新疆塔里木盆地西北缘晚奥陶世疑源类

新疆塔里木盆地西北缘阿克苏和柯坪地区达瑞威尔期末期至凯迪期中期地层发育良好,大湾西沟剖面、四十场剖面和铁热克阿瓦提剖面地层保存良好的疑源类组合。该组合包括20属36种疑源类,以棘刺类、光球类和梭形类占优势。塔里木盆地西北缘疑源类组合与国内、外同期组合对比表明晚奥陶世疑源类古地理分区性减弱,部分疑源类分子分布仅限于晚奥陶世,且古地理分布广泛,具有生物地层学对比的潜力。新疆塔里木盆地西北缘数条剖面疑源类组成和多样性变化的不同可能与小环境的差异有关。本研究中疑源类属种组成及多样性变化趋势和柯坪地区海平面变化一致,反映了萨尔干组到其浪组下部有一次海侵过程。     

滇东南奥陶纪三叶虫的地层记录

滇东南位于奥陶纪扬子区的西南边缘,濒临古陆,水体较浅,沉积物中陆源碎屑丰富,而且因地壳升降运动幅度相对较大,导致了巨大的地层沉积厚度,仅含三叶虫地层就厚达385—2 080m,是我国奥陶纪三叶虫研究的空白地区。文中首次记述该地区下奥陶统下木都底组(下特马豆克阶)、独树柯组(上特马豆克阶)、闪片山组(特马豆克阶顶部—弗洛阶底部)、下奥陶统(弗洛阶)—中奥陶统上部(达瑞威尔阶下部)老寨组和中奥陶统顶部(达瑞威尔阶上部)—上奥陶统底部(桑比阶底部)冷水沟组的三叶虫序列,并系统描述了有关三叶虫,共计10科,15属,18种。其中特马豆克阶—达瑞威尔阶下部的三叶虫与鄂西和黔北所产最为相似,与川南及渝南一带同期分子也有关联,而达瑞威尔阶上部—桑比阶底部的分子则与黔北十字铺组动物群并无差异,代表当时滇黔隆起边缘的浅水动物群。对Mansuy(1920)描述的越南北部下奥陶统下部Dong Son组的三叶虫作了厘定,但由于有关材料保存太差、种级单元的鉴定特征模棱两可,目前暂无法得以在区内沿用。     

浙江常山黄泥塘全球层型剖面的中奥陶世疑源类

浙江常山黄泥塘剖面在1996-1997年被国际奥陶系分会和国际地质科学联合会(IUGS)确立为全球中奥陶统达瑞威尔阶(Dariwillian)层型剖面,从该剖面宁国组Azygograptus suectcus-Exigraptus clavus笔石带至Undulograptus sinicus笔石亚带下部的页岩及灰岩中获得丰富的,保存不很好的疑源类化石,它们包含26个形态属,41个已知种和12个未定名种.该宁国组疑源类组合极少有环冈瓦纳古陆的“冷水“类型,根据疑源类类型在地层柱的首次出现,可划分两个与Azygograptus suecicus和Undulograptus austrodentatus笔石带相吻合的疑源类生物地层单元,结合中国南方在奥陶纪的古地理位置加以讨论,当前疑源类组合表明,中奥陶世环冈瓦纳古陆的“冷水“洋流至下扬子区已很微弱.     

