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   

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   

徐淮地区早白垩世丰山和蔡山高镁埃达克质岩:拆沉下地壳熔融的熔体与地幔橄榄岩的反应     

霍腾飞  杨德彬  师江朋  杨浩田  许文良  王枫  卢毅 《岩石学报》2018,34(6):1669-1684

徐淮地区丰山花岗闪长斑岩和蔡山石英闪长玢岩的岩石地球化学、Sr-Nd-Hf同位素和石榴石的矿物化学研究对探讨华北克拉通东南缘早白垩世高镁埃达克质岩的岩石成因和构造演化具有重要意义。结果表明,丰山花岗闪长斑岩和蔡山石英闪长玢岩具高SiO_2(60.98%～67.88%)、富Al_2O_3(14.37%～15.04%)以及高的Na_2O/K_2O比值(1.58～2.24)和Mg~#值(57～66)的特征;富集LILE(Rb、Ba、Sr)和LREE,亏损HFSE(Nb、Ta、Ti)和HREE,具有Pb正异常和弱的Eu异常;结合高的Sr含量(579×10~(-6)～778×10~(-6))以及Sr/Y(33～69)和(La/Yb)_N比值(8.63～13.7),低的Y(10.5×10~(-6)～17.8×10~(-6))和Yb含量(0.74×10~(-6)～1.17×10~(-6)),暗示它们属于高镁埃达克质岩。丰山和蔡山埃达克质岩石的初始~(87)Sr/~(86)Sr比值介于0.7079～0.7086之间,ε_(Nd)(t)值变化于-10.77～-7.18之间,t_(DM2)=1504～1793Ma;岩浆锆石的ε_(Hf)(t)值为-14.2～-5.3,t_(DM2)=2101～2898Ma。徐淮地区早白垩世利国、班井、夹沟高镁埃达克质岩石中岩浆锆石的ε_(Hf)(t)值分别介于-13.4～-7.0、-13.4～-7.9和-15.9～-4.5之间,它们的t_(DM2)分别变化于2248～2825Ma、2331～2824Ma和2030～3048Ma之间。徐淮地区丰山和蔡山高镁埃达克质岩的Sr-Nd-Hf同位素组成和丰山花岗闪长斑岩中铁铝榴石残留晶的存在,结合它们高的Pb同位素组成和继承锆石U-Pb年代学暗示,丰山和蔡山高镁埃达克质岩浆主要起源于俯冲断离的扬子克拉通石榴辉石岩相下地壳物质熔融的熔体与地幔橄榄岩的反应,同时有拆沉的华北克拉通基底物质的参与,形成于华北克拉通东部岩石圈减薄的伸展构造背景。  相似文献   

大兴安岭北段新林战备村地区早白垩世火成岩年代学、地球化学及大地构造意义     

王文东  杨华本  刘涛  马治忠  郑吉林  胡军海  魏小勇 《世界地质》2018,37(1):21-36

大兴安岭北段新林战备村地区广泛发育晚中生代火山岩及花岗岩体。LA-ICP-MS锆石U-Pb测得战备村花岗岩体侵位年龄为121.0±0.8 Ma,其周围出露的白音高老组流纹岩喷发年龄为136.9±1.3 Ma,二者均形成于早白垩世。地球化学特征上,二者均属于过铝质高钾钙碱性-钾玄质系列,高SiO_2,富K_2O、Na_2O,低Mg、Ti,微量元素富集大离子亲石元素Rb、K、Ba及LREE,亏损高场强元素Nb、Ta、Ti及HREE,轻重稀土明显分异((La/Yb)_N=11~23.2),具中等-弱的Eu负异常(δEu=0.35~0.82),二者具同源岩浆演化的特征。结合前人研究结果,新林战备村地区早白垩世火成岩形成于后造山或碰撞后的构造环境,代表了伸展的大地构造背景,这些火成岩产出可能与蒙古—鄂霍茨克洋中侏罗世至早白垩世闭合造山后的伸展作用有关。  相似文献   

