早寒武世疑源类的古生物地理学意义

根据早寒武世疑源类在全球的古地理分布，并参考古地磁和动物化石等方面的资料，进行了早寒武世疑源类的古地理分区。结果表明：早寒武世在全球范围内可分为2个疑源类古地理大区，即波罗的海－北美－亚、澳大区和地中海大区；我国西南地区早寒武区筇竹寺期，可根据疑源类分为两个生态区，即扬子区和江南区。这一研究结果为今后各区生态结构分析，提供了重要基础资料。     

四川峨眉高桥震旦系——寒武系界线

四川峨眉高桥震旦系—寒武系界线剖面构造简单,沉积连续,化石丰富,是我国研究震旦系与寒武系界线重要剖面之一。本文系统地介绍了峨眉山地区震旦系—寒武系的研究历史,剖面详细分层及岩性和生物特征。论述了本区晚震旦世至早寒武世初期沉积环境的变迁、生物演化及震旦系—寒武系界线划分。本文以首次多门类带壳动物的大量出现作为划分震旦系与寒武系界线的主要依据。寒武系的下界划分在麦地坪组下部以小壳动物Anabarites—Circotheca为代表的化石组合的底界上,并与国内外相当时代的地层及界线进行了对比。     

贵州台江早寒武世台江动物群的发现及意义

贵州台江八郎凯里组剖面中下部中、下寒武统界线之下厚达１５米左右的粉砂质泥岩、页岩中存在着一个类似凯里动物群的台江动物群,由８个门类３９个属组成,核心为蠕形动物,三叶虫数量很多。形成于内陆棚浅海环境。时代为早寒武世末期,介于著名的早寒武世早期澄江动物群和中寒武世早期凯里动物群之间,对于早期后生动物的演化研究具有重要的意义。     

贵州台江中寒武世凯里组发现稀有棘皮动物化石

贵州凯里台江屯州中寒武世早期地层凯里组,主要由泥岩组成,发育良好,化石主要为底栖的扬子型,也混有游泳的三叶虫,属江南型和扬子型之间的过渡类型地层(周志毅等,1979,1980)。     

上扬子地区震旦—寒武纪磷块岩岩石学特征及成因分析

采用古地理、岩石学、有机地球化学、地球化学分析的方法,对上扬子区晚震旦陡山沱组和早寒武牛蹄塘组不同类型的磷块岩进行了研究。认为早寒武世早期古陆遭受风化,被剥蚀下来的产物成为潮坪型磷块岩的主要磷质来源,在碳酸盐岩台地发生的热点活动和上升洋流从盆底深部带来的磷质,共同作为台地型磷块岩的磷源,盆地型磷块岩的磷质同样是由热点活动和上升流携带至缺氧的沉积环境中,通过藻类或微生物的富集作用成岩,并保留了较高的有机碳含量。     

中扬子地区下寒武统烃源岩横向分布及主控因素分析

基于前人研究资料和野外露头剖面详细观测及样品实测数据,讨论了中扬子地区下寒武统烃源岩的横向分布特征,探讨了烃源岩横向分布的主控因素.研究认为:中扬子地区下寒武统烃源岩围绕中扬子碳酸盐台地呈环状分布;台地内没有烃源岩发育,向洋一侧烃源岩逐渐加厚.研究区下寒武统烃源岩的分布受控于早寒武世早期盆地原型的分布,烃源岩的发育受沉积相控制.烃源岩所发育的相带均为陆棚边缘盆地相,早寒武世沧浪浦期—龙王庙期的浅海陆棚相、滨浅海相、台缘滩相、台缘斜坡相、局限台地相等沉积相带的碎屑岩、碳酸盐岩有机质含量均较低,烃源岩发育极差.     

合肥盆地逆掩冲断带地质-地球物理综合解释及其大地构造属性

在大量地震剖面综合解释的基础上 ,提出华北板块与北淮阳晚加里东 -早海西期褶皱带的界线应在六安断裂 ,肥中断裂是华北陆壳型基底与其过渡壳型基底的大致分界。首次发现合肥盆地侏罗系之下存在以青白口系刘老碑组泥质岩为主滑脱层的印支期形成的由南向北滑脱冲断、主要卷入华北地台及其被动陆缘上元古 -古生界的完整冲断体系 ,并认为侏罗纪盆地为再生前陆盆地 ,编制了前侏罗系基岩地质图 ,为研究华北、大别及扬子三大块体的相互关系提供了新资料     

黔北磷块岩型铀矿床成因——以703矿床为例

采用等离子体质谱(ICP-MS)分析研究了矿床微量元素和稀土元素特征。结果表明,矿床成矿物质主要来源于上地壳;早寒武世早期的热液喷流沉积作用与铀成矿有关。矿床成因为早寒武世早期,局限海盆边缘的凝灰质陆源物遭剥蚀淋滤,其中的铀被大量带入海洋,在缺氧的还原性环境下,铀以磷块岩和有机质为载体,通过热水沉积作与磷和有机质共同沉淀,形成同生沉积型磷块岩型铀矿床。     

贵州福泉道坪地区寒武系三叶虫序列

早寒武世早中期,福泉道坪地区位于扬子沉积区东缘,以过渡区为邻(卢衍豪等,1974;周志毅等,1979、1980),处于水下隆起状态(周志毅等,1979),出现一些黔中地区少见的三叶虫。中寒武统石冷水期三叶虫也比较丰富,并有鄂尔多斯虫科三叶虫的出现。道坪地区寒武系三叶虫序列的研究,补充了黔中地区乃至扬子地区三叶虫序列。在南京地质古生物研究所三叶虫组及贵州区域地质测量大队尹恭正的帮助下,经作者研究,福泉道坪地区寒武系石冷水组以下的三叶虫序列如下:     

