上扬子地壳区域性地层岩石物性力学参数与滑动层位关系研究   总被引：5，自引：2，他引：5       下载免费PDF全文

孙岩  刘德良  朱文斌  郭继春  李本亮  郭建  王锋  赵忠岩 《地质科学》2005,40(4):532-538

在中下扬子地区地壳区域性滑动层位岩石物性力学参数研究的基础上,对上扬子地区地壳的相应岩层进行了系统的定量测试。其滑动层位各种参量在塑性、韧性和粘性上所表现出特征的规律,在我国南方型数字地层中,具有一定的普遍性和可比性。同时,也揭示了地壳的构造分层性,并可作为上扬子板块浅层地质—地球物理特征分析的重要依据和建库信息。  相似文献   

6: Classification of VMS deposits: Lessons from the South Uralides     

Richard Herrington  Valeriy Maslennikov  Victor Zaykov  Igor Seravkin  Alexander Kosarev  Bernd Buschmann  Jean-Jacques Orgeval  Nicola Holland  Svetlana Tesalina  Paolo Nimis  Robin Armstrong 《Ore Geology Reviews》2005,27(1-4):203

VMS deposits of the South Urals developed within the evolving Urals palaeo-ocean between Silurian and Late Devonian times. Arc-continent collision between Baltica and the Magnitogorsk Zone (arc) in the south-western Urals effectively terminated submarine volcanism in the Magnitogorsk Zone with which the bulk of the VMS deposits are associated. The majority of the Urals VMS deposits formed within volcanic-dominated sequences in deep seawater settings. Preservation of macro and micro vent fauna in the sulphide bodies is both testament to the seafloor setting for much of the sulphides but also the exceptional degree of preservation and lack of metamorphic overprint of the deposits and host rocks. The deposits in the Urals have previously been classified in terms of tectonic setting, host rock associations and metal ratios in line with recent tectono-stratigraphic classifications. In addition to these broad classes, it is clear that in a number of the Urals settings, an evolution of the host volcanic stratigraphy is accompanied by an associated change in the metal ratios of the VMS deposits, a situation previously discussed, for example, in the Noranda district of Canada.Two key structural settings are implicated in the South Urals. The first is seen in a preserved marginal allochthon west of the Main Urals Fault where early arc tholeiites host Cu–Zn mineralization in deposits including Yaman Kasy, which is host to the oldest macro vent fauna assembly known to science. The second tectonic setting for the South Urals VMS is the Magnitogorsk arc where study has highlighted the presence of a preserved early forearc assemblage, arc tholeiite to calc-alkaline sequences and rifted arc bimodal tholeiite sequences. The boninitc rocks of the forearc host Cu–(Zn) and Cu–Co VMS deposits, the latter hosted in fragments within the Main Urals Fault Zone (MUFZ) which marks the line of arc-continent collision in Late Devonian times. The arc tholeiites host Cu–Zn deposits with an evolution to more calc-alkaline felsic volcanic sequences matched with a change to Zn–Pb–Cu polymetallic deposits, often gold-rich. Large rifts in the arc sequence are filled by thick bimodal tholeiite sequences, themselves often showing an evolution to a more calc-alkaline nature. These thick bimodal sequences are host to the largest of the Cu–Zn VMS deposits.The exceptional degree of preservation in the Urals has permitted the identification of early seafloor clastic and hydrolytic modification (here termed halmyrolysis sensu lato) to the sulphide assemblages prior to diagenesis and this results in large-scale modification to the primary VMS body, resulting in distinctive morphological and mineralogical sub-types of sulphide body superimposed upon the tectonic association classification.It is proposed that a better classification of seafloor VMS systems is thus achievable using a three stage classification based on (a) tectonic (hence bulk volcanic chemistry) association, (b) local volcanic chemical evolution within a single edifice and (c) seafloor reworking and halmyrolysis.  相似文献   

Probabilistic landslide susceptibility mapping in the Lai Chau province of Vietnam: focus on the relationship between tectonic fractures and landslides   总被引：4，自引：0，他引：4  

