High-energy sedimentary events in lagoonal successions of the Upper Silurian of Podolia, Ukraine

Three Late Silurian carbonate profiles of the Malynivtsy and Skala Formations from Podolia (western Ukraine) are discussed in terms of sedimentation dynamics. Their common feature is the appearance of thick, stromatoporoid-rich beds within fine-grained peritidal deposits. These intercalations are composed of fossils typical of offshore sedimentary environments. In the most spectacular case, a channel, several tens of metres wide and infilled with stromatoporoids, is incised in a peritidal cyclic complex. The successions investigated exhibit sedimentary features that are diagnostic of onshore redeposition. Independently of the scale of the recorded sedimentary events, the onshore redeposition was caused by factors with energy levels exceeding those of average storms, probably by hurricanes or even tsunami waves. The dynamic nature of some of the stromatoporoid beds has to be taken into account when constructing the curves illustrating bathymetrical and facies development of the Silurian succession of Podolia. The genesis of lens-shaped stromatoporoid beds, elongated depending on their origin, either parallel or perpendicular to the facies belts, should be considered an important factor in reconstructions of the depositional architecture of sedimentary hydrocarbon collectors.     

内蒙古古生代巴特敖包剖面的再研究

巴特敖包剖面(即巴特敖包—仲阿木乌苏剖面)是内蒙古巴特敖包地区最有代表性的剖面,也是巴特敖包群的典型剖面。以往依据底栖大化石的研究,将其全部归入“上志留统”。依据牙形刺的研究,可以证实,巴特敖包剖面内部有不少断层,巴特敖包剖面的地层是由志留系—泥盆系—志留系—泥盆系地层交错而成,并非是一个连续的剖面,也不能全部归入“上志留统”。巴特敖包群应当解体,不再使用。巴特敖包剖面仍需详细研究,有可能发现志留系—泥盆系连续的界线层剖面。     

Retiolitid graptolites from the collection of HermannJaeger in the Museum für Naturkunde, Berlin (Germany). I.Neogothograptus andHoloretiolites

Isolated material of Ludlow (Upper Silurian) retiolitid graptolites are described from isolated material in theJaeger collection of the Museum für Naturkunde (Humboldt Universität Berlin, Germany). This material from glacial erratic boulders of northern Germany has never been published, even though it yields important structural information for retiolitid taxonomy. The astogeny and formation of the clathrial and reticular lists ofNeogothograptus andHoloretiolites rhabdosomes is discussed in some detail. New species includeNeogothograptus ornatus n. sp. andNeogothograptus eximinassa n. sp. Hermann Jaeger recognized both species as new and named them in his collection, but not publish the material.Neogothograptus thorsteinssoni Lenz &;Kozlowska-Dawidziuk andNeogothograptus romani Koz?owska-Dawidziuk have been recognized for the first time in north German glacial erratic boulders.     

Early symbiotic rugosan endobionts in stromatoporoids from the Rhuddanian of Estonia (Baltica)

The earliest known symbiotic rugosan endobionts occur in stromatoporoids from the early Rhuddanian of Estonia. The stromatoporoid Ecclimadictyon nikitini from the Tamsalu Formation contains the rugosan Donacophyllum middendorffii endobiont. A stromatoporoid Clathrodictyon boreale from the Varbola Formation contains Streptelasma estonica and Bodophyllum sp. endobionts. There are up to three endobiotic rugosans per stromatoporoid host. Stromatoporoid hosts were beneficial for symbiotic rugosans as elevated substrates on a seafloor that offered a higher tier for feeding; they also offered enhanced substrate stability. Stromatoporoids of the end‐Ordovician mass‐extinction recovery fauna hosted a diverse fauna of symbiotic endobionts. There were few if any negative effects of this mass extinction on the symbiotic endobionts.     

