浙江新昌早白垩世木化石新材料及内含真菌菌丝化石     

朱志鹏  李丰硕  谢奥伟  田宁  王永栋 《地质学报》2018,92(6):1149-1162

浙江新昌下白垩统馆头组是我国南方地区为数不多的白垩纪木化石产出层位。本文报道了新昌地区馆头组木化石新材料及其内含真菌菌丝化石。木化石具明显生长轮,管胞径壁纹孔南洋杉式(多数单列、椭圆形、紧挤排列,偶见双列互生排列);交叉场纹孔南洋杉式;木射线单列式,多数2~11个细胞高。当前木化石新材料具有与现生南洋杉科植物相类似的木材解剖特征,显示其应归入贝壳杉型木属(Agathoxylon Hartig)。鉴于该类型木化石的分类现状仍有待厘清,将其定为Agathoxylonsp.。木化石内含真菌菌丝化石,管状,具横隔,平直或弯曲,常以不同角度分叉,菌丝壁光滑,具典型的锁状联合,属于担子菌类。当前木化石木材组织具有明显的木材腐朽特征,与现代真菌造成的木材白腐一致,推断此真菌化石为木材白腐菌。新昌地区贝壳杉型木属木化石新材料的发现进一步丰富了馆头组木化石的多样性,有助于增进对南方地区早白垩世植物群组成特征的认识。当前真菌菌丝化石是我国南方地区首次发现白垩纪担子菌化石,为探究白垩纪时期森林生态系统真菌与植物的相互作用提供了新的化石证据。  相似文献   

Middle Jurassic–Early Cretaceous tectonic evolution of the Bayanhushuo area,southern Great Xing’an Range,NE China: constraints from zircon U–Pb geochronological and geochemical data of volcanic and subvolcanic rocks     

Qing-Bin Guan  Bin Wang  Xiong Wang  Xing-An Wang  Qiang Shi 《International Geology Review》2018,60(15):1883-1905

This study presents new zircon U–Pb geochronology, geochemistry, and zircon Hf isotopic data of volcanic and subvolcanic rocks that crop out in the Bayanhushuo area of the southern Great Xing’an Range (GXR) of NE China. These data provide insights into the tectonic evolution of this area during the late Mesozoic and constrain the evolution of the Mongol–Okhotsk Ocean. Combining these new ages with previously published data suggests that the late Mesozoic volcanism occurred in two distinct episodes: Early–Middle Jurassic (176–173 Ma) and Late Jurassic–Early Cretaceous (151–138 Ma). The Early–Middle Jurassic dacite porphyry belongs to high-K calc-alkaline series, showing the features of I-type igneous rock. This unit has zircon ε_Hf(t) values from +4.06 to +11.62 that yield two-stage model ages (T_DM2) from 959 to 481 Ma. The geochemistry of the dacite porphyry is indicative of formation in a volcanic arc tectonic setting, and it is derived from a primary magma generated by the partial melting of juvenile mafic crustal material. The Late Jurassic–Early Cretaceous volcanic rocks belong to high-K calc-alkaline or shoshonite series and have A₂-type affinities. These volcanics have ε_Hf(t) and T_DM2 values from +5.00 to +8.93 and from 879 to 627 Ma, respectively. The geochemistry of these Late Jurassic–Early Cretaceous volcanic rocks is indicative of formation in a post-collisional extensional environment, and they formed from primary magmas generated by the partial melting of juvenile mafic lower crust. The discovery of late Mesozoic volcanic and subvolcanic rocks within the southern GXR indicates that this region was in volcanic arc and extensional tectonic settings during the Early–Middle Jurassic and the Late Jurassic–Early Cretaceous, respectively. This indicates that the Mongol–Okhotsk oceanic plate was undergoing subduction during the Early–Middle Jurassic, and this ocean adjacent to the GXR may have closed by the Late Middle Jurassic–Early Late Jurassic.  相似文献   

Early Cretaceous K-rich rhyolites from the Duolong Cu–Au deposit,southern Qiangtang,China: evidence for crustal growth     

Wei Wang  Cai Li  Jian-Jun Fan  Wei Xu  Yu-Chao Dong 《International Geology Review》2018,60(9):1098-1115

