期刊文献+
共找到56篇文章
< 1 2 3 >
每页显示 20 50 100
华北东部橄榄岩与岩石圈减薄中的地幔伸展和侵蚀置换作用 被引量:61
1
作者 郑建平 路凤香 +4 位作者 W L GRIFFIN 余淳梅 张瑞生 袁晓萍 吴秀玲 《地学前缘》 EI CAS CSCD 北大核心 2006年第2期76-85,共10页
对比分析了华北不同时代捕虏体橄榄岩及其南部超高压地质体橄榄岩的矿物化学。具古老难熔岩石圈地幔特征的橄榄岩是古生代金伯利岩捕虏体和早中生代苏鲁变质带地质体的主要岩石类型。具这一性质的橄榄岩也构成了河南鹤壁上新世玄武岩捕... 对比分析了华北不同时代捕虏体橄榄岩及其南部超高压地质体橄榄岩的矿物化学。具古老难熔岩石圈地幔特征的橄榄岩是古生代金伯利岩捕虏体和早中生代苏鲁变质带地质体的主要岩石类型。具这一性质的橄榄岩也构成了河南鹤壁上新世玄武岩捕虏体的主体部分,并可以在辽宁阜新晚中生代玄武岩中被发现。具饱满岩石圈地幔性质的橄榄岩则是阜新晚中生代火山岩、特别是郯庐断裂带(山旺)及其附近地区(栖霞)中新世玄武岩捕虏体的主要类型。从华北东部已有的捕虏体橄榄岩及地质体橄榄岩所表现出的新生饱满与古老难熔地幔的时、空分布特点,即有些地区捕虏体橄榄岩表现出不同性质地幔共存现象(如阜新、鹤壁)或橄榄石Mg#呈渐变关系看:克拉通岩石圈地幔因扬子板块俯冲所引起的早期(如早中生代)地幔伸展、和晚中生代—渐新世因太平洋俯冲所引起的热扰动的软流圈物质上涌对古老地幔产生强烈的侵蚀作用(引起岩石圈的巨大减薄);中新世以来的软流圈热沉降作用出现新生岩石圈地幔并表现为岩石圈的小幅增厚,从而实现地幔置换过程和华北东部岩石圈的整体减薄过程。岩石圈幔内薄弱带及岩石圈深断裂(如郯庐断裂带)起了软流圈物质侵蚀古老岩石圈地幔的通道作用并导引着深部物质运移和不规则减薄作用等。个别地区(如阜新)强烈的软流圈上涌于晚中生代就已经开始,显示地幔置换作用的强烈不均一性。 展开更多
关键词 橄榄岩 捕虏体 地质体 岩石圈减薄 地幔置换作用 伸展与侵蚀 华北东部
下载PDF
西部华夏地区深部可能存在与华北和扬子大陆相似的太古代基底 被引量:15
2
作者 郑建平 Griffin WL +3 位作者 汤华云 张志海 苏玉平 刘观亮 《高校地质学报》 CAS CSCD 北大核心 2008年第4期549-557,共9页
华夏地区是否存在古陆是一个长期争论的问题。火山作用的天然超深钻取样,提供了探索大陆基底属性和形成演化过程的重要手段。西部华夏地区地表所出露的最古老岩石不老于中元古代,但对广西省东南部晚中生代—新生代火山岩中锆石捕虏晶的U... 华夏地区是否存在古陆是一个长期争论的问题。火山作用的天然超深钻取样,提供了探索大陆基底属性和形成演化过程的重要手段。西部华夏地区地表所出露的最古老岩石不老于中元古代,但对广西省东南部晚中生代—新生代火山岩中锆石捕虏晶的U-Pb年代学和Lu-Hf同位素研究则表明:与华北和扬子大陆相似,西部华夏地区有未暴露的太古代基底。该基底的主体年龄是2.9-2.5Ga,也有3.85Ga,3.55Ga和3.3-3.2Ga的年龄等。它们的亏损地幔模式年龄(tDM)为2.5Ga至≥3.9Ga。说明西部华夏地区的基底经历了复杂的改造过程,包括3.6-3.2Ga,2.5Ga,1.0Ga和0.5Ga时的地幔物质加入,以及2.0-1.8Ga和1.6-1.5Ga时的地壳再熔融事件等。对西部华夏地区强烈改造岩石圈的认识,将有助于从物质组分角度对华南成矿作用背景的思考。华夏地区是否存在古陆是一个长期争论的问题。火山作用的天然超深钻取样,提供了探索大陆基底属性和形成演化过程的重要手段。西部华夏地区地表所出露的最古老岩石不老于中元古代,但对广西省东南部晚中生代—新生代火山岩中锆石捕虏晶的U-Pb年代学和Lu-Hf同位素研究则表明:与华北和扬子大陆相似,西部华夏地区有未暴露的太古代基底。该基底的主体年龄是2.9-2.5Ga,也有3.85Ga,3.55Ga和3.3-3.2Ga的年龄等。它们的亏损地幔模式年龄(tDM)为2.5Ga至≥3.9Ga。说明西部华夏地区的基底经历了复杂的改造过程,包括3.6-3.2Ga,2.5Ga,1.0Ga和0.5Ga时的地幔物质加入,以及2.0-1.8Ga和1.6-1.5Ga时的地壳再熔融事件等。对西部华夏地区强烈改造岩石圈的认识,将有助于从物质组分角度对华南成矿作用背景的思考。 展开更多
关键词 西部华夏 太古代基底 改造作用 锆石 捕虏晶
下载PDF
华北克拉通中部地区背景噪声成像 被引量:43
3
作者 唐有彩 陈永顺 +10 位作者 杨英杰 丁志峰 刘瑞丰 冯永革 李鹏 俞春泉 魏松峤 范文渊 王海洋 周仕勇 宁杰远 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2011年第8期2011-2022,共12页
利用华北地区的流动与固定地震观测台阵在2007年1月~12月期间的垂直分量记录,采用背景噪声层析成像方法获得了华北克拉通中部地区6~40 s的相速度和群速度分布图像.成像结果显示研究区地壳以及上地幔的速度结构存在很大的横向不均匀性.... 利用华北地区的流动与固定地震观测台阵在2007年1月~12月期间的垂直分量记录,采用背景噪声层析成像方法获得了华北克拉通中部地区6~40 s的相速度和群速度分布图像.成像结果显示研究区地壳以及上地幔的速度结构存在很大的横向不均匀性.8~16 s的相速度以及8~20 s的群速度分布图像清晰地勾绘出华北地区盆地和隆起之间的边界.华北盆地以及山西断陷带呈明显的低速异常,表明相应区域存在较厚的沉积层并且在中、上地壳内存在低速带;而太行山隆起以及鄂尔多斯高原则呈现高速异常.相速度16~25 s以及群速度20~30 s的图像显示华北盆地由低速异常变为高速异常,表明华北盆地的地壳较薄.长周期(30~35 s)相速度图像表明华北盆地的上地幔顶部存在低速异常.华北盆地较薄的地壳和低速异常(明显低于全球平均水平),可能与该地区岩石圈减薄,软流圈物质上涌有关.8~35 s的群速度和相速度图像都显示,大同火山区是一个低速异常区,可能是由目前仍在活动的岩浆的加热而引起地壳升温造成的. 展开更多
关键词 背景噪声层析成像 华北盆地 鄂尔多斯 山西断陷带 群速度 相速度
下载PDF
大陆岩石圈有效弹性厚度的计算及其地质意义 被引量:9
4
作者 袁炳强 Yvette H.Poudjom Djomani +1 位作者 程顺有 陆关祥 《地球学报》 EI CAS CSCD 北大核心 2002年第3期269-272,共4页
大陆范围内Te值有很大的范围 ,不同构造单元有不同的Te值。Te值的大小与岩石圈的热结构 (热年龄 )、壳幔耦合等因素有关。同时Te值和地壳厚度、地表有关矿产的分布。
关键词 大陆岩石圈 有效弹性厚度 计算 地质意义
下载PDF
北羌塘新生代火山岩长石矿物激光探针原位测试及其微量元素特征初探 被引量:18
5
作者 赖绍聪 刘池阳 +2 位作者 伊海生 S.Y.O’Reilly 张明 《地质科学》 CAS CSCD 北大核心 2003年第4期539-545,共7页
利用电子探针和激光探针剥蚀系统 (LA ICP MS) ,对北羌塘半岛湖新第三纪粗面安山岩中的碱性长石和斜长石进行了系统分析 ,讨论了激光探针原位 (insitu)测试方法的有关细节及其对暗色矿物和浅色矿物的耦合性。在此基础上分析归纳了本区... 利用电子探针和激光探针剥蚀系统 (LA ICP MS) ,对北羌塘半岛湖新第三纪粗面安山岩中的碱性长石和斜长石进行了系统分析 ,讨论了激光探针原位 (insitu)测试方法的有关细节及其对暗色矿物和浅色矿物的耦合性。在此基础上分析归纳了本区长石矿物中痕量元素及稀土元素地球化学性状。结果表明 ,长石中强烈地富集了Rb、Sr、Ba和Eu ,在两类长石中 ,无论是大离子亲石元素还是稀土元素 ,均未显示明显的选择性富集规律。 展开更多
