南海大洋钻探及海洋地质与地球物理前沿研究新突破   总被引：2，自引：2，他引：0  

林间  李家彪  徐义刚  孙珍  夏少红  黄小龙  解习农  李春峰  丁巍伟  周志远  张帆  罗怡鸣 《海洋学报》2019,41(10):125-140

南海是西太平洋地区规模最大且具有代表性的边缘海盆地之一。经过近几十年的研究积累,尤其是通过实施5个国际大洋钻探航次(1999–2018年)与国家自然科学基金委“南海深海过程演变”重大研究计划(2011–2019年),我国科学家获得了大量宝贵的第一手资料,取得了一系列创新进展与重大突破,标志着南海海洋地质与地球物理研究正走向国际前沿。重要研究成果包括:(1)新提出南海是“板缘张裂”盆地,与经典的大西洋型陆缘模式不同;(2)大洋钻探首次获取了基底玄武岩样品,结合中国在南海首次深拖地磁测量实验,精确测定了南海海盆玄武岩年龄,揭示南海海盆从东向西分段扩张;(3)大洋钻探结果发现南海陆缘岩石圈减薄之初岩浆迅速出现,未发现缓慢破裂造成的蛇纹岩出露;(4)发现南海扩张结束后仍存在大量岩浆活动,可能受控于多种构造与地幔因素;(5)地球化学证据与地球动力学模拟都显示南海岩浆的形成受到周边俯冲带的影响。目前我国的海洋地球科学正在进入崭新的发展阶段,有望以南海为基点,开始拓展到周边大洋,通过主导大型研究计划以及建设我国大洋钻探平台,以提升我国在南海、西太平洋与印度洋海洋地质科学研究的实质性影响力与引领地位。  相似文献   

Geochemical features of felsic magmatism on the northwestern flank of the Khingan-Okhotsk volcanoplutonic belt: Ezop and Yam-Alin zones     

I. M. Derbeko  A. A. Sorokin  S. G. Agafonenko 《Russian Journal of Pacific Geology》2008,2(1):54-63

The Ezop-Yam-Alin zone was studied with emphasis on the geology, composition, and age of its felsic volcanic and intrusive rocks. All these rocks are moderately enriched in Rb (84–268 ppm), Ba (240–881 ppm), Th (10.5–17.9 ppm), and REE and depleted in Nb (5–12 ppm), Ta (0.5–1.2 ppm), and Zr (92–175 ppm). The age dates obtained by U-Pb (94.8 ± 2.2 Ma) and Rb-Sr (95.2 ± 0.69 Ma) methods for the granites of the Ezop Complex correspond to the Cenomanian.  相似文献   

Composition and genesis of the intrusive rock association of the Magloi magmatic area,the Central Amur region     

V. G. Gonevchuk  G. A. Gonevchuk 《Russian Journal of Pacific Geology》2008,2(1):39-53

New geochemical and isotopic-geochronological data are reported on the intrusive association from one of the largest and relatively poorly studied Cretaceous (Aptian-Cenomanian) magmatic zones of the Sikhote-Alin accretionary fold system. The new results and previously published studies were interpreted using concepts of a blocked (terrane) structure of the region and the different geodynamic nature of the magmatic complexes. It was shown that the “transitional” geochemical and geodynamic characteristics of the studied intrusive rocks can be explained in terms of magmatism along the transform continental margin. Additional complicating factors are the composition of the terrane rocks and the change in the geodynamic setting during the formation of the considered magmatic area (114-90 Ma).  相似文献   

塔西南玄武岩年代学和地球化学特征及其对二叠纪地幔柱岩浆演化的制约   总被引：20，自引：13，他引：7  

厉子龙  杨树锋  陈汉林  余星  林秀彬  励音骐 《岩石学报》2008,24(5)

本文通过对塔西南达木斯剖面中玄武岩进行K-Ar同位素定年,获得年龄为289.6Ma,并结合Ar-Ar坪年龄结果(290.1Ma)和古生物以及沉积特征,认为290Ma的年龄代表了塔西南玄武岩形成于早二叠世,对应于盆地内下二叠统库普库兹满组下段层位的年龄.地球化学特征显示塔西南熔岩为分异的碱性玄武岩并含45%SiO2和4%MgO含量.塔西南玄武岩与盆地内柯坪玄武岩具有相近的主量元素含量和稀土配分与微量元素蜘蛛网图型、无Eu异常、富集轻稀土元素、较高的其它不相容元素(如高场强元素).但塔西南玄武岩比柯坪玄武岩具有较高的A12O2和CaO含量及稀土总量(288×10-6～358×10-6),偏低的Na2O,P2O5和FeO含量.K、Rb和Cs丰度的无系统性变化主要受这些元素丰度本身变化的影响.对其它不活动组分,塔西南玄武岩具有高Ti(Ti/Y=522～624)和Nb含量(30×10-6～40×10-6)及低zr/Nb比值,暗示其来自富集的地幔源区.其Nb含量相对La含量无显著变化以及相对低的Nb/U(近30)和Ce/Pb比值(近15),指示塔西南玄武熔岩来自大陆岩石圈或受一定程度的地壳混染.塔里木盆地大规模的火山喷发以及富集不相容元素的地球化学特征支持这样一种假设,即塔西南玄武岩来自地幔柱火山作用,或由于地幔柱的供热和上升导致富集的岩石圈地幔部分熔融而形成.且岩浆作用过程以部分熔融为主,结晶分异作用较弱.基于塔西南玄武岩和柯坪玄武岩相近的时代、源区成分和/或岩浆作用过程以及处于陆内稳定构造环境,笔者认为塔里木二叠纪玄武岩的分布范围可以从塔里木盆地内的塔中、柯坪一带一直延伸到塔西南地区.  相似文献   