Saro Lee  Nguyen Tu Dan 《Environmental Geology》2005,48(6):778-787

This study evaluates the susceptibility of landslides in the Lai Chau province of Vietnam using Geographic Information System (GIS) and remote sensing data to focus on the relationship between tectonic fractures and landslides. Landslide locations were identified from aerial photographs and field surveys. Topographic, geological data and satellite images were collected, processed, and constructed into a spatial database using GIS data and image-processing techniques. A scheme of the tectonic fracturing of crust in the Lai Chau region was established. Lai Chau was identified as a region with many crustal fractures, where the grade of tectonic fracture is closely related to landslide occurrence. The influencing factors of landslide occurrence were: distance from a tectonic fracture, slope, aspect, curvature, soil, and vegetative land cover. Landslide prone areas were analyzed and mapped using the landslide occurrence factors employing the probability–frequency ratio model. The results of the analysis were verified using landslide location data and showed 83.47% prediction accuracy. That emphasized a strong relationship between the susceptibility map and the existing landslide location data. The results of this study can form a basis stable development and land use planning for the region.  相似文献   

Provenance of sediment in the Labrador Current: a record of hinterland glaciation over the past 125 ka          下载免费PDF全文

LONGJIANG MAO  DAVID J. W. PIPER  FRANCKY SAINT‐ANGE  JOHN T. ANDREWS  MARKUS KIENAST 《第四纪科学杂志》2014,29(7):650-660

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North‐eastern Laurentide,western Greenland and southern Innuitian ice stream dynamics during the last glacial cycle          下载免费PDF全文

QUENTIN SIMON  CLAUDE HILLAIRE‐MARCEL  GUILLAUME ST‐ONGE  JOHN T. ANDREWS 《第四纪科学杂志》2014,29(1):14-26

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Postglacial variability in near‐bottom current speed on the continental shelf off south‐west Spitsbergen          下载免费PDF全文

BEATA STERNAL  WITOLD SZCZUCISKI  MATTHIAS FORWICK  MAREK ZAJĄCZKOWSKI  STANISŁAW LORENC  JOANNA PRZYTARSKA 《第四纪科学杂志》2014,29(8):767-777

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渝东南下古生界页岩构造裂缝形成及分布控制因素          下载免费PDF全文

岳锋  程礼军  焦伟伟  王飞 《地质科学》2016,(4):1090-1100

天然裂缝对页岩气储集和渗流有重要影响,但目前对页岩构造裂缝研究不够深入。本文通过露头、岩心裂缝观察和分析,探讨了渝东南下古生界页岩构造裂缝类型、形成机理及分布控制因素。基于裂缝特征及力学成因,将剪切裂缝分为高角度剪切裂缝、倾斜滑脱裂缝和水平滑脱裂缝。倾斜滑脱裂缝是在上覆岩层重力和水平构造应力共同作用下沿应力集中的软弱面发生剪切滑动形成,水平滑脱裂缝是在构造挤压应力作用条件下主要沿页理面方向的剪切或层间滑动形成;页理发育程度及岩层曲率是控制水平滑脱裂缝形成的关键因素,岩石矿物组成、构造作用及岩层厚度是控制其它类型构造裂缝形成和分布的主要因素,页岩岩石力学层的划分需要根据裂缝特征、岩性变化特征、岩石力学参数及沉积界面等综合确定,岩层厚度与层间构造裂缝密度呈负相关关系。  相似文献   

