黑河市五道沟地区早二叠世A型花岗岩成因   总被引：1，自引：0，他引：1  

郭奎城  张文龙  杨晓平  王磊  史冬岩  于海涛  苏航 《吉林大学学报(地球科学版)》2011,41(4):1077-1083

根据岩石学、岩石化学、地球化学及同位素等特征,对黑河市五道沟地区早二叠世碱长花岗岩进行了构造成因研究。该套岩石具高硅、富碱、低钙镁、偏铝质-过铝质特点,且富Rb、Th、K等大离子亲石元素,相对亏损Ba、Sr、P、Ti、Nb等元素,稀土元素具有典型的海鸥式分配样式,总体具有典型A型花岗岩特征;其形成于额尔古纳—兴安地块与松嫩—张广才岭地块挤压拼贴后的伸展环境。黑河市五道沟地区A型花岗岩的最新厘定对该地区晚古生代构造演化的研究及区域成矿规律的探讨具有重要意义。  相似文献   

Palynology of organic beds below Devensian glacigenic sediments at Pen-y-bryn,Gwynedd, North Wales     

Frank M. Chambers  Kenneth Addison  Jeffrey J. Blackford  Martin J. Edge 《第四纪科学杂志》1995,10(2):157-173

Pollen diagrams from organic facies overlain by glacigenic sediments at Pen-y-bryn, North Wales (53°7′N, 4°16′W), suggest that it is the first locality in the British Isles to provide evidence for several Devensian interstadials prior to Devensian stadial glaciation(s). The evidence is not, however, unequivocal. At least two main episodes of organic sedimentation are indicated, separated by an interval of uncertain duration. One eposide records a Pinus-Picea-Betula forest. A second, possibly later, event, with tree pollen less than 10% of total land pollen (TLP), suggests a cool, largely unforested environment. A third episode, with tree pollen up to 25% of TLP, may be related to the latter or be of intermediate age, whereas a fourth and later episode of organic accumulation may be of reworked material. Radiocarbon dating of organic deposits and of a wood macrofossil enclosed in basal till is inconclusive, as is preliminary uranium-series dating. The principal biogenic episodes may correlate with Oxygen Isotope Substages 5c and 5a, but as the pollen records reflect facies floras, the correlation remains tentative; it is also possible that other temperate periods are recorded. Further resolution of the chronostratigraphy is required to help clarify the problematic correlation of interstadial and stadial events in northwest Europe and to correlate more accurately the biogenic and glacigenic facies at Pen-y-bryn with their Pleistocene equivalents elsewhere.  相似文献   

Androecium of Archaefructus, the Late Jurassic Angiosperms from Western Liaoning, China     

SUN Ge  ZHENG Shaolin  SUN Chunlin  SUN Yuewu  David L.DILCHER  MIAO Yuyan 《世界地质(英文版)》2002,5(1)

Androecium of the earliest known flowering plant Archaefructus liaoningensis was found from the Upper Jurassic Jianshangou Formation of western Liaoning, China. The androecium consists of numerous stamens bearing in pair on the reproductive axes below conduplicate carpels. The stamens are composed of a short filament and basifixed anther for each. Monosulcate pollen in situ are found from the anthers. The characters of the androecium reveals that Archaefructus are probably protandrous, and the paired stamens and monosulcate pollen appear to indicate that Archaefructus, as primitive angiosperms,might be derived from extinct seed -ferns during the Older Mesozoic. Archaefructus is considered Late Jurassic in age.  相似文献   

辽宁田师傅早中侏罗世植物群     

郑少林  张武 《国土资源》1990,(3)

田师傅植物群系我国北方典型的早中侏罗世植物群之一,产自辽宁本溪田师傅盆地及风城赛马-(?)阳盆地的下侏罗统长梁子组、中侏罗统大堡组及三个岭组。该植物群由34属77种植物组成。本文通过含植物化石地层剖面简介阐明化石的产地和层位,对以往的化石名单进行修订,对部分重要化石作了描述。  相似文献   

青海天峻南山蛇绿岩的地质特征及其形成环境     

王毅智  拜永山  陆海莲 《青海国土经略》2001,(1)

青海天峻南山蛇绿岩为本次1:5万区调中首次发现。从其地质特征、岩石化学及地球化学特征反映出陆内裂谷扩张的早石炭世小洋盆构造环境。它的发现对于重新认识宗务隆造山带的地质属性、地球动力学机制,与祁连造山带、柴达木地块的构造关系以及研究古特提斯洋演化提供了新的依据。  相似文献   

