Foraminiferan-calcimicrobial benthic communities from Upper Cretaceous shallow-water carbonates of Albania (Kruja Zone)

From the Kruja Zone of Albania, shallow-water carbonates assigned to the lower Campanian are described and grouped into six microfacies types of shallow subtidal to intertidal depositional settings. The limestones display internal layering suggestive of microbial fabrics with abundance of nubeculariid foraminifera, incertae sedis Thaumatoporella Pia, and subordinate calcimicrobes of possible cyanobacterial origin: Gahkumella Zaninetti, Girvanella sp., and Decastronema kotori (Radoičić). The nubeculariid morphotypes with ornamented tests and microbial coatings reveal some kind of mutualistic relationship comparable to Late Palaeozoic–Mesozoic Tubiphytes Maslov and Crescentiella Senowbari-Daryan et al. The present study expands our knowledge on the micropalaeontological characteristics of the Late Cretaceous “Decastronema–Thaumatoporella association” widespread in carbonate platforms of the peri-Mediterranean region. Our findings indicate that nubeculariids may have played an important binding role in Late Cretaceous peritidal laminated limestones.     

Hummocky cross-stratification-like structures in deep-sea turbidites: Upper Cretaceous Basque basins (Western Pyrenees, France)

Hummocky cross-stratification is a sedimentary structure which is widely interpreted as the sedimentary record of an oscillatory current generated by energetic storm waves remobilizing surface sediment on the continental shelf. Sedimentary structures named hummocky cross-stratification-like structures, similar to true hummocky cross-stratification, have been observed in the Turonian–Senonian Basque Flysch Basin (south-west France). The bathymetry (1000 to 1500 m) suggests that the observed sedimentary structures do not result from a hydrodynamic process similar to those acting on a continental shelf. The morphology of these three-dimensional structures shares similarities with the morphology of hummocky cross-stratification despite a smaller size. The lateral extent of these structures ranges from a few decimetres to many decimetres; they consist of convex-up domes (hummock) and concave-up swales with a non-erosive base. Four types of hummocky cross-stratification-like geometries are described; they occur in association with structures such as climbing current ripple lamination and synsedimentary deformations. In the Basque Flysch, hummocky cross-stratification-like structures are only found in the Tc interval of the Bouma sequence. Hummocky cross-stratification-like structures are sporadic in the stratigraphic series and observed only in few turbidite beds or bed packages. This observation suggests that hummocky cross-stratification-like structures are linked genetically to the turbidity current but form under a very restricted range of parameters. These structures sometimes show an up-current (upslope) migration trend (antidunes). In the described examples, they could result from standing waves forming at the upper flow interface because of Kelvin–Helmholtz instability.     

藏南岗巴地区上白垩统海相碳酸盐岩碳稳定同位素研究

本文对藏南岗巴地区上白垩统海相碳酸盐岩的碳稳定同位素组成特征及变化趋势进行了研究,对比分析了藏南其它地区及欧洲同时代地层,认为岗巴地层的碳稳定同位素的记录很好地响应了白垩纪期间全球性的缺氧事件。通过对岗巴地区岩石地层学及区域环境的分析说明,全球性的海平面升降及板块运动造成了大洋溶解氧含量的波动是碳稳定同位素δ¹³C值偏移的根本原因。     

Biofacies of Upper Jurassic and Lower Cretaceous sediments of central West Siberia

Paleontological study of Upper Jurassic and Lower Cretaceous sediments recovered by boreholes in the Agan-Vakh and Nadym-Vengapur interfluves clarified environments of their deposition. As is shown, influx of siliciclastic material to central areas of the West Siberian sea basin varied through time. Taxonomic composition and ecological structure of nektonic and benthic fossil assemblages are analyzed and considered in terms of environmental factors such as hydrodynamics, aeration, temperature, and salinity of seawater.     