四川西南部震旦系研究 四川西南部震旦系的岩性特征及沉积环境

前震旦纪末期扬子准地台基底基本形成,但在早震旦世早期,地壳仍然处于活动状态,火山作用极为频繁,导致地形强烈分异、高差悬殊的大陆环境,包括剥蚀山地、断陷谷地、河流、湖泊、冰川及火山等地貌单位。震旦系下统以各种碎屑岩为主的沉积组     

Sponge spicules in phosphorites of the Early Cambrian Gezhongwu Formation, Zhijin, Guizhou

Phosphorites occurring at the bottom of the Cambrian system contain abundant small shelly fossils, which are the product of the first episode of life explosion in the Cambrian. It was previously reported that the small shelly fossils are dominated by hyolithids, olivooids, zhijinitids, conodontomorphs, yubelichitids, camenitids and algae, with minor amounts of sponge fossils. Large amounts of sponge spicules, diverse in form, have been found for the first time in the Gezhongwu Formation phosphorites at Shixing, Zhijin County, Guizhou Province, of which such spicules as diaxon-triactins, diaxon-tetractins, pentaxon-pentactins and hexon-hexactins account for 30%. These spicules constitute the sponge clastic phosphorites made up of sponge clastics. Meanwhile, it is also expected that the radiation and diversity of sponge animals started as early as in the earliest Early Cambrian. Habit and burying environment of sponge animal are discussed in the paper.     

Eocrinoids from the Cambrian Mantou Formation of Dalian, Liaoning

Cambrian echinoderms,especially eocrinoids,have been reported recently from Guizhou and Yunnan provinces of China,such as the Kaili,Balang,and Guanshan faunas.The present paper reports abundant well-preserved eocrinoids from the Cambrian Mantou Formation of Dalian,Liaoning Province.This new discovery provides additional data on the early evolution of Echinodermata.It also gives us a clue as to where to seek the Cambrian soft-bodied fauna on the margin of the North China Platform.     

Lower Cambrian small shelly faunas from Zhejiang (China)and their biostratigraphical implications

Despite a long history of research on the Early Cambrian in China most available data on small skeletal fossils concern fossil associations of the shallow carbonate platform. Information on skeletal fossils from marginal shelf environments of the Yangtze Platform is scanty, which may reflect the rarity of fossils in deeper sedimentary environments but is also due to limitation of carbonate distribution and outcrops, difficulties in fossil extraction, and a general research focus on the Precambrian-Cambrian boundary beds on the carbonate platform. Here we present a documentation of Meishucunian to Qiongzhusian small skeletal fossils from the lower Hetang Formation and the chert unit at its base from the Jiangshan region, Zhejiang Province, representing a relatively deep shelf environment compared to the inner shelf region. The earliest association (Meishucunian) from the chert unit underlying the Hetang Formation is mainly characterized by the occurrence of Protohertzina anabarica, P. unguliformis, Fengzuella zhejiangensis, and Kaiyangites novilis, which differs somewhat in composition from SSF-associations of typical inner shelf deposits. The enigmatic skeletal fossil Fengzuella zhejiangensis, which exhibits an unusual secretional growth mode previously unrecognized from the Early Cambrian, is described in detail. A younger (Qiongzhusian) fossil association contains numerous arthropod remains, such as disarticulated spines of arthropods (Jiangshanodus- and Kijacus-type), which have previously been considered as conodont-like fossils, and bradoriid valves.     

Paleoceangraphic significance of redox-sensitive metals of black shales in the basal Lower Cambrian Niutitang Formation in Guizhou Province, South China

TheLowerCambrianblackshalesequenceoccursinSouthChinaalonganarc parallellinearbeltex tendingmorethan 16 0 0km .Theseorganic richblackshalesformedinvariousmarineenvironmentsandtypicallycontainhigheramountsofmolybdenum ,nickel,vanadium ,andanumberofothereconomical lyimportantmetalsthandoanyothersedimentaryrocks[1,2 ] .Therefore ,thestudyoftheseblackshaleshasnotonlypaleoceangraphicimplicationbutalsoe conomicsignificance .Marinesedimentssuchasblackshalearecom plexmixturesofdetritalphasesandseawat…     

长江口拦门沙全新世微体化石群特征及其意义

本文通过对长江口拦门沙地区崇明岛、横沙岛三个钻孔的微体古生物综合分析,发现全新世地层中有四个微体化石层,它们分别指示了该地层经历了(由下往上)由滨海-河流相→滨海-河口相→浅海相→河口相的环境演变过程。并结合孢粉和 C~(14)测年资料认为该区全新世地层可以四分,即古全新世、早全新世、中全新世、晚全新世。     

Sponge fossil assemblage from the Early Cambrian Hetang Formation in southern Anhui

Abundant well-preserved large articulated sponge fossils and isolated spicules have been reported from the Early Cambrian Hetang Formation, southern Anhui Province. This unique epifaunal fossil assemblage dominated by articulated sponge fossils is called the Xidi Sponge Fauna. The sponge fauna lived in a quiet oxygenic environment below the storm wave base. Bloom of phytoplankton and rapid sedimentation rate resulted in the deposition of the black shales. Sufficient food supply, lack of other competitors, abundant ecological niches, and demand for oxygen during early Cambrian were in favor of the diversification and evolution of large sponges in the Early Cambrian.     

Phosphatized embryo fossils from the Cambrian explosion

The earliest Cambrian (Meishucunian) phosphatized metazoanOlivooides from the Yangtze platform is represented by dierent developmental stages: from blastula through possible gastrula to tissue differentiation and finally to the hatched animals. The fossilization of embryos opens a new field in palaeontologypalaeoembryology. Embryological studies will be of importance for the understanding of ontogeny and phylogeny of metazoans from the Cambrian explosion.