滇东北奥陶纪三叶虫的地层分布

详细讨论滇东北奥陶纪的岩石地层和动物群特征,初步建立区内的三叶虫地层序列,据此可靠确定各有关岩组的时代。该地区除普遍缺失早奥陶世早期的沉积外,依次发育了红花园组(特马豆克末期—弗洛初期),湄潭组(弗洛期—达瑞威尔初期),风洞岗组(达瑞威尔早—晚期),十字铺组(达瑞威尔末期—桑比早期)、宝塔组(桑比晚期—凯迪早期),盐津组(晚凯迪早期)、五峰组(晚凯迪晚期)及观音桥组(赫南特期),岩相与黔北的相应岩组可作大致对比,而三叶虫动物群的组成和序列则大体与当时同属扬子陆块西部边缘的沉积区包括滇东、滇东南、黔北、川中、重庆、陕南及安徽和县等地区相似。共记述本区奥陶纪三叶虫计19属27种,分属14科。并对其中的一个新种Hungioides yanjinensis sp.nov.以及两个未命名的新种Abulbaspis sp.nov.和Plaesiacomiasp.nov.作系统描述。Abulbaspis过去仅报道于华北和哈萨克斯坦地区的达瑞威尔阶,而在本地区则产于桑比阶上部—凯迪阶下部;Plaesiacomia广泛分布于达瑞威尔阶—桑比阶西泛冈瓦纳地区,在滇东北的发现不但将该属的分布区域扩大到了东泛冈瓦纳地区,而且因其产出于大坪中期的层段,表明该属可能起源于东泛冈瓦纳,尔后才向西迁移的;这两属在扬子区的首次发现,对于进一步研究奥陶纪不同区块间的三叶虫动物群的扩散和交流具有重要意义。     

滇东北奥陶纪三叶虫的地层分布北大核心CSCD

详细讨论滇东北奥陶纪的岩石地层和动物群特征,初步建立区内的三叶虫地层序列,据此可靠确定各有关岩组的时代。该地区除普遍缺失早奥陶世早期的沉积外,依次发育了红花园组(特马豆克末期—弗洛初期),湄潭组(弗洛期—达瑞威尔初期),风洞岗组(达瑞威尔早—晚期),十字铺组(达瑞威尔末期—桑比早期)、宝塔组(桑比晚期—凯迪早期),盐津组(晚凯迪早期)、五峰组(晚凯迪晚期)及观音桥组(赫南特期),岩相与黔北的相应岩组可作大致对比,而三叶虫动物群的组成和序列则大体与当时同属扬子陆块西部边缘的沉积区包括滇东、滇东南、黔北、川中、重庆、陕南及安徽和县等地区相似。共记述本区奥陶纪三叶虫计19属27种,分属14科。并对其中的一个新种Hungioides yanjinensis sp.nov.以及两个未命名的新种Abulbaspis sp.nov.和Plaesiacomiasp.nov.作系统描述。Abulbaspis过去仅报道于华北和哈萨克斯坦地区的达瑞威尔阶,而在本地区则产于桑比阶上部—凯迪阶下部;Plaesiacomia广泛分布于达瑞威尔阶—桑比阶西泛冈瓦纳地区,在滇东北的发现不但将该属的分布区域扩大到了东泛冈瓦纳地区,而且因其产出于大坪中期的层段,表明该属可能起源于东泛冈瓦纳,尔后才向西迁移的;这两属在扬子区的首次发现,对于进一步研究奥陶纪不同区块间的三叶虫动物群的扩散和交流具有重要意义。     

陕西宁强—四川广元地区奥陶系“涧草沟组”和宝塔组牙形刺生物地层研究之新进展

开展陕西宁强范家沟、赵家坝和四川广元谭家沟3条剖面奥陶系牙形刺生物地层研究。在宁强地区"涧草沟组"发现了凯迪阶中部的Protopanderodus insculptus生物带,它相当于湖北宜昌地区上奥陶统临湘组之同名带;宝塔组由上而下可划分为Hamarodus brevirameus,Baltoniodus variabilis,Yangtzeplacognathus jianyeensis和Y.foliaceus等牙形刺带,属达瑞威尔阶上部至凯迪阶下部,可与湖北宜昌地区中-上奥陶统牯牛潭组顶部至宝塔组的同名带对比;广元地区宝塔组则见Baltoniodus variabilis和Yangtzeplacognathus jianyeensis生物带,属达瑞威尔阶顶部至桑比阶,可与湖北宜昌地区庙坡组或南京地区大田坝组的同名带对比。上述发现改变了先前的认识:陕西宁强地区宝塔组划分为Hamarodus europaeus和Eoplacognathus jianyeensis两牙形刺带,与湖北宜昌地区庙坡组和宝塔组地层相当;四川广元地区宝塔组归入Pygodus serra-Eoplacognathus foliaceus牙形刺带,与湖北宜昌地区牯牛潭组对比。邱洪荣(1989)建立的4个新种可能是一些老属种不同形态的组成分子,因此在本文属种描述部分把它们分别列入相应属种的同义名录。     

