Lithornithid birds (Aves,Palaeognathae) from the Lower Palaeogene of Denmark

An incomplete sternum and imprints of a right part pelvis and an associated left femur from the uppermost Palaeocene/lowermost Eocene (Fur Formation) of Denmark are assigned to the extinct palaeognath bird order Lithornithiformes Houde 1988, and to the single described family thereof, the Lithornithidae. Morphological features indicate that both individuals were adult birds, smaller than Lithornis cf. nasi, which is represented by an incomplete humerus from the largely contemporaneous, marine Olst Formation in Denmark, and corresponding in size to the smallest known lithornithid, Lithornis hookeri. Lithornithiformes, common in the Palaeocene and Eocene of North America and Europe, were terrestrial birds capable of flight whose remains are often found in aquatic sediments. Both the depositional environment in which the Danish lithornithids were found, and the associated faunal components suggest that the birds were not transported by rivers. Some of the lithornithid species inhabiting NW Europe may have lived and foraged along the shores of the North Sea Basin.     

A review of Late Cretaceous fossil birds from Hungary

We review the previously described Late Cretaceous (Santonian) bird remains from the Csehbánya Formation in the Bakony Mountains of Hungary, augmenting initial work by Ősi ( 2008 ), and add a number of newly collected fossils. All together, the eight fossil specimens so far collected from this site are important to our understanding of avian evolution because they document a large range of taxon body sizes from at least one major lineage (Enantiornithes) and come from a critically undersampled time period in the Cretaceous. Globally, very little fossil bird material has been collected from the middle stages of the Late Cretaceous, the Coniacian and Santonian; most known taxa are either Early Cretaceous (ca. 120 Ma) in age or are from the terminal Campanian and Maastrichtian (ca. 70–65 Ma). Indeed, one of the Csehbánya Formation fossil birds is recognized as a new taxon of large enantiornithine, an avisaurid apparently similar in its largely unfused foot morphology to the Argentine Soroavisaurus and to the North American Avisaurus. The Central European records reviewed in this paper highlight the wide distribution of some Late Cretaceous fossil birds, particularly avisaurid enantiornithines, and lead us to a brief discussion of avian biogeography at the end of the Mesozoic. Copyright © 2010 John Wiley & Sons, Ltd.     

Sedimentation and diagenesis of Lower Eocene sediments at Ölst,Denmark

The Lower Eocene sedimentary environment has been subjected to investigations which seem to support the theories that transgressive conditions prevailed during the Paleogene in Denmark. This is obvious from analyses of grain-size distribution, clay mineral content and the organic matter. The undisturbed sedimentary structures, the absence of burrows and the pyrite content seem to indicate an anaerobic environment during deposition.Analyses of the distribution of Fe, Mg, Ca and Mn indicate close relationship between diagenesis and lithology both in the nature of the diagenetic processes and in the shape of the concretionary bodies.     

衡阳盆地始新世含鱼地层的成因分析

衡阳市郊五马归槽始新世鱼化石保存在黑色湖相纹层中。根据纹层序列的对比,发现该地的鱼化石均为同一层位;根据鱼化石在纹层序列中的具体位置及鱼化石的保存状况,笔者推测鱼群的死亡并非由于季节更替,而是由气候干旱引起的湖水盐度升高所控制;黑白纹层的变化是由大气降雨所致。     

云南元谋古猿动物群化石埋藏学

云南元谋小河-雷老一带含古猿新近系（上第三系）是一套紫红色含砾细砂-粉砂岩，夹有多层黄色砂砾石层。化石埋藏学研究及含化石层岩性特征、组合及沉积构造表明，该层以山前洪积堆积为主，并有发育的扇上河道沉积。通过30余个发掘地点化石野外埋藏资料及数千件化石标本的分析鉴定，化石埋藏类型有两种，埋藏Ⅰ型的化石数量稀少、保存完整，赋存在扇体细粒沉积物中；理藏Ⅱ型化石保存丰富但相当残破，赋存在粗粒沉积的扇上河道各个部位。化石埋藏类型与古气候、古生态有着密切的关系，化石埋藏特征表明该区自然环境分带已形成。元谋古猿动物群的生存时代是一个从森林向草原-灌丛环境过渡的动荡时期。     

Composition and Formation Conditions of Lower Eocene Shallow-Marine Carbonates in Southern Armenia

Lithology and Mineral Resources - Nummulite facies are known to be a good indicator of Eocene shallow-water paleoenvironments. Nummulitic limestones are widespread in the Lower Eocene of...     

