Zircon U-Pb ages and Hf isotopic characteristics of the Dehe biotite monzonitic gneiss pluton in the North Qinling orogen and their geological significance   总被引：1，自引：0，他引：1  

LEE Ben 《中国地球化学学报》2011,30(2):204-216

The Dehe granitic pluton intruded the Xiahe Group which is in the core complex of the North Qinling Orogenic Belt(NQOB).It shows gneissic bedding and possesses typical S-type granite minerals such as muscovite and garnet.LA-ICP-MS U-Pb isotopic dating of the Dehe granite yielded a weighted average age of 925±23 Ma which represents the emplacement age of the pluton.Most of the εHf(t) values are negative,and the two-stage model ages are consistent with the age of the Qinling Group.The isotope data show that the Dehe granite was formed in the following geological setting:in the syn-collision setting of the NQOB in the Neoproterozoic,crustal thickening induced partial melting of materials derived from the Qinling complex,and then the maga upwelled and intruded into the Xiahe Group.The formation of the Dehe S-type granite implied the occurrence of a convergent event in the QOB during the Neoproterozoic.  相似文献   

Variability of Nonionellina labradorica Dawson in Surface Sediments from Kongsfjorden, West Spitsbergen     

Suhas SHETYE  Rahul MOHAN  Sunil Kumar SHUKLA  Sudhakar MARUTHADU  Rasik RAVINDRA 《《地质学报》英文版》2011,85(3):549-558

Kongsfjorden is a fjord in Spitsbergen (Svalbard archipelago) that lies adjacent to both Arctic and Atlantic water masses and is therefore a suitable site to understand the effects of climate change on ecosystems. To decipher the effect of the lateral advection of transformed Atlantic water (TAW) within the fjord, spatial variations of foraminiferal tests, their test size variations and stable isotopic composition (δ13C and δ18O) in the surface sediments were studied. Total organic carbon and textural analyses were also carried out. The dominant benthic foraminifera included Nonionellina labradorica, Elphidium excavatum, Cassidulina reniforme, Quinqueloculina stalkeri and Islandiella islandica. Nonionellina labradorica was the predominant species in the outer fjord, whereas Elphidium excavatum and Cassidulina reniforme were dominant in the inner fjord. Total organic carbon and the test size of Nonionellina labradorica within the fjord were highly correlated (r2?=?0.97) and both showed a decreasing trend towards the inner fjord. Based on the distribution and abundance of Nonionellina labradorica as well as temperature profiles, we suggest that there was little or no major change in the lateral advection of TAW within the fjord in the immediate past.  相似文献   

Changes of Late Mesozoic Tectonic Regimes around the Ordos Basin (North China) and their Geodynamic Implications   总被引：4，自引：0，他引：4  

ZHANG Yueqiao  SHI Wei  DONG Shuwen 《《地质学报》英文版》2011,85(6):1254-1276

A synthesis is given in this paper on late Mesozoic deformation pattern in the zones around the Ordos Basin based on lithostratigraphic and structural analyses. A relative chronology of the late Mesozoic tectonic stress evolution was established from the field analyses of fault kinematics and constrained by stratigraphic contact relationships. The results show alternation of tectonic compressional and extensional regimes. The Ordos Basin and its surroundings were in weak N-S to NNE-SSW extension during the Early to Middle Jurassic, which reactivated E-W-trending basement fractures. The tectonic regime changed to a multi-directional compressional one during the Late Jurassic, which resulted in crustal shortening deformation along the marginal zones of the Ordos Basin. Then it changed to an extensional one during the Early Cretaceous, which rifted the western, northwestern and southeastern margins of the Ordos Basin. A NW-SE compression occurred during the Late Cretaceous and caused the termination of sedimentation and uplift of the Ordos Basin. This phased evolution of the late Mesozoic tectonic stress regimes and associated deformation pattern around the Ordos Basin best records the changes in regional geodynamic settings in East Asia, from the Early to Middle Jurassic post-orogenic extension following the Triassic collision between the North and South China Blocks, to the Late Jurassic multi-directional compressions produced by synchronous convergence of the three plates (the Siberian Plate to the north, Paleo-Pacific Plate to the east and Lhasa Block to the west) towards the East Asian continent. Early Cretaceous extension might be the response to collapse and lithospheric thinning of the North China Craton.  相似文献   

北太平洋涡旋振荡研究进展   总被引：1，自引：0，他引：1  

张立凤  吕庆平  张永垂 《地球科学进展》2011,26(11):1143-1149

从观测事实和动力机制两方面,对近年发现的新的气候模态——北太平洋涡旋振荡（NPGO）的研究成果进行系统总结。NPGO的空间结构表现为北太平洋上海表高度异常（SSHA）的正负中心呈南北偶极子分布,当NPGO位于正位相时,南北涡流都加强,这种加强是由风应力旋度及风生涌流所驱动的。关于NPGO的机制研究发现,NPGO是中纬太...  相似文献   

