TRIASSIC SEQUENCE STRATIGRAPHY AND CORRELATION FROM POLY-ARC AND BACK-ARC SYSTEM IN EASTERN TIBET     

Peng Yongming  Pan Guitang  Luo Jiangning  Wan Minjie 《地学前缘》2000,(Z1)

TRIASSIC SEQUENCE STRATIGRAPHY AND CORRELATION FROM POLY-ARC AND BACK-ARC SYSTEM IN EASTERN TIBET  相似文献   

江达—维西陆缘火山弧的形成演化及成矿作用   总被引：16，自引：0，他引：16       下载免费PDF全文

王立全  潘桂棠  李定谋  须同瑞 《沉积与特提斯地质》2000,20(2):1-17

江达－维西陆缘火山弧为金沙江弧后洋盆向西俯冲消减和斜向碰撞过程中形成,其过程经历了俯冲造弧－碰撞成弧－张裂成盆的复杂发展历史。早二叠世晚期－晚二叠世（Ｐ＾２１－Ｐ２）形成储冲型弧火山岩,早中三叠世（Ｔ１＋２）形成碰撞型弧火山岩,晚三叠世早期（Ｔ＾１３）于裂谷盆地中发育“双峰式”火山岩。晚三叠世早期（Ｔ＾１３）裂谷分国地从北向南形成生达－车所－鲁麻弧后盆地、徐中－鲁春－红坡上叠（弧后）裂谷盆地和箐口  相似文献   

川西义敦地区三叠纪层序地层研究新认识          下载免费PDF全文

黄仕华 《沉积与特提斯地质》2000,20(2)

义敦地区处于活动岛弧带 ,1:5万区调将原图姆沟组自下而上分解为党恩组、列衣组、曲嘎寺组和勉戈组。以曲嘎寺组底部的I型不整合面及勉戈组底部的II型不整合面为基准 ,结合内部沉积组合特征 ,尝试划分出 3套三级层序地层 ,即下部层序 (未见底 )、中部I型碳酸盐层序和上部II型层序 (包括喇嘛垭组 ) ,在这些层序内各体系域发育齐全 ,特征明显。  相似文献   

西地中海的弧后盆地     

刘建华 《海洋学研究》2000,18(2):15-24

地中海是太平洋之外弧后盆地较为发育的海区。巴利阿里海盆和第勒尼安海盆是西地中海两个位置相邻、互有成因联系的弧后盆地。海盆莫霍面埋深分别为 1 2～ 1 5km和 1 0 km,热流密度分别为 1 0 0 m W/m2和 2 0 0 m W/m2 ,发育有大洋型磁条带异常 ,大洋钻探和拖网取样均采到了拉斑玄武岩。较之巴利阿里海盆 ,第勒尼安海盆更富年青性。两弧后盆地的成生演化是与欧洲板块与非洲 -阿普利亚板块的相互作用息息相关的。中新世 ,随着非洲 -阿普利亚板块向西、西北俯冲 ,科西嘉、撒丁裂离欧洲大陆 ,巴利阿里海盆被打开 ;上新世 ,阿普利亚微板块进一步俯冲 ,导致亚平宁与科西嘉、撒丁之间的裂离 ,形成第勒尼安海盆。  相似文献   

台湾南部恒春海脊地质地球物理特征及其大地构造属性     

王平  夏戡原  黄慈流 《热带海洋学报》2000,19(3):33-39

恒春海脊的地质、地球物理特征与其相邻的南海海盆、吕宋火山弧和北吕宋海槽等地质构造单元所反映的特征明显不同 ,主要表现为低密度、弱磁性。推测其地壳性质为陆壳 ,是恒春半岛的南延部分。海脊西侧缓坡为陆缘增生楔 ,可见刺穿现象 ,这些刺穿构造是由逆冲挤压引起的泥底辟。海脊东部受弧陆碰撞的影响而急剧抬升。东部的弧陆碰撞是海脊抬升和增生楔形成的主要原因  相似文献   

西藏纳木错西岸蛇绿岩的地球化学特征及其形成环境   总被引：14，自引：4，他引：10  

叶培盛  吴珍汉  胡道功  江万  杨欣德 《现代地质》2004,18(2):237-243

西藏纳木错西岸蛇绿岩主要由变质橄榄岩、辉长辉绿岩及玄武岩等组成。变质橄榄岩以富Mg、贫Ti、贫REE元素为特征。辉绿岩和玄武岩的主量元素、微量元素特征显示其含有洋脊拉斑玄武岩和岛弧拉斑玄武岩的双重成分,其中高场强元素Nb、Ta、Zr、Hf等亏损．大离子亲石元素Rb、Sr、Ba等相对富集,具岛弧玄武岩的特点;在球粒陨石标准化稀土元素配分模式图上为LREE亏损的平坦型,无负Eu异常,与洋中脊玄武岩的特征类似。通过与典型地区作对比并应用构造环境判别图解,推测该区蛇绿岩形成于弧后盆地的构造环境。  相似文献   