辽东早元古宙北辽河群里尔峪组层状硫铁矿     

邴贵先  金祥书  张述发 《国土资源》1990,(1)

辽阳隆昌—本溪草河口一带的硫铁矿及其它硫化物矿床(点),赋存于早元古宙北辽河群里尔峪组钠质火山岩段向碳酸盐岩过渡的层状岩系中,严格受里尔峪组控制。里尔峪组厚度为400—600m,由3个岩段组成,原岩为火山—沉积岩,火山岩属钙碱性火山喷发系列。矿床既受层位控制,亦受岩性控制。成矿物质通常来源于辽东早元古宙裂陷槽(构造活动带)内的钠质火山喷发,具工业价值的矿床受一定的岩相古地理条件及后期褶皱构造所控制。  相似文献   

Early and Middle Pleistocene vegetation history of the Médoc region,southwest France     

C. E. O'Brien  R. L. Jones 《第四纪科学杂志》2003,18(6):557-579

Pleistocene deposits, together with their pollen, plant macrofossil, foraminiferal, dinoflagellate and coleopteran remains, from five sites along the Atlantic coast of the Médoc Peninsula are described and discussed. Sediments making up the Négade Formation are shown to have been laid down under either estuarine or lagoonal conditions when closed Quercus–Pinus‐Tsuga canadensis regional woodland existed. Comparison with plant records from The Netherlands indicates that these deposits are most likely attributable to either the Early Pleistocene Bavel Interglacial (marine oxygen isotope stage (MIS) 31), or an interglacial of the Waalian (MIS 37–49) or Tiglian (MIS 63–79). In addition, clays assigned to the Argiles du Gurp sensu stricto, were similarly deposited in either an estuary or lagoon, which subsequently was cut off from the sea. A freshwater lake with vegetation dominated by Azolla filiculoides then developed. This was succeeded by reedswamp and an organic mud (termed Lignite in the corresponding French stratigraphical records) formed. Regional Quercus–Abies woodland was replaced by one with Pinus dominant and Pterocarya a minor component. Comparison with plant records from France and other parts of Europe suggest that the clays and organic mud might be correlated with the Holsteinian (Praclaux) Interglacial (MIS 11c). Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

企业财务预警分析模型及其运用     

周昌仕  李森木 《广东海洋大学学报》2003,23(2):94-99

为规避财务危机 ,减少财务损失 ,企业应经常性地利用财务会计报告和其他相关经营资料 ,结合运用多变量分析模型和单变量分析模型 ,进行财务预警动态分析 ,充分发挥其监测、诊断、预控和矫正的功能 ,从而保证企业持续、健康、有效地经营。  相似文献   

The First Discovery of the Earliest Devonian Conodont Zonal Fossil from the "Gavuu Member" in Mushgai Area of South Gobi,Mongolia     

Chengyuan Wang  W.Ziegler  Ch.Minjin  G.Sersmaa  J.Munchtsetseg  L.Gereltsetseg  I.Nadya 《世界地质(英文版)》2003,6(1)

Conodont Caudicriodus woschimidti woschmidti has been found from a big outcrop (hill) of the Bayan-Kho-shuu Ruins Section which was previously assigned to the Silurian Gavuu Member of the Mandalovoo Formation. This isfirst time to find the lowermost Devonian conodont zonal fossil in Mongolia. The lower part of the Gavuu Member is Silurian. But the strata from where we collected samples M-9～M-12 definitely belong to Lower Devonian (lower Lochko-vian) rather than Lower Silurian. The Mandalovoo Formation should be named Mandalovoo Group, and its three members should be changed into three formations.  相似文献   

东天山板块构造与金属矿产成矿规律     

Yang Xingke  Ji Jinsheng  Luo Guichang  Tao Hongxiang 《地球科学与环境学报》1997,(3)

根据东天山及邻区地层、沉积建造、构造岩石组合、变形、变质、古生物分区、深部地壳结构、地球物理、地球化学特征，以康古尔塔格－黄山深断裂为界，划分了不同级别的构造单元和构造沉积相带。统计分析了２０２个金属矿床，重点研究了金、银、铜、镍、钼、铁等矿产空间分布与板块构造、碰撞带关系，划分出九个成矿带，三个成矿期，以海西中晚期最为显著。成矿与板缘构造活动带地质演化密切相关，与俯冲一碰撞带和韧性剪切带时空演化最为密切。构造分区控制的矿产成带性和构造演化形成的成矿集中期之间相互转化对该区金属矿产有重要控制作用。  相似文献