关键词 常量元素 微量元素 长石 新生代火山岩
下载PDF
北冰洋-欧亚大陆-太平洋地学断面东南段岩石圈有效弹性厚度 被引量:8
6
作者 袁炳强 Yvette H.Poudjom Djomani +2 位作者 王平 袁学诚 左愚 《地球科学(中国地质大学学报)》 EI CAS CSCD 北大核心 2002年第4期397-402,共6页
大陆岩石圈有效弹性厚度 (Te)是表示岩石圈强度的参数 ,计算该参数对研究岩石圈大规模构造 ,分析大陆板块内的均衡补偿机制有一定意义 .利用Forsyth提出的相关技术计算了北冰洋 -欧亚大陆 -太平洋地学断面东南段自黑水到泉州的Te 值 .... 大陆岩石圈有效弹性厚度 (Te)是表示岩石圈强度的参数 ,计算该参数对研究岩石圈大规模构造 ,分析大陆板块内的均衡补偿机制有一定意义 .利用Forsyth提出的相关技术计算了北冰洋 -欧亚大陆 -太平洋地学断面东南段自黑水到泉州的Te 值 .并分析了重力和地形波长的相关性特征 ,初步认为 :计算Te 值所选的每个数据块在短波长 (6 .6~ 10 0km)内岩石圈板块的强度足以平衡地形负载 ,重力和地形不相关 ;在长波长 (10 0~ 2 5 0km)内 ,地形及地下负载由弯曲模型补偿 ,岩石圈板块在地形及地下负载作用下而挠曲 .断面通过地段具有较低热流密度值的四川陆核有较高的Te 值 ,具有较高热流密度值的宁化、大田地区有较低的Te 值 ,反映了较高的热流密度值对应较低的Te 值 ;较低的热流密度值对应较高Te 值的关系 .Te 可分为南东低值段和北西高值段 .地壳厚度大体上与Te 值呈正相关关系 . 展开更多
关键词 岩石圈 有效弹性厚度 北冰洋-欧亚大陆-太平洋地学断面 大陆板块 重力 地形 均衡补偿机制
下载PDF
汉诺坝橄榄岩捕虏体的单斜辉石LAM-ICPMS分析及其岩石圈地幔演化意义 被引量:16
7
作者 余淳梅 郑建平 W.L.Griffin 《地球科学(中国地质大学学报)》 EI CAS CSCD 北大核心 2006年第1期93-100,共8页
橄榄岩成分及其中矿物(如单斜辉石)微量元素组成可以很好地揭示岩石圈地幔性质.在对汉诺坝新生代玄武岩中橄榄岩捕虏体做详细岩相学和岩石化学研究基础上,重点分析了单斜辉石的激光原位微量元素,并探讨了新生代华北克拉通北缘岩石圈地... 橄榄岩成分及其中矿物(如单斜辉石)微量元素组成可以很好地揭示岩石圈地幔性质.在对汉诺坝新生代玄武岩中橄榄岩捕虏体做详细岩相学和岩石化学研究基础上,重点分析了单斜辉石的激光原位微量元素,并探讨了新生代华北克拉通北缘岩石圈地幔特征及地幔演化.汉诺坝地区岩石圈地幔是相当于原始地幔经过不同程度的部分熔融抽取形成的,除个别样品的部分熔融程度为15%-20%外,多数样品<5%.全岩主元素、单斜辉石成分体现出新生代汉诺坝地区的岩石圈地幔是很不均一的:在主体饱满型中有亏损型地幔的残留.这种共存现象可能是软流圈物质对古老地幔进行侵蚀、混合和改造置换的结果.单斜辉石微量元素组成所体现的碳酸岩岩浆交代作用和硅酸盐熔/流体的交代作用也支持这一认识. 展开更多
关键词 橄榄岩捕虏体 单斜辉石 LAM—ICPMS 岩石圈地幔演化 汉诺坝 华北克拉通
下载PDF
雷州英峰岭玄武岩中单斜辉石巨晶的地球化学和地幔交代作用 被引量:11
8
作者 于津海 O'Reilly Y S 周新民 《岩石学报》 SCIE EI CAS CSCD 北大核心 2003年第4期637-649,共13页
雷州半岛英峰岭火山岩中单斜辉石巨晶以低Mg#值(0.62~0.47)、贫重稀土(HREE)和富Al2O3、TiO2、Na2O和中稀土(MREE)为特征,并具有明显的成分变化.随着Mg#降低,单斜辉石的Al2O3(11.58~6.97%)、TiO2(2.28~1.06%)和HREE逐渐降低.这种变... 雷州半岛英峰岭火山岩中单斜辉石巨晶以低Mg#值(0.62~0.47)、贫重稀土(HREE)和富Al2O3、TiO2、Na2O和中稀土(MREE)为特征,并具有明显的成分变化.随着Mg#降低,单斜辉石的Al2O3(11.58~6.97%)、TiO2(2.28~1.06%)和HREE逐渐降低.这种变化特征不同于世界上大多数辉石巨晶的变化规律.随着演化辉石巨晶的大多数不相容元素,如Nb、Sr、Zr、Hf和LREE-MREE逐渐增加.低的Mg#值和Ni、Co、Cr含量指示巨晶母岩浆是一种强烈演化的残余岩浆(Mg#=0.27~0.35).分离结晶模拟表明本研究最富镁的巨晶(Lz-54)的母岩浆很可能是由拉斑玄武质岩浆经70~80%以单斜辉石为主的结晶分异后形成.而本研究的其它辉石巨晶是该母岩浆在不同演化阶段(25~80%)分离结晶的产物.分离矿物中除了单斜辉石还包含了大量的石榴子石、斜长石和钛铁矿.温压计算表明英峰岭巨晶是高温岩浆在56~60km深的上地幔的结晶产物(T=1290℃~1130℃,P=1.73~1.83GPa),这一深度有利于石榴子石结晶.对比不同地区辉石巨晶的成分特征和形成条件,作者指出不同地区单斜辉石巨晶各种元素的不同变化规律主要受母岩浆成分和结晶条件控制.巨晶母岩浆在地幔结晶时对围岩橄榄岩进行了不同程度的交代作用.早期贫流体的岩浆对橄榄岩的交代作用较弱,只有Sr,La等强活动性元素被明显改变;晚期富流体(F,P,H2O)岩浆对橄榄岩的交代作用强烈,大多数元素被明显改变.因此,可以推断交代熔体中流体的含量是影响地幔橄榄岩交代作用的关键. 展开更多
关键词 单斜辉石巨晶 地球化学 地慢交代作用 雷州半岛
下载PDF
青藏高原北羌塘半岛湖新生代粗面玄武岩橄榄石电子探针和激光探针分析 被引量:6
9
作者 赖绍聪 伊海生 +1 位作者 刘池阳 O’Reilly S Y 《矿物学报》 CAS CSCD 北大核心 2002年第2期107-112,共6页
利用电子探针和激光探针剥蚀系统 (LA ICP MS) ,对北羌塘新第三纪粗面玄武岩中的橄榄石主元素和微量、稀土元素进行了系统分析。结果表明 ,本区橄榄石Fo平均为 88,属贵橄榄石种属。相对富集Ni、Co和重稀土 ,而强烈亏损轻稀土及Rb、Sr、B... 利用电子探针和激光探针剥蚀系统 (LA ICP MS) ,对北羌塘新第三纪粗面玄武岩中的橄榄石主元素和微量、稀土元素进行了系统分析。结果表明 ,本区橄榄石Fo平均为 88,属贵橄榄石种属。相对富集Ni、Co和重稀土 ,而强烈亏损轻稀土及Rb、Sr、Ba、Zr等大离子亲石元素。其稀土元素配分型式与粗面玄武岩全岩稀土配分型式呈互补状态。 展开更多
关键词 青藏高原 橄榄石 微量元素 新生代 火山岩 玄武岩 电子探针 激光探针
下载PDF
大别造山带碧溪岭橄榄岩中锆石U-Pb年龄和Hf同位素研究 被引量:4
10
作者 郑建平 孙敏 +3 位作者 Griffin WL 钟增球 汤华云 张志海 《岩石学报》 SCIE EI CAS CSCD 北大核心 2007年第2期343-350,共8页
