新疆早寒武世玉尔吐斯小壳动物群再研究

新疆乌什—阿克苏地区下寒武统玉尔吐斯组的小壳化石丰富,已描述了近50属90种,包括1个新属,15个新种。计有软舌螺类、似软舌螺类、单板类、腹足类、骨针类及分类位置未定的化石,还有节肢动物门的高肌虫类。按小壳化石在地层纵向出现的次序及其代表性,可将玉尔吐斯组小壳动物群的比石划分为3个带,即1.Anabarites trisulcatus带;2.Cambroclavus-Aurisella带;3.Adyshevitheca-Xinjiangella带。其中1带可与梅树村阶I.Anabarites-Protohertzina带对比;2—3带大致可与梅树村阶Ⅱ.Paragloborilus-Siphogonuchites带—Ⅲ.Sinosachites-Lapworthella带对比。因Aanbarites trisulcatus的发现,证实玉尔吐斯组的下界可与梅树阶的底界对比;玉尔吐斯组顶部发现的高肌虫有别于筇竹寺阶的高肌虫。前者与大量梅树村期小壳动物共生,可以认为梅树村期已经出现高肌虫的先遣分子。     

鄂东北早元古代沉积变质锰矿元素矿物组合特征

鄂东北早元古代沉积变质锰矿是我国时代最古老的锰矿之一,是由早元古代锰质碳酸盐岩经区域变质作用而成,后又经风化富集形成工业矿床。由于特殊的地质构造背景和成矿作用的多阶段性,元素和矿物组合复杂,具有独特性。本文研究了各种组分的演变关系和元素集散因素,为锰质碳酸盐岩在高压绿片岩相区域动力变质及其后表生作用中的演变提供了一个实例。     

Fossil caddisflies (Insecta: Trichoptera) from the Early Cretaceous of southern England

The first fossil caddis cases from the Early Cretaceous (Wealden) of SE England are described and named Conchindusia rasnitsyni ichnosp. nov., Piscindusia sukachevae ichnogen. et isp. nov., ?Ostracindusia vyalovi ichnosp. nov. and Pelindusia percealleni ichnosp. nov. In addition, the necrotauliid caddisfly Paratrichopteridium purbeckianum (Handlirsch) comb. nov. from the earliest Cretaceous (Purbeck Group) of Dorset is redescribed.     

Evidence of glaucophane-schist facies metamorphism in the East Karkonosze complex,West Sudetes,Poland

In the East Karkonosze complex (Karkonosze = Riesengebirge), which occurs at the northern margin of the Bohemian massif, rocks of the glaucophane-schist facies and transitions between the glaucophane-schist facies, greenschist facies and epidote-amphibolite facies are present. They belong to the Leszczyniec Volcanic Formation (LVF) of Cambrian/Ordovician age and to the mainly metasedimentary Czarnów Schist Formation (CSF) of Ordovician/Silurian age. Similar high-pressure, low-temperature rocks occur in the southern Karkonosze and in the Kaczawa Mountains within metavolcanic formations of approximately the same age. Petrographic and electron probe studies show complex relationships between minerals including chemical zoning. In the East Karkonosze three stages of metamorphism pre-dating contact metamorphism by late Variscan (lowermost Upper Carboniferous) granite intrusion were distinguished [stage 1: ocean floor, amphibolite facies (observed only in part of the LVF); stage 2: high-pressure, low-temperature, variably glaucophane-schist facies, high-pressure greenschist facies and epidote-amphibolite facies; stage 3: medium-pressure greenschist facies accompanied by strong deformations]. Glaucophane-schist facies rocks formed in stage 2 survived the later stages of metamorphism only in the southern part of East Karkonosze, i. e. in Lasocki Range and Rýchory. Using the Maruyama et al. (1986) geobarometer the glaucophane-bearing rocks formed at 6.5–7 Kb, those with crossite at 5–6 Kb and rocks with magnesioriebeckite/riebeckite at 4–5 Kb. Other estimates for glaucophane-bearing rocks give somewhat higher values of pressure, i. e. 7–12 Kb at temperatures between 300 and 530°C. The highest temperatures are recorded in the glaucophane- and garnet-bearing rocks. Stilpnomelane may occur in all of these rocks. The subduction/obduction episode responsible for this high-pressure, low-temperature metamorphism is considered to have taken place in the early Variscan, although no geochronology is yet available to confirm this.     

