浙江中生代火山岩时代厘定和问题讨论：兼评Lapierre等关于浙江中？…   总被引：12，自引：1，他引：11  

陶奎元  邢光福 《地质论评》2000,46(1):14-21

浙江中生代火山岩的时代长期以来存在不同意见,主要分岐为浙江磨石山群和浙西建德群时代窨是晚侏罗世、早白垩世、抑或晚白垩世。Ｌａｐｉｅｒｒｅ等（１９９７）的一文中据两条Ｒｂ－Ｓｒ等时线年龄,给出了如下论断;浙西火山活动（建德群）时代为１２４Ｍａ,划归为第一幕第一次岩浆事件;浙东（磨石山群）时代为９７Ｍａ,划归为第一幕第二次岩浆事件,而第二幕岩浆事件（指永康群）时代〈９７Ｍａ,本文就Ｌａｐｉｅｒｒｅ等文  相似文献   

Geology and Mineral Chemistry of the Deosai Volcanics, Baltistan, N. Pakistan     

Syed Hamidullah 《地学前缘》2000,(Z1)

GEOLOGY AND MINERAL CHEMISTRY OF THE DEOSAI VOLCANICS, BALTISTAN, N. PAKISTAN  相似文献   

The Cenozoic Volcanoes in Northeast China     

LIU Jiaqi  HAN Jingtai  GUO Zhengfu 《东北亚地学研究》2002,(2)

1　ＧｅｏｌｏｇｉｃａｌＢａｃｋｇｒｏｕｎｄＥｖｅｎｎｏｆａｓｃｉｎａｔｉｎｇｖｏｌｃａｎｉｃｅｒｕｐｔｉｏｎｏｃｃｕｒｒｅｄｉｎＣｈｉｎａｉｎｍｏｄｅｒｎｔｉｍｅｓ ,ｔｈｅｒｅａｒｅｍａｎｙＣｅｎｏｚｏｉｃｖｏｌｃａ ｎｏｅｓａｎｄｖｏｌｃａｎｉｃｒｏｃｋｓｄｉｓｔｒｉｂｕｔｅｄｉｎｔｈｅｅａｓｔｅｒｎｃｏｎｔｉ ｎｅｎｔｍａｒｇｉｎａｎｄｔｈｅｎｏｒｔｈｅｒｎＴｉｂｅｔａｎｐｌａｔｅａｕ .Ｅｓｐｅｃｉａｌｌｙｔｈｅｆｒｅｑｕｅｎｔｖｏｌｃａｎｉｃａｃｔｉｖｉｔｉｅｓｏｃｃｕｒｒｅｄｉｎｎｏｒｔ…  相似文献   

Petrogenetic Evolution of the Bayan Gol Ophiolite— Geological Record of an Early Carboniferous "Red Sea Type"Ocean Basin in the Tianshan Mountains, Northwestern China   总被引：3，自引：0，他引：3  

XIA Linqi  LI Xiangmin  XU Xueyi  XIA Zuchun  MA Zhongping  WANG Lishe Xi''an Institute of Geology  Mineral Resources  China Geological Survey  Xi''an  Shaanxi 《《地质学报》英文版》2005,79(2):174-192

