华南西部地区晚中生代与W-Sn矿有关花岗岩的年代学格架及地质意义   总被引：10，自引：3，他引：7  

程彦博  童祥  武俊德  莫国培 《岩石学报》2010,26(3):809-818

华南西部地区是我国重要的大型-超大型锡多金属矿床分布区。本文根据近年来新获得的花岗岩LA-ICP-MS锆石U-Pb数据,结合近几年以来新报道的高精度成岩成矿年代学资料和地球动力学研究进展,总结发现华南西部地区中生代岩浆-成矿作用的时代主要集中在晚白垩世(76～98Ma)。通过分别总结华南东、西部地区晚白垩岩浆作用及相应的成矿作用的特征,发现华南东、西部的成岩成矿作用特征表现出明显的差异,但是这两地内部各自却表现出高度的一致性;且东部地区明显要比西部地区更为复杂,但二者之间的共同点在于该时期均处于岩石圈伸展的环境和壳幔间的相互作用明显。晚白垩世华南西部地区主要受控于华南陆块陆内背景下岩石圈伸展而导致的岩浆-成矿作用这一因素,而东部地区除此之外还受到太平洋古板块北北东向走滑带来的影响。  相似文献   

吉林珲春三叠纪高镁闪长岩的发现及地质意义   总被引：5，自引：3，他引：2  

付长亮  孙德有  张兴洲  魏红艳  苟军 《岩石学报》2010,26(4):1089-1102

吉林珲春地区首次发现的高镁闪长岩对于讨论东北地区岩石圈演化历史具有重要意义。该类岩石的锆石LAICPMSU-Pb年龄为241～240Ma,SiO_2和MgO的含量分别介于51.93%～55.85%和3.97%～10.38%之间,具有较高的Mg~#(0.45～0.70),属于钠质钙碱性系列。轻稀土略微富集,但稀土配分曲线近于平坦型,富集Rb,亏损Ba、Nb、Ta、P和Ti等元素。该类岩石的锆石~(176)Hf/~(177)Hf值和ε_(Hf)(t)值分别变化于0.282672～0.283085和1.78～15.95之间,显示地幔来源的特征,最小单阶段模式年龄(t_(DMI)=246Ma)与其侵入年龄(t=240～241Ma)相一致,表明该区乃至延边地区在240Ma左右的中三叠世存在一次重要的地壳增生事件。Sr/Y(3.19～12.48)-Y(19.3×10~(-6)～81.1×10~(-6))和(La/Yb)_N(1.00～3.51)-Yb_N(4.15～14.62)判别图解显示其形成可能与赞岐岩有相似的岩浆过程,即形成于消减带之上的地幔楔环境,由地幔橄榄岩与消减洋壳板片部分熔融产生的富Si质熔体平衡反应形成。综合研究表明,延边地区早三叠世之前为活动陆缘环境,古亚洲洋板块向华北板块之下俯冲。  相似文献   

庐-枞金属矿集区深地震反射剖面解释结果——揭露地壳精细结构,追踪成矿深部过程   总被引：18，自引：4，他引：14  

高锐  卢占武  刘金凯  匡朝阳  酆少英  李朋武  张季生  王海燕 《岩石学报》2010,26(9):2543-2552

深地震反射剖面揭示了庐枞矿集区全地壳的精细结构,在研究火山岩盆地的深部构造、探讨成矿深部过程等方面取得了新认识。从长江至大别山下,Moho由30km左右加深至33km左右,罗河矿下方Moho错断大约3km。庐枞火山岩盆地是一个沿着罗河断裂向东发育的"耳状"非对称盆地,并不存在另外一半隐伏在红层之下的盆地。罗河铁矿对应Moho错断处,处在构造的转换带上。罗河断裂之下存在近于透明的弱反射区域,可能是地幔流体和岩浆上涌、喷发的通道。郯庐断裂、罗河-缺口断裂、长江断裂是庐枞地区的三个重要断裂。郯庐断裂带为不对称花束状构造,近于直立,切穿地壳。小岭矿与龙桥矿可能产出在一个隆起的火成岩体的两翼。  相似文献   

Reworking of Earth's first crust: Constraints from Hf isotopes in Archean zircons from Mt. Narryer,Australia     