新疆巴楚中-晚奥陶世牙形刺研究的新进展

新疆巴楚新测一间房剖面分析出牙形刺24属47种。以带分子首现为标志,该剖面中上奥陶统自上而下可划分出8个牙形刺带。其中,恰尔巴克组3个带:Baltoniodusalobatus,Prioniodusvariabilis,Pygodusanserinus;一间房组3个带:Eoplacognathuscrassus,Lenodus(Amorphognathus)variabilis,Microzarkodinaparva;鹰山组2个带:Paroistoduscf.originalis;PteracontiodusexilisScolopodusbicostatus组合带。这些牙形刺带完全可与我国浙江常山黄泥塘金钉子剖面以及华南达瑞威尔阶及其上下的牙形刺带进行对比,证实一间房组几乎与达瑞威尔阶完全相当;恰尔巴克组可与华南庙坡阶对比。据牙形刺带有缺失的认识,结合地震、物探资料认为巴楚塔河阿克库勒等凸起地区,奥陶系中、上统之间有间断存在。     

贵州黄花冲下奥陶统湄潭组疑源类

对贵州黄花冲奥陶系湄潭组Azygograptus suecicus带疑源类组合研究表明,该组合可以与扬子区陕南、川东南、黔北、黔南、湘西、鄂西等地同期组合对比,并根据特征分子产出判别该组合应划归环冈瓦纳疑源类生物地理区。鄂西宜昌大湾组疑源类组合与黄花冲湄潭组疑源类组合的差异系环境因素所致。     

滇东奥陶纪三叶虫序列

滇东属于奥陶纪扬子地层区西缘的重要组成部分,本文系统描述该地区奥陶系8个层位的三叶虫,共计10科17属18种(其中包括1个新属种,即Daketia spinata gen.and sp.nov.),初步建立区内的三叶虫动物群地层序列,据此可靠确定有关地层的时代,包括:汤池组(特马豆克晚期—弗洛最早期)、红石崖组(弗洛早期—达瑞威尔最早期)、下巧家组(大坪期—达瑞威尔中期)、上巧家组(达瑞威尔晚期—桑比早期)。典型的红石崖组发育于滇东南部的昆明和宜良一带,其上部为含二叶石砂岩,假整合于泥盆纪石英砂岩之下,但是这部分层段在武定-寻甸一线以北地区并未见及,却沉积了一套砂岩、页岩、泥灰岩和白云质灰岩(即下巧家组);按区内地层发育的时空分布来判断,Zhou等(2011)提出的下巧家组和红石崖组上部应系同期异相沉积的观点得到证实。各地层单元的三叶虫动物群分异度低且均为扬子陆块浅水区的常见地方性分子(包括原来记录于越南北部的Vietnamia douvillei(Mansuy)),指示浅内陆棚环境。     

