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802.
Charnockites sensu lato(charnockite-enderbite series) are lower crustal felsic rocks typically characterised by the presence of anhydrous minerals including orthopyroxene and garnet.They either represent dry(H2O-poor) felsic magmas that are emplaced in the lower crust or granitic intrusions that have been dehydrated during a subsequent granulite facies metamorphic event.In the first case,postmagmatic high-temperature recrystallisation may result in widespread metamorphic granulite microstructures, superimposed or replacing the magmatic microstructures.Despite recrystallisation,magmatic remnants may still be found,notably in the form of melt-related microstructures such as melt inclusions. For both magmatic charnockites and dehydrated granites,subsequent fluid-mineral interaction at intergrain boundaries during retrogradation are documented by microstructures including K-feldspar microveins and myrmekites.They indicate that a large quantity of low-H2O activity salt-rich brines,were present(together with CO2 under immiscible conditions) in the lower crust. 相似文献
803.
列举并尝试对比了非洲早白垩世脊椎动物化石的主要产地。晚侏罗世(坦桑尼亚的敦达古鲁基默里奇期提塘期)至白垩纪最早期(南非的阿尔戈阿盆地凡兰吟期)的组合中含有剑龙、腕龙和梁龙,到前阿普特期(欧特里沃期巴列姆期?)被另一组合所取代。这一更年轻的组合中含有重爪龙亚科棘龙类、大头鳄类鳄鱼Sarcosuchus以及大型禽龙,它们主要来自尼日尔(ElRhaz组和喀麦隆(Koum组),部分来自利比亚(Cabao组)和突尼斯(Douiret组),后两组中还含有鲨鱼Priohybodus ar ambourgi。阿普特期(?)至早阿尔必期组合中仍含有禽龙,但是棘龙科棘龙类取代了重爪龙亚科。早塞诺曼期组合(Bahariya,Kem Kem)以恐龙Spinosaurus、Carcharodonto saurus,鲨鱼(Onchopris tisnumidus)和鳄鱼(利比亚鳄类、无棘腔鳄类)为特征。由此可知,中非的一些原先被认为是早白垩世的地层(坦桑尼亚的Galula组、马拉维的含恐龙层)为晚白垩世。脊椎动物化石在非洲陆相地层的对比中具有重要作用。 相似文献
804.
南阿尔金茫崖地区花岗岩类锆石SHRIMPU-Pb定年、Lu-Hf同位素特征及岩石成因 总被引:12,自引:4,他引:8
南阿尔金茫崖地区早古生代花岗岩锆石SHRIMP U-Pb定年结果表明,阿克提山花岗岩为264±1Ma,柴水沟花岗岩分别为404±5Ma、406±4Ma,其中的辉绿岩为454±4Ma,常春沟花岗岩分别为411±5Ma、406±3Ma,茫崖镇北石英闪长岩为466±5Ma,阿卡龙山花岗岩为469±6Ma。锆石Lu-Hf同位素分析表明,εHf(t)值大多数为正值,少数继承性锆石为负值,反映了它们的源岩以新生地壳为主,同时,也混有少量的古大陆壳的成分。结合区域地质特征和各岩体的岩石地球化学特征,将南阿尔金茫崖地区早古生代花岗质岩浆活动划分为3期,第一期(465~469Ma)岩石组合为石英闪长岩+花岗闪长岩+花岗岩,具有岛弧火成岩的地球化学属性,其形成可能与洋壳的俯冲作用有关;第二期(404~411Ma)岩石组合为花岗闪长岩+二长花岗岩+正长花岗岩,具有A型花岗岩的地球化学特征,可能与板块碰撞后造山带块体均衡调整有关,第三期(264Ma)岩石组合为石英闪长岩+二长花岗岩+正长花岗岩,也具有I型花岗岩的特征,可能与阿尔金断裂的活动有关。 相似文献
805.
