腾冲新生代火山作用构造—岩浆类型的探讨——一种滞后型的弧火山   总被引：5，自引：2，他引：3  

赵崇贺  陈廷方 《现代地质》1992,6(2):119

腾冲火山群是我国著名的新生代火山群之一。它共分4个喷发期,根据K—Ar同位素地质年龄测定,第一期为2.93Ma,第二期为0.81Ma,第三期为0.31Ma,第四期为0.13Ma。该火山群为典型的钙碱性系列玄武岩—安山岩—英安岩弧火山岩组合。它喷发于晚上新世—晚更新世,但这一时期腾冲地区已为大陆板内环境,它可能与K₂末怒江洋壳俯冲作用有关。因此,腾冲弧火山岩的形成至少在俯冲作用停止以后60Ma,属于一种新的火山作用类型——碰撞后弧火山或滞后型弧火山。  相似文献   

北祁连山石灰沟奥陶纪岛弧火山岩系岩浆性质的确定   总被引：16，自引：0，他引：16       下载免费PDF全文

夏林圻  夏祖春  彭礼贵  任有祥  杨静华  张诚  李智佩  王兴安 《岩石矿物学杂志》1991,10(1):1-10

北祁连山石灰沟地区发育一套完整的奥陶纪岛弧火山岩系。中奥陶世始岛弧形成,初期为拉斑玄武质岩浆喷发,尔后以钙碱性火山活动为主,至中奥陶世末岛弧演化成熟,产生橄榄玄武质火山作用。  相似文献   

西秦岭地区钙碱质火山岩中石榴石的发现及其地质意义   总被引：1，自引：0，他引：1  

王松产  丁毅 《岩石矿物学杂志》1990,9(1):13-21

在西秦岭钙碱质火山岩中首次发现富铁铝成分的石榴石，成分与国外已有资料相比明显地富Ca。在证据表明，区内火山岩中石榴石不是外来捕获晶或残留相，而是偏“干”的岩浆处于早期高压环境下的结晶相。石榴石晶体周边生长的斜长石晶环并不是岩浆反应产物，而是岩浆在温压突变条件下以被消融残留的石榴石为中心从岩浆中直接晶出的。依据地质和实验岩石学资料推断，西秦岭中生代含石榴石钙碱质火山岩浆可能起源于50km以下的地壳基底。  相似文献   

宁远─道县辉长岩包体的地球化学特征     

郭峰  范蔚茗 《湖南地质》1996,(2)

宁远─道县地区中生代玄武岩中辉长岩包体的岩石化学─地球化学特征表明，辉长岩包体为钙碱性玄武岩系列，形成于活动大陆边缘火山孤环境。辉长岩的形成、侵位，与菲律宾板块自中生代以来向中国大陆俯冲作用有关。  相似文献   

白云鄂博辉长岩          下载免费PDF全文

胡辅佑  王凯怡  孟庆昌 《地质科学》1988,(3):259-271

白云鄂博辉长岩类包括淡辉长岩—辉长岩—碱性辉长岩。它们是由岩浆结晶分异过程形成的一套系列。在岩浆演化晚期阶段有碱金属和大离子亲石元素及轻稀土的一定程度的富集。  相似文献   

Première datation UPb des orthogneiss œillés de la zone axiale de la Montagne noire (Sud du Massif central) : nouveaux témoins du magmatisme ordovicien dans la chaı̂ne Varisque     

Françoise Roger  Jean-Patrick Respaut  Maurice Brunel  Philippe Matte  Jean-Louis Paquette 《Comptes Rendus Geoscience》2004,336(1):19-28

We present new U–Pb results on felsic Augen orthogneisses from the Axial Zone of the Montagne Noire (French Massif Central). The data indicate Ordovician ages, 456±3 and 450±6 Ma for two samples collected at ‘Pont-de-Larn’ and ‘Gorges d'Héric’, respectively. These ages are interpreted as the igneous emplacement age of the granitic protolith. To cite this article: F. Roger et al., C. R. Geoscience 336 (2004).  相似文献   