We report new zircon U–Pb age, Hf isotopic, and major and trace element data for rhyolites from the Duolong Ore Concentration Area of the Southern Qiangtang Terrane. Building on previous studies, we constrain the tectonic setting and propose a model to explain the geodynamics and crustal growth during regional magmatism in the Early Cretaceous. The analysed rhyolites yield laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U–Pb ages of 115 and 118 Ma. The rocks are K-rich (K₂O = 6.66–9.93 wt.%; K₂O/Na₂O = 8.2–19.7 wt.%), alkaline and peraluminous (A/CNK = 1.02–1.46), and are characterized by high SiO₂ contents (72.8–78.8 wt.%) similar to highly fractionated I-type granites. Fractionation of Fe–Ti oxides, plagioclase, hornblende, Ti-bearing phases, apatite, monazite, allanite and zircon contributed to the variations in major and trace element chemistry. High K₂O contents are likely due to partial melting of the continental crust. The samples have positive zircon εHf(t) values ranging from +7.1 to +11.2. These features, together with young zircon Hf crustal model ages of 489–721 Ma, indicate that the K-rich rhyolites were derived from juvenile lower crust with an input of a mantle-derived component. We suggest that the Early Cretaceous K-rich rhyolites formed in a continental arc setting during northward subduction of Bangong Co–Nujiang oceanic lithosphere. Basaltic magma underplating was responsible for vertical crustal growth, triggered by slab roll-back in the Duolong Ore Concentration Area in the Early Cretaceous.  相似文献   

Plant assemblage from Opole,southern Poland: New data on Late Cretaceous vegetation of the northern part of the European Province     

Bartosz J. Płachno  Agata Jurkowska  Grzegorz Pacyna  Elżbieta Worobiec  Przemysław Gedl  Ewa Świerczewska-Gładysz 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(2):159-170

This paper presents the results of studies on plant macroremains found in the upper Turonian of the Folwark Quarry, Opole, Poland, associated with palynological studies of the host rocks. In addition to a few macrofossils (gymnosperm wood, conifer Geinitzia reichenbachii and fern ?Didymosorus) rich sporomorphs (bryophyte, lycopod and fern spores, conifer and angiosperm pollen grains) and marine palynomorphs (mainly dinoflagellate cysts) were recorded. The palynological analysis revealed that the vegetation on the neighbouring land (the East Sudetic Island) in the late Turonian was much more diverse than could be reconstructed based on only macrofossil remains. The latter are taxonomically restricted and dominated by one gymnosperm species (Geinitzia reichenbachii), which make them similar to most neighbouring, coeval Central European assemblages. Its over representation is, thus, a result of taphonomy.  相似文献   

Alpine metamorphism of low-grade schists from the Slavonian Mountains (Croatia): new P-T and geochronological constraints     

Dražen Balen  Hans-Joachim Massonne  Iva Lihter 《International Geology Review》2018,60(3):288-304

Low-grade schists from the Slavonian Mountains (Tisia Mega-Unit, Mt Papuk, Croatia), previously assigned to Precambrian to Lower Palaeozoic metamorphism, have been subjected to geochemical investigations, P-T modelling, and in situ age dating of monazite. The studied fine-grained metasediments consist of chlorite (5–15 vol.%), K white-mica (40–55 vol.%), quartz (20–35 vol.%), feldspar (albite 15–20 vol.%), opaques (<2 vol.%), and accessory minerals. According to their whole-rock geochemistry, the detritus of the former sediments came from upper crustal felsic rocks as they occur, for instance, at Mt Papuk. The schists show a complex microtectonic fabric, including well-developed schistosity systems. P-T pseudosections in the system MnNCKFMASHTO, constructed for typical schists of the study area, resulted in peak P-T conditions of 445–465 °C and 4.6–6.0 kbar for a sample from Kutjevo (eastern part of the study area) and 450–460 °C and 5.2–6.0 for a Vranovo sample (western part). Electron microprobe (EMP) dating of monazite in the schists gave a weighted average age of 109.0 ± 13.1 Ma (2σ) eventually with three subgroups of ages at 225 ± 63 (two analyses), 114 ± 24 and 83 ± 22 Ma. We conclude that the metamorphism of the studied schists at depths of c. 20 km is due to an Alpine collisional event.  相似文献   

A new tree fern stem,Tempskya zhangii sp. nov. (Tempskyaceae) from the Cretaceous of Northeast China     

《Cretaceous Research》2018

A new Cretaceous tree fern species from the family Tempskyaceae, Tempskya zhangii sp. nov., from Keshan County, Heilongjiang Province, Northeast China, is described based on silicified fragments. The species is characterized by dichotomizing stems embedded in a matrix of adventitious roots, together forming a solid and compact false trunk. The dorsiventral stems are composed of solenosteles, and their internodes are short with 2–3 (rarely 4) leaf traces. A three-layered cortex includes a sclerenchymatous outer zone, parenchymatous middle zone, and an inner zone composed of sclerenchyma band and parenchyma cells. The pith consists of a parenchymatous outer zone and sclerenchymatous inner zone. The petiole has a single C- or U-shaped vascular strand. The adventitious root has diarch xylem surrounded by an inner sclerenchymatous and an outer parenchymatous cortex. In possessing these characters, T. zhangii is more similar to T. wyomingensis from the Cretaceous of North America than to other species of Tempskya. However, the Chinese species distinctly differs from T. wyomingensis in having a sclerenchymatous outer cortex, parenchymatous middle cortex, and sparse parenchyma in the xylem. It is the first record of Tempskya from China and the fourth from Asia. This species, together with Cyatheaceae, Osmundaceae, Cycadeoidaceae, and conifers found in the same region constituted the plant community at the time.  相似文献   