Petrogenesis of Permian alkaline lamprophyres and diabases from the Spanish Central System and their geodynamic context within western Europe   总被引：1，自引：1，他引：0  

D. Orejana  C. Villaseca  K. Billström  B. A. Paterson 《Contributions to Mineralogy and Petrology》2008,156(4):477-500

Basic to ultrabasic alkaline lamprophyres and diabases intruded within the Spanish Central System (SCS) during Upper Permian. Their high LREE, LILE and HFSE contents, together with positive Nb–Ta anomalies, link their origin with the infiltration of sublithospheric K-rich fluids. These alkaline dykes may be classified in two distinct groups according to the Sr–Nd isotope ratios: (1) a depleted PREMA-like asthenospheric component, and (2) a BSE-like lithospheric component. A slight enrichment in radiogenic ²⁰⁷Pb and ²⁰⁸Pb allows the contribution of a recycled crustal or lithospheric component in the mantle sources. The intrusion of this alkaline magmatism is likely to have occurred due to adiabatic decompression and mantle upwelling in the context of the widespread rifting developed from Carboniferous to Permian in western Europe. The clear differences in the geochemical affinity of Lower Permian basic magmas from north-western and south-western Europe might be interpreted in terms of a more extensive separation of both regions during that period, until they were assembled during Upper Permian. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

Geochronology of Pliocene volcanism in the Dzhavakheti Highland (the Lesser Caucasus). Part 2: Eastern part of the Dzhavakheti Highland. Regional geological correlation     

V. A. Lebedev  S. N. Bubnov  O. Z. Dudauri  G. T. Vashakidze 《Stratigraphy and Geological Correlation》2008,16(5):553-574

The results of isotopic-geochronological study of the Pliocene volcanic rocks in reference sections and volcanic edifices of eastern part of the Dzhavakheti Highland (the northwestern Lesser Caucasus) are considered. The isotopic-geochronological data obtained here are correlated with data on western part of the Dzhavakheti Highland, which have been considered in previous part of this work. Based on correlation, time spans of principal volcanic events of the Pliocene in the study region as a whole are determined, and general trends of the young magmatism evolution within the region are established. In sum, the isotopic-geochronological dates evidence that the Pliocene magmatism of the Dzhavakheti Highland developed practically without essential breaks during the period of about 2 Ma long, from 3.75 to 1.75–1.55 Ma ago. The areal basic volcanism that was most widespread at that time is divisible into five discrete phases according to the isotopic dates obtained. Comparatively short pauses, which separated these phases of magmatic activity, were a few hundreds thousand years long, not more. Chemical composition of moderately acidic to silicic volcanics, which are of a limited distribution in the Dzhavakheti Highland, and their age relations with basic lavas of the region suggest that they are most likely the differentiation products of parental basic mantle-derived magmas. The analyzed distribution of volcanic centers, which erupted basic lavas of the Dzhavakheti Highland, evidence that first two phases of basic magmatism were connected here with volcanic activity in southwestern part of the region (northern termination of the Egnakhag Ridge), whereas activity of volcanoes situated on the east, predominantly in water-shed part and on slopes of the submeridional Dzhavakheti Ridge, controlled development of the third and fourth phases. Consequently, magmatic activity of the Pliocene stage in history of the Neogene-Quaternary magmatism of the Dzhavakheti Highland laterally migrated from the west to the east, being controlled by development of regional submeridional extension zones. Volcanic ridges marking the latter are formed by volcanic edifices, which are amalgamated at their bases and have erupted lavas of close age and composition. The migration of volcanic activity can be described in terms of the “domino effect,” when cessation of volcanism in one zone led to formation of the other submeridional zone of extension and magmatic activity displaced from the west eastward in sublatitudinal direction. In general, evolution of the Pliocene magmatism of the Dzhavakheti Highland, was similar, despite the essential regional peculiarities, to the generalized trend of magmatism evolution in the continental rifts and intraplate zones of the “hot-spot” type.  相似文献   