羌塘盆地半岛湖地区上侏罗—下白垩统生物礁相碳酸盐岩对海水信息的保存性评估

有关海相碳酸盐成岩蚀变性及其对海水信息保存性的研究是一个未曾被人们重视的领域,从而限制了古海洋学及其相关学科的研究水平。近年来,这一研究领域逐渐得到学者们的重视。本文对羌塘盆地半岛湖地区上侏罗统-下白垩统生物礁相碳酸盐岩样品的微观组构观察、阴极发光分析、化学分析和同位素分析等研究表明,大部分样品都具有较低的Mn含量和较高的Sr含量,所有样品均具有较低的Mn/Sr比值,样品δ¹³C值和δ¹⁸O值分布范围波动较小。不同类型岩性对海水信息的保存性按含生屑泥晶灰岩→泥晶粒屑灰岩→粒屑泥晶灰岩→礁灰岩围岩部分→礁灰岩生物骨架部分的顺序依次变差。     

Lamniform sharks from the Cenomanian (Upper Cretaceous) of Venezuela

Sampling of Cenomanian fossil-rich horizons within the La Luna Formation of two localities in the Zulia and Trujillo states (northern Venezuela) yielded numerous shark teeth belonging to various species within the order Lamniformes (Mackerel sharks). Twelve lamniform species were identified including three new species (Squalicorax lalunaensis sp. nov., Squalicorax moodyi sp. nov., Acutalamna karsteni gen. et sp. nov.) and the genus Microcarcharias gen. nov. is proposed to accommodate with the peculiar morphology of the small-sized odontaspidid M. saskatchewanensis. Other taxa reported here include Cretoxyrhina mantelli, Cretolamna sp., cf. Nanocorax sp. and five Squalicorax species left in open nomenclature. This is the first report of chondrichthyans from the mid-Cretaceous of Venezuela and one of the few records of this group from the Cenomanian of South America. The composition of these assemblages suggests some degree of endemism in the La Luna Sea but also possible connexions with the Western Interior Seaway. One of the most striking features of these assemblages is the high anacoracid diversity (eight species) despite the corresponding outer shelf/upper slope palaeoenvironments of the La Luna Formation. The high diversity of these opportunistic predators is probably related to the high diversity of medium to large marine vertebrates that provided food resources.     

A new species of Platanus from the Cenomanian(Upper Cretaceous) in eastern Heilongjiang,China

The stratigraphic division and sequence of the Upper Cretaceous sediments in eastern Heilongjiang Province,China,have been ambiguous and controversial,mainly due to a lack of biostratigraphically useful fossils and related radiometric dating.A new species of angiospermous fossil plant.Platanus heilongjiangensis sp.nov.,from Qitaihe in eastern Heilongjiang has been found in sediments conformably above which zircons from a rhyolitic tuff has been dated by U-Pb radiometric methods as 96.2± 1.7 Ma.indicating that the Upper Houshigou Formation is of Cenomanian age.This discovery not only provides new data to improve our stratigraphic understanding of the Houshigou Formation,but also shows that Platanus flourished in the early Late Cretaceous floras of the region.This new study also indicates active volcanism taking place in the eastern Heilongjiang region during the Cenomanian of the Late Cretaceous.     

An interesting new species of Sisyridae (Neuroptera) from the Upper Cretaceous Taimyr amber

Prosisyrina sphinga sp. nov. (Neuroptera: Sisyridae) is described from Upper Cretaceous (Santonian) Taimyr amber of northern Siberia (Yantardakh locality). The new species is preliminary assigned to this Cretaceous genus, mainly based on character states of the maxillary palpus and the hind wing vein M and crossvein 1r-m, and the presumable absence of tibial false spurs. However, the structure of the costal space and the RP branching in the hind wing indicate that it may belong to a new, closely related genus. The discovery of this second species from the locality might suggest that sisyrids were usual members of the Santonian riparian biocenoses of northern Siberia.     

Further records of biting midges (Diptera: Ceratopogonidae) from Upper Cretaceous Burmese amber (Myanmar)

A new biting midge Archiculicoides andersoni sp. nov. from Upper Cretaceous Burmese amber is described and illustrated. An unknown male of Leptoconops myanmaricus Szadziewski, 2004 is described and an undetermined female of the genus Archiaustroconops and Austroconops in the collection of National Museums Scotland is reported. A key for the determination of 10 named species in 6 genera of biting midges reported from Burmese amber is also provided.     

Cyclostratigraphy and high-frequency carbon isotope fluctuations in Upper Cretaceous shallow-water carbonates, southern Italy