Discovery of the largest pterosaur from South America     

《Cretaceous Research》2018

A giant humerus (450 mm total length) belonging to one of the largest pterosaur recorded in South America is described. The specimen (UNCUYO-LD 350) was discovered in the Upper Cretaceous (upper Coniacian – lower Santonian) Plottier Formation of the Mendoza Province, northern Neuquén Basin, Argentina. It was found associated with a smaller pterosaur specimen represented by around thirty postcranial bones. The specimen is assigned to Tapejaroidea and show characters of both Tapejaridae and Azhdarchidae. Based on comparisions with other Azdharchidae species, a wingspan of 9.1 m is estimated for UNCUYO-LD 350, showing that giant pterosaurs were present in South America during the Upper Cretaceous.  相似文献   

A new species of Anteophthalmosuchus (Crocodylomorpha,Goniopholididae) from the Lower Cretaceous of the Isle of Wight,United Kingdom,and a review of the genus     

《Cretaceous Research》2018

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Zurupleuropholis gen. nov. (Teleostei,Albian, Argentina), first pleuropholids from the Cretaceous of South America     

《Cretaceous Research》2018

Although the Cretaceous is characterized by a rich fish diversity, Cretaceous continental fishes from Gondwana are poorly known and comparatively scarce. Among these fishes, the family Pleuropholidae is only known by a few species relatively poorly preserved, from the Middle Jurassic to Lower Cretaceous of Europe, Africa, North America, and South America. In this paper, two new species of the pleuropholid new genus Zurupleuropholis are described, Z. quijadensis gen. et sp. nov. and Z. decollavi gen. et sp. nov. The new fishes were recovered in the Lower Cretaceous lacustrine Lagarcito Formation of central-west Argentina. This taxon constitutes a relevant finding considering that the representation of the family Pleuropholidae is rare worldwide. Zurupleuropholis gen. nov. appears to be the youngest known member of Pleuropholidae, and it represents the second record of the family in South America and the first record in the Cretaceous of the continent.  相似文献   

Laurasian ancestors and “Gondwanan” descendants of Rotoitidae (Hymenoptera: Chalcidoidea): What a review of Late Cretaceous Baeomorpha revealed     

《Cretaceous Research》2018

Baeomorphinae Yoshimoto, 1975, based on Baeomorpha Brues, 1937, is transferred from Tetracampidae Förster, 1856 and recognized as a junior synonym of Rotoitidae Bouček and Noyes, 1987 (Hymenoptera: Chalcidoidea) syn. nov. following ICZN (1999) article 35.5. Inclusions in Taimyr amber (84–100 Ma) assigned to Baeomorpha are reviewed and the following eleven new species, all of Gumovsky, are described: B. avamica sp. nov., B. baikurenis sp. nov., B. bianellus sp. nov., B. caeleps sp. nov., B. gracilis sp. nov., B. ingens sp. nov., B. quattorduo sp. nov., B. quattoruno sp. nov., B. popovi sp. nov., B. yantardakh sp. nov., and B. zherikhini sp. nov. The recognized species are differentiated in separate keys to females and males and illustrated through microphotography. Two of four previously described Baeomorpha species from Campanian Canadian amber are synonymized: B. distincta Yoshimoto and B. elongata Yoshimoto under B. ovatata Yoshimoto (syn. nov.). One enigmatic rotoitid inclusion, which differs from Baeomorpha species in the possession of very short stigmal vein, is described as Taimyromorpha pusilla Gumovsky gen. et sp. nov. Inclusions containing specimens identified as Baeomorpha and Taimyromorpha are found in amber from Taimyr and Canada that originated from Laurasia, not Gondwana. Two Realms are newly proposed to recognize different Cretaceous faunal elements, a more northern Baeomorpha Realm that is characterized by a temperate or warm temperate climate and very abundant aphid fossils, and the Isoptera Realm, an opposing southward territory with a warmer climate and common termite but rare aphid fossils. The newly described fossils indicate the southern hemisphere distribution of extant Rotoitidae is relictual with the pattern observed being formed at least in part by extinction events, though distributions of the only two extant rotoitid genera, Rotoita Bouček and Noyes, 1987 (New Zealand) and Chiloe Gibson and Huber, 2000 (small area in the southern Chile) may have been more extensive in the past. Both of known regions of extant Rotoitidae have highly suppressed ant faunas, which may suggest that their survival there depended on low biocenotic pressure by ants, perhaps as low as is hypothesized for the Late Cretaceous. The Canadian amber genera Distylopus Yoshimoto, 1975 (Distylopinae) and Bouceklytus Yoshimoto, 1975 (Bouceklytinae) are excluded from Tetracampidae and regarded as Chalcidoidea incertae sedis.  相似文献