Geochemistry of the mafic dykes in the Prakasam Alkaline Province of Eastern Ghats Belt, India: Implications for the genesis of continental rift-zone magmatism     

K. Vijaya Kumar  K. Rathna 《Lithos》2008,104(1-4):306-326

Mesoproterozoic rift-zone magmatism in the Prakasam Alkaline Province of Eastern Ghats Belt, India is represented by three geochemically distinct primary mafic magmas and their plutonic differentiates. The three mafic magmas correspond to the alkali basaltic dykes, gabbroic dykes and lamprophyric dykes. The dyke activity is synchronous with the host plutons and belongs to the 1350–1250 Ma period Mesoproterozoic magmatism. Geochemical signatures suggest that the alkali basaltic dykes have a source in the thermal boundary layer, which has a history of prior melt extraction followed by enrichment. Both the gabbroic and lamprophyric dykes are derived from lithospheric sources and their geochemical variation can be explained by “vein-plus-wall-rock melting model”. Vein/wall-rock ratio is low for the sources of gabbroic dykes, whereas it is high for the lamprophyric dykes. Geochemistry of the gabbro dykes further indicates preservation of previous arc-signals by the lithosphere beneath the Prakasam Alkaline Province during the Mesoproterozoic. Geochemical signatures of lamproite, which could be a cratonic expression of the rift-triggered magmatism in the Prakasam Province, suggest a general increase in the metasomatic imprint with increasing lithosphere thickness from cratonic margin towards interior. It is found that geochemistry of continental rift-zone magmatism of the Prakasam rift is remarkably similar to that of the Gardar rift of South Greenland. It appears that the geodynamic conditions under which melting occurred in the Prakasam Alkaline Province are similar to that of a propagating rift with variable contributions from the convective mantle and subcontinental lithosphere mantle to the rift-zone magmas. The present study illustrates how fertility and chemical heterogeneity of the lithosphere play significant roles in the creation of enormous geochemical diversity characteristic of continental rift-zone magmatism.  相似文献   

The Source System of Mesozoic Magmatism in Middle and Lower Yangtze Valleys and Adjacent Areas—A Geochemical Tracer Study     

马振东  单光祥 《中国地球化学学报》1997,16(2):105-111

The mechanism that controls regional mineralization must be governed by a series of geochemical reactions in relation to the source system of magmatism.In this respect,the geological bodies must have been overprinted by various kinds of tracers in terms of either chemical elements or isotopes.For this reason,the problem may be better approached by treating the lithosphere as a whole with due considerations given to the various tracer elements and isotopes and the various media of the magmatism(magmatic as well as sedimentary rocks).Presented in this paper are the results of this attempt based on a great wealth of available data concerning the source system of Mesozoic magmatism in the Middle and Lower Yangtze Valleys and adjacent areas.  相似文献   

岩浆作用与地球动力学刍议——以中国东南沿海为例   总被引：4，自引：0，他引：4       下载免费PDF全文

王德滋  周全城 《岩石矿物学杂志》1991,(3)

岩浆活动是地球动力学事件的一个重要方面,本文从这点出发,讨论了中国东南沿海中、新代时期地球动力学环境的演变对岩浆活动的制约作用。  相似文献   

广东省龙川县天堂山锡多金属矿床成岩成矿时代及其地质意义     

贾宏翔  庞振山  耿林  张志辉  贾儒雅 《地质论评》2016,62(S1):107-108

天堂山锡多金属矿床位于广东省龙川县,是近年发现的一处以锡为主的中型多金属矿床。矿床大地构造位置位于南岭成矿带的东段,河源深断裂带与大东山—浰源—罗浮东西向深断裂带交汇处附近,中生代大长沙火山岩盆地中南部边缘。矿区出露地层为侏罗系上统高基坪群中亚群下段的中酸性火山岩。矿区内的火山角砾岩受北北东向断裂控制,隐爆角砾岩在矿区中东部地表有出露,钻孔中也有分布,厚度一般几米,角砾成分主要为火山岩,胶结物主要由硅质、绢云母和同成分火山岩碎屑组成,岩石具较强的绿泥石化,地表的隐爆角砾岩中无矿化;矿区火山熔岩—火山碎屑岩在剖面上具多次喷溢—喷出—间歇—喷溢（伴随局部隐爆）—喷出的火山韵律特征。矿区内断裂构造发育,受区域应力场控制,主要有北东—北北东向F1和F2断层、近南北—北北西向断裂带二组。矿区内侵入岩不发育,仅于中部偏西和南东部出露石英斑岩脉,钻探工程揭露表明矿床深部存在隐伏花岗岩体,其顶部为石英斑岩,并且石英斑岩多发生强烈的气液蚀变。  相似文献