The Bayan Gol ophiolite fragment is a portion of the North Tianshan Early Carboniferous ophiolite belt. This ophiolite belt represents a geological record of an Early Carboniferous “Red Sea type” ocean basin that was developed on the northern margin of the Tianshan Carboniferous-Permian rift system in northwestern China. The late Early Carboniferous Bayan Gol ophiolite suite was emplaced in an Early Carboniferous rift volcanosedimentary succession of shallow-marine to continental facies (Volcanics Unit). Ophiolitic rocks in the Bayan Gol area comprise ultramafic rocks, gabbros with associated plagiogranite veins, diorite, diabase, pillow basalts and massive lavas. The Early Carboniferous tiffing and the opening process of the North Tianshan ocean basin produced mafic magmas in composition of tholeiite and minor amounts of evolved magmas. Compositions of trace elements and Nd, Sr and Pb isotopes reveal the presence of two distinct mantle sources: (1) the Early Carboniferous rift mafic lavas from the Volcanics Unit were generated by a relatively low degree of partial melting of an asthenospheric OIB-type intraplate source; (2)younger (late Early Carboniferous, -324.8 Ma ago) mafic lavas from the Ophiolite Unit were formed in a relatively depleted MORB-like mantle source, located in the uppermost asthenosphere and then gradually mixed with melts from the asthenospheric OIB-like mantle. A slight interaction between asthenosphere-derived magmas and lithospheric mantle took place during ascent to the surface. Subsequently, the most depleted mafic lavas of the ophiolite assemblage were contaminated by upper-crustal components (seawater or carbonate crust).  相似文献   

山西中条山涑水杂岩中冷口变质火山岩的地球化学及构造环境     

赵风清 《地球科学与环境学报》1994,(2)

冷口变质火山岩为较典型的双峰式火山岩，以变质基性火山岩为主，夹变质英安质岩石。依据元素地球化学和同位素地球化学分析，它应形成于大陆或大陆边缘裂谷环境。基性岩浆来源于亏损地幔，岩浆在侵位过程中受到强烈的地壳成分混杂作用改造，而英安质岩石可能是由大陆地壳部分熔融作用形成的。  相似文献   

Nb/Ta variations of mafic volcanics on the Archean- Proterozoic boundary: Implications for the Nb/Ta imbalance     

LIU Yongsheng    GAO Shan    WANG Xuance  HU Shenghong & WANG Jianqi . State Key Laboratory of Geological Processes  Mineral Resources  China University of Geosciences  Wuhan  China  . Key Laboratory of Continental Dynamics  Department of Geology  Northwest University  Xi’an  China 《中国科学D辑(英文版)》2005,48(8):1106-1119

Hofmann[1] found that the depleted mantle (DM) and bulk continental crust (BCC) are simply compen-satory in terms of many elements and elemental ratios. High-field-strength elements (HFSE) (e.g., Zr, Hf, Nb, Ta and Ti) are immobile and thus useful to track the primary features of the ancient mafic volcanics. It has been long considered that Nb-Ta behave as identical twins during magmatic processes, based on their matching atomic radii and valence state and hence coherent geochemical affi…  相似文献   

北京西山大灰厂东狼沟组钾质火山岩形成的构造背景探讨   总被引：3，自引：1，他引：3  

汪洋姬广义  夏希凡 《城市地质》2005,17(3):1-10,22

北京西山大灰厂早白垩世东狼沟组火山岩为钾质粗面玄武岩、钾玄岩和安粗岩，总体属于严格意义的钾玄岩系列（橄榄安粗岩系列）。该套火山岩富集钾等大离子亲石元素（LILE）和轻稀土元素（LREE），是由于底侵幔源母岩浆在高压（1．2～1．5GPa，相当于42～50km深度）的岩浆房内经历结晶分离作用所致，母岩浆相对富钾也是原因之一。该火山岩形成于造山带开始发生崩塌的后碰撞阶段起始时期，在大地构造位置上处于中生代东亚大陆活动陆缘宽广的内带。深俯冲到250km或更深深度的大洋板片的脱水作用是诱发该火山岩地幔源区熔融的主要因素。东狼沟组钾玄岩的发育表明当时燕山存在约50km的厚地壳，古地形高度可达海拔3．9km。燕山中生代高原（高山）地貌和相应的气候条件可能为原始鸟类的形成演化提供了非常适宜的环境。  相似文献   