在详细形态和内部结构研究基础上,对碧溪岭橄榄岩锆石进行了配套的U-Pb年龄和Hf同位素分析。碧溪岭橄榄岩锆石主体是变质成因的,但有少量岩浆锆石残留。这些锆石主体给出了220~210Ma的变质生长/重结晶作用年龄;一颗具较高Th/U比值的锆... 在详细形态和内部结构研究基础上,对碧溪岭橄榄岩锆石进行了配套的U-Pb年龄和Hf同位素分析。碧溪岭橄榄岩锆石主体是变质成因的,但有少量岩浆锆石残留。这些锆石主体给出了220~210Ma的变质生长/重结晶作用年龄;一颗具较高Th/U比值的锆石给出646Ma的近协和年龄,限定了早期岩浆结晶作用的最小年龄。真正的侵位年龄可以由745Ma的上交点年龄来限定;210~222Ma则记录着深俯冲陆壳折返过程中的锆石生长。除少数颗粒的ε_(Hf)为负值外(-2.9),大部分锆石的ε_(Hf)是正的(高达+8.1)并具新元古代的亏损地幔模式年龄(0.6~1.0Ga,平均0.8Ga)。这些结果说明碧溪岭橄榄岩的初始物质是扬子大陆岩石圈内新元古代岩浆堆积作用产物。这样的岩浆堆积物来源于亏损的软流圈地幔,侵入于扬子的深部地壳之中(如底侵)并部分混染了古老地壳组分。它们随扬子向华北之下深俯冲碰撞和造山带折返过程中经历着复杂的变质改造作用。 展开更多
关键词 橄榄岩锆石 年龄和Hf同位素 新元古代底侵 扬子地块 早中生代折返 大别造山带 碧溪岭
下载PDF
华北克拉通西部陆块北缘新生代岩石圈地幔特征的初步研究 被引量:9
11
作者 王亚妹 William L GRIFFIN +2 位作者 韩宝福 WANG YaMei HAN BaoFu 《岩石学报》 SCIE EI CAS CSCD 北大核心 2011年第10期2912-2926,共15页
凉城、四子王旗、三义堂和大同的地幔包体的岩石学和矿物的主、微量元素成分显示华北克拉通中、西部北缘总体为过渡型岩石圈地幔,为原始地幔经过不同程度的熔体抽取和后期交代富集作用的残留。凉城岩石圈地幔经历的熔体抽取程度最低,后... 凉城、四子王旗、三义堂和大同的地幔包体的岩石学和矿物的主、微量元素成分显示华北克拉通中、西部北缘总体为过渡型岩石圈地幔,为原始地幔经过不同程度的熔体抽取和后期交代富集作用的残留。凉城岩石圈地幔经历的熔体抽取程度最低,后期交代富集作用比较强烈,这与其橄榄岩中尖晶石的Cr#较低,并且共存的单斜辉石的Mg#较低一致。三义堂岩石圈地幔经历的熔体抽取程度最高,后期交代富集作用最强烈,不同样品甚至同一样品中不同单斜辉石颗粒的La/Yb和LREE配分模式变化范围非常大,且矿物边部比核部更富集微量元素。大同、四子王旗岩石圈地幔经历的熔体抽取程度介于凉城和三义堂之间,但后期的交代富集作用明显不如凉城和三义堂强烈。研究区的岩石圈地幔主要受硅酸盐熔体交代作用的影响,只有三义堂岩石圈地幔还可能也受到了碳酸盐交代作用的影响。 展开更多
关键词 岩石圈地幔 地幔包体 西部陆块 华北克拉通
下载PDF
大陆岩石圈演化的新视角——大洋玄武岩和蛇绿岩Re-Os同位素体系记录的SCLM信息 被引量:1
12
作者 史仁灯 支霞臣 +2 位作者 O Alard S O'Reilly W Griffin 《矿物岩石地球化学通报》 CAS CSCD 2007年第z1期24-25,共2页
  在Re-Os同位素体系应用于蛇绿岩研究之前,一直认为蛇绿岩的地幔橄榄岩是古大洋岩石圈地幔的残留.近年来,随着Re-Os同位素测试技术的提高和广泛运用,在现代大洋以及蛇绿岩中均发现有古老大陆岩石圈地幔(SCLM)的信息.……
关键词 RE-OS同位素 蛇绿岩 大陆岩石圈
下载PDF
U and Th Contents and Th/U Ratios of Zircon in Felsic and Mafic Magmatic Rocks:Improved Zircon-Melt Distribution Coefficients 被引量:19
13
作者 WANG Xiang Williams L. GRIFFIN +2 位作者 CHEN Jie HUANG Pinyun LI Xiang 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2011年第1期164-174,共11页
High-precision data on U and Th contents and Th/U ratios of zircon obtained using secondary ion mass spectrometry analysis have been collected from the literature. Zircon in the granitic rocks has median values of 350... High-precision data on U and Th contents and Th/U ratios of zircon obtained using secondary ion mass spectrometry analysis have been collected from the literature. Zircon in the granitic rocks has median values of 350 ppm U, 140 ppm Th, and Th/U=0.52; the recommended zircon-melt partition coefficients are 81 for Du and 8.2 for DTh. In zircon from mafic and intermediate rocks, the median values are 270 ppm U, 170 ppm Th, and Th/U=0.81, and the recommended zirconmelt partition coefficients are 169 for Du and 59 for DTh. The U and Th contents and Th/U ratios of magmatic zircon are low when zircon crystallizes in equilibrium with the melt. Increasing magma temperature should promote higher Th contents relative to U contents, resulting in higher Th/U ratios for zircon in mafic to intermediate rocks than in granitic rocks. However, when zircon crystallizes in disequilibrium with the melt, U and Th are more easily able to enter the zircon lattice, and their contents and Th/U ratios depend mainly on the degree of disequilibrium. The behavior of U and Th in magmatic zircon can be used as a geochemical indicator to determine the origins and crystallization environments of magmatic zircon. 展开更多
关键词 ZIRCON Th/U ratio granitic rock mafic to intermediate rock zircon-melt distributioncoefficient
下载PDF
Surface wave tomography on a large-scale seismic array combining ambient noise and teleseismic earthquake data 被引量:3
14
作者 Yingjie Yang Weisen Shen Michael H. Ritzwoller 《Earthquake Science》 CSCD 2011年第1期55-64,共10页