四川盆地西南部第三纪盆地原型及其演化          下载免费PDF全文

黄涵宇  何登发 《地质科学》2016,(2):354-383

第三纪是四川盆地大范围陆相沉积历史的最后阶段, 同时又是四川盆地重要的构造定形期.探究该时期原型盆地沉积充填规律与构造演化特征, 是揭示四川盆地形成演化过程, 还原其古地理、古气候演变的关键.在综合利用古地磁、地震、野外露头等资料的基础之上, 从盆-山结合的角度出发, 以地质历史时间为主要线索, 对第三纪原型盆地分阶段、分区域地进行了动态化分析研究.重建了各沉积时期原型盆地构造-古地理格局, 分析了盆地沉积充填规律并复原了不同阶段沉积相带的空间展布特征.主要受周缘山系逆冲推覆作用产生的构造负载和盆地基底构造的影响, 第三纪时期四川盆地沉积范围局限于西南部、南部地区, 以河、湖沉积环境为主, 处于持续地挤压、充填过程而具有萎缩消亡的趋势.现今残余第三系地层由老到新, 主要由名山组、芦山组、大邑砾岩组等地层组成(先后经历了: 受造山带挤压推覆作用和温暖干旱气候等因素影响, 发育湖盆边缘冲积扇和沙漠沉积环境, 处于快速沉降阶段的名山组沉积时期; 以及构造活动相对稳定, 湖盆面积不断减小, 以沙泥质沉积互层为特征的芦山组沉积时期; 和沿山前带由南向北迁移, 以发育大型冲积扇为特征的大邑砾岩组沉积时期).纵观整个第三纪构造演化历史, 反映出四川盆地西南部地区在第三纪时期表现为典型的陆内坳陷沉积盆地性质.同期的大地构造活动和气候变化等因素对原型盆地的形成与演化起到了重要的控制作用, 同时也对该时期盆地古地理格局和沉积充填规律产生了重要影响.  相似文献   

下扬子南黄海沉积盆地构造地质特征   总被引：6，自引：0，他引：6  

庞玉茂  张训华  肖国林  温珍河  郭兴伟  侯方辉  朱晓青 《地质论评》2016,62(3):604-616

南黄海盆地作为下扬子块体之上的大型叠合盆地,海相构造层保存完整,陆相断拗构造层也较为发育,盆地地质结构复杂,构造变形强烈,利用最新的地质地球物理资料和解释成果,对低勘探程度的南黄海盆地进行了研究,认为盆地演化大致经历了克拉通被动陆缘初始发育阶段—南缘前陆北缘被动陆缘过渡阶段—南北对冲前陆定型阶段—滨太平洋弧后陆内调整四个阶段。南黄海盆地属于台地—断拗复合地质结构,中、新生代为具有盆内隆起带的断陷箕状结构,且中、新生代多期构造运动在盆地原型改造和后期沉积发育上起着至关重要的作用,尤其印支—燕山早期运动、燕山中期黄桥运动和喜马拉雅期盐城运动与盆地地层变形、沉积发育、断裂发育及构造样式等盆地要素演化密切相关,进而导致盆地垂向地质结构和构造变形的层次性极为显著,而中生代燕山期和新生代喜马拉雅期两期构造岩浆活动则与滨太平洋域的动力学背景相关。  相似文献   

上扬子会泽地区早三叠世飞仙关组砂岩物源特征:来自重矿物铬尖晶石和碎屑锆石的限定   总被引：1，自引：0，他引：1  

张英利  王宗起  王刚  李谦  林健飞 《地质论评》2016,62(1):54-72

上扬子会泽地区早三叠世飞仙关组主要为河流相的紫红色砂岩,物源主要来自于西部和西北部。碎屑重矿物组合表明物源主要来自于岩浆岩,且重矿物中发现大量碎屑铬尖晶石和锆石。本文运用电子探针微区成分分析和碎屑锆石U-Pb测年方法,对上扬子早三叠世飞仙关组砂岩中铬尖晶石和碎屑锆石进行分析。铬尖晶石电子探针化学成分分析显示,其具有高铬、低Fe~(3+)和高TiO_2含量的特征,源岩分析指示这些铬尖晶石来源于与洋岛/板内、岛弧以及大火成岩省相关的火成岩。同时,碎屑锆石LA-ICP-MS U-Pb年龄测定表明,飞仙关组的物源主要来自于248~272Ma和715~997Ma的岩浆岩。铬尖晶石和碎屑锆石综合分析表明,248~272Ma的物源岩石具有大火成岩省玄武岩特征,主要为峨眉山玄武岩及同期基性侵入岩;715~997M的物源为洋岛/板内玄武岩类,主要为研究区周缘与新元古代苏雄组及其同期的岩浆岩;铬尖晶石指示的岛弧性质物源则可能源自1000~1100Ma的岩浆岩。同时,碎屑锆石还指示古元古代和早寒武世发育岩浆作用,且存在古老的新太古代结晶基底。这些资料为上扬子地区构造演化提供了沉积学的证据。  相似文献