四川北部米仓山地区下三叠统内部不整合面的发现及其意义   总被引：5，自引：4，他引：1  

沈中延  肖安成  王亮  郭璟  魏国齐  张林 《岩石学报》2010,26(4):1313-1321

前人认为四川北部米仓山地区下三叠统内部各组地层之间是整合接触,然而通过构造和沉积学的研究发现下三叠统内部(奥伦尼阶)存在一个区域不整合面。在沉积上表现为环米仓山地区广泛发育的陆相和海相碎屑岩,与下伏地层呈不整合接触。地震剖面上表现为不整合面上下的变形特征不一致、不整合面下部地层被削截、古构造的存在等等,通过对古褶皱和古断裂的平面投影,发现古构造走向为东-西向,与勉略构造带走向一致。综合区域大地构造历史,笔者认为在早三叠世奥伦尼期(约249.7～245.0Ma)南秦岭造山带和上扬子地块就已经发生碰撞,碰撞引起了米仓山地区强烈的构造变形,形成这一区域不整合面。该碰撞时间不一定是南秦岭造山带和上扬子地块在此处的初始碰撞时间。  相似文献   

Tectonic Evolution of the Northern Continental Margin of North China Platform in Middle Proterozoic     

Xu Zhongyuan  Liu Zhenghong 《世界地质(英文版)》2000,3(1)

An orogenic belt developed in late middle Proterozoic in the northern margin of North China Plate extends from Inner Mongolia to Western Liaoning Province and Eastern Jilin Province. It is over 2000km long. The orogenic belt was formed by collision between North China Platform and Siberia Platform during the Rodinian Super- Continent period. From sedimentary formation, magmatic activity and crustal tectonic deformation, it is suggested that along the tectonic belt the paleocontinental margin experienced four stages of tectonic evolution in middle Proterozoic, they are: continental margin rift,passive continental margin, active continental margin and collisional orogenic stages.  相似文献   

云南中甸热林岩体的成矿作用     

伍建兢  杨丽梅  吴俊 《云南地质》2011,30(2):216-219

热林矿区的热林复式花岗岩体,从早至晚、边部到中部,分出4个侵入体组成的同源岩浆细粒-中粒-斑状结构演化系列。成矿作用有差异,从而形成各具特色的矿床。  相似文献   

A Paleozoic subduction complex in Korea: SHRIMP zircon U–Pb ages and tectonic implications     

Sung Won Kim  Sanghoon Kwon  M. Santosh  Ian S. Williams  Keewook Yi 《Gondwana Research》2011,20(4):890-903

The Wolhyeonri complex in the southwestern margin of the Korean Peninsula is divided into three lithotectonic units: Late Paleozoic Zone I to the west, Middle Paleozoic Zone II in the middle and Early Paleozoic Zone III to the east. Zones II and III display characteristics of continental arc magmatic sequence. Zone II is dominated by mafic metavolcanics, whereas zone III is characterized by the presence of dismembered serpentinite bodies including chaotic mélange. These zones are proposed to have been formed in a convergent margin setting associated with subduction. Here we present zircon SHRIMP U–Pb ages from the various units within the Wolhyeonri complex which reveal the Paleozoic tectonic history of the region. The Late Carboniferous ages obtained from the main shear zone between the Wolhyeonri complex and the Paleoproterozoic Gyeonggi massif are thought to mark the timing of continental arc magmatism associated with the subduction process. In contrast, Zone I with Neoproterozoic arc magmatic remnants might indicate deposition in a forearc basin. The Wolhyeonri complex also preserves strong imprints of the Triassic collisional event, including the presence of Middle Triassic high-pressure metabasites and eclogites near the eastern boundary of the Zone III. These range of radiogenic ages derived from the Wolhyeonri complex correlate well with subduction and accretion history between the North and South China cratons. Similar geochronological features have also been indentified from the Qinling, Tongbai–Xinxian, and northern Dabie areas in east-central China. The existence of Paleozoic coeval subduction in East Asia prior to the Triassic collision is broadly consistent with a regional tectonic linkage to Gondwana.  相似文献   

铷频标物理部分的改进与长期稳定度的测量     

刘淑琴  董太乾 《时间频率学报》1996,19(1):38-41

为了提高铷频标长稳，消除老化漂移，我们用不同同位素的特殊比例、几种不同缓冲气体的特殊比例、化学性能稳定的特殊玻璃来充制铷吸收泡．通过较长时问的观测，改进后的铷频标长稳和短稳兼而优之，物理部分温度系数指标提高一个数量级，基本消除了了铷频标的老化漂移．  相似文献   

Granite-types in the Hohe Tauern (Eastern Alps,Austria) — Some aspects on their correlation to Variscan plate tectonic processes     

F. Finger  H.P. Steyrer 《Geodinamica Acta》2013,26(2):75-87

Abstract

The Zentralgneise in the Hohe Tauern (Penninic Zone, Eastern Alps, Austria) can be interpreted essentially as metamorphosed Late Paleozoic orogenic plutonites with original compositions mainly of granites, granodiorites and tonalites, rarely also of diorites, quartzdiorites, quartzmonzodiorites, quartzmonzonites and quartzsyenites. Most of the granitoids show attributes of “Cordilleran I-type granites” respectively “volcanic arc granites”.