We discuss two array-based tomography methods, ambient noise tomography (ANT) and two-plane- wave earthquake tomography (TPWT), which are capable of taking advantage of emerging large-scale broadband seismic array... We discuss two array-based tomography methods, ambient noise tomography (ANT) and two-plane- wave earthquake tomography (TPWT), which are capable of taking advantage of emerging large-scale broadband seismic arrays to generate high resolution phase velocity maps, but in complementary period band: ANT at 8-40 s and TPWT at 25-100 s period. Combining these two methods generates surface wave dispersion maps from 8 to 100 s periods, which can be used to construct a 3D vs model from the surface to -200 km depth. As an illustration, we apply the two methods to the USArray/Transportable Array. We process seismic noise data from over 1 500 stations obtained from 2005 through 2009 to produce Rayleigh wave phase velocity maps from 8 to 40 s period, and also perform TPWT using -450 teleseismic earthquakes to obtain phase velocity maps between 25 and 100 s period. Combining dispersion maps from ANT and TPWT, we construct a 3D vs model from the surface to a depth of 160 km in the western and central USA. These surface wave tomography methods can also be applied to other rapidly growing seismic networks such as those in China. 展开更多
关键词 ambient noise Rayleigh wave surface wave tomography
下载PDF
Genesis of the Gold Deposit in the Indus-Yarlung Tsangpo Suture Zone,Southern Tibet:Evidence from Geological and Geochemical Data 被引量:5
15
作者 ZHANG Xiong DENG Xueguo +9 位作者 YANG Zhusen HOU Zengqian ZHENG Yuanchuan LIU Yingchao ZHAO Xiaoyan XU Bo PEI Yingru ZHOU Jinsheng ZHAO Miao YUAN Jianfei 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2017年第3期947-970,共24页
The Nianzha gold deposit, located in the central section of the Indus-Yarlung Tsangpo suture (IYS) zone in southern Tibet, is a large gold deposit (Au reserves of 25 tons with average grade of 3.08 g/t) controlled... The Nianzha gold deposit, located in the central section of the Indus-Yarlung Tsangpo suture (IYS) zone in southern Tibet, is a large gold deposit (Au reserves of 25 tons with average grade of 3.08 g/t) controlled by a E-W striking fault that developed during the main stage of Indo-Asian collision (-65-41 Ma). The main orebody is 1760 m long and 5.15 m thick, and occurs in a fracture zone bordered by Cretaceous diorite in the hanging wall to the north and the Renbu tectonic melange in the footwall to the south. High-grade mineralization occurs in a fracture zone between diorite and ultramafic rock in the Renbu tectonic melange. The wall-rock alteration is characterized by silicification in the fracture zone, serpentinization and the formation of talc and magnesite in the uitramafic unit, and chloritization and the formation of epidote and calcite in diorite. Quartz veins associated with Au mineralization can be divided into three stages. Fluid inclusion data indicate that the deposit formed from H20-NaCl-organic gas fluids that homogenize at temperatures of 203℃-347℃ and have salinities of 0.35wt%-17.17wt% NaCI equivalent. The quartz veins yield δ18Ofluid values of 0.15‰-10.45‰, low δDv-SMow values (-173%o to -96%o), and the δ13C values of-17.6‰ to -4.7‰, indicating