A new partial specimen of Zhenyuanopterus from the Lower Cretaceous Yixian Formation of Beipiao city, Liaoning Province is described. This specimen is slightly larger than half the size of the holotype. Although it is not complete, it provides new information on Zhenyuanopterus both in taxonomy and ontogeny: the total number of the caudal vertebrae is 15; the forelimb is more robust than the hindlimb; the growth rate of the humerus and femur is constant, and their ratio is about 1. Compared with the holotype, the scapula and coracoid grow faster than the humerus and the femur. The scapula and coracoid may slow their growth rate after a certain ontogenetic stage. The pectoral girdle, robust forelimb and weak hindlimb of the new material(XHPM1088) together with data from the holotype of Zhenyuanopterus indicate that this taxon spent less time on land than in the sky or other ecological niches such as forests and cliffs. 相似文献
806.
ZHU Dagang MENG Xian’gang SHAO Zhaogang YANG Chaobin HAN Jian’en YU Ji MENG Qingwei Lü Rongping 《《地质学报》英文版》2010,84(2):280-295
<正>Based on field geological survey,stratigraphic section measurement and indoor comprehensive investigation,the Zanda Basin's tectonic location in the Himalaya Plate was ascertained,and the formation and evolution of the Zanda Basin during the Pliocene to Early Pleistocene was classified as six stages:(a) primary rift-faulting stage,(b) quick rift-faulting Stage,(c) intensive rift-faulting stage,(d) stasis stage,(e) secondary rift-faulting stage,and(f) secondary quick rift-faulting stage.Based on this six-staged formation-evolution theory of the Zanda Basin,the upwelling process of the Western Himalaya Mountains from the Pliocene to Early Pleistocene was classified as the following five stages:(a) slow upwelling stage(5.4-4.4 Ma),(b) mid-velocity upwelling stage(4.4-3.5 Ma),(c) quick upwelling stage(3.5-3.2 Ma),(d) upwelling-ceasing stage(3.2-2.7 Ma), and(e) quick upwelling stage(2.7 Ma).Research has shown that in the duration from the Early Pliocene(4.7 Ma) to the End of Pliocene(2.67 Ma),which lasted 2.03 million years,the Himalaya Mountains had uplifted 1500 m at a velocity of 0.74 mm/a;this belongs to a mid-velocity upwelling. During the 1.31 million years in the Early Stage of the Early Pleistocene,the Himalaya Mountains had risen up another 1500 m at a velocity of 1.15 mm/a;this is a rather quick upwelling.All of these data have shown that the upwelling of the Western Himalaya Mountains is along a complicated process with multi-stages,multi-velocities,and non-uniformitarian features. 相似文献
807.
A New Boreopterid Pterodactyloid Pterosaur from the Early Cretaceous Yixian Formation of Liaoning Province, Northeastern China 总被引:2,自引:0,他引:2
Lü Junchang 《《地质学报》英文版》2010,84(2):241-246
<正>A new boreopterid pterosaur:Zhenyuanopterus longirostris gen.et sp.nov.from the Yixian Formation of western Liaoning is erected,based on the complete skeleton with a skull and lower jaws preserved.It is characterized by:a large boreopterid pterosaur with a high number of teeth,where the anterior teeth are much larger than posterior ones;the length of the dorsal + sacral vertebrae is nearly half the length of the skull;ratio of the length of the humerus to metacarpal IV is approximately 91%and the,humerus,femur and third wing phalanx are all equal in length and the feet are specially small.It represents the largest boroepterid pterosaur discovered from western Liaoning and its surrounding areas so far 相似文献
808.