Abstract A detailed carbon isotope study has been carried out on a Santonian (Upper Cretaceous) carbonate platform succession that crops out at Monte Sant'Erasmo (southern Italy). Previous centimetre‐scale studies on this succession have shown that high‐frequency eustatic changes, resulting from the Earth's orbital fluctuations, controlled the hierarchical organization of the depositional and early diagenetic features in elementary cycles, bundles (groups of three to five elementary cycles) and superbundles (groups of three or four bundles). The elementary cycles, which correspond to single beds, suggest a control caused by Earth's precession; the bundles and superbundles record the short (≈ 100 kyr) and long (≈ 400 kyr) eccentricity periodicity respectively. The δ¹³C signal of the Monte Sant'Erasmo succession is cyclic in nature and may be considered to be a reliable proxy for the sedimentary evolution (and related sea‐level history) of the analysed sequence. The carbon isotope cyclicity is recorded at bundle and superbundle level, but it is not evident at the scale of the elementary cycles, at least with the sampling interval used in this study. Spectral analysis of the δ¹³C record shows two main peaks corresponding to the short‐ and long‐eccentricity periodicity, whereas the precession signal is not evident in the power spectrum. In addition, lithofacies analysis shows that, in each bundle (and superbundle), higher C isotope values occur in sediments characterized by marine cements, whereas lower values are normally found in more restricted deposits overprinted by early meteoric diagenesis. Early diagenesis, driven by periodic sea‐level fluctuations, developed in either shallow‐subtidal (marine diagenesis) or subaerial‐exposed (meteoric overprint) sedimentary environments and directly influenced the carbon isotope signature. As a consequence, the δ¹³C record at Monte Sant'Erasmo reflects high‐frequency climatic oscillations controlling both environmental and early diagenetic changes. The long‐term isotopic record is similar to that of contemporaneous pelagic sections in England and elsewhere in Italy. It is concluded that the δ¹³C signature of shallow‐water carbonates, such as those of Monte Sant'Erasmo, offers great potential for correlation with coeval sections, including those of the pelagic realm.     

羌塘地块西南缘上侏罗统-下白垩统海相地层的发现

通过1:5万区域地质调查,在青藏高原羌塘地块西南缘鸡夯地区原划上三叠统日干配错群中新识别出一套上侏罗统-下白垩统地层。本文根据该套地层的岩石组合以及古生物面貌特征,初步探讨了该套地层的沉积环境和沉积相特征,对其中发育的玄武岩夹层采用锆石U-Pb (LA-ICP-MS)同位素测年方法,获得其年龄为118.3±2.1Ma。在发育的生物碎屑灰岩夹层中采集了珊瑚、双壳类、腕足、腹足类化石,化石资料显示该套地层形成于晚侏罗世-早白垩世。这是首次在南羌塘地块发现该时期海相地层,这一发现证明南羌塘地块在晚侏罗世-早白垩世时期海水并未完全退出,而是局部发育海相三角洲。     

A new genus and species of soldier beetle from Upper Cretaceous Burmese amber (Coleoptera,Cantharidae, Malthininae)

A new Upper Cretaceous genus and species of soldier beetles, Archaeomalthodes rosetta gen. et sp. nov., is described and illustrated from an individual preserved in Upper Cretaceous (Cenomanian, ca. 99 Ma) amber from northern Myanmar. It is undoubtedly placed in extant subfamily Malthininae based on its small-sized body, somewhat abbreviated elytra and fusiform terminal maxillary palpomere, representing the oldest documented occurrence of Malthininae. It suggests that this subfamily is an ancient group, which originated at least in the earliest Late Cretaceous. Our discovery sheds light on the palaeodiversity of Cantharidae in the Late Mesozoic. Together with other previously reported fossil cantharids, it is likely that Malthininae has been fairly diverse during the early evolution of Cantharidae. On the other hand, a morphological similarity between Archaeomalthodes and Recent malthinines and the occurrence of flowering plants in the Burmese amber implies a potential flower-visiting behaviour of this fossil species.     

Dimorphism in Placenticeras mintoi from the Upper Cretaceous Bagh Beds, central India

The Upper Cretaceous Bagh Beds yield many biota of which ammonoids are particularly well known. Previously Bagh ammonoids were grouped into many genera and species within several families. The present study, however, shows that failure to recognize dimorphism and a wide range of interspecific variation within the single genus Placenticeras perhaps results in taxonomic oversplitting. Specific dimorphism in P. mintoi has been established.     