Cenozoic Adakite-type Volcanic Rocks in Qiangtang, Tibet and Its Significance   总被引：6，自引：0，他引：6  

LIU Shen  HU Ruizhong  FENG Caixi  CHI Xiaoguo  LI Cai  YANG Rihong  WANG Tianwu  JIN WeiGuiyang Institute of Geochemistry  Chinese Academy of Sciences  Guiyang  Guizhou E-mail: lliushen@hotmail.comGraduate School of the Chinese Academy of Sciences  Beijing College of Earth Sciences  Jilin University  Changchun  Jilin Aero Geophysical & Remote Sensing Center  Beijing 《《地质学报》英文版》2003,77(2):187-193

Volcanic rocks in the study area, including dacite, trachyandesite and mugearite, belong to the intermediate-acid, high-K calc-alkaline series, and possess the characteristics of adakite. The geochemistry of the rocks shows that the rocks are characterized by SiO2>59%, enrichment in A12O3(15.09-15.64%) and Na2O (>3.6%), high Sr (649-885 μg/g) and Sc, low Y contents (<17 μg/g), depletion in HREE (Yb<1.22 μg/g), (La/Yb)N>25, Sr/Y>40, MgO<3% (Mg<0.35), weak Eu anomaly (Eu/Eu=0.84-0.94), and lack of the high field strength elements (HFSE) (Nb, Ta, Ti, etc.). The Nd and Sr isotope data (87Sr/86Sr=0.7062-0.7079, 143Nd/144Nd=0.51166-0.51253, εNd= -18.61-0.02), show that the magma resulted from partial melting (10%-40%) of newly underplated basaltic lower crust under high pressure (1-4 GPa), and the petrogenesis is obviously affected by the crust's assimilation and fractional crystallization (AFC). This research will give an insight into the uplift mechanism of the Tibetan plateau.  相似文献   

Temporal Geochemical Evolution of Neogene Magmatism in the Baguio Gold–Copper Mining District (Northern Luzon, Philippines)     

Mireille Polve    Rene C. Maury    Sebastien Jego    Herve Bellon    Ahmed Margoum    Graciano P. Yumul  Jr  Betchaida D. Payot    Rodolfo A. Tamayo  Jr Joseph Cotten 《Resource Geology》2007,57(2):197-218

Baguio, in the Central Cordillera of Northern Luzon, is a district that displays porphyry copper and epithermal gold mineralization, associated with Early Miocene–Pliocene–Quaternary calc‐alkaline and adakitic intrusions. Systematic sampling, K‐Ar dating, major and trace elements, and Sr, Nd, Pb isotopic analyses of fresh magmatic rocks indicate three magmatic pulses: an Early Miocene phase (21.2–18.7 Ma), a Middle–Late Miocene phase (15.3–8 Ma) and finally a Pliocene–Quaternary event (3–1 Ma). The first phase emplaced evolved calc‐alkaline magmas, essentially within the Agno Batholith complex, and is thought to be related to the westward‐dipping subduction of the West Philippine Basin. After a quiescence period during which the Kennon limestone was deposited, magmatic activity resumed at 15.3 Ma, in connection with the start of the subduction of the South China Sea along the Manila Trench. It emplaced first petrogenetically related and relatively unradiogenic low‐K calc‐alkaline lavas and intermediate adakites. Temporal geochemical patterns observed from 15.3 to 1 Ma include progressive enrichment in K and other large ion lithophile elements, increase in radiogenic Sr and Pb and corresponding decrease in radiogenic Nd. These features are thought to reflect the progressive addition to the Luzon arc mantle wedge of incompatible elements largely inherited from South China Sea sediments. The origin of the long quiescence period, from 8 to 3 Ma, remains problematic. It might represent a local consequence of the docking of the Zambales ophiolitic terrane to Northern Luzon. Then, magmatic activity resumed at 3 Ma, emplacing chemically diversified rocks ranging from low K to high K and including a large proportion of adakites, especially during the Quaternary (dacitic plugs). The authors tentatively relate this diversity to the development of a slab tear linked with the subduction of the fossil South China Sea ridge beneath the Baguio area.  相似文献   

