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湖南益阳下奥陶统弗洛阶的笔石分带 总被引：1，自引：1，他引：0
根据对采自湖南益阳南坝剖面的笔石化石的研究,识别出了下奥陶统弗洛阶4个连续的笔石带(自下而上):Tetragraptus approximatus带、Pendeograptus fruticosus带、Didymograptellus bifidus带和Corymbograptus deflexus带。同时在特马豆克阶顶部也识别出了Hunnegraptus copiosus带,从而在该区确立了一个连续的、可与国内外同期地层精确对比的弗洛阶笔石带序列。 相似文献
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王文卉冯洪真李丽霞陈文建 《地层学杂志》2013,(2):155-168
报道了湖南益阳晚特马道克期至弗洛早期笔石页岩中的几丁石和疑源类化石,并识别出3个几丁石生物带以及3个疑源类组合带。几丁石、疑源类化石与笔石共生,使得识别出的几丁石带以及疑源类化石组合的时代可以根据笔石带校正。在江南斜坡区建立的连续的晚特马豆克期及弗洛期最早期的几丁石、疑源类序列,不但可与国内外同期地层进行精确对比,对于早奥陶世古生物地理的研究同样具有一定意义。 相似文献
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陕西紫阳高桥地区早奥陶世微古植物群及其地层意义 总被引：1，自引：0，他引：1
陕西紫阳高桥地区的奥陶系为浅变质的笔石页岩。该区皮家坝剖面的下奥陶统中产丰富的微古植物,共计45属、200余种,其中有新种17个,新变种2个。自下而上分为三个组合带,组合Ⅰ,产于高桥组,以Micrhystridium—Buedingiisphaeridium 为代表,其时代相当于Tremadocian 晚期。组合Ⅱ,产于权河组之下部,以Baltisphaeridium—Peteinosphaeridium—Polygonium 为代表,其时代大致为早Arenigian。组合Ⅲ,产于权河口组的中部。根据其组合特征及所含的笔石化石,将高桥组与云南汤池组对比,将权河口组与红石崖及宜昌大湾组对比。该区微古植物群与波罗的古浮游生物区的相似。 相似文献
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陕西紫阳高桥地区早奥陶世微古植物群及其地层意义 总被引：3，自引：0，他引：3
陕西紫阳高桥地区的奥陶系为浅变质的笔石页岩。该区皮家坝剖面的下奥陶统中产丰富的微古植物,共计45属、200余种,其中有新种17个,新变种2个。自下而上分为三个组合带:组合Ⅰ,产于高桥组,以Micrhystridium—Buedingiisphaeridium为代表,其时代相当于Tremadocian晚期。组合Ⅱ,产于权河组之下部,以Baltisphaeridium—Peteinosphaeridium—Polygonium为代表,其时代大致为早Arenigian。组合Ⅲ,产于权河口组的中部。根据其组合特征及所含的笔石化石,将高桥组与云南汤池组对比,将权河口组与红石崖及宜昌大湾组对比。该区微古植物群与波罗的古浮游生物区的相似。 相似文献
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海相红层是红层研究的一个重要方向,在前人地层学、古生物学等资料基础上,笔者在鄂尔多斯周缘露头区针对奥陶纪海相红层进行了专门研究,从中识别出7套奥陶纪海相红层。借助于对应地层中已报道的笔石、三叶虫、珊瑚等不同化石类别的特征分子、典型化石带或化石组合,基本确定了这7套海相红层的形成时代:自下而上分别为特马豆克期、弗洛期晚期(也许包括大坪期早期)、大坪期、达瑞威尔期、桑比期、凯迪期早期和凯迪期晚期。建立了鄂尔多斯周缘奥陶纪海相红层对比表,分析了奥陶纪海相红层形成环境和古地理分布情况。 相似文献
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湖北京山-钟祥一带的下奥陶统特征与毗邻的峡东及随南地区存在明显差异,在此开展了岩石地层和生物地层研究对比有助于更好地了解扬子北缘早奥陶世的古地理特征及演化.通过详细的剖面测制和地层对比研究,将钟祥-京山地区下奥陶统自下而上分为娄山关组、温峡口组（新建）、钟祥组（新建）和大湾组.新建的温峡口组以竹叶状灰岩、鲕粒灰岩、生物碎屑灰岩为主,属于台地边缘浅滩-浅水陆棚相沉积.根据温峡口组中所产的腹足、腕足和头足类化石,认为其沉积时代为特马豆克期中-晚期至弗洛期早期.钟祥组为灰色-灰黑色笔石页岩夹薄层粉砂岩及少量生物碎屑灰岩透镜体,产丰富的腕足、三叶虫、海百合茎、笔石、头足类等生物化石,属于深水陆棚区沉积,其地质时代为早奥陶世弗洛期.通过区域地层对比,温峡口组与峡东南津关组、分乡组、红花园组和随南高家湾组底部层位相当,而钟祥组则与峡东大湾组下段的下部和随南高家湾组中-上部可以对比. 相似文献
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浙江临安板桥早奥陶世牙形刺新材料及其意义 总被引：1，自引：0，他引：1
在浙江临安板桥早奥陶世的留下组、施家头组和荆山组中发现较丰富的牙形刺动物群,自下而上建立Cordylodus angulatus带、Chosonodina herfurthi带、Paltodus deltifer带、Paroistodus proteus带和Prioniodus elegans带等5个牙形刺带,均属于早奥陶世。研究表明,临安板桥一带的早奥陶世碳酸盐岩地层时代局限于早奥陶世特马豆克期—弗洛期,与上覆中奥陶世达瑞威尔期硅质泥岩呈假整合接触关系,其间缺失弗洛晚期—达瑞威尔早期沉积。这一发现对该地区的地层划分对比和古地理研究具有重要意义。 相似文献
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湖北宜昌和南漳奥陶系大湾组笔石生物地层 总被引：4，自引：4，他引：0