三水盆地古近系(土布)心组黑色页岩中黄铁矿的形成及其控制因素

黄铁矿是富有机质沉积的特征矿物。根据TOC/S、TOC/DOP、S/Fe关系以及S TOC Fe多重线性回归分析结果对三水盆地古近系〖HT5”,6”〗土〖KG-*3〗布〖HT5”SS〗心组红岗段黑色页岩中沉积黄铁矿的形成及其控制因素进行了分析。土布心组红岗段黑色页岩的黄铁矿有成岩黄铁矿和同生黄铁矿两种成因组分。红岗段下部（亚段A）有机碳含量普遍较低,底部水体以弱氧化条件为主,硫酸盐还原作用发生于沉积物/水界面以下,黄铁矿为成岩成因,其形成主要受有机质的限制。红岗段中上部（亚段B和C）的沉积条件变化频繁,其有机碳含量变化幅度大。富有机质（TOC>4%）岩层形成于缺氧的底部水体条件下。水体中可含H2S,碎屑铁矿物在埋藏之前即与之在水体中反应形成同生黄铁矿。这一过程不受有机质的限制,而是受活性铁与H2S接触时间的限制。同时,由于大量淡水输入导致硫酸盐浓度的降低,从而对硫化物形成有一定的限制作用。对于低有机质（TOC<4%）样品,黄铁矿由同生和成岩组分组成。其中以成岩黄铁矿为主,其形成过程主要受有机质限制,而同生黄铁矿受铁矿物与H2S接触时间的限制。     

鲁东诸城地区晚白垩世恐龙集群埋藏地沉积相与埋藏学初步研究

鲁东诸城盆地白垩系由下向上包括林家庄组、辛格庄组和红土崖组。下白垩统林家庄组为杂色粗碎屑岩系;上白垩统辛格庄组为杂色细碎屑岩系,红土崖组为砖红色砂岩、砾岩互层沉积夹玄武岩(73.5Ma),为恐龙化石埋藏层位,并与区域上莱阳青岛龙及恐龙蛋化石等产出层位可以对比。诸城地区晚白垩世时期主要为冲洪积沉积环境,辛格庄组上部为洪泛平原粉砂岩—细砂岩—灰质土加积序列,局部夹扇中辫状河砾岩、粗砂岩,红土崖组下部与下伏辛格庄组顶部过渡部位是冲积扇泥石流、辫状河和洪泛平原粉砂泥质砾岩、砂岩加积沉积序列。识别出与冲积扇沉积体系相关的3种埋藏相类型:冲积扇泥石流、洪泛平原和辫状河河道(砂砾岩),前二者是研究区主要的埋藏相类型。所含化石主要为鸭嘴龙的残体骨骼,个体大小参差不等,互相间可叠盖一起,同时也有孤立发育的骨骼化石。高密度、单一种类恐龙残体骨骼化石的沉积、埋藏特征代表了恐龙集群埋藏—沉积事件。     

凯里生物群中始海百合类形态功能、生态及埋藏特征初探

贵州剑河八郎中寒武世凯里生物群中始海百合十分丰富,化石标本多达1万多件,分属长茎型的卢氏中国始海百合（Sinoeocrinus Zhao, Huang et Gong,1994）及短茎型的球形中国始海百合（Sinoeocrinus globus Zhao et al, 1999）。它们均具有腕枝、萼、茎及吸盘,少数标本见有肛锥。幼年体缝孔不发育,成年体具有较发育的缝孔。大部分个体为单体生活。短茎型的萼呈球形,茎短,吸盘大,常固着在腕足动物外壳及三叶虫背壳碎片上。长茎的萼呈长椭圆球形茎长,吸盘小,常固着在砂泥质海底。两个种的腕肢也有差别,长茎的直长,短茎的旋转生长,显示两个种的形态差别及多样性。由于始海百合死亡后迅速被掩埋,80%以上的个体保存完整。化石大部分保存无定向性,显示静水环境,海底紊流很少,不仅显示原地埋藏特征,也为凯里生物群是原地埋藏提供了重要证据。     