滇东奥陶纪三叶虫序列北大核心CSCD

滇东属于奥陶纪扬子地层区西缘的重要组成部分,本文系统描述该地区奥陶系8个层位的三叶虫,共计10科17属18种(其中包括1个新属种,即Daketia spinata gen.and sp.nov.),初步建立区内的三叶虫动物群地层序列,据此可靠确定有关地层的时代,包括:汤池组(特马豆克晚期—弗洛最早期)、红石崖组(弗洛早期—达瑞威尔最早期)、下巧家组(大坪期—达瑞威尔中期)、上巧家组(达瑞威尔晚期—桑比早期)。典型的红石崖组发育于滇东南部的昆明和宜良一带,其上部为含二叶石砂岩,假整合于泥盆纪石英砂岩之下,但是这部分层段在武定-寻甸一线以北地区并未见及,却沉积了一套砂岩、页岩、泥灰岩和白云质灰岩(即下巧家组);按区内地层发育的时空分布来判断,Zhou等(2011)提出的下巧家组和红石崖组上部应系同期异相沉积的观点得到证实。各地层单元的三叶虫动物群分异度低且均为扬子陆块浅水区的常见地方性分子(包括原来记录于越南北部的Vietnamia douvillei(Mansuy)),指示浅内陆棚环境。     

黔东早—中寒武世凯里组疑源类组合及其界线意义

通过对台江八郎和丹寨两条剖面凯里组中疑源类化石的分析,研究,台江剖面产疑源类化石有17属35各（12未定种）,其中以Leiosphaeridia,Synsphareidium,Cymatiosphaera,Pterospermella最为丰富,可划分为3个组合,即Cymatiosphaera cf.cristata-Fimbriaglomerella memebrancea组合,Cristallinium-Micrhystridium-Pterospermella组合和Dictyotidium-Granomarginata组合,丹寨平寨剖面凯里组所产疑源类化石有：13属21种（5未定种）,同样划分为3个组合,即Leiosphaeridia-Tasmanites组合,Retisphaeridium-Micrhystridium tentatium组合和Baltisphaeridium-Bubomorpha hunjiangensis组合,本文对两条剖面中的凝源类化石的组成,相对含量做了详细的统计,发现在八郎剖面9－2层和平寨剖面3层疑源类的丰度,分异度开始发生明显的变化,表现由早寒武世向中寒武世疑源类组合面貌的转变,这一疑源类转变层位正好是与三叶虫划分的中,下寒武统界线的层位位置相一致,这充分表明疑源类化石可作为划分中,下寒武统的极有价值的微体生物化石证据。     

峡东地区上奥陶统高庙坡组球节子类及其它多节类三叶虫

系统描述湖北宜昌和秭归新滩晚奥陶世庙坡组球接子类及多节类三叶虫动物群中的１４种,分属于９属、７科、。根据化石保存状态、挤压变形以及个体发育特征,对前人所报道的产于本组的有关三叶早作了大量归并、转移和重新厘定,新的材料支持解释Telephiana longicephala的性双形现象。Ａtractopyge系首次在庙坡组中发现,以往它在三峡地区只见于临湘组。文中还将新疆的一个保留命名种Ｌonchodomas cf.yohi重新命名为Ｌonchodomas zhangi sp.nov.。     

湖北宜昌黄花场早奥陶世疑源类的新类型

该文报道了湖北宜昌黄花场下奥陶统大湾组下段的疑源类（海洋微体浮游植物化石）新类型,描述和建立３新属：Ｐａｐｉｌｌｉｆｅｒｕｍｇｅｎ．ｎｏｖ．,１ｇｅｎ．ｎｏｖ．和Ｙｉｃｈａｎｇｉａｇｅｎ．ｎｏｖ．;２新种：Ｐａｐｉｌｌｉｆｅｒｕｍｉｒｒｅｇｕｌａｒｅｇｅｎ。ｅｔｓｐ．ｎｏｖ．,Ｙｉｃｈａｎｇｉａｂｉｐｏｒｏｓａｇｅｎ;ｅｔｓｐ。ｎｏｖ。及重新修改和组合的３属、种：Ｐａｐｉｌｌｉｆｅｒｕｍｒｈａｂｄｏｃｌａｄｉｕｍ（Ｌｕ）ｃｏｍｂ．ｅｔｅｍｅｎｄ．ｎｏｖ．,Ｐ。ｓｔｒｉａｔｕｍ（Ｌｕ）ｃｏｍｂ．ｅｔｅｍｅｎｄ。ｎｏｖ。和Ｓｔｅｌｏｍｏｒｐｈａｅｒｃｈｕｎｅｎｓｉｓ（Ｆａｎｇ）ｃｏｍｂ;ｅｔｅｍｅｎｄ．ｎｏｖ．这些疑源类新类型目前仅见于我国西南的部分地区的早奥陶世地层。它们为探讨早奥陶世海洋微体浮游植物的区域分布及扬子地台的古地理位置,提供了重要的证据．     