根据宜昌陈家河剖面大湾组的笔石标本,确立笔石序列自下而上为:Didymograptellus eobifidus带、Corymbograptus deflexus带和Azygograptus suecicus带(大湾组下段),Exigraptus clavus带和Undulogr aptusaustrodentatus带(大湾组上段)。对湖北南漳的全家湾和李家湾两剖面的大湾组进行了详细采集测量,其中全家湾剖面大湾组下段自下而上识别出D.eobifidus带、C.deflexus带和A.suecicus带;李家湾剖面大湾组下段自下而上识别出D.eobifidus带和A.suecicus带,证实南漳大湾组的底界与宜昌地区基本一致。 相似文献
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湖北宜昌黄花场中/下奥陶统界线附近几丁虫组合及其地层学意义 总被引：4，自引：1，他引：4
对宜昌黄花场大湾组下段牙形石 Oepikodus evae带至 Baltoniodus triangularis带系统采集与分析几丁虫样品 ,共发现几丁虫 6属 12种 ,其中包括 1个相似种、1个未定种 ,它们是 Conochitina raymondii,C.ordinaria,C.primitiva,C.langei,C.brevis,C.poumoti,C.decipiens,Belonechitina cf.micracantha,L agenochitina esthoni-ca,L.sp.,Eremochitina baculata和 Cyathochitina dispar等。根据上述几丁虫的地质和地理分布特征 ,自下而上可划分为 Conochitina langei带和 Eremochitina baculata带 ,讨论并指出了他们与相关笔石、牙形石生物带的关系 相似文献
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Svend Stouge David A. T. Harper George D. Sevastopulo Darren O'Mahony John Murray 《Geological Journal》2016,51(4):584-599
The Middle Ordovician Rosroe Formation consists of some 1350 m of coarse, mainly siliciclastic to volcaniclastic sedimentary rocks, deposited in a submarine fan environment, and is restricted to the southern limb of the South Mayo Trough, western Ireland. Discrete allochthonous blocks, reaching 5 m in size, are present in the formation at several localities. Conodonts recovered from these blocks, collected from two separate locations, are of late Early and mid Mid Ordovician age. The conodonts have high conodont‐alteration indices (CAI 5) indicative of temperatures as high as 300o to max. 480 °C; some found in the Lough Nafooey area have abnormally high indices (CAI 6), which correspond to temperatures of about 360o to max. 550 °C. The oldest fauna is dominated by Periodon aff. aculeatus and characterized by Oepikodus evae typical of the Oepikodus evae Zone (Floian Stage; Stage Slices Fl2–3, Lower Ordovician). The younger conodont assemblage, characterized by Periodon macrodentatus associated with Oistodella pulchra, is referred to the P. macrodentatus conodont Biozone (lower Darriwilian; Stage Slices Dw1–2). The Rosroe conodont assemblages are of Laurentian affinity; comparable faunas are well known from several locations along the east to south‐eastern platform margin of Laurentia and the Notre Dame subzone of central Newfoundland, Canada. The faunal composition from the limestone blocks suggests a shelf edge to slope (or fringing carbonate) setting. The faunal assemblages are coeval with, respectively, the Tourmakeady Formation (Floian–Dapingian) and Srah Formation (Darriwilian) in the Tourmakeady Volcanic Group in the eastern part of the South Mayo Trough and probably are derived from the same or similar laterally equivalent short‐lived carbonate successions that accumulated at offshore ‘peri‐Laurentian’ islands, close to and along the Laurentian margin. During collapse of the