Origin of spheroidal chert nodules, Drunka Formation (Lower Eocene), Egypt

Chert nodules of the Drunka Formation (Lower Eocene) are mostly spherical, have diameters from 40 to 120 cm, are quasi-uniformly spaced 2–3 m apart in the plane of bedding, have concentric internal structure and, except for rare small (<6 cm) solid chert nodules, are less than 85% chertified. Nodules formed after moderate alteration of limestone by meteoric water (δ¹⁸O_calcite = –4 to –8‰) at shallow (<100 m) burial depths; more extensive alteration of limestone (δ¹⁸O = –10 to –16‰) by meteoric water followed nodule growth. Chertification was by low-temperature meteoric water (δ¹⁸O_quartz = +18‰ in margins to +22‰ in nuclei) at shallow burial depths. Meteoric water may have invaded the Drunka Formation in association with shelf progradation during the Early Eocene, or during the development of a Middle Eocene unconformity. Replacement of carbonate mud by microcrystalline quartz was the dominant chertification process, but fossils were replaced in part by fine-grained equant megaquartz, quartzine and chalcedony; the last of these occurs in places as beekite. Opal A-secreting marine organisms are the inferred source of silica, but none are preserved. There is no compelling evidence of an opal-CT precursor, so quartz may have formed by direct precipitation. Self-organization processes of enigmatic character established the spacing pattern of the nodules and also the Liesegang-banded internal structure of the chert nodules. Nodules grew chiefly by diffusive supply of silica, although one locality has elongate nodules that grew when there was some porewater advection. Chertification patterns and δ¹⁸O values of both calcite and quartz indicate that nodule growth was complex and variable. Some nodules probably grew from the centre outwards. Many nodules, however, initially grew simultaneously across the entire nodule, but late-stage growth was predominantly at the outer margins or at selective internal sites.     

Taxonomy, facies relationships and palaeobiology of bakevelliid bivalves from the Lower Cretaceous of west-central Argentina

Cretaceous bakevelliids in Argentina are restricted to the Lower Cretaceous. They are recorded in shallow marine deposits in two Mesozoic basins located in the Andes foothills in Patagonia. In the Austral Basin (44°–55°S) there is only one genus, Gervillella, represented by a single specimen from the Barremian. In the Neuquén Basin (30°–40°S) two genera, Gervillaria and Gervillella, occur, ranging from the Berriasian to the Lower Barremian. In the Pilmatué Member of the Agrio Formation two species are identified: Gervillaria alatior (Imlay) and Gervillella aviculoides (J. Sowerby). The former is also recorded in Mexico while the latter is more widespread, occurring in Europe, Asia, and Africa. In the Bajada del Agrio section they come from eight tabular shell beds located near and on top of shallowing-upwards cycles. They were abundant only in four of these levels. These shell beds are interpreted as having been deposited in the mid-ramp (middle of cycles), and upper mid-ramp (top of cycles). A functional analysis of shells revealed two life habits: epibyssate and endobyssate.     

Facies analysis and high-resolution sequence stratigraphy of the Lower Eocene shallow marine Ametlla Formation, Spanish Pyrenees

