首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   366篇
  免费   76篇
  国内免费   152篇
地球物理   24篇
地质学   535篇
海洋学   6篇
综合类   8篇
自然地理   21篇
  2023年   6篇
  2022年   12篇
  2021年   19篇
  2020年   14篇
  2019年   12篇
  2018年   10篇
  2017年   22篇
  2016年   18篇
  2015年   14篇
  2014年   24篇
  2013年   32篇
  2012年   28篇
  2011年   14篇
  2010年   16篇
  2009年   23篇
  2008年   23篇
  2007年   22篇
  2006年   35篇
  2005年   16篇
  2004年   27篇
  2003年   17篇
  2002年   22篇
  2001年   17篇
  2000年   18篇
  1999年   22篇
  1998年   19篇
  1997年   15篇
  1996年   17篇
  1995年   17篇
  1994年   9篇
  1993年   7篇
  1992年   8篇
  1991年   5篇
  1990年   2篇
  1989年   4篇
  1988年   4篇
  1987年   3篇
  1985年   1篇
排序方式: 共有594条查询结果,搜索用时 15 毫秒
1.
The Jiajiwaxi pluton in the southern portion of the West Kunlun Range can be divided into two collision–related intrusive rock series, i.e., a gabbro–quartz diorite–granodiorite series that formed at 224±2.0 Ma and a monzonitic granite–syenogranite series that formed at 222±2.0 Ma. The systematic analysis of zircon U-Pb geochronology and bulk geochemistry is used to discuss the magmatic origin(material source and thermal source), tectonic setting, genesis and geotectonic implications of these rocks. The results of this analysis indicate that the parent magma of the first series, representing a transition from I-type to S-type granites, formed from thermally triggered partial melting of deep crustal components in an early island–arc–type igneous complex, similar to an I-type granite, during the continental collision orogenic stage. The parent magma of the second series, corresponding to an S-type granite, formed from the partial melting of forearc accretionary wedge sediments in a subduction zone in the late Palaeozoic–Triassic. During continued collision, the second series magma was emplaced into the first series pluton along a central fault zone in the original island arc region, forming an immiscible puncture-type complex. The deep tectonothermal events associated with the continent–continent collision during the orogenic cycle are constrained by the compositions and origins of the two series. The new information provided by this paper will aid in future research into the dynamic mechanisms affecting magmatic evolution in the West Kunlun orogenic belt.  相似文献   
2.
《地学前缘(英文版)》2020,11(3):925-942
The Pb isotope composition of the upper mantle beneath Central Europe is heterogeneous due to the subduction of regionally contrasting material during the Variscan and Alpine orogenies.Late Variscan to Cenozoic mantlederived melts allow mapping this heterogeneity on a regional scale for the last ca.340 Myr.Late Cretaceous and Cenozoic anorogenic magmatic rocks of the Bohemian Massif(lamprophyres,volcanic rocks of basanite/tephrite and trachyte/phonolite series) concentrate mostly in the Eger Rift.Cretaceous ultramafic lamprophyres yielded the most radiogenic Pb isotope signatures reflecting a maximum contribution from metasomatised lithospheric mantle,whereas Tertiary alkaline lamprophyres originated from mantle with less radiogenic ~(206)Pb/~(204)b ratios suggesting a more substantial modification of lithospheric source by interaction with asthenosphericderived melts.Cenozoic volcanic rocks of the basanite/tephrite and trachyte/phonolite series define a linear mixing trend between these components,indicating dilution of the initial lithospheric mantle signature by upwelling asthenosphere during rifting.The Pb isotope composition of Late Cretaceous and Cenozoic magmatic rocks of the Bohemian Massif follows the same Pb growth curve as Variscan orogenic lamprophyres and lamproites that formed during the collision between Laurussia,Gondwana,and associated terranes.This implies that the crustal Pb signature in the post-Variscan mantle is repeatedly sampled by younger anorogenic melts.Most Cenozoic mantle-derived rocks of Central Europe show similar Pb isotope ranges as the Bohemian Massif.  相似文献   
3.