carbonate system in the late Mid Ordovician, the blocks were transported down a steep slope and into deep‐water by debris flows, mixing with other rock types now found in the coarse polymict clastics of the Rosroe Formation. The faunas fill the stratigraphical ‘gap’ between the Lower Ordovician Lough Nafooey Volcanic Group and the upper Middle Ordovician Rosroe Formation in the South Mayo Trough and represent a brief interval conducive to carbonate accumulation in an otherwise siliciclastic‐ and volcaniclastic‐dominated sedimentary environment. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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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。 相似文献
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L. S. Normore Y. Y. Zhen L. M. Dent J. L. Crowley I. G. Percival M. T. D. Wingate 《Australian Journal of Earth Sciences》2018,65(1):61-73
A continuously cored section of more than 300 m through the Nambeet Formation and the basal part of the conformably overlying Willara Formation in the Olympic 1 petroleum well, drilled in the Canning Basin of northern Western Australia, yields valuable information that increases by more than 40% the number of precise isotopic ages available to constrain the Ordovician Period. New CA-IDTIMS U–Pb zircon ages for seven bentonite layers in the Olympic 1 core are integrated into a new conodont biostratigraphic framework for the Early Ordovician comprising four biozones recognised in this well. The weighted mean U–Pb dates range from 479.37 ± 0.16 Ma within the late Tremadocian Paroistodus proteus conodont Biozone, to 470.18 ± 0.13 Ma near the boundary between the Floian and Dapingian stages within the Jumudontus gananda conodont Biozone. The intervening Prioniodus oepiki–Serratognathus bilobatus conodont Biozone (early Floian) and succeeding Oepikodus communis conodont Biozone (middle Floian) are similarly well constrained by isotopic dates centred on ca 477 Ma for the early Floian and by three ages of 473–471 Ma for the middle Floian. The seven new isotopic dates significantly increase the precision of dating for the Early Ordovician, where previously only two ages with limited or imprecise biostratigraphic control were known globally. 相似文献
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目前浙赣三山地区“金钉子”尚无精确的同位素年龄数据.基于钾质斑脱岩SHRIMP锆石U-Pb测试,三山地区早-中奥陶世宁国组Azygograptus suecicus带中部、Exigraptus clavus带底部、Acrograptus ellesae带中部的同位素年龄分别为482.9±6.1 Ma、477.6±8.3 Ma和467.0±4.4 Ma,为华南地区中奥陶世大坪阶和达瑞威尔阶底界的全球界线层型（GSSP）开展地层对比提供了精确的同位素年代学依据.结合生物带对比,大致将浙西地区早-中奥陶世普遍存在的地层缺失事件的发生时限界定于482.9~477.6 Ma之间,即杭州-嘉兴台地缺失牙形刺Oepikodus evae带-Lenodus anticariabilis带（或笔石Azygograptus suecicus带-Acrograptus ellesae带）地层,其代表了郁南运动在浙西地区的具体表现,拉开了华南地区早古生代构造运动的序幕,也可能是欧洲加里东造山过程中亨伯运动和塔康运动的远程响应. 相似文献