藏北赤布张错地区埃达克岩的厘定及其意义   总被引：7，自引：0，他引：7       下载免费PDF全文

魏君奇姚华舟  牛志军王建雄 《岩石矿物学杂志》2005,24(3):173-178

常量、微量及Sr、Nd同位素研究表明,藏北赤布张错地区分布的一套始新世(35～4 0Ma)高钾钙碱性火山岩具有C型埃达克岩的地球化学特征。火山岩SiO2 含量为5 8%～6 9% ,K2 O、Al2 O3 、Sr的含量相对偏高,而Y、Yb的含量和Mg# 值相对较低,Nb明显亏损,Zr、Ti、P弱亏损,LREE富集,无明显Eu负异常,ISr(0 .70 72 3～0 .70 777)值偏高,而INd(0 .5 12 32 0～0 .5 12 35 2 )值偏低,指示其为一套壳源中酸性火山岩系,源自加厚陆壳下部的一个榴辉岩质源区的部分熔融。这套新生代埃达克质火山岩的厘定,指示藏北羌塘地区或更大范围的大陆地壳在4 0Ma左右已经加厚到超过4 0km ,且青藏高原的隆升开始于4 0Ma以前。  相似文献   

The 2.73 Ga I-type granites in the Lengshui Complex and implications for the Neoarchean tectonic evolution of the Yangtze Craton     

Mingda Huang  Guangming Ren  Jinwei Guo  Fei Ren  Weihua Pang 《International Geology Review》2020,62(6):649-664

ABSTRACT

We report the oldest I-type granites in the Lengshui Complex of the Yangtze Craton, providing new insights for its tectonic evolution during the Neoarchean. An approach-combined study of zircon U-Pb dating and Lu-Hf isotopes, as well as whole-rock element geochemistry and Nd isotopes, were employed. LA-ICP-MS zircon U-Pb dating for the monzogranite sample LSG03 and LSG16 yielded ages of 2732 ± 13 Ma and 2738 ± 25 Ma, respectively. The more precise age of 2732 ± 13 Ma for the sample LSG03 was taken as the crystallization age of the monzogranite. These rocks have high SiO₂ (73.11–74.01 wt%), K₂O (3.93–5.48 wt%), Na₂O (3.93–4.86 wt%) and low CaO (0.30–0.69 wt%), MgO (0.17–0.30 wt%), TiO₂ (0.14–0.17 wt%), P₂O₅ (0.01–0.06 wt%), Al₂O₃ (14.11–14.37 wt%) content with weakly peraluminous affinity (A/CNK = 1.04–1.11). Geochemically, they belong to I-type granites, indicating partial melting of a thickened lower crust. Their relatively high Nb/Ta (15.2–34.8) ratios further suggest they formed under eclogite-facies conditions. The consistent whole-rock Nd and zircon Hf isotopic compositions indicate a homogeneous source. According to their ε_Hf(t) values (?2.0 to 0.8), two-stage Hf model ages (3.1 to 3.2 Ga) and positive ε_Nd(t) (1.4 to 2.1), we argue that they were probably generated by partial melting of a juvenile lower crust with little ancient materials. Monzogranites formed in a late-orogenic or collisional compressive tectonic regime, whereas subsequent ca. 2.73 Ga and 2.67–2.62 Ga A-type granites in the Zhongxiang Uplift (including the Lengshui Complex) may represent a prolonged extensional setting. Thus, Archean subduction (probably unlike modern subduction) likely occurred prior to ca. 2.73 Ga. Similar magmatism in the Kongling Complex implies that the Zhongxiang Uplift may have accrete to the Kongling Complex during the early Neoarchean. The transition from I-type to A-type magmatism may have resulted from a change in the geodynamic regime from the late-orogenic or collisional compressive environment to an extensional environment caused by the subsequent lithospheric collapse and mantle upwelling, suggesting an early Neoarchean orogenic event in the eastern Yangtze Craton.  相似文献