Micromorphological-investigation on the Earth's Critical Zone     

Ahmet Ruhi Mermut 《山地科学学报》2009,(2):I0002-I0002

Soils, the Earth＇s Critical Zone, play a vital and fundamental role in the Earth＇s terrain eco- environment system and human life. Although the concepts of soil/quality and sustainable development have been introduced for decades, we are still failing to understand how well soils function and they need tobe cared and protected. We have been increasingly witnessing and becoming the victim of shrinking forests,  相似文献   

Single Zircon LA-ICP-MS U-Pb Dating of the Guandimiao and Wawutang Granitic Plutons in Hunan, South China and Its Petrogenetic Significance   总被引：1，自引：0，他引：1  

CHEN Weifeng  CHEN Peirong  ZHOU Xinmin  HUANG Hongye  DING Xing  SUN Tao The Key Laboratory for Mineral Deposits Research  Department of Earth Sciences  Nanjing University  Nanjing  Jiangsu No. Research Institute  CNNC  Changsh  Hunan 《《地质学报》英文版》2007,81(1):81-89

1 Introduction The South China Block (SCB), located between the Qinling-Dabie and Songma Indosinian sutures, experienced successively two important tectonic movements during the Mesozoic, i.e. the Indosinian movement (early Mesozoic) and the Yanshanian movement (late Mesozoic). Therefore, the generally accepted viewpoint is that the key geological problems during the Mesozoic are essentially the dynamics and material expression of these two tectonic movements in South China (Chen et al.…  相似文献   

Chronology and Geochemistry of Volcanic Rocks in the Cretaceous Suifenhe Formation in Eastern Heilongjiang, China   总被引：3，自引：0，他引：3  

JI Weiqiang  XU Wenliang  YANG Debin  PEI Fuping  JIN Ke  LIU Xiaoming College of Earth Sciences  Jilin University  Changchun  Jilin Bureau of Land  Mineral Resources of Jilin Province  Changchun  Jilin The State Key Laboratory of Continental Dynamics  Northwest University  Xi ''an  Shaanxi 《《地质学报》英文版》2007,81(2):266-277

Zircon U-Pb ages and geochemical data of volcanic rocks in the Suifenhe Formation in eastern Heilongjiang Province are reported, and their petrogenesis is discussed in this paper. The Suifenhe Formation mainly consists of basalt, andesite, and dacite. Zircon from andesite and dacite are euhedral in shape and show typical oscillatory zoning with high Th/U ratios (0.18-0.57), implying its magmatic origin. Zircon U-Pb dating results by laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) indicate that the 206Pb/238U ages of zircons from andesite range within 105-106 Ma, yielding a weighted mean age of 105.5±0.8 Ma (n=14), and that 206Pb/238U ages of zircons from dacite are between 90-96 Ma, yielding a weighted mean age of 93.2±1.3 Ma (n =13). The volcanic rocks from the Suifenhe Formation are subalkaline series and show a calc-alkaline evolutionary trend with SiO2 content of 47.69%-65.47%, MgO contents of 1.42%-6.80% (Mg#= 45-53), and Na2O/K2O ratios of 1.83-3.63. They are characterized by enrichment in large ion lithophile elements (LILE) and light-rare-earth elements (LREE), depletion in heavy rare earth elements (HREE) and high field strength elements (HFSE) (e.g., Nb, Ta, Ti), and low initial 87Sr/86Sr ratios (0.7041-0.7057) and positiveεNd(t) values (039-4.08), implying that they could be derived from a depleted magma source. Taken together, these results suggest that the primary magma of the volcanic rocks might originate from partial melting of the mantle wedge metasomatized by fluids derived from subducted slab under a tectonic setting of active continental margin.  相似文献   

Review of Global Ocean Intermediate Water Masses: 1.Part A, the Neutral Density Surface (the ‘McDougall Surface’) as a Study Frame for Water-Mass Analysis     

Yuzhu You )  )  * ) The University of Sydney Institute of Marine Science 《中国海洋大学学报(英文版)》2006,(3)

1Preface Todescribeoceanicintermediatewatermasses,itis necessarytohaveawell definedstudyframeorsurfacebecauseofthefluctuationnatureofintermediatewa ters.Itiswellunderstoodthatoceanicwater mass mixingdoesnotalignwitheitheraconstantgeopoten tialdepthorapropertysurfacesuchastemperature,salinity,pressureanddensitysurfacesbutfollowsa neutraldensitysurface.Thisisbecauseawaterparcelmovesasmalldistanceisentropicallyandadiabaticallyontheneutraldensitysurfacewithoutdoingworka gainstabuoyantrestoringforc…  相似文献   

蛇绿岩建造非金属矿床成矿系列初步探讨     

鱼海麟 《青海国土经略》1995,(2)

我国蛇绿岩分布广泛。蛇绿岩中有着成因上和时空上紧密联系的一系列非金属矿床,它们构成了蛇绿岩建造非金属矿床成矿系列。这一成矿系列中的主要非金属矿有橄榄岩、玄武岩、蛇纹岩、石棉、滑石、玉石类等等,主要的成矿作用有岩浆作用、接触变质作用、交代蚀变作用等。其成矿作用和矿床分布模式有明显规律,这些规律对于地质勘查、资源开发等都具有重要的意义。  相似文献   