Due to their similarity to subduction derived granitoids from present day active continental margins in the Circum-Pacific area, it is assumed, that the I-type granitoids of the Hohe Tauern reflect the influence of a Variscan destructive plate boundary.

Among the Zentralgneise also minor amounts of granites with features towards the S-type occur, which are more likely related to collision than to subduction.

Seen as a whole, the Late Paleozoic plutonism played probably part in a compressional continental margin and originated during a Variscan subduction-collision scenario, that occurred along the southern flank of Central European Hercynian fold belt.  相似文献   

Genesis of the Ibero-Armorican arc     

A. Ribeiro  R. Dias  J. BrandÃo Silva 《Geodinamica Acta》2013,26(4):173-184

Abstract

The Ibero-Armorican arc is continuous between Iberia and Armorica; its curvature increased with time due to subduction followed by continental collision; indentation produced left lateral transpression in Iberia and right-lateral transpression in Armorica. It is argued that whereas the antithetic shear is predominant in Iberia, in Armorica a synthetic shear prevailed because the identer rotated anticlockwise between the opposed forelands of the Variscan Fold Belt. It is proposed that the major Rheic ocean, closed by subduction towards the inner part of the arc, solving the space problem of centripetal vergences.  相似文献   

Hydrogen collisions in planetary atmospheres, ionospheres, and magnetospheres     

David L. Huestis 《Planetary and Space Science》2008,56(13):1733-1743

Hydrogen is the most abundant element in the universe. Molecular hydrogen is the dominant chemical species in the atmospheres of the giant planets. Because of their low masses, neutral and ionized hydrogen atoms are the dominant species in the high atmospheres of many planets. Finally, protons are the principal heavy component of the solar wind.Here we present a critical evaluation of the current state of understanding of the chemical reaction rates and collision cross sections for several important hydrogen collision processes in planetary atmospheres, ionospheres, and magnetospheres. Accurate ab initio quantum theory will play an important role. The collision processes are grouped as follows:

(a)

H⁺+H charge transfer,

(b)

H⁺+H₂(v) charge transfer and vibrational relaxation, and

(c)

H₂(v,J)+H₂ vibrational, rotational, and ortho-para relaxation.

In each case we provide explicit representations as tabulations or compact formulas. Particularly important conclusions are that H⁺+H₂(v) collisions are more likely to result in vibrational relaxation than charge transfer and H₂ ortho-para conversion is at least an order-of-magnitude faster than previously assumed.  相似文献   

Fluid–particle interaction in turbulent open channel flow with fully-resolved mobile beds     

《Advances in water resources》2014

The paper presents Direct Numerical Simulations of an open channel flow laden with spherical particles at a bulk Reynolds number of 2941. The transport of thousands of mobile particles is simulated propagating over a rough bed which consists of immobile particles of the same size in hexagonal ordering. An Immersed Boundary Method is used for the numerical representation of the particles. With 22 points per diameter even the viscous scales of the flow are resolved at this Reynolds number. The reference run contains just as many fixed as mobile particles with a relative density slightly above the nominal threshold of incipient motion. Further runs were conducted with decreased mass loading and decreased Shields number together with a simulation containing only immobile particles. The variation of the parameters defining the mobile sediment yields a strong modification of particle–fluid as well as particle–particle interactions yielding different structures in space and time. This is assessed by means of appropriate statistical quantities addressing the continuous and the disperse phase. The results are in qualitative agreement with experimental observations at higher Reynolds number.  相似文献   

佳木斯地块与松嫩地块俯冲碰撞的深反射地震剖面证据   总被引：6，自引：2，他引：4       下载免费PDF全文

张兴洲  曾振  高锐  侯贺晟  郭冶  蒲建彬  付秋林 《地球物理学报》2015,58(12):4415-4424

佳木斯地块和松嫩地块是东北地区两个十分重要的地质构造单元,由于二者之间发育一套含有蓝片岩的俯冲增生杂岩-黑龙江杂岩(原称黑龙江群),其地质构造意义长期为人们所关注.巴彦—桦南深反射地震剖面揭示,佳木斯地块与松嫩地块之间存在明显向西俯冲的深反射信息,以壳内和幔内向西倾伏的楔状反射区为特征.壳内楔状反射区东与浅表层出露的黑龙江杂岩相连,向西倾伏延深至莫霍面,是俯冲增生杂岩在地壳深部的反映;幔内楔状反射区东起小兴安岭之下的莫霍面,向西倾伏延深至松辽盆地东缘,尖灭深度约78km,与多种方法得出的该区现今的岩石圈厚度(75~80km)基本一致.这一证据充分说明佳木斯地块的岩石圈地幔向西俯冲到松嫩地块岩石圈地幔之下.  相似文献