The Lower Eocene Ametlla Formation of the Ager Basin, Spanish Pyrenees, is a rapidly deposited shallow marine unit formed in a setting characterized by syn-sedimentary tectonic activity. Mapping of the formation over a distance of 25 km was conducted according to sequence stratigraphical principles with emphasis on facies analysis. Twelve facies, grouped in five facies associations, have been recognized in the Ametlla Formation. The studied succession records a vertical transition from deltaic systems prograding onto a sediment-starved shelf, via estuarine deposits associated with incised valleys, to sandbar complexes in a tidal seaway. In terms of sequence stratigraphy, three scales of genetic sedimentary units were recognized. (1) At the regional scale, elements of two 3rd-order composite sequences (sensu Exxon) have been recognized. These include a 3rd-order highstand sequence set encompassing the lowermost part of the Ametlla Formation and the underlying Passarella Formation, and a 3rd-order transgressive sequence set that constitutes the middle parts of the Ametlla Formation. The sequence sets are separated by an unconformity with up to 35 m of incision that is interpreted as a major sequence boundary. It is argued that the incised valleys associated with this unconformity were infilled during landward-stepping of the shelfal depositional system. Basinwards, the unconformable surface becomes subhorizontal and is overlain by a 2 m thick oyster bed formed in a sediment-starved setting subsequent to flooding of the incised valleys (which still acted as sediment conduits). Sandstones dominate the transgressive sequence set, whereas the highstand sequence set is dominated by siltstones, particularly in the lower part. In the transgressive sequence set, an upward increase in sand content and calibre is observed, relatable to punctuations of the transgressive trend by high-frequency sea-level fluctuations, and to downslope redistribution of sand. (2) At the subregional scale, detailed mapping indicates the presence of five 4th-order sequences. The 4th-order sequence boundaries are associated with sediment bypassing and minimal erosional relief, and were created by forced regressions during periods of relative sea-level fall. Sharp-based sandstones overlying these unconformities are believed to have accumulated during subsequent rise of relative sea-level. Where 4th-order maximum flooding surfaces can be recognized, the sequences may be subdivided into a sandstone-dominated transgressive systems tract and a siltstone-dominated highstand systems tract. (3) At the local scale, 2–9 5th-order parasequences are present within the 4th-order sequences. Superimposed parasequences are separated by flooding surfaces characterized by bioclastic accumulations, pervasive burrowing and extensive calcite cementation. The parasequences are commonly stacked in a landward-stepping manner.     

伊通盆地鹿乡断陷始新统双阳组沉积相与沉积演化

经岩芯观察,录井、测井资料分析,结合地震反演及粒度分析等方法,编制出伊通地堑鹿乡断陷星27井区始新统双阳组各段的砂岩等厚和地层厚度等单因素图件。采用单因素分析、多因素综合作图法,系统研究了双阳组的沉积特征及沉积演化规律。研究区双阳组主要发育扇三角洲、水下扇和湖泊沉积体系,并可进一步识别出9种亚相、13种微相。其中,双一段以湖泊沉积体系为主;双二段以扇三角洲沉积体系和水下扇沉积体系为主;双三段以湖泊沉积体系为主,水下扇不发育。双阳组沉积时期,构成了一套完整旋回,双一段和双二段下部为进积过程,双二段上部和双三段为退积过程。     

Molecular composition and chemotaxonomic aspects of Eocene amber from the Ameki Formation,Nigeria

The molecular composition of fossil resin from the Eocene Ameki Formation, southern Nigeria has been analyzed by infrared spectroscopy, pyrolysis–gas chromatography–mass spectrometry and thermochemolysis gas chromatography–mass spectrometry to determine the structural class and botanical source of the resin. The pyrolysis products were dominated by bicyclic products derived from regular labdatriene structure and lacked succinic acid indicating Class Ib type amber. The biomarker compositions in the pyrolysates are dominated by sesquiterpenoids of the cadinane and bisabolane classes that are common constituents of higher plants and labdane type diterpenoids. The exclusive presence of labdane type diterpenoids and the absence of higher plant triterpenoids strongly suggest that the amber was derived from a gymnosperm (conifer) botanical source. This observation contrasts with the angiosperm source previously suggested for the resin based on the palaeobotanical studies of the host sediments. The specific family source within the conifers could not be ascertained based on the molecular composition of the resin. However, the presence of methyl-16,17-dinor-callitrisate pointed to the Cupressaceae family although other Cupressaceae biomarker indicators were not detected in the resin.     