The oldest known occurrence of the Foliomena fauna in the uppermost Darriwilian (Middle Ordovician) of South China

The oldest Foliomena fauna was, until now, known from the middle–upper Miaopo Formation (Nemagraptus gracilis Biozone, lower Sandbian, basal Upper Ordovician) of South China. In this study, the oldest record of the fauna is set back to the latest Darriwilian (upper Hustedograptus teretiusculus Biozone), represented by Foliomena jielingensis and some typical constituents of the Foliomena fauna from the basal Miaopo Formation at Jieling, northern Yichang, western Hubei Province, central China. The Miaopo Formation is characterized by its organic‐rich dark‐grey shale facies, unique in its localized distribution on the Yangtze Platform, and distinguished by its rich and diverse benthic and graptolitic faunas. This suggests an origin of the Foliomena fauna in periodically oxygen‐starved local depressions on the Yangtze Platform during the Middle–Late Ordovician transition.     

湖北宜昌地区下-中奥陶统界线疑源类生物地层学意义

根据牙形类Baltoniodus? triangularis的首现,中奥陶统和大坪阶底界已界定于湖北宜昌黄花场剖面大湾组底界之上10.57m.对黄花场剖面以及邻近的大坪剖面大湾组疑源类研究表明,某些疑源类属种具有生物地层学意义,其首现可用于识别奥陶系下/中统界线.     

Upper Ordovician microphytoplankton of the Bill's Creek Shale and Stonington Formation,Upper Peninsula of Michigan,U.S.A.: Biostratigraphy and paleogeographic significance

An abundant, diverse, and well-preserved organic-walled microphytoplankton assemblage is described from the Upper Ordovician Bill's Creek Shale and the lower Stonington Formation (Bay de Noc Member) in the Upper Peninsula of Michigan, U.S.A. Based on graptolite and conodont evidence, the Bill's Creek Shale and Stonington Formation are Richmondian (=Ashgill) in age. The assemblage is dominated by acritarchs, which comprise 29 species (including the enigmatic palynomorph Gloeocapsomorpha prisca) assigned to 20 genera. The prasinophyte phycomata are represented by undifferentiated species of Leiosphaeridia and Tasmanites. In addition, chitinozoans are abundant, and scolecodonts and graptolite fragments are common. Paleontologic-palynologic and sedimentologic evidence indicates that the Bill's Creek Shale was deposited in a low-energy, shallow, nearshore marine environment. The overlying Bay de Noc Member of the Stonington Formation also accumulated in a low-energy, normal marine environment, but in a more offshore, somewhat deeper water setting. Both formations experienced minor transgressive and regressive episodes as indicated by fluctuations in the composition of the palynoflora. The combined Bill's Creek/Stonington acritarch assemblage closely resembles those described from the Richmondian-aged Maquoketa Shale (Missouri and Kansas), Sylvan Shale (Oklahoma), and Vauréal Formation (Anticosti Island, Québec, Canada). The overall composition of the acritarch assemblage from these four formations reflects a distinctive, recognizably Laurentian character. Nonetheless, many of the Bill's Creek/Stonington acritarchs have been reported from Upper Ordovician localities elsewhere, providing additional evidence for Late Ordovician cosmopolitanism of the marine microphytoplankton community. Additionally, the restricted stratigraphic range of many of the taxa further enhances their biostratigraphic application, both regionally and globally, and reaffirms the Richmondian (=Ashgill) age of the Bill's Creek Shale and Stonington Formation.     

