast Devon reveals a widespread regional break in sedimentation at the Albian-Cenomanian boundary. The sand-rich facies above this unconformity represent the true base of the Chalk Group, rather than the ‘Chalk Basement Bed’ of previous interpretations.Selected elements of regionally important Upper Greensand ammonite faunas previously reported from Shapwick Quarry, near Lyme Regis, and Babcombe Copse, near Newton Abbot, are newly figured herein.     

西秦岭中志留统“硅、灰、泥岩”型层控铀矿的沉积特征及控矿条件

本文详细研究了西秦岭南带中志留统“硅、灰、泥岩”型层控铀矿含矿岩系的沉积相类型及特征,查明了本区中志留世各期的岩相古地理特征。着重讨论了铀矿田内控矿的地质条件。     

The Albian–Cenomanian boundary at Eggardon Hill,Dorset (England): an anomaly resolved?

Re-examination of the classic exposures of the Eggardon Grit (topmost Upper Greensand Formation) at Eggardon Hill, Dorset shows that the upper part of this unit has a more complex stratigraphy than has been previously recognised. The Eggardon Grit Member, as described herein, is capped by a hardground and associated conglomerate, and is entirely of Late Albian age. The hardground is probably the lateral equivalent of the Small Cove Hardground, which marks the top of the Upper Greensand succession in southeast Devon. The conglomerate is overlain by a thin sandy limestone containing Early Cenomanian ammonites. This limestone is almost certainly the horizon of the Early Cenomanian ammonite fauna that has previously been attributed to the top of the Eggardon Grit. The limestone is regarded as a thin lateral equivalent of the Beer Head Limestone Formation (formerly Cenomanian Limestone) exposed on the southeast Devon coast. The fauna of the limestone at Eggardon suggests that it is probably the age equivalent to the two lowest subdivisions of the Beer Head Limestone in southeast Devon, with a remanié fauna of the Pounds Pool Sandy Limestone Member combined with indigenous macrofossils of the Hooken Nodular Limestone Member. The next highest subdivision of the Beer Head Limestone in southeast Devon (Little Beach Bioclastic Limestone Member), equates with the ammonite-rich phosphatic conglomerate of the ‘Chalk Basement Bed’, which caps the Beer Head Limestone at Eggardon, and which was previously regarded as the base of the Chalk Group on Eggardon Hill.Petrographic analysis of the Eggardon Grit shows that lithologically it should more correctly be described as a sandy limestone rather than sandstone. The original stratigraphical definition of the unit should probably be modified to exclude the softer, nodular calcareous sandstones that have traditionally been included in the lower part of the member.Without the apparently clear evidence of unbroken sedimentation across the Albian–Cenomanian boundary, suggested by the previous interpretation of the Eggardon succession, it is harder to argue for this being a prevalent feature of Upper Greensand stratigraphy in southwest England. Correlation of the Eggardon succession with successions in Dorset and southeast Devon reveals a widespread regional break in sedimentation at the Albian–Cenomanian boundary. The sand-rich facies above this unconformity represent the true base of the Chalk Group, rather than the ‘Chalk Basement Bed’ of previous interpretations.Selected elements of regionally important Upper Greensand ammonite faunas previously reported from Shapwick Quarry, near Lyme Regis, and Babcombe Copse, near Newton Abbot, are newly figured herein.