辽宁西部八家子多金属矿田控矿构造型式     

陈荣度  苏传玉 《国土资源》1991,(4)

本文分析了八家子多金属矿田的地质构造特征,提出该区的构造型式为一个滑脱—逆冲推覆构造。它是在北西问南东方向的侧向挤压作用下,由八家子附近的中上元古界与古生界地质块体,沿着与基底花岗岩的界面自北西向南东滑移造成的。主要表现特征是:在前缘形成了呈铲式的收缩型滑脱断层、逆冲断层等挤压性构造,在后缘则出现张裂带并陷落成盆地,两侧发育具有转换断层性质的走滑断层。逆冲断层及边界走精断层是区内主要控矿构造。八家子滑脱—逆冲推覆构造的主要活动时期为三叠纪晚期,结束于早侏罗世。  相似文献   

太阳物理学中的分形和混沌   总被引：1，自引：0，他引：1  

环遵祥  吴铭蟾 《天文学进展》1996,14(4):286-296

对非线性科学的两个重要分支；分形和混沌在太阳物理学中的应用情况作了综述信要内容包括；太阳活动混沌性的揭示；对太阳活动混沌性的可能解释－太阳非线性发电机理论；一些太阳现象的分形描述；耀斑的自组织临界行为研究，最后给出了作者对这一领域工作前景的展望。  相似文献   

有关内蒙古地质构造的一线之见——江苏响水至内蒙古满都拉地学断面北段研究报道之一   总被引：5，自引：0，他引：5       下载免费PDF全文

马杏垣  王楫  李双庆  刘德简  白云虹  周春平  黄国华 《地震地质》1988,10(4):45

本文概述了江苏响水至内蒙古满都拉地学断面北段——包头至满都拉的地质观察结果。内容包括从太古宙乌拉山群到第四系、基底构造到新构造特征的七个方面。重点论述了渣尔泰群和白云鄂博群的构造性质,它们约在14亿年前才褶皱回返,代表了华北地台基底固结最迟的地段。造成这一事件的构造运动,拟称为色尔腾运动。此外,还讨论了华北地台北侧陆缘区加里东期和华力西期的构造  相似文献   

Combining satellite and seismic images to analyse the shallow structure of the Dead Sea Transform near the DESERT transect     

D. Kesten  M. Weber  Ch. Haberland  Ch. Janssen  A. Agnon  Y. Bartov  I. Rabba  The DESERT Group 《International Journal of Earth Sciences》2008,97(1):153-169

The left-lateral Dead Sea Transform (DST) in the Middle East is one of the largest continental strike-slip faults of the world. The southern segment of the DST in the Arava/Araba Valley between the Dead Sea and the Red Sea, called Arava/Araba Fault (AF), has been studied in detail in the multidisciplinary DESERT (DEad SEa Rift Transect) project. Based on these results, here, the interpretations of multi-spectral (ASTER) satellite images and seismic reflection studies have been combined to analyse geologic structures. Whereas satellite images reveal neotectonic activity in shallow young sediments, reflection seismic image deep faults that are possibly inactive at present. The combination of the two methods allows putting some age constraint on the activity of individual fault strands. Although the AF is clearly the main active fault segment of the southern DST, we propose that it has accommodated only a limited (up to 60 km) part of the overall 105 km of sinistral plate motion since Miocene times. There is evidence for sinistral displacement along other faults, based on geological studies, including satellite image interpretation. Furthermore, a subsurface fault is revealed ≈4 km west of the AF on two ≈E–W running seismic reflection profiles. Whereas these seismic data show a flower structure typical for strike-slip faults, on the satellite image this fault is not expressed in the post-Miocene sediments, implying that it has been inactive for the last few million years. About 1 km to the east of the AF another, now buried fault, was detected in seismic, magnetotelluric and gravity studies of DESERT. Taking together various evidences, we suggest that at the beginning of transform motion deformation occurred in a rather wide belt, possibly with the reactivation of older ≈N–S striking structures. Later, deformation became concentrated in the region of today’s Arava Valley. Till ≈5 Ma ago there might have been other, now inactive fault traces in the vicinity of the present day AF that took up lateral motion. Together with a rearrangement of plates ≈5 Ma ago, the main fault trace shifted then to the position of today’s AF.  相似文献   

中国地震局代表团访问智利     

中国地震局赴智利代表团 《国际地震动态》2001,(6):15-16

应智利国家科学技术委员会 (CONICYT)邀请 ,以中国地震局刘玉辰副局长为团长的中国地震局代表团一行 5人 ,于 2 0 0 1年 3月 12～ 19日对智利进行了访问。智利是一个地震多发国家 ,2 0世纪在该国曾发生过一次 8.9级巨大地震 ,这是人类历史上迄今为止记录到的最大地震。智利地域狭长 ,地震多发生在北部和中部地区。目前 ,智利全国共有 5 0多个地震台 ,使用的绝大部分是短周期、单分向地震计 ,仅有 3个宽频带数字地震台装有 STS-2型地震计。其中 13个台采用无线电短波进行实时传输。智利大学等已经与法国、美国开展了合作研究 ,其中与美国…  相似文献