Saraçköy Volcanic Suite: implications for the subductional phase of arc evolution in the Galatean Arc Complex,Ankara, Turkey     

Ali&#x; Koyi&#x;i&#x;t  John Alan Winchester  Erdi&#x;n Bozkurt  Grenville Holland 《Geological Journal》2003,38(1):1-14

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Lithium isotope variations in Tonga–Kermadec arc–Lau back‐arc lavas and Deep Sea Drilling Project (DSDP) Site 204 sediments     

Raul Brens  Xiao‐Ming Liu  Simon Turner  Tracy Rushmer 《Island Arc》2019,28(1)

Lithium isotopes have been identified as a promising tracer of subducted materials in arc lavas due to the observable variations in related reservoirs such as subducting sediments and altered oceanic crust. The Tonga–Kermadec arc–Lau back‐arc provides an end‐member of subduction zones with the coldest thermal structure on Earth. Reported here are Li isotope data for 14 lavas from the arc front and 7 back‐arc lavas as well as 12 pelagic and volcaniclastic sediments along a profile through the sedimentary sequence at DSDP Site 204. The arc and back‐arc lavas range from basalts to dacites in composition with SiO₂ = 48.3–65.3 wt% over which Li concentrations increase from 2 ppm to 16 ppm. Li/Y ratios range from 0.08 to 0.77 and from 0.24 to 0.65 in the arc and back‐arc lavas, respectively. The majority of the lavas have δ⁷Li that ranges from 2.5 ‰ to 5.0 ‰ with an average of (3.6 ±0.7) ‰, similar to that reported from other arcs and there is no distinction between the arc front and back‐arc lavas. The pelagic sediments have variable Li concentrations (33–133 ppm) and δ⁷Li that ranges from 1.2 ‰ to 10.2 ‰ while the volcaniclastic sediments have an even greater range of Li concentrations (3.6–165 ppm) and generally higher δ⁷Li values (8–14 ‰). However, δ⁷Li in the lavas does not correlate with commonly used trace element ratio or isotope signatures indicative of slab‐derived fluids or the sediments. This is probably because the range of δ⁷Li in the lavas and sediments overlap. Calculated sediment mass‐balance models require significantly more sediment than previous estimates based on Th–Nd–Be isotopes. This may indicate that a sizeable proportion of the total Li budget in the lavas is provided by Li‐enriched fluids from the subducting sediments and/or altered oceanic crust.  相似文献   

Crustal structure and origin of the northeast Japan arc   总被引：1，自引：0，他引：1  

Koji  Minoura Akira  Hasegawa 《Island Arc》1992,1(1):2-15

Abstract Northeast Japan is a typical island arc region and its topographic arrangement reflects the geophysical characteristics of the island arc system. However, the structural style of the arc is very complicated and varied due to the repeated superposing of faults and folds on to earlier structures.
Geotectonic events that involved creation of the fundamental framework of the island arc crust occurred in east Asia in the Late Jurassic to Early Cretaceous and were probably induced by accretion and collision tectonics. The fragmentation and subsequent displacement of the crust took place during the Early Neogene in response to the terrane collision and the change in oceanic plate motion, leading to the opening of the Japan Sea. Huge amounts of volcano-sedimentary rocks buried the tilted fault blocks of pre-Tertiary basement with the development of the island arc.  相似文献   

东天山接触交代型铁矿成矿时代的确定及其意义   总被引：2，自引：0，他引：2  

邓松涛  郭召杰  张志诚 《地质与勘探》2006,42(6):17-20

通过对东天山接触交代型铁矿中透闪石单矿物进行40Ar/39Ar年龄测定,获得坪年龄(387.21±0.68)Ma和等时线年龄(389.65±1.46)Ma.初步认为,此类接触交代型铁矿的成矿时代为387Ma左右.结合区域构造背景,可以认为,在早古生代东天山处于洋壳俯冲-消减产生的陆缘弧环境下,大规模构造岩浆活动是前寒武系中铁元素富集的主要动力,也是形成接触交代型铁矿的主要控制因素之一.  相似文献