Comparison of Results of Recent Seismic Profiles with Tectonic Models of the North China Craton     

Timothy M Kusky 《中国地质大学学报(英文版)》2011,(2)

The geometry and timing of amalgamation of the North China craton(NCC) have been controversial,with three main models with significantly different interpretations of regional structure,geochronology,and geological relationships.The model of Zhao G C et al.suggests that the eastern and western blocks of the NCC formed separately in the Archean,and an active margin was developed on the eastern block between 2.5 and 1.85 Ga,when the two blocks collided above an east dipping subduc-tion zone.The model of Kusky ...  相似文献   

苏北盆地溱潼凹陷殷庄—台兴区块阜宁组三段沉积特征及砂体展布          下载免费PDF全文

吴展 《江苏地质》2011,35(1):28-32

苏北盆地溱潼凹陷殷庄—台兴区块阜宁组三段自上而下分为Ⅰ、Ⅱ、Ⅲ、Ⅳ4个砂组,沉积相组合为三角洲前缘相——包括前缘近端坝、远端坝、分流间湾相砂体夹浅湖—半深湖相泥岩互层。各砂组在分布上具有不同的形态。广山、殷庄、台兴、戴南地区发育的三角洲前缘近端坝和远端坝为有利储集相带。  相似文献   

华北油田留58潜山雾迷山组储层非均质性研究     

李宇  胡明  邓绍强  陈海华  慈建发  代华明 《四川地质学报》2011,(3):293-296

留58潜山蓟县系雾迷山组油藏为块状裂缝性灰岩油藏,储层空间类型包括了原生孔隙,溶蚀孔隙,以及裂缝等类型.潜山储层物性的分布特点表现为纵向上的分层发育和横向上的分带发育.综合本区测井解释及岩心观察认为,影响潜山储层发育的因素包括储层岩性,纵向上不同储层段与内幕隔层的配置关系,以及平面上储层发育带是否处于潜山构造顶部或断层...  相似文献   

北武夷蔡家坪铅锌矿床硫化物特征、矿床成因类型及成矿时代   总被引：1，自引：0，他引：1       下载免费PDF全文

代堰锫  余心起  吴淦国  李春麟  邱骏挺  张家菁  罗平 《地学前缘》2011,18(2):321-338

北武夷蔡家坪矿床是近年来新发现的一个中型铅锌矿床.矿床赋矿围岩为侏罗系水北组(J1s)、漳平组(J2z)砂岩,铅锌矿体多产在断裂旁侧破碎带及流纹斑岩与砂岩接触带.在野外调查基础上,通过显微镜下观察及电子探针分析,对矿区主要金属硫化物进行了细致研究.初步将成矿过程划分为沉积成矿期、岩浆热液期与表生期,其中岩浆热液期包括中...  相似文献   

从阿巴拉契亚-阿钦塔造山带看中国北方大陆南缘古生代的油气前景          下载免费PDF全文

梁传茂 《地学前缘》2011,18(4):193-200

阿巴拉契亚-阿钦塔造山带是北美乃至世界著名的大陆边缘挤压碰撞推覆造山带,是地质学研究的经典地区之一,也是许多经典地学理论和概念的发源地.其中,对地质学影响最大的当属地槽学说.继20世纪60年代由深海钻探带来地学革命之后,由COCORP实施的地震反射剖面和深钻揭示了该造山带的巨大推覆构造.人们惊奇地发现,在巨大推覆体之下...  相似文献   

内蒙古盘羊山逆冲推覆构造系统的组合特征     

谢静博  王风华  尚婷  李剑锋  马凯波 《华北地质》2011,34(1):23-28

通过1/25万四子王旗幅的野外地质填图,在蒙古寺-盘羊山-乌兰合雅一线存在古生代末大型逆冲推覆构造系统,新太古代色尔腾山岩群和新太古代花岗岩自北向南被逆冲推覆于震旦系什那干组灰岩和古生代碎屑岩之上,并形成大小规模的飞来峰和构造窗。整个推覆系统由顶板逆冲断层与底板逆冲断层及夹于其中的一套叠瓦式逆冲断层和断层夹块组合而成,构成典型的双重逆冲推覆构造系统(Duplex)。该逆冲推覆构造总体逆冲方向指向南南西向,形成时代为二叠纪末,估算推覆距离应大于7.1 km。此逆冲推覆构造与华北板块与西伯利亚板块在二叠纪末陆内碰撞造山有关,是华北板块北缘造山带的重要组成部分。  相似文献