三个锆石U-Pb SHRIMP年龄对雄村特大型铜金矿床容矿火成岩时代的重新厘定   总被引：5，自引：5，他引：5  

曲晓明  辛洪波  徐文艺 《矿床地质》2007,26(5):512-518

位于冈底斯造山带中西段的雄村特大型铜金矿床产于日喀则弧前盆地北缘的旦狮庭组火山岩中。文章通过对雄村矿床矿体外围英安斑岩、矿带内花岗闪长斑岩脉和矿体深部花岗闪长斑岩3个样品的锆石U-Pb SHRIMP年龄测定,获得成岩年龄分别为(195±4.6)Ma(MSWD=1.48)、(179±5)Ma(MSWD=2.6)和(175±5)Ma(MSWD=3.2),表明这套火山岩是形成于早侏罗世而不是此前一致公认的晚白垩世。在已知成矿时代为始新世(38.11Ma)的情况下,这些早侏罗世容矿火山岩时代的确定自然就排除了该矿床属斑岩型或海底喷流沉积型成因的可能性。另外,矿床受NWW向断裂破碎带控制,缺少浅成低温热液矿床的蚀变矿化组合,成矿流体具有岩浆水与大气水混合特征,矿石硫化物与容矿火山岩具有一致的S、Pb同位素组成。这些成矿特征与胶东焦家式金矿具有很大的相似性,推测该矿床很可能属于破碎带蚀变岩型铜金矿床。  相似文献   

Petrology and geochemistry of Tertiary volcanic rocks from the İkizce (Ordu) area, NE Turkey: Implications for the evolution of the eastern Pontide paleo-magmatic arc     

&#x;. Temizel  M. Arslan 《Journal of Asian Earth Sciences》2008,31(4-6):439-463

Tertiary volcanism in the İkizce region at the western edge of the eastern Pontides paleo-magmatic arc is represented by basaltic and andesitic rocks associated with sediments deposited in a shallow basin environment. The basaltic rocks contain plagioclase (An_58–80), olivine (Fo_82–84), clinopyroxene (Wo_44–48En_35–42Fs_7–17), hornblende (Mg# = 0.68–0.76) phenocrysts, and magnetite microcrysts, whereas the andesitic rocks include plagioclase (An_25–61), clinopyroxene (Wo_46–49En_38–43Fs_11–13), hornblende (Mg# = 0.48–0.81), biotite (Mg# = 0.48–0.60) phenocrysts, titanomagnetite, apatite, and zircon microcrysts.Geochemical data indicate magmatic evolution from tholeiitic-alkaline transitional to calc-alkaline characteristics with medium-K contents. The geochemical variation in the rocks can be explained by fractionation of common mineral phases such as clinopyroxene, olivine, hornblende, plagioclase, magnetite, and apatite. The trace elements’ distributions of the volcanic rocks show similarities to those of E-Type MORB, have a shape that is typical of rocks from subduction-related tectonic setting with enrichment in LILE and to a lesser extent in LREE, but depletion in HFSE. The rocks evolved from a parental magma derived from an enriched source formed by subduction induced metasomatism of basaltic rocks, the latter formed through clinopyroxene ± olivine controlled fractionation in a high level magma chamber. The andesitic rocks developed through hornblende ± plagioclase controlled fractionation in shallow level magma chamber(s).  相似文献   

阿尔泰麦兹地区海相火山岩及其与成矿作用的关系   总被引：2，自引：0，他引：2  

张进红  王京彬  丁汝福 《地质论评》1999,45(7):1116-1125

阿尔泰麦兹地区下泥盆统康布铁堡组火山岩,下亚组为偏碱性的富钠流纹岩夹少量的拉斑—碱性玄武岩和粗安岩;上亚组为钙碱性流纹岩类。其构造环境为大陆边缘活化带。下亚组基性火山岩来源于过渡—富集型地幔,酸性火山岩为壳幔混合源,岩浆经历了结晶分异、岩浆混合和岩浆不混熔作用;上亚组酸性火山岩来源于地壳,岩浆演化主要为与上地壳和海水的同化混染作用。本文还探讨了火山岩与铁和铅锌成矿作用的关系。  相似文献