Y. Nebel-Jacobsen  C. Münker  O. Nebel  A. Gerdes  K. Mezger  D.R. Nelson 《Precambrian Research》2010

Discoveries of >4 Ga old zircon grains in the northwest Yilgarn of Western Australia led to the conclusion that evolved crust formed on the Earth within the first few 100 Ma after accretion. Little is known, however, about the fate of the first crust that shaped early Earth's surface. Here we report combined solution and laser-ablation Lu–Hf–U–Pb isotope analyses of early Archean and Hadean detrital zircon grains from different rocks of the Narryer Gneiss Complex (NGC), Yilgarn Craton, Western Australia. The zircons show two distinct groups with separate evolutionary trends in their Hf isotopes. The majority of the zircon grains point to separation from a depleted mantle reservoir at ∼3.8–3.9 Ga. The second Hf isotope trend implies reworking of older Hadean zircon grains. The major trend starting at 3.8–3.9 Ga defined by the Hf isotopes corresponds to a Lu/Hf that is characteristic for felsic crust and consequently, the primary sources for these zircons presumably had a chemical composition characteristic of continental crust. Reworked Hadean crust appears to have evolved with a similar low Lu/Hf, such that the early crust was probably evolved with respect to Lu–Hf distributions. The co-variation of Hf isotopes vs. age in zircon grains from Mt. Narryer and Jack Hills zircon grains implies a similar crustal source for both sediments in a single, major crustal domain. Age spectra and associated Hf isotopes in the zircon grains strongly argue for ongoing magmatic reworking over hundreds of millions of years of the felsic crustal domain in which the zircon grains formed. Late-stage metamorphic zircon grains from the Meeberrie Gneiss unit yield a mean U–Pb age of 3294.5 ± 3.2 Ma with initial Hf isotopes that correspond to the evolutionary trend defined by older NGC zircon grains and overlap with other detrital zircon grains, proving their genetic relationship. This ‘Meeberrie event’ is interpret here as the last reworking event in the precursor domain before final deposition. The continuous magmatic activity in one crustal domain during the Archean is recorded by the U–Pb ages and Hf isotope systematics of zircon grains and implies reworking of existing crust. We suspect that the most likely driving force for such reworking of crustal material is ongoing crustal collision and subduction. A comparison of Hf isotope signatures of zircon grains from other Archean terranes shows that similar trends are recognised within all sampled Archean domains. This implies either a global trend in crustal growth and reworking, or a genetic connection of Archean terranes in close paleo-proximity to each other. Notably, the Archean Acasta gneiss (Canada) shows a similar reworking patterns to the Yilgarn Craton of Hadean samples implying either a common Hadean source or amalgamation at the Hadean–Archean transition.  相似文献   

A tentative 2D thermal model of central India across the Narmada-Son Lineament (NSL)   总被引：1，自引：0，他引：1  

S.N. Rai  S. Thiagarajan 《Journal of Asian Earth Sciences》2006,28(4-6):363-371

This work deals with 2D thermal modeling in order to delineate the crustal thermal structure of central India along two Deep Seismic Sounding (DSS) profiles, namely Khajuriakalan–Pulgaon and Ujjan–Mahan, traversing the Narmada-Son-Lineament (NSL) in an almost north–south direction. Knowledge of the crustal structure and P-wave velocity distribution up to the Moho, obtained from DSS studies, has been used for the development of the thermal model. Numerical results reveal that the Moho temperature in this region of central India varies between 500 and 580 °C. The estimated heat flow density value is found to vary between 46 and 49 mW/m². The Curie depth varies between 40 and 42 km and is in close agreement with the Curie depth (40±4 km) estimated from the analysis of MAGSAT data. Based on the present work and previous work, it is suggested that the major part of peninsular India consisting of the Wardha–Pranhita Godavari graben/basin, Bastar craton and the adjoining region of the Narmada Son Lineament between profiles I and III towards the north and northwest of the Bastar craton are characterized with a similar mantle heat flow density value equal to 23 mW/m². Variation in surface heat flow density values in these regions are caused by variation in the radioactive heat production and fluid circulation in the upper crustal layer.  相似文献   

基于Java3D的三维景观网络发布   总被引：3，自引：2，他引：1  

田茂义  张燕  卢秀山  徐文锦  刘峰 《测绘科学》2006,31(4):115-116,125

论文提出了基于J2EE三层体系构架,浏览器/服务器(B/S)结构模式的三维景观W eb发布系统模型。该模型综合利用了App le、tJSP、Servle、tJava3D、BC4 J技术,其基本思路是:利用Java3D三维图形库开发植入JSP的App let插件用于三维景观的显示与交互,通过BC4 J、代理服务器技术实现App let与O rac le数据库服务器之间的数据通讯。实验结果证明了这种结构模型具有一定的优越性。  相似文献   

空间地理信息网络服务集成框架初探   总被引：2，自引：1，他引：1  

黄海峰  夏斌  黎华  熊永柱 《测绘科学》2006,31(4):112-114

本文在分析了W eb服务体系结构和OGC相关规范的基础上,提出了空间地理信息网络服务集成框架。框架由空间地理信息服务(提供者)、空间地理信息服务注册处(中介)和客户端(请求者)组成。并利用ESR I的空间地理信息网络服务雏形-ArcW eb,成功构建了一个简单的G IS应用。最后提出了要真正实现成熟的标准框架,还需要解决服务的标准化、空间数据传输以及地图数据显示等问题。  相似文献   

东北非地层区划及其地层格架与对比     

王成刚  向文帅  李福林  王建雄  吴发富  李勇 《地质通报》2022,(1):99-118

东非造山带作为全球出露较完整的前寒武系造山带之一,蕴藏了丰富的矿产资源.在查阅苏丹、厄立特里亚、埃塞俄比亚基础地质资料的基础上,将研究区划分为撒哈拉、东非和东冈瓦纳3个地层大区,进一步划分出Nukheila、Zalingei、Bayuda、Muglad-Kosti、努比亚、莫桑比克、East Ogaden和West O...  相似文献   

“数字北海”地理空间框架数据的组织方法     

覃婕  王成 《地理空间信息》2012,(3):13-16

针对目前"数字北海"地理空间框架建设中存在的问题,提出了地理空间框架混合数据库数据组织方法,给出了"数字北海"地理空间框架数据的制作流程,对基础空间数据和专题数据进行统一组织,并实现了这些数据的关联一体化管理。  相似文献   

形变台网数据中心数据库系统   总被引：1，自引：1，他引：0  

陈志遥  李正媛  陈鹏  林穗平 《大地测量与地球动力学》2003,23(1):78-80

介绍了形变台网数据中心数据库的系统功能，形变台站基础资料和基本信息库、观测值数据库、震例图形库等子库系统的结构设计以及目前的运行情况。  相似文献