李晓波  张艳  仝亚博 《地学前缘》2021,28(2):391-411
自中、晚侏罗世之交至早白垩世早期,中国东部发生了构造格局和古地理环境的巨大转变。对这一时期燕辽东段古地理和古环境的部分问题进行了多学科整合分析,初步认识如下:中侏罗世开始增强的板块汇聚造成中、晚侏罗世亚洲东部地壳增厚和地势升高,古太平洋伊泽纳崎板块持续俯冲引起深部岩浆上涌、地壳减薄和多期伸展裂陷,同时东亚洋陆过渡带形成一系列逃逸构造,上述构造演化导致燕辽地区在晚侏罗世至早白垩世中期形成高山和盆岭地貌。早白垩世137~131 Ma,嫩江—八里罕断裂至喀喇沁变质核杂岩延伸线两侧出现东高西低的地貌差异,相对下降的冀北—大兴安岭火山-地堑带地层中赋存热河生物群早期化石组合,而辽西—松辽地区为相对隆升的构造高地。130~110 Ma时期裂陷作用扩展,热河生物群中、晚期组合向周围扩散。热河生物群生存时期总体为以干冷为主的温带大陆性气候,这与中生代中国东部高原的潜在环境效应并不矛盾。全球气候演化和区域构造古地理条件共同导致燕辽地区自晚侏罗世至早白垩世的干旱化和寒冷化,并影响到中、晚侏罗世燕辽生物群和早白垩世热河生物群之间的生态群进化演替。  相似文献   
4.
豫西地区中上三叠统主要出露在济源、义马、伊川和南召一带。印支期秦岭造山运动控制和影响着邻区中上三叠统盆地属性和沉积地层展布。通过观察研究区野外露头剖面,发现中上三叠统发育一系列典型的软沉积变形构造,包括液化底辟、枕状构造、液化柱、液化卷曲变形、负载、球-枕、火焰状构造、液化角砾岩。这些软沉积变形在垂向上表现出明显的复现性,在侧向上表现为沿地层连续展布,表明该时期研究区内地层受到频繁强烈的地震影响。通过对这些软沉积现象的识别和形成机制解释,判定其触发因素为秦岭造山过程中伴生的地震。区内地层中震积岩的存在即是对秦岭造山过程中构造活动的响应。  相似文献   
5.
《地学前缘(英文版)》2020,11(4):1133-1144
The Shatsky and Hess Rises,the Mid-Pacific Mountains and the Line Islands large igneous provinces(LIPs) present different challenges to conventional plume models.Resolving the genesis of these LIPs is important not only for a more complete understanding of mantle plumes and plume-generated magmatism,but also for establishing the role of subducted LIP conjugates in the evolution of the Laramide orogeny and other circum-Pacific orogenic events,which are related to the development of large porphyry systems.Given past difficulties in developing consistent geodynamic models for these LIPs,it is useful to consider whether viable alternative geodynamic scenarios may be provided by recent concepts such as melt channel networks and channel-associated lineaments,along with the "two mode"model of melt generation,where a deeply-sourced channel network is superimposed on the plume,evolving and adapting over millions of years.A plume may also interact with transform faults in close proximity to a mid ocean ridge,with the resultant bathymetric character strongly affected by the relative age difference of lithosphere across the fault.Our results suggest that the new two-mode melt models resolve key persistent issues associated with the Shatsky Rise and other LIPs and provide evidence for the existence of a conduit system within plumes that feed deeply-sourced material to the plume head,with flow maintained over considerable distances.The conduit system eventually breaks down during plume-ridge separation and may do so prior to the plume head being freed from the triple junction or spreading ridge.There is evidence for not only plume head capture by a triple junction but also for substantial deformation of the plume stem as the distance between the stem and anchored plume head increases.The evidence suggests that young transforms can serve as pathways for plume material migration,at least in certain plume head-transform configurations.A fortuitous similarity between the path of the Shatsky and Sio plumes,with respect to young spreading ridges and transforms,helps to clarify previously problematic bathymetric features that were not readily ascribed to fixed plumes alone.The Line Island Chain,which has been the subject of a vast number of models,is related mainly to several plumes that passed beneath the same region of oceanic crust,a relatively rare event that has resulted in LIP formation rather than a regular seamount track.Our findings have important implications for the timing and mechanism for the Laramide Orogeny in North America,demonstrating that the Hess Rise conjugate may be much smaller than traditionally thought.The Mid Pacific Mountains conjugate may not exist at all,given large parts of these LIPs were formed at an ‘off-ridge' site.This needs to be taken into account while considering the effects of conjugate collision on mineralization and orogenic events.  相似文献   
6.