the ore-forming fluids were a mix of metamorphic and sedimentary orogenic fluids with the addition of some meteoric and mantle-derived fluids. The pyrite within the diorite has δ34SV-CDT values of -2.9‰-1.9‰(average -1.1‰), 206pb/204pb values of 18.47- 18.64, 207pb/204pb values of 15.64-15.74, and 208pb/204pb values of 38.71-39.27, all of which are indicative of the derivation of S and other ore-forming elements from deep in the mantle. The presence of the Nianzha, Bangbu, and Mayum gold deposits within the IYS zone indicates that this area is highly prospective for large orogenic gold deposits. We identified three types of mineralization within the IYS, namely Bangbu-type accretionary, Mayum-type microcontinent, and Nianzha-type ophiolite-associated orogenic Au deposits. The three types formed at different depths in an aeeretionary orogenic tectonic setting. The Bangbu type was formed at the deepest level and the Nianzha type at the shallowest. 展开更多
关键词 GEOLOGY gold mineralization Nianzha Deposit Indus-Yarlung Tsangpo suture zone TIBET
下载PDF
Petrography and Geochemistry of Peridotite Xenoliths from Hannuoba and Significance for Lithospheric Mantle Evolution 被引量:3
16
作者 余淳梅 郑建平 Griffin WL 《Journal of China University of Geosciences》 SCIE CSCD 2006年第1期25-33,共9页
The compositions of the whole rocks and trace elements of minerals in peridotites can reflect the characteristics of the lithospheric mantle. The nature and evolution of the Cenozoic lithospheric mantle beneath Hannuo... The compositions of the whole rocks and trace elements of minerals in peridotites can reflect the characteristics of the lithospheric mantle. The nature and evolution of the Cenozoic lithospheric mantle beneath Hannuoba (汉诺坝), located on the north edge of the intra-North China orogenic belt, are discussed based on the in-situ LAM-ICPMS detected trace element compositions of clinopyroxenes in the Hannuoba peridotitic xenoliths combined with detailed petrography and geochemistry studies. The Hannuoba lithospheric mantle was formed by different partial meltings of the primitive mantle. Most of the samples reflect the partial melting degree of lower than 5% with a few samples of 15%-20%. Major element compositions of the whole rocks and geochemical compositions of clinopyroxenes reveal the coexistence of both fertile and depleted mantle underneath the Hannuoba region during the Cenozoic. This was probably caused by the asthenospheric mantle replacing the aged craton mantle through erosion, intermingling and modification. Our conclusion is further supported by the existence of both carbonatitic magmatic material and silicate melt/ fluid metasomatism as magnified by the trace elements of the clinopyroxencs from the Hannuoba lithospherJc mantle. 展开更多
关键词 peridotite xenoliths LAM-ICPMS lithospheric mantle evolution HANNUOBA North China craton
下载PDF
Three Stages of Zircon Growth in Magmatic Rocks from the Pingtan Complex,Eastern China 被引量:2
17
作者 WANG Xiang W. L. GRIFFIN +1 位作者 S. Y. O'REILLY LI Wuxian 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2007年第1期68-80,共13页
