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61.
义县盆地早白垩世义县组为一套火山-沉积岩系,沉积层中多含凝灰质成分。为了解沉积期火山活动对沉积层产生的影响,对砖城子层火山碎屑泥灰岩(火山事件层)和纹层状泥灰岩夹层、大康堡层纹层状泥灰岩进行岩石学和地球化学的研究。研究表明:火山事件层中含大量的火山碎屑(20%±),其他各层均含凝灰质成份。样品中主量元素Ca O、Mg O和Si O_2含量较高,Si O_2含量变化较大,Al_2O_3含量较低;微量元素与上地壳(UCC)元素比值多小于1,大多数微量元素(Rb、Th、Nb、REE等)处于亏损状态,火山事件层富集Li、Sc、As、Sr和Ag元素。沉积期火山活动对沉积层中Si O_2和K_2O含量影响较大,并可能导致As元素富集。火山事件层样品化学风化指数(CIW)在82~91之间,呈逐渐增加的趋势,指示风化作用强烈。 相似文献
62.
Edmund A. Jarzembowski B. Wang Y. Fang H. Zhang 《Proceedings of the Geologists' Association. Geologists' Association》2014
The first malacostracan crustacean is described and named from the English Wealden, Cymothoidana websteri gen. et sp. nov., a Cirolana-like, cymothoidan isopod. The problem of homoplastic convergence in somatic characters is discussed, and Cymothoidana is treated as a collective group (morphotaxon) under the International Code of Zoological Nomenclature for cirolanoid and cymothooid fossils which cannot be assigned to natural taxa on preservational grounds. The palaeoecology of early Cretaceous peracaridan malacostracans is considered, including the spelaeogriphaceans Liaoningogriphus from China (Jehol biota), and Spinogriphus from Spain (Las Hoyas Konservat-lagerstätte). There were probably no true stygobites, Spinogriphus perhaps a crenobite, but the colonisation of reduced salinity environments (Cymothoidana) and freshwater lakes (Liaoningogriphus) had commenced. 相似文献
63.
We describe a new species of Early Cretaceous bird from the Yixian Formation of Liaoning Province. Xinghaiornis lini gen. et sp. nov. is relatively large and characterized by a long, toothless rostrum and an elevated pedal digit I. The design of the skull and feet suggests that this bird was likely a mud-prober. This discovery provides strong support indicating that this avian trophic specialization originated at least 125 million years ago. 相似文献
64.
沉积岩的地球化学特征蕴含了大量的地质信息,对于沉积环境的重塑及物源研究具有重要意义。通过对辽宁北部秀水盆地秀D1井义县组泥岩样品常量、微量及稀土元素等地球化学特征的研究表明:泥岩样品轻稀土元素富集,重稀土元素亏损严重,配分曲线"右倾",可见中等Eu负异常和微弱的Ce负异常,指示稳定的上地壳物源注入。盆地北东—东部的侏罗系、二叠系酸性侵入岩与义县组沉积岩具有较好的亲缘性,可能为其主要物源,源区构造背景主要为活动大陆边缘。B、Sr/Ba、La_N/Sm_N、V/(V+Ni)、Fe2+/Fe3+、Cu/Zn及Ceanom等地球化学指标表明义县组沉积时期为淡水环境,古沉积环境为深水还原环境。 相似文献
65.
The fossil snakefly family Baissopteridae from the Lower Cretaceous (upper Barremian) of the Yixian Formation of Liaoning Province, China is reviewed. Two genera and five species of Baissopteridae are recorded, including a new genus, namely Microbaissoptera gen. nov., and three new species, i.e., Baissoptera bicolor sp. nov., Baissoptera sinica sp. nov., and Microbaissoptera monosticha sp. nov. Moreover, Baissoptera euneura Ren, 1997 is herein treated as a new junior synonymy of Baissoptera grandis Ren in Ren et al., 1995. Baissoptera minima Ponomarenko, 1993 is transferred to the presently described new genus Microbaissoptera gen. nov. based on the small body-size and the presence of a single gradate series of crossveins in radial and medial areas of posterior part of both fore- and hind wings. A key to genera of Baissopteridae is provided. 相似文献
66.
67.
Three eusauropod teeth (SDUST-V1064, PMOL-AD00176, PMOL-ADt0005) are reported from the Lower Cretaceous Yixian Formation of Ningcheng, southeastern Inner Mongolia, China. Two of them (SDUST-V1064, PMOL-AD00176) are assigned to early-diverging titanosauriforms in having slightly mesiodistal expansion at the base of the tooth crown, a slenderness index value >2.0 and <4.0, and D-shaped cross section. Furthermore, SDUST-V1064 and PMOL-AD00176 are referred as an Euhelopus-like titanosauriform on the basis of having a sub-circular boss on the lingual surface and an asymmetrical crown-root margin which slants apically, respectively. 相似文献
68.
JI Shu''an JI Qiang School of Earth Space Sciences Peking University Beijing Institute of Geology Chinese Academy of Geological Sciences Beijing 《《地质学报》英文版》2004,78(4):897-906
The postcranial skeleton of a new specimen of the long-tailed lizard Dalinghosaurus longidigitus was excavated from the Yixian Formation in Lingyuan, western Liaoning. The new specimen provides more anatomical information about this species, especially about the anterior dorsal vertebrae, shoulder girdle and forelimbs. This lizard can be included within the clade Scleroglossa by its 27 or more presacrals, moderately long pubis, and gently notched distal end of tibia. But the detailed systematic position for this taxon remains undetermined. The features of the much longer hind limbs and pes compared with forelimbs and manus, metatarsal Ⅳ longer than Ⅲ, pedal phalanges robust, and penultimate phalanx not longer than other phalanges etc. suggest that this lizard was a running and ground swelling animal. 相似文献
69.
70.