《地学前缘(英文版)》2020,11(6):2243-2269
The Gurupi Belt, in north-northeastern Brazil, is a mobile belt developed in the south-southwestern margin of the São Luís cratonic fragment and crops out as a tectonic and erosional window within the Phanerozoic cover. Field, petrographic, geochemical, geochronological, and Nd isotopic information (new and published) constrain the timing and types of magmatic associations present in the belt and the tectonic settings in which they formed. The Rhyacian was the main period of magmatic activity, which can be grouped into two main stages. (1) ~2185–2130 ​Ma: pre-collisional, juvenile, calc-alkaline magnesian and calcic ferroan granitoid suites, and minor calc-alkaline and tholeiitic mafic plutonism (now amphibolites), formed in intra-oceanic to transitional/continental arcs; and intra- or back-arc volcano-sedimentary basin. (2) ~2125–2070 ​Ma: syn- (two-mica granites) to late-collisional (potassic to shoshonitic granites and quartz-syenite) plutonic suites produced after crustal thickening and melting, with localized migmatization, that intruded during the compressive D1 deformational phase and concomitantly with greenschist to amphibolite metamorphism. There is a zonation of the Rhyacian episodes, with intra-oceanic stages occurring to the northeast, and the continental arc and collisional phases occurring to the southwest, indicating the presence of an active continental margin to the southwest, and subduction from NE to SW (present-day configuration). This magmatic framework is a continuation to the south of what is described for the São Luís cratonic fragment to the north, and the orogenic scenario is identical to what is observed for the same period in the West African Craton (Eburnean/Birrimian orogen), which additionally supports previous geological correlations. In the Neoproterozoic, a few magmatic occurrences are recognized. An extensional event allowed the intrusion of an anorogenic, nepheline syenite at ca. 730 Ma, which was followed by the intrusion of a crustal, calc-alkaline microtonalite, of uncertain tectonic setting, at 624 ​Ma. Both intrusions underwent greenschist to amphibolite facies metamorphism between 580 Ma and 529 ​Ma. This metamorphic event is probably related to crustal thickening, which produced crustal melting and intrusion of two-mica granites between 595 Ma and 549 ​Ma. The absence of oceanic and arc-related assemblages, along with geophysical information about the basement of the Phanerozoic cover indicates an intracontinental setting for the Neoproterozoic–Early Cambrian evolution of the Gurupi Belt, with rifting and posterior closure of the basin, without oceanization. Rifting and closure correlate in time with the onset of Rodinia breakup and West Gondwana assembly, respectively, but we interpret the events in the Gurupi Belt as having no direct role in these two global supercontinent-related events, but, instead, as being related to orogenic events occurring in the periphery of the West African and Amazonian cratons at that time.  相似文献   
7.
关于秦岭造山带   总被引:4,自引:4,他引:0  
纪念老一代地球科学家李四光先生,思考地球科学与大地构造学的创新发展。文章以秦岭造山带为例思考大陆复合造山及其动力学,认知概括秦岭造山带基本属性与特质,探索认识中小多板块多期洋陆俯冲造山-陆-陆板块俯冲碰撞造山的板块复合造山,并又强烈叠加复合陆内造山,造成复杂组成与结构,形成立交桥式四维流变学分层的多层非耦合动态演化的大陆复合造山带模型,及其新的演化趋势动态和构成国家人类需求的成矿成藏物质财富与宜居的地表系统环境等,期望前瞻探索认知地球发展的未来。文章还就秦岭造山带几个有争议的问题,进行简要讨论,共求新的探索研究发展。期盼学习李四光先生学术理论精华,尤其在深化发展板块构造,探索认知大陆构造与动力学方面,创新发展地质力学,以宇宙太阳系视野探索地球动力学,推动大地构造新发展。   相似文献   
8.