Morphological and chemical studies on zircon grains from gabbro and granite of the Pingtan magmatic complex, Fujian Province, eastern China, show that there are three stages of zircon growth. The early stage of zircon... Morphological and chemical studies on zircon grains from gabbro and granite of the Pingtan magmatic complex, Fujian Province, eastern China, show that there are three stages of zircon growth. The early stage of zircon growth is characterized by colorlessness, high transparence and birefringence, low and dispersive Ipr and Ipy, weak and homogeneous BSE brightness, lower Hf content and depletion of U, Th and Y; the middle stage is characterized by abruptly increasing lpy, progressively strong and sectoral-zoning BSE brightness, higher Hf content and enrichment of U, Th and Y with Th/U 〉 1; the late stage of growth is characterized by brownish color, poor transparence, low birefringence, highest Ipr and Ipy, middle and oscillatorily-zoning BSE brightness, highest contents of Hf, U and Y with Th/U 〈 1. The stages are considered to be formed in a deep magma chamber, ascent passage and emplacement site, respectively. Due to the more or less long residual time of the magma chamber, the difference in age between the early and late stages of zircon might be great enough to be distinguished, which can be attributed to tectonic constraint for the magnlatism. 展开更多
关键词 ZIRCON three stages of crystal growth TYPOLOGY trace element magmatic rock
下载PDF
Combined U-Pb SHRIMP and Hf isotope study of the Late Paleozoic Yaminue Complex,Rio Negro Province,Argentina:Implications for the origin and evolution of the Patagonia composite terrane 被引量:3
18
作者 Carlos J.Chernicoff Eduardo O.Zappettini +2 位作者 Joao O.S.Santos Neal J.McNaughton Elena Belousova 《Geoscience Frontiers》 SCIE CAS CSCD 2013年第1期37-56,共20页
We have carried out zircon U-Pb SHRIMP dating and Hf isotope determinations on a biotite paraschist and on a tonalitic orthogneiss of the Yaminué Complex, and re-evaluate this complex in the broader context of th... We have carried out zircon U-Pb SHRIMP dating and Hf isotope determinations on a biotite paraschist and on a tonalitic orthogneiss of the Yaminué Complex, and re-evaluate this complex in the broader context of the tectonic evolution of the Patagonia composite terrane. In the metasedimentary unit (msuYC), the youngest detrital zircon dated at 318 ± 5 Ma (Mississippian/Pennsylvanian boundary) indicates a Pennsylvanian (or younger) depositional age. The three main age populations peak at 474, 454 and 374 Ma. Preliminary Hf isotope data for two detrital zircons (447 and 655 Ma) yielded ε(Hf) values of -0.32 and 0.48, indicating that their primary sources contained small amounts of recycled crustal components (of Calymmian age; TDM 1.56 Ga). Zircons from the orthogneiss (miuYC; intrusive into msuYC) show a crystallization age of 261.3 - 2.7 Ma (Capitanian; late middle Permian) which is broadly coeval with deformation, and Neoarchean-Paleoproterozoic inheritance. Meaningful core-rim relationship between Neoarchean zircon cores and late Permian rims is well defined, indicating the occurrence of Archean crust in this sector of Patagonia. Hf TDM of Permian zircons is mainly Meso-Paleoarchean (2.97-3.35 Ga), with highly negative e(Hf) values (ca, -33). Hf TDM of inherited Neoarchean zircon cores is also Meso-Paleoarchean (3.14-3.45 Ga) but more juvenile (ε(Hf) = -0.3). Hf isotopes reinforce the presence of unexposed