María NAJARRO Enrique PE?ALVER Ricardo PéREZ-DE LA FUENTE Jaime ORTEGA-BLANCO Cesar MENOR-SALVáN Eduardo BARRóN Carmen SORIANO Idoia ROSALES Rafael LóPEZ DEL VALLE Francisco VELASCO Fernando TORNOS Véronique DAVIERO-GOMEZ Bernard GOMEZ Xavier DELCLòS 《《地质学报》英文版》2010,84(4):959-976
<正>El Soplao outcrop,an Early Cretaceous amber deposit recently discovered in northern Spain (Cantabria),has been shown to be the largest site of amber with arthropod inclusions that has been found in Spain so far.Relevant data provided herein for biogeochemistry of the amber,palynology,taphonomy and arthropod bioinclusions complement those previously published.This set of data suggests at least two botanical sources for the amber of El Soplao deposit.The first(type A amber)strongly supports a source related to Cheirolepidiaceae,and the second(type B amber)shows non-specific conifer biomarkers.Comparison of molecular composition of type A amber with Frenelopsis leaves(Cheirolepidiaceae)strongly suggests a biochemical affinity and a common botanical origin.A preliminary palynological study indicates a regional high taxonomical diversity,mainly of pteridophyte spores and gymnosperm pollen grains.According to the preliminary palynological data,the region was inhabited by conifer forests adapted to a dry season under a subtropical climate.The abundant charcoalified wood associated with the amber in the same beds is evidence of paleofires that most likely promoted both the resin production and an intensive erosion of the litter,and subsequent great accumulation of amber plus plant cuticles.In addition,for the first time in the fossil record, charcoalified plant fibers as bioinclusions in amber are reported.Other relevant taphonomic data are the exceptional presence of serpulids and bryozoans on the surfaces of some amber pieces indicating both a long exposure on marine or brackish-water and a mixed assemblage of amber.Lastly,new findings of insect bioinclusions,some of them uncommon in the fossil record or showing remarkable adaptations,are reported.In conclusion,a documented scenario for the origin of the El Soplao amber outcrop is provided. 相似文献
809.
The International Maritime Organisation's (IMO) ban on the use of tributyltin in antifouling paints has inevitability increased the use of old fashioned antifoulants and/or the development of new paints containing 'booster biocides'. These newer paints are intended to be environmentally less harmful, however the broader environmental effects of these 'booster biocides' are poorly known. Germination and growth inhibition tests using the marine macroalga, Hormosira banksii (Turner) Desicaine were conducted to evaluate the toxicity of four new antifouling biocides in relation to tributyltin-oxide (TBTO). Each of the biocides significantly inhibited germination and growth of Hormosira banksii spores. Toxicity was in increasing order: diuron < zineb < seanine 211< zinc pyrithione < TBTO. However, the lack of knowledge on partitioning in the environment makes it difficult to make a full assessment on whether the four biocides tested offer an advantage over organotin paints in terms of environmental impact. 相似文献
810.
Spatial and temporal distribution of dissolved/dispersed aromatic hydrocarbons in seawater in the area affected by the Prestige oil spill 总被引:7,自引:0,他引:7
González JJ Viñas L Franco MA Fumega J Soriano JA Grueiro G Muniategui S López-Mahía P Prada D Bayona JM Alzaga R Albaigés J 《Marine pollution bulletin》2006,53(5-7):250-259
Seawater samples collected at three depths from 68 stations along the Northern Spanish coast were analysed for dissolved/dispersed petroleum aromatic hydrocarbons by UV-fluorescence and for 25 individual compounds by GC-MS. Sampling was performed in December 2002, just after the Prestige oil spill, and in February-March and September 2003. Higher concentrations of total aromatic hydrocarbons were found at all depths in the samples collected during December 2002 off the Galicia coast, with levels ranging between 0.19 and 28.8 microg/L eq. oil (0.1-4.8 microg/L chrysene eq.). These values decreased in the following cruises, till <0.05-2.86 microg/L oil eq. (av. 0.23 microg/L chrysene eq.) in September 2003, possibly representing the background levels for the region. However, in the Cantabrian coast they were still high at the surface in the March cruise, probably by the late arrival of the fuel-oil to this area. Some coastal hot spots were also identified, with values up to 29.2 microg/L fuel-oil eq., close to river mouths and urban areas. The individual PAH distributions in the December 2002 sampling off-Galicia were dominated by alkyl-naphthalene derivatives, consistently with the pattern distribution shown by the fuel-oil water accommodated fraction. The higher concentrations were found in the subsurface samples along the Costa da Morte, the area most heavily affected by the spill (av. 0.46 microg/L Sigma16 PAHs). The rest of the samples collected in other areas exhibited lower concentrations and a more even distribution of 2-4 ring PAHs, that ranged from 0.09 to 0.37 microg/L (av. 0.15 microg/L Sigma16 PAHs), with decreasing trends offshore and downward the water column. In September 2003, the values were rather uniform, averaging 0.09 microg/L (Sigma16 PAHs). 相似文献