In the late Silurian, the Lachlan Orogen of southeastern Australia had a varied paleogeography with deep-marine, shallow-marine, subaerial environments and widespread igneous activity reflecting an extensional backarc setting. This changed to a compressional–extensional regime in the Devonian associated with episodic compressional events, including the Bindian, Tabberabberan and Kanimblan orogenies. The Early Devonian Bindian Orogeny was associated with SSE transport of the Wagga–Omeo Zone that was synchronous with thick sedimentation in the Cobar and Darling basins in central and western New South Wales. Shortening has been controlled by the margins of the Wagga–Omeo Zone with partitioning along strike-slip faults, such as along the Gilmore Fault, and inversion of pre-existing extensional basins including the Limestone Creek Graben and the Canbelego–Mineral Hill Volcanic Belt. Shortening was more widespread in the late Early Devonian to Middle Devonian Tabberabberan Orogeny, with major deformation in the Melbourne Zone, Cobar Basin and eastern Lachlan Orogen. In the eastern Melbourne Zone, structural trends have been controlled by the pre-existing structural grain in the adjacent Tabberabbera Zone. Elsewhere Tabberabberan deformation involved inversion of pre-existing rifts resulting in a variation in structural trends. In the Early Carboniferous, the Lachlan Orogen was in a compressional backarc setting west of the New England continental margin arc with Kanimblan deformation most evident in Upper Devonian units in the eastern Lachlan Orogen. Kanimblan structures include major thrusts and associated fault-propagation folds indicated by footwall synclines with a steeply dipping to overturned limb adjacent to the fault. Ongoing deformation and sedimentation have been documented in the Mt Howitt Province of eastern Victoria. Overall, structural trends reflect a combination of controls provided by reactivation of pre-existing contractional and extensional structures in dominantly E–W shortening operating intermittently from the earliest Devonian to Early Carboniferous.  相似文献   
9.
许欢  柳永清  旷红伟  彭楠  江小均 《地质通报》2017,36(11):1893-1918
燕山运动是中国东部晚中生代重要的陆内造山运动,具有广泛而深远的地质影响。虽然前人对燕山运动的研究已近百年,积累了大量研究成果,然而目前对于燕山造山带的陆内造山过程仍存在很大争议。针对这一科学问题,选取燕山西部尚义盆地开展了1∶5万专题地质填图。在此基础上,通过盆地充填序列、岩相、沉积环境、物源的综合分析,恢复了盆地岩相古地理,建立了盆地演化模型,并探讨了燕山造山带陆内造山过程的沉积响应。根据沉积岩区岩相组合填图方法,绘制了1∶5万组-相级岩相分布图。燕山西部尚义盆地侏罗纪—早白垩世早期沉积演化记录了燕山造山带造山前伸展、同造山挤压和造山后伸展的全过程。  相似文献   
10.
笔者对中天山微陆块北缘托克逊干沟地区角闪岩相变质岩中的锆石进行了U-Pb年代学研究,结果证明变质沉积岩中的碎屑锆石记录了从太古宙至元古宙(3320~530 Ma)的源区岩浆热事件,变质火成岩中的岩浆锆石记录了新元古代晚期(550 Ma)的岩浆作用,而变质锆石记录了晚泥盆纪(385~360 Ma)的变质作用。这一定年结果表明,中天山微陆块北缘的造山作用很可能发生在华力西期,中天山微陆块形成于新元古代以前,但并没有经历前寒武纪变质作用,具有与塔里木克拉通明显不同的前寒武纪构造演化历史。因此,中天山微陆块很可能是一个独立的块体,并不支持其是从塔里木板块分离出来的观点。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号