The Micropaleoflora Features from Middle Carbonate Rock Formation of Jiezha Group in South Qinghai

The micropaleoflora from the Middle Carbonate Rock Formation of Jiezha Group has been firstly studied in this paper. The abundance sporopollen and variform acritarch characterizing the formation contain 62 genera and 91 species, in which 20 gen. and 31 sp. belong to sporopollen, 42 gen and 60 sp. acritarch. Among them one is affinis, twelve conformis and five species, in addition, four species indeterminata. The sporopollen assemblage is consisted of the dominant gymnospermous pollen of 49.0% in the amount, spore 18.8% and acritarch 32.2%. In detail, the spore is mainly made from Punctatisporites, Apiculatisporis, Marattisporites, the pollen Pinaceae, Ovalipollis, Cycadopites and a few Chordasporites, Taeniaesporites, the acritarch Hystrichosphaeridium, Micrhystridiura, Favososphaeridium, besides Leiofusa Quadratimorpha, Scolecodonts, Taenitum, Lignum and so on. The geological time is middle upper Triassic. The Carbonate Rock Formation is composed of a suite of the epicontinental sedimentary strata being 1303 m thickness and formed in the stably olepositional enviroment. The region should, then, lie in the shore of Paleomediterranean sea or near the geosyncline round the Pacific. Based on the abundance gymnospermous spore fron Jiezha Group, the climate at that time should be humid torrid or subtorrid zone marine.     

贵州三都地区阿伦尼克期疑源类的发现及其意义

本文首报报道了发现贵州三都地区同高组下段的疑源类化石,属种丰富,保存完好,它们多见于阿伦尼克期至兰维尔期,其中有些分子仅限一阿伦尼克期,根据组合中出现较多的Ｓｔｒｉａｔｏｔｈｅｃａ,Ｃｏｒｙｐｈｉｄｉｕｍ和Ａｒｂｕｓｃｕｌｉｄｉｕｍ等,认为本区可能属地中海疑源类生物区,详细研究这些化石对认识疑源类组合与笔石带的关系有重要意义。     

BASAL CAMBRIAN MICROFOSSILS FROM THE YURTUS AND XISHANBLAQ FORMATIONS (TARIM, NORTH-WEST CHINA): SYSTEMATIC REVISION AND BIOSTRATIGRAPHIC CORRELATION OF MICRHYSTRIDIUM-LIKE ACRITARCHS

Abstract:  Micrhystridium -like acritarchs are widely distributed in basal Cambrian cherts and phosphorites in South China. This paper describes similar acritarchs from the basal Cambrian Yurtus and Xishanblaq formations in Tarim, north-west China. The taxonomy of these acritarchs is revised. The basal Cambrian acritarch assemblage in Tarim and South China is characterized by three genera: Asteridium Moczydłowska, Heliosphaeridium Moczydłowska and Comasphaeridium Staplin, Jansonius and Pocock. This assemblage is named the Asteridium - Heliosphaeridium - Comasphaeridium (AHC) acritarch assemblage. In both South China and Tarim, the AHC acritarch assemblage is associated with the tubular microfossil Megathrix longus Yin L. and the small shelly fossil Kaiyangites novilis Qian and Yin G. This assemblage also occurs in the Lower Tal Formation in the Lesser Himalaya. Correlation with small shelly fossil (SSF) assemblages indicates that the AHC assemblage is restricted to the Meishucunian Stage, and possibly to the lower Meishucunian ( Anabarites trisulcatus - Protohertzina anabarica and Siphogonuchites triangularis - Paragloborilus subglobosus SSF assemblages). The AHC assemblage is broadly similar to the Asteridium tornatum - Comasphaeridium velvetum (acritarch) Zone in the East European Platform, which is considered to be Nemakit-Daldynian (and possibly Tommotian) in age.