ancient crust in this area. Combining geological and isotope data, as well as geophysical models, we identify the Yaminué Complex within the La Esperanza-Yaminué crustal block flanked by two other, distinct crustal blocks: the Eastern block which forms part of the Patagonia terrane sensu stricto, located in the eastern Patagonian region, and the Western block forming part of the Southern Patagonia terrane. Their origins and timing of amalgamation to form the Patagonia composite terrane are also discussed. 展开更多
关键词 Yaminue Complex U-Pb SHRIMP geochronology Hf isotopes Tectonics North Patagonian Massif Argentina
下载PDF
Cold plumes trigger contamination of oceanic mantle wedges with continental crust-derived sediments:Evidence from chromitite zircon grains of eastern Cuban ophiolites 被引量:1
19
作者 J.A.Proenza J.M.González-Jiménez +10 位作者 A.Garcia-Casco E.Belousova W.L.Griffin C.Talavera Y.Rojas-Agramonte T.Aiglsperger D.Navarro-Ciurana N.Pujol-Solà F.Gervilla S.Y.O’Reilly D.E.Jacob 《Geoscience Frontiers》 SCIE CAS CSCD 2018年第6期1921-1936,共16页
The origin of zircon grains, and other exotic minerals of typical crustal origin, in mantle-hosted ophiolitic chromitites are hotly debated. We report a population of zircon grains with ages ranging from Cretaceous(99... The origin of zircon grains, and other exotic minerals of typical crustal origin, in mantle-hosted ophiolitic chromitites are hotly debated. We report a population of zircon grains with ages ranging from Cretaceous(99 Ma) to Neoarchean(2750 Ma), separated from massive chromitite bodies hosted in the mantle section of the supra-subduction(SSZ)-type Mayari-Baracoa Ophiolitic Belt in eastern Cuba. Most analyzed zircon grains(n = 20, 287 ± 3 Ma to 2750 ± 60 Ma) are older than the early Cretaceous age of the ophiolite body, show negativeε_(Hf)(t)(-26 to-0.6) and occasional inclusions of quartz, K-feldspar,biotite, and apatite that indicate derivation from a granitic continental crust. In contrast, 5 mainly rounded zircon grains(297±5 Ma to 2126±27 Ma) show positive εHf(t)(+0.7 to +13.5) and occasional apatite inclusions, suggesting their possible crystallization from melts derived from juvenile(mantle)sources. Interestingly, younger zircon grains are mainly euhedral to subhedral crystals, whereas older zircon grains are predominantly rounded grains. A comparison of the ages and Hf isotopic compositions of the zircon grains with those of nearby exposed crustal terranes suggest that chromitite zircon grains are similar to those reported from terranes of Mexico and northern South America. Hence, chromitite zircon grains are interpreted as sedimentary-derived xenocrystic grains that were delivered into the mantle wedge beneath the Greater Antilles intra-oceanic volcanic arc by metasomatic fluids/melts during subduction processes. Thus, continental crust recycling by subduction could explain all populations of old xenocrystic zircon in Cretaceous mantle-hosted chromitites from eastern Cuba ophiolite.We integrate the results of this study with petrological-thermomechanical modeling and existing geodynamic models to propose that ancient zircon xenocrysts, with a wide spectrum of ages and Hf isotopic compositions, can be transferred to the mantle wedge above subducting slabs by cold plumes. 展开更多