下刚果盆地白垩系盐构造的形成演化

下刚果盆地具有巨大的油气资源和潜力,盐构造控制着油气成藏和分布。其盐岩流动的不规律性,增加了盐构造的形成演化和演化期次分析的难度,前人主要通过平衡剖面恢复的方法对断裂等构造形态进行定量恢复,但对盐构造形成演化过程的认识及变形期次刻画的准确性明显不足。本文基于数值模拟手段,通过沉积地层的分时期加载方法,正演了下刚果盆地的构造演化过程,探讨并明确了盐构造的演化阶段。数值模拟结果表明,下刚果盆地盐构造的形成主要分为3个阶段：盐岩初始流动阶段、盐构造形成阶段和构造稳定阶段。形成底辟构造的主要时期是古新世-中新世。其中,古新世-渐新世开始形成底辟构造,中新世多个大规模底辟构造形成,且该时期是盐构造活动最强烈时期。在此基础上进一步完成了下刚果盆地盐构造活动变形与重力作用流动、上覆沉积地层厚度不均一以及沉积扇体的进积作用关系分析。     

New Species of Enantiornithes (Aves: Ornithothoraces) from the Qiaotou Formation in Northern Hebei,China

<正>We report on a new species of enantiornithine bird from the Lower Cretaceous Qiaotou Formation of northern Hebei,China.The new taxon,Shenqiornis mengi gen.et sp.nov.,possesses several enantiornithine synapomorphies but is unique from other known species.The specimen has a well-preserved skull that reveals new information about enantiornithine cranial morphology.The new taxon possesses a large postorbital with a long tapering jugal process indicating that some enantiornithines may have had a fully diapsid skull,as in Confuciusornis.The tooth morphology of the specimen is unique and likely represents a previously unknown trophic specialization within Enantiornithes.     

川西北下二叠统栖霞组有利成岩作用与孔隙演化

据宏观、微观及地球化学特征等综合分析,川西北下二叠统栖霞组储层段主要的建设性成岩作用有同生一准同生期溶解、埋藏期溶解、构造抬升期溶解、混合水白云石化、埋藏白云石化及重结晶作用.其中埋藏期溶蚀和埋藏白云石化作用对储集层的储集空间贡献最大,其产生的晶间孔、晶间溶孔、洞、缝是现今该层段主要的储集空间;其次是重结晶作用.重结晶作用对储集空间的直接贡献不大,但重结晶作用提高了岩石的有效孔隙度和渗透率从而为后期的溶蚀作用提供了条件:而同生期的溶解作用形成的孔隙由于后期的压实、胶结等作用破坏而几乎消失殆尽.     

鄂西地区早奥陶世分乡期生物群落演化与沉积环境变迁

鄂西地区下奥陶统分乡组生物群按其生态特征划分为3个生态组合,10个化石群落或埋藏群:(1)壳相组合:Tritoechia-Pelmatozan群落?Tritoechia-Pomatotrema群落;(2)礁相组合:Archaeoscyahia群落?Ar-chaeoscyphia-Calathium群落?Batostoma-pelmatoxoan群落?Batostoma群落?Calathium-蓝绿藻群落;(3)静水相组合:Acanthograptus-Dendrograptus群落?Nanorthis-Psilocephalina埋藏群?Yichangopora?群落?它们之间随环境变化显示出由壳相组合→礁相组合→静水相组合→壳相?礁相组合的演化序列,造礁生物之间也存在着一定的演替和取代?群落演化特征反映了研究区分乡期至红花园期沉积环境演变过程是一个海水不断加深复又变浅的海侵-海退旋回,这与早奥陶世特马豆克晚期至阿伦尼格早期世界性海平面升降过程是完全一致的     

塔里木盆地塔河地区下石炭统巴楚组沉积演化

以塔里木盆地加里东期和海西两期构造运动为背景,结合现有的岩心、露头、测井、录井和地震资料,对巴楚组可识别出早期的辫状河三角洲沉积,中期的潟湖沉积和盐湖沉积,以及晚期的咸化潟湖沉积。本文分别从横向上和纵向上对塔河地区巴楚组沉积演化进行深入分析;总结了巴楚组构造运动与沉积响应之间的关系,以期为该地区的下石炭统巴楚组的进一步勘探提供科学依据。