Acritarch distribution along an inshore–offshore transect in the Gorstian (lower Ludlow) of Gotland, Sweden

To better understand palaeoecological signatures in Palaeozoic acritarch assemblages, the distribution of palynomorphs has been quantitatively studied in eight localities from the Gorstian, lower Ludlow (Late Silurian) of Gotland, Sweden. The localities are situated along an inshore–offshore transect comprising shallow marine lagoonal environments to distal shelf facies. Process-bearing acritarchs and sphaeromorphs constitute the main components within the palynomorph assemblages. The lateral distribution of palynomorphs exhibits characteristic features at three different levels as follows. (1) With regard to the overall composition of the palynomorph assemblages, the abundance of process-bearing acritarchs increases towards the distal shelf, while the abundance of sphaeromorphs decreases. (2) At the generic level, the acritarchs Micrhystridium and Dilatisphaera are more abundant in the proximal facies, while Evittia, Percultisphaera and Oppilatala are more common in distal environments. (3) At an infrageneric level, Micrhystridium morphotypes with shorter processes are mainly present in proximal environments, while those with longer and ramified processes occur in more distal shelf environments. The palynomorph distribution along the inshore–offshore transect highlights the potential of acritarchs and prasinophytes as palaeoenvironmental indicators.     

塔里木盆地下志留统遗迹组构及其环境解释

遗迹组构是由生物成因改造的沉积岩组构,是物理过程和生物过程相互作用的产物,文中运用生物扰动指数和遗迹组构组分图解综合分析方法在塔里木盆地下志留统塔塔埃尔塔格组中建立４个遗迹组构,即反映下临滨和滨外环境的Ｈelminthopsis-Diplocraterion复合遗迹组构,反映了下临滨环境的Ｐalaeophycus遗迹组构和Ｓkolihos遗迹组构,反映中上临滨环境的Ｓkolithos-Arenicolites遗迹组构,对遗迹化石和生物扰动构造进行阶层分析,从中识别出受固底质控制的遗迹化石Ｄiplocraterion,常代表层序地层学中的重要界面。     

西秦岭迭部地区早志留世四射珊瑚动物群

西秦岭迭部地区下志留统拉垅组四射珊瑚已报道８属１０种,作者近年对该珊瑚动物群详加研究,经鉴定计有９种,１３属。１８种,描述其中１１属１２种（包括５新种）,即Ｂｒａｃｈｙｅｌａｓｍａ ｓｐ．,Ｐａｒａｍｐｌｅｘｏｉｄｅｓ ｓｐ．, Ｋｏｄｏｎｏｐｈｙｌｌｕｍ ｃｆ．ｌｅｉｊｉａｔｕｎｅｎｓｉｓ Ｇｅ ｅｔ Ｙｕ,Ｅｏｓｔａｕｒｉａ ｍｉｎｏｒ（Ｃｈｅｎ）,Ａｍｐｌｅｘｏｉｄｅｓ ｃｈａｏｉ（Ｇｒａｂ     

浙江长兴志留纪真盔甲鱼类新材料及真盔甲鱼目系统发育关系的讨论

对浙江长兴地区志留纪真盔甲鱼类的新材料进行了研究。形态学研究结果表明 ,雷曼煤山鱼 (Meishanaspislehmani)一属种成立 ,并非浙江中华盔甲鱼 (Sinogaleaspiszhejiangensis)的同物异名。在此基础上 ,运用分支系统学的原理 ,对真盔甲鱼目的系统发育关系进行了探讨 ,分析结果表明 ,中华盔甲鱼属现有的 3个种并未组成一个单系类群 ,而是一个并系类群。浙江中华盔甲鱼不能归到中华盔甲鱼属 ,建议另立一新属。     

东秦岭下志留统的笔石

笔石采自河南淅川下志留统张湾组,其时代与华中区龙马溪组相当。包含Ｄ．ｔｒｉａｎｇｕｌａｔｕｓ,Ｏ．ｃｏｍｍｕｎｉｓ和Ｍ．ｓｅｄｇｗｉｃｋｉｉ３个笔石带,可以与国内外同时代笔石带相对比。共记述正笔石目２科９属１５种,其中含２新种和１新亚种。     

Gonad pouches in a new clam-like monoplacophoran from the Silurian of Sweden

Beyrichidiscus fecundatus n. gen. n. sp. is described from the Upper Silurian of Gotland, Sweden. The minute, isostrophically coiled mollusc exhibits profound allometry and is considered to have been a monoplacophoran on the basis of functional interpretation of apertural structures. A clam-like, semi-infaunal mode of life is suggested. A pair of prominent lateral swellings in the adult shell are interpreted as reflecting the location of the gonads.