关键词 ZIRCON U-Pb geochronology Chromitites COLD PLUMES OPHIOLITES Cuba
下载PDF
Sulfide Aggregation in Ophiolitic Dunite Channels Explains Os-Isotope Mismatch between Oceanic Crust and Mantle
20
作者 XIONG Qing XU Yong +5 位作者 José M.GONZÁLEZ-JINÉNEZ LIU Jingao Olivier ALARD ZHENG Jian-Ping William L.GRIFFIN Suzanne Y.O’REILLY 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2020年第S01期66-66,共1页
The osmium-isotope mismatch commonly reported between mid-ocean-ridge basalts(MORBs) and residual mantle might reflect evolution of the MORB Re-Os system after extraction from the asthenosphere, or preferential contri... The osmium-isotope mismatch commonly reported between mid-ocean-ridge basalts(MORBs) and residual mantle might reflect evolution of the MORB Re-Os system after extraction from the asthenosphere, or preferential contribution of radiogenic Os components from mantle. However, in a MOR system, the role of dunite melt channels from the upper mantle and Moho transition zone in regulating isotopic systems between mantle and crust has rarely been evaluated. We report new Re-Os isotopic compositions of base-metal sulfides(BMS), chromites and dunites from dunite lenses with low spinel Cr# [Cr3+/(Cr3++Al3+) ≤ 0.66](products of interaction between MORB-like melts and upper-mantle harzburgites) from the Zedang ophiolite(South Tibet). Re-Os isotopic compositions of low-Cr# dunites from the Oman ophiolite are also shown for comparison. Mineralogical evidence suggests that the Zedang sulfides were originally precipitated as monosulfide solid solutions. The highly variable 187Os/188Os initial ratios(0.1191-0.1702) and low 187Re/188Os(<0.22) of the sulfides suggest that the chromite acted as a sink for Os-bearing sulfides, aggregating discrete Os components with heterogeneous isotopic signatures from asthenospheric or lithospheric mantle into dunite channels. The Zedang chromites and dunites show 187Os/188Os ratios similar to the primitive upper mantle(PUM), except for two dunites with sub-PUM ratios, reflecting the contribution of Os balanced by smaller volumes of Os-rich, unradiogenic sulfides(likely nucleating on Os nanoparticles) and larger volumes of Os-poor radiogenic BMS. Such isotopic heterogeneity, despite with less variation, has been observed in dunite channels from the Oman ophiolite and present-day mid-ocean ridges. Formation of dunite channels in the upper mantle thus can aggregate Os-bearing sulfides with chromite, leaving high Re/Os components into the residual melts. Once such channel systems were built up at the crust-mantle transition zone, the newly incoming MOR magmas would preferentially melt and dissolve the volumetrically abundant radiogenic BMS and retain Os-rich nanoparticles in the channels, further amplifying the Os-isotope mismatch between oceanic crust and mantle. This study sheds new light on the multistage evolution and small-scale behaviors of chalcophile and siderophile elements(e.g., Re-Os) and their isotopes(e.g., 187Re-187Os) with sulfides and chromites in a silicate-dominated melt plumbing system beneath mid-ocean ridges. 展开更多
关键词 sulfide aggregation dunite melt channels Re-Os isotopes Os-isotope mismatch of oceanic crust and mantle melt plumbing system mid-ocean ridges
下载PDF
上一页 1 2 3 下一页 到第
使用帮助 返回顶部