阿尔卑斯-喀尔巴阡上白垩统大洋红层特征与对比

在前人研究的基础上,从时代、岩性、古生物、沉积速率、沉积环境等方面对阿尔卑斯—喀尔巴阡地区的上白垩统大洋红层进行了详细对比,发现研究区内上白垩统大洋红层最早出露于Cenomanian期,最晚可延续至古近纪,且在Campanian期出露最为广泛,其岩性以灰岩、泥灰岩和含泥灰岩为主,生物化石以浮游有孔虫为主,沉积速率较低且在各地不尽相似,在CCD面上、下均可以出现,沉积环境一般是大陆边缘盆地、斜坡和大洋盆地等远洋、半远洋环境。通过比较分析,为进一步深入研究上白垩统大洋红层提供较为全面的基础资料。     

西藏南部上白垩统高分辨率全岩碳同位素地层学

西藏南部上白垩统半远洋沉积高分辨率碳、氧同位素实验结果显示：δ^13C值在Cenomanian末期正偏并形成正偏“高原”,从Turonian期开始总体呈现长期持续负偏,到Campanian早期负偏达到最低值。这种长期变化格局与世界有关地区的碳同位素偏移和同期全球海侵海退旋回型式匹配性甚好,印证了晚白垩世δ^13C值长期偏移趋势可作为大区域乃至全球海平面变化的指针。短期δ^13C值波动方面,Cenomanian末期、Turonian中一晚期、Turonian-Santonian界线时期、Campanian期都存在与世界相关地区的可比性,但Coniacian-Santonian期全球碳同位素偏移型式存在较大差异。     

First record of the subfamily Archinemestriinae in the family Nemestrinidae (Diptera: Brachycera) from Upper Cretaceous Burmese amber

Mesonemestrius caii gen. et sp. nov. is the first record of Archinemestriinae (Nemestrinidae) to be described from Upper Cretaceous Burmese amber. Mesonemestrius caii can be attributed to the subfamily Archinemestriinae by the following characters: M₁ ending posterior to the wing tip and supernumerary crossveins absent. Mesonemestrius is characterized by M₁ bifurcating after the conjunction of M₁₊₂₊₃ and a long straight R₁. The discovery not only adds to the diversity of tangle-veined flies in Burmese amber, but also represents the youngest record of the ancient subfamily Archinemestriinae.     

Late Cretaceous marine reptiles (Elasmosauridae and Mosasauridae) of the Chatham Islands, New Zealand

A new marine reptile record for the Upper Cretaceous of the Chatham Islands is described from the Takatika Grit. Incomplete mosasaur and plesiosaur remains represent the first record of marine reptiles from the Chatham Islands and wider New Zealand. Present among the myriad bones are elasmosaurid plesiosaurs and mosasaurine mosasaurs. This assemblage is comparable to the New Zealand marine reptile record and represents apex predators that flourished in a zone of upwelling in a Late Cretaceous southern high-latitude ecosystem.     

辽西上白垩统大兴庄组地层层序及时代

辽宁西部白垩系上统大兴庄组主要分布于锦州、义县地区,在朝阳波罗赤、阜新碱锅等地也有零星出露。除阜新等地区为中基性火山熔岩及火山碎屑岩外,均为中酸性、酸性火山熔岩、熔岩碎屑岩、火山碎屑岩、火山碎屑沉积岩及次火山岩。角度不整合覆于白垩系下统义县组、九佛堂组、沙海组之上,平行不整合覆于白垩系孙家湾组之上,K—Ar同位素年龄值为80．83Ma,属晚白垩世。该期火山活动以爆发—喷溢交替进行为特点,间有次火山岩侵入,活动强度微弱,分布局限。     

Further evidence of marine Cenomanian,lower Turonian and Maastrichtian in the Upper Benue basin of Nigeria (West Africa)

Field investigations in the Upper Benue rift basin of Nigeria highlight the necessity for a review of the Cenomanian-Turonian biostratigraphy of the area. Three ammonite zones of Vascoceras bulbosum (Reyment), Paravascoceras costatum (Reyment) and Pseudotissotia (Bauchioceras) nigeriensis (Woods) have been recognized at sections exposed at the quarry of the cement factory near the village of Ashaka. The sediments within the Vascoceras bulbosum zone also contain specimens of Exogyra olisiponensis (Sharpe), Kanabiceras septemseriatum (Cragin) and Epengonoceras dumbli (Cragin). These are all indicative of an uppermost Cenomanian age and reveal that at least the lower portion of the Gongila Formation as exposed at Ashaka is faunistically equivalent to the Pindiga Formation as exposed in the type section at Pindiga.The shales in the Gombe region in which Libycoceras ismaeli (Zittel) was found are probably part of the Maastrichtian Fika shales outcropping extensively in the northern part of the area. The discovery of Cyclolithes nov. sp. within Gombe sandstones at Dakiti near Kumo confirm that they are at least partially marine in origin and Maastrichtian in age. This could be considered as an additional evidence in favour of the presence of marine waters in the Upper Benue during the last part of the Cretaceous.