华北地台早古生代沉积建造及台地演化

本文根据大量的野外实际资料和实验室的研究工作,运用沉积建造学的基本理论和方法,对华北早古生代的沉积建造类型和沉积特征进行了阐述。根据岩石的共生组合关系划分出八种沉积建造类型,二大类沉积建造系列;在台地的内部和边缘可以识别出二种不同类型的地层格架和几何形态;华北早古生代的演化历史可划分出4个发展阶段,它不仅概括了研究区的沉积历史和构造历史,而且在理论上指导了有关的研究工作。     

鄂尔多斯早古生代古构造

用野外露头剖面、钻井剖面和地震剖面相结合的综合研究方法,首先用人工合成记录结合11口井的VSP资料,对鄂尔多斯下古生界进行层位标定。在此基础上,对鄂尔多斯全区下古生界371条共长15 683 km的地震剖面进行了重新处理和地层解释,这大大提高了解释精度。以此为基础,把鄂尔多斯下古生界划分为5个地层单位,即寒武系中下部、寒武系中上部及冶里组和亮甲山组、马家沟群下部、马家沟群上部、平凉组和背锅山组,并作出了它们的等厚图。从这些等厚图可以看出：前4个地质时期的古构造格局为“一隆三凹”,即西缘凹陷、南缘凹陷和东缘凹陷(或东部凹陷)呈“U”形从西南东三面包围着一个中部隆起。最后一个地质时期的古构造格局为“一隆二凹”,即西缘凹陷和南缘凹陷呈“L”形镶嵌在一个巨大的鄂尔多斯隆起的西缘和南缘。到奥陶纪末,鄂尔多斯全区以及整个华北地台均变为隆起区,从而结束了鄂尔多斯隆起和凹陷并存的历史。     

丹东地区中生代地层-古生物

丹东地区小岭组植物化石共9属12种。动物化石腹足类4属6种,叶肢介1属2种。均为首次发现。这些化石的发现为小岭组应属早白垩世而不属侏罗纪,提出了令人信服的证据。同时,阐述了古地理环境和地层特征,并与邻区进行了对比。     

Diversification of skeletal microstructures of organisms through the interval from the latest Precambrian to the Early Cambrian

From the latest Precambrian to the Early Cambrian was the most important phase throughout the evolutionary history of life on the earth. The diversification of latest Precambrian multicellular organisms was obvious and some of them began to form primary s…     

重庆合川自流井组植物化石的发现

描述了发现于合川自流井组东岳庙段的三种似木贼植物化石,即Equisetites flus Harris,E．1ateralis(Phillips)和E．columnaris(Brongn．)Phillips。标本保存良好,依据植物和双壳类化石的分布关系,提出自流井组东岳庙段的时代为早侏罗世晚期至中侏罗世早期。同时,分析了东岳庙段的岩相特征和沉积环境。     

浙江沐尘岩体与西山头组火山岩的岩浆同源性分析

沐尘岩体与旁侧西山头组火山岩、潜火山岩在空间上密切共生,形成时间相近;岩石类型都属中酸性岩类;具有相近的岩石化学成分,均属弱碱质岩系;各种岩石的稀土配分曲线除Eu外具有基本一致的型式,微量元素配分曲线形态也基本一致,说明它们是同源岩浆演化的产物。其岩石类型、岩石化学和稀土元素、微量元素地球化学方面具有相似性和一致性,岩浆演化均有反序现象,说明它们属同熔型火山-侵入岩组合。根据2004年国际地层委员会公布的侏罗系与白垩系的分界年龄(145.5±4.0Ma),并结合沐尘岩体与旁侧西山头组火山岩的成因关系,沐尘岩体的形成时代确定为早白垩世早期似更合理。