黑龙江省勃利盆地东部坳陷下白垩统穆棱组古环境恢复     

刘帅  郭巍  李文强 《世界地质》2018,37(4):1309-1316

勃利盆地东部坳陷下白垩统穆棱组暗色泥岩发育,通过对勃利盆地Zk2钻井岩芯观察及对暗色泥岩样品进行稀土、微量元素含量变化的分析,恢复了穆棱组沉积时期的古环境。结果显示:研究区穆棱组沉积相以三角洲平原、三角洲前缘和半深湖沉积亚相为主,穆棱组沉积初期气候特征以温暖湿润为主,中期气候变为半湿半干,盐度增加但仍是淡水沉积环境,穆棱组中晚期气候由干旱炎热气候逐步变为温暖湿润气候。穆棱组沉积时期气候总体呈温暖湿润-半湿半干-温暖湿润变化的规律。  相似文献   

武夷山中段司前花岗岩体形成时代、地球化学特征及地质意义     

辛宇佳  李建华  董树文  张岳桥 《地球学报》2018,39(3):269-281

本文对武夷山中段的司前岩体进行了系统的岩石学、地球化学、年代学及Lu-Hf同位素研究。结果表明,司前岩体形成于(140±1)Ma,主要由黑云母二长花岗岩组成,富碱(K_2O+Na_2O=6.67 wt%~8.25 wt%),富钾(K_2O/Na_2O=1.16~2.41),A/CNK值介于1.01~1.25之间。岩体具有较高的∑REE(177.73×10~(-6)~427.88×10~(-6))、Zr+Nb+Y+Ce含量(262.6×10~(-6)~581.5×10~(-6))和Zr饱和温度(平均824°C),FeOt/MgO(3.06~3.93)和10 000×Ga/Al(2.64~3.28)比值均较高,属典型的铝质-过铝质A型花岗岩。岩体的锆石εHf(t)值均为负值(–18.6~–7.9),暗示其源于古老的地壳物质重熔。综合上述结果和区域背景推测,司前岩体的源岩为新元古代麻源群变质火山-碎屑岩,源岩可能经历早古生代和白垩纪两期熔融事件,地幔岩浆为花岗岩的形成提供了热源,但并未贡献物质,岩体的形成与古太平洋板块俯冲过程中因俯冲板片后撤诱发的弧后扩张作用有关。  相似文献   

Zircon U-Pb Geochronology,Geochemistry and Petrogenesis of Early Cretaceous A-type Granites in the Mikengshan Area,Southern Jiangxi ProvinceEI北大核心CSCD     

Liang H.  Guo H.  Wang Q.  Xiong X.  Ou Q.  Zeng J.  Gou G.  Hao L. 《大地构造与成矿学》2018,(4):746-758

In the Mikengshan-Yanbei area, a special region for the tin mineralization in South China, there are some Yanshanian granites and porphyries and associated porphyry tin deposits (e.g., Yanbei). Although the tin mineralization is closely associated with the granitoids magmatism, the age and petrogenesis of the granites remain controversial. The Mikengshan pluton, which intrudes into the rhyolitic tuff and pyroclastic rocks of the Upper Jurassic Jilongzhang Formation, is the largest one in Mikengshan-Yanbei area and mainly consists of K-feldspar bearing granites. In this study, we report new age and geochemical data for the Mikengshan K-feldspar bearing granites. LA-ICP-MS zircon U-Pb age dating shows that they were generated in the Early Cretaceous (~138 Ma). They have high SiO2 (74.42% to 76.69%), low Al2O3 (12.39% to 13.49%) and Mg# (11 to 19), and negative Eu, Sr and Ba anomalies, and are rich in potassium (most K2O/Na2O=1.37 to 1.94) and high field strength elements (HFSEs), and are weakly peraluminous (A/CNK=1.03 to 1.1) with high 10000×Ga/Al ratios (3.46 to 4.96) and slightly high zircon saturation temperatures (807 ℃ to 817 ℃), showing the characteristics of the typical A-type granites. Moreover, they have high Rb contents 842×10-6 to 1295×10-6, Rb/Sr (90 to 255) ratios and show rare earth elements (REE) tetrad effect, which are similar to those of high fractionated granites. Thus, we suggested that the Mikengshan K-feldspar bearing granites are high fractionated and aluminous A-type granite. Their slightly high εNd(t) values (-3.4 to -4.6) indicate that the mantle components should have played a role during their formation. Taking into account regional igneous rocks and tectonic setting data, we suggest that the Mikengshan K-bearing granites were formed in an extensional setting, which was probably related to the roll-back of the subducted Paleo-Pacific plate. © 2018, Science Press. All right reserved.  相似文献